Benzene is a human carcinogen and an ubiquitous environmental pollutant. Identification of specific and sensitive biological markers is critical for the definition of exposure to low benzene level and the evaluation of the health risk posed by this exposure. This investigation compared urinary trans,trans-muconic acid (t,t-MA), Sphenylmercapturic acid, and benzene (U-benzene) as biomarkers to assess benzene exposure and evaluated the influence of smoking and the genetic polymorphisms CYP2E1 (RsaI and DraI) and NADPH quinone oxidoreductase-1 on these indices. Gas station attendants, urban policemen, bus drivers, and two groups of controls were studied (415 subjects). Median benzene exposure was 61, 22, 21, 9 and 6 Mg/m 3 , respectively, with higher levels in workers than in controls. U-benzene, but not t,t-MA and S-phenylmercapturic acid, showed an exposure-related increase. All the biomarkers were strongly influenced by cigarette smoking, with values up to 8-fold higher in smokers compared with nonsmokers. Significant correlations of the biomarkers with each other and with urinary cotinine were found. A possible influence of genetic polymorphism of CYP2E1 (RsaI and/or DraI) on t,t-MA

Healthconditions were evaluated in 80electrical workers exposed for many years to polychlorinated biphenyl (PCB) mixtures with a 42% mean chlorine content, who had blood PCB concentrations from 41 to 1319 pg/kg. The clinical study was based on personal history data, physical examination, and laboratory tests (red cell and leukocyte count; determination of haemoglobin, packed cell volume, bilirubin, serum protein electrophoretic fractions, pseudocholinesterase, AST, ALT, GGT, and OCT). Fifteen workers were found to have skin diseases-chloracne (4), folliculitis (4), oil dermatitis (1), juvenile acne (1), and dermatitis due to irritative or allergic agents (5). Sixteen workers showed more or less pronounced hepatic involvement, consisting most often of hepatomegaly with an increase in serum GGT, AST, ALT, and OCT values. In two workers bleeding cavernous haemangiomas were discovered, in one case associated with chronic myelocytic leukaemia. All the workers with chloracne were employed on electric capacitor impregnation with PCBs, and no definite association was found between chloracne and blood PCB concentrations. Conversely, a significant positive association was found between the abnormal liver findings and blood PCB concentrations, particularly trichlorobiphenyl blood concentrations.The abnormal hepatic findings observed are similar to those reported in experimental animals given PCBs, and in some workers such findings should probably be considered as clinical signs of hepatic microsomal enzyme induction.The toxicity of polychlorinated biphenyls (PCBs) has been studied in several animal species: high oral doses of PCBs induce liver damage in non-human primates and in rodents.1-4 In monkeys, depending on dose and mode of administration, acne, alopaecia, hyperpigmentation of the skin, thymic atrophy, ocular lesions, and subcutaneous oedema have been also observed.5-7 In rodents, however, low doses of PCBs, not sufficient to cause macroscopically evident organic disease, can alter several biochemical functions: after chronic oral or parenteral PCB administration it was possible to show an increase in the smooth endoplasmic reticulum of liver cells with induction of microsomal enzyme activity,8-'0 hepatic porphyria, Requests for reprints to:

The comparative evaluation of TOL-B and TOL-U showed that they can be considered to be equivalent biomarkers as regards their capacity to distinguish workers and controls and to correlate with exposure. However, considering that TOL-U does not require an invasive specimen collection, it appears to be a more convenient tool for the biological monitoring of exposure to toluene.

No abstract