[Detection rate analysis on neurological sign of workers exposed to different concentrations of carbon disulfide]

OBJECTIVE

To study the effects of exposed to different concentrations of carbon disulfide on neurological signs of workers.

METHODS

Collection the information of concentration of carbon disulfide in the workplace or workers individuals exposed of a chemical fiber industry from 2004 to 2011, a total of 3 537 workers exposed to carbon disulfide were detected muscle strength and muscle tone, knee reflex, Achilles tendon reflex, trembling limbs, sensory function, and three chatter. Chi-square test was used for statistical analysis on abnormal neurological signs of workers.

RESULTS

Eight hours time-weighted average concentration range of workers exposed to carbon disulfide in this chemical fiber industry was 0.2-41.0 mg/m(3), geometric mean was 2.38 mg/m(3). Concentration of carbon disulfide exposure of 1 771 workers was from 0.2 to 2.5 mg/m3( ≤ 2.5 mg/m(3)), 642 workers was 2.6-4.8 mg/m(3) (< 5.0 mg/m(3)), other 1 051 workers was from 5.1 to 41.0 mg/m(3) ( > 5.0 mg/m(3)) in all subjects. The different detection rates of knee reflex were 3.0% (31/1 045), 3.7% (21/574), 4.8% (16/331), 3.3% (10/305), 5.9% (11/187), 6.7% (68/1 022), the different detection rates of Achilles tendon reflex were 2.2% (23/1 045), 3.7% (21/574), 2.7% (9/331), 2.3% (7/305), 2.1% (4/187), 5.6% (57/1 022), the different detection rates of sensory dysfunction were 0.4% (4/1 045), 0.5% (3/574), 0.6% (2/331), 0.0% (0/305), 2.1% (4/187), 1.7% (17/1 022) in different cumulative amount of contact groups ( ≤ 10.0, 10.1-20.0, 20.1-30.0, 30.1-40.0, 40.1-50.0, >50.0 mg/m(3) per year), and the differences were statistically significant (χ(2) = 19.53, 21.27 and 15.89, all P values were <0.01) . Stratified according to age and gender, in addition to the ≤ 25 years group the difference of detection rate analysis on Achilles tendon reflex was statistically significant in the different concentration group (the ratio of on Achilles tendon reflex in the different groups of concentration of carbon disulfide exposure of 2.5, 2.6-5.0, ≥ 5.0 mg/m(3) were 0.4% (2/511), 1.0% (1/98), 2.1% (7/327), χ(2) = 5.59, P = 0.045) , the difference of detection rate analysis on neurological sign was not statistically significant in the different concentration group on the rest of the age and gender groups (P > 0.05).

CONCLUSION

Within the concentration range of the object of study contact actual, different concentrations of carbon disulfide in addition to individual neurological signs of individual ages influential, it has no significant effect on the various signs of nervous system of workers of most age and gender groups, expect the age below the 25 years old group.

Coronary artery disease and cancer mortality in a cohort of workers exposed to vinyl chloride, carbon disulfide, rotating shift work, and o-toluidine at a chemical manufacturing plant

BACKGROUND

We updated through 2007 the mortality experience of 1,874 workers employed at a New York State chemical manufacturing plant between 1946 and 2006.

METHODS

Reassessed exposures to vinyl chloride, carbon disulfide, and shift work and categories of o-toluidine exposure were based on year, department and job title. Standardized mortality ratios (SMR) compared mortality to that of the US population. Internal comparisons used directly standardized rate ratios.

RESULTS

Hepatobiliary cancer mortality was elevated among workers ever exposed to vinyl chloride (SMR = 3.80, 95% confidence interval 1.89-6.80); directly standardized rates increased with increasing vinyl chloride exposure duration. No increase in non-Hodgkin lymphoma mortality was observed with vinyl chloride and shift work exposures. Internal comparisons showed increased coronary artery disease mortality among long-term workers exposed to carbon disulfide and shift work for 4 years or more.

CONCLUSIONS

Excess coronary artery disease mortality confirms earlier results; further investigation is needed to understand risk factors.

[Effect of carbon disulfide exposure during peri-implantation period on levels of calcitonin and progesterone in uterus of mice]

OBJECTIVE

To evaluate the effect of carbon disulfide (CS2) exposure during the peri-implantation period on the levels of calcitonin (CT) and progesterone (P4) in the uterus of pregnant mice and to investigate the mechanism of embryo loss induced by CS2 exposure during the peri-implantation period.

METHODS

A total of 168 healthy pregnant Kunming mice were randomly assigned to receive an intraperitoneal injection of CS2 (631.4 mg/kg) or olive oil (control) on gestational day (GD) 3, GD4, GD5, or GD6. The experiment was completed at different end points (GD4, GD5, GD6, GD7, and GD9). The levels of CT and P4 in the uterus were measured by enzyme-linked immunosorbent assay at each end point.

RESULTS

The numbers of implanted embryos in GD3, GD4, GD5, and GD6 exposure groups significantly decreased by 42.85%, 63.74%, 60.45%, and 47.26%, respectively,compared with those in control group (P < 0.01). The GD3, GD4, GD5, and GD6 exposure groups had significantly decreased CT levels at each end point (P < 0.05), and the GD3, GD4, and GD5 exposure groups had significantly decreased P4 levels (P < 0.05). In the GD3, GD4, GD5, and GD6 exposure groups, the number of implanted embryos was positively related with the levels of CT and P4 expressed in the uterus (r = 0.670, P < 0.01; r = 0.632, P < 0.01); the expression level of CT was positively related with that of P4 in the uterus of pregnant mice (r = 0.325, P < 0.01).

CONCLUSION

Exposure to CS2 during the peri-implantation period can reduce the expression levels of CT and P4 in the uterus of pregnant mice, which might be one of the molecular mechanisms of embryo loss induced by CS2 exposure.

[Studing the health status of workers occupationally exposed to carbon disulfide]

OBJECTIVE

To study the effects of carbon disulfide (CS(2)) on the health of workers, and to provide the basis for the further preventive measures.

METHODS

The occupational health examination of 881 workers exposed to CS(2) in a chemical fiber factory was carried out according to the national technical standard of occupational health surveillance. The time weighted average concentrations (TWA) of CS(2) in the workshops of short silk and long silk exceeded the national standard, The workers in these two workshops served as the high exposure group. The workers of the other workshops were classified as low exposure group, in which TWA met the national standard. All exposed workers were also divided into long-term exposure group and short-term exposure group on the basis of average exposure years (16 years). The statistical analysis was used by t test, χ(2), and fisher exact test.

RESULTS

The symptom rates of numbness, fatigue, dizziness, insomnia and headache were 12.5%, 8.5%, 8.2%, 7.5%, and 7.2% respectively. The abnormal rates of superficial sensation, three fibrillation, achilles tendon reflex, patellar reflex, EMG, hypertension, triglycerides, low-density lipoprotein, and apolipoprotein B were 33.0%, 26.1%, 20.8%, 18.6%, 10.8%, 33.4%, 24.5%, 17.0% and 9.3% respectively. Among the high exposure group, the abnormal detectable rates of dizziness, headache, fatigue, insomnia, numbness, achilles tendon reflex, superficial and deep sensation, EMG, hypertension, ECG, total cholesterol, triglyceride and low density lipoprotein in long-term exposure group were significantly higher than those in short-term exposure group (P < 0.05 or P < 0.01). However, among the low exposure group, the abnormal rates of the insomnia achilles tendon reflex and superficial sensation in long term exposure group were significantly higher than those of short term exposure group (P < 0.05 or P < 0.01). The detected rates of hypertension, triglycerides, low-density lipoprotein, creatinine and uric acid were in males significantly greater than those in females (P < 0.05 or P < 0.01).

CONCLUSION

Long-term exposure to high concentrations of CS(2) could lead to the damage of nervous system, elevate blood pressure and promote the development and progression of hyperlipemia and atherosclerosis. Furthermore, CS(2) had greater effects on blood pressure and lipid in males than in females.

[Effects of carbon disulfide on cardiovascular system of workers occupationally exposed to carbon disulfide]

OBJECTIVE

To study the effects of long-term exposure to carbon disulfide (SC(2)) on cardiovascular system of workers.

METHODS

The concentrations of CS(2) were detected in the representative workshops with different exposure levels. The indicators related to cardiovascular system were tested in 633 workers occupationally exposed to CS(2), which included blood pressure, electrocardiogram, blood routine (blood RT), cholesterol (TCHO), triglyceride (TG) and so on. The data were analyzed by chi-square test and multiple logistic regression analysis.

RESULTS

The exposure concentration of CS(2) for 389 workers was less than or equal to 5 mg/m(3), which for other 244 workers was higher than 5 mg/m(3). The maximum exposure concentration of CS(2) was 15.73 mg/m(3). There were no significant effects of CS(2) on the electrocardiogram, red blood cells, white blood cells, blood platelet, TCHO and TG of workers. However, the positive effects of CS(2) on blood pressure and negative effects of CS(2) on hemoglobin were found. The rates of high TCHO, TG and hypertension in male workers were significantly higher than those in female workers (P < 0.05). The rates of high TCHO, hypertension and sinus arrhythmia in older workers (≤ 30 years old) were significantly higher than those in young workers (> 30 years old) (P < 0.05). The rate of sinus arrhythmia in workers with 1 - 10 working years was significantly higher than that in workers with more than 10 working years (P < 0.05). The rate of hypertension in workers with 1 - 10 working years was significantly lower than that in workers with more than 10 working years (P < 0.05).

CONCLUSION

There were no significant effects of CS(2) exposure on the indexes of cardiovascular system of workers.

Cancer Mortality and Solvent Exposures in the Rubber Industry

Some evidence suggests that solvent exposures to rubber industry workers may be associated with excess cancer mortality, but most studies of rubber workers lack information about specific chemical exposures. In one large rubber and tire-manufacturing plant, however, historical documents allowed a classification of jobs based on potential exposures to all solvents that were authorized for use in the plant. A case-control analysis of a 6678 member cohort compared the solvent exposure histories of a 20% age-stratified random sample of the cohort with those of cohort members who died during 1964-1973 from stomach cancer, respiratory system cancer, prostate cancer, lymphosarcoma, or lymphatic leukemia. Of these cancers, only lymphosarcoma and lymphatic leukemia showed significant positive associations with any of the potential solvent exposures. Lymphatic leukemia was especially strongly related to carbon tetrachloride (OR = 15.3, p less than .0001) and carbon disulfide (OR = 8.9, p = .0003). Lymphosarcoma showed similar, but weaker, associations with these two solvents. Benzene, a suspected carcinogen, was not significantly associated with any of the cancers.

[Effect of CS(2) occupational exposure on personality and intelligence]

OBJECTIVE

To investigate the effects of CS(2) occupational exposure on thumbprint and intelligence.

METHODS

According to the monitoring results of CS(2) concentration, which were got at various workplace in chymic fiber factory, the workers were divided into three groups including the low-concentration group (TWA < 5 mg/m(3)), the high-concentration group (TWA >or= 5 mg/m(3)) and the control group. The method of cluster sampling was used respectively. 139, 129 and 327 people were taken at random from three groups and they were given thumbprint and intelligence examinations through following three methods, including MMPI, SCL-90 and SPM.

RESULTS

MMPI test showed that Hy, Pa, Pt, Sc positive rates in the low-concentration group were 7.19%, 2.16%, 26.62% and 10.07%, Hs, D, Hy, Pa, Pt, Sc, Ma, Si positive rates in the high-concentration group were 32.56%, 8.53%, 9.30%, 24.81%, 2.33%, 42.64%, 15.50%, 5.43% and 6.20%. There was a significant difference with the control group (Hs, D, Hy, Pd, Pa, Pt, Sc, Ma, Si was 14.07%, 2.14%, 2.14%, 14.07%, 0.00%, 17.74%, 3.67%, 1.22%, 1.22% respectively). The differences of Hs, Pt positive rates between high-concentration and low-concentration group were significantly. SCL-90 showed that the total positive rate in the low concentration and the high concentration groups was 15.8% and 20.2%. The positive rate of the basic factors were significantly different among the low-concentration group, the high concentration group and the control group while there was no significant difference in the positive rate between the high concentration and low concentration group. SPM test found that the positive rates of the intelligence in the low concentration group and the high concentration group were 35.1% and 35.7% respectively and the control group (15.1%) was significantly different from low-concentration and high concentration group. Moreover, there was no obvious difference between high-concentration and the low-concentration group. The intelligence damage was associated with the length of CS(2) occupational exposure and the correlation coefficient had statistical significance.

CONCLUSION

The low-concentration CS(2) occupational exposure could affect personality and intelligence, and the degree of this influence is associated with the length of CS(2) occupational exposure.

[Effects of carbon disulfide on blood pressure and electrocardiogram for workers exposed to levels below the national maximum allowable concentration]

OBJECTIVE

To study the effects of carbon disulfide exposure within the national maximum allowable concentration(MAC) on blood pressure and electrocardiogram, and associations with selected factors.

METHODS

Workers in a chemical fiber factory were divided into two groups based on the type of work: a high exposure group (HEG) of 821 individuals and a low exposure group (LEG) of 259. The CS2 concentration at workplace was controlled under the national MAC. A set of 250 randomly selected people taking routine physical check-ups in the same period and hospital constituted the control group. The systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured on the arm, and the pulse pressure (PP) and mean arterial blood pressure (MABP) were calculated based on SBP and DBP. The blood pressure data, along with the results of the routine 12-lead electrocardiography taken at rest and records on gender, age, years of work, type of work, and concentrations of triglycerol, cholesterol, and glucose in blood, were compiled for analyses. Risk factors upon CS2 exposure for the increase of blood pressure and occurrence of electrocardiogram abnormalities were identified and rationalized.

RESULTS

Significant difference (P < 0.01) in the average values of SBP, DBP, MABP, and the corresponding abnormality incident rates was found between HEG and LEG, and between HEG and the control group. For both HEG and LEG, the incident rate of DBP abnormality (high DBP) is nearly two times as high as that of SBP. Type of work is the largest risk factor in both the high SBP and high DBP subgroups, with odds ratios (OR) of 2.086 and 2.331 respectively, and high CS2 exposure presents more than double the risk than low exposure. On the incident rate of ECG abnormalities, both exposure groups are significantly different (P < 0.01) to the control group. High SBP in LEG and high DBP in HEG were found to be significant risk factors (OR = 3.531 and 1.638 respectively), while blood glucose appears to be a protective factor (OR = 0.747), appealing to further investigation. Meanwhile, factors like years of work and cholesterol were found to be risk factors in the high SBP subgroup with low exposure, and in the high DBP subgroup with high exposure. Within HEG, high DBP is the only blood pressure-related risk factor found for the incident of left ventricular high voltage (OR = 4.140), as is high SBP for LEG (OR = 4.776). High PP is the only risk factor found for repolarization disturbances within LEG (OR = 20.417). While blood sugar is a risk factor for origin disturbances, it is a protection factor for left ventricular high voltage (OR = 0.633).

CONCLUSION

The damage of CS2 done to the cardiovascular system is a gradual process. Both early and very low level exposures are detrimental to the human circulatory system. Below the National MAC limit, the toxic effect of CS2 to the cardiovascular system increases with time and level of exposure. The effect of CS2 on DBP is more significant than on SBP, which indicates that CS2 may affect peripheral resistant blood vessels more than the artery. The abnormalities of ECG of workers exposed to CS2 are not only the result of high blood pressure on the heart, but also of the direct toxicity of CS2 on heart and blood vessels.

Organic solvents and hearing loss: The challenge for audiology

Organic solvents have been reported to adversely affect human health, including hearing health. Animal models have demonstrated that solvents may induce auditory damage, especially to the outer hair cells. Research on workers exposed to solvents has suggested that these chemicals may also induce auditory damage through effects on the central auditory pathways. Studies conducted with both animals and humans demonstrate that the hearing frequencies affected by solvent exposure are different to those affected by noise, and that solvents may interact synergistically with noise. The present article aims to review the contemporary literature of solvent-induced hearing loss, and consider the implications of solvent-induced auditory damage for clinical audiologists. Possible audiological tests that may be used when auditory damage due to solvent exposure is suspected are discussed.

[Validity of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) as biomarker of exposure to very low concentrations of carbon disulphide: preliminary results]

The possibility to use urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) as biomarker of occupational exposure to very low doses of carbon disulphide (CS2) was evaluated preliminarily in 10 workers employed in a chemical plant where rubber vulcanization accelerators are produced, and in 10 workers, residents in the same geographical area and not occupationally exposed to CS2 and dithiocarbamates (DTC). Exposure to airborne CS2 was assessed, only for exposed workers, by both personal and area samplers. For the determination of TTCA, a spot urine sample was collected for each worker, exposed and non exposed, at the end of work-shift. A questionnaire probing lifestyle and dietary habits and non occupational exposure to CS2 and DTC was administered to all workers involved in the study. Environmental exposure to CS2 in 2007 ranged between 0.21 mg/m3 and 0.73 mg/m3 for personal sampling, and between 0.23 mg/m3 and 0.41 mg/m3 for area sampling. Urinary TTCA levels resulted very low and did not show any significant difference between exposed (Median: 10.8 microg/g creat; Range: 6.1-26.4 microg/g creat) and non exposed workers (Median: 9.3 microg/g creat; Range: 3.0-33.0 microg/g creat), while higher, but not significant concentrations of TTCA were observed in smokers than in non smokers (p = 0.09). No correlation was found between urinary TTCA levels and environmental exposure to CS2, age, body mass index, smoking and dietary habits. In conclusion, the low sensibility and specificity in the assessment of occupational exposure to low doses of CS2 in workers compared to general population subjects, makes urinary TTCA a biomarker with a low usefulness in biological monitoring. ACGIH, besides, should also introduce "B" (background) notation, at present not considered for the BEI indicated for urinary TTCA.

Evidence for oxidative stress at elevated plasma thiol levels in chronic exposure to carbon disulfide (CS2) and coronary heart disease

OBJECTIVES

Oxidative stress in plasma may be promoted by plasma thiols such as homocysteine. However, other thiols such as glutathione may also exert antioxidant effects in vitro and in vivo. To further investigate whether plasma thiols act as prooxidants or antioxidants, we compared plasma oxidative status in patients with coronary heart disease (CHD) and in subjects occupationally exposed to carbon disulfide (CS(2)).

METHODS

Fifty-five subjects chronically exposed to CS(2), 53 CHD patients, and 52 healthy controls were examined. To assess plasma oxidative status, concentrations of thiobarbituric reactive substances (TBARS) and total antioxidative capacity (TAC), as well as ferritin and ceruloplasmin were determined. Antioxidative reserve was assessed by the determination of vitamine E, uric acid, superoxide dismutase, catalase, and glutathion peroxidase. In addition, protein and non-protein plasma thiol levels were measured.

RESULTS

Patients in both groups had increased levels of plasma thiols as compared to controls: CS(2)-exposed subjects presented with increased levels of thiols associated with plasma proteins, whereas CHD patients presented with elevated total homocysteine and cysteine levels. TBARS were significantly increased and TAC was significantly decreased both in CS(2)-exposed subjects and in CHD patients. In addition decreased activity of glutathione peroxidase, an antioxidative enzyme inhibited by thiol-containing compounds, was noted in both groups.

CONCLUSION

These results demonstrate that regardless of their metabolic origin increased thiols are associated with increased oxidative stress in plasma.

Risk for hypertension in workers exposed to carbon disulfide in the viscose rayon industry

BACKGROUND

Chronic exposure to carbon disulfide (CS(2)) has been associated with hypertension, elevated cholesterol, arteriosclerosis, ischemic heart disease and related mortality, adverse nervous and reproductive health effects, and hearing impairment. This study assessed the hypertension risk for male rayon workers exposed to CS(2).

METHODS

A total of 251 rayon workers and 226 administrative clerks at two plants in Taiwan received health examination and interviews, and were compared for hypertension risk. On-site CS(2) levels were measured.

RESULTS

The hypertension was more prevalent in the exposure group (43.4%) than in controls (7.1%) with greater impact on systolic blood pressure than diastolic. Multivariate logistic regression analysis showed a significant dose-response relationship between hypertensive risk and cumulative exposure index (CEI) with an odds ratio of 15.1 for workers exposed to 343-468 year-ppm of CS(2). The overall risk was elevated to 7.6 times higher for rayon workers. The risk increased significantly after more than 10 years of employment.

CONCLUSIONS

This study suggests that it takes a long exposure period to develop hypertension for rayon workers with CS(2) exposure.

Electrocardiographic features of Korean carbon disulfide poisoned subjects after discontinuation of exposure

OBJECTIVE

Mass poisoning by carbon disulfide (CS(2)) was reported at a viscose rayon factory in Korea in the late 1980s; the factory was subsequently closed in 1993. In this study, we evaluated the late electrocardiographic features in the CS(2) poisoned subjects.

METHODS

The cases were composed of 198 retired workers with a history of CS(2) poisoning. An age- and sex-matched reference group was randomly selected from people visiting a hospital for regular health checkups. Intervals, amplitudes and abnormal findings from the electrocardiograms (ECGs) of the two groups were compared.

RESULTS

Except for the PQ interval, there were no significant ECG differences between the two groups. The cases exhibited ECG abnormalities more frequently than the reference group. Multiple logistic regression analysis revealed that CS(2) poisoning was positively associated with the presence of abnormal ECG findings (OR = 1.603; 95% CI, 1.008-2.549).

CONCLUSION

This study suggests that CS(2) poisoned subjects may have an increased risk of ECG abnormalities even after the exposure to CS(2) is no longer present.

Carbon disulfide encephalopathy: cerebral microangiopathy

To understand cerebral blood circulation after long-term exposure to carbon disulfide (CS2), four patients with encephalopathy and polyneuropathy, who had worked in a viscose rayon plant, were studied. Clinical and laboratory examinations, including brain magnetic resonance images (MRI), computed tomography (CT), CT perfusion, and CT angiography, were carried out. Brain CT and MRI disclosed mild cortical atrophy in all four patients, and multiple lesions in the subcortical white matter, and basal ganglia in three patients. Brain CT angiography and perfusion revealed a statistically significant decrease of cerebral blood flow (CBF) in the total brain parenchyma and basal ganglia, and a decrease of the cerebral blood volume (CBV) in the basal ganglia and a prolonged mean transit time (MTT) in the total brain parenchyma, and the territories of the internal carotid artery (ICA), basal ganglia and occipital lobe. In conclusion, the decrease of CBV and CBF, and the prolonged MTT in the total brain parenchyma, ICA, basal ganglia and occipital lobes, indicated a microangiopathy in patients with CS2 encephalopathy.

[Interactions between solvents and noise: state of the art]

There are several environmental and occupational scenes where a co-exposure of noise and solvents occurs, therefore between a neurotoxic and a ototoxic agent. Epidemiological and experimental studies with simultaneous exposure to noise and solvents like toluene, styrene and carbon disulfide have been analysed. These studies investigate possible ototoxic effects through audiometry, auditory brainstem response, potential recall and reflex decay test. The current available data show that with high exposure levels, that are responsible for tissue damage by themselves, the interaction between noise and solvents could occur. The present knowledge can not permit a conclusion for low exposure levels.

Cardiovascular function of workers exposed to carbon disulphide

OBJECTIVES

The aim of the study was to verify that exposure to carbon disulphide (CS(2)) up to 10 ppm results in a negative inotropic effect on cardiovascular function.

METHODS

In a cross-sectional study a total of 325 workers exposed to CS(2) in the rayon-producing industry and 179 controls from the same plants were examined. The exposure assessment was based on personal air sampling and biological monitoring (2-thiothiazolidine-4-carboxylic acid (TTCA) in urine) for all persons. The examination consisted of a standardised questionnaire, physical examination, assessment of body fat mass, ergometric test with the determination of work capacity at heart rates of 100, 130, 150 and 170 beats/min, and electrocardiography.

RESULTS

The mean external exposure was 6.04 ppm CS(2) (range: 0.03-91.08); the mean internal exposure was 1.14 mg TTCA/g creatinine (range: 0.02-11.50). The workers exposed to CS(2) showed better physical fitness. The diameters of the left heart chamber of the exposed persons were not significantly different when compared with occupationally non-exposed workers, but there was a tendency of increasing diameters for the exposed employees. In the multiple linear regression the diameters showed physiologically plausible correlations with the body mass index, body fat mass, alcohol consumption, and physical fitness, but not, however, with the exposure, neither with the exposure group in all persons nor with the internal or external exposure within the exposed workers.

CONCLUSIONS

In this study, differences in the heart chamber diameters between exposed persons and controls could not be confirmed. Differences in physical fitness and constitution can explain differences in heart chamber diameters.

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.

Critical review of the epidemiological literature on the potential cardiovascular effects of occupational carbon disulfide exposure

OBJECTIVES

Occupational carbon disulfide (CS(2)) exposure has been associated with a variety of health effects since its introduction in the mid-19th century. Much of the epidemiological interest, especially since the 1960s, has focused on associations with cardiac effects. However, considerable differences in study approach, disease outcome, CS(2) exposure level, and control of confounding factors have produced mixed results and conclusions. This critical review presents a synthesis of the most relevant and best quality studies to better understand these associations.

METHODS

Using specific criteria to assess methodological and scientific quality, we identified 37 studies with the potential to inform on at least one of the following questions: (1) Has a relationship between CS(2) exposure and coronary heart disease (CHD) mortality been reasonably demonstrated? If so, at what apparent exposure levels has it been observed? (2) Among studies of workers routinely exposed to CS(2) at levels greater than 20 ppm, have any health effects or indicators of CHD been observed consistently? (3) Among occupational groups exposed to CS(2) at levels less than 20 ppm, have any health effects or indicators of CHD been observed consistently?

RESULTS

Several CHD-related effects have been examined relative to various levels of occupational CS(2) exposure. Overall, there was remarkably little consistency of CHD effects observed, including CHD mortality.

CONCLUSIONS

Although a physiological effect of CS(2) exposure on CHD is plausible, the epidemiological evidence for an association between CS(2) exposure and various cardiac risk indicators is mixed. The only somewhat consistent finding, of CS(2) exposure on total and/or LDL cholesterol level, may be due to residual confounding by other time-dependent risk factors. If real, however, it appears to be of small magnitude and uncertain clinical importance.

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.

Increased oxidative stress in subjects exposed to carbon disulfide (CS2)--an occupational coronary risk factor

There is considerable epidemiological evidence that workers exposed to carbon disulfide (CS2) develop premature atherosclerosis leading to increased rates of coronary heart disease (CHD), but mechanisms underlying this association remain obscure. The present study documents that occupational exposure to CS2 modifies the oxidative status of plasma, which is a major determinant of the susceptibility to atherosclerosis. Concentrations of thiobarbituric reactive substances (TBARS), which reflect lipid peroxidation processes in plasma, were determined in 29 men who were exposed to CS2 for more than 20 years, in 24 patients with peripheral atherosclerosis, and in 30 unexposed, healthy control subjects. TBARS concentrations were significantly increased both in CS2-exposed subjects and in patients with peripheral atherosclerosis. Subjects in both groups presented also with decreased levels of plasma alpha-tocopherol, a major plasma antioxidant. In addition, decreased activities of two enzymatic antioxidants, glutathion peroxidase and catalase, were noted both in CS2-exposed subjects and patients with peripheral atherosclerosis. Finally, LDL isolated from both groups showed increased susceptibility to transition metal-induced oxidation in vitro. It is concluded, that occupational exposure to CS2 produces oxidative stress in plasma. This may favor the development of atherosclerosis and increase the incidence of CHD in workers exposed to CS2.

Mortality pattern in the cohort of workers exposed to carbon disulfide

The objective of the study was to assess mortality in the cohort of the viscose factory workers occupationally and environmentally exposed to carbon disulfide. Male workers employed for at least one year during 1950-1985 in the production or maintenance departments, living in the vicinity of the plant, were enrolled into the study. Of the 2,878 workers in the cohort, 2,762 were successfully traced, yielding 76,465 person-years. Mortality assessment was based on the standardized mortality ratio using a person-years method. The general male population of Poland was considered as a reference group. Total mortality in the cohort was higher than in the general male population in Poland (SMR = 108). A significantly increased risk of deaths was observed for all cardiovascular (SMR = 114) and cerebrovascular (SMR = 208) diseases. Analyses showed a significantly elevated risk of death from the circulatory system diseases in the men of the "highly exposed" group, spinners and those who were first employed before 1974. A statistically significant trend of mortality from all cardiovascular diseases in relation to the level of exposure (assessed qualitatively) was evident. No clear relationship between duration of exposure and the risk of death was found.

The cross-sectional study of the health effects of occupational exposure to carbon disulfide in a Chinese viscose plant

This article presents results of carbon disulfide exposure assessment in a Chinese viscose rayon factory and represents the cross-sectional study beginning phase of the occupational epidemiological project. The authors measured external exposure levels to carbon disulfide at a Chinese viscose rayon factory and monitored results as internal exposure indexes by testing urine samples of workers exposed to carbon disulfide levels. The rate at which carbon disulfide is metabolized by exposed subjects was demonstrated by 2-thio-thiazolidine-4-carboxylic acid (TTCA) concentrations in urine of exposed subjects, which was studied to determine best time points for internal exposure sampling. Carbon disulfide concentrations in the air of the workplace were analyzed with gas chromatography with flame photometric detector (GC-FPD); presence of TTCA in urine samples of subjects was determined using a modified high-performance liquid chromatography method. Kinetics of TTCA excretion was studied by analysis at different time points during and after exposure of workers to carbon disulfide. A total of 155 personal samples were obtained. Carbon disulfide concentration at staple viscose hall was found to be 13.72 +/- 1.12 mg/m3 in terms of geometric mean and geometric standard deviation. Carbon disulfide concentration at filament spinning hall was found to be 20.05 +/- 1.33 mg/m3. TTCA values of subjects at staple spinning hall were 1.18 +/- 0.43 and 1.07 +/- 0.38 mg/g creatinine for subjects working at filament spinning hall. The best time for TTCA sampling is at the end of the exposure-working shift.

Vascular changes in workers exposed to carbon disulfide

AIM

To assess the effects of occupational exposure to carbon disulfide (CS2) concentrations below the threshold limit value (31 mg/m3) on the structural and the functional properties of the arteries, heart rate, blood pressure and lipids.

METHODS

Study subjects were 85 male workers in the viscose industry and 35 men without such exposure. The CS2 concentration was determined by personal active sampling. From the common carotid artery diameter, the change in diameter (echography) during the heart cycle and the pulse pressure, local arterial distensibility and compliance were calculated. Global large and small artery elasticity were calculated from registrations of radial artery waveforms. Simultaneously, heart rate and blood pressure were recorded and blood samples were collected for lipid measurements.

RESULTS

CS2 concentrations ranged from 2.34 to 32.4 mg/m3. No significant effect of CS2 on blood pressure, total cholesterol, HDL and LDL cholesterol or triglycerides was found. Among the vascular parameters under study, common carotid artery distensibility was significantly lower, and heart rate significantly higher in exposed workers compared to controls. The differences remained significant after adjustment for age, body mass index, smoking habits, alcohol consumption, heart rate and systolic blood pressure. Common carotid artery intima media thickness and global arterial indices did not differ significantly between the two groups.

CONCLUSIONS

Exposure to CS2 under the current level may already cause alterations in common carotid artery elastic properties in apparently healthy individuals. Even before biochemical and clinical findings occur, important functional changes in the vessel wall were observed, at least in some vascular territories.

Carbon disulfide exposure assessment in a Chinese viscose filament plant

Carbon disulfide is a well-known occupational hazard in the viscose industry, and studies have shown considerable health effects when workers are exposed to high concentrations of this reagent. At exposure levels below the TLV-TWA(31 mg/m3), findings remain contradictory, probably due to deficient exposure data. The present study tries to identify the occupational hazards and thoroughly assess the exposure levels in a Chinese viscose rayon plant.

METHODS

An industrial hygienic field survey and a sampling campaign were carried out, including multi-gas monitoring, on-line measurements, and stationary assessment in the spinning hall as well as personal exposure sampling for spinners (by charcoal tube absorbing and GC-FPD analysis). All data was introduced into Foxpro database, and analyzed by Epi info (6.04) and SPSS.

RESULTS

On-line measurement showed that the geometric mean (GM) of carbon disulfide exposure amounted to 12.73 mg/m3 in 'exposure' and 0.08 mg/m3 in 'non-exposure' worksites. These concentrations in the air were related to the subject's activities showing the highest levels when they had to open the shield windows of the spinning machines. Stationary exposure measurements of carbon disulfide in the spinning hall amounted to 23.29 mg/m3 GM (range 5.8-97.94 mg/m3). Personal exposure of spinners was about 17.3 mg/m3 GM. Comparing these methods, the personal exposure sampling could exactly express the exposure levels of the worker's contacting situation. The on-line measurement by multi-gas monitor might also be recommended to the factory as it has its own advantages of rapid and independent assessment, but it under-estimates the exposure level.

Decreased carotid artery distensibility as a sign of early atherosclerosis in viscose rayon workers

Carbon disulphide (CS(2)) is known to accelerate atherosclerosis and to increase the risk for cardiovascular diseases. To assess the effect of CS(2) on the functional (distensibility and compliance) and the structural (intima media thickness) properties of the common carotid artery, and blood pressure and lipid metabolism parameters, a cross-sectional study on 85 workers from a viscose rayon factory and 37 controls was carried out. Exposure to CS(2) was assessed by personal monitoring and was well below the threshold limit value-time weighted average. Carotid arterial wall properties were determined using a non-invasive ultrasound wall movement detector system. No significant effect of CS(2) on blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol or triglycerides was found. Among the vascular parameters studied, only distensibility was significantly lower and heart rate was significantly higher in exposed subjects compared with the controls. In conclusion, occupational exposure to CS(2) may cause early alterations in arterial elastic properties in young individuals, and even before lipid and clinical findings have occurred, important functional changes in the vessel wall are present.

[Study on FM100-HUE color vision in male workers exposed to lower concentration of carbon disulfide]

The effect of CS2 on color vision in workers exposed to CS2 was explored. The color discrimination in 191 exposed and 93 non-exposed male workers was studied by a Farnsworth Munsell 100-HUE (FM100-HUE) test. The results showed that the time weighted average (TWA) concentration of CS2, determined by Japan GC-17A gas chromatography, was (14.75 +/- 6.89) mg/m3 in a long rayon workshop and (16.30 +/- 5.42) mg/m3 in a short rayon workshop. Higher FM100-HUE color vision score was often in the exposed group (106.9) than in the controls (78.3). The discrimination to green and blue zone was also significantly impaired (P < 0.05). It is concluded that the color vision was disturbed in workers exposed to CS2. The workers should be followed by health surveillance.

Cardiovascular disturbances in workers exposed to carbon disulfide

According to literature data myocardial infarction was often the first noticeable effect of CS2 on the cardiovascular system. Therefore, a question arises whether earlier circulatory lesions are absent in CS2-exposed people, or they are present but are not detectable by the diagnostic methods used. The aim of our study has been to determine whether electrocardiological disturbances do occur in exposed people, and their association, if any, with the level of CS2 exposure. Modern diagnostic methods (resting and 24-h ECG, heart rate variability, late ventricular potential analysis, and long-term blood pressure monitoring) were used to answer this question. The examination comprised 177 male workers aged 24-66 years (44+/-12), employed under conditions of the exposure for 5-38 years (14+/-9), and 93 male workers non-exposed to CS2 aged 23-65 years (41+/-12). Results of our studies show that abnormalities in resting and/or 24-h ECG recordings occur significantly more frequently in people exposed to CS2 than in the controls. ECG abnormalities were found primarily among the workers with a long, over 20-year, period of exposure. The considerable coincidence between the questionnaire and ECG results was found (87% reported complaints were confirmed by ECG data). Therefore it seems that all CS2-exposed people reporting heart symptoms should be subjected to a detailed examination. The frequency of late ventricular potentials in CS2-exposed people was not higher than in the controls. It may indicate that the ECG disturbances observed in those people were associated with functional rather than organic changes. Results of long-term ABP monitoring did not show increased incidence of elevated blood pressure in the exposed group. As the levels of the risk factors of ischemic heart disease in the exposed and control groups were similar, it seems that exposure to CS2 was responsible for the significant changes in the circulatory system.

Cardiovascular effects in viscose rayon workers exposed to carbon disulfide

The objectives of this study were to investigate the cardiovascular effects in workers currently exposed to carbon disulfide (CS2) below the threshold limit value (TLV) of 31 mg/m3 and to determine the prevalence of coronary heart disease (CHD) after long-term exposure. 172 men (91 workers exposed to CS2 in a viscose rayon factory and 81 referent workers) were examined using a medical and job history questionnaire, Rose's questionnaire, and electrocardiography at rest, and by measuring blood pressure and serum lipids and lipoproteins. Personal exposures were monitored simultaneously with active sampling and findings were analyzed according to the NIOSH 1600 method. As a result of technical and organizational improvements, personal CS2 exposures were well below the TLV (5.4-13.02 mg/m3). No significant effect of CS2 on blood pressure or lipids (total cholesterol, HDL and LDL cholesterol, triglycerides, and apolipoproteins AI and B) was found, even after allowance for confounding factors. The prevalence of CHD (ECG abnormalities and chest pain) was higher in the viscose rayon workers than in the workers with no exposure but reached statistical significance for men with exposure histories often years and more only (cumulative CS9 index > or = 150 mg/m3, the most highly exposed group). The findings suggest that the coronary risk is increased in workers previously exposed to high CS2 concentrations but not in those exposed to CS2 levels below the current TLV.

Occupational exposure to low concentrations of carbon disulfide as a risk factor for hypercholesterolaemia

OBJECTIVE

The objective of this study was to investigate the effect of occupational exposure to carbon disulfide (CS2) concentrations below threshold limit value (TLV)-time-weighted average (TWA) (31 mg/m3) on total cholesterol, blood pressure and the prevalence of coronary heart disease (CHD).

METHODS

A cross-sectional study involving 141 viscose rayon workers (64 men), and 141 age- and gender-matched controls without occupational contact with noxious chemicals, was carried out. The probability for CHD was determined by means of the WHO questionnaire and was 12-lead electrocardiography-coded using Minnesota criteria. Blood pressure was measured by the standardized method of the WHO and blood was examined for total cholesterol. A cumulative exposure index (CS2 index) was calculated for each worker by multiplying the number of years held in a particular job, by the CS2 concentrations in that job-environment. According to the CS2 index, the exposed workers were distributed into two groups: group 1 (CS2 index < 100) and group 2 (CS2 index > or = 100).

RESULTS

Depending on the job and specific work place the CS2 concentrations were between 1 and 30 mg/m3. Cholesterol levels were significantly higher in the exposed group (4.9 +/- 0.7) compared with the controls (4.6 +/- 0.7). Adjustment for age, smoking, body-mass index (BMI) and gender showed the significant effect of the CS2 index on the total cholesterol (P < 0.001). The prevalence of hypercholesterolaemia was significantly higher in the exposed group (42.6%), compared with the controls (26.2%); odds ratio (OR) (adjusted for potential confounders) was 2.56, 95% CI 1.47-4.46. Logistic regression showed a significantly increased risk for elevated cholesterol in group 2 (OR 5.52; 95% CI 2.81-10.83). No significant effect of CS2 index on blood pressure and CHD prevalence was found.

CONCLUSIONS

The results of our study show that occupational exposure to CS2 concentrations below 31 mg/m3 and a CS2 index > 100 may increase total cholesterol. Our results imply that even the CS2 concentrations below TLV-TWA may produce morbid changes, and suggest the mechanism of the effect of CS2, leading to lipid metabolism disturbances and acceleration of atherosclerosis.

[A preliminary study on body level of nitric oxide in workers exposed to carbon disulfide]

OBJECTIVE

To study changes in body plasma level of nitric oxide (NO) in workers exposed to carbon disulfide (CS(2)) and its possible mechanism.

METHODS

Plasma levels of NO and lipid peroxide (LPO) and activity of erythrocyte superoxide dismutase (Ery-SOD) were determined in the workers exposed and unexposed to CS(2) in a chemical synthetic fiber works.

RESULTS

Level of NO was (43.28 +/- 19.83) and (50.07 +/- 21.01) micromol/L in high- and low-dose exposed groups, respectively, significantly lower than that in the control group, which was (70.66 +/- 26.83) micromol/L (P < 0.05). Activity of Ery-SOD was 4 832.21 u/g Hb and 3,520.80 u/g Hb in high- and low-dose exposed groups, respectively, significantly higher than that in the control group, which was 2,425.34 u/g Hb (P < 0.05). Level of LPO was 19.38 and 17.09 micromol/L in high- and low-dose exposed groups, respectively, significantly higher than that in the control group, which was 4.37 micromol/L (P < 0.05).

CONCLUSION

Occupational long-term exposure to CS(2) could induce reduction of NO level in the body with its mechanism related to increase of super-oxygen cation O(2)(*-) induced by CS(2).

[Assessment of the hearing system in workers chronically exposed to carbon disulfide and noise]

Epidemiological studies carried out in the years 1984-1993 revealed carbon disulfide (CS2) to be one of the major chemical occupational hazards. Whereas among physical factors, noise was found to be the most common threat. Industrial workers very often face a combined exposure of two or more factors, like CS2 and noise, responsible for significant biological risk to the human health, although health effects of such an exposure have not as yet been thoroughly recognized and explored. The aim of this study was to assess changes in the hearing system in people exposed to toxic effect of CS2, recognized as characteristic of an overall clinical history of chronic poisoning by this solvent, in cases of concomitant exposure to noise exceeding maximum allowable levels. The study covered 80 workers aged 44-65 years (mean = 44.9 +/- 5.1), employed in a spinning mill of viscose fibre for 20.3 years on average (+/- 5.4 years) with clinically observed chronic CS2 poisoning, and a group of 40 people (mean age = 56.8 years) exposed to CS2 but without subjective or objective symptoms indicating chronic poisoning by the solvent. Both groups of subjects at similar age and with almost the same duration of employment were exposed to CS2 in concentrations changing in time between 10 and 35 mg/m3 (mean concentration = 25.8 mg/m3), and to continuous noise with the level ranging from 88 to 92 dB(A) for six hrs per one shift. The control group was composed of 40 workers (mean age = 52.0 +/- 5.3 years) employed in the cotton industry plant, without contact with CS2 or other chemicals and working in the acoustic environment with similar level of exposure to noise (86-93 dB(A)). Audiological and electronystagmographic examinations revealed bilateral retrocochlear hearing impairment associated with symptoms of the central vestibular syndrome in 97.5 subjects with diagnosed chronic CS2 poisoning. In workers free from clinical symptoms of chronic CS2 poisoning, perceptive hearing impairment of various degrees was found, including retrocochlear in 45% of subjects and cochlear in 32.5%, while in 22.5% of those under study normal hearing was observed. In the control group of subjects exposed to noise without contact with CS2, sensorineural cochlear hearing loss, typical of chronic acoustic trauma without concomitant vestibular disorders, was revealed. The results of the study show that in subjects with diagnosed chronic CS2 poisoning and exposed to noise, hearing impairment and vestibular disorders occur in the form of central changes which suggests a dominating CS2 toxic effect on the hearing system. But in some people exposed to both CS2 and noise, the hearing impairment in localised in cochlea like in acoustic trauma damage. This probably depends on individual susceptibility to harmful effect of these factors.

Antioxidative stress response in workers exposed to carbon disulfide

OBJECTIVE

To study the effects of carbon disulfide (CS2) on antioxidative stress systems of exposed workers.

METHODS

Enzyme-linked immunosorbent assay (ELISA) and thiobarbituric acid test (BAT) were conducted on 67 exposed workers and 88 controlled ones in a viscose rayon factory to determine their serum cuprozinc-superoxide dismutase (CuZnSOD) and malonyldialdehyde (MDA) levels.

RESULTS

The average levels of CuZnSOD in workers exposed to CS2 both above and below 10 mg/m3 were higher than those in the control group (P < 0.0001), showing some dose-effect and dose-response relationships. SOD levels increased when the exposure index (EI) was less than 300, and remained at a high level at the range of 300 to 900. When EI was higher than 900, SOD tended to decrease. Meanwhile, the serum MDA levels increased. Both CS2 concentrations and exposure time contribute to the MDA levels.

CONCLUSIONS

CS2 exposure could influence the stress response of the oxidative-antioxidative system of workers. Increased SOD levels could be considered as the stress response of antioxidative system to CS2 exposure in the early stages, and the influence of CS2 on SOD might be bi-directional. SOD and MDA might become objective indices in workers' health surveillance. The role of these two indices in the intoxication mechanism still needs to be clarified.

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 micromol/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 micromol/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.

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.

Indicators of cardiovascular risk among workers exposed to high intermittent levels of carbon disulphide

The effects of exposure to carbon disulphide have been studied mostly among workers in the viscous rayon industry, where the usual exposure profile has been relatively steady exposure over work shifts. We investigated 13 workers in a small chemical company who were exposed to low levels, peaking intermittently to relatively high levels in the range of 100-200 ppm at the end of the work shift, a pattern that may change the risk profile. Our investigation was part of a compliance order that was fought by the company and our access and follow-up was limited. Two workers had burns on their bodies associated with exposure to caustic. Four had elevations in total serum cholesterol, one had elevated serum triglycerides and three had elevations in fasting blood glucose--two of them were known to be diabetics before employment and one had a history of unexplained peripheral neuropathy. No consistent pattern suggestive of a defined lipoprotein abnormality was obvious but several atherogenic profiles were observed. Five had abnormalities on electrocardiogram, four of whom appeared to be among the most heavily exposed. The presence of these changes taken together in this context may suggest accelerated atherosclerotic changes. Tests of liver and kidney function were within the normal range for all workers, as was a complete blood count. Four of the workers had evidence of a bilateral reduction in hearing threshold at 4,000 Hz. A complete set of recommendations was forwarded to the employer, emphasizing further control of exposure to carbon disulphide, personal protection requirements and a cardiovascular risk reduction programme. Conditions improved in the plant following modifications introduced in response to a stop work order from the provincial government's occupational health and safety agency. However, a fire in 1998 put the company out of business and ended further follow-up or interventions. We conclude that these findings, while difficult to interpret because of the circumstances of the investigation, are compatible with an atherogenic effect of exposure to peaking levels of carbon disulphide. The observation should be tested in a larger population with fewer confounding factors and greater control over the investigation.

[Effects of long-term exposure to lower concentration of carbon disulfide on cardiovascular system of workers in a viscose rayon factory]

An epidemiological cross-sectional study was conducted on 99 workers exposed to lower concentration of carbon disulfide in a viscose rayon factory for a long time and 28 non-exposed ones in the same factory. Blood pressure, serum lipoproteins and electrocardiograph were detected. The results showed that neither diastolic blood pressure nor systolic one between exposed group and control group was obviously different All indicators of serum lipids and lipoproteins were not significantly different except the lipoprotein(a) of exposed group was significantly higher than that of control group, and the risk of abnormal electrocardiogram in the workers exposed to carbon disulfide was 1.1 times of those non-exposed ones but with no statistical significance. The results suggest that lipoprotein(a) can be used as a sensitive indicator for the cardiotoxic effects of carbon disulfide.

[Serum sex hormone and urinary metabolites of male workers exposed to carbon disulfide]

Serum luteotropic hormone(LH), follicle-stimulating hormone (FSH), prolectin(PRL) and testosterone (T) were determined by radioimmunoassay methods in 50 workers exposed to carbon disulfide(CS2) in a viscose rayon factory. Urinary excretion of 2-thio-thiazolidine-4-carboxilic acid (TTCA) in workers by the end of work shift was analyzed with modified high-performance liquid chromatography. The working conditions of the factory had not been changed since 1950s. The concentration of CS2, determined by Multigas Monitor (type 1320) in workplace, was (14.4 +/- 4.62) mg/m3. The results showed that: (1) serum FSH of CS2 group (10.04 +/- 7.35)IU/L was significantly higher than that of control group (7.50 +/- 7.07 IU/L), PRL of CS2 group (5.72 +/- 4.18) ng/L was significantly lower than that of control group (6.89 +/- 4.64 ng/L). Serum LH was declined with the increase of time exposed to CS2, (2) urinary TTCA in CS2 group was 1.072 +/- 1.013 mg/g Cr. Serum FSH was declined with the increase of TTCA excretion. The results suggested that the function of endocrine system was disturbed in workers exposed to CS2.

Updating of hygiene standards for carbon disulfide based on health risk assessment

In 1995 the hygiene occupational standard values of carbon disulfide (CS2) were established in Poland: the maximum allowable concentration, eight-hour time weighted average (MAC-TWA)--18 mg/m3, and the short time exposure level (STEL)--30 mg/m3. For lack of reliable retrospective data on the CS2 exposure levels in the work environment and the dose-response relationship, the following have been taken into account in establishing these values: the nervous and vascular systems are recognized as the main CS2 exposure targets; long-term exposure to CS2 in the work environment, exceeding 30 mg/m3, induces the toxic effect in the nervous and cardiovascular systems; chronic exposure to CS2 at concentration below 20 mg/m3 does not produce adverse effects in the peripheral nervous and vascular systems; coronary heart disease does not occur more frequently in workers exposed to CS2. Aiming at updating the 1995 MAC value for CS2 the authors carried out an analysis of the recent literature data on the relation between exposure levels and health risk. The results of clinical and epidemiological studies published in 1995-1997 did not provide evidence that adverse health effects in the cardiovascular and neurological systems in persons occupationally exposed to CS2 at concentration below 48 mg/m3 is likely to occur. The studies of the harmful effects of low CS2 concentration on the reproductive system have not proved that CS2 affects the embryo and fetus. Moreover, in Poland the employment of women under conditions of CS2 exposure (regardless of concentrations) during pregnancy and breast feeding is banned. Because the latest reliable studies have not indicated that chronic CS2 exposure at the level of 20-48 mg/m3 exerts toxic effect on humans, CS2 concentration of 18 mg/m3 as MAC-TWA and 30 mg/m3 as STEL, adopted in 1995, need not to be updated.

Multiple system atrophy following chronic carbon disulfide exposure

Carbon disulfide toxicity is well characterized. The principal target organ is the nervous system, although cardiovascular, reproductive, ophthalmologic, and other effects are also recognized. The neurotoxicity manifests in three ways: encephalopathy, peripheral and cranial nerve dysfunction, and movement abnormalities. This report describes a case of olivopontocerebellar atrophy, a form of multiple system atrophy, developing in an adult after over 30 years of occupational exposure to carbon disulfide. The patient presented with the insidious onset of balance problems, impotence, and irritability, without tremor, cogwheel rigidity, bradykinesia, or changes in facial expression. Over the next few years severe ataxia developed, and the clinical diagnosis was confirmed with computed tomography and magnetic resonance imaging scans. The patient experienced multiple medical complications and died approximately 9 years after diagnosis. This case is consistent with a large body of clinical and experimental literature, much of it 50 years old, showing that carbon disulfide can cause movement disorders. It also serves as a reminder that movement disorders, ranging from parkinsonism to dystonia, are associated with a variety of toxic exposures such as manganese, carbon monoxide, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and medications.

Atherosclerotic risks from chemicals: part II. A RASH analysis of in vitro and in vivo bioassay data to evaluate 45 potentially hazardous compounds

As reviewed in the Part I companion manuscript by Basavaraju and Jones (Arch Environ Contam Toxicol), atherosclerosis and carcinogenesis may share some common mechanisms of toxicological action. On that hypothesis, standardized test data taken from the Registry of Toxic Effects of Chemical Substances (RTECS) were used to compute relative potency factors for chemical compounds associated with increased risk of atherosclerosis to humans. Potencies of the different compounds were computed relative to each of six reference compounds comprised of benzo(a)pyrene, nicotine, cisplatin, adriamycin, estrogen, and 2,3,7,8-tetrachlorodibenzo-p-dioxin. Reference-specific potencies were all converted to a common numerical scale adjusted to unit potency for B(a)P. Because the list of compounds contained several antibiotics, amino acids, hormones, chemotherapeutic agents, polynuclear aromatics, alkaloids, metals, and vitamins, the standardized estimates of potency varied significantly depending on which of the six reference compounds are considered as standards of comparison. For the n - 1 other substances. Estimates of relative potency, risk coefficients, and generalized risk equations are estimated for cigarette smoke condensate, dietary cholesterol, ethanol, and carbon disulfide. From data on atherosclerosis as a result of cigarette smoking, a tentative risk was estimated as Increased Relative Risk = S (mg/kg-day)-1 x dose (mg/kg-day) x RP, where the dose is chronic intake per kilogram of body weight per day, RP is the potency of the compound of interest relative to that of benzo(a)pyrene, and S is 0.83, 0.25, 0.20, or 13 depending on whether cigarette smoke, cholesterol, ethanol, or carbon disulfide epidemiological data were used as a standard of comparison.

Neuropsychological effects of occupational exposures to carbon disulfide and hydrogen sulfide

In the framework of an extensive health survey of viscose rayon workers in Belgium, 187 workers underwent a neuropsychological examination. Of these, 120 had been exposed for at least a year to carbon disulfide (CS&inf2;) and hydrogen sulfide (H2S), and 67 served as a non-exposed control group. Measurements showed that many of the 17 jobs in the factory involved exposures to CS&inf2; ranging from 3 mg/m(3) (centrifuge operator) to 147 mg/m(3) (spinning cake regulator), far in excess of the threshold limit value (TLV) of 31 mg/m(3); H2S exposures remained below the recommended TLV of 14 mg/m(3). The neuropsychological investigation included subtests of the Wechsler Adult Intelligence Scale, the entire Wechsler Memory Scale, the Bourdon-Wiersma Test, the Santa Ana Dexterity Test, the Gibson Spiral Maze, and the Bimanual Sinusoidal Movement Test. Specific questions were included to account for the effects of age, educational level, eye complaints, alcohol consumption, medication intake, and test motivation. Only the group exposed to values exceeding three times the recommended TLV for CS2; had significant impairments in both the speed and the quality of psychomotor performance. Exposure to CS2; and H2S had no significant effect on memory and attention. Covariance analysis revealed the confounding influences of educational level and eye complaints for explaining observed "differences" in memory and attention tasks found by univariate analysis.

Cross sectional observation of the effects of carbon disulphide on arteriosclerosis in rayon manufacturing workers

OBJECTIVE

A prospective cohort study was designed to clarify the relations between occupational exposure to carbon disulphide (CS2) and its effects on arteriosclerosis in workers in 11 Japanese rayon manufacturing factories. This report is a cross sectional baseline observation in the first study year.

METHODS

Study subjects were 432 male rayon workers (mean (range) age 35.5 (19.1-47.8); duration of exposure 13.4 (0.3-29.0)) and 402 male referent workers (age 35.8 (18.9-49.8)). Exposure to CS2 was assessed by determining the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. Mean (SD) TTCA was 3.42 (2.73) mg/g creatinine (Cr) (n = 422). About a quarter of the urine samples were > 5 mg/g Cr, a biological exposure index recommended by the American Conference of Governmental Industrial Hygienists. Health effects on arteriosclerosis were evaluated by measuring blood pressure, serum lipids, pulse wave velocity of the aorta, stiffness and blood flow of the carotid artery, and blood coagulation and fibrinolysis indices, and by use of brain magnetic resonance imaging, electrocardiogram (at rest and after exercise), ophthalmograph, and Rose's questionnaire. Information on potential confounding factors was collected by self administered questionnaire.

RESULTS

Prevalence of microaneurysm of the retinal artery was significantly higher in workers exposed to CS2 (8.1%) than in referent workers (3.4%), and increased with age. Other examinations did not show any differences between the two groups even after allowance for confounding factors.

CONCLUSIONS

Significant effects of CS2 on arteriosclerosis were not found in current rayon manufacturing workers, with the exception of induction of microaneurysm of the retinal artery.