Risk of high volume POP mixtures on the Arctic food chain

The exposure of the Arctic ecosystem to persistent organic pollutants(POPs) was assessed through a review of literature data . Concentrations of 21 chemicals or congeneric groups were estimated for seawater and for different levels of the Arctic food chain (zooplankton, polar cod, ringed seals, and polar bears). The ecotoxicologicalrisk, was estimated by applying the concentration addition (CA) concept. The risk of POP mixtures was absent in fish and very low in seals. By contrast, the risk was two orders of magnitude higher than the risk threshold for adult polar bears and even higher (three orders of magnitude above the threshold) for bear cubs fed with contaminated milk –. For some chemicals ( chlordanes, DDTs, dieldrin, HCB, HCHs, PBDE47, PCB153, PCDD, and PFOS) the database available for seals and bears allowed for calculation of a temporal trend from the 1960s . Starting in the 1980s, decreases in concentration for most legacy POPs, were evident, mainly due to international control measures. However, estimated half-lives indicated that concentrations of concern will persist at least up to the end of this century. Moreover, concentrations of the new POPs listed under the Stockholm Convention (e.g. PBDEs and PFOS) began to decrease only recently. These data support the urgent need for implementation of the Stockholm Convention for not yet controlled POPs.