Perfluoroalkyl acids (PFAAs) have been widely used in commercial and industrial products for several decades. To alleviate the exposure risk to perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), industrial and government actions have been taken to reduce the production and applications of PFAAs. However, the concentrations of PFOA and PFOS in the environment did not decrease as predicted. Apart from direct release, indirect sources could make a certain contribution to PFAAs due to degradation of some PFAA precursor materials. Isomeric analysis could give some clues for identifying the sources of PFAAs in the environment. Isomeric degradation of perfluorooctane sulfonamide (PFOSA) was concomitantly investigated by in vivo and in vitro tests using common carp as an animal model. The results indicated Br-PFOSA isomers were preferentially metabolized to Br-PFOS than n-PFOSA. This may explain the observed enriched Br-PFOS in the surface water (58.4%) in Taihu Lake. Human exposure to PFAAs via different pathways were investigated. For PFOS, the predicted n-PFOS (69.3%) was much higher than the previously observed values (59.2%) in human serum, which also suggested there was a contribution from indirect sources. However, such significant enrichment in branched isomers in water or biota was not observed for perfluorohexane sulfonate (PFHxS), implying that indirect source for PFHxS was not significant. Bark samples, which served as passive airborne PFAAs, were collected around a Chinese fluorochemical manufacturing park (FMP) and analyzed for PFAAs and their branched isomers. Total PFAA concentrations (∑PFAAs) in the bark (mean, 279 ng/g dw) displayed a decreasing spatial trend as the distance from the FMP increased. PFAA compositional profiles in most of the tree barks were consistent to each othe. PFOA and perfluorooctane sulfonate in barks had strictly consistent isomeric compositions with their ECF products, implying that PFAAs could bind with particles and experience atmospheric transport.

Sources apportionment for perfluoroalkyl acids in the environment based on isomeric analysis

256th National Meeting (2018)

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