| Risk of Birth Defects in Australian Communities with High Levels of Brominated Disinfection By-products Kimberley Chisholm,1 Angus Cook,1 Carol Bower,2,3 and Philip Weinstein1 1Environmental Determinants of Chronic Disease Group, School of Population Health, and 2Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, Perth, Australia; 3Western Australian Birth Defects Registry, Women and Infant Health Service, Perth, Australia Abstract
Background: By international standards, water supplies in Perth, Western Australia, contain high trihalomethane (THM) levels, particularly the brominated forms. Geographic variability in these levels provided an opportunity to examine cross-city spatial relationships between THM exposure and rates of birth defects (BDs) . Objectives: Our goal was to examine BD rates by exposure to THMs with a highly brominated fraction in metropolitan locations in Perth, Western Australia. Methods: We collected water samples from 47 separate locations and analyzed them for total and individual THM concentrations (micrograms per liter) , including separation into brominated forms. We classified collection areas by total THM (TTHM) concentration: low (< 60 µg/L) , medium (> 60 to < 130 µg/L) , and high (≥ 130 µg/L) . We also obtained deidentified registry-based data on total births and BDs (2000–2004 inclusive) from post codes corresponding to water sample collection sites and used binomial logistic regression to compare the frequency of BDs aggregately and separately for the TTHM exposure groups, adjusting for maternal age and socioeconomic status. Results: Total THMs ranged from 36 to 190 µg/L. A high proportion of the THMs were brominated (on average, 92%) . Women living in high-TTHM areas showed an increased risk of any BD [odds ratio (OR) = 1.22 ; 95% confidence interval (CI) , 1.01–1.48] and for the major category of any cardiovascular BD (OR = 1.62 ; 95% CI, 1.04–2.51) , compared with women living in low-TTHM areas. Conclusions: Brominated forms constituted the significant fraction of THMs in all areas. Small but statistically significant increases in risks of BDs were associated with residence in areas with high THMs. Key words: birth defects, disinfection by-products, epidemiology, pregnancy, trihalomethanes (THMs) . Environ Health Perspect 116:1267–1273 (2008) . doi:10.1289/ehp.10980 available via http://dx.doi.org/ [Online 18 April 2008]
Address correspondence to K. Chisholm, Environmental Determinants of Chronic Disease Group, School of Population Health, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia. Telephone: 61-8-6488-1266. Fax: 61-8-6488-1188. E-mail: kimberley.chisholm@gmail.com We acknowledge P. Cosgrove from the Institute of Child Health Research and the Data Linkage Unit at the Western Australia Department of Health for their assistance with data collection. We also thank the Chemistry Centre (Western Australia) , A. Jardine, and S. Joyce for their technical support. This work was performed at the School of Population Health, The University of Western Australia, Perth, Australia The authors declare they have no competing financial interests. Received 15 October 2007 ; accepted 16 April 2008. An erratum is posted online at http://www.ehponline.org/docs/2008/10980/errata.html.
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