Are PFCAs Bioaccumulative? A Critical Review and Comparison with Regulatory Criteria and Persistent Lipophilic Compounds

Abstract

Perfluorinated acids, including perfluorinated carboxylates (PFCAs), and perfluorinated sulfonates (PFASs), are environmentally persistent and have been detected in a variety of wildlife across the globe. The most commonly detected PFAS, perfluorooctane sulfonate (PFOS), has been classified as a persistent and bioaccumulative substance. Similarities in chemical structure and environmental behavior of PFOS and the PFCAs that have been detected in wildlife have generated concerns about the bioaccumulation potential of PFCAs. Differences between partitioning behavior of perfluorinated acids and persistent lipophilic compounds complicate the understanding of PFCA bioaccumulation and the subsequent classification of the bioaccumulation potential of PFCAs according to existing regulatory criteria. Based on available research on the bioaccumulation of perfluorinated acids, five key points are highlighted in this review: (1) bioconcentration and bioaccumulation of perfluorinated acids are directly related to the length of each compound's fluorinated carbon chain; (2) PFASs are more bioaccumulative than PFCAs of the same fluorinated carbon chain length; (3) PFCAs with seven fluorinated carbons or less (perfluorooctanoate (PFO) and shorter PFCAs) are not considered bioaccumulative according to the range of promulgated bioaccumulation,"B", regulatory criteria of 1000-5000 L/kg; (4) PFCAs with seven fluorinated carbons or less have low biomagnification potential in food webs, and (5) more research is necessary to fully characterize the bioaccumulation potential of PFCAs with longer fluorinated carbon chains (>7 fluorinated carbons), as PFCAs with longer fluorinated carbon chains may exhibit partitioning behavior similar to or greater than PFOS. The bioaccumulation potential of perfluorinated acids with seven fluorinated carbons or less appears to be several orders of magnitude lower than "legacy" persistent lipophilic compounds classified as bioaccumulative. Thus, although many PFCAs are environmentally persistent and can be present at detectable concentrations in wildlife, it is clear that PFCAs with seven fluorinated carbons or less (including PFO) are not bioaccumulative according to regulatory criteria.

Perfluoroheptanoic acid affects amphibian embryogenesis by inducing the phosphorylation of ERK and JNK

“…In addition, PFHxA and PFHpA considerably modulated the expression levels of various tissue-specific genes that were relevant to the observed external and internal phenotypes. In particular, xPTB was used as a liver-specific marker and the protein encoded by this gene complexes with the LDL receptor to mediate hepatic LDL removal by endocytosis (35,36). Consistent with other reports, the xPTB mRNA levels were considerably modulated following exposure to either PFHxA or PFHpA (16).…”

“…Several studies have examined the toxicity of different PFC in many aquatic and other animals (24,32,33). These studies have confirmed that exposure during particular developmental stages or under certain nutritional conditions produced adverse effects on neonates (34,35). Amphibians are more sensitive to environmental exposures during the fetal stage.…”

Tissue Distribution and Whole Body Burden of the Chlorinated Polyfluoroalkyl Ether Sulfonic Acid F-53B in Crucian Carp (Carassius carassius): Evidence for a Highly Bioaccumulative Contaminant of Emerging Concern

“…51 Because of the lack of a suitable normalization criteria for PFASs, such as total lipid weight for neutral organic chemicals, BAFs have sometimes been reported for individual tissues. 16 Median log BAF tissue values for F-53B varied considerably among the different tissues, ranging from 3.80 to 5.23 for TL, and 3.92 to 5.01 for XR, but were consistently higher than ones for PFOS (see also Table S10). However, for assessment of the bioaccumulation potential compared to regulatory criteria, whole body concentrations should be used because concentrations in most measured tissues would overestimate bioaccumulation potential.…”

“…16 Unlike most persistent organic pollutants, perfluoroalkyl acids do not partition into storage lipids due to the dipolar nature of the carbon−fluorine bond and their anionic headgroup. 16 Instead, specific protein-binding mechanisms and/or partitioning to phospholipids have been proposed to explain the surprisingly high bioaccumulation potential of some PFASs.…”

Ferric ion mediated photochemical decomposition of perfluorooctanoic acid (PFOA) by 254nm UV light

“…pressure 0.49 MPa and pH 1.5. PFOA is more widely detected in the environment than other PFCAs, and bioaccumulation of PFCAs is directly related to length of perfluorinated carbon-chain [29,30]. It is more necessary and valuable to know whether and how PFOA is decomposed.…”