Trace Elements

More than 60 elements have been found in micro-organisms, higher plants and animals, including man. Those ordinarily present in tissues only in minute quantity, picograms to micrograms per gram of wet organ, are arbitrarily designated "trace elements"; about a dozen are now considered essential for animal life (Table 1).Deprivation of essential trace elements produces discrete deficiency states characterized in many species by impaired growth, reproductive failure and shortened life-span. Excessive accumulation of metals, arising either through failure of intrinsic control mechanisms or through unusual environmental exposure, produces toxicity. Whether the available quantity of an essential element is inadequate or . . .