PFOS or PreFOS? Are perfluorooctane sulfonate precursors (PreFOS) important determinants of human and environmental perfluorooctane sulfonate (PFOS) exposure?

Abstract

The extent to which perfluorooctanesulfonate precursors (PreFOS) play a role in human or environmental exposure to perfluorooctanesulfonate (PFOS) is not well characterized. The diversity of manufactured PreFOS and its degradation products (e.g. C(8)F(17)SO(2)R and C(8)F(17)SO(2)NR'R'', where R is H or F, and R' and R'' are various) has made it difficult to track their fate. Temporal trends of PFOS in both humans and wildlife are discrepant, thus it is difficult to predict future exposure, and hypotheses about the role of PreFOS have been raised. Although abiotic degradation of commercially important PreFOS materials requires further research, current data suggest that the yield of PFOS is negligible or minor. On the other hand, in vivo biotransformation of PreFOS yields PFOS as the major metabolite, and >32% yields have been observed. In Canadians, exposure to PreFOS was equivalent or greater than direct PFOS exposure prior to 2002. In most ocean water, PFOS is dominant to PreFOS, but in the oceans east of Greenland there may be more PreFOS than PFOS, consistent with the fact that whales and humans in this region also show evidence of substantial PreFOS exposure. Quantitative assessments of PFOS body-burdens coming from PreFOS are complicated by the fact that PreFOS partitions to the cellular fraction of blood, thus biomonitoring in serum under predicts PreFOS relative to PFOS. Many unknowns exist that prevent accurate modelling, thus analytical methods that can distinguish directly manufactured PFOS, from PFOS that has been biotransformed from PreFOS, should be applied in future human and environmental monitoring. Two new source tracking principles are presented and applied to human serum.

Brain region distribution and patterns of bioaccumulative perfluoroalkyl carboxylates and sulfonates in East Greenland polar bears (Ursus maritimus)

“…Perfluorooctane sulfonamide (FOSA) is the most commonly detected precursor that is degraded to PFOS [33]. It was detected in 87% of the polar bear brain samples.…”

A review of sources, multimedia distribution and health risks of perfluoroalkyl acids (PFAAs) in China

“…Telomerization produces 100% linear isomer, while electrochemical fluorination produces approximately 70-80% linear and 20-30% branched isomers (Paul et al, 2009). The less proportion of linear PFOS in serum might be used as a biomaker of exposure to PFOS-precursors (Martin et al, 2010). The temporal trend of PFAAs concentrations in three cities of China implied that concentrations of PFOS in serum have decreased, while concentrations of PFOA have increased in recent years.…”

Occurrence of organic microcontaminants in the wastewater treatment process. A mini review

“…Martin et al [96] studied the importance of the precursors on the exposure of PFOS, whose concentrations in WWTPs exceed those of its precursors by one or more orders of magnitude. PFOSA, the most frequently analysed precursor, was often found below LODs.…”