Hexabromocyclododecanes (HBCDs) in the environment and humans: A review

Hexabromocyclododecanes (HBCDs) are brominated aliphatic cyclic hydrocarbons used as flame retardants in thermal insulation building materials, upholstery textiles, and electronics. As a result of their widespread use and their physical and chemical properties, HBCDs are now ubiquitous contaminants in the environment and humans. This review summarizes HBCD concentrations in several environmental compartments and analyzes these data in terms of point sources versus diffuse sources, biomagnification potential, stereoisomer profiles, time trends, and global distribution. Generally, higher concentrations were measured in samples (air, sediment, and fish) collected near point sources (plants producing or processing HBCDs), while lower concentrations were recorded in samples from locations with no obvious sources of HBCDs. High concentrations were measured in top predators, such as marine mammals and birds of prey (up to 9600 and 19 200 ng/g lipid weight, respectively), suggesting a biomagnification potential for HBCDs. Relatively low HBCD concentrations were reported in the few human studies conducted to date (median values varied between 0.35 and 1.1 ng/g lipid weight). HBCD levels in biota are increasing slowly and seem to reflect the local market demand. One important observation is the shift from the high percentage of the gamma-HBCD stereoisomer in the technical products to a dominance of the alpha-HBCD stereoisomer in biological samples. A combination of factors such as variations in solubility, partitioning behavior, uptake, and, possibly, selective metabolism of individual isomers may explain the observed changes in stereoisomer patterns. Recommendations for further work include research on how HBCDs are transferred from products into the environment upon production, use, and disposal. Time trends need to be analyzed more in detail, including HBCD stereoisomers, and more data on terrestrial organisms are needed, especially for humans. Whenever possible, HBCDs should be analyzed as individual stereoisomers in order to address their fate and effects

Temporal Trends of Brominated and Fluorinated Contaminants in Canadian Arctic Beluga Delphinapterus leucas

Limited information exists regarding contemporary and historical emissions for many anthropogenic chemicals, especially for contaminants of emerging concern (CECs). This study examined temporal trends of several perfluoroalkyl substances (PFASs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecanes (HBCDs) in three beluga whale populations from the Canadian Arctic (Hendrickson Island (HI), NT; Pangnirtung (PG), NU; and Sanikiluaq (SQ), NU) collected from 1982-2013. The confounding factors of animal size, age, and sex were included in the analyses, but were only significant for some CECs. The strongest temporal resolution was obtained from HI, which showed increasing trends in PBDEs (4.8%/yr) and HBCDs (2.9%/yr), and decreases in perfluoroalkylcarboxylic acids (PFCAs, -6.0%/yr). Concentrations of perfluorooctanesulfonate (PFOS) were relatively stable between 1984-2010, increasing substantially in 2011; trends in perfluorooctanesulfonamide (PFOSA) concentrations were not strictly linear over the study period. PBDE, HBCD, and PFCA trends in the HI population were opposite/different to that of many other arctic animals (e.g. polar bears) for the same time-period. Trends were inconsistent among locations, suggesting that regional differences in dietary exposure and/or sources may also impact these trends. The effects of climate change-driven processes on the exposure and distribution of CECs are currently not well understood, highlighting a need for ongoing contaminant monitoring.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Fluorinated organic compounds in an Eastern arctic marine food web

An eastern Arctic marine food web was analyzed for perfluorooctanesulfonate (PFOS, C8F17SO3-), perfluorooctanoate (PFOA, C7F15COO-), perfluorooctane sulfonamide (PFOSA, C8F17SO2NH2), and N-ethylperfluorooctane sulfonamide (N-EtPFOSA, C8F 17SO2NHCH2CH3) to examine the extent of bioaccumulation. PFOS was detected in all species analyzed, and mean concentrations ranged from 0.28 ± 0.09 ng/g (arithmetic mean ± 1 standard error, wet wt, whole body) in clams (Mya truncate) to 20.2 ± 3.9 ng/g (wet wt, liver) in glaucous gulls (Larus hyperboreus). PFOA was detected in approximately 40% of the samples analyzed at concentrations generally smaller than those found for PFOS; the greatest concentrations were observed in zooplankton (2.6 ± 0.3 ng/g, wet wt). N-EtPFOSA was detected in all species except redfish with mean concentrations ranging from 0.39 ± 0.07 ng/g (wet wt) in mixed zooplankton to 92.8 ± 41.9 ng/g (wet wt) in Arctic cod (Boreogadus saida). This is the first report of N-EtPFOSA in Arctic biota. PFOSA was only detected in livers of beluga (Delphinapterus leucas) (20.9 ± 7.9 ng/g, wet wt) and narwhal (Monodon monoceros) (6.2 ± 2.3 ng/g, wet wt), suggesting that N-EtPFOSA and other PFOSA-type precursors are likely present but are being biotransformed to PFOSA. A positive linear relationship was found between PFOS concentrations (wet wt) and trophic level (TL), based on §15N values, (r2 = 0.51, p \u3c 0.0001) resulting in a trophic magnification factor of 3.1. TL-corrected biomagnification factor estimates for PFOS ranged from 0.4 to 9. Both results indicate that PFOS biomagnifies in the Arctic marine food web when liver concentrations of PFOS are used for seabirds and marine mammals. However, transformation of N-EtPFOSA and PFOSA and potential other perfluorinated compounds to PFOS may contribute to PFOS levels in marine mammals and may inflate estimated biomagnification values. None of the other fluorinated compounds (N-EtPFOSA, PFOSA, and PFOA) were found to have a significant relationship with TL, but BMFTL values of these compounds were often \u3e1, suggesting potential for these compounds to biomagnify. The presence of perfluorinated compounds in seabirds and mammals provides evidence that trophic transfer is an important exposure route of these chemicals to Arctic biota