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INTRODUCTION
<br />Lead (Pb) has been known for centuries to be a cumulative metabolic
<br />poison; however, acute exposure is lessening. Of greater concern is the
<br />possibility that continuous exposure to low concentrations of the metal as a
<br />result of widespread environmental contamination may result in adverse health
<br />effects (Nriagu 1978b). Environmental pollution from Pb is now so high that
<br />body burdens in the general human population are closer than the burdens of
<br />any other toxic chemical to those that produce clinical poisoning (Hejtmancik
<br />et al. 1982). Further, Pb is a mutagen and teratogen when absorbed in
<br />excessive amounts, has carcinogenic or cocarcinogenic properties, impairs
<br />reproduction and liver and thyroid functions, and interferes with resistance
<br />to infectious diseases (EPA 1979).
<br />Ecological and toxicological aspects Tf lead and its compounds in the
<br />environment have been extensively reviewed. There is agreement by all
<br />authorities on five points. First, Pb is ubiquitous and is a characteristic
<br />trace constituent in rocks, soils, water, plants, animals, and air. Second,
<br />more than 4 million metric tons of Pb are produced worldwide each year, mostly
<br />for the manufacture of storage batteries, gasoline additives, pigments,
<br />alloys, and ammunition. The widespread broadcasting of Pb through
<br />anthropogenic activities, especially during the past 40 years, has resulted in
<br />an increase in Pb residues throughout the environment--an increase that has
<br />dislocated the equilibrium of the biogeochemical cycle of Pb. Third, Pb is
<br />neither essential nor beneficial to living organisms; all existing data show
<br />that its metabolic effects are adverse. Fourth, Pb is toxic in most of its
<br />chemical forms and can be incorporated into the body by inhalation, ingestion,
<br />dermal absorption, and placental transfer to the fetus. Fifth, Pb is an
<br />1Wetmore (1919), Bellrose (1959), Aronson (1971), Barth et al. (1973), NRCC
<br />(1973), Holl and Hampp (1975), Boggess (1977), Rolfe and Reinbold (1977),
<br />Forbes and Sanderson (1978), Nriagu (1978a, 1978b), Wong et al. (1978), CEP
<br />(1979), EPA (1979, 1980, 1985), Levander (1979), Tsuchiya (1979), Branica and
<br />Konrad (1980), Jenkins (1980), NAS (1980), Eisler (1981), Harrison and Laxen
<br />(1981), Demayo et al. (1982), Mudge (1983), De Michele (1984), Feierabend and
<br />Myers (1984), Walsh and Tilson (1984), Lumeij (1985), Feierabend and Russell
<br />(1986), FWS (1986a), Kania and Nash (1986), Lansdown and Yule (1986), McDonald
<br />(1986), Sanderson and Bellrose (1986), Pain (1987).
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