Carbon disulphide: IV. Cardiovascular function in workers in the viscose industry

Electrocardiographic Abnormality for Workers Exposed to Carbon Disulfide at a Viscose Rayon Plant

OBJECTIVE

This study investigated electrocardiography (ECG) manifestations for male workers with carbon disulfide exposure at rayon manufacturing plants.

METHODS

A total of 251 men in the exposure group and 226 administrative clerks in the reference group received physical examinations and completed questionnaires.

RESULTS

The prevalence of ECG abnormalities was much higher in the carbon disulfide exposure group (25.9%, n = 65) than in the reference group (2.7%, n = 6), with an odds ratio (OR) of 12.8 (95% confidence interval [CI] = 5.4-30.2). The foremen were at the highest risk of abnormal ECG (OR = 20.6, 95% CI = 6.5-65.2), followed by filament-spinning workers (OR = 14.2, 95% CI = 5.7-35.3), viscose-manufacturing workers (OR = 11.3, 95% CI = 4.3-30.1), and carbon disulfide-manufacturing workers (OR = 8.1, 95% CI = 2.7-25.6). The multivariate logistic regression analysis based on cumulative exposure index also showed a dose-response relationship with the exposure, and the risk of ECG abnormality could be initiated at the exposure history of 31 to 57 year-ppm with an OR of 7.2 (95% CI = 1.5-36.7).

CONCLUSIONS

In general, the ECG abnormalities observed in workers at the permissible exposure level of carbon disulfide implicate the importance of environmental control of the chemical and of workers' education in exposure prevention at work.

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.

Carbon disulfide cytotoxicity on cultured cardiac myocytes of rats

Although epidemiological studies have 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 a condition of carbon disulfide exposure. Cardiac myocytes were isolated from neonatal rat ventricles by trypsin, dispersed and cultured for 3 days in a full Dulbecco's Modified Eagle Medium containing 2% calf serum. Then the myocytes (10(6) myocytes/mL) were incubated with carbon disulfide at concentrations of 0, 20, 40, and 80 micromol/mL for 24 h. The beating arrest rate of myocytes for each group was examined, succinodehydrogenase (SDH) activity in the myocardial cells was assessed using a cytochemical method, and a morphological examination was performed. We found that the beating arrest rate of cardiac myocytes increased with increasing exposure levels. Vacuolization and pseudopodia could be seen in the cytoplasm of the exposed group. SDH activity decreased with increasing exposure levels. The results suggest that CS2 has a direct and dose-dependent cytotoxic effect. The biochemical mechanism may be a reduction of the availability of energy (adenosine triphosphate) to cardiac myocytes, resulting in a decrease of contractility by lack of energy.