1) The effects of copper on oyster were studied, in vitro, since there are many water pollution troubles on the wastes included copper compound in Japan, recently.
2) The TLm value for 96 hrs. of copper to oyster was estimated 1.9 ppm, and there is no lethal effects on oyster actually, except the places near-by outfalls.
3) A dissociation and regressive change of digestive diverticula and desquamation and necrosis of the stomach epithelia were observed, histo-pathologically. On the other hand, the decrease of RNA was observed, cyto-chemically. Then, it was assumed that a poor growth of the organism would be made by the waste.
4) It was estimated that the oyster cultured in sea water mixed small quantity of copper deposited much copper in the bodies, and became unfit for a food material.