Maternal periconceptional exposure to drinking water disinfection by-products and neural tube defects in offspring

Background

Associations between maternal periconceptional exposure to disinfection by-products (DBPs) in drinking water and neural tube defects (NTDs) in offspring are inconclusive, limited in part by exposure misclassification.

Methods

Maternal interview reports of drinking water sources and consumption from the National Birth Defects Prevention Study were linked with DBP concentrations in public water system monitoring data for case children with an NTD and control children delivered during 2000–2005. DBPs analyzed were total trihalomethanes, the five most common haloacetic acids combined, and individual species. Associations were estimated for all NTDs combined and selected subtypes (spina bifida, anencephaly) with maternal periconceptional exposure to DBPs in public water systems and with average daily periconceptional ingestion of DBPs accounting for individual-level consumption and filtration information. Mixed effects logistic regression models with maternal race/ethnicity and educational attainment at delivery as fixed effects and study site as a random intercept were applied.

Results

Overall, 111 case and 649 control children were eligible for analyses. Adjusted odds ratios for maternal exposure to DBPs in public water systems ranged from 0.8–1.5 for all NTDs combined, 0.6–2.0 for spina bifida, and 0.7–1.9 for anencephaly; respective ranges for average daily maternal ingestion of DBPs were 0.7–1.1, 0.5–1.5, and 0.6–1.8. Several positive estimates (≥1.2) were observed, but all confidence intervals included the null.

Conclusions

Using community- and individual-level data from a large, US, population-based, case–control study, we observed statistically nonsignificant associations between maternal periconceptional exposure to total and individual DBP species in drinking water and NTDs and subtypes.