New studies on the in vitro genotoxicity of sodium molybdate and their impact on the overall assessment of the genotoxicity of molybdenum substances

Abstract The potential of molybdenumsubstances to cause genotoxiceffects has been studied previously. However, a review of existing in vitro data, including an assessment of relevance and reliability, has shown that inconsistent results have been observed in the past. To resolve the inconsistencies, new studies were performed with the highly soluble sodium molybdatedihydrate according to OECD test guidelines. In a bacterial reverse mutation assay sodium molybdatedihydrate did not induce reverse mutations in five strains of Salmonella typhimurium . No mutagenic or clastogeniceffect was observed at the tk locus of L5178Y mouse lymphoma cells. In a micronucleustest in cultured human peripheral blood lymphocytesno clastogenicor aneugeniceffects were seen. These results can be read across to other inorganic molybdenumsubstances, that all release the molybdateion [MoO 4 ] 2− under physiological conditions as the only toxicologically relevant species. In summary, a weight of evidence assessment of all available in vitro data shows no evidence of genotoxicityof molybdenumsubstances.