Zinc toxicity is a medical condition involving an overdose on, or toxic overexposure to,

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

. Such toxicity levels have been seen to occur at ingestion of greater than 50 mg of zinc. 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. Zinc is an essential

trace metal Trace metals are the metals subset of trace elements; that is, metals normally present in small but measurable amounts in animal and plant cells and tissues and that are a necessary part of nutrition and physiology. Many biometals are trace me ...

with very low toxicity in humans.

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), nausea, vomiting, pain, cramps, and diarrhea may occur. There is evidence of induced

copper deficiency Copper deficiency, or hypocupremia, is defined either as insufficient copper to meet the needs of the body, or as a serum copper level below the normal range. Symptoms may include fatigue, decreased red blood cells, early greying of the hair, an ...

, alterations of blood lipoprotein levels, increased levels of LDL, and decreased levels of HDL at long-term intakes of 100 mg Zn/d. The USDA RDA is 15 mg Zn/d. 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 Zinc oxide is an inorganic compound with the formula . It is a white powder that is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, food supplements, rubbers, plastics, ceramics, glass, cement ...

formed during the

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as b ...

of galvanized materials.

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. A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake. Zinc has been popularly used as

zinc gluconate Zinc gluconate is the zinc salt of gluconic acid. It is an ionic compound consisting of two anions of gluconate for each zinc(II) cation. Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement providing 14.35% eleme ...

zinc acetate Zinc acetate is a salt with the formula Zn(CH3CO2)2, which commonly occurs as the dihydrate Zn(CH3CO2)2·2H2O. Both the hydrate and the anhydrous forms are colorless solids that are used as dietary supplements. When used as a food additive, it ha ...

lozenges for treating the common cold, and therefore the safety of usage at about 100 mg/day level is a relevant question. Thus, given that doses of over 150 mg/day for months to years has caused no permanent harm in many cases, a one-week usage of about 100 mg/day of zinc in the form of lozenges would not be expected to cause serious or irreversible adverse health issues in most individuals. Unlike

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

, the elimination of zinc is concentration-dependent.

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.

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.

References

External links

{{DEFAULTSORT:Zinc Toxicity Toxic effects of metals