Screening toxic effects of volatile organic compounds using Drosophila melanogaster

The suitability of Drosophila melanogaster for biological screening of the toxic effects of volatile organic compounds was investigated. Adult flies were exposed to vapours of some organic solvents and gasoline under saturating conditions in the sublethal range. In some cases the dose-response relationship was studied. As a measure of the overall metabolism, CO2 production was recorded before and after exposure, including the recovery period, and the body activity was scored and classified as "normal behaviour", hyperactivity or excitement or narcosis. Significant differences were observed for the different solvents and volatile mixtures (vapours of acetone, benzene, methanol, toluene, xylene, diethylether, leaded and unleaded gasoline and diesel fuel). The length of the narcosis induced by the volatile organic compounds correlated well with their octanol-water coefficients. After exposure to benzene, toluene and gasoline a marked increase in the CO2 production during narcosis was observed. Methanol exposure led to a long-lasting increase in CO2 production, but did not cause narcosis. There were also differences in the behaviour (body activities) in the recovery phase between the solvents tested. Thus, the results from these experiments suggest that the measurement of CO2 production combined with the scoring of body activities in Drosophila can be used as a sensitive screening procedure in inhalation toxicology, revealing different types of toxic reactions for different types of volatile compounds.