| 1. |
- Benskin, Jonathan P., et al.
(författare)
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Perfluoroalkyl Acids in the Atlantic and Canadian Arctic Oceans
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society. - 0013-936X .- 1520-5851. ; 46:11, s. 5815-5823
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Tidskriftsartikel (refereegranskat)abstract
- We report here on the spatial distribution of C-4, C-6, and C-8 perfluoroalkyl sulfonates, C-6-C-14 perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (Sigma PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). Sigma PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L Sigma PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, Sigma PFAAs were less than210 pg/L. PFOA/PFOS ratios were typically greater than= 1 in the northern hemisphere, similar to 1 near the equator, and less than= 1 in the southern hemisphere. In the Canadian Arctic, Sigma PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically greater thangreater than1) decreased from Baffin Bay to the Amundsen Gulf; possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.
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| 2. |
- Chibwe, Leah, et al.
(författare)
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C12-30 alpha-Bromo-Chloro Alkenes : Characterization of a Poorly Identified Flame Retardant and Potential Environmental Implications
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:18, s. 10835-10844
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Tidskriftsartikel (refereegranskat)abstract
- Bromo-chloro alkenes (Br-Cl PXAs) have been used for over 30 years as flame retardants and are listed on several national chemical inventories. Very little publicly available information is available on Br-Cl PXAs, and thus preliminary ecological risk screening is challenging due to the lack of basic information such as molecular structure and associated physicochemical properties. Due to their likely similarity with chlorinated paraffins (CPs), Br-Cl PXAs may pose a similar environmental hazard. Several structural databases list such substances as alkenes, although the industrial synthesis involves halogenation of linear alpha-olefins and would be expected to produce linear alkanes. In this study, a combination of high-resolution separation and mass spectrometric techniques were used to characterize a Br-Cl PXA industrial technical product, C12-30 bromo-chloro alpha-alkenes (CAS RN 68527-01-5). The results show this product is dominated by C-18 carbon chain lengths, substituted with 3-7 chlorine atoms and 1-3 bromine atoms on an alkane chain. Long-chain C-18 chlorinated paraffins are also present, although they represent a relatively minor component. Experimental log K-OW (6.9 to 8.6) and estimated log K-OA (10.5 to 13.5) and log K-AW (-5.1 to -0.6) partition coefficients suggest that this chemical will behave similarly to medium- and long-chain CPs as well as other persistent organic pollutants, such as highly chlorinated pesticides and polychlorinated biphenyls. The results of this study provide an initial step toward understanding the environmental behavior and persistence of Br-Cl PXAs, highlighting the need for further assessment and re-evaluation of the current structure(s) assigned to these compounds.
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| 3. |
- De Silva, Amila O., et al.
(författare)
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PFAS Exposure Pathways for Humans and Wildlife : A Synthesis of Current Knowledge and Key Gaps in Understanding
- 2021
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Ingår i: Environmental Toxicology and Chemistry. - : Pergamon Press. - 0730-7268 .- 1552-8618. ; 40:3, s. 631-657
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Forskningsöversikt (refereegranskat)abstract
- Here we synthesize current understanding of the magnitudes and methods for assessing human and wildlife exposures to poly- and perfluoroalkyl substances (PFAS). Most human exposure assessments have focused on two to five legacy PFAS and wildlife assessments are typically limited to targeted PFAS (up to ~30 substances). However, shifts in chemical production are occurring rapidly and targeted methods for detecting PFAS have not kept pace with these changes. Total fluorine (TF) measurements complemented by suspect screening using high resolution mass spectrometry are thus emerging as essential tools for PFAS exposure assessment. Such methods enable researchers to better understand contributions from precursor compounds that degrade into terminal perfluoroalkyl acids (PFAA). Available data suggest that diet is the major human exposure pathway for some PFAS but there is large variability across populations and PFAS compounds. Additional data on TF in exposure media and the fraction of unidentified organofluorine are needed. Drinking water has been established as the major exposure source in contaminated communities. As water supplies are remediated, and for the general population, exposures from dust, personal care products, indoor environments and other sources may be more important. A major challenge for exposure assessments is the lack of statistically representative population surveys. For wildlife, bioaccumulation processes differ substantially between PFAS and neutral lipophilic organic compounds, prompting a revaluation of traditional bioaccumulation metrics. There is evidence that both phospholipids and proteins are important for the tissue partitioning and accumulation of PFAS. New mechanistic models for PFAS bioaccumulation are being developed that will assist in wildlife risk evaluations.
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| 4. |
- Yeung, Leo W. Y., 1981-, et al.
(författare)
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Perfluoroalkyl substances and extractable organic fluorine in surface sediments and cores from Lake Ontario
- 2013
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 59, s. 389-397
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Tidskriftsartikel (refereegranskat)abstract
- Fourteen perfluoroalkyl substances (PFASs) including short-chain perfluorocarboxylates (PFCAs, C4-C6) and perfluoroalkane sulfonates (PFSAs, C4 and C6) were measured in surface sediment samples from 26 stations collected in 2008 and sediment core samples from three stations (Niagara, Mississauga, and Rochester basins) collected in 2006 in Lake Ontario. Perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUnDA) were detected in all 26 surface sediment samples, whereas perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonamide (FOSA), perfluorododecanoate (PFDoDA) and perfluorobutanoate (PFBA) were detected in over 70% of the surface sediment samples. PFOS was detected in all of the sediment core samples (range: 0.492-30.1ngg-1 d.w.) over the period 1952-2005. The C8 to C11 PFCAs, FOSA, and PFBA increased in early 1970s. An overall increasing trend in sediment PFAS concentrations/fluxes from older to more recently deposited sediments was evident in the three sediment cores. The known PFCAs and PFSAs accounted for 2-44% of the anionic fraction of the extractable organic fluorine in surface sediment, suggesting that a large proportion of fluorine in this fraction remained unknown. Sediment core samples collected from Niagara basin showed an increase in unidentified organic fluorine in recent years (1995-2006). These results suggest that the use and manufacture of fluorinated organic compounds other than known PFCAs and PFSAs has diversified and increased.
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