Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August-1 September 2010: Reproductive Health and Environment
Experimental data suggest that chlorite and chlorate, the main disinfection by-products when chlorine dioxide are used, which can be related to the developmental toxicity, however, no epidemiological evidence is available. This study is a part of the international project “HiWate” (Health Impacts of Long-Term Exposure to Disinfection By-Products in Drinking Water), funded under the EU Sixth Framework Programme for Research and Technological Development (FP6), and aimed to evaluate the risk of congenital anomalies related to chlorite and chlorate exposure during pregnancy.
A case-control study was carried out in a Northern Italy region (Emilia-Romagna). During the study period (2002–2005), newborns with different congenital anomalies (neural tube, cardiovascular, abdominal wall, cleft lip and palate, respiratory, genital organs, and urinary tract defects) or chromosomal anomalies were extracted from the Regional Malformation Registry, whereas controls (newborns without malformations) were randomly selected from the Regional Birth Register. On the basis of each mother's address, the network supplying drinking water during the period of interest (first trimester of pregnancy) was identified: data on disinfection, water quality, and disinfection by-products were linked to each subject.
Chlorite levels were available for 5494 subjects (mean value: 427 ± 184 μg/L; range: <200–1283 μg/L); chlorate levels were available for 1178 women (mean value: 283 ± 78 μg/L; range: <200–1140 μg/L). In comparison to subjects exposed to levels <200 μg/L, women exposed to chlorite level >700 μg/L resulted, after adjusting for personal, reproductive, and socioeconomic confounders, at higher risk of newborns with renal defects (OR: 3.3; 95% CI: 1.4–8.1), abdominal wall defects (OR: 6.9; 95% CI: 1.7–28), cleft palate (OR: 4.1; 95% CI: 0.98–16.8); whereas women exposed to chlorate level >200 μg/L resulted at higher risk of newborns with obstructive urinary defects (OR: 2.9; 95% CI: 1.1–7.6) and spina bifida (OR: 4.94; 95% CI: 1.1–22).
This was the first epidemiological study evaluating the relationship between chlorite and chlorate exposure and congenital anomalies, however, despite of the ecological exposure assessment, significant increased risks were observed, mainly for urinary tract defects.