Haloacetic acids in public drinking water and risk of adverse birth outcomes in the 'Born in Bradford' cohort

• Main Author: Edwards, Susan
• Other Authors: Toledano, Mireille ; Best, Nicky ; Nieuwenhuijsen, Mark
• Published: Imperial College London 2014
• Subjects: 628.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705756

Disinfection of drinking water is vital to protect the public against disease. However disinfectants such as chlorine react with organic matter in drinking water to produce a wide range of chemical disinfection by-products (DBPs) of potential health concern including haloacetic acids (HAAs). This thesis is an epidemiologic analysis investigating the relationship between prenatal exposure to HAAs in drinking water and adverse birth outcomes in 'Born in Bradford', a large multi-ethnic prospective birth cohort study based in Bradford, England. It focuses on the understudied and as yet unregulated HAAs which are the second most prevalent class of chlorination DBPs in UK drinking waters. To assess exposure, area-level concentrations to three select HAAs (measured in drinking water samples newly collected for this study, modelled in time and space, and weighted to each cohort woman's specific trimester of pregnancy by postcode of residence) were combined with individual water consumption information collected via questionnaire at recruitment to the cohort. Despite the benefits of state-of-the-art exposure metrics and a large sample size, this study does not find any significant patterns of association between prenatal exposure to HAAs and either birth weight, being born term low birth weight or small-for-gestational age. Water consumption over the course of late pregnancy was further studied in a subset of cohort women. A small but significant increase in water consumption was reported, bearing in mind that both behaviour change over the third trimester of pregnancy and measurement error likely contributed to this effect. This research addresses some of the limitations of previous DBP studies in terms of exposure assessment and birth outcome definitions, and uniquely evaluates the variability of individual water consumption over time. It also identifies areas for future research and examines the importance of HAAs and birth weight-based outcomes in the larger research context.