Biological monitoring in the metal working industry.

N-Nitrosodiethanolamine (NDELA) is a strong carcinogen in animal experiments. Its occurrence in cutting and grinding fluids represents a major risk for workers who come into contact with those compounds. But until now it was not possible to describe the extent of N-nitrosodiethanolamine exposure at the workplace. Since 60-90% of N-nitrosodiethanolamine given by oral, intravenous, epicutaneous or intratracheal application in rat experiments is excreted unchanged in the urine, N-nitrosodiethanolamine should be found in the urine of workers in the metal working industry. Analyses of grinding fluids containing di- and triethanolamine in combination with up to 30% nitrite showed concentrations of up to 593 mg/kg N-nitrosodiethanolamine in the original, concentrated fluid and up to 90 mg/kg in ready-to-use emulsions. In preliminary investigations, it was also found in the urines of metal grinders: of 264 urines analysed, 166 showed positive results (greater than 0.5 micrograms/kg) with levels up to 103 micrograms/kg N-nitrosodiethanolamine. These results indicate that workers' exposure to NDELA can be monitored by urine analysis.