The highest levels of POPs are found in predatory and scavenger species such as the polar bear, arctic fox, great-black backed gull, glaucous gull, ivory gull and great skua. In these species the levels of pollutants have been associated with negative effects on the enzyme-, hormonal-, immune- and/or reproductive system. A reduced adult survival has also been related to the highest levels of PCBs and pesticides in the glaucous gull. Furthermore, some individuals of glaucous gulls on Svalbard have shown behavior similar to PCB-poisoned birds (in controlled laboratory trial) before their death. Analyses of the glaucous gulls from Svalbard revealed that brain and liver levels of pesticides and PCBs were extremely high. However, since these birds have used up all their fat resources before their death, and thereby increased the concentration of fat-soluble contaminants (PCBs and DDTs), a firm conclusion of a POP-related death could not be drawn. We believe, however, that the contaminants can accelerate an illness progress and indirectly cause death of these gulls.
PCBs make up the majority of POPs in all marine species. In birds and mammals, there are 5-50 times higher concentration of PCBs than hexachlorobenzene and 2-7 times more PCBs than DDTs. The levels of brominated flame retardants (PBDEs) constitute about 2-5 % of the total organic contaminants in seabirds. However, most of the “newer” contaminants, such as the perfluorinated compounds (PFCs), are not included in these numbers due to scarce and fragmented data.
The time trend series of seabird eggs from the Barents Sea area show that there has been a 70-80% reduction in the legacy pesticides and PCBs from 1983 to 2003. A strong increase of fluorinated (PFCs) and brominated (PBDEs) compounds were observed from 1983 to 1993, after which the concentrations leveled off. In general, the temporal trends of POPs in seabird eggs from the Barents Sea area mirror the production trends, and the global contaminant release. Overall, we observed reduction of compounds that is regulated, while compounds still in use increased in the seabird eggs.
Although current OC concentrations in seabird eggs from Northern Norway and Svalbard are lower than previously recorded, they still are much higher than the concentrations of BFRs and PFCs. The PCBs and DDTs accounts for the majority of the ‘total’ contaminant load. This illustrates that it takes a long time from the production of a contaminant is stopped until it is eliminated from the environment.
Several new POPs are showing up
Even though the concentration of most legacy contaminants in Arctic animals have been reduced since the production of these contaminants peaked between the 1970s and 1990s, several new threats exists. The human society continuously develops new chemicals as ‘old’ contaminants are put under restrictions. Many of these new chemicals have less adverse health effects than the old alternatives. They also have a lower bioaccumulative potential, a lower potential for long-range environmental transport and are not as persistent. Still, we are almost continuously discovering new chemicals in Arctic animals. The monitoring of both old and new chemicals must therefore continue in Arctic animals in order to give a ‘footprint’ of the global contaminant release.