Shinsuke Tanabe

Department of Environment Conservation, Ehime University
(3-5-7, Tarumi, Matsuyama 790-0905 Japan)

Abstract

The present paper overviews organochlorine contamination in marine mammals with regard to ecotoxicology. From a geographical point of view, organochlorine contamination is still spreading globally and tropical zones represent a major emission source for these toxic pollutants. In this context, oceans play an important role as the final depository for persistent organochlorines, and marine mammals tend to be making their homes amongst this garbage of toxic contaminants. Due to specific physiological functions, such as the presence of a large lipid pool (blubber) for accumulaton of organochlorines, lactational transfer of these contaminants in large quantities over generations and small capacity to degrade them, much greater amounts of toxic organochlorines are concentrated in the body of marine mammals through the food chain. Therefore, long-term accumulation and the chronic toxic effects are of great concern with regard to marine mammals, in particular the coplanar PCBs which evidenced the induction of P-450 enzyme systems were noticeable in seals and cetaceans. Additionally, it is unlikely that residue levels of toxic organochlorines in marine mammals will decline in the near future, suggesting that the adverse effects of these contaminants will steadily spread further to these animals.

Key words: persistent organochlorines, coplanar PCBs, marine mammals, global contamination, toxic effects