Abstract:
Increased risk of spontaneous abortion (SAB) is possibly associated with nitrate exposures in drinking water. However, available data are insufficient to establish whether an association exists. This study evaluated the feasibility of a case-control design using postal questionnaires and existing water quality data to investigate the risk of SAB associated with nitrate exposure in drinking water. The questionnaires were evaluated for rates, completeness and validity of responses. Water nitrate data were evaluated for sampling frequency, consistency, and compared to the nitrate maximum contaminant level (MCL). The questionnaire was effective in obtaining essential information from all subjects. Limited nitrate data was available for 29% of private wells. Nitrate data of varying frequency were available for eighty-eight percent of Group A water systems. Eighty-six percent of subjects with private wells drank directly from the tap without knowing the water quality. Forty percent of cases versus thirteen percent of controls used private wells (P=0.085). This method is not feasible because existing water quality data are inadequate for retrospectively determining nitrate exposures during a particular pregnancy. Increased efforts are needed to educate the public about potential contamination of private well water by nitrates or other contaminants and the associated potential health risks. Additional studies, that include subjects who obtain their drinking water from private wells, are needed to investigate the possible association between the risk of SAB and nitrate exposure from drinking water.