Abstract
There is increasing evidence that the ∼20 routinely monitored perfluoroalkyl and polyfluoroalkyl substances (PFASs) account for only a fraction of extractable organofluorine (EOF) occurring in the environment. To assess whether PFAS exposure is being underestimated in marine mammals from the Northern Hemisphere, we performed a fluorine mass balance on liver tissues from 11 different species using a combination of targeted PFAS analysis, EOF and total fluorine determination, and suspect screening. Samples were obtained from the east coast United States (US), west and east coast of Greenland, Iceland, and Sweden from 2000 to 2017. Of the 36 target PFASs, perfluorooctane sulfonate (PFOS) dominated in all but one Icelandic and three US samples, where the 7:3 fluorotelomer carboxylic acid (7:3 FTCA) was prevalent. This is the first report of 7:3 FTCA in polar bears (∼1000 ng/g, ww) and cetaceans (<6–190 ng/g, ww). In 18 out of 25 samples, EOF was not significantly greater than fluorine concentrations derived from sum target PFASs. For the remaining 7 samples (mostly from the US east coast), 30–75% of the EOF was unidentified. Suspect screening revealed an additional 37 PFASs (not included in the targeted analysis) bringing the total to 63 detected PFASs from 12 different classes. Overall, these results highlight the importance of a multiplatform approach for accurately characterizing PFAS exposure in marine mammals.
Highlights
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a diverse class of chemicals used throughout society.[1,2]
The bioaccumulation potential of PFASs is strongly correlated with perfluoroalkyl chain length; structures containing ≥8 fluorinated carbons for perfluoroalkyl carboxylic acids (PFCAs) and ≥6 fluorinated carbons for perfluoroalkyl sulfonic acids (PFSAs) are considered bioaccumulative.[6−8] perfluoroalkyl acids (PFAAs) are present in the blood of humans and wildlife globally, including remote polar regions.[9−11] Unlike classical persistent organic pollutants, PFASs accumulate primarily in protein-rich tissues such as liver and blood.[12]
Of the 36 target PFASs analyzed in the present work, 20 were quantifiable in one or more samples: PFHpA, perfluorooctanoic acid (PFOA) (L), concentrations were detected in harbor seals (640 ± 51 ng/g, ww) and ringed seals (536 ± 43 ng/g, ww) from Sweden
Summary
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a diverse class of chemicals used throughout society.[1,2] Perfluoroalkyl chains possess a wide range of unique properties, including extreme stability and combined oil/. A comparison of the measured concentration of PFOS using CIC to the amount fortified revealed an average recovery of 69 ± 2% (±standard deviation), which is reasonable considering that no internal standard is used for this procedure This value was used for recovery-correction of all EOF concentrations. Correction for analyte-specific recoveries would presumably give more accurate results, but this is impossible for unknown PFASs or PFASs lacking standards which contribute to the EOF Another option is to extract the samples without using ISs, split the final extract, and analyze this in both target and total fluorine analysis, adding IS to the fraction for targeted analysis only.[47] this approach leads to inaccuracies in the targeted data (because these data would be uncorrected for procedural losses), an additional extraction for targeted analysis with ISs could be included, assuming sufficient sample availability.
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