Dry etching processes in semiconductor manufacturing use ionized gases in closed reactors at pressures below 1 torr. Vacuum pump systems that service the reaction chambers are potential sources of exposure to complex mixtures of inorganic and organic compounds. These mixtures consist of unused process gases and process by-products that condense and accumulate in the vacuum pump oils. To evaluate potential hazards of dry etch vacuum equipment, a contaminated vacuum pump oil sample from a BCl3/Cl2 etching process was analyzed. The waste oil was administered by gavage for 14 or 28 days to male and female Wistar rats. Neither death nor behavioral changes occurred after subchronic treatment or during a 14-day posttreatment period. Only slight effects on body weights, clinical chemistry, and hematology data were seen in the exposed animals, although the livers of all waste oil-exposed rats of both sexes showed remarkable hypertrophic degenerations. Genotoxicological investigations were performed through the Ames assay (Salmonella assay) and the Micronucleus assay. The contaminated oil sample caused clear genotoxic effects in both test systems.