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After several decades of widespread use, some per- and polyfluoroalkyl substances (PFASs) were phased-out of use due to concerns raised by their persistent, bioaccumulative, and toxic properties. Our objective was to evaluate temporal trends in serum PFAS levels among 1257 middle-aged and older California women (ages 40-94) during a four year period, beginning approximately 5-10 years after these phase-outs began. An online SPE-HPLC-MS/MS was used to measure 10 long-chain PFASs in serum from blood collected cross-sectionally during 2011-2015 from a subset of participants in the California Teachers Study. Results from multivariable linear regression analyses indicated that serum concentrations of nearly all PFASs declined on average 10% to 20% per year. Serum levels of perfluorohexanesulfonic acid (PFHxS) did not significantly decline. With the exception of PFHxS, the downward trend in serum concentrations was evident for all PFASs across all ages, although declines were comparatively steeper among the oldest women. These findings suggest that the phase-out of some common PFASs has resulted in reduced human exposures to them. The lack of a decline for PFHxS suggests that these exposures may be ongoing and underscores the importance of continued biomonitoring and research efforts to elucidate current pathways of exposure.

In response to health concerns and widespread human exposures, two widely used commercial formulations of polybrominated diphenyl ethers (PBDEs) were banned in the United States in 2005. Initial biomonitoring data have provided early indications of reduced human exposures since these bans took effect. Our objective was to evaluate temporal trends in PBDE serum levels among a population of older California women during a four-year period, beginning approximately five years after these formulations were banned. Automated solid phase extraction and gas chromatography/high resolution mass spectrometry were used to measure PBDE levels in blood collected during 2011–2015 among 1253 women (ages 40–94) participating in the California Teachers Study. Only congeners with detection frequencies (DF) ≥ 75% were included in the present analysis: BDE-47 (DF = 88%); BDE-100 (DF = 78%); and BDE-153 (DF = 80%). Results from age- and race/ethnicity-adjusted linear regression analyses indicated modest, but statistically significant, average annual percent increases in the serum concentrations of all three PBDEs over the four-year study period. While not without limitations, these results, in the context of other biomonitoring data, suggest that earlier reported declines in PBDE levels may have plateaued and may now be starting to increase. Further biomonitoring to ascertain current trends and determinants of population exposures is warranted.

As consumer products treated with polybrominated diphenyl ethers (PBDEs) reach the end of their life cycle, they often are discarded into solid-waste facilities, offering a potential reservoir for exposure. The likelihood of exposures to PBDEs by residents living near those sites rarely has been explored. This study collected blood samples from 923 female participants in the California Teachers Study in 2011-2013 and examined the association between participants' residential proximity to solid-waste facilities with potential release of PBDEs and serum levels of three congeners (BDE-47, BDE-100, and BDE-153). General linear regression analysis was used to examine the association, adjusting for age, race, body-mass index, neighborhood socioeconomic status, and urban residency. Compared to participants living10 km from any selected site, those living within 2 km had 45% higher BDE-47 (95% CI: 5-100%) and BDE-100 (95% CI: 0-109%) levels, and those living between 2 and 10 km had 35% higher BDE-47 (95% CI: 0-82%) and 29% higher BDE-100 (95% CI: -9 to 82%) levels. No associations were found for BDE-153. Living close to some solid waste sites may be related to higher serum BDE-47 and BDE-100 levels. Studies with comprehensive exposure assessments are needed to confirm these initial observations.