Xiaodong Tan

Cross-sectional study of cardiovascular effects of carbon disulfide among Chinese workers of a viscose factory

OBJECTIVE This cross-sectional study investigates the cardiovascular effects among Chinese workers who were occupationally exposed to carbon disulfide (CS2), and evaluates the protective value of the current Chinese Maximum Allowable Concentration (MAC) of CS2 against cardiovascular effects. METHODS The measurements of exposure were performed by personal sampling and gas chromatography. The biological monitoring was performed by HPLC. Three hundred and sixty-seven exposed workers and 125 reference workers (never exposed to CS2,) were included in this study. The exposed workers were divided into 2 sub-groups according to their cumulative exposure indices, the cut-off point being at 100 which means 10 years exposure to the Chinese Maximum Allowable Concentration in the workplace (10 mg/m3). All subjects were examined using a self-administered questionnaire including medical and job history, clinical complaints in the previous three months, and underwent a clinical check-up and a 12 lead electrocardiography (ECG) at rest, coded according to the Minnesota code. Blood pressure (BP) was recorded and blood samples were collected for lipid measurements. RESULTS The personal monitoring showed that the exposures levels (15.47 +/- 2.34 mg/m3) were below the Threshold Limit Value (TLV, 31 mg/m3), and most of the samples analyzed still showed higher values than the Chinese MAC (10 mg/m3). Clinical complaints and abnormal electrocardiograms were not significantly increased in exposed workers. No significant effect of CS2 on blood pressure, cholesterol, HDL and LDL cholesterol or triglycerides was found. Further studies are recommended to elucidate the mechanism of cardiac intoxication after CS2 exposure. CONCLUSION This study showed that Chinese workers exposed to CS2 did not have more clinical complaints, nor more ECG abnormalities than controls and no adverse effects were found in their lipids at an exposure level below the current TLV. The present results indicate that differences of health effects reported worldwide are possibly due to different exposure levels. They also indicate that the current Chinese MAC (10 mg/m3) sufficiently protects workers against negative cardiovascular effects.

Cardiovascular effects of carbon disulfide: meta-analysis of cohort studies

Objectives were to review the evidence of cardiovascular effects of carbon disulfide (CS2) on exposed workers from different cohort studies. Databases searched included MEDLINE, TOXLINE, and OSHtM Database (CD-ROM). Reference lists of reports and reviews were also searched. To be included in the analysis, a study had to have been a cohort study on cardiovascular effects of carbon disulfide with at least one outcome of interest. Every report was independently read using the Lichtenstein scale, General information of each study and relative risk estimates were calculated with 95% confidence intervals using the fixed-effects model. Pooled relative risks were calculated by the Dersimonian-Laird method basing on the random-effects model. Eleven cohort studies were identified in an extensive literature review. Pooled RR value was 1.56 and its 95% confidence interval was from 1.12 to 2.1, which showed CS2 exposure has feeble correlation with the prevalence of cardiovascular diseases. It is proved that meta-analysis is a sensitive method for combining different results in occupational epidemiology.

Candidate EPA, NIOSH method for determining carbon disulfide in air with capillary gas chromatography by orthogonal design.

This paper describes a candidate NIOSH EPA method for the determination of carbon disulfide in the air of workplaces with capillary gas chromatography using an orthogonal design. This method is designed to replace the packed column of the NIOSH method with a capillary column. The first part of this work concerned the setup of the method, particularly the choice of chromatographic parameters and finding their main favorable working ranges. The second part, using the statistical method orthogonal design, focused on optimizing the GC conditions, which were: column temperature, T(c) = 90 degrees C; injector temperature, T(i) = 140 degrees C; U section detector temperature, FPDU = 160 degrees C; L section detector temperature, FPDL = 210 degrees C; flow rate of carrier gas, F(c) = 20 cm/s; split ratio = 1/70; and injection volume = 1 microL. The quality control test showed that the coefficient of intra-day variation (CV) was 2.21%. A good logarithm linear correlation between the standard solutions and their peak areas was obtained. In general, the method reported here seems a valid candidate for a NIOSH EPA method due to its high precision and accuracy.

Comparison of Occupational Exposure to Carbon Disulphide in a Viscose Rayon Factory Before and After Technical Adjustments

The objective of this follow-up study was to verify the efficacy of the technical adjustments gradually introduced in departments of a viscose rayon factory from 1989 onward. Personal exposure to carbon disulphide was assessed by means of personal monitoring through active sampling. Six job titles in three departments of the factory were sampled. Geometric means were calculated and used as estimates of time-weighted average (TWA) concentrations. The results from the present study were compared with similar measurements from a previous study in the same factory. Due to organizational changes, only three job titles (spinner, first spinner, and viscose preparator) could be compared directly. Two new job titles were identified, although tasks performed in these two job titles already existed. The measurements from one job title could not be compared, due to a substantial reorganization and automation of the tasks carried out in the department. The comparison before and after technical improvements shows that personal exposure of spinner and first spinner has been substantially reduced. Even the geometric means of measurements outside the fresh air mask are below the TWA-TLV (Threshold Limit Value). Despite the difficulties in comparing the results from the two studies, it is concluded that the technical measures reduced up to tenfold personal exposure to carbon disulphide and personal protection reduced it further by a factor two.

Carbon disulfide at a Chinese viscose factory external and internal exposure assessment.

This article presents the results of carbon disulfide exposure measurements in a Chinese viscose rayon factory. The objectives of the study were to identify the external exposure levels at a large factory and to investigate the 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the subjects who were exposed to carbon disulfide in the working place atmosphere. The metabolism of carbon disulfide in the exposed subjects was also studied in order to demonstrate the best points in time for the internal exposure sampling. The measurement of the amount of personal exposure to carbon disulfide in the air of the workplace was performed by GC-FPD; the presence of TTCA in the workers urine was analyzed by use of a modified HPLC method. The kinetics of TTCA excretion was studied by analyses at different time-points both during and after exposure to carbon disulfide in the subjects. A total of 155 personal samples were obtained. The carbon disulfide concentration in the staple viscose hall was 13.72 +/- 1.12 mg m-3 in terms of the geometric mean +/- geometric standard deviation, and was 20.05 +/- 1.33 mg m-3 in the filament spinning hall. The TTCA values in the subjects who worked in the staple spinning hall were 1.18 +/- 0.43 mg g-1 creatinine and 1.07 +/- 0.38 mg g-1 creatinine for subjects working in the filament spinning hall. The best time for TTCA sampling is at the end of the working shift, the TTCA excretion was stable for a period of 4-12 h after exposure of the subjects to the carbon disulfide. It might be that the Chinese have different anthropometric characteristics; a sampling bias may therefore appear among different races.

Carbon disulfide cytotoxicity on cultured cardiac myocyte cell of rats

Although mostly epidemiological studies suggested that carbon disulfide produces cardiovascular effects in occupationally exposed workers, little is known about its cellular mechanism. The purpose of the present study was to evaluate the functional and histological effects on cardiac myocytes cultured under the condition of carbon disulfide exposure. Cardiac myocytes were isolated from neonatal rat ventricles by trypsin dispersion and cultured for 3 days in a full (Dulbeccos modified eagle medium) medium containing 2% calf serum. Thereafter the myocytes (10(6) myocytes/culture flask) were incubated with carbon disulfide at (CS(2)) the concentrations of 0, 20, 40, and 80 micromol/mL) for 24h. The beating arrest rate of myocytes for each group was examined and succinodehydrogenase (SDH) activity in the myocardial cells was also assessed by cytochemical method, and morphological examination was also performed. We found that the beating arrest rate of cardiac myocytes increased with increasing exposure levels. Vacuolization and pseudopodia may be seen in the cytoplasm of exposure group. SDH activity decreased with increasing exposure levels. The results suggested that CS(2) has a direct cytotoxic effect which is dose dependent. The biochemical mechanism may be a reduction of the availability of energy of the cardiac cytocyte in the form of ATP, resulting in a decrease of contractility by lacking of energy.

Cross-sectional study of the ophthalmological effects of carbon disulfide in Chinese viscose workers

This article presents cross-sectional investigation results of ophthalmological effects for the occupational exposure to carbon disulfide of workers at a large viscose fibre factory in the middle part of China. The total of 271 exposed subjects (191 males, 80 females) and 133 workers (93 males, 40 females) not exposed to any toxic agent in the working environment underwent ophthalmological examination. The self-administered questionnaire collected data on the medical history and ophthalmological complaints during the past three months. The ophthalmologic examination included routine examination for retinal capillary anomalies and and color vision with the FM 100-Hue test method. Nearly all subjects did not use respirators, smocks or aprons, gloves or other personal protective devices during work time. The average personal CS2 exposure level in the present study was 13.7-20.05 mg/m3. The FM 100-Hue test results showed that the total error scores of the exposed group, whether male or female, were higher than that of the control, the discrimination of the green and blue zones was also impaired significantly. A fundus examination showed no retinal capillary anomalies or other serious ophthalmological symptoms that may be related to effects of CS2. In conclusion, color vision was disturbed in workers exposed to CS2, at levels below the present threshold value. Reduced color discrimination may be attributed to long-term carbon disulfide exposure and suggests that health surveillance of workers exposed to carbon disulfide should include the FM 100-Hue Test as a sensitive and easy method.