ABSTRACT
A large number of xenobiotics with endocrine-disrupting properties have been detected in marine mammal tissue (Wagemann and Muir, 1984; Aguilar and Borrell, 1995; Colborn and Smolen, 1996; Reijnders, 1996). Although most of the species known to be contaminated in this way are coastal, considerable concentrations of such compounds have even been detected in at least one cetacean that forages in deep water, the sperm whale (Physeter macrocephalus) (de Boer et al., 1998). Only in a few studies have observed reproductive disorders been found to be associated with certain chlorinated hydrocarbons and their metabolites. Among these studies are those involving ringed seals (Pusa hispida) and gray seals (Halichoerus grypus) in the Baltic Sea (Helle, 1980; Bergman and Olsson, 1985; see also Chapter 19 in this volume), beluga whales (Delphinapterus leucas) in the St. Lawrence River (Béland et al., 1987), harbor seals (Phoca vitulina) in the Wadden Sea (Reijnders, 1980), and California sea lions (Zalophus californianus) in the eastern Pacific Ocean (DeLong et al., 1973). The findings of these studies, although strongly suggestive, have not been conclusive. The etiology of the observed disorder has usually been uncertain, and proof of a causal relationship between exposure to a specific contaminant and an impact on the reproductive or endocrine system has remained elusive.
