Levels and trends of poly-and perfluoroalkyl substances in the Arctic environment-An update

Poly-and perfluoroalkyl substances(PFASs)are important environmental contaminants globally and in the early 2000s they were shown to be ubiquitous contaminants in Arctic wildlife.Previous reviews by Butt et al.and Letcher et al.have covered studies on levels and trends of PFASs in the Arctic that were available to 2009.The purpose of this review is to focus on more recent work,generally published between 2009 and 2018,with emphasis on PFASs of emerging concern such as perfluoroalkyl carboxylates(PFCAs)and short-chain perfluoroalkyl sulfonates(PFSAs)and their precursors.Atmospheric measurements over the period 2006e2014 have shown that fluorotelomer alcohols(FTOHs)as well as perfluorobutanoic acid(PFBA)and perfluoroctanoic acid(PFOA)are the most prominent PFASs in the arctic atmosphere,all with increasing concentrations at Alert although PFOA concentrations declined at the Zeppelin Station(Svalbard).Results from ice cores show generally increasing deposition of PFCAs on the Devon Ice cap in the Canadian arctic while declining fluxes were found in a glacier on Svalbard.An extensive dataset exists for long-term trends of long-chain PFCAs that have been reported in Arctic biota with some datasets including archived samples from the 1970s and 1980s.Trends in PFCAs over time vary among the same species across the North American Arctic,East and West Greenland,and Svalbard.Most long term time series show a decline from higher concentrations in the early 2000s.However there have been recent(post 2010)increasing trends of PFCAs in ringed seals in the Canadian Arctic,East Greenland polar bears and in arctic foxes in Svalbard.Annual biological sampling is helping to determine these relatively short term changes.Rising levels of some PFCAs have been explained by continued emissions of long-chain PFCAs and/or their precursors and inflows to the Arctic Ocean,especially from the North Atlantic.While the effectiveness of biological sampling for temporal trends in long-chain PFCAs and PFSAs has been demonstrated,this does not apply to the C4eC8ePFCAs,perfluorobutane sulfonamide(FBSA),or perfluorobutane sulfonate(PFBS)which are generally present at low concentrations in biota.In addition to air sampling,sampling abiotic media such as glacial cores,and annual sampling of lake waters and seawater would appear to be the best approaches for investigating trends in the less bioaccumulative PFASs.

Identifying further chemicals of emerging arctic concern based on‘in silico’screening of chemical inventories

In the past 12 years several studies have screened lists of thousands of chemicals available in the industrial chemical inventories of the European Union,the USA and Canada with the goal of identifying and prioritizing chemicals which are persistent(P),bioaccumulative(B)and toxic(T).Most studies have selected chemicals based on whether their predicted P and B properties and their long-range transport potential exceed guideline thresholds for evaluation of persistent organic pollutants(POPs).A major goal of this study was to review this recent literature on computer-based or‘in silico’screening for POPs.A second goal was to review other approaches for finding previously unidentified chemicals of concern including targeted and non-target analytical approaches that might use lists of suspect chemicals developed from‘in silico’screening studies.Eight studies were reviewed along with several others which examined the screening process and its uncertainties.From these studies we assembled a list of 3421 chemicals,after removing duplicates and substances already on the Stockholm Convention on POPs.About 52%of these were halogenated,while 48%consisted of a broad range of non-halogenated organics.This list was then further analysed by calculating an overall“POPs score”for transport and accumulation in the Arctic for each substance using predicted partition coefficients,overall persistence,transfer efficiency,and bioaccumulation factor.A shorter list of twenty-five substances was developed based on their POPs score ranking.These substances had not been previously analysed in environmental media but were nevertheless on current or recent chemical inventories indicating significant commercial use.