Presence of N-nitrosodiethanolamine contamination in Canadian metal-working fluids

N-Nitroso compounds are notorious mutagens, carcinogens and teratogens that can be seriously hazardous to human health. Metal-working fluids (MWFs) are used for lubricating and cooling the cutting and grinding surfaces of metal-working machines. Because a limited survey is available on MWFs used in Canada, this study was performed to assess the magnitude of the presence of N-nitroso compounds in these MWFs. N-nitrosodiethanolamine (NDELA) was found to be the major contaminant in different brands of MWFs. In the case of soluble oils, the concentrations of NDELA vary between 0.02 and 7.53 ppm, but it was absent in insoluble oils. The concentrations of nitrate in soluble oils vary between 1.6 and 67.0 ppm and in insoluble oils between 0.35 and 1.5 ppm. Nitrite was detected only in one sample of soluble oil (4.2 ppm) whereas it was absent in insoluble oils. By comparing the studies reported by two different Canadian groups in 1978 and 1990, concentrations of NDELA in the MWFs used in Canada were significantly reduced after a period of 12 years. The present study shows an additional significant decline in the concentrations of NDELA in MWFs.