8.6 Genotoxicity and related end-points
There is a limited amount of information available on the genotoxicity of barium compounds. No in vivo studies have been conducted. Most in vitro studies have found that barium chloride and barium nitrate did not induce gene mutations in bacterial assays with or with out metabolic activation. Ames assays with Salmonella typhimurium strains TA1535, TA1537, TA1538, TA97, TA98, and TA100 with or without metabolic activation (Monaco et al., 1990, 1991; NTP, 1994), rec assays with Bacillus subtilis strains H17 and H45 (Nishioka, 1975; Kanematsu et al., 1980), and a microscreen assay with Escherichia coli with metabolic activation (Rossman et al., 1991) have produced negative results with barium chloride. Negative results have also been observed for barium nitrate in the rec assay using B. subtilis strains H17 and H45 (Kanematsu et al., 1980). Barium chloride induced gene mutations in L5178Y mouse lymphoma cells with, but not without, metabolic activation (NTP, 1994). Neither barium acetate nor barium chloride decreased the fidelity of DNA synthesis in avian myeloblastosis virus DNA polymerase (Sirover & Loeb, 1976). In mammalian cells, barium chloride did not induce sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells, with or without activation (NTP, 1994). In summary, except for the mouse lymphoma assay, results of in vitro tests have been generally negative.