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effective antidote to counteract the effects of methylmercury on the central
<br />nervous system (Elhassani 1983).
<br />Poisoning of game birds and other wildlife in Sweden, apparently by seeds
<br />treated with organomercurials, was noticed in 1960 (Das et al. 1982). Massive
<br />kills of the grey heron (Ardea cinerea) in the Netherlands during 1976, were
<br />attributed to a combination of low temperatures, undernourishment, and high
<br />body burdens of mercury (Van der Molen et al. 1982). Mercury contamination
<br />has resulted in the closure of pheasant and partridge hunting areas in
<br />Alberta, Canada (Mullins et al. 1977). In 1967, the Swedish medical board
<br />banned the sale of fish that contained high concentrations of organomercury
<br />salts, originating from about 40 lakes and rivers (Das et al. 1982). In 1970,
<br />after the discovery of high levels of mercury in fish from Lake St. Clair,
<br />Canada, restrictions on fishing and the sale of fish were imposed in many
<br />areas of the United States and Canada (Das et al. 1982). Since 1970, a total
<br />of 26 of the 48 States in the conterminous United States have reported mercury
<br />pollution in their waters as a direct result of human activities. These States
<br />have banned sport or commercial fishing in Hg-contaminated waters, or have
<br />issued health warnings about the consequences of eating Hg-contaminated fish
<br />or seafood from selected water courses, or have placed restrictions on fish
<br />consumption from certain streams, lakes, or rivers polluted with mercury (NAS
<br />1978). In general, the number of Hg-contaminated fish and wildlife habitats
<br />has progressively increased--almost all as a direct result of anthropogenic
<br />activities (Boudou and Ribeyre 1983).
<br />Most authorities on Hg ecotoxicology agree on six points. First, Hg and
<br />its compounds have no known biological function, and its presence in living
<br />organisms is undesirable and potentially hazardous. Second, forms of mercury
<br />with relatively low toxicity can be transformed into forms with very high
<br />toxicity through biological and other processes. Third, methylmercury can be
<br />bioconcentrated in organisms and biomagnified through food chains, returning
<br />mercury directly to man and other upper trophic level consumers in
<br />concentrated form. Fourth, mercury is a mutagen, teratogen, and carcinogen,
<br />and causes embryocidal, cytochemical, and histopathological effects. Fifth,
<br />high body burdens of mercury normally encountered in some species of fish and
<br />wildlife from remote locations emphasize the complexity of natural mercury
<br />cycles and human impacts on these cycles. And finally, the anthropogenic use
<br />of mercury should be curtailed, because the difference between tolerable
<br />natural background levels of mercury and harmful effects in the environment is
<br />exceptionally small. These, and other aspects of mercury and its compounds in
<br />the environment as a result of anthropogenic or natural processes, have been
<br />the subject of many reviews, including those by Montague and Montague (1971),
<br />D'Itri (1972), Friberg and Vostal (1972), Jernelov et al. (1972, 1975), Keckes
<br />and Miettinen (1972), Buhler (1973), Holden (1973), D'Itri and D'Itri (1977),
<br />Eisler (1978, 1981), NAS (1978), Birge et al. (1979),.Magos and Webb (1979),
<br />Nriagu (1979), EPA (1980, 1985), Jenkins (1980), Clarkson and Marsh (1982),
<br />Das et al. (1982), Boudou and Ribeyre (1983), Elhassani (1983), Clarkson et
<br />al. (1984), Robinson and Touvinen (1984), and Wren (1986).
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