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We investigated the presence of DNA damage and telomerase activity levels in exfoliated urothelial cells of rubber workers employed in tyres production, formerly exposed to potentially carcinogenic aromatic amines (phenyl-2-naphthylamine), PAHs and other chemicals. The aim was to identify sensitive biomarkers of early carcinogenic effect at target organ, to use in biomonitoring studies of workers at risk for previous occupational exposure to potential carcinogens.
Methods
We used comet assay and quantitative telomerase repeat amplification protocol (TRAP) assay in 159 workers (mean age 60 ±12 years) and 96 unexposed subjects (mean age 57 ±12 years). On the basis of working information (tasks and seniority in specific work stage) we identified five classes of risk for previous exposure to amines and other potentially carcinogenic chemicals. On the same samples standard urine cytology (Papanicolau staining test) for the assessment of markers indicative of bladder cancer was also performed.
Results
For comet assay tail moment (Tm) indicative of DNA damage was evaluated and subjects with mean values higher than cut off normal value (Tm=30) were considered positive. DNA damage was present in 10% of ex-exposed workers in respect to 2% of controls. TRAP analysis showed results ranging form 5 to 123 AEU (Arbitrary Enzymatic Units), with median values of 38 AEU in ex-exposed and 34 AEU in controls. Considering TRAP values ? 50 AEU, concordant comet and TRAP results were observed in 139/159 (87,4%) ex-exposed with positivity in 11 workers all belonging to the classes (4 and 5) at higher risk for previous exposure to carcinogens. Cytological analysis showed in 6 of such cases a phlogosis condition.
Discussion
The findings show that the analysis of these bio-molecular markers in urine cells could be potentially more accurate than conventional cytology in monitoring workers exposed to mixture of bladder potential carcinogens.