129 Urinary benzene as a biomarkers of low-level exposure to benzene

We compared the ability of the urinary excretion of trans,trans -muconic acid ( t,t -MA), s -phenilmercapturic acid ( s -PMA) and urinary benzene (U-Benz) to detect low level occupational and environmental exposure to benzene. Methods We monitored airborne benzene by personal air sampling, and U-Benz, s -PMA, t,t -MA and cotinine (U-Cotinine) in spot urine samples, collected at 8 am and 8 pm, in 32 oil refinery workers and 65 subjects, randomly selected among the general population of urban and suburban Cagliari, Italy. Results The median concentration of airborne benzene was 25.2 µg/m 3 in oil refinery workers, and 8.5 µg/m 3 in the general population subgroup. U-Benz in morning and evening samples was significantly more elevated among oil refinery workers than the general population subgroup ( p = 0.012, and p = 7.4 x 10 -7 , respectively) and among current smokers compared to non-smokers ( p = 5.2 x 10 -8 , and p = 5.2 x 10 -5 respectively). Benzene biomarkers and their readings in the two sampling phases were well correlated to each other. The Spearman’s correlation coefficient with airborne benzene was significant for U-Benz in the evening sample, but not for t,t- MA and s -PMA in either sampling. Morning U-Cotinine excretion showed a good correlation with U-Benz in the morning and in the evening sampling ( p s -PMA in the evening sample ( p t,t- MA in either samplings. t,t- MA in the evening sample was the only biomarker showing a moderate inverse correlation with BMI (p Discussion Our results suggest that unmetabolised U-Benz would allow a more reliable biomonitoring of low-level exposure to benzene than s -PMA and t,t- MA.