Ong C N, Kok P W, Ong H Y, Shi C Y, Lee B L, Phoon W H, Tan K T
Department of Community Medicine, National University of Singapore.
Occup Environ Med. 1996 May;53(5):328-33. doi: 10.1136/oem.53.5.328.
To carry out a comprehensive field investigation to evaluate various conventional and recently developed biomarkers for exposure to low concentrations of benzene.
Analyses were carried out on environmental air, unmetabolised benzene in blood and urine, urinary trans, transmuconic acid, and three major phenolic metabolites of benzene: phenol, catechol, and hydroquinone. Validations of these biomarkers were performed on 131 never smokers occupationally exposed to the time weighed average benzene concentration of 0.25 ppm (range, 0.01 to 3.5 ppm).
Among the six biomarkers studied, unmetabolised benzene in urine correlated best with environmental benzene concentration (correlation coefficient, r = 0.76), followed by benzene in blood (r = 0.64). When urinary metabolites were compared with environmental benzene, trans, trans-muconic acid showed a close correlation (r = 0.53) followed by hydroquinone (r = 0.44), and to a lesser extent with urinary phenol (r = 0.38). No correlation was found between catechol and environmental benzene concentrations. Although unmetabolised benzene in urine correlates best with benzene exposure, owing to serious technical drawbacks, its use is limited. Among the metabolites, trans, trans-muconic acid seems to be more reliable than other phenolic compounds. Nevertheless, detailed analyses failed to show that it is specific for monitoring benzene exposures below 0.25 ppm.
The overall results suggest that most of the currently available biomarkers are unable to provide sufficient specificity for monitoring of low concentrations of benzene exposure. If a lower occupational exposure limit for benzene is to be considered, the reliability of the biomarker and the technical limitations of measurements have to be carefully validated.
开展一项全面的现场调查，以评估各种传统及近期开发的低浓度苯暴露生物标志物。
对环境空气、血液和尿液中未代谢的苯、尿中转式、反式粘康酸以及苯的三种主要酚类代谢物：苯酚、儿茶酚和对苯二酚进行分析。在131名从未吸烟且职业性接触苯的时间加权平均浓度为0.25 ppm（范围为0.01至3.5 ppm）的人群中对这些生物标志物进行验证。
在所研究的六种生物标志物中，尿中未代谢的苯与环境苯浓度的相关性最佳（相关系数，r = 0.76），其次是血液中的苯（r = 0.64）。当将尿代谢物与环境苯进行比较时，转式、反式粘康酸显示出密切相关性（r = 0.53），其次是对苯二酚（r = 0.44），尿中苯酚的相关性较小（r = 0.38）。未发现儿茶酚与环境苯浓度之间存在相关性。尽管尿中未代谢的苯与苯暴露的相关性最佳，但由于严重的技术缺陷，其应用受到限制。在代谢物中，转式、反式粘康酸似乎比其他酚类化合物更可靠。然而，详细分析未能表明它对监测低于0.25 ppm的苯暴露具有特异性。
总体结果表明，目前大多数可用的生物标志物无法为监测低浓度苯暴露提供足够的特异性。如果要考虑更低的苯职业接触限值，则必须仔细验证生物标志物的可靠性和测量的技术局限性。
