Distinct Bioaccumulation and Partitioning of Polybrominated Diphenyl Ethers and Organochlorines in Northern Fur Seal Whiskers

Abstract

The eastern Pacific stock of northern fur seals (Callorhinus ursinus) on the Pribilof Islands, Alaska represents over 50% of the global breeding population, but it has experienced population declines of unknown cause(s) since 1980. One contributing factor to the decline may be exposure to anthropogenic contaminants such as persistent organic pollutants (POPs) which are biologically accumulative in nature, toxic to organisms, and environmentally persistent. This study conducted a decadal comparison of 21 organochlorine (OC) and 39 polybrominated diphenyl ether (PBDE) analyte concentrations utilizing archived vibrissae (whiskers) from individual fur seals sampled in 1993 (n=30) and 2013 (n=41) during subsistence harvests on the Pribilof Islands. The recently phased out PBDEs had values five times greater than the legacy status OCs. There were no significant mean concentration differences between 1993 and 2013 for total organochlorines (ΣOCs) (266 and 294 ng/g, respectively), or total polybrominated diphenyl ethers (ΣPBDEs) (1377 and 1521 ng/g, respectively), indicating the enduring environmental presence of these pollutants. Recently phased out PBDEs were detected at five times greater concentrations than phased out OCs, reflecting both the global shift away from chlorinated chemicals over the past 50 years and the widespread use of brominated flame retardants within the past two decades. The presence of all analytes in vibrissae indicate that there is an adaptive advantage to partitioning contaminants into this inert tissue, thereby validating keratinous tissue as a reliable long-term biomarker for POP exposure and introducing the potential for less invasive sampling for future monitoring efforts.

Keywords: Organochlorines, polybrominated diphenyl ethers, northern fur seal, Callorhinus ursinus, vibrissae, partitioning, SECLER