Lead Poisoning in Birds

Abstract

Lead poisoning is still one of big problems in conservation of waterfowls. It is necessary to survey periodically lead contents in the organs of water fowls as it was considered to cause secondary poisoning in humans as well as wildlife management. We tried to assess risks of lead in wild and zoo birds for conservation and food safety for humans. Twenty-one swans rescued in Fukushima and Gifu Prefecture, 100 wild ducks captured in Gifu, and a penguin suspected of lead poisoning clinically in a zoo were necropsied to analyze lead content in the liver and kidneys. In swans, 21 of 13 had a higher level of lead content of more than 10,000 ng/g in the liver and kidney, of which the kidney showed a tendency to have more than 50,000 ng/g lead content. In ducks, 3 of 100 had a higher lead content of more than 500 ng/g, of which one had more than 10,000 ng/g lead content. A penguin had 49,800 and 8,530 ng/g in the liver and kidney, respectively. A metal blade in the stomach had 96.3% lead. Hisologically, the penguin had eosinophilic intranuclear inclusions in the epithelial cells of the urinary tubules, which were thought to be one of characteristics of lead poisoning. The swans frequently had lead shots in the gizzard, and a dark greenish colored liver and distended gall bladder with dense bile contents, and the most prominent histological finding was a marked deposition of brown hemosiderin pigment in the liver, spleen and kidney, with the liver showing varying degrees of necrosis. There were no marked alterations in the ducks with high lead contents. As there were occasional wild water fowls with higher content of lead, it is estimated that sporadic outbreaks of lead poisoning might be still occurring in some parts of Japan. It may be essential to monitor harmful metals including lead in waterfowls to prevent poisoning in wildlife as well as humans.