Determining the lethal concentration of toluene on Drosophila melanogaster and the resulting morphological effects of toluene exposure on fly offspring

Toluene is a volatile organic compound found in crude oil, paint, and as a by-product of petroleum refining.  According to the Environmental Protection Agency and Office of Environmental Health Hazard Assessment, toluene causes irregular fetal development along with neurological and hepatic defects in humans.  To study the effects of toluene on fruit flies, we developed a continuous-flow system that delivers and exposes known concentrations of toluene vapor to test populations of Drosophila melanogaster.  We determined the lethal concentration that kills 50% of the test population (LC₅₀) to be between 148 and 310 ppm.  To study effects of toluene on fly offspring, surviving toluene-exposed females were mated with unexposed males.  Larval offspring were collected at day 4 and, using light and scanning electron microscopy, morphological changes in larvae from both exposed and unexposed females were examined.  Developmental changes were compared to known mutagenic effects on the fly’s embryonic and physiological development.