The contribution of occupational exposure vs. cigarette smoking in determining the internal dose of 1,3-butadiene in Italian workers

Aims: The aim of this study was to compare the contribution of occupational exposure and smoking habit in determining the total intake of 1,3-butadiene (BD), a probable carcinogen to humans, in chemical workers. Methods: Forty-two BD healthy male petrochemical workers (W), and forty-three internal controls (C) entered the study. Personal exposure to airborne BD was evaluated as time weighted average value during the work-shift. BD in exhaled air, blood and urine was measured in specimens collected both at the beginning and at the end of the work-shift. Information on cigarette smoking was obtained by questionnaire. Results: Median exposure to BD was 1.5 (ranging from <0.1-201 ) µg/m3 in W, and 0.4 (<0.1-10) µg/m3 in C. BD in exhaled air, blood and urine was about 1.5-3 times higher in W then in C (p<0.05). Correlations between these biomarkers and airborne BD (0.28<Pearson r<0.39) and between the biomarkers themselves (0.78<Pearson r<0.90) were significant. Cigarette smoke had a great impact on internal dose: an increase of BD up to 20 folds was found in biological fluids of smokers compared to non-smokers. Multiple linear regression analysis correlated BD in exhaled air, in blood or in urine with personal exposure and cigarette smoking (0.72R0.77), explaining up to 59% of the observed variability. Conclusion: In the present study airborne BD exposure was very low. Notwithstanding, the levels of BD in exhaled air, blood and urine were positively associated with personal exposure and showed that cigarette smoke, rather then occupational exposure, was the major source of BD exposure in the investigated subjects.