View source for Polychlorinated biphenyl

{{Short description|Highly carcinogenic chemical compounds}}
{{redirect|PCBs||PCB (disambiguation)}}
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| ImageFile = Polychlorinated biphenyl structure.svg
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| ImageCaption =Chemical structure of PCBs. The possible positions of [[chlorine]] atoms on the [[benzene ring]]s are denoted by numbers assigned to the [[carbon]] atoms.
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| Section1 = {{Chembox Identifiers
| CASNo = 1336-36-3
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| Section2 = {{Chembox Properties
| Formula = [[Carbon|C]]<sub>12</sub>[[Hydrogen|H]]<sub>10−''x''</sub>[[Chloride|Cl]]<sub>''x''</sub>
| MolarMass = Variable
| Appearance = Light yellow or colorless, thick, oily liquids<ref>{{Cite web | url = http://nj.gov/health/eoh/rtkweb/documents/fs/1554.pdf | title = Hazardous Substance Fact Sheet | publisher = New Jersey Department of Health}}</ref>
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| Section3 = {{Chembox Hazards
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[[File:CP-SLOPE-wb-gantry-power-supply-transformer-PCB-warning.jpg|thumb|upright|PCB warning label on a power transformer known to contain PCBs]]

'''Polychlorinated biphenyls''' ('''PCBs''') are [[organochlorine compound]]s with the formula [[Carbon|C]]<sub>12</sub>[[Hydrogen|H]]<sub>10−''x''</sub>[[Chloride|Cl]]<sub>''x''</sub>. They were once widely used in the manufacture of [[carbonless copy]] paper, as [[heat transfer fluid]]s, and as [[dielectric]] and [[coolant]] fluids for electrical equipment.<ref name=Ullmann>{{Ullmann|doi=10.1002/14356007.a06_233.pub2 |title=Chlorinated Hydrocarbons |year=2006 | vauthors = Rossberg M, Lendle W, Pfleiderer G, Tögel A, Dreher EL, Langer E, Rassaerts H, Kleinschmidt P, Strack H, Cook R, Beck U, Lipper KA, Torkelson TR, Löser E, Beutel KK, Mann T | display-authors = 3 |isbn=3527306730}}</ref> They are highly toxic and [[carcinogen]]ic chemical compounds, formerly used in industrial and consumer electronic products, whose production was banned  internationally by the [[Stockholm Convention on Persistent Organic Pollutants]] in 2001.

Because of their longevity, PCBs are still widely in use, even though their manufacture has declined drastically since the 1960s, when a multitude of problems were identified.<ref>{{cite book |veditors=Robertson LW, Hansen LG |title=PCBs: Recent advances in environmental toxicology and health effects |date=2004 |publisher=University Press of Kentucky |location=Lexington, KY |isbn=978-0-8131-2226-7 |page=11}}</ref> With the discovery of PCBs' environmental [[toxicity]], and classification as [[persistent organic pollutant]]s, their production was banned for most uses by United States federal law on January 1, 1978.

The International Agency for Research on Cancer (IARC) rendered PCBs as definite carcinogens in humans. According to the [[U.S. Environmental Protection Agency]] (EPA), PCBs cause cancer in animals and are probable human carcinogens.<ref name="EPA">{{cite web |url=https://19january2017snapshot.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs_.html#healtheffects |title=Health Effects of PCBs |publisher=U.S. Environmental Protection Agency (EPA) |location=Washington, D.C. |date=2016-09-15}}</ref> Moreover, because of their use as a coolant in electric transformers, PCBs still persist in built environments.<ref>{{Cite report |date=2020-09-29|title=Current intelligence bulletin 45 – polychlorinated biphenyls (PCB's): potential health hazards from electrical equipment fires or failures (with reference package).|url=https://www.cdc.gov/niosh/docs/86-111/default.html|language=en-us|doi=10.26616/NIOSHPUB86111|url-access=subscription}}</ref><ref>{{Cite web |title=Identification, Management, and Proper Disposal of PCB-Containing Electrical Equipment used in Mines|url=https://www.epa.gov/sites/default/files/documents/pcbidmgmt.pdf |archive-url=https://web.archive.org/web/20220110213317/https://www.epa.gov/sites/default/files/documents/pcbidmgmt.pdf |archive-date=2022-01-10 |url-status=live|website=Environmental Protection Agency}}</ref>

Some PCBs share [[dioxin-like compound|a structural similarity and toxic mode of action]] with [[Polychlorinated dibenzodioxins|dioxin]]s.<ref>{{cite web|title=Dioxins and PCBs |url=http://www.efsa.europa.eu/en/topics/topic/dioxins-and-pcbs|publisher=European Food Safety Authority|access-date=13 October 2015}}</ref> Other toxic effects such as [[endocrine disruption]] (notably blocking of thyroid system functioning) and [[neurotoxicity]] are known.<ref>{{cite journal |vauthors=Boas M, Feldt-Rasmussen U, Skakkebaek NE, Main KM |title=Environmental chemicals and thyroid function |journal=European Journal of Endocrinology |volume=154 |issue=5 |pages=599–611 |date=May 2006 |pmid=16645005 |doi=10.1530/eje.1.02128 |doi-access=free}}</ref> The [[bromine]] analogues of PCBs are [[polybrominated biphenyl]]s (PBBs), which have analogous applications and environmental concerns.

An estimated 1.2 million tons have been produced globally.<ref name=":2">{{Cite book|title=Reproductive and Developmental Toxicology|date=2011|publisher=Academic Press| vauthors = Gupta RC |isbn=978-0-12-382033-4|location=London|chapter=41 Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans|oclc=717387050}}</ref> Though the US EPA enforced the federal ban as of 1978, PCBs continued to create health problems in later years through their continued presence in soil and sediment, and from products which were made before 1979.<ref name=healthafter>{{cite news | vauthors = Chappell B |title=Bayer To Pay More Than $10 Billion To Resolve Cancer Lawsuits Over Weedkiller Roundup |url=https://www.npr.org/2020/06/24/882949098/bayer-to-pay-more-than-10-billion-to-resolve-roundup-cancer-lawsuits |access-date=26 June 2020 |publisher=NPR |date=24 June 2020}}</ref> In 1988, Japanese scientists Tanabe et al. estimated 370,000 tons were in the environment globally, and 780,000 tons were present in products, landfills, and dumps or kept in storage.<ref name=":2" />

==Physical and chemical properties==
===Physical properties===
The compounds are pale-yellow [[viscosity|viscous]] [[liquid]]s. They are hydrophobic, with low [[water (molecule)|water]] [[solubility|solubilities]]: 0.0027–0.42&nbsp;[[nanogram|ng]]/L for [[Monsanto#Polychlorinated_biphenyls_(PCBs)|Aroclors brand]],<ref name="unep"/> but they have high solubilities in most organic [[solvent]]s, oils, and [[fat]]s. They have low [[vapor pressure]]s at room temperature. They have [[dielectric constant]]s of 2.5–2.7,<ref>{{cite web|title=PCB Transformers and Capacitors from management to Reclassification to Disposal |url=http://www.chem.unep.ch/pops/pdf/PCBtranscap.pdf |archive-url=https://web.archive.org/web/20030621170714/http://www.chem.unep.ch/pops/pdf/PCBtranscap.pdf |archive-date=2003-06-21 |website=chem.unep.ch |publisher=United Nations Environmental Program |access-date=2014-12-30 |pages=55, 63}}</ref> very high [[thermal conductivity]],<ref name="unep" />{{page needed|date=October 2015}} and high [[flash point]]s (from 170 to 380&nbsp;°C).<ref name="unep" />{{page needed|date=October 2015}}

The density varies from 1.182 to 1.566&nbsp;g/cm<sup>3</sup>.<ref name="unep"/>{{page needed|date=October 2015}} Other physical and chemical properties vary widely across the class. As the degree of chlorination increases, melting point and [[lipophilicity]] increase, and vapour pressure and water solubility decrease.<ref name="unep"/>{{page needed|date=October 2015}}

PCBs do not easily break down or degrade, which made them attractive for industries. PCB mixtures are resistant to acids, bases, oxidation, hydrolysis, and temperature change.<ref>{{Cite book |url=https://books.google.com/books?id=mOvJCEEzlAgC |title=Halogenated Biphenyls, Terphenyls, Naphthalenes, Dibenzodioxins and Related Products | veditors = Kimbrough RD, Jensen AA |date=2012 |publisher=Elsevier |isbn=978-0-444-59892-9|page=24}}</ref> They can generate extremely toxic [[Polychlorinated dibenzodioxins|dibenzodioxins]] and [[dibenzofuran]]s through partial oxidation. Intentional degradation as a treatment of unwanted PCBs generally requires high heat or [[catalysis]] (see [[#Methods of destruction|Methods of destruction]] below).

PCBs readily penetrate [[absorption (skin)|skin]], [[Polyvinyl chloride|PVC]] (polyvinyl chloride), and [[latex]] (natural rubber).<ref name="anzecc">{{cite book |title=Identifying PCB-Containing Capacitors |publisher=Australian and New Zealand Environment and Conservation Council |pages=4–5 |year=1997 |isbn=978-0-642-54507-7 |url=http://www.environment.gov.au/settlements/publications/chemicals/scheduled-waste/pubs/pcbid.pdf |access-date=2007-07-07 |archive-url=https://web.archive.org/web/20121003010739/http://www.environment.gov.au/settlements/publications/chemicals/scheduled-waste/pubs/pcbid.pdf |archive-date=2012-10-03}}</ref> PCB-resistant materials include [[Viton]], [[polyethylene]], [[polyvinyl acetate]] (PVA), [[polytetrafluoroethylene]] (PTFE), [[butyl rubber]], [[nitrile rubber]], and [[Neoprene]].<ref name="anzecc"/>

===Structure and toxicity===
PCBs are derived from [[biphenyl]], which has the formula C<sub>12</sub>H<sub>10</sub>, sometimes written (C<sub>6</sub>H<sub>5</sub>)<sub>2</sub>. In PCBs, some of the hydrogen atoms in biphenyl are replaced by chlorine atoms. There are 209 different chemical compounds in which one to ten chlorine atoms can replace hydrogen atoms. PCBs are typically used as mixtures of compounds and are given the single identifying [[CAS registry number|CAS number]] {{CAS|1336-36-3}}. About 130 different individual PCBs are found in commercial PCB products.<ref name="unep">{{cite book | author=UNEP Chemicals | title=Guidelines for the Identification of PCBs and Materials Containing PCBs | issue=1 | publisher=United Nations Environment Programme | year=1999 | page=40 | url=http://www.chem.unep.ch/pops/pdf/PCBident/pcbid1.pdf | access-date=2007-11-07 | archive-url=https://web.archive.org/web/20080414094255/http://www.chem.unep.ch/pops/pdf/PCBident/pcbid1.pdf | archive-date=2008-04-14}}</ref>{{rp|2}}

Toxic effects vary depending on the specific PCB. In terms of their structure and toxicity, PCBs fall into two distinct categories, referred to as coplanar or non-''ortho''-substituted [[arene substitution patterns]] and noncoplanar or ''ortho''-substituted [[Congener (chemistry)|congener]]s.

[[File:dl-PCB beschriftet.svg|thumb|upright=2|Structures of the twelve dioxin-like PCBs]]
;Coplanar or non-''ortho''
:The coplanar group members have a fairly rigid structure, with their two phenyl rings in the same plane. It renders their structure similar to [[polychlorinated dibenzo-p-dioxins|polychlorinated dibenzo-''p''-dioxins]] (PCDDs) and [[polychlorinated dibenzofurans]], and allows them to act like PCDDs, as an agonist of the [[aryl hydrocarbon receptor]] (AhR) in organisms. They are considered as contributors to overall dioxin toxicity, and the term [[dioxins and dioxin-like compounds]] is often used interchangeably when the environmental and toxic impact of these compounds is considered.<ref>{{cite journal | vauthors = Safe S | title = Polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs): biochemistry, toxicology, and mechanism of action | journal = Critical Reviews in Toxicology | volume = 13 | issue = 4 | pages = 319–395 | year = 1984 | pmid = 6091997 | doi = 10.3109/10408448409023762 }}</ref><ref>{{cite journal | vauthors = Safe S, Bandiera S, Sawyer T, Robertson L, Safe L, Parkinson A, Thomas PE, Ryan DE, Reik LM, Levin W | display-authors = 3 | title = PCBs: structure-function relationships and mechanism of action | journal = Environmental Health Perspectives | volume = 60 | pages = 47–56 | date = May 1985 | pmid = 2992927 | pmc = 1568577 | doi = 10.1289/ehp.856047 | jstor = 3429944 | bibcode = 1985EnvHP..60...47S }}</ref>

;Noncoplanar
:Noncoplanar PCBs, with chlorine atoms at the ''ortho'' positions can cause neurotoxic and immunotoxic effects, but only at concentrations much higher than those normally associated with dioxins. However, as they are typically found at much higher levels in biological and environmental samples they also pose health concerns, particularly to developing animals (including humans). As they do not activate the AhR, they are not considered part of the dioxin group. Because of their lower overt toxicity, they have typically been of lesser concern to regulatory bodies.<ref>{{cite journal | vauthors = Winneke G, Bucholski A, Heinzow B, Krämer U, Schmidt E, Walkowiak J, Wiener JA, Steingrüber HJ | display-authors = 3 | title = Developmental neurotoxicity of polychlorinated biphenyls (PCBS): cognitive and psychomotor functions in 7-month old children | journal = Toxicology Letters | volume = 102–103 | pages = 423–428 | date = December 1998 | pmid = 10022290 | doi = 10.1016/S0378-4274(98)00334-8 }}</ref><ref>{{cite book |title=A Risk Management Strategy for PCB-Contaminated Sediments |url=https://www.nap.edu/catalog/10041/a-risk-management-strategy-for-pcb-contaminated-sediments |author=National Research Council (United States) |publisher = National Academies Press |location=Washington, D.C. |date=2001 |doi=10.17226/10041 |isbn=978-0-309-07321-9}}</ref>

Di-''ortho''-substituted, non-coplanar PCBs interfere with intracellular [[signal transduction]] dependent on [[Calcium in biology|calcium]] which may lead to [[neurotoxicity]].<ref>{{cite journal | vauthors = Simon T, Britt JK, James RC | title = Development of a neurotoxic equivalence scheme of relative potency for assessing the risk of PCB mixtures | journal = Regulatory Toxicology and Pharmacology | volume = 48 | issue = 2 | pages = 148–170 | date = July 2007 | pmid = 17475378 | doi = 10.1016/j.yrtph.2007.03.005 }}</ref> ''ortho''-PCBs can disrupt [[thyroid hormone]] transport by binding to [[transthyretin]].<ref>{{cite journal | vauthors = Chauhan KR, Kodavanti PR, McKinney JD | title = Assessing the role of ortho-substitution on polychlorinated biphenyl binding to transthyretin, a thyroxine transport protein | journal = Toxicology and Applied Pharmacology | volume = 162 | issue = 1 | pages = 10–21 | date = January 2000 | pmid = 10631123 | doi = 10.1006/taap.1999.8826 | bibcode = 2000ToxAP.162...10C | url = https://zenodo.org/record/1229980 }}</ref>
{{Clear}}

==Mixtures and trade names==
Commercial PCB mixtures were marketed under the following names:<ref>{{cite web|title=Proceedings of the Subregional Awareness Raising Workshop on Persistent Organic Pollutants (POPs), Bangkok, Thailand |publisher=[[United Nations Environment Programme]] |date=25 November 1997 |url=http://www.chem.unep.ch/pops/POPs_Inc/proceedings/bangkok/FIEDLER1.html |access-date=2007-12-11 |archive-url=https://web.archive.org/web/20070808144938/http://www.chem.unep.ch/pops/POPs_Inc/proceedings/bangkok/FIEDLER1.html |archive-date=8 August 2007}}</ref><ref>{{cite web |title=Brand names of PCBs — What are PCBs? |publisher=Japan Offspring Fund / Center for Marine Environmental Studies (CMES), Ehime University, Japan |year=2003 |url=http://tabemono.info/report/former/pcd/2/2_2/e_1.html |access-date=2008-02-11}}</ref>

{{div col|colwidth=22em}}
'''Brazil'''
* Ascarel

'''Czech Republic and Slovakia'''
*Delor

'''France'''
*Phenoclor
*Pyralène (both used by Prodolec)

'''Germany'''
*Clophen (used by [[Bayer]])

'''Italy'''
*Apirolio
*Fenclor

'''Japan'''
*Kanechlor (used by Kanegafuchi)
*Santotherm (used by [[Mitsubishi]])
*Pyroclor

'''Former USSR'''
*Sovol
*Sovtol

'''United Kingdom'''
*Aroclor xxxx (used by [[Monsanto Company]])
*Askarel

'''United States'''
*Aroclor xxxx (used by [[Monsanto Company]])
*Asbestol
*Askarel
*Bakola131
*Chlorextol – [[Allis-Chalmers]] trade name
*Dykanol (Cornell-Dubilier)
*Hydol
*Inerteen (used by [[Westinghouse Electric Corporation (1886)|Westinghouse]])
*Noflamol
*Pyranol/Pyrenol, Clorinol (used in [[General Electric]]'s oil-filled "clorinol"-branded metal can [[capacitor]]s. Utilized from the early 1960s to late 1970s in air conditioning units, Seeburg jukeboxes and Zenith televisions)
* Saf-T-Kuhl
*[[Therminol]] FR Series ([[Monsanto]] ceased production in 1971<ref>{{cite journal | vauthors = Erickson MD, Kaley RG | title = Applications of polychlorinated biphenyls | journal = Environmental Science and Pollution Research International | volume = 18 | issue = 2 | pages = 135–151 | date = February 2011 | pmid = 20848233 | doi = 10.1007/s11356-010-0392-1 | url = http://cdn.eastchem.com/therminol/Applications_of_PCBs_Erickson_Kaley_Aug2010_AuthorsProof_0.pdf | access-date = 2015-03-03 | publisher = Springer-Verlag | bibcode = 2011ESPR...18..135E | s2cid = 25260209 | archive-url = https://web.archive.org/web/20150402163101/http://cdn.eastchem.com/therminol/Applications_of_PCBs_Erickson_Kaley_Aug2010_AuthorsProof_0.pdf | archive-date = 2015-04-02 }}</ref>).
{{div col end}}

===Aroclor mixtures ===
The only North American producer, [[Monsanto Company]], marketed PCBs under the trade name '''Aroclor''' from 1930 to 1977. These were sold under trade names followed by a four-digit number. In general, the first two digits refer to the product series as designated by Monsanto (e.g., 1200 or 1100 series); the second two numbers indicate the percentage of chlorine by mass in the mixture. Thus, Aroclor 1260 is a 1200 series product and contains 60% chlorine by mass. It is a myth that the first two digits referred to the number of carbon atoms; the number of carbon atoms do not change in PCBs. The 1100 series was a crude PCB material which was distilled to create the 1200 series PCB product.<ref>{{cite journal | vauthors = Erickson MD, Kaley RG | title = Applications of polychlorinated biphenyls | journal = Environmental Science and Pollution Research International | volume = 18 | issue = 2 | pages = 135–151 | date = February 2011 | pmid = 20848233 | doi = 10.1007/s11356-010-0392-1 | bibcode = 2011ESPR...18..135E | s2cid = 25260209 }}</ref>

The exception to the naming system is Aroclor 1016 which was produced by distilling 1242 to remove the highly chlorinated congeners to make a more biodegradable product. "1016" was given to this product during Monsanto's research stage for tracking purposes but the name stuck after it was commercialized.

Different Aroclors were used at different times and for different applications. In electrical equipment manufacturing in the US, Aroclor 1260 and Aroclor 1254 were the main mixtures used before 1950; Aroclor 1242 was the main mixture used in the 1950s and 1960s until it was phased out in 1971 and replaced by Aroclor 1016.<ref name="unep"/>{{page needed|date=October 2015}}

==Production==
One estimate (2006) suggested that 1&nbsp;million tonnes of PCBs had been produced. 40% of this material was thought to remain in use.<ref name=Ullmann/> Another estimate put the total global production of PCBs on the order of 1.5&nbsp;million tonnes. The United States was the single largest producer with over 600,000 tonnes produced between 1930 and 1977. The European region follows with nearly 450,000 tonnes through 1984. It is unlikely that a full inventory of global PCB production will ever be accurately tallied, as there were factories in Poland, East Germany, and Austria that produced unknown amounts of PCBs. {{As of|2002}}, there were still 21,500 tons of PCBs stored in the easternmost regions of Slovakia.<ref>{{cite journal | vauthors = Breivik K, Sweetman A, Pacyna JM, Jones KC | title = Towards a global historical emission inventory for selected PCB congeners—a mass balance approach. 1. Global production and consumption | journal = The Science of the Total Environment | volume = 290 | issue = 1–3 | pages = 181–198 | date = May 2002 | pmid = 12083709 | doi = 10.1016/S0048-9697(01)01075-0 | bibcode = 2002ScTEn.290..181B }}</ref>

Although deliberate production of PCBs is banned by international treaty, significant amounts of PCBs are still being "inadvertently" produced. Research suggests that 45,000 tons of 'by-product' PCBs are legally produced per year in the US as part of certain chemical and product formulations.<ref>{{Cite news |last1=Salvidge |first1=Rachel |last2=Hosea |first2=Leana |date=2024-03-08 |title=Cancer-causing PCB chemicals still being produced despite 40-year-old ban |url=https://www.theguardian.com/environment/2024/mar/08/cancer-causing-pcb-chemicals-still-produced-despite-40-year-old-ban |access-date=2024-03-08 |work=The Guardian }}</ref><ref>{{cite journal |last1=Megson |first1=David |last2=Idowu |first2=Ifeoluwa Grace |last3=Sandau |first3=Courtney D. |title=Is current generation of polychlorinated biphenyls exceeding peak production of the 1970s? |journal=Science of the Total Environment |date=May 2024 |volume=924 |article-number=171436 |doi=10.1016/j.scitotenv.2024.171436 |pmid=38447728 |bibcode= 2024ScTEn.92471436M}}</ref>

Commercial production of PCBs was banned in the United States in 1979, with the passage of the [[Toxic Substances Control Act]] (TSCA).<ref name="epa">{{cite web|website=United States Environmental Protection Agency|title=Polychlorinated Biphenyls|date=April 12, 2023|url=https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls}}</ref>

==Applications==
The utility of PCBs is based largely on their chemical stability, including low [[fire|flammability]] and high dielectric constant. In an electric arc, PCBs generate incombustible gases.

Use of PCBs is commonly divided into closed and open applications.<ref name="Ullmann" /> Examples of closed applications include [[coolant]]s and insulating fluids ([[transformer oil]]) for [[transformer]]s and [[capacitor]]s, such as those used in old fluorescent light ballasts,<ref>{{cite book | vauthors = Godish T |year=2001 |title=Indoor environmental quality |url=https://archive.org/details/indoorenvironmen00godi_372 |url-access=limited |edition=1st |pages=[https://archive.org/details/indoorenvironmen00godi_372/page/n402 110]–30 |location=Boca Raton, FL |publisher=Lewis Publishers|isbn=978-1-56670-402-1 }}</ref> and [[hydraulic fluid]]s considered a semi-closed application. In contrast, the major open application of PCBs was in [[carbonless copy paper|carbonless copy ("NCR") paper]], which even presently results in paper contamination.<ref name=":0">{{cite journal | vauthors = Pivnenko K, Olsson ME, Götze R, Eriksson E, Astrup TF |display-authors=3| title = Quantification of chemical contaminants in the paper and board fractions of municipal solid waste | journal = Waste Management | volume = 51 | pages = 43–54 | date = May 2016 | pmid = 26969284 | doi = 10.1016/j.wasman.2016.03.008 | bibcode = 2016WaMan..51...43P | s2cid = 22484869 | url = https://backend.orbit.dtu.dk/ws/files/140534798/Author_s_version.pdf }}</ref>

Other open applications were lubricating and cutting oils, and as [[plasticizer]]s in paints and cements, stabilizing additives in flexible PVC coatings of electrical cables and electronic components, [[pesticide]] extenders, reactive [[flame retardant]]s and [[sealant]]s for [[caulk]]ing, [[adhesive]]s, wood floor finishes, such as ''Fabulon'' and other products of [[Halowax]] in the U.S.,<ref name="rudel2008">{{cite journal | vauthors = Rudel RA, Seryak LM, Brody JG | title = PCB-containing wood floor finish is a likely source of elevated PCBs in residents' blood, household air and dust: a case study of exposure | journal = Environmental Health | volume = 7 | page = 2 | date = January 2008 | issue = 1 | pmid = 18201376 | pmc = 2267460 | doi = 10.1186/1476-069X-7-2 | doi-access = free | bibcode = 2008EnvHe...7....2R }}</ref> de-dusting agents, waterproofing compounds, casting agents.<ref name="unep" /> It was also used as a plasticizer in paints and especially "coal tars" that were used widely to coat water tanks, bridges and other infrastructure pieces.

Modern sources include [[pigment]]s, which may be used in [[ink]]s for paper or plastic products.<ref>{{cite journal | vauthors = Grossman E | title = Nonlegacy PCBs: pigment manufacturing by-products get a second look | journal = Environmental Health Perspectives | volume = 121 | issue = 3 | pages = A86–A93 | date = March 2013 | pmid = 23454657 | pmc = 3621189 | doi = 10.1289/ehp.121-a86 }}</ref> PCBs are also still found in old equipment like capacitors, ballasts, X-ray machines, and other e-waste.<ref name="E-scrap News">{{Cite news|date=April 15, 2021|title=In Our Opinion: Safe e-recycling of polychlorinated biphenyls|work=E-scrap News|url=https://resource-recycling.com/e-scrap/2021/04/15/in-our-opinion-safe-e-recycling-of-polychlorinated-biphenyls/|access-date=November 25, 2025|last1=Ceballos|first1=Diana|last2=Alvarez|first2=Marty}}</ref><ref>{{cite web|url=https://www.epa.gov/sites/default/files/2020-07/documents/pcb-x-ray-factsheet-final-july-2020.pdf|title=PCBs in Dental Office X-ray Machines: PCB Information and Reference Fact Sheet|publisher=U.S. Environmental Protection Agency|date=July 2020|access-date=November 25, 2025|id=Publication No. 530-F-20-004}}</ref>

==Environmental transport and transformations==
PCBs have entered the environment through both use and disposal. The environmental fate of PCBs is complex and global in scale.<ref name="unep"/>

===Water===
Because of their low [[vapour pressure]], PCBs accumulate primarily in the [[hydrosphere]], despite their [[hydrophobicity]], in the organic fraction of [[soil]], and in [[organism]]s including the human body.<ref>{{cite journal | vauthors = Norström K, Czub G, McLachlan MS, Hu D, Thorne PS, Hornbuckle KC |display-authors=3| title = External exposure and bioaccumulation of PCBs in humans living in a contaminated urban environment | journal = Environment International | volume = 36 | issue = 8 | pages = 855–861 | date = November 2010 | pmid = 19394084 | pmc = 2891214 | doi = 10.1016/j.envint.2009.03.005 | bibcode = 2010EnInt..36..855N }}</ref> The hydrosphere is the main reservoir. The immense volume of water in the oceans is still capable of dissolving a significant quantity of PCBs.<ref>{{cite web |title=A Look at How Long-Banned PCBs Persist in the Ocean |url=https://eos.org/research-spotlights/a-look-at-how-long-banned-pcbs-persist-in-the-ocean |website=Eos|date=7 May 2019 }}</ref>

As the pressure of ocean water increases with depth, PCBs become heavier than water and sink to the deepest ocean trenches where they are concentrated.<ref>{{cite news|url=https://www.economist.com/science-and-technology/2017/02/18/nasty-chemicals-abound-in-what-was-thought-an-untouched-environment|title=Nasty chemicals abound in what was thought an untouched environment|newspaper=The Economist|access-date=10 April 2022|date=18 February 2017}}</ref>

===Air===
A small volume of PCBs has been detected throughout the Earth's atmosphere. The atmosphere serves as the primary route for global transport of PCBs, particularly for those congeners with one to four chlorine atoms.<ref>{{cite book |doi=10.1016/B0-12-369400-0/00785-7 |chapter=Polychlorinated Biphenyls (PCBS) |title=Encyclopedia of Toxicology |date=2005 |last1=Kulkarni |first1=Swarupa G. |last2=Mehendale |first2=Harihara M. |pages=509–511 |isbn=978-0-12-369400-3 }}</ref>

In the atmosphere, PCBs may be degraded by [[hydroxyl radical]]s, or directly by [[photolysis]] of carbon–chlorine bonds (even if this is a less important process).<ref>{{cite journal |vauthors=Xin ML, Yang JW, Li Y |title=The mechanism for enhanced oxidation degradation of dioxin-like PCBs (PCB-77) in the atmosphere by the solvation effect |journal=Chemistry Central Journal |volume=11 |issue=1 |page=61 |date=July 2017 |pmid=29086899 |pmc=5503851 |doi=10.1186/s13065-017-0291-3 |doi-access=free }}</ref>

Atmospheric concentrations of PCBs tend to be lowest in rural areas, where they are typically in the [[picogram]] per cubic meter range, higher in suburban and urban areas, and highest in city centres, where they can reach 1&nbsp;[[nanogram|ng]]/m<sup>3</sup> or more.<ref>{{cite journal |last1=Diamond |first1=Miriam L. |last2=Melymuk |first2=Lisa |last3=Csiszar |first3=Susan A. |last4=Robson |first4=Matthew |title=Estimation of PCB Stocks, Emissions, and Urban Fate: Will our Policies Reduce Concentrations and Exposure? |journal=Environmental Science & Technology |date=15 April 2010 |volume=44 |issue=8 |pages=2777–2783 |doi=10.1021/es9012036 |pmid=20170162 |doi-access=free }}</ref> In [[Milwaukee]], an atmospheric concentration of 1.9&nbsp;ng/m<sup>3</sup> has been measured, and this source alone was estimated to account for 120&nbsp;kg/year of PCBs entering [[Lake Michigan]].<ref>{{cite journal |vauthors=Wethington DM, Hornbuckle KC |title=Milwaukee, WI, as a source of atmospheric PCBs to Lake Michigan |journal=Environmental Science & Technology |volume=39 |issue=1 |pages=57–63 |date=January 2005 |pmid=15667075 |doi=10.1021/es048902d |bibcode=2005EnST...39...57W}}</ref> In 2008, concentrations as high as 35&nbsp;[[nanogram|ng]]/m<sup>3</sup>, 10&nbsp;times higher than the EPA guideline limit of 3.4&nbsp;ng/m<sup>3</sup>, have been documented inside some houses in the U.S.<ref name="rudel2008"/>

Volatilization of PCBs in soil was thought to be the primary source of PCBs in the atmosphere, but research suggests ventilation of PCB-contaminated indoor air from buildings is the primary source of PCB contamination in the atmosphere.<ref>{{cite journal |vauthors=Jamshidi A, Hunter S, Hazrati S, Harrad S |title=Concentrations and chiral signatures of polychlorinated biphenyls in outdoor and indoor air and soil in a major U.K. conurbation |journal=Environmental Science & Technology |volume=41 |issue=7 |pages=2153–2158 |date=April 2007 |pmid=17438756 |doi=10.1021/es062218c |bibcode=2007EnST...41.2153J}}</ref>

===Biosphere===
In the [[biosphere]], PCBs can be degraded by the [[sun]], [[bacteria]] or [[eukaryote]]s, but the speed of the reaction depends on both the number and the disposition of chlorine atoms in the molecule: less substituted, ''meta''- or ''para''-substituted PCBs undergo biodegradation faster than more substituted congeners.{{Citation needed|date=May 2013}}

In bacteria, PCBs may be dechlorinated through [[reductive dechlorination]], or oxidized by [[dioxygenase]] enzyme.{{Citation needed|date=May 2013}} In eukaryotes, PCBs may be oxidized by the [[cytochrome P450]] enzyme.<ref>{{cite journal | vauthors = Tiedje JM, Quensen JF, Chee-Sanford J, Schimel JP, Boyd SA |display-authors=3| title = Microbial reductive dechlorination of PCBs | journal = Biodegradation | volume = 4 | issue = 4 | pages = 231–240 | date = 1993–1994 | pmid = 7764920 | doi = 10.1007/BF00695971 | s2cid = 2596703 }}</ref>
[[File:Biomagnification.svg|thumb|[[Biomagnification]] is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain.]]
Like many lipophilic toxins, PCBs undergo [[biomagnification]] and [[bioaccumulation]] primarily due to the fact that they are easily retained within organisms.<ref name=Schmidt>{{cite journal | vauthors = Schmidt C, Krauth T, Wagner S | title = Export of Plastic Debris by Rivers into the Sea | journal = Environmental Science & Technology | volume = 51 | issue = 21 | pages = 12246–12253 | date = November 2017 | pmid = 29019247 | doi = 10.1021/acs.est.7b02368 | bibcode = 2017EnST...5112246S | url = http://oceanrep.geomar.de/43169/4/es7b02368_si_001.pdf }}</ref><ref>{{cite journal | vauthors = Ferreira I, Venâncio C, Lopes I, Oliveira M | title = Nanoplastics and marine organisms: What has been studied? | journal = Environmental Toxicology and Pharmacology | volume = 67 | pages = 1–7 | date = April 2019 | pmid = 30685594 | doi = 10.1016/j.etap.2019.01.006 | bibcode = 2019EnvTP..67....1F | hdl = 10773/37415 | s2cid = 59306677 | hdl-access = free }}</ref>

Plastic pollution, specifically [[microplastics]], are a major contributor of PCBs into the biosphere and especially into marine environments. PCBs concentrate in marine environments because freshwater systems, like rivers, act as a bridge for plastic pollution to be transported from terrestrial environments into marine environments.<ref>{{Cite journal| vauthors = Ma P, Wei Wang M, Liu H, Feng Chen Y, Xia J |display-authors=3|date=2019-01-01|title=Research on ecotoxicology of microplastics on freshwater aquatic organisms|journal=Environmental Pollutants and Bioavailability|volume=31|issue=1|pages=131–137|doi=10.1080/26395940.2019.1580151 |doi-access=free|bibcode=2019EnvPB..31..131M }}</ref> It has been estimated that 88–95% of marine plastic is exported into the ocean by just 10 major rivers.<ref name=Schmidt/>

An organism can accumulate PCBs by consuming other organisms that have previously ingested PCBs from terrestrial, freshwater, or marine environments. The concentration of PCBs within an organism will increase over their lifetime; this process is called bioaccumulation. PCB concentrations within an organism also change depending upon which [[trophic level]] they occupy. When an organism occupies a high trophic level, like [[orcas]] or [[human]]s, they will accumulate more PCBs than an organism that occupies a low trophic level, like [[phytoplankton]]. If enough organisms with a trophic level are killed due to the accumulation of toxins, like PCB, a [[trophic cascade]] can occur.

PCBs can cause harm to human health or even death when eaten.<ref>{{cite news | vauthors = Faber H |title=Hunters who eat ducks warned on PCB hazard |url=https://www.nytimes.com/1981/10/08/nyregion/hunters-who-eat-ducks-warned-on-pcb-hazard.html |newspaper=New York Times |date=October 8, 1981}}</ref> PCBs can be transported by birds from aquatic sources onto land via feces and carcasses.<ref>{{cite journal | vauthors = Rapp Learn J |title=Seabirds Are Dumping Pollution-Laden Poop Back on Land |website=Smithsonian.com |date=November 30, 2015 |url=http://www.smithsonianmag.com/science-nature/seabirds-are-dumping-pollution-laden-poop-back-land-180957288/?no-ist|access-date=30 November 2015}}</ref>

==Biochemical metabolism==
===Overview===
PCBs undergo xenobiotic biotransformation, a mechanism used to make [[lipophilic]] toxins more polar and more easily excreted from the body.<ref name="pubs.acs.org">{{cite journal | vauthors = Richardson KL, Schlenk D | title = Biotransformation of 2,2',5,5'-tetrachlorobiphenyl (PCB 52) and 3,3',4,4'-tetrachlorobiphenyl (PCB 77) by liver microsomes from four species of sea turtles | journal = Chemical Research in Toxicology | volume = 24 | issue = 5 | pages = 718–725 | date = May 2011 | pmid = 21480586 | doi = 10.1021/tx1004562 }}</ref> The biotransformation is dependent on the number of chlorine atoms present, along with their position on the rings. Phase I reactions occur by adding an oxygen to either of the benzene rings by [[Cytochrome P450]].<ref>{{cite journal | vauthors = Forgue ST, Preston BD, Hargraves WA, Reich IL, Allen JR | title = Direct evidence that an arene oxide is a metabolic intermediate of 2,2',5,5'-tetrachlorobiphenyl | journal = Biochemical and Biophysical Research Communications | volume = 91 | issue = 2 | pages = 475–483 | date = November 1979 | pmid = 42397 | doi = 10.1016/0006-291x(79)91546-8 }}</ref> The type of P450 present also determines where the oxygen will be added; phenobarbital (PB)-induced P450s catalyze oxygenation to the meta-para positions of PCBs while 3-methylcholanthrene (3MC)-induced P450s add oxygens to the ''ortho''–''meta'' positions.<ref>{{cite journal | vauthors = Parke DV | year = 1985 | title = The role of cytochrome P-450 in the metabolism of pollutants | journal = Environmental Research | volume = 17 | issue = 2–4| pages = 97–100 | doi=10.1016/0141-1136(85)90049-2| bibcode = 1985MarER..17...97P }}</ref> PCBs containing ''ortho''–''meta'' and ''meta''–''para'' protons can be metabolized by either enzyme, making them the most likely to leave the organism. However, some metabolites of PCBs containing ''ortho''–''meta'' protons have increased [[steric hindrance]] from the oxygen, causing increased stability and an increased chance of accumulation.<ref>{{cite journal | vauthors = McFarland VA, Clarke JU | title = Environmental occurrence, abundance, and potential toxicity of polychlorinated biphenyl congeners: considerations for a congener-specific analysis | journal = Environmental Health Perspectives | volume = 81 | pages = 225–239 | date = May 1989 | pmid = 2503374 | pmc = 1567542 | doi = 10.1289/ehp.8981225 | bibcode = 1989EnvHP..81..225M }}</ref>

===Species dependent===
Metabolism is also dependent on the species of organism; different organisms have slightly different P450 enzymes that metabolize certain PCBs better than others. Looking at the PCB metabolism in the liver of four sea turtle species (green, [[olive ridley]], loggerhead and hawksbill), green and hawksbill sea turtles have noticeably higher [[hydroxylation]] rates of PCB 52 than olive ridley or loggerhead sea turtles. This is because the green and hawksbill sea turtles have higher P450 2-like protein expression. This protein adds three hydroxyl groups to PCB 52, making it more polar and water-soluble. P450 3-like protein expression that is thought to be linked to PCB 77 metabolism, something that was not measured in this study.<ref name="pubs.acs.org"/>

===Temperature dependent===
Temperature plays a key role in the ecology, physiology and metabolism of aquatic species. The rate of PCB metabolism was temperature dependent in [[yellow perch]] (''Perca flavescens''). In fall and winter, only 11 out of 72 introduced PCB congeners were excreted and had [[halflife|halflives]] of more than 1,000 days. During spring and summer when the average daily water temperature was above 20&nbsp;°C, persistent PCBs had halflives of 67 days. The main excretion processes were fecal egestion, growth dilution and loss across respiratory surfaces. The excretion rate of PCBs matched with the perch's natural [[bioenergetics]], where most of their consumption, respiration and growth rates occur during the late spring and summer. Since the perch is performing more functions in the warmer months, it naturally has a faster metabolism and has less PCB accumulation. However, multiple cold-water periods mixed with toxic PCBs with coplanar chlorine molecules can be detrimental to perch health.<ref>{{cite journal | vauthors = Paterson G, Drouillard KG, Haffner GD | title = PCB elimination by yellow perch (Perca flavescens) during an annual temperature cycle | journal = Environmental Science & Technology | volume = 41 | issue = 3 | pages = 824–829 | date = February 2007 | pmid = 17328189 | doi = 10.1021/es060266r | bibcode = 2007EnST...41..824P }}</ref>

===Sex dependent===
[[Enantiomer]]s of chiral compounds have similar chemical and physical properties, but can be metabolized by the body differently. This was looked at in [[bowhead whale]]s (''Balaena mysticetus'') for two main reasons: they are large animals with slow metabolisms (meaning PCBs will accumulate in fatty tissue) and few studies have measured chiral PCBs in cetaceans. They found that the average PCB concentrations in the blubber were approximately four times higher than the liver; however, this result is most likely age- and sex-dependent. As reproductively active females transferred PCBs and other poisonous substances to the fetus, the PCB concentrations in the blubber were significantly lower than males of the same body length (less than 13 meters).<ref>{{cite journal | vauthors = Hoekstra PF, Wong CS, O'Hara TM, Solomon KR, Mabury SA, Muir DC |display-authors=3| title = Enantiomer-specific accumulation of PCB atropisomers in the bowhead whale (Balaena mysticetus) | journal = Environmental Science & Technology | volume = 36 | issue = 7 | pages = 1419–1425 | date = April 2002 | pmid = 11999046 | doi = 10.1021/es015763g | bibcode = 2002EnST...36.1419H }}</ref>

==Health effects==
[[File:PCB-labelling.jpg|thumb|Labelling transformers containing PCBs]]

The toxicity of PCBs varies considerably among [[Congener (chemistry)|congeners]]. The [[coplanar]] PCBs, known as nonortho PCBs because they are not substituted at the ring positions ''[[Arene substitution patterns|ortho]]'' to (next to) the other ring, (such as PCBs 77, 126 and 169), tend to have [[Polychlorinated dibenzodioxins|dioxin]]-like properties, and generally are among the most toxic congeners. Because PCBs are almost invariably found in complex mixtures, the concept of toxic equivalency factors ([[Toxic equivalent factor|TEFs]]) has been developed to facilitate risk assessment and regulation, where more toxic PCB congeners are assigned higher TEF values on a scale from 0 to 1. One of the most toxic compounds known, [[2,3,7,8-tetrachlorodibenzodioxin|2,3,7,8-tetrachlorodibenzo[p]dioxin]], a [[polychlorinated dibenzodioxins|PCDD]], is assigned a TEF of 1.<ref>{{cite journal | vauthors = Van den Berg M, Birnbaum L, Bosveld AT, Brunström B, Cook P, Feeley M, Giesy JP, Hanberg A, Hasegawa R, Kennedy SW, Kubiak T, Larsen JC, van Leeuwen FX, Liem AK, Nolt C, Peterson RE, Poellinger L, Safe S, Schrenk D, Tillitt D, Tysklind M, Younes M, Waern F, Zacharewski T | display-authors = 3 | title = Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife | journal = Environmental Health Perspectives | volume = 106 | issue = 12 | pages = 775–792 | date = December 1998 | pmid = 9831538 | pmc = 1533232 | doi = 10.1289/ehp.98106775 | jstor = 3434121 | bibcode = 1998EnvHP.106..775V }}</ref> In June 2020, State Impact of Pennsylvania stated that "In 1979, the EPA banned the use of PCBs, but they still exist in some products produced before 1979. They persist in the environment because they bind to sediments and soils. High exposure to PCBs can cause birth defects, developmental delays, and liver changes."<ref name=healthafter />

===Exposure and excretion===
In general, people are exposed to PCBs overwhelmingly through food, much less so by breathing contaminated air, and least by skin contact. Once exposed, some PCBs may change to other chemicals inside the body. These chemicals or unchanged PCBs can be excreted in feces or may remain in a person's body for years, with half lives estimated at 10–15 years.<ref name=Crinnion/> PCBs collect in [[body fat]] and milk fat.<ref name=ATSDR>{{cite web |title=Public Health Statement for Polychlorinated Biphenyls (PCBs) |website=Toxic Substances Portal |publisher=U.S. Agency for Toxic Substances and Disease Registry |location=Atlanta, GA |url=https://www.atsdr.cdc.gov/PHS/PHS.asp?id=139&tid=26 |date=2015-01-21 |access-date=2020-05-24 |archive-date=2020-06-21 |archive-url=https://web.archive.org/web/20200621121007/https://www.atsdr.cdc.gov/phs/phs.asp?id=139&tid=26 }}</ref> PCBs [[biomagnification|biomagnify]] up the [[food web]] and are present in fish and overflow of contaminated aquifers.<ref>{{cite web |author1=Purdue University |author2=EPA |title=Exploring the Great Lakes. Bioaccumulation/Biomagnification Effects |url=https://www.epa.gov/sites/default/files/documents/bioaccumulationbiomagnificationeffects.pdf |publisher=EPA |location=Chicago, IL |access-date=3 October 2015 |page=2 |date=n.d. |archive-date=17 October 2015 |archive-url=https://web.archive.org/web/20151017184752/https://www2.epa.gov/sites/production/files/documents/bioaccumulationbiomagnificationeffects.pdf |url-status=live }}</ref> Human infants are exposed to PCBs through [[breast milk]] or by [[Environmental toxins in pregnancy|intrauterine exposure]] through transplacental transfer of PCBs<ref name=ATSDR/> and are at the top of the food chain.<ref>{{cite book | vauthors = Steingraber S |title=Having Faith: an ecologist's journey to motherhood |date=2001 |publisher=Berkley |location=New York |isbn=978-0-425-18999-3 |edition=Berkley trade pbk. |chapter=12 |chapter-url-access=registration |chapter-url=https://archive.org/details/havingfaithecolo00stei}}</ref>{{rp|249ff}}

Workers recycling old equipment in the electronics recycling industry can also be exposed to PCBs.<ref name="E-scrap News"/>

===Signs and symptoms===
====Humans====
The most commonly observed [[health effect]]s in people exposed to extremely high levels of PCBs are skin conditions, such as [[chloracne]] and [[rash]]es, but these were known to be symptoms of acute systemic poisoning dating back to 1922. Studies in workers exposed to PCBs have shown changes in [[blood]] and [[urine]] that may indicate [[liver]] damage. In Japan in 1968, 280&nbsp;kg of PCB-contaminated [[rice bran oil]] was used as chicken feed, resulting in a mass poisoning, known as [[Yushō disease]], in over 1800 people.<ref name="Aoki"/> Common symptoms included dermal and ocular [[lesion]]s, irregular [[menstrual cycle]]s and lowered [[immune response]]s.<ref name="Aoki"/><ref>"Yusho Disease."{{RareDiseases|8326}} U.S. Genetic and Rare Diseases Information Center, National Institutes of Health. Gaithersburg, MD.</ref><ref>{{cite web|title=PCB Baby Studies Part 2|url=http://www.foxriverwatch.com/baby_studies_pcbs_2.html|website=www.foxriverwatch.com|access-date=9 June 2016|archive-url=https://web.archive.org/web/20070609212253/http://www.foxriverwatch.com/baby_studies_pcbs_2.html|archive-date=9 June 2007}}</ref> Other symptoms included fatigue, headaches, coughs, and unusual skin sores.<ref name=HEALTH>{{cite web|url=http://www.healthgoods.com/Education/Health_Information/General_Health/environmental_diseases.htm |archive-url=https://web.archive.org/web/20060315152719/http://www.healthgoods.com/Education/Health_Information/General_Health/environmental_diseases.htm |archive-date=15 March 2006 |title= Environmental Diseases from A to Z}}</ref> Additionally, in children, there were reports of poor cognitive development.<ref name="Aoki"/> Women exposed to PCBs before or during pregnancy can give birth to children with lowered cognitive ability, compromised immune systems, and motor control problems.<ref>{{cite journal | vauthors = Jacobson JL, Jacobson SW | title = Intellectual impairment in children exposed to polychlorinated biphenyls in utero | journal = The New England Journal of Medicine | volume = 335 | issue = 11 | pages = 783–789 | date = September 1996 | pmid = 8703183 | doi = 10.1056/NEJM199609123351104 | doi-access = free }}{{Open access}}</ref><ref name=ATSDR/><ref>{{cite journal | vauthors = Stewart P, Reihman J, Lonky E, Darvill T, Pagano J |display-authors=3| title = Prenatal PCB exposure and neonatal behavioral assessment scale (NBAS) performance | journal = Neurotoxicology and Teratology | volume = 22 | issue = 1 | pages = 21–29 | date = January 2000 | pmid = 10642111 | doi = 10.1016/S0892-0362(99)00056-2 |bibcode=2000NTxT...22...21S}}</ref>

There is evidence that crash dieters that have been exposed to PCBs have an elevated risk of health complications. Stored PCBs in the [[adipose tissue]] become mobilized into the blood when individuals begin to crash diet.<ref>{{cite web |publisher=Agency for Toxic Substances and Disease Registry, CDC |date=1 September 2000 |title=PCBs: toxicity treatment and management |url=https://www.atsdr.cdc.gov/csem/csem.html |access-date=29 December 2023 |archive-date=4 February 2016 |archive-url=https://web.archive.org/web/20160204174821/http://www.atsdr.cdc.gov/csem/csem.asp?csem=7&po=7 }}</ref>

PCBs have shown toxic and [[mutagen]]ic effects by interfering with [[hormone]]s in the body. PCBs, depending on the specific congener, have been shown to both inhibit and imitate [[estradiol]], the main sex hormone in females. Imitation of the estrogen compound can feed estrogen-dependent [[breast cancer]] cells, and possibly cause other cancers, such as [[uterine cancer|uterine]] or [[cervical cancer|cervical]]. Inhibition of estradiol can lead to serious developmental problems for both males and females, including sexual, skeletal, and mental development issues.{{Citation needed|date=September 2016}}<ref>{{cite journal | vauthors = Winneke G | title = Developmental aspects of environmental neurotoxicology: lessons from lead and polychlorinated biphenyls | journal = Journal of the Neurological Sciences | volume = 308 | issue = 1–2 | pages = 9–15 | date = September 2011 | pmid = 21679971 | doi = 10.1016/j.jns.2011.05.020 | s2cid = 27726260 }}</ref> In a cross-sectional study, PCBs were found to be negatively associated with testosterone levels in adolescent boys.<ref>{{cite journal | vauthors = Schell LM, Gallo MV, Deane GD, Nelder KR, DeCaprio AP, Jacobs A |display-authors=3| title = Relationships of polychlorinated biphenyls and dichlorodiphenyldichloroethylene (p,p'-DDE) with testosterone levels in adolescent males | journal = Environmental Health Perspectives | volume = 122 | issue = 3 | pages = 304–309 | date = March 2014 | pmid = 24398050 | pmc = 3948020 | doi = 10.1289/ehp.1205984 |bibcode=2014EnvHP.122..304S}}</ref>

High PCB levels in adults have been shown to result in reduced levels of the thyroid hormone [[triiodothyronine]], which affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. It also resulted in reduced immunity and increased thyroid disorders.<ref name=Crinnion>{{cite journal | vauthors = Crinnion WJ | title = Polychlorinated biphenyls: persistent pollutants with immunological, neurological, and endocrinological consequences | journal = Alternative Medicine Review | volume = 16 | issue = 1 | pages = 5–13 | date = March 2011 | pmid = 21438643 | url = http://www.altmedrev.com/publications/16/1/5.pdf | access-date = 1 October 2015 | archive-date = 15 November 2015 | archive-url = https://web.archive.org/web/20151115083314/http://www.altmedrev.com/publications/16/1/5.pdf }}</ref><ref>{{cite journal | vauthors = Hagmar L, Rylander L, Dyremark E, Klasson-Wehler E, Erfurth EM |display-authors=3| title = Plasma concentrations of persistent organochlorines in relation to thyrotropin and thyroid hormone levels in women | journal = International Archives of Occupational and Environmental Health | volume = 74 | issue = 3 | pages = 184–188 | date = April 2001 | pmid = 11355292 | doi = 10.1007/s004200000213 | bibcode = 2001IAOEH..74..184H | s2cid = 5552427 }}</ref>{{ums|date=January 2018}}

====Animals====
Animals that eat PCB-contaminated food, even for short periods of time, suffer liver damage and may die. In 1968 in Japan, 400,000 birds died after eating poultry feed that was contaminated with PCBs.<ref>{{cite web |title=Contamination of rice bran oil with PCB used as the heating medium by leakage through penetration holes at the heating coil tube in deodorization chamber |publisher=Hatamura Institute for the Advancement of Technology |url=http://www.sozogaku.com/fkd/en/cfen/CB1056031.html |access-date=2007-12-11}}</ref> Animals that ingest smaller amounts of PCBs in food over several weeks or months develop various health effects, including [[anemia]]; acne-like skin conditions ([[chloracne]]); liver, [[stomach]], and [[thyroid]] gland injuries (including hepatocarcinoma),{{citation needed|date=May 2015}} and [[thymocyte]] [[apoptosis]].<ref name=Crinnion /> Other effects of PCBs in animals include changes in the [[immune system]], behavioral alterations, and impaired reproduction.<ref name=Crinnion/> PCBs that have [[Polychlorinated dibenzodioxins|dioxin]]-like activity are known to cause a variety of [[teratogenic]] effects in animals. Exposure to PCBs causes hearing loss and symptoms similar to hypothyroidism in rats.<ref>{{cite journal | vauthors = Goldey ES, Kehn LS, Lau C, Rehnberg GL, Crofton KM |display-authors=3| title = Developmental exposure to polychlorinated biphenyls (Aroclor 1254) reduces circulating thyroid hormone concentrations and causes hearing deficits in rats | journal = Toxicology and Applied Pharmacology | volume = 135 | issue = 1 | pages = 77–88 | date = November 1995 | pmid = 7482542 | doi = 10.1006/taap.1995.1210 |bibcode=1995ToxAP.135...77G| url = https://zenodo.org/record/1229966 }}</ref>

===Cancer===
In 2013, the [[International Agency for Research on Cancer]] (IARC) classified dioxin-like PCBs as human [[carcinogen]]s.<!--"On the basis of sufficient evidence of carcinogenicity in humans and experimental animals, the Working Group classified PCBs as carcinogenic to humans (Group 1)"--><ref name="Lauby-Secretan">{{cite journal | vauthors = Lauby-Secretan B, Loomis D, Grosse Y, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, Guha N, Baan R, Mattock H, Straif K | display-authors = 3 | title = Carcinogenicity of polychlorinated biphenyls and polybrominated biphenyls | journal = The Lancet. Oncology | volume = 14 | issue = 4 | pages = 287–288 | date = April 2013 | pmid = 23499544 | doi = 10.1016/s1470-2045(13)70104-9 | url = https://hal.archives-ouvertes.fr/hal-01607039/file/lauby-secretan_lancet_2013_1.pdf }}</ref>
According to the U.S. EPA, PCBs have been shown to cause cancer in animals and evidence supports a cancer-causing effect in humans.<ref name="EPA" /> Per the EPA, studies have found increases in malignant melanoma and rare liver cancers in PCB workers.<!--"Studies of PCB workers found increases in rare liver cancers and malignant melanoma. The presence of cancer in the same target organ (liver) following exposures to PCBs both in animals and in humans and the finding of liver cancers and malignant melanomas across multiple human studies adds weight to the conclusion that PCBs are probable human carcinogens. --><ref name = "EPA"/>

In 2013, the IARC determined that the evidence for PCBs causing [[non-Hodgkin lymphoma]] is "limited" and "not consistent".<ref name="Lauby-Secretan"/> In contrast an association between elevated blood levels of PCBs and non-Hodgkin lymphoma had been previously accepted.<ref>{{cite journal | vauthors = Kramer S, Hikel SM, Adams K, Hinds D, Moon K |display-authors=3| title = Current status of the epidemiologic evidence linking polychlorinated biphenyls and non-hodgkin lymphoma, and the role of immune dysregulation | journal = Environmental Health Perspectives | volume = 120 | issue = 8 | pages = 1067–1075 | date = August 2012 | pmid = 22552995 | pmc = 3440083 | doi = 10.1289/ehp.1104652 |bibcode=2012EnvHP.120.1067K}}</ref> PCBs may play a role in the development of cancers of the immune system because some tests of laboratory animals subjected to very high doses of PCBs have shown effects on the animals' immune system, and some studies of human populations have reported an association between environmental levels of PCBs and immune response.<ref name="EPA" />

===Lawsuits related to health effects===
{{POV section|date=July 2023}}
In the early 1990s, Monsanto faced several lawsuits over harm caused by PCBs from workers at companies such as Westinghouse that bought PCBs from Monsanto and used them to build electrical equipment.<ref>Robert Steyer. ''St. Louis Post-Dispatch''. November 25, 1991. "Settlement Doesn't End Monsanto's Woes". Accessed via Factiva July 12, 2020.</ref> Monsanto and its customers, such as Westinghouse and GE, also faced litigation from third parties, such as workers at scrap yards that bought used electrical equipment and broke them down to reclaim valuable metals.<ref>{{cite court |litigants= Monsanto Company, Appellant, v. William Reed, et al., Appellees. Westinghouse Electric Corporation, Appellant, v. Monsanto Company, et al., Appellees |vol= 95-SC-549-DG, 95-SC-561-DG |court= Supreme Court of Kentucky |date= April 24, 1997 |url= https://caselaw.findlaw.com/ky-supreme-court/1243307.html |access-date= }}</ref><ref>{{cite court |litigants= High v. Westinghouse Elec. Corp |vol= 610 So.2d 1259 |court= Supreme Court of Florida |date= June 11, 1992 |url= http://www.leagle.com/xmlResult.aspx?xmldoc=19921869610So2d1259_11621.xml&docbase=CSLWAR2-1986-2006|access-date= }}</ref> Monsanto settled some of these cases and won the others, on the grounds that it had clearly told its customers that PCBs were dangerous chemicals and that protective procedures needed to be implemented.<ref>{{Cite web |title=Lawsuit: Monsanto PCBs Continue To Drain Into Los Angeles Harbors, Lakes Decades After Being Banned By EPA |url=https://www.cbsnews.com/losangeles/news/lawsuit-monsanto-pcbs-drain-los-angeles-harbors-lakes-decades-after-epa-ban/ |access-date=2022-06-17 |website=www.cbsnews.com |date=8 March 2022 |language=en-US}}</ref>

In 2003, Monsanto and [[Solutia Inc.]], a Monsanto corporate spin-off, reached a $700 million settlement with the residents of [[Anniston, Alabama|West Anniston, Alabama]], who had been affected by the manufacturing and dumping of PCBs.<ref name="The New York Times">{{cite news | url=https://www.nytimes.com/2003/08/21/business/700-million-settlement-in-alabama-pcb-lawsuit.html | title=$700 Million Settlement in Alabama PCB Lawsuit | newspaper=The New York Times | date=21 August 2003 | access-date=12 July 2020}}</ref><ref name="Alabama"/> In a trial lasting six weeks, the jury found that "Monsanto had engaged in outrageous behavior, and held the corporations and its corporate successors liable on all six counts it considered&nbsp;– including negligence, nuisance, wantonness and suppression of the truth."<ref name="60 Minutes CBS News">{{cite web | url=http://www.cbsnews.com/news/toxic-secret-07-11-2002/ | title=Toxic Secret Alabama Town Was Never Warned Of Contamination | publisher=CBS News | date=November 2007 | access-date=12 July 2020 | vauthors = Crean E }}</ref>{{unreliable source?|reason=I don't think that's a real charge|date=July 2023}}

In 2014, the Los Angeles Superior Court found that Monsanto was not liable for cancers claimed to be from PCBs permeating the food supply of three plaintiffs who had developed non-Hodgkin's lymphoma. After a four-week trial, the jury found that Monsanto's production and sale of PCBs between 1935 and 1977 were not substantial causes of the cancer.<ref>{{cite web |url=http://www.law360.com/articles/540961/jury-finds-monsanto-pcbs-not-to-blame-for-cancer-cases|title=Jury Finds Monsanto PCBs Not To Blame For Cancer Cases| vauthors = Scurria A |publisher=Law360|date=22 May 2014|access-date=12 June 2020}}</ref>

In 2015, the cities of Spokane, San Diego, and San Jose initiated lawsuits against Monsanto to recover cleanup costs for PCB contaminated sites, alleging that Monsanto continued to sell PCBs without adequate warnings after they knew of their toxicity. Monsanto issued a media statement concerning the San Diego case, claiming that improper use or disposal by third-parties, of a lawfully sold product, was not the company's responsibility.<ref>{{cite news|title=Spokane sues Monsanto over Spokane River contamination|url=http://www.seattletimes.com/seattle-news/spokane-sues-monsanto-over-spokane-river-contamination/|agency=Associated Press|newspaper=The Seattle Times|date=3 August 2015}}</ref><ref>{{cite news| vauthors = Johnson EM |title=Spokane, Washington, sues Monsanto over PCBs in polluted state river|url=http://www.washingtontimes.com/news/2015/aug/3/spokane-sues-monsanto-over-spokane-river-contamina/|access-date=23 September 2015|agency=Reuters|date=August 4, 2015}}</ref><ref>{{cite news| vauthors = Payton M |title=City of San Diego Sues Monsanto Over PCB Pollution|url=http://www.nbcsandiego.com/news/local/City-of-San-Diego-Sues-Monsanto-Over-PCB-Pollution-322446342.html|access-date=22 August 2015|publisher=NBC 7 San Diego|date=21 August 2015}}</ref>

In July 2015, a St Louis county court in Missouri found that Monsanto, Solutia, Pharmacia and Pfizer were not liable for a series of deaths and injuries caused by PCBs manufactured by [[Monsanto Chemical Company]] until 1977. The trial took nearly a month and the jury took a day of deliberations to return a verdict against the plaintiffs from throughout the USA.<ref>{{cite web|url=http://www.stltoday.com/business/local/monsanto-pcb-lawsuit-set-to-begin-in-st-louis-county/article_a5101269-fa99-520c-88c5-325ffa80ec16.html|title=Monsanto PCB lawsuit set to begin in St. Louis County|publisher=St Louis Post-Despatch| vauthors = Barker T |date=11 June 2015|access-date=29 August 2015}}</ref><ref>{{cite web|url=http://www.stltoday.com/business/local/monsanto-prevails-in-pcb-lawsuit/article_9a5699ef-f545-5ad2-8f67-624f78fb10b7.html|title=Monsanto prevails in PCB lawsuit|publisher=St Louis Post-Despatch| vauthors = Barker T |date=7 July 2015|access-date=12 July 2020}}</ref> Similar cases are ongoing. "The evidence simply doesn't support the assertion that the historic use of PCB products was the cause of the plaintiffs' harms. We are confident that the jury will conclude, as two other juries have found in similar cases, that the former Monsanto Company is not responsible for the alleged injuries," a Monsanto statement said.<ref>{{cite news| vauthors = Barker T |title=Monsanto faces another PCB trial in St. Louis|url=http://www.stltoday.com/business/local/monsanto-faces-another-pcb-trial-in-st-louis/article_d5f46e4b-0631-5a92-8fbb-cd814ac19f13.html|access-date=12 July 2020|publisher=St Louis Post-Dispatch|date=October 1, 2015}}</ref>

In May 2016, a Missouri state jury ordered Monsanto to pay $46.5 million to three plaintiffs whose exposure to PCB caused non-Hodgkin lymphoma.<ref>{{cite news| vauthors = Currier J |title=St. Louis jury orders Monsanto to pay $46.5 million in latest PCB lawsuit|url=http://www.stltoday.com/news/local/metro/st-louis-jury-orders-monsanto-to-pay-million-in-latest/article_08e25795-0d36-5155-999c-c6bd954a6c2e.html|access-date=13 December 2016|newspaper=St. Louis Post-Dispatch|date=May 26, 2016}}</ref><ref>{{cite web | vauthors = Parker S |title=Monsanto Plans $280M for PCB Personal Injury Settlements |url= http://www.law360.com/articles/848456/monsanto-plans-280m-for-pcb-personal-injury-settlements |website=Law360.com|publisher=Law360|access-date=20 July 2020}}</ref>

In December 2016, the state of Washington filed suit in King County. The state sought damages and clean up costs related to PCBs.<ref>{{Cite press release | url=http://www.atg.wa.gov/news/news-releases/ag-ferguson-makes-washington-first-state-sue-monsanto-over-pcb-damages-cleanup | title=AG Ferguson makes Washington first state to sue Monsanto over PCB damages, cleanup cost |date=8 Dec 2016 |publisher=Washington State Office of the Attorney General}}</ref><ref>{{cite web|url=http://agportal-s3bucket.s3.amazonaws.com/uploadedfiles/Another/News/Press_Releases/WA_Complaint_FINALnew.pdf |archive-url=https://web.archive.org/web/20170217143609/http://agportal-s3bucket.s3.amazonaws.com/uploadedfiles/Another/News/Press_Releases/WA_Complaint_FINALnew.pdf |archive-date=2017-02-17 |url-status=live|title=State of Washington v. Monsanto Company, Solutia Inc. and Pharmacia Corporation|website=Agportal-s3bucket.s3.amazonaws.com|access-date=June 26, 2022}}</ref> In March 2018 [[Ohio Attorney General]] [[Mike DeWine]] also filed a lawsuit against [[Monsanto]] over health issues posed by PCBs.<ref>{{cite web | url=https://www.nbcnews.com/news/us-news/monsanto-concealed-effects-toxic-chemical-decades-ohio-ag-alleges-n853866|date=March 6, 2018 |first=Tim |last= Stelloh| title=Monsanto concealed effects of toxic chemical for decades, Ohio AG says in suit| website=[[NBC News]]}}</ref>

On November 21, 2019, a federal judge denied a bid by Monsanto to dismiss a lawsuit filed by LA County calling the company to clean up cancer-causing PCBs from Los Angeles County waterways and storm sewer pipelines.<ref name=lacounty>{{cite news|url=https://www.courthousenews.com/judge-advances-la-countys-spat-with-monsanto-over-pcbs-cleanup/|title=Judge Advances LA County's Spat With Monsanto Over PCB Cleanup|author=Martin Macias Jr |newspaper=Courthouse News Service|access-date=June 26, 2022}}</ref> The lawsuit calls for Monsanto to pay for cleanup of PCBs from dozens of waterways, including the LA River, San Gabriel River and the Dominguez Watershed.<ref name=lacounty />

In June 2020, Bayer agreed to pay $650 million to settle local lawsuits related to Monsanto's pollution of public waters in various areas of the United States with PCBs.<ref>{{cite news |title=Monsanto settles with over 200 exposed to chemicals in WA school |url=https://www.seattletimes.com/seattle-news/times-watchdog/pcb-maker-settles-with-more-than-200-exposed-to-toxicant-at-monroe-school/ |work=The Seattle Times |date=21 August 2025 |archive-url=https://archive.today/20250821140547/https://www.seattletimes.com/seattle-news/times-watchdog/pcb-maker-settles-with-more-than-200-exposed-to-toxicant-at-monroe-school/ |archive-date=21 August 2025}}</ref><ref>{{cite news |last1=Chappell |first1=Bill |title=Bayer To Pay More Than $10 Billion To Resolve Cancer Lawsuits Over Weedkiller Roundup |url=https://www.npr.org/2020/06/24/882949098/bayer-to-pay-more-than-10-billion-to-resolve-roundup-cancer-lawsuits |work=NPR |date=24 June 2020 |archive-url=https://archive.today/20230201211441/https://www.npr.org/2020/06/24/882949098/bayer-to-pay-more-than-10-billion-to-resolve-roundup-cancer-lawsuits |archive-date=1 February 2023 |language=en}}</ref>


In that same month of June 2020, Attorney General Bob Ferguson announced Monsanto will pay 95 million dollar settlement after the 3 year litigation. This litigation began related to the costs of water contamination. PCB contamination is found in 13 bodies of water, where fish advisory warnings have been given from the PCBs that have accumulated in the tissues. Some of the consequences, include affecting other aspects of the ecosystem, such as contamination on bays, soil and other related species like birds and other animal life.<ref>{{cite web |title=Monsanto to pay record $95 million to end Ferguson's lawsuit over PCBs {{!}} Washington State |url=https://www.atg.wa.gov/news/news-releases/monsanto-pay-record-95-million-end-ferguson-s-lawsuit-over-pcbs |website=Office of Attorney General |publisher=Washington State |archive-url=https://archive.today/20250907194012/https://www.atg.wa.gov/news/news-releases/monsanto-pay-record-95-million-end-ferguson-s-lawsuit-over-pcbs |archive-date=September 7, 2025}}</ref>

In 2023, over 90 Vermont school districts joined a lawsuit against Monsanto alleging that PCBs created by the company were used in the construction of their schools. The [[Vermont Attorney General]]'s office also filed its own lawsuit against Monsanto related to the use of its PCBs.<ref>{{cite news |work=[[Seven Days (newspaper)|Seven Days]] |access-date=4 July 2023 |last=Novak |first=Alison |date=30 June 2023 |url=https://www.sevendaysvt.com/vermont/more-than-90-vermont-school-districts-sue-monsanto-over-pcbs/Content?oid=38563024 |title=More Than 90 Vermont School Districts Sue Monsanto Over PCBs}}</ref>

A settlement between Monsanto and students, parents and staff of Monroe school occurred in August 2025. The legal campaign started in 2018, where the plaintiffs alleged Monsanto knew about the toxicity of PCBs that were used in the school infrastructure. Not only did the school not remove the banned material to ensure safety of students, but Monsanto themselves knew of the health implications of PCBs before they were banned.<ref>{{cite news |last1=Ramadan |first1=Lulu |title=Monsanto settles with over 200 exposed to chemicals in WA school |url=https://www.seattletimes.com/seattle-news/times-watchdog/pcb-maker-settles-with-more-than-200-exposed-to-toxicant-at-monroe-school/ |work=The Seattle Times |date=21 August 2025}}</ref>

Further controversy occurred because evidence obtained by the Washington state who is in an ongoing legal battle with Monsanto shows that they knew of the risks of PCBs before the 1979 ban, based on over 20,000 internal documents.<ref>{{cite news |last1=Neslen |first1=Arthur |title=Monsanto sold banned chemicals for years despite known health risks, archives reveal |url=https://www.theguardian.com/environment/2017/aug/09/monsanto-continued-selling-pcbs-for-years-despite-knowing-health-risks-archives-reveal |work=The Guardian |date=10 August 2017}}</ref>

In October 2025, NC state university filed a lawsuit against Monsanto over PCBs used in construction of Poe Hall on campus in 1971. The National Institute for Occupational Safety and Health is currently evaluating the health hazards.<ref>{{cite news |last1=Eanes |first1=Zachery |title=N.C. State sues Monsanto over toxic Poe Hall chemicals |url=https://www.axios.com/local/raleigh/2025/10/01/nc-state-sues-monsanto-over-toxic-poe-hall-chemicals |work=Axios |date=1 October 2025 |language=en}}</ref><ref>{{cite web |title=NC State Monsanto Complaint Filed |url=https://generalcounsel.ncsu.edu/wp-content/uploads/sites/263/2025/10/2025-10-01-NC-State-Monsanto-Complaint-FILED.pdf |website=Office of General Counsel |publisher=NC State University}}</ref>

==History==
[[File:CP-SLOPE-wb-gantry-power-supply-transformer-wiki.JPG|thumb|Old power transformers are a major source of PCBs. Even units not originally filled with PCB may be contaminated, since PCB and oil mix freely and any given transformer may have been refilled from hoses or tanks also used with PCBs.]]
In 1865, the first "PCB-like" chemical was discovered, and was found to be a byproduct of [[coal tar]]. Years later in 1876, German chemist [[Oscar Döbner]] (Doebner) synthesized the first PCB in a laboratory.<ref>{{cite journal |title=Constitution der Diphenyldisulfosäure und ihrer Umwandlungsprodukte |journal=Berichte der Deutschen Chemischen Gesellschaft |vauthors=Doebner OG |year=1876 |volume=9 |issue=1 |pages=129–131|doi= 10.1002/cber.18760090139}}</ref> Since then, large amounts of PCBs were released into the environment, to the extent that there are even measurable amounts of PCBs in feathers of birds currently held in museums before the production of PCBs peaked.<ref>{{cite book |vauthors=Riseborough R, Brodine V |chapter=More Letters in the Wind | veditors=Novick S, Cottrell D |title=Our world in peril: an Environment review |location=Greenwich, CT |publisher=Fawcett |year=1971 |pages=243–55}}</ref>

In 1935, [[Monsanto Company|Monsanto Chemical Company]] (later [[Solutia Inc]]) took over commercial production of PCBs from [[Swann Chemical Company]] which had begun in 1929. PCBs, originally termed "chlorinated diphenyls", were commercially produced as mixtures of [[isomer]]s at different degrees of chlorination. The electric industry used PCBs as a non-flammable replacement for [[mineral oil]] to cool and insulate industrial transformers and capacitors. PCBs were also commonly used as [[heat stabilizer]] in cables and electronic components to enhance the heat and [[Fireproofing|fire resistance]] of PVC.<ref>{{cite book|title=Health Concerns and Environmental Issues with PVC-Containing Building Materials in Green Buildings | vauthors = Kaley KB, Carlisle J, Siegel D, Salinas J |publisher=Integrated Waste Management Board, California Environmental Protection Agency |date=October 2006 |page=11 |url=http://www.ciwmb.ca.gov/publications/GreenBuilding/43106016.pdf |access-date=2007-08-03 |archive-url=https://web.archive.org/web/20070715221107/http://www.ciwmb.ca.gov/Publications/GreenBuilding/43106016.pdf |archive-date=July 15, 2007 }}</ref>

In the 1930s, the toxicity associated with PCBs and other chlorinated hydrocarbons, including [[polychlorinated naphthalene]]s, was recognized because of a variety of industrial incidents.<ref>{{cite journal |title= The problem of possible systemic effects from certain chlorinated hydrocarbons |journal= Journal of Industrial Hygiene and Toxicology | vauthors = Drinker CK, Warren MF, Bennett GA |year= 1937 |volume= 19 |issue= 7 |pages= 283–311}}</ref> Between 1936 and 1937, there were several medical cases and papers released on the possible link between PCBs and its detrimental health effects. In 1936, a U.S. [[Public health]] Service official described the wife and child of a worker from the Monsanto Industrial Chemical Company who exhibited [[blackhead]]s and [[pustule]]s on their skin. The official attributed these symptoms to contact with the worker's clothing after he returned from work. In 1937, a conference about the hazards was organized at [[Harvard School of Public Health]], and a number of publications referring to the toxicity of various chlorinated hydrocarbons were published before 1940.<ref>{{cite journal | vauthors = Butler DA |year=2005 |title=Connections: The Early History of Scientific and Medical Research on 'Agent Orange' |journal=Journal of Law and Policy |volume=13 |issue=2 |pages=527–542 |url= http://www.bluewaternavy.org/History%20of%20Agent%20Orange_butler.pdf |archive-url=https://web.archive.org/web/20100923050959/http://bluewaternavy.org/History%20of%20Agent%20Orange_butler.pdf |archive-date=2010-09-23}}</ref>

In 1947, Robert Brown reminded chemists that Arochlors were "objectionably toxic": "Thus the maximum permissible concentration for an 8-hr. day is 1 mg. per cu.m. [{{cvt|1|mg/m3|mg/m3|disp=out}}] of air. They also produce a serious and disfiguring [[dermatitis]]".<ref>{{cite journal | vauthors = Brown RM |title= The toxicity of the 'Arochlors' |journal= Chemist-Analyst |volume= 36 |page= 33 |year= 1947 |url=http://chemport.cas.org/cgi-bin/sdcgi?APP=ftslink&action=reflink&origin=npg&version=1.0&coi=1:CAS:528:DyaH2sXjs1WntA%3D%3D&pissn=0028-0836&pyear=1967&md5=58285ba11405fbe2e87bf46712d4f63d}}</ref>

In 1954, Kanegafuchi Chemical Co. Ltd. ([[Kaneka Corporation]]) first produced PCBs, and continued until 1972.<ref name="unep"/>{{page needed|date=October 2015}}

Through the 1960s Monsanto Chemical Company knew increasingly more about PCBs' harmful effects on humans and the environment, per internal leaked documents released in 2002, yet PCB manufacture and use continued with few restraints until the 1970s.<ref>{{cite news |title=Monsanto Hid Decades Of Pollution; PCBs Drenched Ala. Town, But No One Was Ever Told |newspaper=The Washington Post |date=January 1, 2002 |vauthors=Grunwald M |url=https://www.commondreams.org/headlines02/0101-02.htm |access-date=January 31, 2018 |archive-date=April 30, 2019 |archive-url=https://web.archive.org/web/20190430062759/https://www.commondreams.org/headlines02/0101-02.htm }}</ref>

In 1966, PCBs were determined by Swedish chemist Sören Jensen to be an environmental contaminant.<ref>{{cite journal | vauthors = Jensen S |title=Report of a new chemical hazard |journal=New Scientist |volume=32|page=612 |year=1966}}</ref> Jensen, according to a 1994 article in ''[[Sierra (magazine)|Sierra]]'', named chemicals PCBs, which previously, had simply been called "phenols" or referred to by various trade names, such as Aroclor, Kanechlor, Pyrenol, Chlorinol and others. In 1972, PCB production plants existed in Austria, [[West Germany]], France, the UK, Italy, Japan, Spain, the USSR and the US.<ref name="unep" />{{page needed|date=October 2015}}

In the early 1970s, Ward B. Stone of the [[New York State Department of Environmental Conservation]] (NYSDEC) first published his findings that PCBs were leaking from transformers and had contaminated the soil at the bottom of utility poles.

There have been allegations that [[Industrial Bio-Test Laboratories#Polychlorinated biphenyls|Industrial Bio-Test Laboratories]] engaged in data falsification in testing relating to PCBs.<ref>{{cite magazine |title=Pandora's poison |magazine=Sierra |date=September–October 1994 | vauthors = Coppolino EF | veditors = Rauber P, Lanner H, Shawley B |editor-link=Paul Rauber |volume=79 |issue=5 |page=40 |url=http://www.sierraclub.org/sierra/200103/conspiracy.asp |access-date=2012-07-12 |archive-url=https://web.archive.org/web/20090620074809/http://www.sierraclub.org/sierra/200103/conspiracy.asp |archive-date=2009-06-20 }}</ref><ref>{{cite book | vauthors = Robin MM |title=The World According to Monsanto: Pollution, Corruption, and the Control of the World's Food Supply |chapter=PCBs: White-Collar Crime |publisher=The New Press |year=2010 |page=22 |isbn=978-1-59558-426-7}}</ref><ref>{{cite news | vauthors = Jon J, Thomas P |title=Burying The Truth, the original Ecologist investigation into Monsanto and Brofiscin Quarry |date=2007-10-11 |url=http://www.theecologist.org/The_Brofiscin_Monsanto_Files/777777/burying_the_truth.html |work=The Ecologist |access-date=2012-07-16}}</ref><ref>{{cite news | vauthors = Steyer R |title=Lab Falsified Monsanto PCB Data, Witness Says |date=1991-10-29 |work=St. Louis Post-Dispatch}}</ref> In 2003, Monsanto and [[Solutia Inc.]], a Monsanto corporate spinoff, reached a US$700&nbsp;million settlement with the residents of [[Anniston, Alabama|West Anniston]], Alabama, who had been affected by the manufacturing and dumping of PCBs.<ref name="The New York Times" /><ref name=Alabama>{{cite web |url=http://www.legalnewsline.com/news/236012-ala.-sc-makes-ruling-in-cases-over-300m-monsanto-settlement |title=Ala. SC makes ruling in cases over $300M Monsanto settlement |publisher=Legal Newsline |date=May 1, 2012 |archive-url=https://web.archive.org/web/20131006060813/http://legalnewsline.com/news/236012-ala.-sc-makes-ruling-in-cases-over-300m-monsanto-settlement |archive-date=October 6, 2013}}</ref> In a trial lasting six weeks, the jury found that "Monsanto had engaged in outrageous behavior, and held the corporations and its corporate successors liable on all six counts it considered – including negligence, nuisance, wantonness and suppression of the truth."<ref name="60 Minutes CBS News" />

Existing products containing PCBs which are "totally enclosed uses" such as insulating fluids in transformers and capacitors, [[vacuum pump]] fluids, and [[hydraulic fluid]], are allowed to remain in use in the US.<ref>{{cite web |title=SUNY Dorm Tests Toxic |first=Eric |last=Francis |publisher= Planet Waves |orig-date=21 July 1994|url=http://dioxindorms.com/content/SUNY.html|work=Woodstock Times|access-date=9 June 2016}}</ref> The public, legal, and scientific concerns about PCBs arose from research indicating they are likely [[carcinogen]]s having the potential to adversely impact the environment and, therefore, undesirable as commercial products. Despite active research spanning five decades, extensive regulatory actions, and an effective ban on their production since the 1970s, PCBs still persist in the environment and remain a focus of attention.<ref name="unep" />{{page needed|date=October 2015}}

==Pollution due to PCBs==
===Belgium===
In 1999, the [[Dioxin Affair]] occurred when 50&nbsp;kg of PCB transformer oils were added to a stock of recycled fat used for the production of 500 tonnes of animal feed, eventually affecting around 2,500 farms in several countries.<ref>{{cite journal | vauthors = Bernard A, Broeckaert F, De Poorter G, De Cock A, Hermans C, Saegerman C, Houins G |display-authors=3| title = The Belgian PCB/dioxin incident: analysis of the food chain contamination and health risk evaluation | journal = Environmental Research | volume = 88 | issue = 1 | pages = 1–18 | date = January 2002 | pmid = 11896663 | doi = 10.1006/enrs.2001.4274 | bibcode = 2002ER.....88....1B }}</ref><ref name="Covaci">{{cite journal | vauthors = Covaci A, Voorspoels S, Schepens P, Jorens P, Blust R, Neels H |display-authors=3| title = The Belgian PCB/dioxin crisis-8 years later An overview | journal = Environmental Toxicology and Pharmacology | volume = 25 | issue = 2 | pages = 164–170 | date = March 2008 | pmid = 21783853 | doi = 10.1016/j.etap.2007.10.003 | bibcode = 2008EnvTP..25..164C }}</ref> The name ''Dioxin Affair'' was coined from early misdiagnosis of dioxins as the primary contaminants, when in fact they turned out to be a relatively small part of the contamination caused by thermal reactions of PCBs. The PCB congener pattern suggested the contamination was from a mixture of Aroclor 1260 and 1254. Over 9 million chickens, and 60,000 pigs were destroyed because of the contamination. The extent of human health effects has been debated, in part because of the use of differing risk assessment methods. One group predicted increased cancer rates, and increased rates of neurological problems in those exposed as neonates. A second study suggested carcinogenic effects were unlikely and that the primary risk would be associated with developmental effects due to exposure in pregnancy and neonates.<ref name="Covaci" /> Two businessmen who knowingly sold the contaminated feed ingredient received two-year suspended sentences for their role in the crisis.<ref>{{cite web|title=Dioxin scandal: 2 year suspended prison sentence|url=http://www.expatica.com/be/news/country-news/Dioxin-scandal-2-year-suspended-prison-sentence_158523.html|website=www.expatica.com|access-date=9 June 2016|date=2009-02-05|archive-date=2016-01-02|archive-url=https://web.archive.org/web/20160102025210/http://www.expatica.com/be/news/country-news/Dioxin-scandal-2-year-suspended-prison-sentence_158523.html}}</ref>

===Italy===
The Italian company Caffaro, located in [[Brescia]], specialized in producing PCBs from 1938 to 1984, following the acquisition of the exclusive rights to use the patent in Italy from Monsanto.<ref>{{Cite web |date=2016-05-11 |title=Effetto PCB |url=http://www.faustosalvi.net/en/portfolio/effetto-pcb/ |access-date=2022-06-17 |website=Fausto Salvi |language=en-US}}</ref> The pollution resulting from this factory and the case of Anniston, in the US, are the largest known cases in the world of PCB contamination in water and soil, in terms of the amount of toxic substance dispersed, size of the area contaminated, number of people involved and duration of production.

The values reported by the local health authority (ASL) of Brescia since 1999 are 5,000 times above the limits set by Ministerial Decree 471/1999 (levels for residential areas, 0.001&nbsp;mg/kg). As a result of this and other investigations, in June 2001, a complaint of an environmental disaster was presented to the Public Prosecutor's Office of Brescia. Research on the adult population of Brescia showed that residents of some urban areas, former workers of the plant, and consumers of contaminated food, have PCB levels in their bodies that are in many cases 10–20 times higher than reference values in comparable general populations.<ref>{{cite journal | vauthors = Turrio-Baldassarri L, Abate V, Battistelli CL, Carasi S, Casella M, Iacovella N, Indelicato A, La Rocca C, Scarcella C, Alivernini S | display-authors = 3 | title = PCDD/F and PCB in human serum of differently exposed population groups of an Italian city | journal = Chemosphere | volume = 73 | issue = 1 Suppl | pages = S228–S234 | date = August 2008 | pmid = 18514762 | doi = 10.1016/j.chemosphere.2008.01.081 | bibcode = 2008Chmsp..73S.228T }}</ref>{{medical citation needed|date=May 2015}} PCBs entered the human food supply by animals grazing on contaminated pastures near the factory, especially in local veal mostly eaten by farmers' families.<ref>{{cite journal | vauthors = La Rocca C, Mantovani A | title = From environment to food: the case of PCB | journal = Annali dell'Istituto Superiore di Sanità | volume = 42 | issue = 4 | pages = 410–416 | date = 2006 | pmid = 17361063 }}</ref> The exposed population showed an elevated risk of [[Non-Hodgkin lymphoma]], but not for other specific cancers.<ref>{{cite journal | vauthors = Zani C, Toninelli G, Filisetti B, Donato F | title = Polychlorinated biphenyls and cancer: an epidemiological assessment | journal = Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews | volume = 31 | issue = 2 | pages = 99–144 | date = 2013 | pmid = 23672403 | doi = 10.1080/10590501.2013.782174 | bibcode = 2013JESHC..31...99Z | s2cid = 5294247 }}</ref>

===Japan===
In 1968, a mixture of dioxins and PCBs got into rice bran oil produced in northern [[Kyushu]]. Contaminated cooking oil sickened more than 1,860 people. The symptoms were called [[Yushō disease]].<ref name="Aoki">{{cite journal | vauthors = Aoki Y | title = Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans as endocrine disrupters—what we have learned from Yusho disease | journal = Environmental Research | volume = 86 | issue = 1 | pages = 2–11 | date = May 2001 | pmid = 11386736 | doi = 10.1006/enrs.2001.4244 | bibcode = 2001ER.....86....2A }}</ref>

In Okinawa, high levels of PCB contamination in soil on [[Kadena Air Base]] were reported in 1987 at thousands of parts per million, some of the highest levels found in any pollution site in the world.<ref>{{cite web|title=U.S. military report suggests cover-up over toxic pollution in Okinawa|url=http://www.japantimes.co.jp/community/2014/03/17/issues/u-s-military-report-suggests-cover-up-over-toxic-pollution-in-okinawa/|website=The Japan Times|access-date=2016-06-09| vauthors = Mitchell J |date=March 17, 2014}}</ref>

===Republic of Ireland===
{{Main|2008 Irish pork crisis}}
In December 2008, a number of Irish news sources reported testing had revealed "extremely high" levels of dioxins, by [[toxic equivalent]], in pork products, ranging from 80 to 200 times the [[European Union|EU's]] upper safe limit of 1.5&nbsp;pg WHO-TEQ<sub>DFP</sub>/μg i.e. 0.12 to 0.3 parts per billion.<ref name="BBC PCB-1">{{cite news|title=Food body to meet on pork recall|url=http://news.bbc.co.uk/2/hi/uk_news/northern_ireland/7769871.stm|access-date=27 October 2014|work=BBC|publisher=BBC|date=7 December 2008}}</ref><ref>{{cite web |title=Commission Regulation (EC) No 1881/2006. Setting maximum levels for certain contaminants in foodstuffs |url=http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:364:0005:0024:EN:PDF|website=Official Journal of the European Union |publisher=European Union |location=Brussels |date=9 December 2006}}</ref>

[[Brendan Smith (politician)|Brendan Smith]], the Minister for Agriculture, Fisheries and Food, stated the pork contamination was caused by PCB-contaminated feed that was used on 9 of Ireland's 400 pig farms, and only one feed supplier was involved.<ref name="BBC PCB-1"/><ref>{{cite news|title=Firm at centre of toxin scare investigated|url=http://www.rte.ie/news/2008/1207/111373-pork/|access-date=27 October 2014|publisher=RTE news|date=9 December 2008}}</ref> Smith added that 38 beef farms also used the same contaminated feed, but those farms were quickly isolated and no contaminated beef entered the food chain.<ref>{{Cite news |title= Q&A: The recall of Irish pork |work= BBC |access-date= 2008-12-08 |date= 2008-12-07 |url= http://news.bbc.co.uk/2/hi/uk_news/7769893.stm}}</ref> While the contamination was limited to just 9 pig farms, the Irish government requested the immediate withdrawal and disposal of all pork-containing products produced in Ireland and purchased since September 1, 2008. This request for withdrawal of pork products was confirmed in a press release by the [[Food Safety Authority of Ireland]] on December 6.<!-- Not original press release cited, but that link was dead and this covers the topic in question --><ref>{{cite press release |title= Recall of Pork and Bacon Products December 2008 |publisher= Food Safety Authority of Ireland |date= December 2008 |url= http://www.fsai.ie/food_businesses/topics_of_interest/recall_of_pork_dec08/recall_information.html |access-date= 27 May 2013 |archive-url=https://web.archive.org/web/20130817023437/http://www.fsai.ie/food_businesses/topics_of_interest/recall_of_pork_dec08/recall_information.html |archive-date= 17 August 2013}}</ref>

It is thought that the incident resulted from the contamination of fuel oil used in a drying burner at a single feed processor, with PCBs. The resulting combustion produced a highly toxic mixture of PCBs, dioxins and [[furan]]s, which was included in the feed produced and subsequently fed to a large number of pigs.<ref>{{cite web |title= Report of the Inter-Agency Review Group on the Dioxin Contamination Incident in Ireland in December 2008 |publisher= Department of Agriculture, Food & the Marine |date= Dec 2009 |url= http://www.agriculture.gov.ie/media/migration/publications/2010/DioxinReport211209revised190110.pdf |access-date= 2010-09-02 |archive-date= 2010-12-09 |archive-url= https://web.archive.org/web/20101209121430/http://www.agriculture.gov.ie/media/migration/publications/2010/DioxinReport211209revised190110.pdf }}</ref>

===Kenya===
In Kenya, a number of cases have been reported in the 2010s of thieves selling [[transformer oil]], stolen from electric [[transformer]]s, to the operators of roadside [[food stall]]s for use in [[deep frying]]. When used for frying, it is reported that transformer oil lasts much longer than regular [[cooking oil]]. The downside of this misuse of the transformer oil is the threat to the health of the consumers, due to the presence of PCBs.<ref>{{cite web| vauthors = Iraki XN |title=Thieves fry Kenya's power grid for fast food|url=http://www.aljazeera.com/indepth/features/2014/12/thieves-fry-kenya-power-grid-fast-food-2014122884728785480.html|website=www.aljazeera.com|access-date=9 June 2016}}</ref>

===Slovakia===
The chemical plant Chemko in [[Strážske]] (east [[Slovakia]]) was an important producer of polychlorinated biphenyls for the former communist bloc ([[Comecon]]) until 1984. Chemko contaminated a large part of east Slovakia, especially the sediments of the [[Laborec]] river and [[reservoir]] [[Zemplínska šírava]].<ref>{{cite news |url=http://zivot.azet.sk/clanok/6399/viete-co-doma-dychate |title=Viete, čo doma dýchate? |trans-title=Do you know what you breathe at home? |language=sk |work=Život |issue=33 |year=2009 |vauthors=Himič D |access-date=2013-05-12 |archive-date=2014-10-27 |archive-url=https://web.archive.org/web/20141027043653/http://zivot.azet.sk/clanok/6399/viete-co-doma-dychate }}</ref><ref>{{cite web |url=http://www.greenpeace.org/slovakia/zataze/arealy-podnikov-a-priemyselne/projekt-implementacie |title=Chemko Strážske |archive-url=https://web.archive.org/web/20110516215920/http://www.greenpeace.org/slovakia/zataze/arealy-podnikov-a-priemyselne/projekt-implementacie |archive-date=May 16, 2011 |publisher=[[Greenpeace]] |language=sk}}</ref>

===Slovenia===
Between 1962 and 1983, the [[Iskra (company)|Iskra Kondenzatorji]] company in [[Semič]] ([[White Carniola]], Southeast [[Slovenia]]) manufactured [[capacitor]]s using PCBs. Due to the wastewater and improperly disposed waste products, the area (including the [[Krupa (Lahinja)|Krupa]] and [[Lahinja]] rivers) became highly contaminated with PCBs. The pollution was discovered in 1983, when the Krupa river was meant to become a water supply source. The area was sanitized then, but the soil and water are still highly polluted. Traces of PCBs were found in food (eggs, cow milk, walnuts) and Krupa is still the most PCB-polluted river in the world.

===Spain and Portugal===
Several [[cetacean]] species have very high mean [[blubber]] PCB concentrations likely to cause population declines and suppress population recovery. [[Striped dolphin]]s, [[bottlenose dolphin]]s and [[orca]]s were found to have mean levels that markedly exceeded all known marine mammal PCB toxicity thresholds. The western Mediterranean Sea and the south-west Iberian Peninsula were identified as "hotspots".<ref>{{cite journal | vauthors = Jepson PD, Deaville R, Barber JL, Aguilar À, Borrell A, Murphy S, Barry J, Brownlow A, Barnett J, Berrow S, Cunningham AA, Davison NJ, Ten Doeschate M, Esteban R, Ferreira M, Foote AD, Genov T, Giménez J, Loveridge J, Llavona Á, Martin V, Maxwell DL, Papachlimitzou A, Penrose R, Perkins MW, Smith B, de Stephanis R, Tregenza N, Verborgh P, Fernandez A, Law RJ | display-authors = 3 | title = PCB pollution continues to impact populations of orcas and other dolphins in European waters | journal = Scientific Reports | volume = 6 | article-number = 18573 | date = January 2016 | pmid = 26766430 | pmc = 4725908 | doi = 10.1038/srep18573 | bibcode = 2016NatSR...618573J }}</ref>

===United Kingdom===
[[Monsanto]] manufactured PCBs at its chemical plant in [[Newport, Wales|Newport]], South Wales, until the mid- to late-1970s. During this period, waste matter, including PCBs, from the Newport site was dumped at a disused quarry near [[Groes-faen]], west of [[Cardiff]], and Penhros landfill site<ref>{{cite news | url=http://www.walesonline.co.uk/news/wales-news/tip-fumes-felt-like-terror-2435122|title=Tip fumes "felt like terror attack"|author=<!--Not stated--> |date=June 30, 2004 |website=WalesOnline |publisher=Media Wales Ltd}}</ref> from where it continues to be released in waste water discharges.<ref>{{cite news | url= https://www.theguardian.com/environment/2011/feb/21/monsanto-brofiscin-pollution | title=Monsanto agrees to clean up toxic chemicals in South Wales quarry | date=21 February 2011 | access-date=16 September 2013 | vauthors = Levitt T | newspaper=The Guardian}}</ref>

===United States===<!-- Linked from [[PCBs in the United States]] redir. -->
Monsanto was the only company that manufactured PCBs in the US. Its production was entirely halted in 1977. (Kimbrough, 1987, 1995)<ref name=":2" /> On November 25, 2020, U.S. District Judge [[Fernando M. Olguin]] rejected a proposed $650 million settlement from Bayer, the company which acquired Monsanto in 2018, and allowed Monsanto-related lawsuits involving PCB to proceed.<ref>{{cite news|url=https://www.semissourian.com/story/2853810.html|title=Bayer's $650 Million PCB Pollution Settlement Rejected by Judge| vauthors = Rosenblatt J, Chediak M |publisher=Claims Journal|date=December 1, 2020|access-date=December 15, 2020}}{{dead link|date=June 2022|bot=medic}}{{cbignore|bot=medic}}</ref>

====Alabama====
PCBs originating from [[Monsanto Chemical Company]] in [[Anniston, Alabama|Anniston]], Alabama, were dumped into Snow Creek, which then spread to [[Choccolocco Creek]], then [[Logan Martin Lake]].<ref>{{cite web |title=Anniston PCB Site (Monsanto Co), Anniston, AL |url=https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0400123 |website=Superfund Site Profile |access-date=2020-05-24 |publisher=EPA |location=Atlanta, GA |archive-date=2016-12-27 |archive-url=https://web.archive.org/web/20161227015252/https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0400123 |url-status=live }}</ref> In the early 2000s, class action lawsuits were settled by local land owners, including those on Logan Martin Lake, and [[Lay Dam|Lay Reservoir]] (downstream on the [[Coosa River]]), for the PCB pollution. Donald Stewart, former Senator from Alabama, first learned of the concerns of hundreds of west Anniston residents after representing a church which had been approached about selling its property by Monsanto. Stewart went on to be the pioneer and lead attorney in the first and majority of cases against Monsanto and focused on residents in the immediate area known to be most polluted. Other attorneys later joined in to file suits for those outside the main immediate area around the plant; one of these was the late [[Johnnie Cochran]].

In 2007, the highest pollution levels remained concentrated in Snow and Choccolocco Creeks.<ref>{{cite journal | vauthors = Rypel AL, Findlay RH, Mitchell JB, Bayne DR | title = Variations in PCB concentrations between genders of six warmwater fish species in Lake Logan Martin, Alabama, USA | journal = Chemosphere | volume = 68 | issue = 9 | pages = 1707–1715 | date = August 2007 | pmid = 17490714 | doi = 10.1016/j.chemosphere.2007.03.046 | bibcode = 2007Chmsp..68.1707R }}</ref> Concentrations in fish have declined and continue to decline over time; sediment disturbance, however, can resuspend the PCBs from the sediment back into the water column and food web.

====California====

[[File:Fish Sign.png|thumb|Fish consumption advisory poster for San Francisco Bay]]

San Francisco Bay has been contaminated by PCBs, "a legacy of PCBs spread widely across the land surface of the watershed, mixed deep into the sediment of the Bay, and contaminating the Bay food web".<ref>{{Cite journal| doi = 10.1016/j.envres.2007.01.013| issn = 0013-9351| volume = 105| issue = 1| pages = 67–86| last1 = Davis| first1 = Jay| last2 = Hetzel| first2 = F.| last3 = Oram| first3 = J. J.| last4 = McKee| first4 = L. J.| title = Polychlorinated biphenyls (PCBs) in San Francisco Bay| journal = Environmental Research| series = Pollutants in the San Francisco Bay Estuary| access-date = 2023-04-27| date = 2007-09-01| pmid = 17451673| bibcode = 2007ER....105...67D| url = https://www.sciencedirect.com/science/article/pii/S0013935107000400| url-access = subscription}}</ref> Levels of PCBs in fish and shellfish exceed thresholds for safe consumption. Signs around the Bay warn anglers of which species to avoid. State water quality regulators set a [[Total Maximum Daily Load]] for PCBs require city and county governments around the Bay to implement control measures to limit PCBs in urban runoff.<ref>{{Cite conference| publisher = California Regional Water Quality Control Board, San Francisco Bay Region| page = 279| last = California Water Boards| title = Municipal Regional Stormwater NPDES permit. Order R2-2009-0074 NPDES Permit No. CAS612008 October 14, 2009| location = San Francisco| access-date = 2023-04-27| date = 2009-10-14| url = https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/phase1r2_2009_0074.pdf}}</ref> An important part of the second, revised version of this permit was the requirement for municipalities to install [[green infrastructure]] with a goal of reducing pollutant levels in stormwater.<ref>{{Cite conference| publisher = California Regional Water Quality Control Board, San Francisco Bay Region| page = 350| last = California Water Boards| title = Municipal Regional Stormwater NPDES permit. Order No. R2-2015-0049, NPDES Permit No. CAS612008| location = San Francisco| access-date = 2023-04-27| date = 2015-11-19| url = https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/stormwater/Municipal/R2-2015-0049.pdf}}</ref>

====Connecticut====
In [[New Haven]], the decommissioned [[English Station]] has a high concentration of PCB contamination due to the chemicals used in the running of the plant. This, along with [[asbestos]] contamination, has made cleaning and demolishing the abandoned site extremely difficult. The PCB contamination has spread to the soil, and to the river, where locals will sometimes fish unaware of the danger.<ref>{{cite web | vauthors = Leff L | title=Demolition Derailed; English Station In Limbo | website=New Haven Independent | date=19 August 2011 | url=https://www.newhavenindependent.org/index.php/archives/entry/english_station/ | access-date=2020-12-03}}</ref><ref>{{cite web | vauthors=Haar D | title=Dan Haar: English Station cleanup, at least a year away, should now wait for redevelopment | website=The Middletown Press | date=2019-08-25 | url=https://www.middletownpress.com/news/article/Dan-Haar-English-Station-cleanup-at-least-a-14374967.php | access-date=2020-12-03 | archive-date=2021-05-06 | archive-url=https://web.archive.org/web/20210506121936/https://www.middletownpress.com/news/article/Dan-Haar-English-Station-cleanup-at-least-a-14374967.php }}</ref><ref>{{cite web | vauthors = Chedekel L | title=State Orders Clean-Up Of English Station In New Haven | website=Connecticut Health Investigative Team | date=2013-04-11 | url=http://c-hit.org/2013/04/11/state-orders-clean-up-of-english-station-in-new-haven/ | access-date=2020-12-03}}</ref>

====Great Lakes====
In 1976, environmentalists found PCBs in the sludge at [[Waukegan, Illinois|Waukegan]] Harbor, the southwest end of [[Lake Michigan]]. They were able to trace the source of the PCBs back to the Outboard Marine Corporation that was producing boat motors next to the harbor. By 1982, the Outboard Marine Corporation was court-ordered to release quantitative data referring to their PCB waste released. The data stated that from 1954 they released 100,000 tons of PCB into the environment, and that the sludge contained PCBs in concentrations as high as 50%.<ref>{{cite book | vauthors = Ashworth W |title=The Late, Great Lakes |publisher=Wayne State University Press |year=1987 |isbn=978-0-8143-1887-4}}{{Page needed|date=May 2013}}</ref><ref>{{cite web| vauthors = Mahan ML |date=May 4, 1998 |title=Are PCBs still a problem in the great lakes? |url=http://www.cevl.msu.edu/~long/pcb.htm |archive-url=https://archive.today/20120722012319/http://www.cevl.msu.edu/~long/pcb.htm |archive-date=July 22, 2012 }}{{self-published source|date=May 2013}}</ref>{{self-published inline|date=May 2013}}

In 1989, during construction near the [[Zilwaukee, Michigan|Zilwaukee]] bridge, workers uncovered an uncharted landfill containing PCB-contaminated waste which cost $100,000 to clean up.<ref>{{cite web|url=http://www.michiganhighways.org/indepth/zilwaukee.html|title=Michigan Highways: In Depth: The Milwaukee Bridge | vauthors = Bessert CJ |work=michiganhighways.org}}</ref>

Much of the [[Great Lakes]] area were still heavily polluted with PCBs in 1988, despite extensive remediation work.<ref>{{cite journal | vauthors = Hileman B |title=Great Lakes Cleanup Effort |journal=Chemical and Engineering News |volume=66 |issue=6 |date=February 8, 1988 |pages=22–39 |doi=10.1021/cen-v066n006.p022}}</ref>

====Indiana====
From the late 1950s through 1977, [[Westinghouse Electric]] used PCBs in the manufacture of capacitors in its [[Bloomington, Indiana|Bloomington]], Indiana, plant. Reject capacitors were hauled and dumped in area salvage yards and landfills, including Bennett's Dump, Neal's Landfill and Lemon Lane Landfill.<ref name="US EPA"/> Workers also dumped PCB oil down factory drains, which contaminated the city sewage treatment plant.<ref>{{Cite web|url=http://copa.org/abb.html|access-date=2010-02-24|title=Westinghouse/ABB Plant Facility|year=2006|archive-date=2002-02-11|archive-url=https://web.archive.org/web/20020211012517/http://copa.org/abb.html}}</ref> The City of Bloomington gave away the sludge to area farmers and gardeners, creating anywhere from 200 to 2,000 sites, which remain unaddressed.

Over 1,000 tons of PCBs were estimated to have been dumped in [[Monroe County, Indiana|Monroe]] and [[Owen County, Indiana|Owen]] counties.{{Citation needed|date=May 2007}} Although federal and state authorities have been working on the sites' [[environmental remediation]], many areas remain contaminated. Concerns have been raised regarding the removal of PCBs from the [[karst]] limestone topography, and regarding the possible disposal options. To date, the Westinghouse Bloomington PCB Superfund site case does not have a Remedial Investigation/Feasibility Study (RI/FS) and Record of Decision (ROD), although Westinghouse signed a US Department of Justice Consent Decree in 1985.<ref name="US EPA">{{cite web|title=US EPA Region 5 Superfund|url=http://www.epa.gov/R5Super/npl/indiana/IND006418651.htm|archive-url=https://web.archive.org/web/19991109125026/http://www.epa.gov/R5Super/npl/indiana/IND006418651.htm|archive-date=November 9, 1999|access-date=2009-09-01}}</ref> The 1985 consent decree required Westinghouse to construct an incinerator that would incinerate PCB-contaminated materials. Because of public opposition to the incinerator, however, the State of Indiana passed a number of laws that delayed and blocked its construction. The parties to the consent decree began to explore alternative remedies in 1994 for six of the main PCB contaminated sites in the consent decree. Hundreds of sites remain unaddressed as of 2014. Monroe County will never be PCB-free, as noted in a 2014 Indiana University program about the local contamination.<ref name="US EPA" />

On February 15, 2008, Monroe County approved a plan to clean up the three remaining contaminated sites in the City of Bloomington, at a cost of [[United States dollar|$]]9.6 million to [[CBS Corporation|CBS Corp.]], the successor of Westinghouse. In 1999, Viacom bought CBS, so they are current responsible party for the PCB sites.<ref>{{cite web |title=Monroe Co. approves PCB clean up |url=http://www.indystar.com/apps/pbcs.dll/article?AID=/20080218/LOCAL/802180394 |publisher=IndyStar.com|access-date=2008-02-18 |archive-url=https://web.archive.org/web/20121022065825/http://www.indystar.com/apps/pbcs.dll/article?AID=/20080218/LOCAL/802180394 |archive-date=2012-10-22}}</ref>

====Massachusetts====
[[Pittsfield, Massachusetts|Pittsfield]], in western Massachusetts, was home to the [[General Electric Pittsfield Plant|General Electric (GE) transformer, capacitor, and electrical generating equipment divisions]]. The electrical generating division built and repaired equipment that was used to power the electrical utility grid throughout the nation. PCB-contaminated oil routinely migrated from GE's {{convert|254|acre|km2|adj=on}} industrial plant located in the very center of the city to the surrounding groundwater, nearby Silver Lake, and to the [[Housatonic River]], which flows through Massachusetts, Connecticut, and down to Long Island Sound.<ref name="GE Pittsfield-history">{{cite web |title=Site History & Description |website=GE/Housatonic River Site in New England |url=http://www.epa.gov/NE/ge/sitehistory.html |date=2011 |publisher=U.S. Environmental Protection Agency (EPA) |location=Boston, MA |archive-url=https://web.archive.org/web/20110519121339/http://www.epa.gov/NE/ge/sitehistory.html |archive-date=2011-05-19}}</ref> PCB-containing solid material was widely used as fill, including [[meander|oxbows]] of the Housatonic River. Fish and waterfowl which live in and around the river contain significant levels of PCBs and are not safe to eat.<ref>{{cite web |title=Rest of River of the GE-Pittsfield/Housatonic River Site |url=https://www.epa.gov/ge-housatonic/rest-river-ge-pittsfieldhousatonic-river-site |website=EPA Cleanups |date=2020-08-06 |publisher=EPA}}</ref> EPA designated the Pittsfield plant and several miles of the river as a [[Superfund]] site in 1997, and ordered GE to remediate the site. EPA and GE began a cleanup of the area in 1999.<ref name="GE Pittsfield-history"/>

[[New Bedford, Massachusetts#Geography|New Bedford Harbor]], which is a listed Superfund site,<ref name="EPA-New Bedford">{{cite web |title=General Information about the New Bedford Harbor Cleanup |url=https://www.epa.gov/new-bedford-harbor/general-information-about-new-bedford-harbor-cleanup |date=2020-09-15 |publisher=EPA}}</ref> contained some of the highest sediment concentrations of PCBs in the marine environment.<ref>{{cite web |url=http://www.darrp.noaa.gov/northeast/new_bedford/ |title=Case: New Bedford Harbor, MA |website=Damage Assessment, Remediation & Restoration Program |publisher=U.S. National Ocean Service |location=Silver Spring, MD |date=2009-10-19 |archive-url=https://web.archive.org/web/20100712092247/http://www.darrp.noaa.gov/northeast/new_bedford/|archive-date=2010-07-12 }}</ref> Cleanup of the area began in 1994 and is mostly complete as of 2020.<ref name="EPA-New Bedford"/>

Investigations into historic waste dumping in the [[Bliss Corner, Massachusetts|Bliss Corner]] neighborhood have revealed the existence of PCBs, among other hazardous materials, buried in soil and waste material.<ref>{{Cite web |url=https://www.mass.gov/service-details/bliss-corner-neighborhood-dartmouth-ma |title=Bliss Corner Neighborhood, Dartmouth, MA |website=Environmental Issues & Sites in Southeastern Massachusetts |publisher=Massachusetts Department of Environmental Protection |location=Lakeville, MA |access-date=2020-10-15}}</ref>

====Missouri====
In 1982, Martha C. Rose Chemical Inc. began processing and disposing of materials contaminated with PCBs in [[Holden, Missouri]], a small rural community about {{convert|40|mi}} east of Kansas City. From 1982 until 1986, nearly 750 companies, including General Motors Corp., Commonwealth Edison, Illinois Power Co. and West Texas Utilities, sent millions of pounds of PCB contaminated materials to Holden for disposal.<ref>{{Cite news|url=https://apnews.com/c83b34f4cdcddc21aff592829725dff4|title=Nearly a Decade After Spill, Cleanup of Toxic Site Drags On With PM-Rusted Legacy II|work=AP NEWS|access-date=2020-02-19}}</ref> Instead, according to prosecutors, the company began storing the contaminated materials while falsifying its reports to the EPA to show they had been removed. After investigators learned of the deception, Rose Chemical was closed and filed for bankruptcy. The site had become the nation's largest waste site for the chemical PCB.<ref>{{Cite web|url=https://apnews.com/4b94dd89b0231fd8df1ba7a512dcba42 |title=Lawmakers Warned That PCB Contamination Threatens Missouri Town|website=AP NEWS|access-date=2020-02-19}}</ref> In the four years the company was operational, the EPA inspected it four times and assessed $206,000 in fines but managed to collect only $50,000.<ref>{{Cite web |url= https://www.westword.com/news/a-dirty-shame-5058546 |title=A Dirty Shame| vauthors = Dexheimer E |date=1998-04-16|website=Westword|access-date=2020-02-20}}</ref>

After the plant closed the state environmental agency found PCB contamination in streams near the plant and in the city's sewage treatment sludge. A 100,000 square-foot warehouse and unknown amounts of contaminated soil and water around the site had to be cleaned up. Most of the surface debris, including close to 13 million pounds of contaminated equipment, carcasses and tanks of contaminated oil, had to be removed.<ref name=":1">{{Cite journal |vauthors=Steinzor RI |title=The lessons of Rose Chemical |journal=Public Power |volume=47|issue=2 |osti=5152472}}</ref> Walter C. Carolan, owner of Rose Chemical, and five others pleaded guilty in 1989 to committing fraud or falsifying documents. Carolan and two other executives served sentences of less than 18 months; the others received fines and were placed on probation. Cleanup costs at the site are estimated at $35 million.<ref name=":1" />

====Montana====
Two launch facilities at [[Malmstrom Air Force Base]] showed PCB levels higher than the thresholds recommended by the Environmental Protection Agency when extensive sampling began of active U.S. intercontinental ballistic missile bases to address specific cancer concerns in 2023.<ref>{{Cite news |last=Copp |first=Tara |date=2023-08-07 |title=Carcinogens found at Montana nuclear missile sites as reports of hundreds of cancers surface |url=https://apnews.com/article/missile-bases-cancer-air-force-malmstrom-military-1999fad70393f0d141676b7faa587eda |access-date=2023-08-08 |work=AP News |language=en}}</ref>

====New York====
[[Pollution of the Hudson River]] is largely due to dumping of PCBs by [[General Electric]] from 1947 to 1977. GE dumped an estimated 1.3 million pounds of PCBs into the Hudson River during these years. The PCBs came from the company's two capacitor manufacturing plants at [[Hudson Falls, New York|Hudson Falls]] and [[Fort Edward (town), New York|Fort Edward]], New York. This pollution caused a range of harmful effects to wildlife and people who eat fish from the river or drink the water.<ref>{{cite web|title=Hudson River Cleanup |publisher=EPA |url=https://www.epa.gov/hudsonriverpcbs/hudson-river-cleanup |date=2020-08-25}}</ref> In 1984, EPA declared a 200-mile (320&nbsp;km) stretch of the river, from Hudson Falls to New York City, to be a Superfund site requiring cleanup.<ref>{{cite web |title=Hudson River PCBs Superfund Site |url=https://www.epa.gov/superfund/superfund-success-stories-epa-region-2#hudson |website=Superfund Success Stories: EPA Region 2 |date=2018-06-04 |publisher=EPA}}</ref> Extensive remediation actions on the river began in the 1970s with the implementation of [[Clean Water Act#Point sources|wastewater discharge permits]] and consequent control or reduction of wastewater discharges, and sediment removal operations, which have continued into the 21st century.<ref>{{cite web |url=http://www.dec.ny.gov/lands/77105.html |title=How is the Hudson Doing? |website=Hudson River Estuary Program |publisher=New York State Department of Environmental Conservation |location=Albany, NY |access-date=2020-10-15 |archive-date=2017-11-19 |archive-url=https://web.archive.org/web/20171119075142/http://www.dec.ny.gov/lands/77105.html }}</ref>

[[Love Canal]] is a neighborhood in [[Niagara Falls, New York|Niagara Falls]], New York, that was heavily contaminated with toxic waste including PCBs.<ref>{{cite magazine | vauthors = Brown MH |title=Love Canal and the Poisoning of America |journal=The Atlantic |date=December 1979 |url=https://www.theatlantic.com/magazine/archive/1979/12/love-canal-and-the-poisoning-of-america/376297/}}</ref> [[Eighteen Mile Creek (Niagara County)|Eighteen Mile Creek]] in [[Lockport (town), New York|Lockport]], New York, is an EPA Superfund site for PCBs contamination.<ref>{{cite web |title= Superfund Site: Eighteen Mile Creek, Lockport, NY |url= https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0206456 | archive-url = https://web.archive.org/web/20170306235101/http://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0206456 | archive-date = 6 March 2017 |website=Superfund Program |url-status= live |publisher=EPA}}</ref>

PCB pollution at the [[Government Plaza, Binghamton|State Office Building]] in [[Binghamton, New York|Binghamton]] was responsible for what is now considered to be the first indoor environmental disaster in the United States.<ref>{{cite web | url = https://nypost.com/2011/08/07/former-ny-governor-hugh-carey-dead-at-92/ | title = Former NY governor Hugh Carey dead at 92 | work = New York Post | date = 7 August 2011 }}</ref> In 1981, a transformer explosion in the basement spewed PCBs throughout the entire 18-story building.<ref>{{cite report | title = Spill closes offices | work = Syracuse Herald-Journal | date = 5 February 1981 | page = D1 }}</ref> The contamination was so severe that cleanup efforts kept the building closed for 13 years.<ref>{{cite web | title = State Building Finally Reopens in Binghamton | url = https://buffalonews.com/news/state-building-finally-reopens-in-binghamton/article_fc156754-8eee-5d3a-9b79-e1f791b85250.html | work = The Buffalo News | date = 12 October 1994 }}</ref><ref>{{cite web | vauthors = Steinberg J | url = https://www.nytimes.com/1994/10/11/nyregion/13-year-cleaning-job-after-53-million-17-million-state-building-finally-declared.html?pagewanted=1 | title = The 13-Year Cleaning Job; After $53 Million, a $17 Million State Building Finally Is Declared Safe From Toxins | work = New York Times | date = 11 October 1994 }}</ref>

====North Carolina====
One of the largest deliberate PCB spills in American history occurred in the summer of 1978 when 31,000 gallons (117 m^3) of PCB-contaminated oil were illegally sprayed by the Ward PCB Transformer Company in {{convert|3|ft|m|adj=on}} swaths along the roadsides of some {{convert|240|mi|km}} of North Carolina highway shoulders in 14 counties and at the [[Fort Bragg]] Army Base. The crime, known as "[[Warren County PCB Landfill|the midnight dumpings]]", occurred over nearly two weeks, as drivers of a black-painted tanker truck drove down one side of rural Piedmont highways spraying PCB-laden waste and then up the other side the following night.<ref name="NY Times">{{cite web |url=https://www.nytimes.com/1982/08/11/us/carolinians-angry-over-pcb-landfill.html |title=Carolinians Angry Over PCB Landfill|work=NY Times |date=11 August 1982}}</ref>

Under Governor [[Jim Hunt|James B. Hunt]], Jr., state officials then erected large, yellow warning signs along the contaminated highways that read: "CAUTION: PCB Chemical Spills Along Highway Shoulders". The illegal dumping is believed to have been motivated by the passing of the [[Toxic Substances Control Act]] (TSCA), which became effective on August 2, 1978, and increased the expense of chemical waste disposal.

Within a couple of weeks of the crime, Robert Burns and his sons, Timothy and Randall, were arrested for dumping the PCBs along the roadsides. Burns was a business partner of Robert "Buck" Ward Jr., of the Ward PCB Transformer Company, in Raleigh. Burns and sons pleaded guilty to state and Federal criminal charges; Burns received a three to five-year prison sentence. Ward was acquitted of state charges in the dumping, but was sentenced to 18 months prison time for violation of TSCA.<ref name="NY Times" />

Cleanup and disposal of the roadside PCBs generated controversy, as the Governor's plan to pick up the roadside PCBs and to bury them in a landfill in rural [[Warren County, North Carolina|Warren County]] were strongly opposed in 1982 by local residents.<ref name="NY Times"/>

In October 2013, at the request of the South Carolina Department of Health and Environmental Control (SCDHEC), the City of [[Charlotte, North Carolina|Charlotte]], North Carolina, decided to stop applying [[biosolids|sewage sludge]] to land while authorities investigated the source of PCB contamination.<ref name="cmu">{{cite web| url=http://charmeck.org/city/charlotte/Utilities/AboutUs/Documents/Minutes%20October%202013.pdf |archive-url=https://web.archive.org/web/20140221223705/http://charmeck.org/city/charlotte/Utilities/AboutUs/Documents/Minutes%20October%202013.pdf |archive-date=2014-02-21 |url-status=live|author=Charlotte-Mecklenburg Utilities Advisory Committee|title=Charlotte-Mecklenburg Utilities Advisory Committee Minutes|date=October 17, 2013|page=3}}</ref>
In February 2014, the City of Charlotte admitted PCBs have entered their sewage treatment centers as well.<ref name="co214">{{cite news |url=http://www.charlotteobserver.com/2014/02/07/4670710/chemical-dumped-into-charlotte.html |title=Task force named to probe chemical dumping |date=7 February 2014 |newspaper=Charlotte Observer|archive-url=https://web.archive.org/web/20140213233743/https://www.charlotteobserver.com/2014/02/07/4670710/chemical-dumped-into-charlotte.html|archive-date=13 Feb 2014 |vauthors=Henderson B, Lyttle S, Bethea A}}</ref>

After the 2013 SCDHEC had issued emergency regulations,<ref>{{cite web|title=Emergency Regulation for Management of Wastewater System Sludge|url=http://www.scdhec.gov/Agency/docs/NewsReleaseDocs/PCBEmergencyRegFINAL.pdf|publisher=South Carolina Department of Health and Environmental Control|access-date=9 June 2016|archive-date=24 June 2016|archive-url=https://web.archive.org/web/20160624030305/http://www.scdhec.gov/Agency/docs/NewsReleaseDocs/PCBEmergencyRegFINAL.pdf}}</ref> the City of Charlotte discovered high levels of PCBs entering its sewage waste water treatment plants, where sewage is converted to sewage sludge.<ref name=co214/> The city at first denied it had a problem, then admitted an "event" occurred in February 2014, and in April that the problem had occurred much earlier.<ref name=cmu/><ref>{{cite news|url=http://www.charlotteobserver.com/2014/04/04/4817470/more-pcbs-found-in-charlotte-wastewater.html|title=More PCBs found in Charlotte wastewater, city says |date=4 April 2014| newspaper=Charlotte Observer|archive-url=https://web.archive.org/web/20151016075302/http://www.charlotteobserver.com/news/local/crime/article9109955.html|archive-date=16 Oct 2015|vauthors=Lyttle S}}</ref> The city stated that its very first test with a newly changed test method revealed very high PCB levels in its sewage sludge farm field fertilizer. Because of the widespread use of the contaminated sludge, SCDHEC subsequently issued PCB fish advisories for nearly all streams and rivers bordering farm fields that had been applied with city waste.<ref>{{cite web|url=http://www.scdhec.gov/Agency/NewsReleases/2014/nr20140703-01/|date=July 3, 2014|title=DHEC Releases Safe Fish Eating Advisory for S.C. Waters|website=scdhec.gov|publisher=South Carolina Department of Health and Environmental Control|access-date=February 4, 2015|archive-date=February 4, 2015|archive-url=https://web.archive.org/web/20150204180601/http://www.scdhec.gov/Agency/NewsReleases/2014/nr20140703-01/}}</ref>

====Ohio====
The [[Clyde cancer cluster]] (also known as the Sandusky County cancer cluster) is a [[childhood cancer|childhood]] [[cancer cluster]] that has affected many families in [[Clyde, Ohio|Clyde]], Ohio, and surrounding areas. PCBs were found in soil in a public park within the area of the cancer cluster.<ref>{{Cite news|url=http://www.toledoblade.com/news/state/2012/11/15/Toxic-sludge-discovered-at-park-in-Clyde-area-cancer-patients-families-shocked-lawyer-says/stories/20121115077|title='Toxic sludge' found at Clyde are park|newspaper=The Blade|language=en|access-date=2019-02-20|vauthors=Feehan J|date=15 Nov 2012}}</ref>

In [[Akron, Ohio|Akron]], Ohio, soil was contaminated and noxious PCB-laden fumes had been put into the air by an electrical transformer deconstruction operation from the 1930s to the 1960s.<ref>{{cite news | vauthors = Harper J |title=When PCBs, heavy metal spewed from smokestacks in southwest Akron: Toxic Remains |url=http://www.cleveland.com/akron/index.ssf/2015/12/when_pcbs_and_heavy_metal_spew.html|access-date=31 December 2015 |publisher=Cleveland.com|date=December 28, 2015}}</ref>

====South Carolina====
From 1955 until 1977, the Sangamo Weston plant in Pickens, South Carolina, used PCBs to manufacture capacitors, and dumped 400,000 pounds of PCB contaminated wastewater into the Twelve Mile Creek. In 1990, the EPA declared the {{convert|228|acre|km2}} site of the capacitor plant, its landfills and the polluted watershed, which stretches nearly {{convert|1,000|acre|km2}} downstream to Lake Hartwell as a [[Superfund]] site. Two dams on the Twelve Mile Creek are to be removed and on Feb. 22, 2011 the first of two dams began to be dismantled. Some contaminated sediment is being removed from the site and hauled away, while other sediment is pumped into a series of settling ponds.<ref>{{cite web | title = South Carolina NPL/NPL Caliber Cleanup Site Summaries; Sangamo Weston, Inc./Twelve-Mile Creek/Lake Hartwell PCB Contamination | url = http://www.epa.gov/region4/waste/npl/nplsc/sangamsc.htm | archive-url = https://web.archive.org/web/20061012115927/http://www.epa.gov/region4/waste/npl/nplsc/sangamsc.htm | archive-date = 12 October 2006 | work = USEPA }}</ref><ref>{{cite web | url = http://www.wyff4.com/r/26949154/detail.html | title = Dam Demolition Begins On Twelve Mile River | archive-url = https://web.archive.org/web/20110718123940/http://www.wyff4.com/r/26949154/detail.html | archive-date=2011-07-18 | work = WYFF News 4 | date = 22 February 2011 |vauthors=Muserallo S}}</ref>

In 2013, the state environmental regulators issued a rare emergency order, banning all [[sewage sludge]] from being land applied or deposited on landfills, as it contained very high levels of PCBs. The problem had not been discovered until thousands of acres of farm land in the state had been contaminated by the [[hazardous]] sludge. A criminal investigation to determine the perpetrator of this crime was launched.<ref>{{cite web |url=http://www.scdhec.gov/administration/news/2013/nr20130925-01.htm |title=DHEC: General Agency Information |date=2013 |work=scdhec.gov |access-date=2013-09-26 |archive-date=2013-09-26 |archive-url=https://web.archive.org/web/20130926153115/http://www.scdhec.gov/administration/news/2013/nr20130925-01.htm }}</ref>

====Washington====
As of 2015, several bodies of water in the state of Washington were contaminated with PCBs, including the [[Columbia River]], the [[Duwamish River]], [[Green Lake (Seattle)|Green Lake]], [[Lake Washington]], the [[Okanogan River]], [[Puget Sound]], the [[Spokane River]], the [[Walla Walla River]], the [[Wenatchee River]], and the [[Yakima River]].<ref>{{cite web |title=Fish Consumption Advisories | work = Washington State Dept. of Health |url=http://www.doh.wa.gov/CommunityandEnvironment/Food/Fish/Advisories |access-date=9 June 2016}}</ref> A study by Washington State published in 2011 found that the two largest sources of PCB flow into the Spokane River were City of Spokane stormwater (44%) and municipal and industrial discharges (20%).<ref>{{cite web |title=Spokane River PCB Source Assessment 2003–2007 |url=https://fortress.wa.gov/ecy/publications/documents/1103013.pdf |archive-url=https://web.archive.org/web/20151004144842/https://fortress.wa.gov/ecy/publications/documents/1103013.pdf |archive-date=2015-10-04 |url-status=live |access-date=9 June 2016}}</ref>

PCBs entered the environment through paint, hydraulic fluids, sealants, inks and have been found in river sediment and wildlife. Spokane utilities will spend $300 million to prevent PCBs from entering the river in anticipation of a 2017 federal deadline to do so.<ref>{{cite news | vauthors = Deshais N |title=Spokane sues Monsanto for PCB contamination |url=http://www.spokesman.com/stories/2015/aug/03/spokane-sues-monsanto-pcb-contamination/ |access-date=14 August 2015 |work=The Spokesman-Review|date=3 August 2015}}</ref> In August 2015 Spokane joined other U.S. cities like [[San Diego]] and [[San Jose, California|San Jose]], California, and [[Westport, Massachusetts|Westport]], Massachusetts, in seeking damages from Monsanto.<ref>{{cite news |agency=Associated Press |title=Spokane sues Monsanto over Spokane River contamination |url=http://www.seattletimes.com/seattle-news/spokane-sues-monsanto-over-spokane-river-contamination/ |access-date=14 August 2015 |work=Seattle Times |date=August 3, 2015}}</ref>

====Wisconsin====
From 1954 until 1971, the Fox River in [[Appleton, Wisconsin]], had PCBs deposited into it from Appleton Paper/NCR, P.H. Gladfelter, [[Georgia-Pacific]] and other notable local paper manufacturing facilities. The Wisconsin DNR estimates that after wastewater treatment the PCB discharges to the Fox River due to production losses ranged from 81,000&nbsp;kg to 138,000&nbsp;kg. (178,572&nbsp;lbs. to 304,235&nbsp;lbs). The production of Carbon Copy Paper and its byproducts led to the discharge into the river. Fox River clean up is ongoing.<ref>{{cite web | vauthors = Katers RL | date = |title=Sources of PCBs in the Fox River and Green Bay |url=http://www.foxriverwatch.com/pcb_pcbs_sources_1.html |website=www.foxriverwatch.com |access-date=9 June 2016 |archive-date=6 October 2014 |archive-url=https://web.archive.org/web/20141006234908/http://www.foxriverwatch.com/pcb_pcbs_sources_1.html }}</ref>

=== Pacific Ocean ===
Polychlorinated biphenyls have been discovered in organisms living in the [[Mariana Trench]] in the [[Pacific Ocean]]. Levels were as high as 1,900 nanograms per gram of [[Amphipoda|amphipod]] tissue in the organisms analyzed.<ref>{{Cite news|url=https://www.economist.com/news/science-and-technology/21716891-entrenched-nasty-chemicals-abound-what-was-thought-untouched-environment|title=Nasty chemicals abound in what was thought an untouched environment|newspaper=The Economist|access-date=2017-02-26|date=2017-02-18}}</ref>

==Regulation==
===Japan===
In 1972 the Japanese government banned the production, use, and import of PCBs.<ref name="unep"/>{{page needed|date=October 2015}}

===Sweden===
In 1973, the use of PCBs in "open" or "[[dissipative]]" sources (such as [[Plasticizer|plasticisers]] in paints and cements, casting agents, [[fire retardant]] fabric treatments and [[Heat stabilizer|heat stabilizing additives]] for PVC electrical insulation, [[adhesive]]s, paints and waterproofing, [[railroad tie]]s) was banned in Sweden.

===United Kingdom===
In 1981, the UK banned closed uses of PCBs in new equipment, and nearly all UK PCB synthesis ceased; closed uses in existing equipment containing in excess of 5&nbsp;litres of PCBs were not stopped until December 2000.<ref>{{cite web |title=Guidance on municipal waste strategies, Section 5.12 Equipment, which contains low volumes of PCBs |publisher=UK Department of the Environment, Transport and the Regions |page=17 |year=2001 |url=http://www.defra.gov.uk/environment/waste/management/guidance/mwms/pdf/mwms.pdf |access-date=2008-01-29 |archive-url=https://web.archive.org/web/20080414094248/http://www.defra.gov.uk/environment/waste/management/guidance/mwms/pdf/mwms.pdf |archive-date=2008-04-14}}</ref>

===United States===
In 1976, concern over the toxicity and persistence (chemical stability) of PCBs in the environment led the [[United States Congress]] to ban their domestic production, effective January 1, 1978, pursuant to the [[Toxic Substances Control Act of 1976|Toxic Substances Control Act]].<ref>United States. Toxic Substances Control Act. {{usc|15|2605}}. Approved October 11, 1976.</ref><ref>{{cite web |title=Summary of the Toxic Substances Control Act |date=2019-09-10 |publisher=United States Environmental Protection Agency (EPA) |location=Washington, D.C. |url=https://www.epa.gov/laws-regulations/summary-toxic-substances-control-act}}</ref> To implement the law, EPA banned new manufacturing of PCBs, but issued regulations that allowed for their continued use in electrical equipment for economic reasons.<ref>{{cite web | vauthors = Auer CM, Kover FD, Aidala JV, Greenwood M | url = http://www.epaalumni.org/hcp/toxics.pdf | title = Toxic Substances: A Half Century of Progress | work = EPA Alumni Association | date = March 2016 }}</ref> EPA began issuing regulations for PCB usage and disposal in 1979.<ref>{{cite web |title=EPA Bans PCB Manufacture; Phases Out Uses |date=1979-04-19 |id=Press Release |publisher=EPA |url=https://www.epa.gov/archive/epa/aboutepa/epa-bans-pcb-manufacture-phases-out-uses.html}}</ref> The agency has issued guidance publications for safe removal and disposal of PCBs from existing equipment.<ref>{{cite web |title=Policy and Guidance for Polychlorinated Biphenyl |url=https://19january2017snapshot.epa.gov/pcbs/policy-and-guidance-polychlorinated-biphenyl-pcbs_.html |date=2016-12-01 |publisher=EPA}}</ref>

EPA defined the "maximum contaminant level goal" for [[public water system]]s as zero, but because of the limitations of water treatment technologies, a level of 0.5 parts per billion is the actual regulated level ([[maximum contaminant level]]).<ref>{{cite web|title=National Primary Drinking Water Regulations |url=https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations |date=2020-02-14 |publisher=EPA}}</ref>

==Methods of destruction==
===Physical===
PCBs were technically attractive because of their inertness, which includes their resistance to combustion. Nonetheless, they can be effectively destroyed by [[incineration]] at 1000&nbsp;°C. When combusted at lower temperatures, they convert in part to more hazardous unintentional persistent organic pollutants, including polychlorinated dibenzofurans and dibenzo-p-dioxins. When conducted properly, the combustion products are water, carbon dioxide, and [[hydrogen chloride]]. In some cases, the PCBs are combusted as a solution in kerosene. PCBs have also been destroyed by pyrolysis in the presence of alkali metal [[carbonate]]s.<ref name=Ullmann/>

[[Thermal desorption]] is highly effective at removing PCBs from soil.<ref>{{cite journal | vauthors = Qi Z, Chen T, Bai S, Yan M, Lu S, Buekens A, Yan J, Bulmău C, Li X | display-authors = 3 | title = Effect of temperature and particle size on the thermal desorption of PCBs from contaminated soil | journal = Environmental Science and Pollution Research International | volume = 21 | issue = 6 | pages = 4697–4704 | date = March 2014 | pmid = 24352542 | doi = 10.1007/s11356-013-2392-4 | bibcode = 2014ESPR...21.4697Q | s2cid = 26156538 }}</ref>

===Chemical===
PCBs are fairly chemically unreactive, this property being attractive for its application as an inert material. They resist [[oxidation]].{{self-published inline|date=May 2013}}{{citation needed|date=April 2023}}
Many chemical compounds are available to destroy or reduce the PCBs. Commonly, PCBs are degraded by basic mixtures of [[glycol]]s, which displace some or all chloride. Also effective are reductants such as sodium or [[sodium naphthalene]].<ref name=Ullmann/> [[Vitamin B12]] has also shown promise.<ref>{{cite journal |doi=10.1021/es9804823 |title=Polychlorinated Biphenyl Reductive Dechlorination by Vitamin B12s: Thermodynamics and Regiospecificity |year=1999 | vauthors = Woods SL, Trobaugh DJ, Carter KJ |journal=Environmental Science & Technology |volume=33 |issue=6 |pages=857–863|bibcode=1999EnST...33..857W}}</ref>

===Microbial===
The use of [[microorganism]]s to degrade PCBs from contaminated sites, relying on multiple microorganisms' co-metabolism, is known as [[bioremediation of polychlorinated biphenyl]]. Some micro-organisms [[biodegradation|degrade]] PCBs by reducing the C-Cl bonds. Microbial dechlorination tends to be rather slow-acting in comparison to other methods. Enzymes extracted from microbes can show PCB activity. In 2005, ''[[Shewanella oneidensis]]'' biodegraded a high percentage of PCBs in soil samples.<ref>{{cite journal | vauthors = De Windt W, Aelterman P, Verstraete W | title = Bioreductive deposition of palladium (0) nanoparticles on Shewanella oneidensis with catalytic activity towards reductive dechlorination of polychlorinated biphenyls | journal = Environmental Microbiology | volume = 7 | issue = 3 | pages = 314–325 | date = March 2005 | pmid = 15683392 | doi = 10.1111/j.1462-2920.2005.00696.x | bibcode = 2005EnvMi...7..314W }}</ref> A low voltage current can stimulate the microbial degradation of PCBs.<ref>{{cite journal | vauthors = Chun CL, Payne RB, Sowers KR, May HD | title = Electrical stimulation of microbial PCB degradation in sediment | journal = Water Research | volume = 47 | issue = 1 | pages = 141–152 | date = January 2013 | pmid = 23123087 | pmc = 3508379 | doi = 10.1016/j.watres.2012.09.038 | bibcode = 2013WatRe..47..141C }}</ref>

===Fungal===
There is research showing that some [[ligninolytic fungi]] can degrade PCBs.<ref>{{cite journal | vauthors = Cvančarová M, Křesinová Z, Filipová A, Covino S, Cajthaml T |display-authors=3| title = Biodegradation of PCBs by ligninolytic fungi and characterization of the degradation products | journal = Chemosphere | volume = 88 | issue = 11 | pages = 1317–1323 | date = September 2012 | pmid = 22546633 | doi = 10.1016/j.chemosphere.2012.03.107 | bibcode = 2012Chmsp..88.1317C }}</ref>

==Bioremediation==
The remediation, or removal, of PCBs from estuarian and coastal river sediments is quite difficult due to the overlying water column and the potential for resuspension of contaminants during the removal process. The most common method of PCB extraction from sediments is to dredge an area and dispose of the sediments in a landfill. This method is troubling for a number of reasons, namely that it has a risk of resuspension of the chemicals as the sediments are disturbed, and this method can be very damaging to ecosystems.<ref>{{cite journal |last1=Eggleton |first1=Jacqueline |last2=Thomas |first2=Kevin |title=A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events |journal=Environment International |date=September 2004 |volume=30 |issue=7 |pages=973–980 |doi=10.1016/j.envint.2004.03.001 |pmid=15196845 |bibcode=2004EnInt..30..973E }}</ref>

A potential cost effective, low risk remediation technique is bioremediation. Bioremediation involves the use of biota to remediate sediments. Phytoremediation, the use of plants to remediate soils, has been found to be effective for a broad range of contaminants such as mercury, PCB, and PAHs in terrestrial soils.<ref>{{cite book |last1=McCutcheon |first1=Steven |last2=Schnoor |first2=Jerald |title=Phytoremediation: Transformation and Control of Contaminants |date=26 September 2003 |publisher=Wiley |location=New York |isbn=978-0-471-27304-2 |pages=1–58 }}</ref> A promising study conducted in New Bedford Harbor found that ''Ulva rigida'', a type of seaweed common throughout the world, is effective at removing PCB from sediments.<ref>{{cite journal |last1=Cheney |first1=Donald |last2=Rajic |first2=Ljiljana |last3=Sly |first3=Elizabeth |last4=Meric |first4=Dogus |last5=Sheahan |first5=Thomas |display-authors=3|title=Uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida |journal=Marine Pollution Bulletin |date=26 September 2014 |volume=88 |issue=1–2 |pages=207–214 |doi=10.1016/j.marpolbul.2014.09.004 |pmid=25261178 |bibcode=2014MarPB..88..207C }}</ref> During a typical bloom in New Bedford Harbor, ''U. rigida'' forms a thick mat that lies on top of and in contact with the sediment. This allows for ''U. rigida'' to uptake large amounts of PCB from the sediment with concentrations of PCB in ''U. rigida'' reaching 1580 μg kg<sup>−1</sup> within 24 hours of the bloom. Live tissue tended to take up higher concentrations of PCB than dead tissue, but this is not to say that dead tissue did not still take up large amounts of PCB as well.

==Homologs==
For a complete list of the 209 PCB congeners, see [[PCB congener list]]. Note that biphenyl, while not technically a PCB congener because of its lack of chlorine substituents, is still typically included in the literature.

{| class="wikitable"
|-
! PCB homolog
! CASRN
! Cl<br />substituents
! Number of<br />congeners
|-
| [[Biphenyl]] (not a PCB)
| 92-52-4
| 0
| 1
|-
| Monochlorobiphenyl
| 27323-18-8
| 1
| 3
|-
| Dichlorobiphenyl
| 25512-42-9
| 2
| 12
|-
| Trichlorobiphenyl
| 25323-68-6
| 3
| 24
|-
| Tetrachlorobiphenyl
| 26914-33-0
| 4
| 42
|-
| Pentachlorobiphenyl
| 25429-29-2
| 5
| 46
|-
| Hexachlorobiphenyl
| 26601-64-9
| 6
| 42
|-
| Heptachlorobiphenyl
| 28655-71-2
| 7
| 24
|-
| Octachlorobiphenyl
| 55722-26-4
| 8
| 12
|-
| Nonachlorobiphenyl
| 53742-07-7
| 9
| 3
|-
| Decachlorobiphenyl
| 2051-24-3
| 10
| 1
|-
|}

== See also ==
* [[Bay mud]]
* [[Organochlorine compound]]
* [[Polybrominated biphenyl]]
* ''[[Zodiac (novel)|Zodiac]]'', a novel by [[Neal Stephenson]] which involves PCBs and their impact on the environment.

== References ==
{{Reflist}}

== External links ==
{{Commons category|Polychlorinated biphenyls}}
* [http://www.atsdr.cdc.gov/toxprofiles/tp17.pdf ATSDR Toxicological Profile] U.S. Department of Health and Human Services
* [https://web.archive.org/web/20080306134819/http://monographs.iarc.fr/ENG/Monographs/suppl7/suppl7.pdf IARC PCB Monograph]
* [https://19january2017snapshot.epa.gov/pcbs_.html PCBs] – US EPA
* [https://ntpsearch.niehs.nih.gov/?query=PCB National Toxicology Program technical reports searched for "PCB"]
* [http://www.inchem.org/documents/cicads/cicads/cicad55.htm Polychlorinated Byphenyls: Human Health Aspects] by the [[WHO]]
* [https://www.cdc.gov/niosh/docs/78-127/78127_7.html Current Intelligence Bulletin 7: Polychlorinated (PCBs)]—NIOSH/CDC (1975)
* [https://www.canada.ca/en/health-canada/services/healthy-living/your-health/environment/pcbs.html It's Your Health – PCBs] ([[Health Canada]])

{{HealthIssuesOfPlastics|state=collapsed}}
{{Aryl hydrocarbon receptor modulators}}
{{Electric transformers}}

[[Category:Chloroarenes]]
[[Category:Flame retardants]]
[[Category:Endocrine disruptors]]
[[Category:IARC Group 2A carcinogens]]
[[Category:Soil contamination]]
[[Category:Synthetic materials]]
[[Category:Electric transformers]]
[[Category:Suspected testicular toxicants]]
[[Category:Suspected fetotoxicants]]
[[Category:Suspected female reproductive toxicants]]
[[Category:Persistent organic pollutants under the Convention on Long-Range Transboundary Air Pollution]]
[[Category:Persistent organic pollutants under the Stockholm Convention]]
[[Category:Monsanto]]
[[Category:Biphenyls]]