Induction of micronuclei in vitro by organochlorine compounds in beluga whale skin fibroblasts

Beluga whales (Delphinapterus leucas) inhabiting the St. Lawrence estuary a re highly contaminated with environmental pollutants and have a high incide nce of cancer. Environmental contaminants may be partly responsible for the high cancer incidence observed in this population. DNA damage plays an imp ortant role in the development of cancer. The micronuclei (MN) assay was us ed to test the genotoxic potential of organochlorine (OC) pesticides with a nd without external metabolic factor in skin fibroblasts of an Arctic belug a whale. Toxaphene, chlordane and p,p'-DDT induced significant (p < 0.05) c oncentration-response increases of micronucleated cells (MNCs). Statistical ly significant increases in MNCs, ranging from 1.7- to 5-folds when compare d to control cultures, were observed for 0.05, 0.5, 5 and 10 mu g/ml toxaph ene, 2, 5 and 10 mu g/ml chlordane and 10 and 15 mu g/ml p,p'-DDT. Presence of exogeneous metabolic factor (S9) completely abolished the MN induction potency of chlordane and p,p'-DDT, and toxaphene induced MN formation at hi gher concentrations (0.5 mu g/ml) than without S9 mix. The ecotoxicological significance of MN induction by low concentrations of toxaphene is unknown and do not imply that toxaphene is involved in the etiology of cancer in S t. Lawrence beluga whales. However, because of the known genotoxicity of to xaphene and the long lifespan of beluga whales, it cannot be excluded that toxaphene may pose a long-term genetic hazard to the more contaminated whal es of this population. (C) 1999 Elsevier Science B.V. All rights reserved.