Urinary excretion of 1-pyrenol in automotive repair workers

Summary The urinary excretion of a pyrene metabolite was evaluated in 65 automotive repair workers whose skin was exposed to used mineral oils, and in 41 controls. Pyrene contents were determined in oily material taken from cloths used to clean various types of engines (n = 8) and were found to vary (mean ± SD) from 2.8 ± 0.4 ppm for dirty matter obtained from diesel truck engines to 9.3 ± 8.2 ppm for that from petrol car engines. Tobacco smoking and polycyclic aromatic hydrocarbon (PAH)-rich diets were considered as confounding factors. At both the beginning and the end of the working week, the values of urinary 1-pyrenol were slightly higher in exposed subjects (0.178 ± 0.150 and 0.194 ± 0.135 mol/mol creatinine on Monday and Friday, respectively) than in controls (0.124 ± 0.090 mol/mol creatinine) (Mann-Whitney test, z = 2.741, P < 0.01). The urinary 1-pyrenol values were higher in both smoking and non-smoking subjects than in controls. The highest values were found in urinary samples of smokers exposed to used mineral oils (0.259 ±0.201 mol/mol creatinine). In non-smoking workers (n = 40), post-shift 1-pyrenol values were 0.154 ± 0.105 ol/mol creatinine, as against 0.083 ± 0.042 mol/mol creatinine for the 19 non-smoking controls (Mann-Whitney test, z = 2.765, P < 0.01). In automobile repair workers, urinary 1-pyrenol values before the beginning of the weekly workshift did not differ substantially from those measured at the end of the week, not being related to the subjective degree of dirty skin as stated by workers. Multiple regression analysis between urinary metabolite levels and the three independent variables turned out to be statistically significant (r² = 0.295, 0.246; F-test = 14.2, 11.1; P both < 0.01) for Monday and Friday urinary metabolite values and revealed that tobacco smoking had a greater influence (contribution to r² = 16.1% and 18.3% on Monday and Friday, respectively) than occupational exposure (3.8% and 6.6%, respectively) on urinary levels of 1-pyrenol; the influence of PAH-rich foods on urinary pyrene metabolite levels was only detectable when subjects returned to work after the weekend (5.5%).Comparison between urinary excretion of 1-pyrenol in this group of workers and that found in professionally exposed subjects indicates that exposure to PAHs through contamination of the skin with used engine oil during automotive repair work is very low.