Cardiovascular effects of occupational exposure to carbon disulphide

The objective of this study was to investigate the effect of occupational exposure to carbon disulphide (CS2) on the total cholesterol, blood pressure and prevalence of coronary heart disease (CHD). A cross-sectional study involving 252 viscose rayon workers and 252 age and sex matched controls was carried out. Depending on the job and specific work place, the CS2 concentrations were between 10 and 64 mg/m3. A cumulative exposure index (CS2 index) was calculated for each worker by multiplying the number of years he had held a particular job with the CS2 concentrations in that job. CHD prevalence among the exposed was higher than among the controls; the difference reaching significance only for highly exposed workers. Cholesterol levels were significantly higher in both highly and moderately exposed groups. In conclusion, the results demonstrated that occupational exposure to CS2 increases total cholesterol and the risk for CHD. While the risk for CHD is increased in workers exposed to high CS2 concentration for many years (CS2 index > or = 300), even the relatively modest exposure (CS2 < 300) may increase the serum cholesterol.     

TTCA measurements in biomonitoring of low-level exposure to carbon disulphide

Objectives: The biomonitoring of carbon disulphide exposure is currently performed by measuring the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) in the urine of exposed workers. Methods: In this study the effect of TTCA, which is found in some vegetables, on the biomonitoring of low-level carbon disulphide exposure was evaluated. In addition the upper reference limit (URL) of TTCA in the non-exposed Finnish population was estimated by analysing TTCA in urine samples from 116 people. The samples were collected at health centres all over Finland from people in employment and in the age group 24–64 years. The analytical measurements were made using a modern column-switching technique and the results were compared with those from the same samples using the extraction method generally in use and, until now, recommended for the determination of TTCA in urine. Results: The results obtained with the two analytical methods correlated very well with each other (r=0.9). The liquid-liquid extraction method gave results constantly about 3.5 μmol/l higher than the column-switching method. The results of this study also confirmed that many cruciferous vegetables (Cruciferae) contain endogenous TTCA (0.6–5.0 mg/kg), which is excreted unchanged in the urine. After a normal meal which included these vegetables, the TTCA concentration did not rise above the biomonitoring action level even if this was as low as 2 mmol/mol creatinine, but was easily above the URL of TTCA in the non-exposed population. The URL, calculated as the 95th percentile, was 0.3 mmol/mol creatinine. Conclusion: The results showed that the extraction method was not sufficiently specific or sensitive when the TTCA concentrations were lower than 10 μmol/l. In contrast, the column-switching method seemed to give reliable results even at these low levels, which are the levels of interest in current practice. Received: 29 September 1999 / Accepted: 27 December 1999     

Changes in zinc and serum proteins due to carbon disulphide exposure

El-Gazzar, R., El-Sadik, Y. M., and Hussein, M. (1973).British Journal of Industrial Medicine,30, 284-288. Changes in zinc and serum proteins due to carbon disulphide exposure. Serum zinc and proteins have been studied in 82 workers in the Egyptian rayon industry, of whom 40 were at the time exposed to carbon disulphide (CS₂) and nine had been exposed in the past for a year or more. Thirty-three workers without exposure were used as controls. Carbon disulphide caused depletion of serum zinc by an increase in the rate of zinc excretion and an increase in all serum protein fractions. All these effects are temporary and improve on cessation of exposure.     

Chronic peripheral neuropathy in workers with previous exposure to carbon disulphide.

Two groups of viscose rayon production workers were examined 10 years after discontinuation of exposure to CS2. Group A comprised 20 subjects exposed to high CS2 concentrations and group B 13 subjects with lower exposure. Clinical findings and the measurements of nerve conduction velocity of the slow fibres in the peripheral nerves were evaluated. Twelve subjects had both clinical and electromyographic evidence of neuropathy and 10 showed a diminution in motor conduction velocity. A relationship between the degrees of exposure to CS2 and prevalence of polyneuropathy was found. On re-examining 12 subjects with neuropathy who had been examined four years before no significant electromyographic improvement was observed. These findings are consistent with a permanent axonal neuropathy caused by carbon disulphide.     

Energy potential and hepatic function in rats under acute exposure to carbon disulphide

Summary In adult female rats 8-hr exposure to 400 ppm CS₂ did not produce a change in conventional liver function tests (SGOT, SGPT, and SLDH activities; BSP clearance in the bile). This would seem to imply that the severe inhibition of the hepatic mixed-function oxidases observed in earlier experiments after the same dose of CS₂ is not attributable to generalized cell damage, but should rather be taken to represent a selective lesion. Eight-hr exposures of the experimental animals to graded CS₂ concentrations ranging from 20 to 400 ppm triggered a rapidly reversible substantial depletion of the hepatic glycogen. A concurrent increase of the lactate and inorganic phosphate levels and also of the oxygen consumption was demonstrated, in conjunction with an increased respiratory uptake of oxygen by the exposed animals, a fall in body temperature, and a decrease of the serum potassium and calcium levels. These changes may be interpreted as an extensive defect in the energy supply in the liver cell. The concomitant slight decrease of the liver weight is largely explained by the disappearance of glycogen; a possible reduction of the water content could be excluded. The small increase in total liver protein, which was another finding, is attributable to a nonspecific stimulation of protein synthesis. The observed quantitative changes in the liver substance required balancing of the food ingested: following 8-hr inhalation of 100 or 400 ppm there was a marked reduction in body weight, intake of standard food and water, and fecal excretion, whereas slight increases were observed after 20 ppm over 8 hrs. These alterations are probably due to a disturbance of the diencephalic controlling mechanisms.Presented in part at the 10th Spring Meeting of the Deutsche Pharmakologische Gesellschaft, Mainz, March 16 – 19, 1969.     

二硫化碳职业接触对心血管系统的影响

目的探讨高浓度二硫化碳(CS2)接触对心血管系统的影响。方法查阅10年来车间空气中CS2的浓度;对120名已被确诊为"职业性慢性轻度CS2中毒"的患者进行了血压、血脂、心血管系统的调查。结果空气中CS2浓度常年均超过国家卫生标准的最高容许浓度(10 mg/m3);高血压、高血脂(三酰甘油、载脂蛋白B)、心电图异常的发生率病例组非常显著地高于对照组。结论长期高浓度CS接触对心血管系统可产生影响。     

Occupational exposure to carbon monoxide and sulphur dioxide during the manufacture of carbon black.

The manufacture of carbon black is known to generate carbon monoxide and sulphur dioxide in the 'production gas' and the pyrolysis products of the 'production gas', respectively. Adverse health effects have been reported as associated with both contaminants (coronary heart disease with carbon monoxide and respiratory morbidity with sulphur dioxide). A major cross-sectional and longitudinal respiratory morbidity study is being conducted to assess the effects of exposure to carbon black on lung function, on chest X-rays and on responses to a questionnaire. The questionnaire includes questions on respiratory and cardiovascular symptoms, so that information regarding confounding exposure is essential. The working population of 18 manufacturing plants in seven European Countries was split into 13 job title numbers (1-13) which were then amalgamated into five job categories (A-E), with an appropriate (statistically) number of samples taken from each plant-job category. In total, 1322 carbon monoxide samples and 1301 sulphur dioxide samples were taken, using actively pumped longterm colorimetric tubes. In the majority of cases, more than half of the samples in each plant-job category were either zero or trace, thereby preventing the accurate estimation of the average exposure. The highest median carbon monoxide concentration was from the amalgamated data from all 18 plants in job number 9 (furnace operators), the highest median sulphur dioxide concentration was only 'trace'. The large number of zero and trace values also precluded the generation of current and retrospective exposure indices.     

Blood concentrations of carbon disulphide in dithiocarbamate exposure and in the general population

Summary Blood carbon disulphide (CS₂), both free and total, was determined by gas chromatography-mass spectrometry in 112 normal subjects and in 20 subjects employed in a dithiocarbamate factory, comprising ten blue-collar workers involved in dithiocarbamate production and ten white-collar office staff. The ten production workers were examined over two workshifts, the first at the beginning of the week (Monday) and the second after an intervening period of at least 1 day. Three blood samples were taken for each shift studied, one prior to starting work, one at the end of the shift and the third 16 h after the end of the shift (on the following morning). The mean CS₂ blood levels measured in the 112 normal subjects was 663 ng/l for the free fraction and 3178 ng/l for the total. In 16 blood samples taken from the ten dithiocarbamate factory office workers, the mean free and total CS₂ blood levels were 846 and 4140 ng/l, respectively, i.e. not significantly different from those observed in the normal subjects. At the end of the first 8-h shift, the ten dithiocarbamate factory production workers had free and total CS₂ values of 1070 and 8471 ng/l, respectively, which were significantly higher than those observed prior to starting work (240 and 4738 ng/l). All the total CS₂ levels measured in the shop-floor workers, with the sole exception of the values recorded prior to the start of the Monday shift (4738 ng/l), ranged from 7047 to 8471 ng/l and were significantly higher than those measured in the white-collar staff (4140 ng/l).     

Biological monitoring of carbon disulphide and phthalate exposure in the contemporary rubber industry

Objectives: We studied the range in urinary levels of 2-thiothiazolidine-4-carboxyl acid (TTCA), a metabolite of CS₂ and phthalic acid (PA), a common metabolite of phthalates, across factories and departments in the contemporary rubber manufacturing industry. Methods: Spot urine samples from 101 rubber workers employed in nine different factories were collected on Sunday and during the workweek on Tuesday, Wednesday and Thursday at ∼4 pm. In total, 386 urine samples were successfully analyzed. Results: Levels of both biomarkers increased significantly by a factor 2 (paired t-test P-value <0.05) during the working week as compared to the Sunday biomarker levels with absolute increases of approximately 70 μg/l and 5 μmol/mol creatinine for PA and TTCA, respectively. Levels in both biomarkers did not differ markedly between working days. Increases seemed to be restricted to specific factories and/or departments (e.g. molding and curing). Conclusions: The results of this study demonstrate that rubber workers in the contemporary rubber industry are exposed to phthalates and low levels of CS₂ (∼0.05 ppm) as measured by PA and TTCA, respectively. Exposures to both compounds are largely driven by specific circumstances in factories. Therefore, when estimating exposures to phthalates and CS₂ detailed information should be collected on the type and amount of phthalate containing ester plasticizers, dithiocarbamates and thiurams used. Preferably, personal exposure data should be collected. In this case, biological monitoring seems a reasonable approach. However, in the case of PA attention should be given to individual background levels as this could lead to a substantial overestimation of the occupational contribution to total phthalate exposure.     

Effect of carbon disulphide intoxication on fecal excretion of end products of cholesterol metabolism

Summary The aim of this study was to compare the time course of ¹⁴C-steroid excretion following administration of ¹⁴C-cholesterol in normal and CS₂intoxicated rats. The excretion of steroid with the feces was evaluated in the normal and CS₂ intoxicated rats at the end of 7 month exposure to CS₂. The results of the experiment indicated that in rats exposed to CS₂ excretion of ¹⁴C-steroid is lower. It was due to a reduced excretion of ¹⁴C-bile acid fraction while at the same time the share of sterol + rose. On the basis of our former results which excluded the influence of CS₂ on absorption of cholesterol and indicated its effect on cholesterol synthesis it was revealed in this experiment that intoxication with CS₂ also inhibits cholesterol degradation. Disturbances of both processes can be essential for accumulation of cholesterol in blood of animals intoxicated with CS₂.This investigation has been carried out under the Polish-American agreement No. 05-008-2 with the Occupational Health Program, U.S. Public Health Service     

Relation between the iodine azide test and the TTCA test for exposure to carbon disulphide

Exposure to carbon disulphide (CS2) in a viscose plant was measured by personal monitoring and by application of the iodine azide test and quantification of 2-thio-thiazolidine-4-carboxylic-acid (TTCA) in urine samples. A relation was found between the rise in urinary TTCA concentration during the workshift and the exposure index E1. The correlation (r) between the exposure index and the atmospheric concentrations of CS2 in workroom air below 100 mg CS2/m3 was 0.59 (n = 9). The correlation between the increase in TTCA concentrations during the workshift and the atmospheric CS2 concentrations was found to be higher when urine samples at the end of the workshift with creatinine concentrations below 1 mg/ml and above 3 mg/ml were disregarded (from r = 0.61; n = 20 to r = 0.84; n = 14). A high correlation was found (r = 0.86; n = 13) when the end of workshift urine samples were analysed, provided that their creatinine concentrations are not beyond the limits given above.     

Evaluation of occupational exposure to carbon disulphide by blood, exhaled air, and urine analysis

This paper compares three analytical methods that may be considered for monitoring workers who are exposed to carbon disulphide (CS2). An estimate of the uptake of CS2 was assessed by the measurement of "bound" CS2 in blood, CS2 in expired alveolar air, and 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. The concentration of TTCA in end-of-shift urine samples was related to exposure and appears to be a good measure of uptake of CS2.     

Special nerve functions and colour discrimination in workers with long term low level exposure to carbon disulphide

Certain functions of the peripheral and autonomic nervous systems, and colour discrimination were examined in 45 workers (mean age 49; mean exposure to carbon disulphide (CS2) 20 years) and 37 controls (mean age 48). Conduction velocity and refractory period of the peroneal and sural nerves were determined. The conduction velocity of the slower fibres of the peroneal nerve was measured by means of an improved method that makes use of the refractory period. Function of autonomic nerves was assessed by measuring the variation in heart rate during rest, during deep breathing, and during isometric muscle contraction. Colour discrimination was evaluated by the Lanthony desaturated test. Individual cumulative exposure to CS2 was calculated on the basis of exposure in the past and individual job history. Mean cumulative exposure was 165 ppm-years. The peroneal nerves of exposed workers showed a decrease (-1.0 m/s) in conduction velocity of the slow fibres and a prolongation (0.1 ms) of the refractory period (mean 1.6 ms) compared with controls. These effects were related to cumulative exposure. No impairment of function of the sural nerve or of colour discrimination was found. The muscle heart reflex was decreased in the exposed group, but this was not related to cumulative exposure. This study has established more firmly that a decrease in conduction velocity of slow motor fibres occurs at low levels of exposure to CS2. Extrapolation of the results suggests that small effects may occur after 40 years of exposure to concentrations below the present threshold limit value (10 ppm).     

Relation between the iodine azide test and the TTCA test for exposure to carbon disulphide.

Exposure to carbon disulphide (CS2) in a viscose plant was measured by personal monitoring and by application of the iodine azide test and quantification of 2-thio-thiazolidine-4-carboxylic-acid (TTCA) in urine samples. A relation was found between the rise in urinary TTCA concentration during the workshift and the exposure index E1. The correlation (r) between the exposure index and the atmospheric concentrations of CS2 in workroom air below 100 mg CS2/m3 was 0.59 (n = 9). The correlation between the increase in TTCA concentrations during the workshift and the atmospheric CS2 concentrations was found to be higher when urine samples at the end of the workshift with creatinine concentrations below 1 mg/ml and above 3 mg/ml were disregarded (from r = 0.61; n = 20 to r = 0.84; n = 14). A high correlation was found (r = 0.86; n = 13) when the end of workshift urine samples were analysed, provided that their creatinine concentrations are not beyond the limits given above.