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 residential canal were compared with oysters from a reference site 1.2 km away. Canal oysters were frequently green in color and had 15 times more copper (≈ 200 μg/g wet wt.) and 2–3 times more arsenic (≈ 3 μg/g) than reference oysters. Histological examination of soft tissues showed significantly more metaplastic degeneration in digestive gland diverticula of canal oysters. Giemsa-stained canal oyster gill cells had twice as many micronuclei as did reference oyster gill cells. Reference oysters caged by the CCA-treated wood in the canal had Cu tissue accumulations approaching that of native canal oysters by three months. These did not show increased digestive gland 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. The 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 Stressors in the canal (e.g. boat exhaust, gardening chemicals) could also be involved.