Indicatori biologici nella valutazione dell’esposizione a bassi livelli di benzene: esperienza in una raffineria

The aim of this study was to assess benzene exposure in a refinery through techniques of environmental and biological monitoring dosing airborne benzene, urinary benzene (BU), t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA). It was also evaluated the influence of genetic polymorphisms on biomarkers of exposure. The study involved 146 exposed subjects and 25 controls. Benzene exposure was measured using a diffusive sampler Radiello®; the analysis was performed by GC-FID. UB, S-PMA and t,t-MA were determined respectively by HS-GC/MS, HPLC-MS/MS and HPLC-UV. The GSTT1 and GSTM1 polymorphisms were detected on mouth mucosa cells by “polymerase chain reaction”-based methods. The personal exposure to benzene was very low (mean 0.033 mg/m3, range <0.002-0.529 mg/m3) but significantly higher (p <0.05) than in the control group (mean 0.012 mg/m3, range <0.002-0.016 mg/m3). Low exposure was also confirmed by the levels of biomarkers (BU: mean 0.57 μg/l, range 0.01-4.79 µg/l; t,t-MA: mean 80.2 µg/g creatinine, range <3.0-946.2 µg/g creatinine; S-PMA: mean 4.15 µg/g creatinine range <0.1-80.1 µg/g creatinine). The analysis of GSTT1 genotype associated with post-shift urinary excretion of S-PMA showed that the efficiency of biotransformation of benzene in the S-PMA is lower in subjects with GSTT1 null allele compared with non-null (p <0.05).