N-nitrosoalkanolamines in cosmetics

A method has been developed for the determination of the N-nitrosoalkanolamines, N-nitrosodiethanolamine (NDELA) and N-nitrosobis(2-hydroxypropyl)amine (NDHPA) in cosmetics. In model systems, we studied nitrosation of the most relevant precursors by NaNO2, by the preservatives Bronopol and Bronidox and by nitric oxides. Secondary amines were most rapidly nitrosated, and Bronopol, Bronidox and atmospheric nitric oxides appeared to be the most relevant nitrosating agents. In order to remove the most important sources of contamination, the Federal Health Office issued an official recommendation to producers to avoid use of secondary amines in cosmetics (March, 1987). Analysis of cosmetics taken from the German market 6-18 months later showed that only 19/126 samples were contaminated with NDELA (12-235 micrograms/kg or NDHPA (40-215 micrograms/kg). The results reflect a strong downward trend in contamination.