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ZINC
Citation:
ZINC. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/1-78/034 (NTIS PB285130), 1978.
Description:
This report summarizes the available information on zinc as it relates to its effects on man and his environment. Zinc is found in most soils, but some areas are deficient in it. Metallurgic operations contribute to zinc contamination in air, water and soil. Trace amounts of zinc are essential for normal growth in plants, animals and humans, however, excessive levels can bring on zinc toxicosis. Zinc deficiency is known to have caused congenital malformations in pregnant rats. Severe liver disease is commonly associated with loss of total body zinc. Zinc is not a highly toxic substance. Zinc toxicosis may occur only when very high dose levels overwhelm the homeostatic mechanisms controlling zinc uptake and excretion. Reports suggest humans may ingest 500 mg to 1 g or more daily without adverse effects. Ten or more g taken as a single oral dose may produce gastrointestinal distress, including nausea, vomiting and diarrhea. There are also suggestions in the literature that even higher dosage may produce dizziness and perhaps increase blood levels of pancreatic enzymes. Inhalation of zinc has been related to metal fume fever, an acute disability of short duration that can occur when fume is inhaled from metal heated to a temperature above its melting point. With repeated exposure, some degree of tolerance may be built up, but it will be lost when exposure to fume ceases for a period as short as two days. The pathogenesis of this disorder, including the role of zinc in it, is not understood.