Fluoride Action Network


The relation between fluoride level in drinking water and the incidence of congenital heart disease in Iowa was studied by means of a hybrid case-control design. Controls (n = 2,172) were randomly selected from the birth tapes of the State of Iowa between January 1, 1983 and December 31, 1987, and frequency matched by time of conception with cases of intracardiac blood flow defect (n = 543) ascertained through the Birth Defects Registry of lowa. Potential confounding factors included levels of nitrate in drinking water, chlorination status and source of drinking water, demographic characteristics of parents, gestational age, and birth weight of infants. Logistic regression analysis yielded an adjusted odds ratio of 1.58 (95% confidence-interval (CI) 1.10-2.26) for fluoride exposure. With further adjustment for the percentage of farming population in the maternal county of residence, a variable highly correlated with fluoride exposure, the adjusted odds ratio was 1.15 (95% CI 0.79-1.77). These results suggest that further studies are warranted to evaluate the effects of farming and fluoride in drinking water on the occurrence of intracardiac blood flow defects.