A critical review of the literature on carbon disulfide toxicity

Bioorthogonal Delivery of Carbon Disulfide in Living Cells

Carbon disulfide (CS2) is an environmental contaminant, which is deadly hazardous to the workers under chronic or acute exposure. However, the toxicity mechanisms of CS2 are still unclear due to the scarcity of biocompatible donors, which can release CS2 in cells. Here we developed the first bioorthogonal CS2 delivery system based on the "click-and-release" reactions between mesoionic 1,3-thiazolium-5-thiolates (TATs) and strained cyclooctyne exo-BCN-OH. We successfully realized intracellular CS2 release and investigated the causes of CS2-induced hepatotoxicity, including oxidative stress, proteotoxic stress and copper-dependent cell death. It is found that CS2 can be copper vehicles bypassing copper transporters after reacting with nucleophiles in cytoplasm, and extra copper supplementation will exacerbate the loss of homeostasis of cells and ultimately cell death. These findings inspired us to explore the anticancer activity of CS2 in combination with copper by introducing a copper chelating group in our CS2 delivery system.

Maternal residential exposure to solvents from industrial sources during pregnancy and childhood cancer risk in California

BACKGROUND

Maternal solvent exposure has been suspected to increase offspring cancer risk. The study aimed to evaluate the associations between maternal residential exposure to solvents from industrial pollution during pregnancy and childhood cancer.

METHODS

The present study included 15,744 cancer cases (aged 0-19 years at diagnosis) identified from California Cancer Registry and 283,141 controls randomly selected from California Birth Registry (20:1 frequency-matched by birth year: 1998-2016). We examined industrial releases of tetrachloroethylene and 1,1,1-trichloroethane within 3 km of the birth address, while we used a 5 km buffer for carbon disulfide. We calculated the total exposure from all linked Toxic Release Inventory sites during each index pregnancy and assigned "ever/never" and "high/low exposed/unexposed" exposure, using median values. We performed quadratic decay models to estimate cancer risks associated with maternal solvent exposure in pregnancy.

RESULTS

1,1,1-Trichloroethane was associated with rhabdomyosarcoma (adjusted Odds Ratio (aOR): 1.96; 95% Confidence Interval (CI): 1.16, 3.32) in the "ever exposed" group. Ever exposure to carbon disulfide was associated with increased risks of medulloblastoma (OR = 1.85, 95% CI 1.01, 3.40) and ependymoma (OR = 1.63, 95% CI 0.97, 2.74).

CONCLUSIONS

Overall, our findings suggested maternal residential exposure to solvents from industrial sources might be associated with elevated childhood cancer risks.

Chronic carbon disulfide exposure induces parkinsonian pathology via α-synuclein aggregation and necrosome complex interaction

Exposure to carbon disulfide (CS2) has been associated with an increased incidence of parkinsonism in workers, but the mechanism underlying this association remains unclear. Using a rat model, we investigated the effects of chronic CS2 exposure on parkinsonian pathology. Our results showed that CS2 exposure leads to significant motor impairment and neuronal damage, including loss of dopaminergic neurons and degeneration of the substantia nigra pars compacta (SNpc). The immunoassays revealed that exposure to CS2 induces aggregation of α-synuclein and phosphorylated α-synuclein, as well as activation of necroptosis in the SNpc. Furthermore, in vitro and in vivo experiments demonstrated that the interaction between α-synuclein and the necrosome complex (RIP1, RIP3, and MLKL) is responsible for the loss of neuronal cells after CS2 exposure. Taken together, our results demonstrate that CS2-mediated α-synuclein aggregation can induce dopaminergic neuron damage and parkinsonian behavior through interaction with the necrosome complex.

Hysteresis of heavy metals uptake induced in Taraxacum officinale by thiuram

Dandelion (Taraxacum officinale) yields active substances frequently used in herbal medicinal preparations. Its plantations are exposed to fungal plagues which pose a threat to herbal crops. The aim of this study was to evaluate the long time effects of a fungicide thiuram on dandelion growth and photosynthesis. Additionally, the manganese, iron, copper, zinc, cadmium, and lead uptake and transport were also investigated. Plants were cultivated under greenhouse conditions by the pot method in a universal flowering soil. The elements content in soil and plants were determined by the HR-CS FAAS spectrometer. Thiuram concentrations were established by the HPLC. Those analyses showed that almost 80% of thiuram decomposed within two weeks of its application. The photosynthesis indicators suggested, that plants were in good conditions and the fungicide supplementation facilitated plant growth. The latter could be prompted by thiuram acting as a sulfur rich chemical micro fertilizer. The hypothesis, that thiuram significantly affects heavy metals interactions in dandelion was proved by the one-way analysis of variance. Notable, metals uptake did not completely recover after fungicide decomposition for all investigated elements except iron We suggest to define this chemically induced, time-dependent heavy metals migrations in the soil-plant system as hysteresis of heavy metals uptake.

Service Innovation in Human Resource Management During COVID-19: A Study to Enhance Employee Loyalty Using Intrinsic Rewards

This research focuses on the employee loyalty aspect of private hospitals in Pakistan during the COVID-19 pandemic, seriously impacted by strict work demand and work-family conflict. To manage this issue, social rewards and psychological rewards played a role as a mediator. The study uses a causal research design with a correlational study design in a non-contrived environment. Minimal researcher interference has been assured. AMOS 24 has been used to deal with the mediation in study design with bootstrap methodology. The study was conducted on 250 nurses of different private hospitals across Punjab province using a proportionate stratified sampling technique. A finding of this study suggests that nurses remain loyal to their organizations despite having uncompromising work demands and facing work-family conflict when they are provided with social and psychological rewards on their job by their organizations.

Factors Affecting the Nonsolvent-Induced Phase Separation of Cellulose from Ionic Liquid-Based Solutions

In the present work, we report for the first time an in-depth study of the factors influencing porous cellulose film structure formation during the nonsolvent-induced phase separation (NIPS) process from biopolymer solutions in ionic liquid-based solvents. The length of the alkyl chain of the ionic liquid's cation, the solvent/co-solvent ratio, and the type of the cellulose precursor used were found to have great influence both on cellulose solution formation and properties and to the NIPS process with water acting as nonsolvent. In the undiluted form, both studied ionic liquids proved to dissolve almost equally well the cellulose; however, due to differences in viscosities of the formed biopolymer solutions and due to differences in miscibility with water of the two ionic liquids, the used ionic liquid had a strong influence on the film's porous structure formation. The use of increasing amounts of an aprotic co-solvent, here dimethylsulfoxide, improved biopolymer solubilization and also led to the formation of a more pronounced macroporous structure during the NIPS process. The cellulose type also affected the porous structure generation during the NIPS process: with the increase of the molecular weight of the precursor, the viscosity of the formed biopolymer solution increased and the tendency to generate macroporous structures decreased.

Sensory neurons expressing the atypical olfactory receptor guanylyl cyclase D are required for the acquisition of odor preferences by mice in diverse social contexts

Animals use social communication to learn important information from conspecifics that can guide appropriate behavioral choices. For example, during the social transmission of food preference (STFP), conspecific semiochemicals detected by mouse olfactory sensory neurons (OSNs) expressing the atypical olfactory receptor guanylyl cyclase D (GC-D+ OSNs) promote the acquisition of food preferences in the recipient animal, mitigating the risk of ingesting food contaminated with toxins or pathogens. However, it is unclear if GC-D+ OSNs mediate preference learning outside this specific context. Here, we report that GC-D+ OSNs are required for the acquisition of odor preferences by both adult and juvenile mice, and that GC-DD-dependent preference could be formed for conditionally aversive odors. We used a two-choice olfactory behavioral test to assess odor preferences in adult Gucy2d +/+, +/- and -/- mice that encountered novel odors together with GC-D+ OSN stimuli (guanylin family peptides), during social investigation of a live conspecific, or during suckling as pups. Gucy2d +/+ and +/- mice (which express functional GC-D), but not Gucy2d -/- littermates, successfully acquire a preference for the demonstrated odor in any of these behavioral paradigms. Mice could even acquire a GC-D-dependent preference for odors to which they had recently formed a conditioned aversion. Together, these results demonstrate that GC-D+ OSNs mediate the acquisition of socially-transmitted odor preferences in different social and experiential contexts and at different life stages.

Effects of co-exposure to CS2 and noise on hearing and balance in rats: continuous versus intermittent CS2 exposures

Background

Carbon disulfide (CS₂) exacerbates the effect of noise on hearing, and disrupts the vestibular system. The goal of this study was to determine whether these effects are also observed with intermittent CS₂ exposure.

Methods

Rats were exposed for 4 weeks (5 days/week, 6 h/day) to a band noise at 106 dB SPL either alone or combined with continuous (63 ppm or 250 ppm) or intermittent (15 min/h or 2 × 15 min/h at 250 ppm) CS₂. Hearing function was assessed by measuring distortion product otoacoustic emissions (DPOAEs); balance was monitored based on the vestibulo-ocular reflex (VOR). Functional measurements were performed before, at the end of exposure and 4 weeks later. Histological analyses of the inner ear were also performed following exposure and after the 4-week recovery period.

Results

The results obtained here confirmed that CS₂ exposure exerts two differential temporary effects on hearing: (1) it attenuates the noise-induced DPOAE decrease below 6 kHz probably through action on the middle ear reflex when exposure lasts 15 min per hour, and (2) continuous exposure to 250 ppm for 6 h extends the frequency range affected by noise up to 9.6 kHz (instead of 6 kHz with noise alone). With regard to balance, the VOR was reversibly disrupted at the two highest doses of CS₂ (2 × 15 min/h and continuous 250 ppm). No morphological alterations to the inner ear were observed.

Conclusion

These results reveal that short periods of CS₂ exposure can alter the sensitivity of the cochlea to noise at a dose equivalent to only 10 times the short-term occupational limit value, and intermittent exposure to CS₂ (2 × 15 min/h) can alter the function of the vestibular system.

Toxic Peripheral Neuropathies: Agents and Mechanisms

Toxic peripheral neuropathies are an important form of acquired polyneuropathy produced by a variety of xenobiotics and different exposure scenarios. Delineating the mechanisms of neurotoxicants and determining the degenerative biological pathways triggered by peripheral neurotoxicants will facilitate the development of sensitive and specific biochemical-based methods for identifying neurotoxicants, designing therapeutic interventions, and developing structure-activity relationships for predicting potential neurotoxicants. This review presents an overview of the general concepts of toxic peripheral neuropathies with the goal of providing insight into why certain agents target the peripheral nervous system and produce their associated lesions. Experimental data and the main hypotheses for the mechanisms of selected agents that produce neuronopathies, axonopathies, or myelinopathies including covalent or noncovalent modifications, compromised energy or protein biosynthesis, and oxidative injury and disruption of ionic gradients across membranes are presented. The relevance of signaling between the main components of peripheral nerve, that is, glia, neuronal perikaryon, and axon, as a target for neurotoxicants and the contribution of active programmed degenerative pathways to the lesions observed in toxic peripheral neuropathies is also discussed.

Evaluation Selenocysteine Protective Effect in Carbon Disulfide Induced Hepatitis with a Mitochondrial Targeting Ratiometric Near-Infrared Fluorescent Probe

As important active sites of oxidoreductase in mitochondria, selenocysteine (Sec) takes the responsibility for cytoprotective effect and intracellular redox homeostasis. Carbon disulfide (CS₂) is a common solvent in industry, which can inhibit the activities of oxidoreductase and induce oxidative stress. It is necessary to investigate the cytoprotective effect of Sec against CS₂ exposure. After integrated, the response moiety 2,4-dinitrobenzenesulfonamide and mitochondrial targeting moiety into the near-infrared heptamethine cyanine fluorophore, we develop a mitochondrial targeting near-infrared ratiometric fluorescent probe Mito- diNO₂ for the selective and sensitive analysis of Sec concentration fluctuations in living cells and in mice models under the stimulation of CS₂. The probe can effectively accumulate in mitochondria and selectively detect the endogenous Sec concentrations in BRL 3A, RH-35, HL-7702, HepG2, and SMMC-7721 cell lines. The results indicate that CS₂ exposure can lead to a decrease of Sec level and result in mitochondrial related acute inflammation. The exogenous supplement of Sec can protect cells from oxidative damage and reduce the symptoms of inflammation. We also establish CS₂ induced acute and chronic hepatitis mice models to examine the tissue toxicity of CS₂ and cytoprotection of Sec in liver. The organism can increase the concentration of Sec to deal with the damage caused by CS₂ in acute hepatitis mice model. Also the exogenous supplement of Sec for the two mice models can effectively defend the CS₂ induced liver damage. The real-time imaging of Sec concentrations in liver can be used to assess the degrees of liver injury during CS₂ poisoning. The above applications make our probe a potential candidate for the clinical accurate diagnosis and treatment of CS₂ poisoning.

Continuous exposure to low-frequency noise and carbon disulfide: Combined effects on hearing

Carbon disulfide (CS₂) is used in industry; it has been shown to have neurotoxic effects, causing central and distal axonopathies.However, it is not considered cochleotoxic as it does not affect hair cells in the organ of Corti, and the only auditory effects reported in the literature were confined to the low-frequency region. No reports on the effects of combined exposure to low-frequency noise and CS₂ have been published to date. This article focuses on the effects on rat hearing of combined exposure to noise with increasing concentrations of CS₂ (0, 63,250, and 500ppm, 6h per day, 5 days per week, for 4 weeks). The noise used was a low-frequency noise ranging from 0.5 to 2kHz at an intensity of 106dB SPL. Auditory function was tested using distortion product oto-acoustic emissions, which mainly reflects the cochlear performances. Exposure to noise alone caused an auditory deficit in a frequency area ranging from 3.6 to 6 kHz. The damaged area was approximately one octave (6kHz) above the highest frequency of the exposure noise (2.8kHz); it was a little wider than expected based on the noise spectrum.Consequently, since maximum hearing sensitivity is located around 8kHz in rats, low-frequency noise exposure can affect the cochlear regions detecting mid-range frequencies. Co-exposure to CS₂ (250-ppm and over) and noise increased the extent of the damaged frequency window since a significant auditory deficit was measured at 9.6kHz in these conditions.Moreover, the significance at 9.6kHz increased with the solvent concentrations. Histological data showed that neither hair cells nor ganglion cells were damaged by CS₂. This discrepancy between functional and histological data is discussed. Like most aromatic solvents, carbon disulfide should be considered as a key parameter in hearing conservation régulations.

Carbon disulfide. Just toxic or also bioregulatory and/or therapeutic?

The overview presented here has the goal of examining whether carbon disulfide (CS₂) may play a role as an endogenously generated bioregulator and/or has therapeutic value.

Oxidative Stress Mediated Hippocampal Neuron Apoptosis Participated in Carbon Disulfide-Induced Rats Cognitive Dysfunction

Occupational exposure to carbon disulfide (CS₂) exhibits central nervous systems toxicity. But the mechanism is unclear. The present study was designed to investigate the relationship between the CNS damage and cognitive dysfunction caused by CS₂, and eventually reveal the possible oxidative-related mechanism of hippocampus pathological changes in CS₂ exposed rats. Male Wistar rats were administrated with CS₂ at dosage of 200, 400 and 600 mg/kg for consecutive 20 days, respectively. Cognitive performances were evaluated by Morris water maze tests. Thionin and immunohistochemical analysis were used to investigate the hippocampal neuron damage, and the expression of apoptosis related proteins (cleaved-caspase 3, Bax and Bcl-2) were detected to explore the possible mechanisms of neuronal loss. Oxidative stress parameters were checked by commercial assay kits. Rats exposed to CS₂ displayed cognitive dysfunction manifested as decreased spatial learning ability and memory lesion. Pathological changes and significant neuron loss were observed in hippocampus, especially in CA1 and CA3 sub-regions. Mitochondria-dependent apoptosis pathway was implicated in the CS₂-induced neuronal loss which was demonstrated by the up-regulation of cleaved-caspase 3 and Bax accompanied with down-regulation of Bcl-2. Furthermore, extensive oxidative stress induced by CS₂ was also revealed by the measurement of ROS, RNS, MDA, GSH&GSSG and antioxidant enzymes (CAT, T-SOD, and GSH-Px). Our study suggested that oxidative stress mediated hippocampal neuron apoptosis might play an important role in CS₂ induced CNS damage and cognitive dysfunction.

Renal pathology in patients with occupational exposure to carbon disulphide: A case series

AIM

Carbon disulphide (CS₂ ) is widely used as an organic solvent. However, there is little information available regarding the clinical manifestations and the pathological features of kidney injury caused by CS₂ . The current study aimed to describe the renal manifestations of a group of patients with long-term occupational exposure to CS₂ .

METHODS

Ten patients with long-term exposure to CS₂ and visiting a single centre were enrolled, with their clinical features recorded. Renal biopsies were taken from all patients, and their pathological findings were documented.

RESULTS

All patients came from the same chemical fibre factory. Their mean age at enrollment was 36.9 ± 2.4 years, and each patient had a CS₂ exposure duration exceeding 10 years. Eight patients (80%) presented with proteinuria and none had hematuria. Two patients (20%) had underlying hypertension and five (50%) had increased serum creatinine levels. Light microscopic examination of their renal biopsy specimens revealed diffuse mesangial cell proliferation and mesangial hyperplasia in all patients. Moreover, three patients (30%) had nodular hyperplasia, resembling the lesions of diabetic nephropathy. Variable degrees of tubular atrophy and interstitial infiltrations of lymphocytes and monocytes were observed in all patients. Similarly, lectron microscopic examination showed glomerular mesangial cell proliferation and mesangial hyperplasia. Immunopathological staining for IgA and IgG, complements or hepatitis B markers (hepatitis B surface antigen and e antigen-antibody) are negative in all patients.

CONCLUSION

Long-term occupational exposure to CS₂ may be associated with renal injury, although the renal pathological features are often non-specific.

Epidemic Parenteral Exposure to Volatile Sulfur-Containing Compounds at a Hemodialysis Center

Objective:

To determine the cause of acute illness on August 30, 2000, among patients at an outpatient dialysis center (center A).

Design:

We performed a cohort study of all patients receiving dialysis on August 30, 2000; reviewed dialysis procedures; and analyzed dialysis water samples using microbiologic and chemical assays.

Setting:

Dialysis center (center A).

Patients:

A case-patient was defined as a patient who developed chills within 5 hours after starting hemodialysis at center A on August 30, 2000.

Results:

Sixteen (36%) of 44 patients at center A met the case definition. All case-patients were hospitalized; 2 died. Besides chills, 15 (94%) of the case-patients experienced nausea; 12 (75%), vomiting; and 4 (25%), fever. Illness was more frequent on the second than the first dialysis shift (16 of 20 vs 0 of 24, P < .001); no other risk factors were identified. The center's water treatment system had received inadequate maintenance and disinfection and a sulfurous odor was noted during sampling of the water from the reverse osmosis (RO) unit. The water had elevated bacterial counts. Volatile sulfur-containing compounds (ie, methanethiol, carbon disulfide, dimethyldisulfide, and sulfur dioxide) were detected by gas chromatography and mass spectrometry in 8 of 12 water samples from the RO unit and in 0 of 28 samples from other areas (P < .001). Results of tests for heavy metals and chloramines were within normal limits.

Conclusions:

Parenteral exposure to volatile sulfur-containing compounds, produced under anaerobic conditions in the RO unit, could have caused the outbreak. This investigation demonstrates the importance of appropriate disinfection and maintenance of water treatment systems in hemodialysis centers.

Investigation of adsorption properties of CS2 on interior and exterior surfaces of single-walled silicon-carbide nanotubes and effect of applied electric field: electronic structure, charge density and NMR studies

The adsorption behavior of CS₂ on silicon-carbide nanotube has been investigated using B3LYP/6-31G*. 3D NBO contour plots illustrating the interaction between lone pair orbitals of S atom of CS₂ with σ*Si12–C13 of the nanotube in configuration 2.

Activation of lysosomal degradative pathway in spinal cord tissues of carbon disulfide-treated rats

Chronic exposure to carbon disulfide (CS₂) can induce polyneuropathy in occupational worker and experimental animals, but underlying mechanism for CS₂ neuropathy is currently unknown. In the present study, male Wistar rats were randomly divided into three experimental groups and one control group. The rats in experimental groups were treated with CS₂ by gavage at dosages of 200, 400 and 600 mg/kg/day respectively, six times per week for 6 weeks. The formation of autophagosomes and lysosomes in motor neurons of rat spinal cord was observed by transmission electron microscopy, the level of autophagy-related proteins, lysosome-associated membrane protein 1 (LAMP-1), and cathepsin B in spinal cord tissues was determined by Western blot analysis, and the activity of cathepsin B was measured by fluorescence assay. The results demonstrated that the number of lysosomes in motor neurons was markedly increased in CS₂-treated rats. In the meantime, the administration of CS₂ significantly increased the level of microtubule-associated protein light chain 3-II (LC3-II), Atg1, UVRAG and LAMP-1 in rat spinal cord. Furthermore, the content and activity of cathepsin B in rat spinal cord also showed a significant elevation. Taken together, this study suggested that CS₂ intoxication was associated with the activation of lysosomal degradative machinery, which might play a protective role against CS₂-induced neuronal damage.

The emerging role of outdoor and indoor air pollution in cardiovascular disease

Outdoor and indoor air pollution poses a significant cardiovascular risk, and has been associated with atherosclerosis, the main underlying pathology in many cardiovascular diseases. Although, it is well known that exposure to air pollution causes pulmonary disease, recent studies have shown that cardiovascular health consequences of air pollution generally equal or exceed those due to pulmonary diseases. The objective of this article is to evaluate the current evidence on the emerging role of environmental air pollutions in cardiovascular disease, with specific focus on the types of air pollutants and mechanisms of air pollution-induced cardiotoxicity. Published literature on pollution was systematically reviewed and cited in this article. It is hoped that this review will provide a better understanding of the harmful cardiovascular effects induced by air pollution exposure. This will help to bring a better understanding on the possible preventive health measures and will also serve regulatory agencies and researchers. In addition, elucidating the biological mechanisms underlying the link between air pollution and cardiovascular disease is an essential target in developing novel pharmacological strategies aimed at decreasing adverse effects of air pollution on cardiovascular system.

An olfactory subsystem that detects carbon disulfide and mediates food-related social learning

Olfactory signals influence social interactions in a variety of species. In mammals, pheromones and other social cues can promote mating or aggression behaviors; can communicate information about social hierarchies, genetic identity and health status; and can contribute to associative learning. However, the molecular, cellular, and neural mechanisms underlying many olfactory-mediated social interactions remain poorly understood. Here, we report that a specialized olfactory subsystem that includes olfactory sensory neurons (OSNs) expressing the receptor guanylyl cyclase GC-D, the cyclic nucleotide-gated channel subunit CNGA3, and the carbonic anhydrase isoform CAII (GC-D(+) OSNs) is required for the acquisition of socially transmitted food preferences (STFPs) in mice. Using electrophysiological recordings from gene-targeted mice, we show that GC-D(+) OSNs are highly sensitive to the volatile semiochemical carbon disulfide (CS(2)), a component of rodent breath and a known social signal mediating the acquisition of STFPs. Olfactory responses to CS(2) are drastically reduced in mice lacking GC-D, CNGA3, or CAII. Disruption of this sensory transduction cascade also results in a failure to acquire STFPs from either live or surrogate demonstrator mice or to exhibit hippocampal correlates of STFP retrieval. Our findings indicate that GC-D(+) OSNs detect chemosignals that facilitate food-related social interactions.

The effects of carbon disulfide on male sexual function and semen quality

A cross-sectional study was initiated to clarify whether the current level of exposure to carbon disulphide (CS(2)) is low enough to prevent occurrence of subclinical health impairments. This paper describes the effects of exposure to CS(2) on male sexual function and semen quality in a baseline observation. The effects of CS(2) on male sexual function were evaluated, including number of sexual encounters and length of sexual encounters related to solvents in 80 male workers exposed to CS(2) and 49 reference workers from the filature and cotton pulp departments of a fabric factory in China. And the semen samples were obtained from 43 of the exposed and 35 of the control. Adjustment was made for potential confounding factors such as age or alcohol drinking. Exposure to CS(2) was dichotomized by job type. The rate of sexual dysfunction was higher, number of sexual encounters was lower, and length of sexual encounters was shorter compared with the control (p < 0.001). It was indicated that exposed workers had fewer semen quantity, longer liquefaction time, lower acrosomal membrane integrity rate, vitality and density, and more deformity of semen than the control (p < 0.01). The age and type of work played the most important roles in sexual dysfunction by the multinomial logistic regression analysis (p < 0.01).The duration of exposure had the effect on sexual function and semen quality but no statistical significance (p > 0.05). Clinical effects on the male sexual function and semen quality were found in the workers exposed to CS(2).

Isolation of a carbon disulfide utilizing Thiomonas sp. and its application in a biotrickling filter

The carbon disulfide (CS2)-oxidizing bacterium Thiomonas sp. WZW was enriched and isolated using activated sewage sludge as inoculum. Growth of Thiomonas sp. WZW was observed on CS2, thiosulfate, dimethylsulfide (DMS), dimethyldisulfide (DMDS), and H2S. No growth occurred on dimethylsulfoxide, methanol, acetate, and on complex media with glucose, yeast extract, or tryptone. DMDS-grown cells respired CS2, DMS, and DMDS, while thiosulfate-grown cells did not respire CS2. Chemostat cultures growing on thiosulfate could be rapidly adapted to growth on CS2. Growth was observed between pH 6 and 8. The Ks values for CS2, thiosulfate, and sulfide of CS2-grown cells were between 5 and 10 microM. CS2 was inhibitory above 0.3 mM. A lab-scale biotrickling filter with lava stone as carrier material for treatment of CS2-polluted air was inoculated with Thiomonas sp. WZW. A rapid start up (95% removal in 1 week) was obtained at an inlet CS2 concentration of 2 cmol l(-1) and an initial space velocity (SV) of 54 h(-1). Subsequent thiosulfate addition for a week during start up increased the removal to 99%. The step-wise increase of SV to 130 h(-1) and a CS2 concentration to 3 micromol l(-1) resulted in a stable performance with a removal efficiency of 95%. Feeding mixtures of volatile sulfur compounds showed simultaneous conversion of H2S, CS2, dimethyldisulfide (DMDS), and DMS, with a preference in this order.

Carbon Disulfide-Induced Alterations of Neurofilaments and Calpains Content in Rat Spinal Cord

To investigate the mechanism of carbon disulfide-induced neuropathy, male Wistar rats were randomly divided into two experimental groups and one control group. The rats in two experimental groups were treated with carbon disulfide by gavage at dosages of 300 and 500 mg/kg/day, respectively, five times per week for 12 weeks. Spinal cords of carbon disulfide-intoxicated rats and their age-matched controls were Triton-extracted and ultracentrifuged to yield a pellet fraction of neurofilament (NF) polymer and a corresponding supernatant fraction. Then, the contents of NF triplet proteins (NF-H, NF-M, NF-L) and two calpain isoforms (m-calpain and mu-calpain) in both fractions were determined by immunoblotting. In the meantime, the mRNA levels of NF-H, NF-M, and NF-L in spinal cords were quantified using reverse transcriptase-polymerase chain reaction. Results showed that in the pellet fraction, the contents of three NF subunits in both treated groups decreased significantly except NF-L in low dose group. In the supernatant fraction, the pattern of NFs alteration varied according to dose-levels. Compared to controls, three neurofilmant subunits in the high dose group displayed significant reduction consistently. However, in the low dose group, they remained unaffected. As for calpains, the contents of mu-calpain in both fractions increased significantly regardless of carbon disulfide dose-levels. Meanwhile, m-calpain demonstrated a significant decline in the supernatant fraction, and remained unchangeable in the pellet fraction compared to the control group. Furthermore, the levels of mRNA expression of NF-H, NF-M, and NF-L genes were elevated consistently in CS(2)-treated groups. These findings suggested that carbon disulfide intoxication was associated with obvious alterations of NFs content in rat spinal cord, which might be involved in the development of carbon disulfide neurotoxicity.

Carbon Disulfide-Induced Changes in Cytoskeleton Protein Content of Rat Cerebral Cortex

To investigate the mechanism of carbon disulfide-induced neuropathy, male wistar rats were administrated by gavage at dosage of 300 or 500 mg/kg carbon disulfide, five times per week for 12 weeks. By the end of the exposure, the animals produced a slight or moderate level of neurological deficits, respectively. Cerebrums of carbon disulfide-intoxicated rats and their age-matched controls were Triton-extracted and centrifuged at a high speed (100,000 x g) to yield a pellet fraction of NF polymer and a corresponding supernatant fraction, which presumably contained mobile monomer. Then, the contents of six cytoskeletal protein (NF-L, NF-M, NF-H, alpha-tubulin, beta-tubulin, and beta-actin) in both fractions were determined by immunoblotting. Results showed that the contents of the three neurofilament subunits in the pellet and the supernatant fraction decreased significantly regardless of dose levels (P<0.01). As for microtubule proteins, in the pellet fraction of cerebrum, the levels of alpha-tubulin and beta-tubulin demonstrated some inconsistent changes. However, in the supernatant fractions, the content of alpha-tubulin and beta-tubulin increased significantly in both two dose groups (P<0.01). In comparison to neurofilament and tubulin proteins, the content of beta-actin changed less markedly, only the supernatant fraction of the high dose group displayed significant increase (P<0.01), but the others remained unaffected. These findings suggested that the changes of cytoskeleton protein contents in rat cerebrum were associated with the intoxication of carbon disulfide, which might be involved in the development of carbon disulfide neurotoxicity.

Topical exposure to carbon disulfide induces epidermal permeability alterations in physiological and pathological changes

Carbon disulfide (CS2) has been suggested its possible skin toxicity. Neither a dose-response relationship nor any mechanism of CS2-exposure regarding epidermal permeability alterations has been postulated. The objectives of this study were to evaluate the dose-dependent association and the pathological changes with CS2 topically applied to mouse epidermis. Four concentrations of CS2 (0% (controls), 10%, 15%, and 20% in ethanol) were topically applied to a 1.8 cm2 area of the lateral abdomen of female nude mice for 10 min. Time-series transepidermal water loss (TEWL) profile, morphological examinations by both light microscopy (hematoxylin/eosin stain and Nile Red stain) and electronic microscopy, and lipid analysis by high performance thin-layer chromatography (HPTLC) were used to evaluate the epidermal impairment. We found no recovery occurred within 72 h exposure to 20% CS2 in contrast to substantial recovery found in 10% and 15% CS2-exposure. Clear dose-dependent fashions were shown in TEWL elevations, recovery retardation, and lipid extraction across the ethanol (control), 10%, 15%, and 20% CS2 exposures. Two mechanistic pathways were raised to account for CS2-induced epidermal alterations: intercellular lipid depletion and keratinocyte damage. A study with different test animal species is warranted owing to the discrepancies in epidermis between nude mice and other species.

Neurotoxicity of carbonyl sulfide in F344 rats following inhalation exposure for up to 12 weeks

Carbonyl sulfide (COS), a high-priority Clean Air Act chemical, was evaluated for neurotoxicity in short-term studies. F344 rats were exposed to 75-600 ppm COS 6 h per day, 5 days per week for up to 12 weeks. In rats exposed to 500 or 600 ppm for up to 4 days, malacia and microgliosis were detected in numerous neuroanatomical regions of the brain by conventional optical microscopy and magnetic resonance microscopy (MRM). After a 2-week exposure to 400 ppm, rats were evaluated using a functional observational battery. Slight gait abnormality was detected in 50% of the rats and hypotonia was present in all rats exposed to COS. Decreases in motor activity, and forelimb and hindlimb grip strength were also detected. In rats exposed to 400 ppm for 12 weeks, predominant lesions were in the parietal cortex area 1 (necrosis) and posterior colliculus (neuronal loss, microgliosis, hemorrhage), and occasional necrosis was present in the putamen, thalamus, and anterior olivary nucleus. Carbonyl sulfide specifically targeted the auditory system including the olivary nucleus, nucleus of the lateral lemniscus, and posterior colliculus. Consistent with these findings were alterations in the amplitude of the brainstem auditory evoked responses (BAER) for peaks N3, P4, N4, and N5 that represented changes in auditory transmission between the anterior olivary nucleus to the medial geniculate nucleus in animals after exposure for 2 weeks to 400 ppm COS. A concentration-related decrease in cytochrome oxidase activity was detected in the posterior colliculus and parietal cortex of exposed rats as early as 3 weeks. Cytochrome oxidase activity was significantly decreased at COS concentrations that did not cause detectable lesions, suggesting that disruption of the mitochondrial respiratory chain may precede these brain lesions. Our studies demonstrate that this environmental air contaminant has the potential to cause a wide spectrum of brain lesions that are dependent on the degree and duration of exposure.

A six year follow up study of the subclinical effects of carbon disulphide exposure on the cardiovascular system

AIMS

A six year prospective cohort study was conducted to clarify whether the current carbon disulphide (CS2) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the effects on the cardiovascular systems.

METHODS

The study subjects were 432 male workers exposed to CS2 and 402 non-exposed workers in Japan, all of whom were examined in 1992-93. A total of 251 CS2 exposed, 140 formerly exposed, and 359 non-exposed workers participated in the follow up survey (follow up rate 89.9%) in 1998-99. Mean duration of exposure was 19.3 years at the end the study. Mean CS2 and 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations were 5.0 ppm and 1.6 mg/g creatinine. Health items examined were serum biochemical indices including lipids and coagulation-fibrinolysis factors, blood pressure, aortic stiffness, ophthalmography, and electrocardiography at rest and after Master's double 2 step test. Potential confounding factors were adjusted for.

RESULTS

Incidence of ischaemic findings, defined as Minnesota codes I, IV(1-3), V(1-3) (at rest and after the load), or receiving treatment for ischaemia, was significantly higher in the exposed workers, especially for the spinning/refining workers (adjusted OR 2.1; 95% CI 1.1 to 4.0) or the highest quartile of six year mean TTCA (adjusted OR 3.9; 95% CI 1.8 to 8.7), although the observed increase in risk was diminished when rigorous ECG criteria were applied. Incidence of retinal microaneurysm was increased with marginal significance. Among cardiovascular risk factors we examined, only blood pressure values were significantly increased in the exposed workers.

CONCLUSIONS

Increased risk of ischaemic electrocardiogram findings among Japanese viscose rayon workers was observed. Although its clinical significance is to be discussed, the current Japanese occupational exposure limit for CS2, 10 ppm, would be high to prevent subclinical cardiovascular effects in this study population.

Carbon disulfide cytotoxicity on cultured cardiac myocyte cell of rats

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

Lack of Relationship between Occupational Exposure to Carbon Disulfide and Endocrine Dysfunction: A Six‐year Cohort Study of the Japanese Rayon Workers

OBJECTIVES

A six-year prospective cohort study was conducted to clarify whether the current carbon disulfide (CS2) exposure level is low enough to prevent subclinical health impairment and/or to ameliorate health effects due to previous high exposure. This paper describes the follow-up results, exposure assessment, and effects on the endocrine system.

METHODS

The study subjects were 432 male workers exposed to CS2 at one of the 11 rayon factories in Japan and 402 referent workers from the same factories, all of whom were examined in 1992-93. 251 CS2-exposed, 140 former-exposed and 359 referent workers participated in the follow-up survey (follow-up rate 89.9%) in 1998-99. Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) at the end of a shift as internal exposure index and the time-weighted average CS2 concentration as external exposure index were measured twice a year from 1992-1993. By using various blood indices, we evaluated effects on thyroid, hypophysis, and gonad function, as well as effects on glucose metabolism. Information on potential confounding factors, such as age, smoking and alcohol drinking, were collected and adjusted for.

RESULTS

When the individual exposure level was represented by arithmetic mean for TTCA and CS2 concentration, geometric means (SD) of CS2 workers were 1.61 (1.91) mg/g.crea and 5.02 (1.84) ppm, respectively. There were no exposure-related differences in glucose metabolism or any of the endocrinological indices.

CONCLUSIONS

No biologically significant effects of CS2 were found on endocrine function in Japanese rayon manufacturing workers when the average internal and external exposure levels were maintained below the current occupational exposure limit.

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.

Biological monitoring of carbon disulphide: kinetics of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) in exposed workers

The objectives of this study was to establish the kinetics of urinary 2-thiothiazolidine-4-carboxylic acid (U-TTCA) for workers exposed to carbon disulphide (CS2) and to investigate the effects of volume and creatinine adjustment methods for urine measurement. Ten workers in the spinning department of a rayon factory were individually monitored for airborne CS2 concentrations, with consecutive urine samples collected for 24-38 hours after termination of exposure. The U-TTCA, urine volume and creatinine level were measured for each sample. First-order and biphasic kinetics were determined using the curve-fit method, for the measurement series. For the first-order kinetics linearity fit, statistically significant correlation coefficients of 0.74-0.98 and 0.86-0.99 were derived for the volume- and creatinine-adjusted methods, respectively. For the biphasic kinetics approach, the overall correlation coefficients were 0.544-0.999 and 0.171-0.999 for the first and second phases of the creatinine-adjusted method, respectively. A post-shift U-TTCA of 3.0 mg/g Cr. equivalent, 40% below the current BEI setting at nearly PEL exposed level, was found. In conclusion, first-order kinetic response was confirmed for U-ITCA. Both volume- and creatinine-based urine adjustment are satisfactory for TTCA assessment as a biomarker of individual CS2 exposure although the correlation for creatinine-based measurement was modestly superior to the volume-based analogue. Based on the results of this study,we recommend a re-evaluation of the current biological exposure index of 5 mg/g creatinine at a CS2 exposure level of 10 ppm.

Carbon disulfide cytotoxicity on cultured cardiac myocytes of rats

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

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.

Increased carbon disulfide-stimulated chemiluminescence in the pyrogallol-luminol system

We studied the effect of carbon disulphide (CS2) on the generation of superoxide anion (O2-*) and its chemiluminescence (CL) in the pyrogallol-luminol system. Testing was conducted with the pyrogallol-luminol system to observe the CL dynamic curve of CS2 and the inhibition by superoxide dismutase (SOD) on CL induced by CS2. Compared with the ethanol solvent control, CS2 enhanced the emission intensity of CL and delayed the peak time. There was a significant dose-concentration relationship between CS2 concentrations (10, 40, 80 mg/mL) and CL peak (r = 0.975 p = 0.012) and CS2 concentrations and peak time (r = 0.990, p = 0.005). The CL peak at 80 mg/mL CS2 was higher than that in a background without ethanol. The enhanced CL evoked by CS2 could be inhibited by SOD. The results suggest that CS2 can induce the pyrogallol-luminol system to generate an increased amount of O2-* and delay the CL peak time.

Influence of carbon disulphide on hydroxyl radicals in the phenanthroline chemiluminescence system

We investigated the effects of carbon disulphide (CS2) on hydroxyl radical generation using the phenanthroline chemiluminescence system. The influence of CS2 on the phenanthroline chemiluminescence system without CuSO4 and vitamin C were tested. The results showed that CS2 enhanced the emission intensity of chemiluminescence and advanced the peak time of the chemiluminescence. There was a dose-effect relationship between CS2 concentrations (0-160 mg/ml) and chemiluminescence peak intensity (r = 0.955, R2 = 0.913, p = 0.003), as well as CS2 concentrations and peak time (r = -0.927, R2 = 0.860, p = 0.008). The enhanced chemiluminescence induced by CS2 could be inhibited by thiourea, and the inhibition rate gradually deceased along with increasing CS2 concentration (r = -0.816, R2 = 0.666, p = 0.048). When the system was free of CuSO4 and vitamin C, CS2 also induced the emission of chemiluminescence intensity. We conclude from these results that CS2 can induce the phenanthroline chemiluminescence system to generate hydroxyl radicals and advance the peak time, and that thiourea can inhibit the effect. The mechanism may be explained by a catalytic effect of CS2 directly on H2O2.

Carbon disulfide nephropathy

A 45-year-old nondiabetic man presented with features resembling diabetic triopathy. He worked in a rayon manufacturing plant and was exposed to toxic levels of carbon disulfide (CS(2)). Clinical abnormalities included peripheral and central nervous system abnormalities as well as retinopathy, dyslipidemia, cardiovascular disease, and nephrotic syndrome. He later developed focal sclerosing glomerulonephritis. The latter has not previously been described in cases of CS(2) exposure. Terminally, he developed end-stage renal disease and progressive dementia, both of which were thought to be consequences of CS(2) exposure earlier in life.

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.