New mechanisms in lead biodynamics at ultra-low levels.
It has been found that the mean concentration of 15 micrograms Pb/g bone ash in typical Americans today is 1000 times greater than the natural level of lead in Homo sapiens sapiens determined from analyses of ancient human bones. Since body burdens of lead only 3 to 5-fold greater than typical induce overtly poisonous effects, unrecognized dysfunctions caused by lead are probably widespread among Americans. Previous toxicological studies by others to delineate ill effects were made by comparisons of biological systems to which lead was added with systems to which no lead was added. It is now seen that such studies dealt entirely with unnatural mechanisms in lead biodynamics, and provided no knowledge of the operation of unperturbed natural mechanisms, because "non-leaded" controls were actually highly traumatized by unrecognized excessive lead exposures. New work should be carried out that would use an ultra-low lead diet to grow rats possessing "natural" lead levels which could be used as controls. Metabolisms of lead in these controls should be compared with metabolisms of lead in biological systems of rats traumatized by excessive lead exposures corresponding to typical levels within people today. Such comparisons would disclose previously unknown characteristics of intra-cellular processing of lead within osseous, neuronal, hepatic, renal and muscle tissues, and in red blood cells and sera, together with sizes and residence times of lead reservoirs in those tissues during fetal growth, maturation and adult aging in rats exposed to natural lead levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Patterson
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Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125.
Settle
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D000818:Animals; D001822:Body Burden; D004785:Environmental Pollutants / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D006801:Humans; D007854:Lead / Q000378:metabolism / Q000494:pharmacology*; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D051381:Rats
D004785:Environmental Pollutants; D007854:Lead