Serum concentrations of legacy, alternative, and precursor per- and polyfluoroalkyl substances: a descriptive analysis of premenopausal participants in the Canadian CARTaGENE cohort

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Abstract Background Human biomonitoring studies of per- and polyfluoroalkyl substances (PFAS) have typically focused on legacy PFAS. Data for alternative and precursor PFAS are emerging, but are still scarce. These data are critical for assessing exposure and human health risk. Methods We measured serum concentrations of 40 PFAS among 2,775 premenopausal participants from the CARTaGENE cohort (Phase A: 2009–2010; Phase B: 2013–2014). We examined differences in geometric mean serum concentrations of PFAS with > 60% detection, as well as the sum of 7 PFAS (Σ7PFAS), across categories of sociodemographic, lifestyle, and reproductive history characteristics. Results Eight PFAS were detected in > 60% of participants. Geometric mean serum concentrations ranged from 0.03 µg/L (PFHpS and MeFOSAA) to 4.25 µg/L for PFOS and 8.00 µg/L for Σ7PFAS. The largest differences in serum PFAS concentrations were observed across reproductive history characteristics. Concentrations of PFOS, PFNA, PFOA, PFHxS, and the Σ7PFAS were monotonically lower with each additional child birthed, higher with increasing time since last pregnancy, and lower among those with a history of breastfeeding. The PFAS reducing effect of parity appeared to outweigh the bioaccumulative effect of age for most legacy PFAS. Concentrations of PFOS, PFNA, PFOA, PFHxS, PFDA, PFUnA and the Σ7PFAS were lower among participants with a reported household income below the Canadian low-income cut-off. Several alternative and precursor PFAS were detected in this population, including sulfonamidoacetic acids, sulfonamides, fluorotelomers, and fluoroethers, but serum concentrations were relatively low, with 95 th percentiles < 0.5 µg/L. Conclusions This work contributes to expanding human biomonitoring data beyond legacy PFAS, and our findings suggest that exposure to low levels of some alternative and precursor PFAS may be widespread in Canada. These results also reinforce the role of pregnancy and breastfeeding as excretion pathways for legacy PFAS and support previous investigations demonstrating that exposure to some PFAS may be lower amongst financially disadvantaged populations.