Associations between serum perfluoroalkyl acid (PFAA) concentrations and health related biomarkers in firefighters

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

“…25 However, the individual half-lives varied greatly between the firefighters, with an approximate 3.5-fold difference between the 5th and 95th percentile. 18 This variation has also been observed in and between other populations. 25 A range of factors have been suggested to explain differences in the estimated half-lives, such as menstruation, BMI, age and kidney function.…”

“…In Australian airport firefighters, the levels of "total PFOS" have decreased after the replacement of 3M-AFFF foam (the 3M-AFFF was replaced between 2002 and 2005). 18 The apparent half-life of "total PFOS" (average 6.5 years) in these firefighters was in the upper range of half-lives estimated in other observational longitudinal studies, such as in a community after the end of exposure to AFFF contaminated drinking water (average 3.4 years). 25 However, the individual half-lives varied greatly between the firefighters, with an approximate 3.5-fold difference between the 5th and 95th percentile.…”

“…40,41 Use of 3M-AFFF, historically produced by ECF, for training and firefighting events, is associated with elevated PFAS exposure in the firefighters assessed in this study; thus, ECF PFOS is believed to have been the main source of PFOS exposure in this cohort. 18,31 The proportion of L-PFOS in the serum of the firefighters (45% in 2013−2014, and 35% in 2018−2019) is significantly lower than the proportion of L-PFOS in the ECF mixture the firefighters would have been exposed to. 10 3M-AFFF usage ceased between 2002 and 2005, approximately 10 years prior to the first serum collection.…”

“…19 However, the levels of Cl−PFOS were not quantified, nor was the PFOS isomer profile determined. 18 To fully understand the PFAS exposure to firefighters, it is important to identify the full extent of PFASs that accumulate in serum. For example, it is possible that Cl− PFOS may have different physiochemical properties than non-chlorosubstituted PFOS.…”

“…The largest difference was observed for 1m-PFOS, which can be explained by the low quantified concentrations (0.31 vs 0.39 ng/mL). The sum of the quantified individual PFOS isomer concentrations (referred to as "∑PFOS isomers") in each sample was compared to the quantified "total PFOS" of the same samples from a previous analysis (quantified using mz 499/99 transition (all peaks), and linear PFOS standard) 18 and was found to be an average of 16% lower (further discussed in the Supporting Information).…”