Research progress in carcinogenicity of metalworking fluids

Metalworking fluids (MWFs) is used in the machinery manufacturing industry in huge quantities and with a large number of exposed workers. MWFs can simply be divided into 2 categories: oil-based and water-based fluids, or by its nature into 4 categories: straight oils, soluble oils, synthetic fluids and semi-synthetic fluids. During machining and grinding operations, MWFs is sprayed directly onto the exposed skin of the operator′s hands or face, or is dispersed into the air of the workplace environment and inhaled by the operator, resulting in occupational health hazards due to mechanical splashing, rotating workpiece forces, atomisation and evaporation, burning or pyrolysis due to increased surface temperature of the metal cutting workpiece. The health hazards of MWFs to skin and respiratory system are well established, but the issue of its carcinogenicity is still debated. In this study, the carcinogenicity of MWFs is reviewed in terms of the relationship between exposure to MWFs and cancer, the relationship between MWFs types and cancer, and the carcinogenic factors of MWFs for providing a reference for further research on the health hazards of MWFs.