CS2 Exposure Research Articles

Mitochondrial transfer of α-synuclein mediates carbon disulfide-induced mitochondrial dysfunction and neurotoxicity

Exposure to carbon disulfide (CS2) is a recognized risk factor in the pathogenesis of Parkinson’s disease, yet the underlying mechanisms of deleterious effects on mitochondrial integrity have remained elusive. Here, through establishing CS2 exposure models in rat and SH-SY5Y cells, we demonstrated that highly expressed α-synuclein (α-Syn) is transferred to mitochondria via membrane proteins such as Tom20 and leads to mitochondrial dysfunction and mitochondrial oxidative stress, which ultimately causes neuronal injury. We first found significant mitochondrial damage and oxidative stress in CS2-exposed rat midbrain and SH-SY5Y cells and showed that mitochondrial oxidative stress was the main factor of mitochondrial damage by Mitoquinone intervention. Further experiments revealed that CS2 exposure led to the accumulation of α-Syn in mitochondria and that α-Syn co-immunoprecipitated with mitochondrial membrane proteins. Finally, the use of an α-Syn inhibitor (ELN484228) and small interfering RNA (siRNA) effectively mitigated the accumulation of α-Syn in neurons, as well as the inhibition of mitochondrial membrane potential, caused by CS2 exposure. In conclusion, our study identifies the translocation of α-Syn to mitochondria and the impairment of mitochondrial function, which has important implications for the broader understanding and treatment of neurodegenerative diseases associated with environmental toxins.

Luminescent metal-organic framework sensor for detection of biomarker 2-thiothiazolidine-4-carboxylic acid

Using terephthalic acid (BDC) as the organic ligand and zirconium chloride (ZrCl4) as the metal source, a lanthanide metal-organic framework (Tb/Zr-UiO-66) with excellent luminescence properties was successfully prepared by introducing the lanthanide ion Tb3+in situ through a simple one-pot hydrothermal reaction, which was designed as an optical biosensor for 2-thiothiazolidine-4-carboxylic acid (TTCA), the urinary biomarker of human exposure to carbon disulfide (CS2). The fabricated Tb/Zr-UiO-66 exhibits high chemical and luminescent stability, making it competent for recognizing TTCA in aqueous environments. Significantly, its luminescence intensity change shows a good linearity relationship with the concentration of TTCA in the range of 0–110 µM, with a limit of detection (LOD) as low as 0.14 µM. Meanwhile, this sensor exhibits good selectivity and anti-interference ability towards TTCA among the various coexisting components in urine (Na+, K+, NH4+, SO42−, Cl −, creatine, creatinine, glucose, urea, etc.), and can quickly respond to TTCA within 2 min. The analysis results of powder X-ray diffraction (PXRD), fluorescence lifetime and ultraviolet–visible (UV–vis) spectrum demonstrate that the sensing mechanism can be ascribed to the competition absorption effect between TCAA and Tb/Zr-UiO-66. This biosensor with simple synthesis, stable framework, high sensitivity and selectivity, and rapid response has potential to become a powerful tool for diagnosing diseases associated with CS2 exposure.

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, invitro and invivo 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.

Carbon disulfide exposure induced lung function reduction partly through oxidative protein damage: A cross-sectional and longitudinal analysis

Carbon disulfide (CS2) exposure has been associated with lung function reduction in occupational population. However, evidence on the general population with relatively low CS2 exposure is lacking and the mechanism involved remains largely unknown. Urinary CS2 metabolite (2-mercaptothiazolidine-4-carboxylic acid, TTCA) and lung function were determined in the urban adults from the Wuhan-Zhuhai cohort at baseline in 2011–2012 and were repeated every 3 years. Cross-sectional and longitudinal associations between TTCA and lung function were estimated using linear mixed models. Inflammation and oxidative damage biomarkers in blood/urine were measured to evaluate their potential mediating roles involved. Cross-sectionally, participants in the highest quartile of TTCA level showed a 0.64% reduction in FEV1/FVC and a −308.22 mL/s reduction in PEF, compared to those in the lowest quartile. Longitudinally, participants with consistently high TTCA level had annually −90.27 mL/s decline in PEF, compared to those with consistently low TTCA level. Mediation analysis revealed that plasma protein carbonyl mediated 49.89% and 22.10% of TTCA-associated FEV1/FVC and PEF reductions, respectively. Conclusively, there was a cross-sectional and longitudinal association between CS2 exposure and lung function reduction in the general urban adults, and protein carbonylation (oxidative protein damage) partly mediated lung function reduction from CS2 exposure.

Health Behavior and Health Condition of Patients Exposed to Carbon Disulfide according to Exposure Level

Objective The purpose of this study is to garner useful information through a comparative analysis of health behaviors and health status between the low-dose carbon disulfide (CS2) exposure patients and the high-dose CS2 exposure patients. Methods Among 910 retired workers who were recognized for carbon disulfide poisoning, 702 survived at the research period. A total of 596 people were selected for the study, except 106 people who refused to participate or were unable to express their opinions. We define the low-dose exposure group as those under 5 ppm, and the high-dose exposure group as those over 5 ppm. Results Compared with the low-dose exposure patient, the high-dose exposure patient had a more frequent awakening during sleep and difficulty of dressing, toileting bathing, and food preparation. The high-dose exposure patient was vulnerable to anxiety and memory. In addition, the high-dose exposure patient felt hopeless more. The high-dose exposure patient lagged behind the low-dose exposure patient in sleep time and sleep quality. Conclusion The vulnerability of the high-dose exposure patient in terms of mental and sleep health needs to be acknowledged as the various characteristics of the CS2 exposure patient that appears according to an exposure group. A variety of disease prevention and health promotion programs that focus on the health behavior and status of the low-dose exposure and the high-dose exposure patients need to be developed and put into practice. Key words: Carbon disulfide exposure; Health behavior; Sleep; Activities of daily living; Instrumental activities of daily living; Mental health

Associations of urinary carbon disulfide metabolite with oxidative stress, plasma glucose and risk of diabetes among urban adults in China.

Carbon disulfide (CS2) has been reported to induce disorder of glucose metabolism. However, the associations of CS2 exposure with plasma glucose levels and risk of diabetes have not been explored in general population, and the underlying mechanisms remain unclear. We aim to examine the relationships between CS2 exposure and fasting plasma glucose (FPG) levels, as well as diabetes, and assess the potential role of oxidative stress among the abovementioned relationships in Chinese general adults. The concentrations of urinary biomarkers of CS2 exposure (2-thiothiazolidin-4-carboxylic acid, TTCA), and biomarkers for lipid peroxidation (8-isoprostane, 8-iso-PGF2α) and DNA oxidative damage (8-oxo-7,8-dihydro-20-deoxyguanosine, 8-OHdG) were measured among 3338 urban adults from the Wuhan-Zhuhai cohort. Additionally, FPG levels were tested promptly. Generalized linear models and logistic regression models were used to quantify the associations among urinary TTCA, oxidative damage markers, FPG levels and diabetes risk. Mediation analysis was employed to estimate the role of oxidative damage markers in the association between urinary TTCA and FPG levels. We discovered a significant relationship between urinary TTCA and FPG levels with regression coefficient of 0.080 (95% CI: 0.002,0.157). Besides, the risk of diabetes was positively related to urinary TTCA (OR:1.282, 95% CI: 1.055,1.558), particularly among those who did not exercise regularly. Each 1% increase of urinary TTCA concentration was associated with a 0.096% and 0.037% increase in urinary 8-iso-PGF2α and 8-OHdG, respectively. Moreover, we found an upward trend of FPG level as urinary 8-iso-PGF2α gradually increased (Ptrend<0.05), and urinary 8-iso-PGF2α mediated 21.12% of the urinary TTCA-associated FPG increment. Our findings indicated that urinary CS2 metabolite was associated with increased FPG levels and diabetes risk in general population. Lipid peroxidation partly mediated the association of urinary CS2 metabolite with FPG levels.

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

BackgroundCarbon 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.MethodsRats 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.ResultsThe 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.ConclusionThese 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.

Carbon disulfide induced decidualization disorder in the mice uterus at the window of implantation.

Carbon disulfide (CS2) is regarded as a common occupational poison that is widely used in the textile industry in China. Our previous research suggests that CS2 can induce significant implantation disorders in pregnant mice; however, the specific mechanism remains unclear. Uterine conception in mice must undergo decidualization, which is the prerequisite for propitious blastocyst implantation into the endometrium. Therefore, in this study, we established models of pregnant mice to explore the toxic effects of CS2 on decidualization to elucidate the basic mechanism of implantation disorder after CS2 exposure. The uterine tissues were immediately collected according to the predetermined endpoints to measure the expression levels of IGFBP1 and PRL (markers of decidualization differentiation), IL-11 (representing the secretory function of decidual cells), AKT and pAKT by western blotting, RT-PCR, immunohistochemical staining, H&E staining and ELISA. N-carbamoyl glutamic acid (NCG) acted as an agonist of AKT to verify the upstream regulatory mechanism of decidualization disorder by CS2. The results showed that the normal reaction of decidual transformation was obviously disrupted by CS2 upon 3.5 dpc and 4.5 dpc exposure. The blastocyst did not adhere to the epithelium after 3.5 dpc-exposure and did not invade the endometrium after 4.5 dpc-exposure, resulting in its suspension in the uterine cavity, stagnation and eventual loss. The proteins expression levels were decreased by 95.2% for IGFBP1 and 76.2% for PRL at the 4.5 dpc endpoint after 3.5 dpc CS2 exposure compared with the control. Simultaneously, the mRNA and protein expression levels of IL-11 in uterine tissues were significantly reduced by CS2, and consistent decreasing trends over time were observed for IGFBP1 and PRL, compared with the control. Additionally, the ratio of pAKT/AKT protein expression was decreased by 72.2% and 94.8% at 12h and 18h after 3.5 dpc exposure and by 53.3% and 74.3% at 6h and 12h after 4.5 dpc exposure, respectively, compared with the corresponding controls. Furthermore, NCG could recover the IGFBP1 and PRL protein expression, which was increased by 27.5% and 52.3% at 4.5 dpc and 6.5 dpc, respectively, after 3.5 dpc exposure for IGFBP1 and by 30.3% at 6.5 dpc after 4.5 dpc exposure for PRL, compared with CS2 exposure alone. Collectively, this study suggested that the decidualization disorder caused by CS2 at the window of implantation in pregnant mice, which is triggered by pAKT, contributed to the implantation disorder and eventually led to embryo loss. It is worth noting that our study may provide a new perspective and reference for exploring the toxic mechanism of implantation disorder and even infertility in harmful circumstances.

Carbon Disulfide Induces Embryo Implantation Disorder by Disturbing the Polarization of Macrophages in Mice Uteri.

Carbon disulfide (CS2) induces embryo implantation disorders. Macrophages participate in the process of pregnancy. Therefore, we want to explore the effects of CS2 exposure on polarization and immune function of macrophages in pregnant mice uteri. The exposure times were gestation days 3 (GD3), 4 (GD4), and 5 (GD5), and the observation end points were arranged in a time series after CS2 exposure. The uterine tissues were collected to detect the expression levels of macrophages cytokines (IL-6, IL-12, TGF-β1, and Vegf-a) and downstream regulatory cytokines of Th1-type (IL-2 and IFN-γ) and Th2-type (IL-10 and IL-4) by flow cytometry, ELISA, and q-PCR. The results showed that, compared with the controls, the ratios of M1/M2 macrophages in the endometrium significantly increased by 96%, 110%, and 177% at the GD4, GD6, and GD7 observation end points after GD3 exposure and increased about 3.88-fold and 2.37-fold at the GD6 and GD7 observation end points after GD4 exposure, respectively. In contrast, the ratio of M1 and M2 macrophages significantly reduced by 53% at the GD5 observation end point after GD3 exposure. Meanwhile, the expression levels of IL-6 were significantly increased about 2.00-fold for mRNA and 1.60-fold for protein at GD4 observation end points after GD3 exposure, and the mRNA levels of IL-12 increased about 3.61-fold at the GD6 observation end points after GD4 exposure. The mRNA levels of TGF-β1 were significantly decreased by 41%, 25%, and 20% at the GD7 observation end points after exposure at GD3, GD4, and GD5, and the expression levels of Vegf-a mRNA and protein were decreased. Furthermore, the ratio of IL-2/IL4, IL-2/IL-10, IFN-γ/IL-4, and IFN-γ/IL-10 in the uterine tissue was significantly increased at the exposure groups. These findings suggest that the imbalanced polarization of macrophages is the key regulator in the progress of CS2-induced embryo loss.

The suppressed autophagy induced by carbon disulfide could be rescued by N-carbamoyl glutamate during the window of embryo implantation in mice

ObjectivesTo explore the effects of carbon disulfide (CS2) and N-carbamoyl glutamate (NCG) on autophagy during the window of embryo implantation in mice and whether dietary NCG supplementation can promote embryo implantation in case of CS2 exposure. MethodsPregnant mice that received single intraperitoneal injection of CS2 on Gestational day (GD)4 were fed basal diet with or without NCG supplementation from GD1 to endpoints. The control mice were injected solvents. There were four endpoints (GD5, GD6, GD7 and GD9 endpoints) in each group. The uterus was collected on endpoints to detect autophagy-related markers by using the methods of transmission electron microscopy (TEM), immunohistochemistry (IHC), quantitative real-time polymerase chain reaction (qRT-PCR) and ELISA. ResultsThe P62 brown punctate staining increased in CS2 exposure group and reduced after dietary NCG supplementation, which was opposite with LC3B, Beclin1 and ATG5 on GD5 endpoint. Simultaneously, P62 protein expression raised 43.33% on GD5 endpoint (p < 0.01) when exposed to CS2 and descended to the control level after NCG supplementation. The rate of decline of LC3B and Beclin1 proteins were 27.04% (p < 0.01) and 23.27% (p < 0.05) on GD5 endpoint, 20.20% (p < 0.05) and 11.30% on GD7 endpoint in CS2 exposure group, respectively, then NCG supplementation caused the LC3B and Beclin1 protein expression to rise in different degrees. Comparatively, the mRNA expression of all autophagy-related gene changed more apparently on three endpoints than the protein expression. The images of TEM showed that nearly no autophagosome could be seen in CS2 exposure group, while dietary NCG supplementation increased the number of autophagosome obviously on GD5 endpoint. The number of implanted embryos which declined due to CS2 exposure returned to normal in NCG supplementation group. ConclusionsDietary NCG supplementation could rescue the suppressed autophagy induced by CS2 in the window of implantation and increase the number of implanted embryos.

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.

Carbon disulfide exposure estimate and prevalence of chronic diseases after carbon disulfide poisoning-related occupational diseases

BackgroundIn Korea, Carbon disulfide (CS2) toxicity was an important social problem from the late 1980s to the early 1990s but there have been few large-scale studies examining the prevalence of diseases after CS2 exposure discontinuance. So we investigated past working exposure to CS2 characteristics from surviving ex-workers of a rayon manufacturing plant including cumulative CS2 exposure index. Furthermore, we studied the prevalence of their chronic diseases recently after many years.MethodsWe interviewed 633 ex-workers identified as CS2 poisoning-related occupational diseases to determine demographic and occupational characteristics and reviewed their medical records. The work environment measurement data from 1992 was used as a reference. Based on the interviews and foreign measurement documents, weights were assigned to the reference concentrations followed by calculation of individual exposure index, the sum of the portion of each time period multiplied by the concentrations of CS2 during that period.ResultsThe cumulative exposure index was 128.2 ppm on average. Workers from the spinning, electrical equipment repair, and motor repair departments were exposed to high concentrations of ≥10 ppm. Workers from the maintenance of the ejector, manufacturing of CS2, post-process, refining, maintenance and manufacturing of viscose departments were exposed to low concentrations below 10 ppm. The prevalence for hypertension, coronary artery disease, cerebrovascular disease, diabetes, arrhythmia, psychoneurotic disorder, disorders of the nervous system and sensory organ were 69.2%, 13.9%, 24.8%, 24.5%, 1.3%, 65.7%, 72.4% respectively.ConclusionsWe estimated the individual cumulative CS2 exposure based on interviews and foreign measurement documents, and work environment measurement data. Comparing the work environment measurement data from 1992, these values were similar to them. After identified as CS2 poisoning, there are subjects over 70 years of average age with disorders of the nervous system and sensory organs, hypertension, psychoneurotic disorder, cerebrovascular disease, diabetes, coronary artery disease, and arrhythmia. Because among ex-workers of the rayon manufacturing plant, only 633 survivors recognized as CS2 poisoning were studied, the others not identified as CS2 poisoning should also be investigated in the future.

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

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

Carbon disulfide potentiates the effects of impulse noise on the organ of Corti

Occupational noise can damage workers’ hearing, and the phenomenon is even more dangerous when noise is associated with an ototoxic solvent. Aromatic solvents are known to provoke chemical-induced hearing loss, but little is known about the effects on hearing of carbon disulfide (CS2) when combined with noise. Co-exposure to CS2 and noise may have a harmful effect on hearing, but the mechanisms involved are not well understood. For instance, CS2 is not thought to have a cochleotoxic effect, but rather it is thought to cause retrocochlear hearing impairment. In other words, CS2 could have a distal neuropathic effect on the auditory pathway. However, a possible pharmacological effect of CS2 on the central nervous system (CNS) has never been mentioned in the literature. The aim of this study was to assess, in rats, the effects of a noise (continuous vs. impulse), associated with a low concentration of CS2 [(short-term threshold limit value) x 10 as a safety factor] on the peripheral auditory receptor. The noise, whatever its nature, was an octave band noise centered at 8kHz, and the 250-ppm CS2 exposure lasted 15min per hour, 6h per day, for 5 consecutive days. The impact of the different experimental conditions on hearing loss was assessed using distortion product oto-acoustic emissions and histological analyses. Although the LEX,8h (8-h time-weighted average exposure) for the impulse noise was lower (84dB SPL) than that for the continuous noise (89dB SPL), it appeared more damaging to the organ of Corti, in particular to the outer hair cells. CS2 exposure alone did not have any effect on the organ of Corti, but co-exposure to continuous noise with CS2 was less damaging than exposure to continuous noise alone. In contrast, the cochleo-traumatic effects of impulse noise were significantly enhanced by co-exposure to CS2.Therefore, CS2 can clearly modulate the middle-ear reflex function. In fact, CS2 may have two distinct effects: firstly, it has a pharmacological effect on the CNS, modifying the trigger of the acoustic reflex; and secondly, it can make the organ of Corti more susceptible to impulse noise. The pharmacological effects on the CNS and the effects of CS2 on the organ of Corti are discussed to try to explain the overall effect of the solvent on hearing. Once again, the results reported in this article show that the temporal structure (continuous vs. impulse) of noise should be taken into consideration as a key parameter when establishing hearing conservation regulations.

The Effects of Occupational Exposure of Carbon Disulfide on Sexual Hormones and Semen Quality of Male Workers From a Chemical Fiber Factory.

This study is aimed to analyze the relationship between occupational CS2 exposure and reproductive impairments. Seventy-six CS2-exposed (9.73 ± 2.76 mg/m(3)) male workers and 94 unexposed workers were selected for study. Worker demographics were assessed with a customized questionnaire. Sexual hormones and sperm-related parameters were measured by biochemical or morphological analysis. The CS2-exposed workers had significantly higher serum levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and lower levels of testosterone (T). Significant decrements were also identified in sperm viability and motility, chromatin, antioxidant capacity, mitochondrial membrane potential, mitochondrial membrane permeability transition pore (MPTP), and respiratory chain Complexes II and IV. Our data indicated that occupational CS2 exposure can exert deleterious effects on male sexual hormones and sperm quality, and mitochondrial dysfunction may play a vital role in this process.

No evidence of cardiovascular toxicity in workers exposed below 5ppm carbon disulfide.

Carbon disulfide (CS2), used in the viscose process, is well known for having multiple health effects, including on the cardiovascular system, in workers with long-term exposure higher than 10ppm. The mechanisms of those effects are, however, not precisely defined, and it remains uncertain whether cardiovascular toxicity may occur at exposure levels lower than 10ppm. Therefore, the purpose of this study is to explore the health impact of low CS2 exposure levels using an array of preclinical biomarkers of cardiovascular risk. Exposure intensity was determined by measuring urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) in 117 workers from two plants using the viscose process, sampled in multiples phases (2003, 2006 and 2013). A cumulative exposure index (CEI) and a recent exposure index (REI) were calculated for each worker, and shiftwork was documented to account for potential confounding. Cardiovascular parameters included blood pressure, total, LDL and HDL cholesterol, triglycerides, C-reactive protein dosed in serum with high sensitivity (HsCRP), N-terminal pro-brain natriuretic peptide, and albuminuria/creatininuria ratio (UACR). Potential biological confounders were fasting blood glucose and serum creatinine. Bivariate and multivariate regression analyses were used to trace relationships between cardiovascular risk biomarkers and other variables, including CEI, REI and shiftwork duration. Median REI and CEI were 0.05mg TTCA/g creat and 21.5mg TTCA/g creat*months, respectively. While expected associations, such as between HsCRP and LDL Cholesterol, were found, significant associations between cardiovascular risk markers and CS2 exposure indexes (CEI or REI) were not detected. Shiftwork duration was positively associated with UACR in workers with elevated fasting blood glucose. In practice, when CS2 exposure levels are kept below 5ppm (TTCA<2.2mg/g creat), it does not appear useful to perform a systematic monitoring of total serum cholesterol or its subfractions, or of the new biomarkers of cardiovascular risk (NTproBNP, HsCRP, UACR) investigated in the present study. It appears important to carefully monitor the existence of diabetes that may justify avoiding shiftwork.

Increased intima-media thickness in rayon workers after long-term exposure to carbon disulfide.

Long-term exposure to carbon disulfide (CS2) is associated with increased cardiovascular mortality. However, previous studies on actual vascular changes showed heterogeneous results. Intima-media thickness of the carotid arteries (IMT) represents an established marker of atherosclerosis and a reasonable surrogate marker for cardiovascular risk. IMT was examined in a large cohort of CS2 exposed workers and the association with cumulative CS2 exposure analysed. In a cross-sectional examination, 290 exposed and 137 non-exposed workers in a German rayon-manufacturing plant were assessed. Individual cumulative exposure was calculated from this assessment combined with the results of two cross-sectional studies in 1992 and 1999 and department-specific annual means of ambient (CECS2) and individual biological (CETTCA) monitoring results obtained 1992-2009. Furthermore, cumulative duration of working in CS2-exposed departments (CEYEARS) was calculated. Examination included assessment of a broad set of known cardiovascular risk factors and IMT measurement of the carotid arteries on both sides. Multiple linear regression analyses were performed with IMT as outcome and three variants of cumulative exposure (duration of exposure, cumulative CS2, and cumulative TTCA) as well as categorised maximum CS2 exposure, all adjusted for cardiovascular risk factors. All models of cumulative exposure showed a significant increase in IMT in the group with the highest level of exposure: CEYEARS > 20 years, β = 0.045 mm; CECS2 > 270 ppm × years, β = 0.052 mm; CETTCA > 33 mg/g creatinine × years, β = 0.038 mm. Alternatively, addressing maximum exposure, workers with CS2 exposure of >10 ppm in at least 3 years exhibited a significant IMT increase (β = 0.068 mm). Long-term CS2 exposure is an independent risk factor concerning IMT changes. The amount of IMT increase, in a similar range as that associated with other cardiovascular risk factors, might be clinically relevant.

Down-regulation of uterine LIF expression induced by the hormonal level disorder causes embryo implantation loss after mice exposed to carbon disulfide at peri-implantation

Carbon disulfide (CS2) exposure can cause embryo implantation loss but the mechanism remains unclear. Earlier study revealed that the 4th day of gestation (GD4) and GD5 were the most sensitive exposure time on which the number of implanted embryos decreased obviously in mice. Leukemia inhibitory factor (LIF) in maternal uterine tissue is involved in embryo implantation, which is produced by endometrium and Th2 cells that participate in cellular adhesion of maternal–fetal interface. We herein investigated the effect of CS2 on the expression of LIF in uterine tissue and its regulatory mechanism in Kunming mice. Exposure was on GD3, GD4, GD5 and GD6, respectively, single administration (631.4 mg/kg), and the indexes were arranged in time series after exposure. The results showed that LIF gene breakage was captured at the 18th hour after exposure by Comet-FISH and the protein and mRNA of LIF in uterine tissue were down-regulated after exposure through the peri-implantation period. In addition, sex steroid hormones, progesterone (P4) and oestrogen (E2) were detected since they can stimulate synthesis of LIF from endometrial cells. Results showed that P4 and E2 in serum were down-regulated at all the endpoints of CS2 exposure groups. These findings suggested that the down-regulated LIF induced by the decreased P4 and E2 after mice exposure to CS2 might be important reasons for implantation disorders.

Carbon disulfide induces rat testicular injury via mitochondrial apoptotic pathway

Carbon disulfide (CS2), one of the most important volatile organic chemicals, was shown to have serious impairment to male reproductive system. But the underline mechanism is still unclear. In the present study, we aim to investigate the male germ cell apoptosis induced by CS2 exposure alone and by co-administration with cyclosporin A (CsA), which is the inhibitor of membrane permeability transition pore (MPTP). It was shown that CS2 exposure impaired ultrastructure of germ cells, increased the numbers of apoptotic germ cells, accumulated intracellular level of calcium, elevated ROS level, and increased activities of complexes of respiratory chain. Meanwhile, exposure to CS2 dramatically decreased the mitochondrial transmembrane potential (ΔΨm) and levels of ATP and MPTP opening. Exposure to CS2 can also cause a significantly dose-dependent increase in the expression levels of Bax, Cytc, Caspase-9, and Caspase-3, but decreased the expression level of Bcl-2. Moreover, co-administration of CsA with CS2 can reverse or alleviate the above apoptotic damage effects of CS2 on testicular germ cells. Taken together, our findings suggested that CS2 can cause damage to testicular germ cells via mitochondrial apoptotic pathway, and MPTP play a crucial role in this process.

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

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. 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. 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). 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.