Exposure to low doses of benzene: biological monitoring exposure in a group of occupational exposed workers and a group of general population. Even if exposure to benzene is considerably decreased in last years, the interest for this cercinogenic agent is still important. Benzene is used as additive in gasoline and it is present in cigarette smoke. Therefore benzene is considered an important toxic agent not only for occupational exposed people, but also for general population, in particular if living in high polluted areas. Aim of the present study is evaluation of trans, trans-muconic acid in urine of workers exposed to benzene and in the general population, making a distinction between subjects living in an urban centre and subjects living in rural areas. Each subject was invited to complete a questionnaire about job, diet, residence, hobbies and tobacco-smoking. Every one was submit to a physical examination, exams as ECG, audiometry, spirometry and laboratory test to investigate about blood count, liver and kidney function. It was used as biological exposure index the urinary trans, trans-muconic acid (t,t-MA).
Results: t,t-MA was increased in smokers compared to nonsmokers, in exposed workers (t,t-MA = 0.09 mg/L, DS 0.22) compared to general population (t,t-MA = 0.08 mg/L, DS 0.21) and in people living in urban zone compared to people living in rural areas. In particular, among occupational exposed subjects, we found concentration of urinary t,t-MA greater in the subjects living in urban zone (t,t-MA = 0.10 mg/L, DS 0.23) in comparison with the subjects living in rural areas (t,t-MA = 0.09 mg/L, DS 0.3). The same result we found in general population divided in two groups, people living in urban zone (t,t-MA = 0.09 mg/L, DS 0.21) and people living in rural areas (t,t-MA = 0.07 mg/L, DS 0.21). We have to observe that the results obtained have not a statistical relevance and the concentrations of t,t-MA in urines is always less than biologic limits. Anyway, in consideration of the carcinogenic properties of benzene and of its dose-response relation, without a treshold dose, we believe that the environmental and occupational monitoring is very important.