Il monitoraggio biologico dell'esposizione a benzene: Significato del dosaggio dell'acido t,t-muconico urinario in una popolazione di lavoratori esposti a bassi livelli ambientali di benzene

Trans, trans-muconic acid in the urine has been considered for many years a valid biomarker of occupational exposure to benzene. Our study covered a population of workers exposed to low occupational levels of benzene. Biological monitoring has been performed on 371 males working in 4 different divisions of an oil refining plant. We measured urinary concentrations of t,t-muconic acid at the beginning and at the end of the work shift. Since it is not allowed to smoke during work shift, the biological results would have not been significantly influenced by this habit. The mean urinary excretion of t,t-muconic acid, both at the beginning (76,32 μg/g creat) and at the end of the work shift (112,52 μg/g creat.) were similar to the one measured in non-exposed population. These data confirms the effectiveness of preventive measures adopted in order to minimize the occupational exposure of workers employed in different oil refining processes. However, it is important to point out that, in every different divisions examined, the mean urinary concentrations of t,t-muconic acid at the end of the work shift resulted significantly higher than at the beginning of the shift. This observation could be due to the effective exposure to benzene, even at low concentration, in the workplace. In conclusion our data suggest that, even in the case of a low professional exposure to benzene, the urinary t,t-muconic acid is a very sensitive marker able to show minimal occupational exposure.