Why Is Lead an Environmental Problem

Of the heavy metals, lead, cadmium, tin and iron, the first two are toxic, the last two are not. We accept tin as a metal coating in contact with foodstuffs, and iron is even vital for human beings and mammals. The difference is due to the fact that lead and cadmium are markedly chalcophilic l (occur as sulfides in nature) while tin and iron are HthophiHc (occur mainly as oxides in nature). like all chalcophilic elements, lead has a strong tendency to bind sulfur. That is the reason for its toxicity. 

2) For more about chalcophilic and lithophilic elements, see Chapter 4 

This molecule forms a stable chelate complex with lead, which is excreted in the urine. 

Georgius Agricola, De Re MetaUica, Latin 43.3 edition 1556. Translation 1912 by H. C. 

Dover Publications, New York Marcus Vitruvius Pollio, de AwMlectutu lihri decern. Book VIII, chapter 6. Translated by Bin Thayer. Site updated 27 Jan 2002. http //www.ukans.edu/history/ 43.4 index/europe/ancienLrome/E/Roinan/ 

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