Search for benzidine and its metabolites in urine of workers weighing benzidine-derived dyes

Urinary benzidine and conjugates have been used to assess the extent of occupational exposure to benzidine-based azo dyes. The aim of the present study was to investigate the presence of benzidine and its conjugates in the urine of workers exposed to benzidine-derived dyes. Urine samples were collected from 29 workers in three textile dyehouses, two tanneries, and two dyestuff quality control laboratories in West Yorkshire and Lancashire. In 200 samples, obtained over a period of 15 months and analysed by gas chromatography/mass spectrometry, no free benzidine or monoacetylbenzidine was detected. Nevertheless, after strong acid hydrolysis of urine samples taken on two separate occasions from textile dye weighers where the standard of hygiene appeared below average, trace amounts of benzidine were detected suggesting the excretion of a benzidine derived dye or a metabolite thereof.