MATERNAL EXPOSURE TO WATER DISINFECTION BY-PRODUCTS AND ADVERSE BIRTH, NEONATAL AND EARLY CHILDHOOD OUTCOMES

Abstract

ISEE-238 Aim: This study forms part of a PhD designed to test the hypothesis that there is a positive association between adverse birth, neonatal and early childhood outcomes and disinfection by-product (DBP) exposure. This registry-based prevalence study specifically explores the association between birth defects and residence in areas supplied with public drinking water containing high trihalomethane (THM) levels. Background: DBPs, which are produced during the disinfection of public water supplies, have been implicated as risk factors for adverse reproductive outcomes. In comparison to other states of Australia, Western Australia (WA) has a higher prevalence of birth defects, and it has been hypothesised that environmental influences (such as variable water quality) may be important in the etiology of these disorders. The water supply to the main metropolitan area, Perth, is known to contain high levels of organic precursor molecules (e.g. fulvic and humic acid from soils) that react with chemical disinfectants to produce DBPs, including trihalomethanes (THMs). Routine water sampling has confirmed that THM levels are high in the residential water supplies for a number of suburbs, with levels often exceeding 100 micrograms/L (considered a high level in some studies). Methods: The numbers of birth defects by suburb were identified for the years 2002–2003 through the Western Australia Birth Defects Registry. This registry has a high degree of completeness and accuracy for birth defects occurring in the Perth metropolitan area. To estimate the DBP exposure in the study population, we obtained recent THM data from several Perth suburbs, recorded during routine surveillance and monitoring. Suburbs were classified as high or low THM exposure, with high THM defined as concentrations exceeding 100 microgams/L. The analysis included calculation of the relative risk of birth defects per woman of reproductive age, resident in areas with high versus low THM levels. Results: Our preliminary data indicate that women of reproductive age, resident in confirmed high THM suburbs are 26% more likely to have a child with a birth defect compared to those resident in the largest low THM suburb. This possible relationship between THM and birth defects requires further investigation.