Historical human exposure to perfluoroalkyl acids in the United States and Australia reconstructed from biomonitoring data using population-based pharmacokinetic modelling
(English)Manuscript (preprint) (Other academic)
Perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS) and perfluorohexane sulfononic acid (PFHxS) have been found in human serum worldwide. Since the beginning of the 21st century, a downward trend in the human body burden, especially for PFOS and PFOA, has been observed while there is no clear trend in wildlife. The inconsistency between the concentration decline in human serum and in wildlife could be indicative of a historical exposure pathway for humans linked to consumer products that has been reduced or eliminated. In this study, we investigate the past human exposure trends in two different regions, USA and Australia, by reconstructing the historical intake from cross-sectional biomonitoring data of PFOS and PFOA using a population-based pharmacokinetic model. For PFOS in the USA , the reconstructed daily intake peaked at 4.5 ng/kg-bw/day between 1988 and 1999; and in Australia it was 4.0 ng/kg-bw/day between 1984 and 1996. For PFOA in USA and Australia, the peak reconstructed daily intake was 1.1 ng/kg-bw/day in 1995 and 3.6 ng/kg-bw/day in 1992, respectively, and started to decline in 2000 and 1995, respectively. The model could not be satisfactorily fitted to the biomonitoring data for PFHxS within reasonable boundaries for its intrinsic elimination half-life, and thus reconstructing intakes of PFHxS was not possible. Our results indicate that humans experienced similar exposure levels and trends to PFOS and PFOA in the USA and Australia. Our findings support the hypothesis that near-field consumer product exposure pathways were likely dominant prior the phase-out in industrialized countries. The intrinsic elimination half-life, which represents elimination processes that are common for all humans, and elimination processes unique to women (i.e., menstruation, cord-blood transfer and breast feeding) were also investigated. The intrinsic elimination half-lives for PFOS and PFOA derived from model fitting for men were 4.9 and 2.4 years, respectively, for the USA, and 3.8 and 2 years respectively for Australia. The elimination half-lives in women were up to 15% lower for PFOS and up to 12% lower for PFOA. =Our results show that menstruation is a depuration pathway for PFOA for women, similarly but to a lesser extent compared to previous reports for PFOS. However menstruation, cord-blood transfer and breast feeding together do not fully explain the apparently more rapid elimination of PFOA and PFOS by women compared to men.
PFOS, PFOA, PFHxS, Human exposure, population, Australia, USA, pharmacokinetic model
Research subject Applied Environmental Science
IdentifiersURN: urn:nbn:se:su:diva-141081OAI: oai:DiVA.org:su-141081DiVA: diva2:1085752