Carbon disulfide modification and impaired catabolism of low density lipoprotein

How to Differentiate General Toxicity-Related Endocrine Effects from Endocrine Disruption: Systematic Review of Carbon Disulfide Data

This review provides an overview of the assessment of the endocrine disrupting (ED) properties of carbon disulfide (CS₂), following the methodology used at the European level to identify endocrine disruptors. Relevant in vitro, in vivo studies and human data are analyzed. The assessment presented here focuses on one endocrine activity, i.e., thyroid disruption, and two main adverse effects, neurotoxicity and cardiotoxicity. The data available on the different ED or non-ED modes of action (MoA), known to trigger these adverse effects, are described and the strength of evidence of the different MoA is weighted. We conclude that the adverse effects could be due to systemic toxicity rather than endocrine-mediated toxicity. This assessment illustrates the scientific and regulatory challenges in differentiating a specific endocrine disruption from an indirect endocrine effect resulting from a non-ED mediated systemic toxicity. This issue of evaluating the ED properties of highly toxic and reactive substances has been insufficiently developed by European guidance so far and needs to be further addressed. Finally, this example also raises questions about the capacity of the technics available in toxicology to address such a complex issue with certainty.

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.

Carbon disulphide. III. Risk factors for coronary heart diseases in workers in the viscose industry

To evaluate risk factors for coronary heart disease and factors which can influence the course of acute myocardial infarction in workers exposed to CS2 we performed a cross-sectional study of 247 workers in the viscose industry. The control group of 222 men from the same plant was comparable for age, social status and physical work. The CS2 exposure determined by personal air sampling ranged from < 0.2 ppm to 65.7 ppm (median: 4.0 ppm) and the duration of exposure ranged from 4 to 220 (median: 66) months. Using a multiple linear regression model we found neither higher blood pressure at rest or after exercise, nor hyperlipoproteinaemia in a higher degree, nor lower high-density lipoprotein (HDL) or lower apolipoprotein A-I levels, nor higher blood glucose values, nor indicators of direct cardiotoxic effects or signs of disturbances in blood coagulation in the exposed group in comparison to controls. Regarding the influence of chronic exposure on the investigated parameters, we found an inverse correlation of the cumulative exposure (mean CS2 exposure in the department multiplied by the duration of work in this department) with the HDL concentration. The HDL levels correlated with the duration but not with the intensity of exposure. In the same way the apolipoprotein A-I levels showed a negative association with the duration of exposure in the exposed group as well as in the control group. The HDL concentrations showed the same trend for the controls. It therefore seems that this finding is more likely due to confounding factors than to the CS2 exposure. As all subjects (exposed and controls) have done shift work, in some cases for a long time, this kind of work could be responsible for the negative relationship between the duration of employment as a shift worker and the apolipoprotein A-I and HDL levels. At the current air-borne levels no significant differences were found between the exposed persons and the controls in the distribution frequency for blood pressure values, lipoproteins, blood glucose, blood coagulation and indicators of direct cardiotoxic effects.

Detection of carbon disulfide in breath and air: a possible new risk factor for coronary artery disease

Carbon disulfide (CS2) is toxic to the heart and arteries; chronic exposure can result in accelerated atherosclerosis and coronary artery disease in humans and animals. Exposure to CS2 was investigated in normal volunteers working in New York City, using a new and highly sensitive assay. Volatile organic compounds in breath and air were captured in adsorbent traps containing graphitized carbon and molecular sieve, then thermally desorbed, concentrated by two-stage cryofocusing, and assayed for CS2 by gas chromatography/mass spectroscopy. Breath CS2 assays were performed in 42 normal volunteers, as well as in room air and in outdoor air collected at sites in and around New York City. The assay was linear, reproducible, and sensitive to picomolar (10(-12) mol/l) quantities. CS2 was detected in all samples of breath and indoor and outdoor air (mean concentrations were 5.25 pmol/l, SD = 3.89 in breath, 8.26 pmol/l in indoor air, and 3.92 pmol/l in outdoor air) (NS). The alveolar CS2 gradient (alveolar-inspired CS2) ranged from -20.0 to 8.0 nmol/l, separating subjects into either "excreters" or "retainers" of CS2. In view of the known toxicity of CS2, atmospheric pollution with CS2 merits attention as a possible new risk factor for the development of accelerated atherosclerosis and coronary artery disease.

Calcium antagonists prevent monocyte and endothelial cell-induced modification of low density lipoproteins

Low density lipoprotein (LDL) incubated in the presence of the calcium antagonists verapamil, nifedipine and flunarizine were more resistant than control LDL to human monocyte- or endothelial cell-induced modification, as assessed by electrophoretic mobility in agarose gel, thiobarbituric acid reactive substance content, and degradation by J774 macrophages. The efficiency of the drugs was: flunarizine greater than nifedipine greater than verapamil. Moreover, a 24 h preculture with calcium antagonists significantly impaired the ability of cells to modify LDL in the absence of the drugs. All the studied drugs also inhibited copper-induced autooxidation of LDL. None of the studied calcium antagonists, at concentrations up to 10(-4) M, significantly reacted with free radicals as assessed by the 1,1-diphenyl-2-picrylhydrazyl test. It is suggested that such a protective effect of calcium antagonists against LDL peroxidation could play a role in the previously reported antiatherogenic effect of these drugs.