Chlorination Disinfection By-Products and Risk of Congenital Anomalies in England and Wales

Abstract

BackgroundIncreased risk of various congenital anomalies has been reported to be associated with trihalomethane (THM) exposure in the water supply.ObjectivesWe conducted a registry-based study to determine the relationship between THM concentrations and the risk of congenital anomalies in England and Wales.MethodsWe obtained congenital anomaly data from the National Congenital Anomalies System, regional registries, and the national terminations registry; THM data were obtained from water companies. Total THM (< 30, 30 to < 60, ≥60 μg/L), total brominated exposure (< 10, 10 to < 20, ≥20 μg/L), and bromoform exposure (< 2, 2 to < 4, ≥4 μg/L) were modeled at the place of residence for the first trimester of pregnancy. We included 2,605,226 live births, stillbirths, and terminations with 22,828 cases of congenital anomalies. Analyses using fixed- and random-effects models were performed for broadly defined groups of anomalies (cleft palate/lip, abdominal wall, major cardiac, neural tube, urinary and respiratory defects), a more restricted set of anomalies with better ascertainment, and for isolated and multiple anomalies. Data were adjusted for sex, maternal age, and socioeconomic status.ResultsWe found no statistically significant trends across exposure categories for either the broadly defined or more restricted sets of anomalies. For the restricted set of anomalies with isolated defects, there were significant (p < 0.05) excess risks in the high-exposure categories of total THMs for ventricular septal defects [odds ratio (OR) = 1.43; 95% confidence interval (CI), 1.00–2.04] and of bromoform for major cardiovascular defects and gastroschisis (OR = 1.18; 95% CI, 1.00–1.39; and OR = 1.38; 95% CI, 1.00–1.92, respectively).ConclusionIn this large national study we found little evidence for a relationship between THM concentrations in drinking water and risk of congenital anomalies.

The epidemiology and possible mechanisms of disinfection by-products in drinking water

“…Few studies have been published on chlorinated water and respiratory congenital anomalies, but two studies found a significant positive association (Aschengrau et al 1993;Hwang et al 2002), whereas two did not (Chisholm et al 2008;Nieuwenhuijsen et al 2008).…”

“…A number of studies have found statistically significant positive associations between THMs and neural tube defects (NTDs), one of the most studied groups of congenital anomalies (Bove et al 1995;Klotz & Pyrch 1999;Dodds & King 2001), whereas other studies have not found statistically significant associations (Dodds et al 1999;Magnus et al 1999;Källen & Robert 2000;Hwang et al 2002;Shaw et al 2003;Nieuwenhuijsen et al 2008) (table 2). Klotz & Pyrch (1999) found a statistically significant association between total THM (TTHM) levels in the water and NTDs, but not with levels of haloacetonitriles and HAA.…”

“…For example, studies on SGA/IUGR by Dodds et al (1999), Wright et al (2003Wright et al ( , 2004 and Hinckley et al (2005), on congenital anomalies by Hwang et al (2002Hwang et al ( , 2008 and Nieuwenhuijsen et al (2008) and on stillbirth by Toledano et al (2005) provide sufficiently large numbers of cases to create various exposure categories with more robust risk estimates, which could improve the overall assessment of risk.…”

“…Some studies have examined individual (brominated) THM species (e.g. Waller et al 1998;King et al 2000b;Dodds & King 2001;Shaw et al 2003;Dodds et al 2004;Wright et al 2004;Nieuwenhuijsen et al 2008). In addition, some studies have investigated other DBPs such as HAAs and/or MX (e.g.…”

Spatial and temporal evaluations of disinfection by-products in drinking water distribution systems in Beijing, China

“…However, chlorine can also react with natural materials in the raw water to form disinfection by-products (DBPs) that are hazardous to health (White, 1992;WHO, 2004;Uyak et al, 2008). Some epidemiologic studies (IARC, 1991;WHO, 1996;Singer, 1999;Magnus et al, 1999;Nieuwenhuijsen et al, 2008) have shown an association between long-term exposure to disinfection by-products and increased risk of cancer and potential adverse reproductive effect. Trihalomethanes (THMs) and haloacetic acids (HAAs) are the most important groups of DBPs in chlorinated finished water.…”