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

Area of Science:

• Occupational Health
• Toxicology
• Analytical Chemistry

Background:

• Benzidine and its conjugates in urine are biomarkers for occupational exposure to benzidine-based azo dyes.
• Assessing exposure levels is crucial for worker safety in industries utilizing these dyes.

Purpose of the Study:

• To investigate the presence of benzidine and its conjugates in the urine of workers exposed to benzidine-derived dyes.
• To evaluate the effectiveness of urinary analysis in monitoring occupational exposure.

Main Methods:

• Urine samples were collected from 29 workers across textile dyehouses, tanneries, and quality control laboratories.
• Gas chromatography/mass spectrometry (GC/MS) was employed for the analysis of 200 urine samples over 15 months.
• Strong acid hydrolysis was performed on specific samples to detect conjugated metabolites.

Main Results:

• No free benzidine or monoacetylbenzidine was detected in any of the 200 analyzed samples.
• Trace amounts of benzidine were detected after acid hydrolysis in urine samples from textile dye weighers with suboptimal hygiene.
• This suggests the excretion of benzidine-derived dyes or their metabolites in specific occupational settings.

Conclusions:

• Standard urinary analysis for free benzidine may underestimate occupational exposure to benzidine-based azo dyes.
• Hydrolysis is essential to detect conjugated metabolites, providing a more comprehensive assessment of exposure.
• Workplace hygiene standards significantly impact the potential for exposure and subsequent metabolite excretion.