Exposure to Benzene among Workers in a Petroleum Transport Company: I. FIGÀ-TALAMANCA, et al. Dip.to Biologia Animale e dell''Uomo, Università di Roma “La Sapienza”—The paper reports on the environmental and biological monitoring of a group of 25 male petroleum transport workers. Environmental benzene exposure was monitored through personal sampling devices during one eight hour shift. Biological monitoring involved measurement of benzene and its metabolite trans, trans muconic acid in the urine at the beginning and at the end of the shift on a Monday and again on a Friday. The mean air concentration of benzene detected in the breathing zone of workers exceeded the threshold limit values (TLV) of the American Conference of Governmental Industrial Hygienist (ACGIH) (TLV=1.6 mg/m3) for workers supervising the loading operations of autocisterns. The values observed among the drivers of multiple autocisterns were just below the TLV, whereas those of the drivers of single cisterns were definitely below the TLV. The biological monitoring revealed that the excretion of benzene increases as exposure increases during the work shift, and reaches the highest concentrations at the end of the work week. The excessive exposure of loading supervisors and drivers of multiple cisterns was also confirmed by the findings of the biological monitoring. (J Occup Health 2001; 43: 53-55)