Biologicalmonitoring of low-level exposure to benzene

Department of Public Health, Clinical and Molecular Medicine, Occupational Health Section, University of Cagliari, Asse Didattico della Facoltà di Medicina, Monserrato, Cagliari, Italy.
La Medicina del lavoro (Impact Factor: 0.55). 09/2012; 103(5):338-46.
Source: PubMed


Conflicting opinions exist about the reliability of 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-PAMA) and urinary benzene (U-Benz) to detect low level occupational and environmental exposure to benzene.
We monitored airborne benzene by personal air sampling, and U-Benz, s-PMAI, 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. Information on personal characteristics, diet and events during the sampling day was acquired through in person interviews.
The median concentration of airborne benzene was 25.2 microg/m3 in oil refinery workers, and 8.5 microg/m3 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, while no correlation was seen with t,t-MA and s-PMA readings in either samplings. The two benzene metabolites were frequently below limit of detection (LOD), particularly among the general population study subjects (17-9% and 39%, for t,t-MA and s-PMA respectively). Morning U-Cotinine excretion showed a good correlation with U-Benz in the morning and in the evening sampling (p < 0.001), and with s-PMA in the evening sample (p < 0.001), but not with 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 < 0.05). The multiple regression analysis adjusting by BMI and number of cigarettes smoked during the day confirmed the results of the univariate analysis.
Our results suggest that unmetabolized U-Benz would allow a more reliable biomonitoring of low-level exposure to benzene than s-PMA and t,t-MA.

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Available from: Silvia Fustinoni, May 17, 2014
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    • "Within a multicentre Italian project on biomonitoring exposure to polycyclic aromatic hydrocarbons (PAH) and benzene, in 2006–2007, 182 randomly selected subjects agreed to participate within the metropolitan area of Cagliari , the major urban area in the island of Sardinia, Italy. Smoking is by far the greater contributor to benzene intake among non-occupationally exposed subjects (Fustinoni et al. 2005; Campagna et al. 2012; Hoet et al. 2009); therefore, in order to be able to highlight other potentially contributing environmental factors, we excluded 96 current smokers and extracted data on 86 non-smoking, nonoccupationally exposed subjects, 48 males and 38 females, for the purposes of the present study. All persons gave their informed consent prior to their inclusion in the study. "
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    ABSTRACT: Analytical difficulties and lack of a biological exposure index and reference values have prevented using unmetabolized urinary benzene (UB) excretion as a biomarker of low-level environmental exposure. To explore what environmental factors beyond active smoking may contribute to environmental exposure to benzene, we monitored UB excretion in a non-smoking, non-occupationally exposed sample of the general population. Two spot urine samples were obtained from 86 non-smoking, non-occupationally exposed subjects, selected among a random sample of the general population of the metropolitan area of Cagliari (Sardinia, Italy), at 8:00 a.m. (UBm) and 8:00 p.m. (UBe). UB was measured by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry analysis. Questionnaire information on personal and environmental exposures during the sampling day was gathered with personal interviews. Multivariate analysis of variance and multiple regression model were applied to investigate the role of such variables on the level of UB. The ninety-fifth percentile of UBe in this population was 311.5 ng/L, which is tentatively proposed as the UB guidance value for unexposed populations. UBm and urban residence were the only predictors of a significant increase in UBe excretion. Self-reported residential vehicular traffic will not account for the excess median value among urban residents; commuting time among urban residents showed a suggestive nonsignificant linear correlation with UBe, but the small sample size prevented reliable inference to be drawn. Age, environmental tobacco smoking, employment status and body mass index did not affect UB excretion. Our findings support the use of unmetabolized UB as a specific and sensitive biomarker of low-level environmental exposure to benzene.
    International Archives of Occupational and Environmental Health 12/2013; 87(7). DOI:10.1007/s00420-013-0925-2 · 2.20 Impact Factor
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    La Medicina del lavoro 10/2012; 103(5):413-6. · 0.55 Impact Factor
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    ABSTRACT: 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.
    Giornale italiano di medicina del lavoro ed ergonomia 10/2013; 35(4):251-5.