Half-lives of PFOS, PFHxS and PFOA after end of exposure to contaminated drinking water

Abstract

BackgroundMunicipal drinking water contaminated with perfluorinated alkyl acids had been distributed to one-third of households in Ronneby, Sweden. The source was firefighting foam used in a nearby airfield since the mid-1980s. Clean water was provided from 16 December 2013.ObjectiveTo determine the rates of decline in serum perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), and their corresponding half-lives.MethodsUp to seven blood samples were collected between June 2014 and September 2016 from 106 participants (age 4–84 years, 53% female).ResultsMedian initial serum concentrations were PFHxS, 277 ng/mL (range 12–1660); PFOS, 345 ng/mL (range 24–1500); and PFOA, 18 ng/mL (range 2.4–92). The covariate-adjusted average rates of decrease in serum were PFHxS, 13% per year (95% CI 12% to 15%); PFOS, 20% per year (95% CI 19% to 22%); and PFOA, 26% per year (95% CI 24% to 28%). The observed data are consistent with a first-order elimination model. The mean estimated half-life was 5.3 years (95% CI 4.6 to 6.0) for PFHxS, 3.4 years (95% CI 3.1 to 3.7) for PFOS and 2.7 years (95% CI 2.5 to 2.9) for PFOA. The interindividual variation of half-life was around threefold when comparing the 5th and 95th percentiles. There was a marked sex difference with more rapid elimination in women for PFHxS and PFOS, but only marginally for PFOA.ConclusionsThe estimated half-life for PFHxS was considerably longer than for PFOS and PFOA. For PFHxS and PFOS, the average half-life is shorter than the previously published estimates. For PFOA the half-life is in line with the range of published estimates.

NTP Technical Report on the Toxicity Studies of Perfluoroalkyl Sulfonates (Perfluorobutane Sulfonic Acid, Perfluorohexane Sulfonate Potassium Salt, and Perfluorooctane Sulfonic Acid) Administered by Gavage to Sprague Dawley (Hsd:Sprague Dawley SD) Rats

“…Data from 26 retired fluorochemical production workers (24 men, 2 women) indicate the average serum half-life of PFHxS is 7.3 years (8.5 years geometric mean) 35 -with a noted, although not statistically significant, higher average in women than in men (12.8 versus 8.2 years). A recent study of 106 participants of a previously exposed population found a shorter half-life of 5.3 years 36 . Similar to PFBS, these studies show a pattern of elimination rates highest in rats, lower in monkeys, and the lowest in humans.…”

Maternal serum levels of perfluoroalkyl substances in early pregnancy and offspring birth weight

“…Several PFASs are bioaccumulating, 1 and they are extremely persistent in the environment. 1 The half-lives of PFAS compounds have been estimated to be in the range of 3-5 years, 2 and some of them have been found to be transferable through the placenta. 3 Therefore, human exposure, which is shown worldwide, will continue for a long time, despite any regulations or phasing-out.…”

Application of the Key Characteristics of Carcinogens to Per and Polyfluoroalkyl Substances

“…The half-lives of individual PFAS in humans depend both on the carbon chain length and functional groups. For PFOA, PFOS and PFHxS, half-lives in humans range between 2.7 to 5.3 years [49,50]. Half-lives for shorter chain compounds, such as PFBS, are approximately one month [51].…”