(252) Prenatal styrene and ethylbenzene exposures are associated with decreased birth weight and head circumference

Objective: Prenatal exposure to aromatic hydrocarbons has been associated with adverse health outcomes in animal studies; However, there have been limited studies of the associations between prenatal exposure to these compounds and measurable outcomes in human newborns.

Study Design: We recruited pregnant women who lived in urban areas in Israel and were admitted to the delivery rooms of two major hospitals between 2016 and 2020. The primary outcomes were newborn birthweight, length, and head circumference, measured by neonatologists in delivery rooms. Urine samples were collected from all mothers within 24 hours of admission for further BTEX analysis.

Results: A total of 883 women and their term-born infants (n(%) 462 (52%) male; mean±SD infant gestational age, 39.5±1.3 weeks) were recruited; Traces of toluene, xylene, and ethylbenzene metabolites were detected in all samples and were lower than those previously reported among worldwide population, with mean (±SD) concentrations of benzylmercapturic-acid (23.8±51.5 μg/g creatinine); methylhippuric-acid (292.5±527.2 μg/g creatinine); and phenylglyoxylic-acid (555.2±737.7 μg/g creatinine), respectively. An increase in phenylglyoxylic-acid levels was found to be associated with a decrease in males birthweight (b= -40.856 g; 95% confidence interval (CI) -73.073 to -8.639). Further exclusion of newborns considered small and large for gestational age resulted in an association between an increase in phenylglyoxylic-acid levels and head circumference of males (b= -.07 cm; 95%CI:-.146 to -.005).

Conclusion: Prenatal exposure to Styrene and Ethylbenzene in relatively low levels is associated with decreased birth weight and head circumference among males by a mechanism that is yet to be fully understood and requires further analysis.