Pesticides and fertilizers, as used in modern agriculture, contribute to the overall low-level contamination of groundwater sources. In order to determine the potential of pesticide and fertilizer mixtures to produce developmental toxicity at concentrations up to l00 times those found in groundwater, we studied a mixture of five pesticides (aldicarb, atrazine, dibromochloropropane, ethylene dibromide, and simazine) and one fertilizer component (ammonium nitrate).
These chemicals and their relative concentrations in the stock mixture were selected on the basis of survey data from California (pesticides) and Iowa (fertilizer). The mixture CALF was administered in the drinking water to Sprague-Dawley rats (21-23 per group) on gestational days 6 to 20 at three dose levels, i.e., lX, l0X, and l00X, where lX was the median concentration of each pesticide component as determined in the surveys. Dams were monitored daily for signs of toxicity. On gd 20 fetuses were removed and examined for effects of CALF on growth, viability, and morphological development.
Maternal body weights, food and water consumption and clinical signs were all similar to the control values. No adverse effects of CALF treatment were observed for measures of embryo/fetal toxicity, including resorptions per litter, live litter size, and fetal body weight. CALF did not cause an increased incidence of malformations or variations.
In summary, under the conditions of this study, exposure of pregnant rats to a mixture of ammonium nitrate and pesticides at levels up to l00-fold greater than the median human exposure in groundwater supplies did not show any detectable adverse effects on the dam or developing conceptus.