Associations of prenatal exposure to phthalates with measures of cognition in 4.5-month-old infants

Authors: MERCED-NIEVES, FRANCHESKA - University Of Illinois; DZWILEWSKI, KELSEY - University Of Illinois; AGUIAR, ANDREA - University Of Illinois; MUSAAD, SALMA - Children'S Nutrition Research Center (CNRC); KORRICK, SUSAN - Brigham & Women'S Hospital; SCHANTZ, SUSAN - University Of Illinois

Submitted to: International Journal of Environmental Research and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2021
Publication Date: 2/13/2021
Citation: Merced-Nieves, F., Dzwilewski, K.L., Aguiar, A., Musaad, S., Korrick, S.A., Schantz, S.L. 2021. Associations of prenatal exposure to phthalates with measures of cognition in 4.5-month-old infants. International Journal of Environmental Research and Public Health. 18(4):1838. https://doi.org/10.3390/ijerph18041838.
DOI: https://doi.org/10.3390/ijerph18041838

Interpretive Summary: Phthalates are chemicals found in a range of consumer products from food packaging to personal care products. Previous studies have found a link between phthalate exposure during pregnancy and child reasoning, behavior, and motor development. In this study, we measured different phthalates in the urine of pregnant moms. After giving birth, we measured the physical reasoning of their infants when they reached 4.5 months. During this time, infants were seated on a parent's lap while watching two videos on a television. One video was a possible event and the other was an impossible event. We measured the time it took to look at the two videos using infrared eye tracking. We found that higher exposure to monoethyl phthalate was associated with girls' increased looking time to the impossible event. In contrast, boys exposed to this and other phthalates were associated with looking longer at the possible event than the impossible event. Together these findings suggest that higher phthalate exposure during pregnancy links with worse physical reasoning in male infants. Additional research is needed to further evaluate phthalate exposure.

Technical Abstract: The association of prenatal phthalate exposure with physical reasoning was assessed in 159 (78 female; 81 male) 4.5-month-old infants from a prospective cohort. Phthalate metabolites were quantified in urine from 16–18 gestational weeks and a pool of five urines from across pregnancy. Infants' looking times to physically impossible and possible events were recorded via infrared eye-tracking. Infants that recognize that one of the events is impossible will look at that event longer. Associations of phthalate biomarkers with looking time differences (impossible–possible) were adjusted for maternal age, infant sex, and order of event presentation, and effect modification by infant sex was assessed. Each interquartile range (IQR) increase of monoethyl phthalate in the pooled sample was associated with females' increased looking time (Beta=1.0; 95%CI = 0.3, 1.7s) to the impossible event. However, for males, an IQR increase in monoethyl phthalate at 16–18 weeks (Beta=-2.5; 95%CI = -4.4,-0.6s), the sum of di(isononyl) phthalate metabolites in the pooled sample (Beta=-1.0; 95%CI = -1.8, -0.1s), and the sum of all phthalate metabolites in both samples (Beta=-2.3; 95%CI = -4.4, -0.2s) were associated with increased looking to the possible event, suggesting that higher prenatal phthalate exposure is associated with poorer physical reasoning in male infants.