Abstract
The purpose of this research is to determine how short-term tests can be used as a first screen to evaluate the potential interaction between damage induced by radiation and chemicals present in the work environment. There is a potential for exposure of workers to both radiation and chemicals. Exposure standards are set one compound at a time. Little consideration is given to potential additive, antagonistic, or synergistic interactions caused by combined exposures to physical and chemical agents. Short-term tests can help identify areas of concern. We are reporting on the types of interactions observed between radiation-induced cytogenetic damage in vitro with that induced by metals, fibers, and organic solvents present in the nuclear industry and at nuclear waste sites. Synergistic interactions were observed for the induction of chromatid deletions and chromatid exchanges by combined exposure to beryllium and X rays. These aberrations are produced by radiation only during the S/G2 stages of the cell cycle. This suggests that the synergistic interactions occur only in cells that are in these stages of the cell cycle at the time of the exposure. No interactions were observed between chromosome damage induced by gamma rays and the cellular damage induced by silicon carbide whiskers. Silicon carbide whiskers were selected as a representative fiber that has application in space nuclear systems. It produced a concentration-related increase in cell killing in vitro in both epithelial cells and fibroblasts. The frequency of micronuclei induced by silicon carbide whiskers did not increase in either cell type. Using micronuclei as an endpoint, no interactions were observed between damage from ionizing radiation and that produced by the organic solvents. However, the genotoxic responses to the organic solvents methyl isobutyl ketone (hexone) and tributyl phosphate, present in large amounts in nuclear waste sites, were investigated. Both hexone and tributyl phosphate produced a concentration-related increase in cell killing with no increase in the frequency of micronuclei. Investigating the interactions between radiation and chemicals in producing genotoxic damage can help to define potential problem areas and provide information on areas which require additional research to provide the basis for better worker protection both in the nuclear industry and during nuclear waste site cleanup.
