Department of Public Health and Infectious Diseases, P.le Aldo Moro 5, 00185, Sapienza University, Rome, Italy.
Sci Total Environ. 2012 Oct 1;435-436:115-23. doi: 10.1016/j.scitotenv.2012.07.004. Epub 2012 Jul 28.
The aims of the study were to evaluate the feasibility of urinary trans, trans-muconic acid (u-t,t-MA) and urinary S-phenylmercapturic acid (u-SPMA) as markers of exposure to urban benzene pollution for biomonitoring studies performed on children and to investigate the impact that creatinine correction may have on the classification of children exposure status. U-t,t-MA, u-SPMA, u-cotinine, and u-creatinine levels were measured in urine samples of 396 Italian children (5-11 years) living in three areas with different degrees of urbanisation (very, fairly and non-urban). The median u-SPMA levels significantly increased with increased urbanisation: non-urban (0.19 μg/L; 0.22 μg/g creatinine)<fairly urban (0.28 μg/L; 0.28 μg/g creatinine)<very urban group (0.92 μg/L; 0.90 μg/g creatinine). Differences in the levels of u-t,t-MA excretion related to the degree of urbanisation were revealed only by multivariate analyses. Neither u-SPMA nor u-t,t-MA levels were influenced by environmental tobacco smoke (ETS) exposure. Athletic activity during the sampling day was negatively associated with u-SPMA in the model built with u-SPMA adjusted for creatinine, but not in the model where unadjusted u-SPMA was used. This finding demonstrates that u-creatinine correction may alter the results when an independent variable is unrelated to the chemical concentration itself but is related to the u-creatinine levels. These results suggest that both u-SPMA and u-t,t-MA are indicative for assessing environmental benzene exposure in children (exposed and unexposed to ETS) when urine sample is collected at the end of the day. However, u-SPMA is more reliable because u-t,t-MA, also a metabolite of sorbic acid, is less specific for exposure to low levels of benzene. To avoid the possible confounding effect of creatinine correction, it is better to use u-creatinine as additional independent variable in multiple linear regression analyses for evaluating the independent role of the covariates on the variability of u-t,t-MA and u-SPMA levels.
本研究的目的是评估尿反，反-粘康酸（u-t，t-MA）和尿 S-苯巯基尿酸（u-SPMA）作为儿童生物监测研究中接触城市苯污染的暴露标志物的可行性，并探讨肌酐校正可能对儿童暴露状态分类的影响。在意大利三个城市化程度不同的地区（高度、中度和非城市化）采集了 396 名 5-11 岁儿童的尿液样本，测量了 u-t，t-MA、u-SPMA、u-可替宁和 u-肌酐水平。u-SPMA 水平随城市化程度的增加而显著升高：非城市化地区（0.19μg/L；0.22μg/g 肌酐）<中度城市化地区（0.28μg/L；0.28μg/g 肌酐）<高度城市化地区（0.92μg/L；0.90μg/g 肌酐）。只有通过多变量分析才能揭示与城市化程度相关的 u-t，t-MA 排泄水平的差异。u-SPMA 和 u-t，t-MA 水平均不受环境烟草烟雾（ETS）暴露的影响。在调整肌酐后的 u-SPMA 模型中，运动当天的体育活动与 u-SPMA 呈负相关，但在未调整 u-SPMA 的模型中则无此关联。这一发现表明，当自变量与化学浓度本身无关，但与 u-肌酐水平相关时，u-肌酐校正可能会改变结果。这些结果表明，当在一天结束时采集尿液样本时，u-SPMA 和 u-t，t-MA 都可以用于评估儿童（暴露和未暴露于 ETS）的环境苯暴露。然而，u-SPMA 更可靠，因为也是山梨酸代谢物的 u-t，t-MA 对低水平苯暴露的特异性较低。为避免肌酐校正可能产生的混杂影响，最好在多元线性回归分析中使用 u-肌酐作为附加独立变量，以评估协变量对 u-t，t-MA 和 u-SPMA 水平的变异性的独立作用。
