Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene

Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol related linearly to the intensity of exposure to benzene both in men and women among workers exposed to benzene, and was suppressed by toluene co-exposure among male workers exposed to a mixture of benzene and toluene. A cross sectional balance study in men at the end of the shift of a workday showed that only 0.47% of benzene absorbed will be excreted into urine as 1,2,4-benzenetriol, in close agreement with previous results in rabbits fed benzene. The concentration of 1,2,4-benzenetriol in urine was more closely related to the concentration of quinol than that of catechol. The fact that phenol and quinol, but not catechol, are precursors of 1,2,4-benzentriol in urine was further confirmed by the intraperitoneal injection of the three phenolic compounds to rats followed by urine analysis for 1,2,4-benzenetriol.     

Determination of catechol and quinol in the urine of workers exposed to benzene

Time weighted average concentrations of benzene in breathing zone air (measured by diffusive sampling coupled with FID gas chromatography) and concentrations of catechol and quinol in the urine (collected at about 1500 in the second half of a working week and analysed by high performance liquid chromatography) were compared in 152 workers who were exposed to benzene (64 men, 88 women). The concentration of urinary metabolites was also determined in 131 non-exposed subjects (43 men, 88 women). There was a linear relation between the benzene concentrations in the breathing zone and the urinary concentrations of catechol and quinol (with or without correction for urine density) in both sexes. Neither catechol nor quinol concentration was able to separate those exposed to benzene at 10 ppm from those without exposure. The data indicated that when workers were exposed to benzene at 100 ppm about 25% of benzene absorbed was excreted into the urine as phenolic metabolites, of which 13.2%, 1.6%, and 10.2% are phenol, catechol, and quinol, respectively.     

Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene.

Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol related linearly to the intensity of exposure to benzene both in men and women among workers exposed to benzene, and was suppressed by toluene co-exposure among male workers exposed to a mixture of benzene and toluene. A cross sectional balance study in men at the end of the shift of a workday showed that only 0.47% of benzene absorbed will be excreted into urine as 1,2,4-benzenetriol, in close agreement with previous results in rabbits fed benzene. The concentration of 1,2,4-benzenetriol in urine was more closely related to the concentration of quinol than that of catechol. The fact that phenol and quinol, but not catechol, are precursors of 1,2,4-benzentriol in urine was further confirmed by the intraperitoneal injection of the three phenolic compounds to rats followed by urine analysis for 1,2,4-benzenetriol.     

Diazo-positive metabolites in urine from workers exposed to aromatic nitro-amino compounds

Summary The amount of diazo-positive compounds in urine from workers at a chemical plant producing pharmaceuticals and explosives was determined in samples collected after work and after a holiday. Forty-five persons working with aromatic nitro-amino compounds (ANA) showed a statistically significant (p < 0.01) increase in the exposed samples (1.21 ± 1.40 mmol/mol creatinine) compared to the unexposed samples (0.56 ± 0.31 mmol/mol creatinine). No increase in the level of diazo-positive metabolites was found in the 25 workers not exposed to ANA compounds. In a follow-up study, 32 trinitrotoluene (TNT) workers were divided into three exposure categories and seemed to show a dose-dependent increase in the level of urinary diazopositive metabolites. However, there was a considerable interindividual variation. The method seems suitable for the biological assessment of exposure to ANA compounds — at least on a group level. This may be valuable, especially in situations where significant dermal uptake is expected.     

Evaluation of exposure biomarkers in offshore workers exposed to low benzene and toluene concentrations

Purpose  

Characterize ethylbenzene and xylene air concentrations, and explore the biological exposure markers (urinary t,t-muconic acid (t,t-MA) and unmetabolized toluene) among petroleum workers offshore. Offshore workers have increased health risks due to simultaneous exposures to several hydrocarbons present in crude oil. We discuss the pooled benzene exposure results from our previous and current studies and possible co-exposure interactions.     

Determination of catechol and quinol in the urine of workers exposed to benzene.

Time weighted average concentrations of benzene in breathing zone air (measured by diffusive sampling coupled with FID gas chromatography) and concentrations of catechol and quinol in the urine (collected at about 1500 in the second half of a working week and analysed by high performance liquid chromatography) were compared in 152 workers who were exposed to benzene (64 men, 88 women). The concentration of urinary metabolites was also determined in 131 non-exposed subjects (43 men, 88 women). There was a linear relation between the benzene concentrations in the breathing zone and the urinary concentrations of catechol and quinol (with or without correction for urine density) in both sexes. Neither catechol nor quinol concentration was able to separate those exposed to benzene at 10 ppm from those without exposure. The data indicated that when workers were exposed to benzene at 100 ppm about 25% of benzene absorbed was excreted into the urine as phenolic metabolites, of which 13.2%, 1.6%, and 10.2% are phenol, catechol, and quinol, respectively.     

职业接触苯工人尿中黏糠酸测定方法与生物限值研究

目的推荐我国职业接触苯尿中反-反式黏糠酸（uMA）生物限值并建立相应的高效液相色谱（HPLC）测定方法。方法选择职业苯接触者56人和非苯接触者24人，应用活性炭吸附管采集工人呼吸带空气、CS2洗脱、毛细管气相色谱法检测个体外暴露水平，同时采集当日工作班前和班末尿样本，应用HPLC测定尿中uMA以观察内暴露水平。尿样经2mol／L盐酸酸化、香草酸为内标、乙酸乙酯萃取预处理，采用ODS柱、冰乙酸：四氢呋喃：甲醇：水（体积比1：2：10：87）为流动相、流速0．9ml／min、紫外检验波长264nm、柱温25℃的色谱条件分离测定尿中uMA。结果uMA的线性范围为0．10～10．00mg／L，检出限为0．10mg／L，加标平均回收率为95．1％～100．5％，批内、批间精密度变异系数分别为4．4％～7．5％和6．2％～8．8％。接苯工人空气苯浓度范围0．332～146．000mg／m^3，平均浓度41．8mg／m^3，班末尿uMA与个体苯接触量存在良好线性关系y（mg／gCr）=2．103＋0．177x（mg／m^3），r=0．791，P〈0．01，将我国职业苯接触限值PC—TWA=6mg／m^3代入回归方程，推算工作班末尿中uMA含量为3．165mg／gCr。结论建立的HPLC测定uMA方法简便、快速、灵敏，可用于职业接触苯的生物监测，参考国内外文献和国外相关标准，建议我国职业接触苯生物限值班末尿uMA为2．4mmol／molCr（3．0mg／gCr）。     

Trichloro-compounds in the urine of humans exposed to methyl chloroform at sub-threshold levels

Summary Survey was carried out in 4 intaglio printing factories where methyl chloroform, the sole organic solvent in the entire process, was employed to remove excess ink. The medical interview and clinico-laboratory examinations revealed no dose-consistent adverse effects among the four groups of workers who had been exposed at the average concentrations of 4, 25, 28 and 53 ppm, respectively. Linear relationship was observed between environmental vapour concentrations and total trichloro-compounds levels in the urine of workers exposed. Increased levels of urinary metabolites towards the week-end, together with the biological half-life of 8.7 hrs as measured from the decrease in the urinary metabolites, suggested the storage of methyl chloroform in the body after repeated exposures. Perusal of previous reports as well as present results regarding toxic potency of methyl chloroform supports, with emphasis of possible accumulation, the German threshold of 200 ppm as a tentative value of choice for the time being.A part of this work was presented at the 46th Annual Meeting of the Japanese Association of Industrial Health, Osaka, April 6–8, 1973.     

Genotoxic effects in peripheral blood and urine of workers exposed to low level benzene.

Blood samples were obtained from a population of refinery workers representing different age groups. Sixty six men with low average exposure to benzene and 33 male controls were investigated. An examination of cell cycle kinetics and sister chromatid exchange was carried out on control and exposed individuals. No significant differences were found between groups of individuals varying in their drinking and smoking habits or their exposure to diagnostic x rays. Individuals with the lowest and highest phenol values were examined for urine mutagenicity, with urinary phenol used here as an indicator of benzene exposure. There was no difference in the number of revertant colonies in strains TA98 and 100 between the high and low urinary phenol groups. There were also no differences in any of the biochemical measures or haematological parameters investigated in all the individuals except that higher values for mean corpuscular volume were found in exposed than in control individuals. These values, however, were within the normal clinical range.     

1,3-丁二烯作业工人尿中生物标志物的研究

目的 探讨1,3-丁二烯(BD)接触工人的内剂量生物标志物,为BD接触工人生物限值的制定提供基础依据.方法 选择某橡胶厂BD接触工人44名作为接触组,不接触BD的25人为对照组(同一企业锅炉车间工人12名,为内对照;某机构文员13名,为外对照).收集班末尿,用固相微萃取柱对尿液进行处理,UPLC-MS/MS检测,同位素内标定量尿液中BD代谢产物3,4-二羟基硫尿酸(DHBMA)和1-羟甲基-2-苯硫酚尿酸(MHBMA)的浓度,同时用气相色谱-火焰离子化检测器测定工人作业场所空气中BD浓度,比较其内外暴露指标间的相关性.尿中DHBMA和MHBMA及空气中BD测 定数据均经对数转换后统计分析.结果 接触组尿中DHBMA [(2.51 ±0.44) μg/L]和(MHBMA+DHBMA)[(2.68±0.27) μg/L]明显高于对照组[DHBMA:(2.20±0.25) μg/L,(MHBMA+DHBMA):(2.49±0.34) μg/L],差异有统计学意义(P＜0.01);尿中DHBMA的含量受空气中BD浓度影响明显(r=0.539,P=0.001),回归方程为y=2.417 +0.520x,模型的调整R2为0.262;尿中MHBMA不受到吸烟、饮酒和工龄的影响.结论 在职业环境暴露水平下,班末尿中DHBMA可以作为BD接触的内剂量标志物.     

Monitoring of formic acid in urine of humans exposed to low levels of formaldehyde

This study documented the formaldehyde exposures of a group of veterinary medicine students. It also investigated the feasibility of biologically monitoring the exposures. The biological monitoring was based on the fact that the formaldehyde is metabolized in the body to formic acid, and may then be excreted in the urine. Therefore, exposures to formaldehyde could theoretically create a shift in the formic acid levels in the urine. Normal baseline levels of urinary formic acid were first established for each subject. The baselines of most students were quite variable. Very few exhibited a "tight variability" in their baseline. Next, three sets of pre- and post-exposure urine samples were taken. A series of paired t-tests were run on these "pre" and "post" sets. The results indicated that no significant formic acid shift was seen. A subset of the samples was "corrected" for specific gravity. However, this adjustment did not have an effect upon the relative formic acid levels. In addition, no significant formic acid shift was seen in the adjusted group. Exposure levels of the students were less than 0.5 ppm of formaldehyde. Therefore, the main conclusion of the study was that biological monitoring of formaldehyde exposures (via formic acid shifts) at these low levels was not a feasible technique.     

Benzidine and its acetylated metabolites in the urine of workers exposed to Direct Black 38

Urine samples of workers in a small-scale unit manufacturing Direct Black 38 were analyzed by high-pressure liquid chromatography for the presence of benzidine and mono and diacetyl benzidine. Acetylated metabolites were found in all the urine samples, and benzidine was found in all except two. Two workers excreted very high levels of benzidine and its metabolites in their urine. This study highlights the potential risk of bladder cancer in such units of developing countries where manufacture of benzidine-based dyes is yet to be regulated.     

Mutagenic activity and metabolites in the urine of workers exposed to trinitrotoluene (TNT).

Urine samples taken after work and after a free weekend from 50 workers employed in various activities in a chemical plant manufacturing explosives were analysed. On the basis of hygienic surveys, the subjects were divided into three categories of exposure to trinitrotoluene (TNT). The urine analyses consisted of gas chromatographic identification of TNT and its two metabolites, 4-ADNT and 2-ADNT, and a determination of the mutagenic activity. Two frame shift detector strains of Salmonella typhimurium were used, TA 98 and TA 98 NR, the latter being deficient in endogenous nitroreductase activity. On the basis of previous results on TNT mutagenicity, no exogeneous metabolic system was used to test the urine concentrates. Both tester strains showed that the mean urinary mutagenic activity was higher in the after work samples than in post weekend samples from the same subjects, showing that bacterial nitroreductase activity was not significantly responsible for the mutagenicity, although the response was higher with strain TA 98 than with TA 98 NR. The interindividual variation in urine mutagenicity was high, however, and the difference between the two sampling times was statistically significant (p less than 0.05) only for the high exposed group (workers in trotyl foundry and sieve house). Correlation between urinary mutagenicity and concentration of TNT in urine was poor; correlation was significant only with the urinary concentration of 4-ADNT. The correlation between urinary TNT and both metabolites was good (p less than 0.001). These results suggest that analysis of 4-ADNT in urine would be a sufficient biological measure for controlling exposure to TNT.     

Mutagenic activity and metabolites in the urine of workers exposed to trinitrotoluene (TNT)

Urine samples taken after work and after a free weekend from 50 workers employed in various activities in a chemical plant manufacturing explosives were analysed. On the basis of hygienic surveys, the subjects were divided into three categories of exposure to trinitrotoluene (TNT). The urine analyses consisted of gas chromatographic identification of TNT and its two metabolites, 4-ADNT and 2-ADNT, and a determination of the mutagenic activity. Two frame shift detector strains of Salmonella typhimurium were used, TA 98 and TA 98 NR, the latter being deficient in endogenous nitroreductase activity. On the basis of previous results on TNT mutagenicity, no exogeneous metabolic system was used to test the urine concentrates. Both tester strains showed that the mean urinary mutagenic activity was higher in the after work samples than in post weekend samples from the same subjects, showing that bacterial nitroreductase activity was not significantly responsible for the mutagenicity, although the response was higher with strain TA 98 than with TA 98 NR. The interindividual variation in urine mutagenicity was high, however, and the difference between the two sampling times was statistically significant (p less than 0.05) only for the high exposed group (workers in trotyl foundry and sieve house). Correlation between urinary mutagenicity and concentration of TNT in urine was poor; correlation was significant only with the urinary concentration of 4-ADNT. The correlation between urinary TNT and both metabolites was good (p less than 0.001). These results suggest that analysis of 4-ADNT in urine would be a sufficient biological measure for controlling exposure to TNT.     

苯的两种生物标志物现场应用价值的比较

选择了８６名苯接触工人进行现场研究。结果表明当空气苯浓度的几何均值为３１．８６ｍｇ／ｍ３时，代谢物粘康酸的几何均值为３．１５３ｍｇ／ｇ，尿酚则为３１．０２７ｍｇ／ｇ。接触的空气苯浓度分别与代谢物粘康酸和尿酚之间的相关系数为０．９０１２、０．７３０１。接触低浓度苯的人群尿酚与外接触的苯水平相关性较差；但粘康酸无论是在接触高的或低的苯浓度情况下，二者之间均有良好的相关性。粘康酸在对照组检出水平极低。提示：粘康酸可替代尿酚作为苯的生物学监测指标     

高效液相色谱-二极管阵列检测法同时分析尿中苯系物的代谢产物

摘要:目的　本文建立了一种快速同时分析尿中苯系物代谢产物的高效液相色谱法。方法　样品用1 mol/L盐酸酸化后,加入氯仿:异丙醇（5∶1）提取,离心后,取有机相吹干,流动相溶解残渣,上清液进样。经甲醇-0.3%乙酸洗脱,反相C18柱分离,紫外检测器在205 nm和254 nm波长处测定代谢产物含量。结果　各代谢产物测定的最低检出限为5.0～32 μg/L,标准溶液测定的相对标准偏差（Relative Standard Deviation,RSDs）为1.89%～4.52%。将所建立的方法用于实际尿样的测定,取得了较为满意的效果,样品测定的RSDs为3.96%～9.88%,平均加标回收率为83.5%～106%。结论　本法快速准确,20 min内可完成一次分析,适用于尿液中苯系物代谢物含量的同时分析。     

Muconic acid determinations in urine as a biological exposure index for workers occupationally exposed to benzene.

Urinary phenol determinations have traditionally been used to monitor high levels of occupational benzene exposure, but the same technique cannot be used to monitor low-level exposures because of the high background of phenol resulting from its presence in many foods and from metabolism of aromatic amino acids. Thus, new biological indexes for exposure to low levels of benzene are needed. Animal studies indicate that muconic acid is a metabolite of benzene that is excreted in the urine as an increasing fraction of the total benzene metabolites with decreasing dose of benzene. Thus, urinary muconic acid is potentially useful as a monitor for low levels of exposure to benzene. It is also of interest to determine the level of muconic acid in the urine of humans exposed to benzene for comparison with animal data as an aid for use of the animal studies in risk assessments for humans. This report describes the development of a gas chromatography/mass spectrometry assay to detect and quantitate the benzene metabolite, muconic acid, in urine. The internal standard used in the assay, muconic acid-d4, was biosynthesized by F344/N rats administered benzene-d6 by gavage; the muconic acid was isolated from the rat's urine. Muconic acid was measured in experimental urine samples by adding the internal standard, followed by extraction and derivatization. Phenol was also measured in urine after extraction and derivatization. The assays were applied to the urine samples from 14 workers occupationally exposed to benzene and 8 workers with no known benzene exposure. Muconic acid could be detected in all of the urine samples at levels greater than 100 ng/mL.(ABSTRACT TRUNCATED AT 250 WORDS)     

苯职业接触工人尿中酚和黏糠酸监测结果及意义

目的通过对苯接触工人尿中酚和反-反式黏糠酸的监测与分析,开展低苯环境下苯接触生物标志物研究,并探讨其实际应用价值。方法选取某制鞋厂员工作为研究对象,测定其尿液中酚和反-反式黏糠酸浓度,并对作业工人工作场所中苯浓度进行监测。结果接苯工人尿酚浓度与接苯浓度无显著性相关关系,尿中反-反式黏糠酸浓度与接苯浓度存在显著正相关(P0.05),接苯工人班后尿中的反-反式黏糠酸浓度显著高于班前尿(P0.05),吸烟对尿酚浓度影响较小,吸烟者尿中反-反式黏糠酸浓度显著高于非吸烟者(P0.05)。结论低浓度苯工作环境下,尿中反-反式黏糠酸可以作为一种敏感的生物标志物替代尿酚反映机体苯暴露情况。     

An improved method for the determination of phenol in the urine of workers exposed to benzene or phenol

Summary Interlaboratory comparison of phenol in urine analyses shows large variability, much larger than is normally associated with gas chromatographic analysis which suggest sample preparation problems are to blame. This paper describes a simple method of analysis which has been in use for four years in our laboratory. 2-Ethyl phenol is added to the urine as an internal standard; the sample is distilled and the distillate directly analysed by gas chromatography on a column packed with Tenax-GC using FID detectors. The detection limit is 0.1 mg/l and the coefficient of variation at 5.9 mg/l is 4.1 % (n = 8).     

Cytogenetic study of workers exposed to benzene

Cytogenetic evaluation of peripheral lymphocytes from 52 workers exposed to low levels of benzene (less than 10 ppm) has revealed an increase in aberration rates as compared to that of a 44-person group seen for preemployment examination. Statistically significant differences were found in the distribution of specific types of chromosomal aberrations. These induced-aberrations levels were not related to the age of the workers. Continued study of benzene-exposed workers (as well as industrial populations exposed to any clastogenic agent) with medical cytogenetic surveillance, environmental monitoring, and lifetime epidemiologic investigation is recommended.