Tohoku J. Exp. Med., 2001, 194 (4)

Special Article

Reappraisal of the Historic 1959 Cat Experimentin Minamata by the Chisso Factory

KOMYO ETO, AKIRA YASUTAKE, ATSUHIRO NAKANO, HIROKATSU AKAGI,
HIDEHIRO TOKUNAGA¹ and TERUYOSHI KOJIMA²

National Institute for Minamata Disease, Minamata 867-0008,
¹Department of Surgical Pathology, Kumamoto University School of Medicine, Kumamoto 860-8556, and
²Teramoto General Welfare Center, Osaka 586-0094

Autopsy specimens from the historic cat experiment were recently discovered in a storage area at the Kumamoto University School of Medicine. The specimens were from an experiment prompted by physicians in the Chisso Minamata Plant following the announcement made by the Study Group for Minamata disease. On July 14, 1959 the Group announced that the disease was most likely caused by a kind of organic mercury. In order to prove or disprove that industrial waste from the Chisso Factory was the culprit in Minamata disease, a total of ten cats were fed food mixed with industrial waste produced in the acetaldehyde-producing plant. One of the ten cats, No. 717, was subsequently autopsied but the autopsy findings have never been published or recorded in the literature despite their historic significance. The rediscovered specimens were studied pathologically and biochemically, and were analyzed chemically with currently available techniques. Characteristic lesions of methylmercury poisoning were observed in the central nervous system, and the mercury levels in the cerebrum, cerebellum, liver and kidney were found to be markedly elevated in this animal.

Keywords —— methylmercury poisoning; pathology; cats; Chisso Factory

© 2001 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2001, 194, 197-203

Address for reprints: Komyo Eto, Director of Department of Clinical Medicine, National Institute for Minamata Disease, Ministry of the Environment, 4058-18 Hama, Minamata 867-0008, Japan.

e-mail: kometo@nimd.go.jp