Inhalation exposure in Drosophila mutagenesis assays: experiments with aliphatic halogenated hydrocarbons, with emphasis on the genetic activity profile of 1,2-dichloroethane.

A series of mutation experiments was carried out with Drosophila melanogaster using inhalation exposure. 1,2-Dichloroethane (DCE) and 1,2-dibromoethane (DBE) were active in the sex-linked recessive lethal assay (SLRLT), whereas dichloromethane, dibromomethane, 1,2-dichloropropane and 1,3-dichloropropane were not. Compared to DBE, DCE is a less potent mutagen in the SLRL system. For both compounds, there is no evidence of a clear-cut dose-rate effect. DCE and dichloromethane were also investigated in the somatic mutation and recombination test (SMART), with results similar to those from the SLRLT. For DCE the genetic activity profile was further analyzed by carrying out a sex-chromosome loss assay and a complementation analysis of a series of induced recessive lethal mutations. A review of the use of inhalation in mutagenicity assays with Drosophila shows that this route of exposure is an effective one. Especially with chronic exposure times, rather low exposure concentrations can be detected. With compounds of intermediate volatility inhalation is not superior to other modes of administration; nor is it likely to be sensitive enough for in situ monitoring.