title: Contaminant-induced immunosuppression and mass mortalities among harbor seals.
abstract: Virus-associated mass mortalities among seals inhabiting northwestern Europe have generated an interest in immunotoxicology in this species. A morbillivirus has been isolated from victims, but a contribution of immunotoxic contaminants to the severity of the outbreaks could not be ruled out. Fish-eating seals occupy high trophic levels in the aquatic food chain, and accumulate high levels of contaminants including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). Such chemicals have been found to be immunotoxic at low doses in studies of laboratory animals. We carried out an immunotoxicological study, in which captive harbor seals (Phoca vitulina) were fed herring from either relatively uncontaminated sites of the Atlantic Ocean, or from the highly contaminated Baltic Sea. In this report we summarize the contaminant-related immunosuppression observed in the captive group of seals fed herring from the Baltic Sea. In addition, we describe two parallel studies, in which laboratory rats are exposed as adults or perinatally to the contaminants in the Baltic Sea herring, exhibiting immunotoxicity. On the basis of these studies we conclude that complex mixtures of environmental contaminants including PCBs, PCDFs, and PCDDs may represent a real immunotoxic risk to free-ranging seals.
authors.affiliation: Laboratory for Pathology, National Institute of Public Health and the Environment, 3720 BA, Bilthoven, The Netherlands. h.van.loveren@rivm.nl
authors.forename: H
authors.initials: H
authors.lastname: Van Loveren
authors.forename: P S
authors.initials: PS
authors.lastname: Ross
authors.forename: A D
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: J G
authors.initials: JG
authors.lastname: Vos
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D004032:Diet; D004196:Disease Outbreaks / Q000662:veterinary*; D020387:Food Chain; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D007107:Immune System / Q000187:drug effects; D007108:Immune Tolerance / Q000187:drug effects*; D018185:Morbillivirus Infections / Q000401:mortality / Q000662:veterinary*; D010573:Pesticide Residues / Q000633:toxicity*; D011078:Polychlorinated Biphenyls / Q000633:toxicity; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives / Q000633:toxicity; D051381:Rats; D046048:Seals, Earless; D012989:Soil Pollutants / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006843:Hydrocarbons, Chlorinated; D010573:Pesticide Residues; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls