ABSTRACT
The toxicities of heavy metal ions are well known.1 These include cadmium, chromium, cobalt, copper, lead, mercury, tin, and zinc. For convenience, nonmetals such as arsenic, asbestos, and selenium are also included here. Mercury-containing wastes dumped into Minamata Bay in Japan killed hundreds of people and sickened many more.2 Hundreds of deaths also occurred in Iraq when people ate grain treated with an organomercury biocide intended to protect the young seedlings from fungi.3 The expression “mad as a hatter” originated when hatters got poisoned with the mercury compounds used in the felting of hats. Some authors have postulated the poisoning of modern man from silver amalgam dental llings, much as lead poisoning from the use of lead cooking and storage vessels may have led to the decline of the Roman empire.4 Dentists are being encouraged to separate the mercury from waste amalgam before it goes down the drain.5 In 1995, shermen in the United States were advised not to eat the sh that they caught in 1306 different bodies of water because of the mercury in them.6 This gure should be compared with 438 advisories for polychlorinated biphenyls, 122 for chlordane, 52 for dioxins, and 35 for DDT. Game sh may accumulate mercury to 225,000 times the concentration in the surrounding water.7 There is enough mercury in the Florida Everglades to poison some wading birds that feed on sh.8 The amount of mercury that people should be allowed to eat in sh is a matter of current debate.9
