A review of health effects of carbon disulfide in viscose industry and a proposal for an occupational exposure limit

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.

Environmental exposure to industrial air pollution is associated with decreased male fertility

OBJECTIVE

To understand how chronic exposure to industrial air pollution is associated with male fertility through semen parameters.

DESIGN

Retrospective cohort study.

PATIENTS

Men in the Subfertility, Health, and Assisted Reproduction cohort who underwent a semen analysis in the two largest healthcare systems in Utah from 2005-2017 with ≥1 measured semen parameter (N = 21,563).

INTERVENTION(S)

Residential histories for each man were constructed using locations from administrative records linked through the Utah Population Database. Industrial facilities with air emissions of nine endocrine-disrupting compound chemical classes were identified from the Environmental Protection Agency Risk-Screening Environmental Indicators microdata. Chemical levels were linked with residential histories for the 5 years before each semen analysis.

MAIN OUTCOME MEASURES

Semen analyses were classified as azoospermic or oligozoospermic (< 15 M/mL) using World Health Organization cutoffs for concentration. Bulk semen parameters such as concentration, total count, ejaculate volume, total motility, total motile count, and total progressive motile count were also measured. Multivariable regression models with robust standard errors were used to associate exposure quartiles for each of the nine chemical classes with each semen parameter, adjusting for age, race, and ethnicity, as well as neighborhood socioeconomic disadvantage.

RESULTS

After adjustment for demographic covariates, several chemical classes were associated with azoospermia and decreased total motility and volume. For exposure in the 4th relative to 1st quartile, significant associations were observed for acrylonitrile (βtotal motility = -0.87 pp), aromatic hydrocarbons (odds ratio [OR]azoospermia = 1.53; βvolume = -0.14 mL), dioxins (ORazoospermia = 1.31; βvolume = -0.09 mL; βtotal motility = -2.65 pp), heavy metals (βtotal motility = -2.78pp), organic solvents (ORazoospermia = 1.75; βvolume = -0.10 mL), organochlorines (ORazoospermia = 2.09; βvolume = -0.12 mL), phthalates (ORazoospermia = 1.44; βvolume = -0.09 mL; βtotal motility = -1.21 pp), and silver particles (ORazoospermia = 1.64; βvolume = -0.11 mL). All semen parameters significantly decreased with increasing socioeconomic disadvantage. Men who lived in the most disadvantaged areas had concentration, volume, and total motility of 6.70 M/mL, 0.13 mL, and 1.79 pp lower, respectively. Count, motile count, and total progressive motile count all decreased by 30-34 M.

CONCLUSION(S)

Several significant associations between chronic low-level environmental exposure to endocrine-disrupting compound air pollution from industrial sources and semen parameters were observed. The strongest associations were seen for increased odds of azoospermia and declines in total motility and volume. More research is needed to further explore additional social and exposure factors as well as expand on the risk posed to male reproductive health by the studied chemicals.

Thiram induces myocardial oxidative damage and apoptosis in broilers via interfering their cardiac metabolism

Thiram is a dithiocarbamate pesticide extensively used as a fungicide to preserve crops and seeds. Long-term exposure to thiram causes potential harm to the health of human beings and animals. So far, most of the researches on thiram focused on erythrocyte toxicity, immune system, kidney damage, and tibial dyschondroplasia; however, there is less data on cardiac toxicity. In this study, we examined cardiac histopathology, inflammatory factors, oxidative stress indicators, and apoptosis markers in the heart of broilers that were exposed to thiram. According to our findings, the continuous exposure to thiram caused pathological changes and abnormal function of myocardial tissues with increased level of inducible nitric oxide synthase (iNOS), inflammatory factors (IL-6, IL-8, TNF-α and NF-κB), and decreased level of anti-inflammatory factor (IL-10). In addition, thiram significantly upregulated the protein expression of cleaved-caspase 3, cleaved-PARP, and caused cardiomyocyte apoptosis. Meanwhile, the expression of heat shock proteins (HSP60, HSP70, HSP90) markedly decreased in the thiram-treated groups. An excessive accumulation of peroxidation products (MDA, H₂O₂), a decrease in T-AOC, and antioxidant activity enzymes (T-SOD, GST and GPX) were also noticed, all of which led to oxidative stress and activation of Nrf2 signal pathway by up-regulating key target genes (HO-1 and SODs). Thiram-induced metabolites were further identified via non-targeted metabonomic analysis. Correlation analysis revealed eighteen differentially expressed metabolites, closely related to cardiac injury. Importantly, thiram primarily affected the taurine and hypotaurine metabolism, pyrimidine metabolism as well as glycerol metabolism. Collectively, our study suggests that thiram could cause cardiotoxicity by interfering with taurine and hypotaurine metabolism, pyrimidine metabolism, and glycerolipid metabolism, which further induce oxidative stress via triggering Nrf2 signal pathway. This study may provide new evidence for the molecular mechanism of cardiotoxicity caused by thiram and resonate the alarm for animals and workers who have been exposed to thiram for a long time.

Environmental monitoring and health assessment in an industrial town in central India: A cross-sectional study protocol

Background

Textile industry has been widely implicated in environmental pollution. The health effects of residing near manufacturing industries are not well documented in India, especially in central India. Hence, a cross-sectional environmental monitoring and health assessment study was initiated as per directions of the local authorities.

Methods

Comprehensive exposure data about the concentrations of relevant pollutants in the ambient air and ground water samples in the study area will be collected over one year. Using stratified random sampling, 3003 apparently healthy adults will be selected from the study area. Sociodemographic and anthropometric information, relevant medical and family history, and investigations including spirometry, electrocardiogram, neurobehavioral tests, and laboratory investigations (complete blood count, lipid profile and random blood glucose) will be conducted. Finally Iodine azide test and heavy metal level detection in urine and blood samples respectively will be conducted in a subset of selected participants to assess individual pollution exposure. Ethics approval has been obtained from the Institutional Ethics Committee of the National Institute for Research in Environmental Health (No: NIREH/IEC-7-II/1027, dated 07/01/2021).

Discussion

This manuscript describes the protocol for a multi-disciplinary study that aims to conduct environmental monitoring and health assessment in residential areas near viscose rayon and associated chemical manufacturing industries. Although India is the second largest manufacturer of rayon, next only to China, and viscose rayon manufacturing has been documented to be a source of multiple toxic pollutants, there is a lack of comprehensive information about the health effects of residing near such manufacturing units in India. Therefore implementing this study protocol will aid in filling in this knowledge gap.

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

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

Measurement of CS2 Absorption Cross-Sections in the 188-215 nm Region at Room Temperature and Atmospheric Pressure

Carbon disulfide, an important sulfur-containing species, has strong absorption lines in the wavelength range of 188 nm to 215 nm. It is difficult to accurately measure the absorption cross sections of carbon disulfide because carbon disulfide will be easily converted into carbon sulfide when it is exposed to ultraviolet light. In this study, the absorption cross sections of carbon disulfide were measured by reducing carbon disulfide conversion. The factors affecting carbon disulfide conversion, including gas flow rate, ultraviolet light intensity, and duration of illumination, were studied to reduce the conversion of carbon disulfide by controlling experimental conditions in the experiment. Finally, the absorption cross sections of carbon disulfide at room temperature and atmospheric pressure were calculated using the absorption spectrum and the carbon disulfide concentration in the absence of carbon disulfide conversion. The wavelengths of 16 absorption peaks on the carbon disulfide absorption cross sections of the vibration change were marked. Carbon disulfide has the maximum absorption cross section of 4.5 × 10^-16 cm²/molecule at a wavelength of 198.10 nm.

Hunting for Toxic Industrial Chemicals: Real-Time Detection of Carbon Disulfide Traces by Means of Ion Mobility Spectrometry

Sensitive real-time detection of vapors produced by toxic industrial chemicals (TICs) represents a stringent priority nowadays. Carbon disulfide (CS₂) is such a chemical, being widely used in manufacturing synthetic textile fibers and as a solvent. CS₂ is simultaneously a very reactive, highly flammable, irritant, corrosive, and highly toxic compound, affecting the central nervous system, cardiovascular system, eyes, kidneys, liver, skin, and reproductive system. This study was directed towards quick detection and quantification of CS₂ in air, using time-of-flight ion mobility spectrometry (IMS); photoionization detection (PID) was also used as confirmatory technique. Results obtained indicated that IMS can detect CS₂ at trace levels in air. The ion mobility spectrometric response was in the negative ion mode and presented one product ion, at a reduced ion mobility (K₀) of 2.25 cm² V⁻¹ s⁻¹. Our study demonstrated that by using a portable, commercial IMS system (model Mini IMS, I.U.T. GmbH Berlin Germany) one can easily measure CS₂ at concentrations of 0.1 ppm_v (0.3 mg m⁻³) in the negative ion mode, which is below the lowest threshold value of 1 ppm_v given for industrial hygiene. A limit of detection (LOD) of ca. 30 ppb_v (0.1 mg m⁻³) was also estimated.

Renal injury following long-term exposure to carbon disulfide: analysis of a case series

Background

To investigate the clinicopathological characteristics of renal damage caused by long-term exposure to carbon disulfide (CS2) in nine patients.

Methods

All the patients underwent ultrasound-guided renal biopsy. All specimens were examined by light microscopy and immunohistochemistry (IHC). Samples form one patient were further analyzed using transmission electron microscopy.

Results

Similar pathological changes were observed in all patients, but the degrees of lesions were different. All cases had moderate to severe nodular mesangial hyperplasia; among these, type “Kimme1stie1-Wi1son” (K-W nodule for short) was observed in four cases, type “K - W nodule” refer to nodular hyperplasia of mesangial membrane like letter K or W. four cases had proliferative extracapillary glomerulonephritis (GN), while there were no concomitant changes in one patient. Besides, six cases had diffuse basement membrane thickening, focal segmental sclerosis or bulbar sclerosis; two cases had diffuse glomerular sclerosis, and one case had focal segmental capillary hyperplasia. Moreover, all patients had renal tubular atrophy/interstitial fibrosis with less to moderate chronic inflammatory cell infiltration, as well as renal arteriosclerosis. IHC showed that the depositions of IgA, IgM, C3d, C4d, C1q and Fib were not specific; while IgG, type III collagen, Fibronectin, Amyloid A, Igκ, Igλ, HBsAg and HBcAg were all negative.

Conclusion

Diffuse nodular mesangial hyperplasia/sclerosing glomerular nephropathy is characterized by nodular mesangial hyperplasia with type “K-W nodules” formation, which we speculate is a special pathological manifestation of renal damage caused by carbon disulfide (CS2).

Thiocarbonyl Surrogate via Combination of Potassium Sulfide and Chloroform for Dithiocarbamate Construction

An efficient and practical thiocarbonyl surrogate via combination of potassium sulfide and chloroform was established. A variety of dithiocarbamates were afforded along with four new chemical bond formations in a one-pot reaction in which the thiocarbonyl motif was generated in situ. Furthermore, these readily accessed molecules showed promising activity against HDAC8, opening a potential gateway to discover a new type of nonhydroxamate and isoenzyme-selective HDAC inhibitors.

System for simultaneous sensing of sulfur dioxide and carbon disulfide based on deep ultraviolet absorption spectroscopy

In this study, a sensitive system for simultaneous sensing of sulfur dioxide and carbon disulfide was developed based on absorption spectroscopy in the deep ultraviolet. An effective spectrum-unfolding approach is proposed to examine the overlapping spectral characteristics. Direct proportional relations with determination coefficients of 0.999 were obtained. The detection limit of sulfur dioxide was determined to be 42 ppb, and a detection limit of 5 ppb for carbon disulfide was achieved with an optical length of 20 cm. The interplay between the measurement results of the two components was investigated. Interference close to the detection limits was confirmed for both sulfur dioxide and carbon disulfide measurements. An automatic and reliable simultaneous sensing system for sulfur dioxide and carbon disulfide was constructed.

H2S and polysulfide metabolism: Conventional and unconventional pathways

It is now well established that hydrogen sulfide (H₂S) is an effector of a wide variety of physiological processes. It is also clear that many of the effects of H₂S are mediated through reactions with cysteine sulfur on regulatory proteins and most of these are not mediated directly by H₂S but require prior oxidation of H₂S and the formation of per- and polysulfides (H₂S_n, n = 2-8). Attendant with understanding the regulatory functions of H₂S and H₂S_n is an appreciation of the mechanisms that control, i.e., both increase and decrease, their production and catabolism. Although a number of standard "conventional" pathways have been described and well characterized, novel "unconventional" pathways are continuously being identified. This review summarizes our current knowledge of both the conventional and unconventional.

Biological Thiols and Carbon Disulfide: The Formation and Decay of Trithiocarbonates under Physiologically Relevant Conditions

Carbon disulfide is an environmental toxin, but there are suggestions in the literature that it may also have regulatory and/or therapeutic roles in mammalian physiology. Thiols or thiolates would be likely biological targets for an electrophile, such as CS₂, and in this context, the present study examines the dynamics of CS₂ reactions with various thiols (RSH) in physiologically relevant near-neutral aqueous media to form the respective trithiocarbonate anions (TTC^-, also known as "thioxanthate anions"). The rates of TTC^- formation are markedly pH-dependent, indicating that the reactive form of RSH is the conjugate base RS^-. The rates of the reverse reaction, that is, decay of TTC^- anions to release CS₂, is pH-independent, with rates roughly antiparallel to the basicities of the RS^- conjugate base. These observations indicate that the rate-limiting step of decay is simple CS₂ dissociation from RS^-, and according to microscopic reversibility, the transition state of TTC^- formation would be simple addition of the RS^- nucleophile to the CS₂ electrophile. At pH 7.4 and 37 °C, cysteine and glutathione react with CS₂ at a similar rate but the trithiocarbonate product undergoes a slow cyclization to give 2-thiothiazolidine-4-carboxylic acid. The potential biological relevance of these observations is briefly discussed.

Uncaging carbon disulfide. Delivery platforms for potential pharmacological applications: a mechanistic approach

We describe the kinetics of the formation and decay of a series of dithiocarbamates under physiological conditions. The goal is to provide a toolbox of compounds that release CS2 by well-defined kinetics in such media. Carbon disulfide is a known environmental toxin, but there is fragmentary evidence suggesting that CS2 may have bioregulatory and/or therapeutic roles in mammalian biology. Further investigation of such roles will require methodologies for controlled delivery of this bioactive small molecule to specific targets. Reported here are mechanistic and computational studies of CS2 release from a series of dithiocarbamate anions (DTCs), where R2N represents several different secondary amido groups. The various DTCs under physiologically relevant conditions show a tremendous range of reactivities toward CS2 dissociation with decay lifetimes ranging from ∼2 s for imidazolidyldithiocarbamate (ImDTC-) to ∼300 s for diisopropyldithiocarbamate (DIDTC-) to >24 h for pyrrolidinyldithiocarbamate (PDTC-) in pH 7.4 phosphate buffer solution at 37 °C. Thus, by making the correct choice of these tools, one can adjust the flux of CS2 in a biological experiment, while the least reactive DTCs could serve as controls for evaluating the potential effects of the dithiocarbamate functionality itself. Kinetics studies and density functional calculations are used to probe the mechanism of DTC- decay. In each case, the rate of CS2 dissociation is acid dependent; however, the DFT studies point to a mechanistic pathway for ImDTC- that is different than those for DIDTC-. The role of general acid catalysis is also briefly probed.

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.

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.

Carbon Disulfide (CS2) Interference in Glucose Metabolism from Unconventional Oil and Gas Extraction and Processing Emissions

Carbon disulfide (CS2) has been historically associated with the manufacturing of rayon, cellophane, and carbon tetrachloride production. This study is one of the first to identify elevated atmospheric levels of CS2 above national background levels and its mechanisms to dysregulate normal glucose metabolism. Interference in glucose metabolism can indirectly cause other complications (diabetes, neurodegenerative disease, and retinopathy), which may be preventable if proper precautions are taken. Rich et al found CS2 and 12 associated sulfide compounds present in the atmosphere in residential areas where unconventional shale oil and gas extraction and processing operations were occurring. Ambient atmospheric concentrations of CS2 ranged from 0.7 parts per billion by volume (ppbv) to 103 ppbv over a continuous 24-hour monitoring period. One-hour ambient atmospheric concentrations ranged from 3.4 ppbv to 504.6 ppbv. Using the U.S. Environmental Protection Agency Urban Air Toxic Monitoring Program study as a baseline comparison for atmospheric CS2 concentrations found in this study, it was determined that CS2 atmospheric levels were consistently elevated in areas where unconventional oil and gas extraction and processing occurred. The mechanisms by which CS2 interferes in normal glucose metabolism by dysregulation of the tryptophan metabolism pathway are presented in this study. The literature review found an increased potential for alteration of normal glucose metabolism in viscose rayon occupational workers exposed to CS2. Occupational workers in the energy extraction industry exposed to CS2 and other sulfide compounds may have an increased potential for glucose metabolism interference, which has been an indicator for diabetogenic effect and other related health impacts. The recommendation of this study is for implementation of regular monitoring of blood glucose levels in CS2-exposed populations as a preventative health measure.

Role of Endoplasmic reticulum apoptotic pathway in testicular Sertoli cells injury induced by Carbon disulfide

The exposure of Carbon disulfide (CS2) is associated with germ cell injury and male infertility in animals and humans. However, the molecular mechanism is currently unknown. This study show here that CS2-induced Sertoli cells injury via Endoplasmic reticulum (ER) apoptotic pathway. SD male rats were exposed to doses of CS2 (0, 50, 250, 1250mgm(-3)) for 4weeks. After treatment, loose structures of seminiferous tubules and disordered cell arrangements were observed by light microscopy. Ultrastructural lesions, deformed chromatins and vacuoles formed from swollen ER were observed by electron microscopy. After primary culture of Sertoli cells, a dose-dependent increased apoptosis were found. The increased activity of Caspase 3, accumulation of intracellular Ca(2+), up-regulation of mRNA and protein expressions of ER apoptotic relative molecules (Calpain 2, Cleaved-Caspase 12, GRP78 and CHOP) were also found in this study. Altogether, our findings indicated that ER apoptotic pathway played an important role in CS2-induced Sertoli cell impairment.

Effect of Skin Protection and Skin Irritation on the Internal Exposure to Carbon Disulfide in Employees of the Viscose Industry

INTRODUCTION

Occupational exposure to carbon disulfide (CS2) leads to inhalative and dermal uptake and thereby to internal exposure. In order to prevent occupational contact dermatitis, gloves and skin protection creams are used at the workplace. The aim of the study was the evaluation of the influence of personal skin protection and irritation on the internal exposure to CS2 of employees in the viscose industry.

METHODS

One hundred and eighty-two male CS2-exposed employees were included in the study and were examined regarding working conditions, use of personal protective measures und skin status. Personal air monitoring and biological monitoring was performed and the 'relative internal exposure' (RIE, internal exposure in relation to external exposure) calculated. A multiple regression analysis calculated the influence of skin protection and irritation on CS2 uptake.

RESULTS

Usage of skin protection creams and gloves (and both in combination) while working was associated with a significantly higher RIE indicating a higher dermal penetration of CS2. Equally, irritated skin and younger age was associated with a higher internal burden.

CONCLUSIONS

Gloves and skin protection creams are useful for preventing occupational skin diseases. However, when handling skin-resorptive substances like CS2, they can increase internal exposure or skin irritation. Therefore, we recommend the careful consideration of benefits and risks of protective creams and gloves at the workplace.

Diversity and ecophysiology of new isolates of extremely acidophilic CS2-converting Acidithiobacillus strains

Biofiltration of industrial carbon disulfide (CS2)-contaminated waste air streams results in the acidification of biofilters and therefore reduced performance, high water use, and increased costs. To address these issues, we isolated 16 extremely acidophilic CS2-converting Acidithiobacillus thiooxidans strains that tolerated up to 6% (vol/vol) sulfuric acid. The ecophysiological properties of five selected strains (2Bp, Sts 4-3, S1p, G8, and BBW1) were compared. These five strains had pH optima between 1 (2Bp) and 2 (S1p). Their affinities for CS2 ranged between 80 (G8) and 130 (2Bp) μM. Strains S1p, G8, and BBW1 had more hydrophobic cell surfaces and produced less extracellular polymeric substance than did strains 2Bp and Sts 4-3. All five strains converted about 80% of the S added as CS2 to S(0) when CS2 was supplied in excess. The rate of S(0) consumption varied between 7 (Sts 4-3) and 63 (S1p) nmol O2 min(-1) ml culture(-1). Low S(0) consumption rates correlated partly with low levels of cell attachment to externally produced S(0) globules. During chemostat growth, the relative amount of CS2 hydrolase in the cell increased with decreasing growth rates. This resulted in more S(0) accumulation during CS2 overloads at low growth rates. Intermittent interruptions of the CS2 supply affected all five strains. Strains S1p, G8, and BBW1 recovered from 24 h of starvation within 4 h, and strains 2Bp and Sts 4-3 recovered within 24 h after CS2 was resupplied. We recommend the use of mixtures of Acidithiobacillus strains in industrial biofilters.

Bacterial CS2 hydrolases from Acidithiobacillus thiooxidans strains are homologous to the archaeal catenane CS2 hydrolase

Carbon disulfide (CS(2)) and carbonyl sulfide (COS) are important in the global sulfur cycle, and CS(2) is used as a solvent in the viscose industry. These compounds can be converted by sulfur-oxidizing bacteria, such as Acidithiobacillus thiooxidans species, to carbon dioxide (CO(2)) and hydrogen sulfide (H2S), a property used in industrial biofiltration of CS(2)-polluted airstreams. We report on the mechanism of bacterial CS(2) conversion in the extremely acidophilic A. thiooxidans strains S1p and G8. The bacterial CS(2) hydrolases were highly abundant. They were purified and found to be homologous to the only other described (archaeal) CS(2) hydrolase from Acidianus strain A1-3, which forms a catenane of two interlocked rings. The enzymes cluster in a group of β-carbonic anhydrase (β-CA) homologues that may comprise a subclass of CS(2) hydrolases within the β-CA family. Unlike CAs, the CS(2) hydrolases did not hydrate CO(2) but converted CS(2) and COS with H(2)O to H(2)S and CO(2). The CS(2) hydrolases of A. thiooxidans strains G8, 2Bp, Sts 4-3, and BBW1, like the CS(2) hydrolase of Acidianus strain A1-3, exist as both octamers and hexadecamers in solution. The CS(2) hydrolase of A. thiooxidans strain S1p forms only octamers. Structure models of the A. thiooxidans CS(2) hydrolases based on the structure of Acidianus strain A1-3 CS(2) hydrolase suggest that the A. thiooxidans strain G8 CS(2) hydrolase may also form a catenane. In the A. thiooxidans strain S1p enzyme, two insertions (positions 26 and 27 [PD] and positions 56 to 61 [TPAGGG]) and a nine-amino-acid-longer C-terminal tail may prevent catenane formation.

Oxidative stress and DNA damage in utero and embryo implantation of mice exposed to carbon disulfide at peri-implantation

Carbon disulfide (CS2) has reproductive toxicity but the mechanism remains unclear. The aim of the present study was to investigate the effect of oxidative stress and DNA damage on embryo implantation of mice exposed to CS2 at peri-implantation. CS2 exposure was on gestational day 3 (GD3), GD4, GD5 and GD6, separately, and the number of embryonic day 9 (E9) mouse embryos was obtained. DNA damage of endometrial cells, oxidative stress and 8-hydroxy-2′-deoxyguanosine (8-OH-dG) level in uterus tissues were tested with time series at different end points after exposure. The number of E9 mouse embryos significantly decreased in all CS2 exposure groups, especially on GD4 exposure. The rates of embryo implantation decreased by 43.05%, 63.74%, 60.45% and 47.26% for CS2 exposure on GD3, GD4, GD5 and GD6, respectively. Oxidative stress significantly increased within 24 h and reached the top level at 18 h after exposure. The same time-dependent trend was observed no matter when the exposure happened at peri-implantation. 8-OH-dG significantly increased at 18 h and 24 h after exposure by 893.8% and 647.4%, respectively, when compared with the control. The indexes of DNA damage significantly increased at 6 h after exposure, which appeared earlier than the changes of oxidative stress and 8-OH-dG. Besides, both oxidative stress and DNA damage showed a strong negative correlation with the number of E9 mouse embryos. The present study illustrated that CS2 directly induced DNA damage in endometrial cells and enhanced the action through oxidative stress, both of which were responsible for CS2-induced embryo loss.

Spectrophotometric Determination of Carbon Disulphide in the Workplace Air

This papre describes a simple method of carbon disulphide determination in the air of working environment in the chemical companies and plants after its absorption into aprotic N,N-dimethylformamide solvent. Carbon disulphide absorbed into aprotic solvent was transformed by using ammonium hydroxide on sulphides which were determined by spectrophotometry. 5,5′-Dithiobis(2-nitrobenzoic acid) and blue tetrazolium chloride were used as chromogenic sensing reagents. Colour-reducing products were measured at the wavelength of 500, respectively 520 nm. Detection limits for determination of carbon disulphide in the air are 0.2, respectively 0.4 mg·m−3.

Occupational exposures and mortality from cardiovascular disease among women textile workers in Shanghai, China

BACKGROUND

Exposure to textile fiber dusts, like particulate air pollution, may be associated with cardiovascular disease (CVD) mortality. Bacterial endotoxin, a potent inflammagen found in cotton dust, may be a specific risk factor.

METHODS

Female textile workers (N = 267,400) in Shanghai, China were followed for CVD mortality (1989-2000). Factory exposures were approximated by sector classifications based on materials and processes. Quantitative endotoxin and cotton dust measures were available for a subcohort (n = 3,188). Cox proportional hazards modeling was used to estimate hazard ratios (HR) and 95% confidence interval (CI).

RESULTS

Slightly elevated mortality risk for the cotton sector was seen for ischemic stroke (HR = 1.12, 95% CI: 0.97-1.31) and hemorrhagic stroke (HR = 1.12, 95% CI: 1.02-1.23). Similar hemorrhagic stroke mortality risk was observed in high dust sectors (HR = 1.12, 95% CI: 1.02-1.24). No association was observed for ischemic heart disease.

CONCLUSIONS

Exposures in textile factories may have contributed to CVD mortality among this cohort. The specific components of these exposures that may be harmful are not clear and should be further investigated.