Half-lives of several polyfluoroalkyl substances (PFAS) in cattle serum and tissues.

Cattle that were at steady-state serum polyfluoroalkyl substances (PFAS) concentrations due to several years of exposure to water contaminated by residues of Aqueous Film-Forming (AFFF) firefighting foam had perfluorooctane sulphonate (PFOS) isomers, perfluoroheptane sulphonate (PFHpS), perfluorohexane sulphonate (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) in serum. Elimination serum half-lives were determined in five heifers from serial blood sampling over 215 days. Eleven additional animals that had blood sampled on day 19 (d19) were euthanised on d63. PFAS half-life estimates from the serial blood sampling and from d19/d63 data were not significantly different. The combined (n = 16) serum half-lives (in days) were: total PFOS (tPFOS, 74.1 ± 13.4), PFHpS (45.7 ± 9.4), PFHxS (9.3 ± 1.3), PFNA (12.3 ± 3.2) and PFDA (60.4 ± 10.4). The half-lives of linear PFOS (L-PFOS, 69.4 ± 11.6) and mono branched PFOS isomers (m-PFOS, 83.6 ± 19) were not significantly different from tPFOS, but for the di-branched isomers (di-PFOS), the serum half-life was significantly lower (29.9 ± 5.8). Animal age (1.4-12.3 years old) and serum concentration at the start of depuration did not influence half-lives, and there was no difference between steers and heifers. Consideration of serum and tissue PFAS concentrations at d63 and d215 indicated there was no difference in tPFOS depuration from serum or muscle, but elimination from liver and kidney may be slightly longer. Depuration of PFHpS is essentially the same in serum, kidney and liver, and it is expected depletion from muscle would be comparable. The short half-life of di-PFOS, PFHxS and PFNA did not allow an assessment of clearance from tissues because they were not measurable at d215 but based on the results for PFOS and PFHpS, elimination of PFHxS from tissues is expected to mirror that from serum. Human health risk assessment implications are discussed.

Accumulation of PFAS by livestock - determination of transfer factors from water to serum for cattle and sheep in Australia.

In this study accumulation has been determined of several per- and polyfluoroalkyl substances (PFAS) from ingested water to steady state serum concentration for adult beef cattle and sheep raised on a hobby farm impacted by PFAS contamination. PFAS concentrations in stock water were stable for more than a year, they were non-measurable in grass but present at very low levels in soil which equated to just 1% of the intake from water. Prior to quantifying PFAS in cattle serum there had been no breeding for 18 months. Although there were high concentrations of several PFAS in the water, only perfluorooctane sulphonate (PFOS) and perfluorohexane sulphonate (PFHxS) were in cattle serum in appreciable amounts; perfluoroheptane sulphonate (PFHpS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were much lower. Transfer factors (TFs) for cattle were calculated by dividing steady state serum concentration (ng PFAS/mL) by water concentration (µg PFAS/L). Average and upper estimate TF values for cattle were calculated; the former were 140 (total PFOS, i.e. tPFOS), 130 (PFHpS), 65 (PFHxS), 170 (PFNA), and 120 (PFDA). Previous investigation campaigns at the farm provided relative steady state serum PFAS concentrations for sheep and cattle that allowed adjustment of the cattle TFs. The resulting average estimate TFs for ewes (non-pregnant and not lactating) were 20 (tPFOS) and 30 (PFHxS), other PFAS were not measurable in sheep serum. Discussion on using these TFs in human health risk assessments is provided. With certain assumptions/caveats the TFs allow estimations of PFAS steady state serum concentrations for use in preliminary human health risk assessments (HHRAs) when only PFAS in stock water is known.

Per- and polyfluoroalkyl substances (PFAS) in livestock and game species: A review.

Per- and polyfluoroalkyl substances (PFAS) are synthetic, organic chemicals that resist environmental breakdown. The properties that made PFAS into an industrial success also led to their persistence and bioaccumulation. As PFAS were widely used for many decades their presence is evident globally, and their persistence and potential for toxicity create concern for human, animal and environmental health. Following the precautionary principle, a reduction in human exposure is generally recommended. The most significant source of human exposure to PFAS is dietary intake (food and water) with additional exposure via dust. As PFAS concentrations have been more frequently studied in aquatic food sources, there is less understanding of exposure via terrestrial animals. To further define human exposure via animal products, it is necessary to determine PFAS concentrations and persistence in terrestrial livestock and game species. Studies assessing ambient concentrations of PFAS have noted that, aside from point sources of contamination, there is generally low input of PFAS into terrestrial agricultural food chains. However, livestock and game species may be exposed to PFAS via contaminated water, soil, substrate, air or food, and the contribution of these exposures to PFAS concentrations in food products is less well studied. This review focuses on perfluoroalkyl substances (PFAAs) and compiles information from terrestrial livestock and game species as a source of dietary exposure in humans, and discusses toxicokinetics and health effects in animals, while identifying future focus areas. Publications describing the transfer of PFAAs to farmed and hunted animals are scarce, and demonstrate large variability in distribution and elimination. We outline several relatively small, short-term studies in cattle, sheep, pigs and poultry. While negative effects have not been noted, the poultry investigations were the only studies to explicitly assess health effects. Comparative information is presented on PFAA concentrations in livestock products and edible tissues of game animals.