Joint Associations of Prenatal Per- and Polyfluoroalkyl Substances and Metal Mixtures with Adiposity in Childhood and Adolescence.

Per- and polyfluoroalkyl substances (PFAS) and metals are ubiquitous environmental contaminants that have been individually linked to childhood adiposity, but their combined effects remain understudied. In the Project Viva cohort (n = 845), we evaluated joint associations of six first-trimester PFAS in plasma and five essential and six nonessential metals in erythrocytes with child and adolescent body mass index (BMI) z-scores and dual-energy X-ray absorptiometry (DXA) total and truncal fat mass indices. We used Bayesian kernel machine regression to evaluate joint associations of PFAS and metals with adiposity. Higher prenatal PFAS and nonessential metal mixture levels were significantly associated with higher mid-childhood and early adolescent BMI z-scores (75th vs 50th percentile: 0.17 [95% Credible Interval (CrI): 0.06, 0.28]; 0.14 [95% CrI: 0.02, 0.25]) and DXA total fat mass (0.17 kg/m2 [0.05, 0.30]; 0.20 kg/m2 [0.07, 0.32]), but not adiposity in late adolescence. Children with lower levels of the prenatal essential metal mixture had higher early and late adolescent DXA total fat mass (25th vs 50th percentile: 0.13 [0.04, 0.22]; 0.08 [0.01, 0.16]). Our findings underscore the importance of considering concurrent prenatal exposures across multiple chemical classes when evaluating environmental influences on child adiposity.