Zinc toxicity
Script error: No such module "about". Template:Infobox medical condition (new) Zinc toxicity is a medical condition involving an overdose on, or toxic overexposure to, zinc. Such toxicity levels have been seen to occur at ingestion of greater than 50 mg of zinc.[1]Template:Unreliable medical source Excessive absorption of zinc can suppress copper and iron absorption. The free zinc ion in solution is highly toxic to bacteria, plants, invertebrates, and even vertebrate fish.[2][3][4] Zinc is an essential trace metal with very low toxicity in humans.[1][5]
Signs and symptoms
Following an oral intake of extremely high doses of zinc (where 300 mg Zn/d – 20 times the US RDA – is a "low intake" overdose[1]), nausea, vomiting, pain, cramps, and diarrhea may occur.[1] There is evidence of induced copper deficiency, alterations of blood lipoprotein levels, increased levels of LDL, and decreased levels of HDL at long-term intakes of 100 mg Zn/d.[1] The USDA RDA is 15 mg Zn/d.[1] There is also a condition called the "zinc shakes", "zinc chills", or metal fume fever that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials.[6]
High levels of intake by humans
Zinc has been used therapeutically at a dose of 150 mg/day for months, or in some cases for years, and in one case at a dose of up to 2000 mg/day zinc for months.[7][8][9][10][11] A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake.[9]
Zinc has been popularly used as zinc gluconate or zinc acetate lozenges for treating the common cold,[12] and therefore the safety of usage at about 100 mg/day level is a relevant question.
Unlike iron, the elimination of zinc is concentration-dependent.[13]
Cross-reaction toxicity
Supplemental zinc can prevent iron absorption, leading to iron deficiency. Zinc and iron should be taken at different times of the day.[14]
Diagnosis
Zinc concentrations are typically quantified using instrumental methods such as atomic absorption, emission, or mass spectroscopies; X-ray fluorescence; electro-analytical techniques (e.g., stripping voltammetry); or neutron activation analysis. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is used for zinc determinations in blood and tissue samples (NIOSH Method 8005) and in urine (NIOSH Method 8310). Detection limits in blood and tissue are 1 μg/100 g and 0.2 μg/g, respectively, with recoveries of 100% (NIOSH 1994). Sample preparation involves acid digestion using concentrated acids. Detection of zinc in urine samples requires extraction of the metals with a polydithiocarbamate resin prior to digestion and analysis (NIOSH 1984). Detection limits in urine are 0.1 μg/sample.
Treatment
Treatment of zinc toxicity consists of eliminating exposure to zinc. However, no antidotes are available.Script error: No such module "Unsubst".
See also
References
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External links
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