The hazard associated with nitrosamines in cutting fluids was discussed. A study confirming the presence of diethanolnitrosamine (1116547) (DENA) in samples of commercial cutting fluids produced by four randomly selected companies is summarized. During an actual machining operation, 1000 parts per million (ppm) DENA were found in the cutting fluid before use and 384ppm after use, suggesting exposure of machine operators to the nitrosamine. An epidemiologic study reported a slight, nonsignificant excess of mortality from respiratory tract and digestive system cancers among male workers exposed to cutting fluids in metal machine jobs. The four categories of commercial cutting fluids were presented. NIOSH estimated that 780,000 persons were occupationally exposed during manufacture and use of cutting fluids. Recommendations for reducing dermal and respiratory exposure to cutting fluids are given. These include using local exhaust ventilation, substitution with a cutting fluid that does not contain nitrosamines or the ingredients for nitrosamine formation where feasible, using chemically impervious clothing and barrier creams, and cleansing any area that becomes wet with cutting fluids. It is noted that NIOSH is planning industrial hygiene and epidemiologic studies of nitrosamine exposure and carcinogenesis bioassays.