Toluene vapor exposure and urinary excretion of hippuric acid among workers in China.

A factory survey was conducted in three provinces in China from 1985 to 1989. The time-weighted average toluene concentrations in breathing zone air were monitored by diffusive sampling, whereas hippuric acid (HA) concentrations in shift-end urine samples were measured by high performance liquid chromatography (HPLC). Exposed workers (456 men and women) were those for whom toluene (up to 548 ppm toluene) accounted for greater than or equal to 90% of total exposure (by vapor concentration in ppm), whereas 517 nonexposed controls were recruited from the same factories or from factories of the same region. There was a linear correlation between the intensity of toluene exposure and HA concentration in the shift-end urine. Comparison of the results with findings in the literature shows that the toluene-induced increase in urinary HA concentration among workers in China is significantly smaller than the published values, whereas HA concentrations in urine samples from nonexposed controls are comparable to the levels previously reported.     

Bulk and Solution Copolymerization of Butyl Acrylate/Methyl Methacrylate at Elevated Temperatures

A series of bulk and solution (in toluene) copolymerizations of butyl acrylate/methyl methacrylate were performed independently at two laboratories. The runs were at elevated temperatures ranging from 90 to 140 °C conducted to high conversion levels, and samples were characterized for conversion, cumulative copolymer composition and number‐ and weight‐average molecular weights and distribution. Variation of the comonomer feed composition, temperature, and the solvent, initiator and chain transfer agent concentrations was studied. Using a mechanistic model, conversion data were predicted to high conversions using terminal model kinetics at 90 and 115 °C. The copolymer composition data conformed to the terminal kinetic model over the entire temperature range. Solvent effects were reflected by changes in the butyl acrylate rate constants.

Composition vs. conversion. Effect of feed composition for runs at 140 °C.     

Effect of benzene and its homologs on unit activity in various brain structures

Department of Normal Physiology, Irkutsk Medical Institute (Presented by Academician of the Academy of Medical Sciences of the USSR K. V. Sudakov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 7, pp. 17–19, July, 1990.     

中药丸剂中水分的GC法测定

目的:对中药丸剂中水分含量用GC法进行了测定,考察了影响水分测定的多种因素。方法:采用甲苯法和GC法比较,GC法使用热导检测器(TCD),401有机担体柱(3 m×3 mm,80-100目),柱温:145℃,检测器温度:200℃,进样口温度:200℃,载气:氮气,流速30 mL·min-1。结果:GC法水的线性范围为2.151×10-3-2.151×10-2μg·μL-1(r=0.9993)。结论:气相色谱法测定快速、灵敏,成本较低,不污染环境。提供中国药典中成药蜜丸中水分测定法的修订参考。     

甲苯对原代培养海马神经细胞的毒性研究

目的　通过在体外对原代培养的海马神经细胞进行染毒 ,观察其对神经细胞的毒作用 ,并探讨其作用机制。方法　取新生的SD大鼠海马神经细胞进行原代培养 ,两周后 ,用甲苯染毒 ,分成 3个染毒组 ,染毒浓度分别为 3、6和 9mmol L ,并设空白对照组和赋形剂组 ,染毒 2 4h ,观察其对细胞形态、细胞存活率、LDH漏出率、细胞内游离钙和细胞凋亡的影响。结果　甲苯染毒后 ,细胞的形态发生改变 ,引起细胞突起萎缩 ,细胞肿胀变圆 ,细胞数量减少 ;神经细胞存活率的显著下降 ,且随着染毒时间的延长及浓度的升高其存活率逐渐降低 ;高剂量组神经细胞LDH漏出率的显著升高 ,与对照组相比有显著性 (P <0 0 5 ) ;细胞细胞内的[Ca2 + ]i浓度显著上升 ,与对照组相比P <0 0 5 ,并呈剂量依赖性的变化 ,加入钙通道拮抗剂硫氮卓酮后 ,则未见 [Ca2 + ]i浓度上升 ;可见明显的细胞凋亡。结论　甲苯体外染毒对神经细胞有较强的毒性。这可能与甲苯有较强的脂溶性、引起细胞钙内流增加 ,促进细胞凋亡有关。     

汽车内空气污染状况分析

目的 对新车内空气中苯、甲苯和甲醛浓度进行分析，了解其车内空气的污染程度。方法 采用甲醛分析仪，气相色谱仪进行测定。结果 65辆新车中甲醛、苯、甲苯的总合格率分别为85％、65％、58％。第2、3、4个月甲醛浓度合格率分别为81％、59％、91％；苯浓度合格率分别为66％、45％、82％；甲苯浓度合格率分别为38％、64％、73％。结论 甲醛超标程度较小，苯和甲苯超标比较严重。     

Toluene and methylethylketone: effect of combined exposure on their metabolism in rat

1.?Multiple exposures are ubiquitous in industrial environments. In this article, we highlight the risks faced by workers and complete the data available on the metabolic impact of a common mixture: toluene (TOL) and methylethylketone (MEK).

2.?Rats were exposed by inhalation under controlled conditions either to each solvent individually, or to mixtures of the two. How the interaction between the two solvents affected their fate in the blood and brain, their main relevant urinary metabolites (o-cresol, benzylmercapturic acid for TOL and 2,3-butanediols for MEK) and their hepatic metabolism were investigated.

3.?Although the cytochrome P450 concentration was unchanged, and the activities of CYP1A2 and CYP2E1 isoforms were not additively or synergistically induced by co-exposure, TOL metabolism was inhibited by the presence of MEK (and vice versa). Depending on the relative proportions of each compound in the mixture, this sometimes resulted in a large increase in blood and brain concentrations. Apart from extreme cases (unbalanced mixtures), the amount of o-cresol and benzylmercapturic acid (and to a lesser extent 2,3-butanediols) excreted were proportional to the blood solvent concentrations.

4.?In a co-exposure context, ortho-cresol and benzylmercapturic acid can be used as urinary biomarkers in biomonitoring for employees to relatively accurately assess TOL exposure.     

Respiratory health surveillance in a toluene di-isocyanate production unit, 1967-97: clinical observations and lung function analyses

OBJECTIVES—To characterise irritant and allergic airway responses and assess changes in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁) relative to exposure to toluene di-isocyanate (TDI).
METHODS—Employees (n=313) ever assigned to a TDI production unit for 3 months (1967-92) were identified from personnel records along with 158 frequency matched referents without known exposure to TDI. Reports made during visits to the occupational clinic of incidents related to exposure to TDI and annual periodic examination results (questionnaire, physical findings, and spirometry) were abstracted and assessed relative to industrial hygiene estimates of exposure to TDI.
RESULTS—Mean 8 hour time weighted average estimates of TDI concentrations ranged from 9.9 ppb in jobs with potentially high exposure during the early years of plant operations to 0.5 ppb in jobs with potentially low exposure in more recent years. The corresponding rates of visits to the clinic due to incidents of exposure to TDI (including both irritant and allergic airway responses) declined from 20.5 to 1.0 visits per 100 years of employment at the unit. The annual incidence of asthma induced by TDI declined from 1.8% before 1980 to 0.7% afterwards. Neither cross sectional nor longitudinal analyses of FVC and FEV₁ showed significant dose-response findings relative to exposure to TDI across the total exposed population. Among cases of occupational asthma there was an apparent initial decline in FEV₁ within 2 years of first reporting symptoms, but not an accelerated rate of decline in follow up tests from 4-30 years after induction of asthma.
CONCLUSIONS—Occurrences of both asthma induced by TDI and irritant airway responses due to exposure to TDI were found in this cohort, but there was no relation between cumulative exposure to TDI and irreversible airflow obstruction as assessed by spirometry.


Keywords: toluene di-isocyanate; lung function decrement; occupational asthma