Lead levels in domestic water supplies and neural tube defects in Glasgow

Objective-To study the association between ((pregnancy)) prevalence (affect ed births and terminations) of neural tube defects in postcode districts of Glasgow and lead concentrations in domestic water. Setting-Postcode districts of Glasgow supplied by water from the Loch Katri ne reservoir. Design-An ecological study. Lead concentrations from 1911 randomly selected domestic water samples were obtained from the Glasgow 93 lead study. Neura l tube defects (affected births and terminations) were identified from the Glasgow register of congenital anomalies for the period 1983-95 for each po stcode district in the study population. Correlations were sought between l ead concentrations and pregnancy prevalence of neural tube defects/1000 liv e births in postcode districts. Results-No correlation was found between domestic water lead concentrations > 10 mu g/litre and pregnancy prevalence of neural tube defects within pos tcode districts. Areas of Glasgow previously with high domestic water lead concentrations did not have a higher prevalence of neural tube defects. Hou ses with the lowest domestic water lead concentrations were in Carstairs de privation categories 1 (least deprived), 6, and 7 (most deprived). The high est pregnancy prevalence of neural tube defects was found in the most depri ved areas. Conclusion-Deprivation is a risk factor for neural tube defects and might h ave been a confounding factor in previous studies looking at the associatio n between such defects and domestic water lead concentrations. This study d oes not support the hypothesis that levels of lead > 10 mu g/litre in domes tic water supplies are associated with a higher pregnancy prevalence of neu ral tube defects. The reasons behind the decline in pregnancy prevalence of neural tube defects seen in the past two decades remain unexplained.