ABSTRACT
The 1988 phocine distemper virus (PDV) epizootic which killed 20 000 harbour seals (Phoca vitulina) and several hundred grey seals (Halichoerus grypus) in northern Europe catapulted the issue of immunotoxicity into the public domain (Dietz et al., 1989a). The toxic effects of low levels of many persistent organic pollutants (POPs) on the immune system have been clearly demonstrated in laboratory animals (Vos and Luster, 1989), and many immunotoxic contaminants were present at high levels in the blubber of pinnipeds inhabiting the areas affected by the virus (Hall et al., 1992a; Hutchinson and Simmonds, 1994; Olsson, 1994). An additional mortality of 10 000 Baikal seals (Pusa sibirica) in 1987-88 was attributed to canine distemper virus, or CDV (Grachev et al., 1989; Visser et al., 1990), which, along with PDV, is a member of the genus Morbillivirus (Osterhaus et al., 1995). Baikal seals have since been shown to be highly contaminated with POPs (Nakata et al., 1997).
