[Monitoring of the occupational and environmental exposure to low doses of benzene]

To verify which of the various biomarkers of internal dose of benzene can be considered reliable for biological monitoring of exposure to the low concentrations present nowadays in working and living environments.The specific literature was analyzed to assess the reliability of the different biomarkers of internal dose.T,t-muconic acid is a non specific biomarker for benzene, valid for exposure to concentrations up to one order of magnitude less than the threshold limit of 3250 microg/m3. S-phenylmercapturic acid (SPMA) is a reliable marker even for exposure to concentrations up to two orders below the threshold value of 3250 microg/m3, and can be considered the biomarker of choice for biological monitoring of workers exposed to benzene. Urinary benzene does not seem to have any real advantages over SPMA for monitoring occupational exposure to benzene, but it does seem to be more reliable than SPMA to assess exposure to concentrations like those present in living environments. A smoking habit influences the urinary excretion of all the described biomarkers, and for the current low levels of occupational and environmental exposure to benzene, must be taken into account when interpreting the results of biological monitoring.