Mutagenic effects of cutting fluids and components in the Salmonella typhimurium mutagenicity assay

Abstract

Emulsions of water-soluble cutting fluids (wsCF) are used in large quantities in the metal industry. In order to reduce the costs for use and disposal of these fluids, new technologies are being introduced. Minimist Lubricant Supply (MLS) uses only minimal amounts of cutting fluids. In contrast to conventional wsCF, which are complex multicompound mixtures, MLS cutting fluids are composed of one or two components only, like fatty alcohols and fatty acid esters. The aim of the study was to identify and compare the mutagenic potential of these cutting fluids as a first indicator of a possible hazard of systemic effects after inhalation or dermal absorption of the fluids at the workplace. The Salmonella typhimurium assay (Ames assay) was used as a screening method to detect mutagenic effects of cutting fluids. Conventional wsCF and MLS cutting fluids were tested in the strains TA 98, TA 100, TA 102 and TA 104, in the presence and absence of an external metabolizing enzyme system (rat liver S9-mix), using a preincubation (20 min) test protocol. For MLS fluids, no mutagenicity was found in a concentration range between 1 and 10 mg/plate in the Ames assay. Among five tested conventional wsCF, two were mutagenic in the Ames assay at concentration ranges between 2.5 and 15 mg/plate. In cooperation with the manufacturer, 18 defined components of cutting fluids were tested separately. The results revealed that formaldehyde generators, derivatives of oxazolidine and hexahydrotriazine used as biocides for preservation of the fluids, were mutagenic. Four components were nonmutagenic but cytotoxic, whereas the remaining components displayed no bacterial mutagenicity. The present results show the potential hazard of biocides for workers handling these fluids. An exposure via inhalation and/or dermal absorption could cause an additional risk due to mutagenic ingredients. Under aspects of workers’ safety, a further discussion about the use of specific components in cutting fluids is recommended.