Prenatal exposure to organophosphate esters (OPEs) and infant attention to faces at age 1 month

BACKGROUND: Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers. Prenatal OPE exposure has been associated with adverse childhood neurodevelopment, but these outcomes are not often evaluated until well into childhood. We leveraged infants' innate preference for faces to evaluate gestational OPE exposure in relation to an early measure of cognitive processing. METHODS: We measured nine mid-pregnancy urinary OPE metabolites in a U.S. UPSIDE pregnancy cohort (n = 166). At age 1 month, infants were presented with a randomized series of three face-like images: standard features, scrambled features, and a featureless face shape. Using latent profile analysis, we identified three looking profiles (short, long, and selective lookers). We evaluated associations with OPE metabolites using multivariable multinomial logistic models. OPEs with > 70% detection were considered continuously; less prevalent OPEs were dichotomized. RESULTS: Infants of mothers with detectable bis(2-methylphenyl) phosphate had greater odds of being long vs. short lookers (OR: 2.80, 95% CI: 0.99, 7.96), with stronger associations observed among females. Among boys, higher maternal dibutyl phosphate + di-isobutyl phosphate exposure was associated with 6 times the odds of being a long looker (OR: 6.05, 95%CI: 1.05, 34.92). Among girls, detectable maternal dipropyl phosphate was associated with lower odds of being a long (OR: 0.01, 95% CI: 0.001, 0.75) or a selective looker (OR <0.001, 95% CI: <0.001, 0.05). CONCLUSION: Prenatal OPE exposure may influence early face-processing, potentially in a sex-dependent manner. Follow-up is needed to assess this measure's ability to predict downstream neurodevelopmental outcomes.