Association of transposition of the great arteries in infants with maternal exposures to herbicides and rodenticides

The Baltimore-Washington Infant Study, a case-control study of congenital h eart defects in liveborn infants conducted in 1981-1989, interviewed parent s about a wide range of environmental exposures that occurred during and be fore the pregnancy. In the period 1987-1989, the questionnaire was expanded to include a detailed inquiry about exposures to pesticides. An analysis o f these latter data revealed an association of maternal exposure to any pes ticides during the first trimester with transposition of the great arteries in their infants (TGA; n = 66 infants), relative to 771 control infants, w ith an odds ratio of 2.0 (95% confidence interval (CI): 1.2, 3.3). No other heart defects were associated with pesticides. When analyzed by type of pe sticide and adjusted for covariates, there were associations of TGA with ma ternal exposures to herbicides (odds ratio (OR) = 2.8; 95% CI: 1.3, 7.2) an d to rodenticidal chemicals (OR = 4.7; 95% CI: 1.4, 12.1) but not to insect icides (OR = 1.5, 95% CI: 0.9, 2.6). No data were collected on specific che micals or brand names. These results raise new questions about the possible epidemiologic association of TGA with some classes of pesticides and warra nt new, carefully targeted investigations.