环境中铅和镉的来源及其对人和动物的危害

几十年来，由于科学技术的发展，环境中有毒或潜在有毒化学物，特别是重金属，种类和数量增加，对人和动物构成了严重威胁。在这些重金属中，铅和镉尤为突出，毒性最大。本文阐述了它们的主要来源，慢性毒性，长期容许量或安全标准，略述了这二种金属与其他元素或养分的相互作用，因为这些作用显著影响了它们的毒性，特别讨论了这些作用对二种金属的容许量或最小长期安全摄入量的影响及其复杂性，最后建议继续研究以找出显示铅和镉对人体亚临床反应的早期敏感性指标。

ENVIRONMENTAL SOURCES OF Pb AND Cd ANDTHEIR TOXICITY TO MAN AND ANIMALS

The principal sources, chronic toxic effects and long -term tolerances, or criteria ofsafety, of two of the most hazardons heavy metals-Pb and Cd -are described. Metabolicinteractions of these metals with other elements and nutrients, which significantly influencetheir toxicity to man and animals, are outlined. The effects of such interactions upon themaximum tolerances or minimum safe long-term intakes of these metals from the environ-ment are discussed and their complexity emphasized. Finally attention is drawn to the needfor increased research aimed at providing more sensitive early criteria of incipient or sub-clinical heavy metal toxicities in human.