Biomonitoring of benzene exposure by trace analyses of phenylguanine

Summary From preliminary experiments it was known that radiolabelled benzene and some of its metabolites during its metabolic activation process produce different in vitro DNA-phenyladducts in mitoplasts [5, 11].As we reported previously [9] at least one of these adducts, N-7-phenylguanine, is excreted in the urine of rats in measurable amounts, probably through an excision-repair mechanism after an inhalation experiment. Now we found, after i.p. application of benzene in the urine of rats, a compound separated by cation-exchange chromatography that behaves like a synthezised N-7-phenylguanine reference substance with respect to its retention index and the UV-absorption. This finding could be confirmed by HPLC-measurements with reversed-phase carrier materials. Silylation and gaschromatographic/mass spectrometric (GC/MS) separation of the fraction, which contains the phenylguanine, revealed that these fractions contain further phenyl adducts. Furthermore we studied the time-dependent excretion of the DNA-base adduct. Surprisingly the excretion dropped to zero on the fourth day and showed a new increase thereafter.     

佛山市城区室内装修污染特征初探

目的 为了解佛山市室内装修空气污染状况，通过对佛山市室内装修污染物进行调查，掌握室内装修污染的一些基本特征并提出控制措施。方法 根据卫生部《室内空气质量卫生规范》以及《室内空气污染物的检验方法》方案，调查采用了问卷调查和现场检测的方法。结果 佛山市室内装修空气污染物主要为甲醛，苯，总挥发性有机物(TVOC)，超标率分别为86％，36％，23％。结论 目前佛山市城区室内装修污染物的特征为：有机污染较无机污染严重，室内甲醛污染严重，苯次之而氢污染相对较轻，室内空气苯污染车辆、居室高于办公室，甲醛污染居室，办公室高于车辆。     

混合效应模型在研究接触-效应关系中的应用

目的 用混合效应模型研究工人接苯水平与白细胞水平的关系及其影响因素,并确定最适接触剂量指标.方法 在21个体检年度分别对每个研究对象的每次体检时估算区域浓度、8 h时间加权平均浓度(TWA8)、年度接触水平和累积接触水平.将接触水平定义为协变量,白细胞计数定义为效应变量,用混合效应模型分析剂量效应关系.结果 共观察接苯对象147名26 292人月,白细胞计数样本1 147份、对照组66名14112人月白细胞计数样本396份.接触组、对照组白细胞计数平均水平分别为5.36×109,6.13×109/L.平均区域浓度、TWA8、年度接触水平和累积接触水平分别为5.10 mg/m3,4.69 mg/m3,72.90 mg/m3·月,783.70 mg/m3·月.4个混合效应模型均能收敛,其中以TWA8信息标准值最低.工人接苯水平增加、接触时间增长,白细胞水平下降.性别、吸烟与否对白细胞水平无明显影响.结论 工人接苯水平和时间明显影响工人白细胞水平,TWA8可能是最适接触剂量指标.     

接触乙烯类或苯类对孕妇及新生儿姊妹染色单体交换和微核的影响

取因职业而接触乙烯类或苯类的孕妇静脉血和他们新生儿脐带血进行ＳＣＥ和ＭＮ测定。发现接触乙烯类或苯类的母血ＳＣＥ（８．５５±０．８４，９．４４±１．１２）均高于对照组（７．６８±１．４０），他们新生儿脐带血ＳＣＥ（８．９４±１．４３，８．７５±０．８８）也高于对照组（６．７１±１．２７）。接触乙烯类和苯类的母血微核率（０．８３３‰，０．７２７‰），高于对照组（０．２６７‰），他们新生儿脐血微核率（０．７５‰，０．８１８‰）也高于对照组（０．２６７‰）。我们还发现母亲孕期被动吸烟增强了这两类诱变剂对他们后代的遗传毒性。     

天津市和平区苯作业场所空气中苯浓度调查

目的：了解苯作业场所空气中苯浓度,推测苯作业发展趋势,方法：采用和平区1993－1999年39家工业企业,220个苯作业点,660个空气样品中的苯浓度值,按不同作业工种分为油漆组,化工（原料）组,粘胶组及印刷组,通过成组设计的多个样本比较的秩和检验进行分析。结果：1997年内不同作业组空气中苯平均浓度差异有显著性（H＝8．00000 P＜0．05）,印刷组苯平均浓度高于其它作业组,其余年度中差异无显著性（P＞0．05）,1993－1999年,印刷组苯作业场所的苯平均浓度差异无显著性（P＞0．05）,结论：和平区苯作业开始由较低浓度过渡到较高浓度,以油漆业为主过渡到以印刷业为主,并且,1997年印刷组苯平均浓度超过国家卫生标准,应引起重视。     

Volatile organic compounds in the blood of persons in Kuwait during the oil fires

Between March and November of 1991, approximately 9000 workers from 43 different countries battled the burning oil wells in Kuwait. To document the exposure of persons in Kuwait during the oil well fires to volatile organic compounds (VOCs), we obtained samples of blood from 14 U.S. personnel in Kuwait City in May of 1991 (group I) and 40 American firefighters working in the oil fields in October of 1991 (group II). Concentrations of VOCs in group I and group II were compared with those of a random sample of 114 persons in the United States (reference group). The median concentrations of VOCs in group I were equal to or lower than those in the reference group. We found significant differences between the median concentrations of several VOCs in group 11 and the reference group. Median levels of ethylbenzene were about 10 times higher among group II than among the reference group (0.53 g/I vs 0.052 g/l). Median levels of benzene, m-/p-xylene, o-xylene, styrene, and toluene among group II were more than double those of the reference group. Although firefighters had higher median concentrations of VOCs than the reference group, those American personnel in Kuwait not involved in fighting the oil fires had concentrations of VOCs comparable to those in the reference group. Blood VOC measurements indicate a significant increase in exposure to VOCs in firefighters, but do not demonstrate this in personnel in Kuwait City.     

苯及其代谢产物在小鼠骨髓中形成DNA加合物的实验研究

目的　观察苯及其主要代谢产物苯酚、氢醌、苯醌及苯酚和氢醌联合染毒在小鼠骨髓中形成的 Ｄ Ｎ Ａ 加合物及其髓性毒性。方法　改进的３２ Ｐ 后标记方法。结果　苯及其主要代谢产物均能在小鼠骨髓细胞中形成至少１ 种 Ｄ Ｎ Ａ 加合物,相对加合物水平从０ ．８５ ×１０ － ８ ～６ ．７８ ×１０ － ８ 不等。骨髓细胞计数结果表明：单独染苯酚或氢醌,对小鼠骨髓细胞均没有抑制作用,但二者联合染毒对小鼠却表现出增强的髓性毒作用。结论　苯及其主要代谢产物均能在小鼠骨髓细胞中形成 Ｄ Ｎ Ａ 加合物,苯的代谢产物形成的 Ｄ Ｎ Ａ 加合物与髓性毒性有关。     

Occupational chronic exposure to organic solvents

Summary A group of printing workers (n = 34) exposed to toluene was examined according to the concentrations of hippuric acid, phenol, o-cresol, and (m+p)-cresol in urine. The average concentration in the air of the workroom was 23 ppm. It is shown that, besides hippuric acid, small amounts of o-cresol. which is not a normal constituent of urine, were formed from toluene. The occurrence of o-cresol could be proved by mass spectrometry. On account of the small amounts of benzene present in industrially used toluene—in this case 0.025%—the average concentration of phenol in urine of the exposed group was significantly higher statistically than in urine from the controls .     

Effect of phenobarbital pretreatment on in vitro enzyme kinetics and in vivo biotransformation of benzene in the rat

Phenobarbital pretreatment (50 mg/kg/day for 3 days orally) of male Wistar rats increased V _max of benzene in vitro hepatic microsomal biotransformation about 6-fold without changing K _m . However, benzene blood levels after oral, intraperitoneal, or subcutaneous benzene administration (3–3.5 mmoles/kg) were not influenced by phenobarbital pretreatment. The phenol blood levels after oral or intraperitoneal benzene were increased by phenobarbital pretreatment, but less than expected from in vitro data and only 3 h after benzene administration. Phenol elimination in urine after subcutaneous benzene was not affected by phenobarbital. After oral or intraperitoneal benzene administration, phenol urine excretion closely followed the levels of phenol in blood, i.e., rate of phenol urine excretion was significantly, but shortly increased, and the cumulative urine excretion of phenol increased very little or remained unchanged. Differences between the in vitro and in vivo observations of the effect of phenolbarbital on benzene biotransformation may partly be explained by distribution of benzene, which apparently limited benzene availability for biotransformation (V _d =5.5) and caused rapid decrease of benzene concentrations in blood. Conditions for enzyme activity may have been substantially different in vitro vs. in vivo: in vitro concentrations of benzene were at least by an order of magnitude higher than phenol concentrations, while in vivo, an opposite relation prevailed making a competition for microsomal monooxygenase possible. Cofactor availability may be another rate-limiting step or factor of in vivo benzene biotransformation, as benzene ring hydroxylation requires high energy. The rate of in vitro hepatic microsomal benzene biotransformation proved to be of limited value when predicting benzene quantitative biotransformation in vivo in contradistinction to various substrates where the in vitro and in vivo biotransformation data are in good agreement     

西安市饮用水中六六六滴滴涕污染的调查研究

为研究有机氯农药对西安市饮用水的污染状况，用气相色谱法测定了西安市２１个点自备井水中六六六，滴滴涕的含量。结果表明，２１个采样点饮用水中六六六的检出率为１００％，滴滴涕的检出率为１４．３％，结果提示六六六，滴滴涕的化学性质稳定及残留性所引起的远期危害不容忽视。