Apparent Half-Lives of Chlorinated-Perfluorooctane Sulfonate and Perfluorooctane Sulfonate Isomers in Aviation Firefighters

Abstract

Elevated levels of perfluorooctane sulfonate (PFOS) and elevated detection frequency of chloro-substituted PFOS have been reported in Australian firefighters with historical exposure to aqueous-film forming foam (AFFF). The aim of this study is to estimate the apparent half-lives of Cl–PFOS and PFOS isomers in firefighters following the end of exposure to 3M-AFFF. Paired serum samples from 120 firefighters, collected approximately five years apart, were analyzed for 8-Cl–PFOS (8-chloroperfluoro-1-octanesulfonic acid) and PFOS isomers via targeted LC–MS/MS. Apparent half-life was estimated by assuming a first order-elimination model. Cl–PFOS was detected in 93% of all initial serum samples (<LOQ–1.09 ng/mL). The average half-life of Cl–PFOS among the firefighters was 5.0 years. Branched PFOS isomers made up 55% of the total isomer concentration at the initial sampling timepoint. Five years later, the proportion of branched PFOS isomers was greater (65%). The longest average half-life (11.5 years) was estimated for “1m-PFOS”. Other isomers had average half-lives ranging from 4.0 to 7.5 years. Marked differences in half-lives between PFOS isomers suggest that the elimination rate of “total PFOS” (sum of all PFOS isomers) is non-linear. This is the first study to report the serum concentrations and apparent half-life of Cl–PFOS in humans.

Legacy and Emerging Per- and Polyfluoroalkyl Substances in a Subtropical Marine Food Web: Suspect Screening, Isomer Profile, and Identification of Analytical Interference

“…Cl-PFOS was found to have comparable bioaccumulation potential and similar tissue-distribution characteristics with PFOS in fish and exhibited a strong persistence in human blood (estimated half-life: 5.0 years) . Nevertheless, the source of Cl-PFOS is still unclear, and the occurrence of Cl-PFOS in wildlife was not reported until 2020. , Hence, more investigation on Cl-PFOS in biota is necessary, and the influence of the analytical interfering substance should attract broader attention. Moreover, it is possible that Cl-PFOS exists as several different isomers, any one of which can be misidentified as Cl-PFOS identity, especially for isomer-specific studies.…”

“…For the analysis of Cl-PFOS, 514.9 → 79.9 (nominal C 8 F 16 ClSO 3 – → SO 3 – ) and 514.9 → 98.9 (nominal C 8 F 16 ClSO 3 – → FSO 3 – ) are the most commonly used transition pair because they have been found to have higher signal than other transitions ( Figure S4 ). 31 , 45 − 47 The “suspected Cl-PFOS” compound was detected in both two transitions, and this compound has a close retention time to that of the Cl-PFOS identity (the retention time intervals between these two compounds were 0.2 min for the C18 column and 0.07 min for the PFP column). This “suspected Cl-PFOS” compound was then re-analyzed via HRMS for identification.…”

“… 45 Nevertheless, the source of Cl-PFOS is still unclear, and the occurrence of Cl-PFOS in wildlife was not reported until 2020. 45 , 46 Hence, more investigation on Cl-PFOS in biota is necessary, and the influence of the analytical interfering substance should attract broader attention. Moreover, it is possible that Cl-PFOS exists as several different isomers, 48 any one of which can be misidentified as Cl-PFOS identity, especially for isomer-specific studies.…”

Method Validation for Quantification of PFOS and PFOA in Human Plasma and a Pilot Study in Blood Donors from Thai Red Cross Society

“…Meanwhile, nearly 96.71% of the L–PFOS isomer was found in the serum of middle-aged Taiwanese adults [ 34 ]. Interestingly, the average L–PFOS isomer proportion found in the serum samples of aviation firefighters from Australia with historical exposure to aqueous-film-forming foam was only 35% [ 35 ]. Consequently, differences in the PFOS isomer composition should be considered in the interpretation of any PFAS-related results, as the health outcomes could vary greatly for certain study populations.…”

Sensor technologies for the detection and monitoring of endocrine-disrupting chemicals

“…Perfluorooctane sulfonate (PFOS) was widely used in stain-resistant fabrics, fire-fighting foams, food packaging, and as a surfactant in industrial processes, and PFOS can also be generated in the environment after release and transformation of precursors ( Kancharla et al, 2022 ; Nilsson et al, 2022 ). Although no longer produced in the United States, PFOS remains an environmental contaminant and is still being produced and used in products internationally ( Pontius, 2019 ).…”