Neurobehavioral development of rats exposed to toluene through maternal milk

ABSTRACT

Organic solvents have been detected in the milk of workers in the rubber industry exposed during gestation to a mixture of solvents at average concentrations lower than the currently accepted occupational limit of exposure (100ppm). The objective of the present study was to determine if exposure of rat offspring to toluene during laction, through maternal milk, would affect the developing brain. There month old, lactating Wistar rats were injedted with toluene (1.2 g/Kg, sc, N = 10) daily from laction day 2(day of delivery - day 1) to day 21. Controls (N=9) were injected with the vehicle (c0rn oil). Offspring (7 pups per litter) were evaluated form neurosomatic development and exploratory behavior before weaning and behavior in the open field. A second group of toluene treated ratas (N=6) and controls (N=6) was used to evaluate behavior of the offspring in the open-field on day 35 and performance in a shuttle box in adulthood. Toluene levels in blood and milk after a single 1.2 g/Kg sc injection were studied in a third group of rats on laction day 10. Toluene levels in milk 4 h after a single injection (10.3ñ6.2) were 5 times higher than in blood (2.1ñ0.8). No effects of treatment on offspring development or on any of the behavioral tests were observed. Sex differences were observed in open-field behavior and performance in the shuttle box. The present results suggest that exposure of pups to high concentrations of toluene through maternal milk does not result in blood levels high enough to affect growth or development