Nitrosamine in leather dust extracts.

The interest in the carcinogenic and biological actions of N-nitroso compounds arose following the reports of the hepatotoxicity by Freund' and Barnes and Magee2 and ofcarcinogenicity (Magee and Barnes)3 of the simplest nitrosamine: N-nitrosodimethylamine (dimethylnitrosamine) and the subsequent observation of Schoental4 and Druckrey et aP on the carcinogenic action of the nitrosamides: n-methyl N-nitrosourethane and N-methyl N-nitrosurea. Magee and Barnes in 1956 showed the carcinogenic effects of N-nitrosodimethylamine (NDMA) in rats. Evidence that certain consumer and industrial products contain N-nitroso compounds led to speculation that workers in the industries that either use or manufacture nitrosamine precursors (amines and nitrogen oxides) may be exposed to these agents.' One such industry is leather tanning. Dimethylamine sulphate (DMAS, a precursor of N-nitrosodimeth-ylamine NDMA) is used in leather tanneries as a depilatory agent in the hide process (P Walker et al, MITRE Corporation report MTR 7152, 1976). Following these observations, Rounbehler et al carried out a study of human exposure to N-nitrosamine by examining work environments of the leather tanneries.9 Different amounts of NDMA were detected in air samples taken from different sites in the tannery. The highest levels, up to 47 pg/m3 were in the retanning, colouring, and fat liquoring area. Fridman et al detected a nitrosamine group attached to various other groups in different samples by using infrared spectroscopy; nitrosamines show an intense band in the infrared region caused by the vibration of the N = 0 bond.'0 Materials and methods Workers in the leather industry may be exposed to leather dust produced in various tanning operations. Chemical dust is produced during the loading of hide processing drums; leather dust impregnated with chemicals is produced during some mechanical operations including shaving, splitting, and buffing. Samples of leather dust in the form of sweepings Accepted 7 September 1987 were collected from different sites in the tannery and extracts were prepared in different organic solvents such as petroleum, ether, methanol, and acetone using a Soxhlet extraction apparatus. These extracts were purified by using chromatographic techniques including: (a) thin layer chromatography, (b) column chromatography, and (c) preparative thin layer chromatography. The extracts of purified leather dust obtained in the form of different elutes resulting from preparative thin layer chromatography were subjected to infrared spectrophotometers, double beam type,