Multi-pollutant effects of prenatal heavy metal exposure on atopic dermatitis in 6-month-old infants

Abstract

Background: Prenatal exposures to endocrine-disrupting chemicals during critical developmental phases have been implicated in the development of the immune system and allergic phenotypes. However, there are few studies associating prenatal heavy metal exposure with atopic dermatitis (AD) in infants according to their sex. Objective: We aimed to examine prenatal exposure to multiple heavy metals with sex-specific AD incidence in 6-month-old infants using data from the Mothers and Children’s Environmental Health (MOCEH), a prospective birth cohort study. Methods: We evaluated 738 mother-child pairs from the MOCEH study. Concentrations of three heavy metals (mercury, lead, and cadmium) in maternal blood samples were measured at early and late pregnancy. Each quantile of heavy metal concentration was used for capturing nonlinear association with AD. To account for selection bias caused by loss to follow-up, we generated an inverse probability of censoring weight (IPCW). Furthermore, the group Lasso model with IPCW was used to perform variable selection with categorized exposures and assess the effect of multiple pollutants with selected exposures, and its optimal lambda was estimated by 5-fold cross-validation. 95% confidence intervals (CIs) were estimated by bootstrap method. Exposures in early and late pregnancy were simultaneously included in the model to identify the susceptible window. Results: A total of 200 incident cases of AD were diagnosed in 6-month-old infants. In late pregnancy model of the boy group, lead and mercury exposures were selected, and adjusted odds ratios (ORs) comparing the second, third and fourth quartiles of lead exposure with the first quartile group were 1.155 (95% CI: 0.965, 5.619), 1.097 (0.924, 5.715), and 1.191 (1.138, 8.390), respectively. However, no significant associations were observed in the girl group. Conclusion: Our findings suggest that lead exposure in late pregnancy may be independently associated with a higher risk of AD in 6-month-old boys.