Understanding prenatal household exposures to per- and polyfluorylalkyl substances using paired Biological and dust measurements with sociodemographic and housing variables.

Per- and poly-fluoroalkyl substances (PFAS) are chemicals of concern-they are ubiquitous, persistent, with known and suspected health impacts. Well studied, primary sources of exposure to PFAS are drinking water and food. The presence of PFAS in human tissue of general populations suggests other important exposure sources/pathways. House dust measurements suggest widespread presence of PFAS in residences. Limited studies report paired analyses of PFAS occurrence in indoor media and PFAS concentrations in serum. While paired samples of house dust and blood serum are currently rare, the National Children's Study (NCS) contains paired samples, as well as sociodemographic information, from pregnant people that participated in the study. These archived NCS data and specimens for 104 participants collected between 2009 and 2014 were leveraged and analyzed for 16 commonly measured PFAS. We evaluated PFAS levels in the home, and the relationships between PFAS in dust and serum, and sociodemographic or housing variables. In addition, mechanistic exposure models, and then steady-state serum level models with simple parameters were used to estimate dust contributions of PFAS to serum. The geometric means for the most commonly found PFAS (full names in table 1) in serum were: 4.1 ng/mL for PFOS, 1.1 ng/mL for PFOA, 0.87 ng/mL for PFHxS, 0.16 ng/mL for PFDA. The geometric means of PFAS in dust were: 17 µg/kg for PFOS, 16 µg/kg for PFOA, 9.6 µg/kg for PFDS, 4.5 µg/kg for PFHpA, 4.4 µg/kg for PFNA, 3.9 µg/kg for PFHxS, 3.5 µg/kg for PFDA, 2.3 µg/kg for PFDoA, 2.1 µg/kg for PFUdA. PFOA was significantly correlated in serum and dust as was the sum of all PFAS detected in > 50 % of serum and dust. PFAS in serum was significantly associated with: Higher income, recent renovations, years lived in the home, and educational attainment. PFAS in dust was significantly associated with: Higher participant age, type of home, amount of carpet, educational attainment, higher income, recent renovation, and membership in the military. For some PFAS, 25 % of the overall exposure, on average, is from dust, but for others, 3-4 % is attributed to dust. We were able to identify important associations in PFAS exposure in the homes of pregnant people based on paired serum and dust samples. This built a clearer picture of which PFAS and at what quantities they exist in these homes, how they relate to each other, and how they are tied to sociodemographic and housing factors. Our results demonstrate that exposure to PFAS via house dust may contribute up to 25% of total exposure for adults, highlighting the importance of understanding what drives residential exposures.