PATHOLOGICAL AND GENOTOXICOLOGICAL OBSERVATIONS IN OYSTERS (CRASSOSTREA-VIRGINICA) LIVING ON CHROMATED COPPER ARSENATE (CCA)-TREATED WOOD

Oysters living on chromated copper arsenate (CCA)-treated wood in a re sidential canal were compared with oysters from a reference site 1.2 k m away. Canal oysters were frequently green in color and had 15 times more copper (approximate to 200 mu g/g wet wt.) and 2-3 times more ars enic (approximate to 3 mu g/g) than reference oysters. Histological ex amination of soft tissues showed significantly more metaplastic degene ration in digestive gland diverticula of canal oysters. Giemsa-stained canal oyster gill cells had twice as many micronuclei as did referenc e oyster gill cells. Reference oysters caged by the CCA-treated wood i n the canal had Cu tissue accumulations approaching that of native can al oysters by three months. These did not show increased digestive gla nd metaplasia but did have a nearly doubled incidence of micronuclei. Cu has been shown to cause digestive gland pathology in bivalves; thus , the treated wood could be responsible for the observed pathology. Th e Cr and As from the wood although not accumulated to the extent of Cu , could influence the nonspecific response which was observed, Cr may also be responsible for the observed genotoxicity. Other possible stre ssors in the canal (e.g. boat exhaust, gardening chemicals) could also be involved.