Toxicological analysis of 17 autopsy cases of hydrogen sulfide poisoning resulting from the inhalation of intentionally generated hydrogen sulfide gas

A serial analysis of hydrogen sulfide poisoning: three group accidents

Hydrogen sulfide (H2S) is a powerful toxic gas in workplace incidents, and it poses a threat to colleagues or family members involved in rescues, leading to a "domino effect" of multiple deaths. In this report, we describe three incidents in which 10 people died, and we present the results of the analyses performed in different incidents, including paper pulp pit, sewer, and sewage well. We provide the macroscopic and morphological findings of ten victims, which include conjunctival hemorrhage, corneal erosion, pulmonary edema, and pulmonary hemorrhage. Additionally, we observed large amounts of waste paper pulp or black sludge in the upper and lower respiratory tracts or upper and lower gastrointestinal tracts of six victims. Furthermore, we conducted a toxicological examination of the victims' blood sulfide using an alkylation extraction approach combined with gas chromatography/mass spectrometry. The sulfide concentrations in the 10 victims ranged from 0.06 to 6.72 mg/L.

Retrospective analysis of forensic toxicology data from 2021 to identify patterns of various forensic cases

PURPOSE

Knowing and analyzing the characteristics and trends of forensic toxicology cases in a certain area is particularly important for a local government to establish an effective prevention and control system. The purpose of this work was to summarize data from forensic toxicology cases received by the Academy of Forensic Sciences (AFS) in 2021.

METHODS

As requested by the police or according to the details of cases, samples were systematically screened or analyzed by various methods. Liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry were used to identify medicinal drugs, drugs of abuse, pesticides, poison gases, etc. RESULTS: AFS received a total of 17,758 cases in 2021, of which 314 cases underwent autopsy. The main cause of death was sudden death, and the manner of death was mainly accident. Among 13,744 drug abuse cases, the number of positive cases was 1721, with a positive rate of 12.5%, and synthetic cannabinoids were the most frequently detected substances. In 3640 traffic cases, 85.3% of drivers were suspected of drunk driving. In 103 poisoning cases, hydrogen sulfide poisoning and pesticide suicide account for a large proportion. In drug-facilitated crimes, zolpidem was the most frequently tested component. In 55 case of dog poisonings, the main poisons were cyanides and succinylcholine, and the main poisoning tools were poisonous baits and poisonous syringe darts.

CONCLUSIONS

This study profiles the toxicological characteristics of forensic toxicological cases conducted at the AFS in 2021 and provides a scientific basis for poisoning cases and drug abuse prevention.

Hydrogen sulfide poisoning in forensic pathology and toxicology: mechanism and metabolites quantification analysis

Historically, hydrogen sulfide (H₂S) poisoning has extremely high and irreparable mortality. Currently, the identification of H₂S poisoning needs to combine with the case scene analysis in forensic medicine. The anatomy of the deceased seldom had obvious features. There are also a few reports about H₂S poisoning in detail. As a result, we give a comprehensive analysis of the related knowledge on the forensic aspect of H₂S poisoning. Furthermore, we provide the analytical methods of H₂S and its metabolite-which may assist in H₂S poisoning identification.

Liposomal methemoglobin as a potent antidote for hydrogen sulfide poisoning

Hydrogen sulfide (H₂S) induces acute and lethal toxicity at high concentrations. However, no specific antidotes for H₂S poisoning have been approved. Liposomal methemoglobin (metHb@Lipo) was developed as an antidote for cyanide poisoning. As the toxic mechanism of H₂S poisoning is the same as that of cyanide poisoning, metHb@Lipo could potentially be used as an antidote for H₂S poisoning. In this study, we evaluated the antidotal efficacy of metHb@Lipo against H₂S poisoning. Stopped-flow rapid-scan spectrophotometry clearly showed that metHb@Lipo scavenged H₂S rapidly. Additionally, metHb@Lipo showed cytoprotective effects against H₂S exposure in H9c2 cells by maintaining mitochondrial function. MetHb@Lipo treatment also improved the survival rate after H₂S exposure in vivo, with the maintenance of cytochrome c oxidase activity and suppression of metabolic acidosis. Moreover, metHb@Lipo therapy maintained significant antidotal efficacy even after 1-year-storage at 4-37 °C. In conclusion, metHb@Lipo is a candidate antidote for H₂S poisoning.

Decomposition kinetics and postmortem production of hydrogen sulfide and its metabolites

BACKGROUND

Hydrogen sulfide (H₂S), an endogenous gas, can also be generated from organics putrefaction. It is difficult for suspected cases of H₂S poisoning to determine whether H₂S in specimens is ingested by antemortem poisoning or generated from organics putrefaction. The aim of this study was to find the biomarkers of acute H₂S poisoning via comparing the concentrations of H₂S and its metabolites over time in specimens.

METHODS

The H₂S-spiked blood and blank blood group were established. The decomposition kinetics and the postmortem production of H₂S were studied due to organics putrefaction. The specimens were placed under 4 conditions of 37, 20, 4 and - 20 ℃. The content of H₂S in specimens was quantified by gas chromatography-mass spectrometry, and the contents of its metabolites (thiosulfate and trimethylsulfonium) were measured by liquid chromatography-mass spectrometry, and the variation of its concentration was evaluated.

RESULTS

In H₂S-spiked blood, H₂S decreased sharply in the initial stage at 37, 20 and 4 °C, and increased first and then decreased later; but it was relatively stable at - 20 °C. In spiked blood, thiosulfate was 9-fold higher than endogenous concentrations, which increased at first and then decreased during storage. Except for thiosulfate at 37 °C, H₂S and thiosulfate in blank blood both increased at first and then decreased in storage; but trimethylsulfonium (TMS) gradually decreased over time in both groups.

CONCLUSIONS

Thiosulfate is a reliable biomarker of acute H₂S poisoning at - 20℃ within 7 days. But H₂S, because of instability and volatility, is not an ideal poisoning marker. TMS is not an appropriate biomarker due to extremely low concentration in blood.

Forensic diagnostic approach of peri-volcanic area fatalities: About two cases at piton de la Fournaise

The Piton de la Fournaise, located on the island of Reunion, is a particularly active volcano that gathers many observers during its eruptions. However, this activity, if not supervised, can involve many risks. During the eruption of Piton de la Fournaise in April 2021, two geology students camped in the peri-eruptive zone. They were found dead 48 h later on the surface and were not in the immediate vicinity of a fumarole. The autopsy revealed superficial traumatic injuries, which did not explain the death. Internal examination of both victims showed a nonspecific asphyxia syndrome and hemorrhagic pulmonary edema, with no cause of death identified. Microscopic analysis confirmed the autopsy findings without providing new diagnostic elements. Toxicological analysis revealed abnormally high levels of sulfurous gases (H₂ S and SO₂ ) in the blood and lungs of both victims. The interpretation of all the forensic data allows us to conclude that the death was secondary to volcanic sulfur gas poisoning, despite the atypical context of this event. However, the meteorological conditions of the night of the event may have caused a stagnation of toxic volcanic gases on the ground, with concentrations high enough to cause fatal intoxication in these two persons, although they were not in a confined environment as is usually the case in cases of sulfur poisoning. The dramatic outcome of this event required a rigorous forensic diagnostic approach and reminds us of the need to respect safety conditions in peri-volcanic areas.

Fatal poisoning of four workers in a farm: Distribution of hydrogen sulfide and thiosulfate in 10 different biological matrices

We evaluate the distribution of sulfide and thiosulfate (TS) in biological samples of four dairy farmers died inside a pit connected to a manure lagoon. Autopsies were performed 4 days later. Toxicological analyses of sulfide and TS were made using an extractive alkylation technique combined with gas chromatography/mass spectrometry (GC/MS). Autopsies revealed: multiorgan congestion; pulmonary edema; manure inside distal airways of three of the four victims. Sulfide concentrations were cardiac blood: 0.5-3.0 μg/mL, femoral blood: 0.5-1.2 μg/mL, bile: <0.1-2.2 μg/mL; liver 2.8-8.3 μg/g, lung: 5.0-9.4 μg/g, brain: 2.7-13.9 μg/g, spleen: 3.3-6.3 μg/g, fat: <0.1-1.5 μg/g, muscle: 2.6-3.5 μg/g. TS concentrations were cardiac blood: 2.1-4.9 μg/mL, femoral blood: 2.1-2.3 μg/mL, bile: 2.5-4.4 μg/mL, urine: <0.5-1.8 μg/mL; liver <0.5-2.6, lung: 2.8-5.4 μg/g, brain: <0.5-1.9 μg/g, spleen: 1.2-2.9 μg/g, muscle: <0.5-5.6 μg/g. The cause of death was assessed to be acute poisoning by hydrogen sulfide (H₂S) for all the victims. Manure inhalation contributed to the death of three subjects. The measurement of sulfide and TS concentrations in biological samples contributed to better understand the sequence of the events. Subjects 3 provided the highest concentration of sulfide in brain, thus, supporting the hypothesis of a rapid loss of consciousness and respiratory depression. One by one, the other farmers entered the pit in attempts to rescue the coworkers but collapsed. Despite the rapid death, subject 3 was the only one with TS detectable in urine. This could be due to differences in metabolism of H₂S.

Sample preparation method with ultrafiltration for whole blood thiosulfate measurement

Quantitative analysis of thiosulfate is useful for diagnosing hydrogen sulfide poisoning. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables more rapid and sensitive measurements than previous methodologies. As simple measurements of blood thiosulfate concentration are affected by the blood matrix, blood is used as the solvent to prepare the standard solution for calibration curve generation. Thus, a large amount of blood devoid of thiosulfate is required. We developed a preparation method by incorporating an ultrafiltration step to overcome this limitation and generate a calibration curve using a standard solution prepared with pure water. We used this improved method to investigate the stability of thiosulfate in refrigerated samples. To compare the effects of refrigeration, blood samples were prepared using the following two methods: one sample was treated with a 50-kDa exclusion ultrafiltration membrane and the other was not treated. The samples were stored at 4 °C, and then measured at 0, 3, 6, 24, 48, and 96 h. The incorporation of the ultrafiltration step in the measurement procedure enabled the quantification of thiosulfate, by plotting a calibration curve using a standard of pure water; it did not require a blood standard. Additionally, the reduction in whole blood thiosulfate concentration was within 10% during 2 days of refrigeration. Thus, the need for a large amount of blood to prepare the standard solution was resolved by the ultrafiltration step in test sample preparation. This method is useful to measure thiosulfate concentration and is not hindered by sample refrigeration for a few days.

Acute myocardial injury following hydrogen sulfide poisoning

BACKGROUND

Hydrogen sulfide poisoning can cause severe myocardial injury, but the damage is subtle and can be easily misdiagnosed. This report presents the dynamic observation of myocardial injury associated with hydrogen sulfide poisoning.

CASE REPORT

Two young men presented with symptoms of "lightning-like" death immediately after entering a tank. They were found and rescued in 20 min at a time when they were already in a coma. Case 1 had no spontaneous breathing and pulse, while case 2 had spontaneous breathing and a pulse. Upon transfer to a local hospital, case 1 received continuous cardiopulmonary resuscitation which led to the recovery of his heart rate 3 min after arriving at the hospital. However, the patient remained in a Glasgow coma scale of 3. He was transferred to our hospital where he, unfortunately, died on the seventh day due to multiple organ failure. Case 2 was also transferred to the intensive care unit in our hospital and on the fourth day of hospitalization, the patient presented ST-segment elevation and dynamic changes in markers of myocardial injury. Changes in electrocardiogram and markers of myocardial injury were monitored and examination improved through conventional echocardiography, coronary artery CT, radionuclide myocardial perfusion imaging, and two-dimensional speckle tracking imaging strain. The treatment gradually improved the patient's myocardial injury and was discharged from the hospital.

CONCLUSION

Hydrogen sulfide poisoning can cause damage to myocardial function and the damage can be more insidious in nature and with a delayed onset. Recovery from myocardial damage can be very slow.

Emerging pharmacological tools to control hydrogen sulfide signaling in critical illness

Hydrogen sulfide (H2S) has long been known as a toxic environmental hazard. Discovery of physiological roles of H2S as a neurotransmitter by Kimura and colleagues triggered an intensive research in the biological roles of H2S in the past decades. Manipulation of H2S levels by inhibiting H2S synthesis or administration of H2S-releasing molecules revealed beneficial as well as harmful effects of H2S. As a result, it is now established that H2S levels are tightly controlled and too much or too little H2S levels cause harm. Nonetheless, translation of sulfide-based therapy to clinical practice has been stymied due to the very low therapeutic index of sulfide and the incomplete understanding of endogenous sulfide metabolism. One potential strategy to circumvent this problem is to use a safe and stable sulfide metabolite that may mediate effects of H2S. Alternatively, endogenous sulfide levels may be controlled using specific sulfide scavengers. In this review article, the role of endogenous H2S production and catabolism will be briefly reviewed followed by an introduction of thiosulfate and H2S scavengers as novel pharmacological tools to control H2S-dependent signaling.

Lethal Hydrogen Sulfide poisoning in open space: An atypical case of asphyxiation of two workers

Hydrogen sulfide is one of the most dangerous toxic gases that has led to the deaths in confined spaces of many workers. We report an atypical case of a fatal accident of H₂S poisoning in an open space when two workers died during the opening of a hatch on a tanker truck filled with leachate water. Despite being outdoors, the two workers, were suddenly and quickly overwhelmed by a lethal cloud of H₂S, which escaped like a geyser from the hatch and hovered over the top of the tanker making it impossible for them to survive. The first operator was engulfed by the sudden flow of lethal gas near the hatch while the second worker, who came to his aid, immediately lost consciousness and fell off the tanker onto the ground. Environmental toxicological analyses were carried out on the air near the hatch and inside the tanker 2h, 20 days and 70 days after the accident. Toxicological analyses on the blood were also carried out but unfortunately, no urine sample was available. The thiosulfate, detected by GC/MS analysis after derivatization of PFBBr, was found to be 0.01 and 0.04mM/L. These values are included in the medium-low lethal values of occupational fatalities involving H₂S reported in the literature.

Sulfur or Pollen? Chemical, Biological, and Toxicological Basis for the Correct Risk Communication of Urban Yellow Dust Deposition

Urban yellow dust deposition is a common phenomenon in many parts of the world, which is sometimes called "sulfur shower," "sulfur rain," or "pollen storm." Most people, especially those living in the vicinity of industrial facilities, wrongly perceive the yellow dust as sulfur when in fact it is pollen. The misunderstanding increases risk perception as people believe the "yellow powder" is a serious threat to their health. Based on simple observations, it is virtually impossible to differentiate sulfur from pollen, so risk communication should consider the chemical, biological, and toxicological aspects of these agents. In this review, we clarify that industrial emissions of sulfur are under the form of sulfides, oxides, and other volatile compounds which are gaseous and noncolored, and we explain that it is chemically impossible for gaseous sulfur to become solid yellow sulfur under normal environmental conditions. We also describe pollen and its release from trees, shrubs, and herbs a process influenced by atmospheric conditions. We suggest take-home messages that risk communicators may use when explaining the phenomenon to their communities.

Emissions of ammonia and hydrogen sulfide from typical dairy barns in central China and major factors influencing the emissions

There are few studies on the concentrations and emission characteristics of ammonia (NH₃) and hydrogen sulfide (H₂S) from Chinese dairy farms. The purpose of this study was to calculate the emission rates of NH₃ and H₂S during summer and to investigate influencing factors for NH₃ and H₂S emissions from typical dairy barns in central China. Eleven dairy barns with open walls and double-slope bell tower roofs from three dairy farms were studied. Five different locations in each barn were sampled both near the floor and at 1.5 m above the floor. Concentrations of NH₃ and H₂S were measured using the Nessler’s reagent spectrophotometry method and the methylene blue spectrophotometric method, respectively. NH₃ concentrations varied between 0.58 and 4.76 mg/m³ with the average of 1.54 mg/m³, while H₂S concentrations ranged from 0.024 to 0.151 mg/m³ with the average of 0.092 mg/m³. The concentrations of NH₃ and H₂S were higher during the day than at night, and were higher near the ground than at the height of 1.5 m, and were higher in the manure area than in other areas. NH₃ and H₂S concentrations in the barns were significantly correlated with nitrogen and sulfur contents in feed and manure (P < 0.05), and with temperature inside the barns (P < 0.05). Calculated emission rates of NH₃ ranged from 13.8 to 41.3 g NH₃/(AU·d), while calculated emission rates of H₂S ranged from 0.15 to 0.46 g H₂S/(AU·d). These results will serve as a starting point for a national inventory of NH₃ and H₂S for the Chinese dairy industry.

Toxicological investigations in a fatal and non-fatal accident due to hydrogen sulphide (H2S) poisoning

Hydrogen sulphide (H₂S) is one of the most toxic natural gas and represents a not rare cause of fatal events in workplaces. We report here a serious accidental poisoning by hydrogen sulphide inhalation involving six sailors. Three of them died while the other three survived and were transported to the emergency room. No greenish discolouration of the body, that could be a feature of these type of deaths, was observed at autopsy. Given that blood and/or urine H₂S detection does not allow to discriminate if it is related to inhalation or to putrefactive processes, the determination of thiosulphate, H₂S main metabolite, is decisive. The succession of fatal events reported here can be rebuilt by toxicological data interpretation: the subject 1 died after a longer interval of time as demonstrated by the highest blood and urine thiosulfate concentrations; the subject 2 died after a short interval of time as showed by a lower blood and urine thiosulfate concentrations than subject 1; the subject 3 died almost immediately after H₂S inhalation since he showed the lowest blood thiosulfate concentration, and no trace of sulphide and thiosulfate was found in the urine.

Proteomics and Toxicity Analysis of Spinal-Cord Primary Cultures upon Hydrogen Sulfide Treatment

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter recognized as an essential body product with a dual, biphasic action. It can function as an antioxidant and a cytoprotective, but also as a poison with a high probability of causing brain damage when present at noxious levels. In a previous study, we measured toxic liquoral levels of H₂S in sporadic amyotrophic lateral sclerosis (ALS) patients and in the familial ALS (fALS) mouse model, SOD1G93A. In addition, we experimentally demonstrated that H₂S is extremely and selectively toxic to motor neurons, and that it is released by glial cells and increases Ca²⁺ concentration in motor neurons due to a lack of ATP. The presented study further examines the effect of toxic concentrations of H₂S on embryonic mouse spinal-cord cultures. We performed a proteomic analysis that revealed a significant H₂S-mediated activation of pathways related to oxidative stress and cell death, particularly the Nrf-2-mediated oxidative stress response and peroxiredoxins. Furthermore, we report that Na₂S (a stable precursor of H₂S) toxicity is, at least in part, reverted by the Bax inhibitor V5 and by necrostatin, a potent necroptosis inhibitor.

Rapid Determination of H2S Poisoning in a Forensic Study Using a Novel Fluorescence Assay Based on Zn/Cu@BSA Nanoclusters

The quantitative determination of H2S in the blood can provide valid evidence for H2S poisoning through occupational exposure. However, known traditional methods for the detection of H2S in blood are time consuming, require complicated pretreatments, and have low sensitivity. In this paper, a new fluorescence sensing assay is proposed for the rapid detection of H2S poisoning in forensic cases based on bovine serum albumin (BSA)-stabilised zinc/copper (Zn/Cu) bi-metal nanoclusters (Zn/Cu@BSA NCs). The as-prepared Zn/Cu@BSA NCs probes have been characterised by UV-vis absorption and fluorescence spectroscopy. The fluorescence of Zn/Cu@BSA NCs can be quenched through specific interactions between HS−/S2− and the Zn2+/Cu2+ bi-metal ions. Under optimised conditions, the fluorescence sensing method was linear in the concentration range of 2.5 nM to 30 mM with 0.69 nM as the limit of detection. Moreover, the practical feasibility of this fluorescence sensing method has also been demonstrated by the analysis of mice blood samples containing different levels of sulfide and human blood samples from forensic cases of H2S poisoning. Compared with gas chromatography/mass spectrometry (GC/MS), this fluorescence sensing method is quite simple, straightforward, and can be accurate for the quantitative determination of H2S poisoning in a few minutes for forensic analysis. Overall, this is the first report of a bi-metal fluorescence sensing assay for detecting H2S poisoning directly in blood. This research may provide a new approach for forensic toxicologists to monitor poisoning by H2S using a fluorescence-sensing method.

Characterizing a mouse model for evaluation of countermeasures against hydrogen sulfide-induced neurotoxicity and neurological sequelae

Hydrogen sulfide (H₂ S) is a highly neurotoxic gas. It is the second most common cause of gas-induced deaths. Beyond mortality, surviving victims of acute exposure may suffer long-term neurological sequelae. There is a need to develop countermeasures against H₂ S poisoning. However, no translational animal model of H₂ S-induced neurological sequelae exists. Here, we describe a novel mouse model of H₂ S-induced neurotoxicity for translational research. In paradigm I, C57/BL6 mice were exposed to 765 ppm H₂ S for 40 min on day 1, followed by 15-min daily exposures for periods ranging from 1 to 6 days. In paradigm II, mice were exposed once to 1000 ppm H₂ S for 60 minutes. Mice were assessed for behavioral, neurochemical, biochemical, and histopathological changes. H₂ S intoxication caused seizures, dyspnea, respiratory depression, knockdowns, and death. H₂ S-exposed mice showed significant impairment in locomotor and coordinated motor movement activity compared with controls. Histopathology revealed neurodegenerative lesions in the collicular, thalamic, and cortical brain regions. H₂ S significantly increased dopamine and serotonin concentration in several brain regions and caused time-dependent decreases in GABA and glutamate concentrations. Furthermore, H₂ S significantly suppressed cytochrome c oxidase activity and caused significant loss in body weight. Overall, male mice were more sensitive than females. This novel translational mouse model of H₂ S-induced neurotoxicity is reliable, reproducible, and recapitulates acute H₂ S poisoning in humans.

Screening for volatile sulphur compounds in a fatal accident case

Acute fatal poisoning due to the inhalation of toxic gas frequently occurs in China. Volatile sulphur compounds (VSCs) are toxic to humans. In fatal poisoning investigations, such as those in industrial settings, a number of VSCs, including methanethiol (MT), dimethyl sulphide (DMS), dimethyl disulphide (DMDS) and dimethyl trisulphide (DMTS), can coexist. To date, there is limited data regarding these compounds in post-mortem cases. In the present study, we report toxicological findings in a fatal accident case with two victims. Headspace gas chromatography/flame ionization detector with two columns of different polarities was utilized to screen MT, DMS, DMDS and DMTS in blood. The limits of detection in both methods were 0.05 mg/mL. No sulphur compounds were detected in the blood samples of the two victims. DMS and DMDS were detected in the lungs at concentrations of 0.5 and 1.3 mg/g and 2.2 and 4.1 mg/g, respectively. DMDS liver concentrations were 2.5 and 6.5 mg/g. In addition to hydrogen sulphide, screening for additional VSCs could help establish the cause of death.

Liquid chromatography-tandem mass spectrometry method for the determination of thiosulfate in human blood and urine as an indicator of hydrogen sulfide poisoning

Being a stable metabolite of hydrogen sulfide, thiosulfate has been utilized as an index for hydrogen sulfide poisoning (HSP). Thiosulfate analysis is mainly performed using gas chromatography/mass spectrometry (GC-MS) due to its high sensitivity and specificity. The GC-MS analysis requires two-step derivatizations of thiosulfate, and the derivative is not stable in solution as it has a disulfide moiety. To resolve this stability issue, we developed a novel analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for monitoring the pentafluorobenzyl derivative of thiosulfate (the first reaction product of the GC-MS method) in this study. The established method exhibited high reproducibility despite being a more simplified and rapid procedure compare to the GC-MS method. Phenyl 4-hydroxybenzoate was used as an internal standard because 1,3,5-tribromobenzene which had been used in the GC-MS method was not suitable compound for LC-MS/MS with Electrospray ionization (ESI) negative detection. The linear regression of the peak area ratios versus concentrations was fitted over the concentration ranges of 0.5-250μM and 0.25-250μM in blood and urine, respectively. The validation results satisfied the acceptance criteria for intra- and inter-day accuracy and precision. Blood and urine samples from 12 suspected HSP cases were tested using this method. The thiosulfate concentration detected in the sample coincided well with that determined at the scene of each HSP accident.

Acute hydrogen sulfide-induced neuropathology and neurological sequelae: challenges for translational neuroprotective research

Hydrogen sulfide (H2 S), the gas with the odor of rotten eggs, was formally discovered in 1777, over 239 years ago. For many years, it was considered an environmental pollutant and a health concern only in occupational settings. Recently, however, it was discovered that H2 S is produced endogenously and plays critical physiological roles as a gasotransmitter. Although at low physiological concentrations it is physiologically beneficial, exposure to high concentrations of H2 S is known to cause brain damage, leading to neurodegeneration and long-term neurological sequelae or death. Neurological sequelae include motor, behavioral, and cognitive deficits, which are incapacitating. Currently, there are concerns about accidental or malicious acute mass civilian exposure to H2 S. There is a major unmet need for an ideal neuroprotective treatment, for use in the field, in the event of mass civilian exposure to high H2 S concentrations. This review focuses on the neuropathology of high acute H2 S exposure, knowledge gaps, and the challenges associated with development of effective neuroprotective therapy to counteract H2 S-induced neurodegeneration.

Development for the measurement of serum thiosulfate using LC-MS/MS in forensic diagnosis of H2S poisoning

Thiosulfate measurement is crucial to diagnosis of hydrogen sulfide (H2S) poisoning in forensic toxicology. Although GC-MS method is currently regarded as a standard thiosulfate measurement, it requires complicated sample preparation prior to analysis. This study presents a simple, rapid, and highly sensitive method for the quantitative analysis of serum thiosulfate by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method is based on selected reaction monitoring and has high sensitivity with a lower quantification limit of 0.5μM. Precision and accuracy of this method meet the basic requirements for quantitative analysis (intra- and inter-day tests have a relative standard deviation of ⩽10.4%; range of analytical recovery is 94.3-102.6%). On the measurements of serum thiosulfate by our developed method, a thiosulfate concentration as 57.5μM was detected clearly in the H2S poisoning case comparing to the non poisoning case in which only a trace amount of thiosulfate was observed.

Hydrogen Sulfide--Mechanisms of Toxicity and Development of an Antidote

Hydrogen sulfide is a highly toxic gas—second only to carbon monoxide as a cause of inhalational deaths. Its mechanism of toxicity is only partially known, and no specific therapy exists for sulfide poisoning. We show in several cell types, including human inducible pluripotent stem cell (hiPSC)-derived neurons, that sulfide inhibited complex IV of the mitochondrial respiratory chain and induced apoptosis. Sulfide increased hydroxyl radical production in isolated mouse heart mitochondria and F₂-isoprostanes in brains and hearts of mice. The vitamin B₁₂ analog cobinamide reversed the cellular toxicity of sulfide, and rescued Drosophila melanogaster and mice from lethal exposures of hydrogen sulfide gas. Cobinamide worked through two distinct mechanisms: direct reversal of complex IV inhibition and neutralization of sulfide-generated reactive oxygen species. We conclude that sulfide produces a high degree of oxidative stress in cells and tissues, and that cobinamide has promise as a first specific treatment for sulfide poisoning.

Effects of handling parameters on hydrogen sulfide emission from stored dairy manure

Hydrogen sulfide (H2S) emission from liquid manure in the process preceding field application is an important issue in fertigation systems. Given that H2S poses a significant health risk, it is important to determine the effects of different handling parameters on H2S emissions to prevent health risks to farmers. In this study, the effects of total solids (TS; 3, 5, 7, 9, and 11%) and mixing speed (100, 200, 300, and 400 rpm), duration (5, 15, 30, and 60 min), and frequency (one, two, three, and four times a day) on H2S emissions from two different dairy manures were investigated. The results indicate that the quantity of sulfur-containing substrate intake determines the potential of dairy manure to emit H2S because manure from cows fed with concentrate-based feed generates higher amounts of H2S than manure from cows fed with forage-based feed. The H2S concentration increased with TS concentration and reached a maximum of 1133 ppm at a TS of 9%; thereafter, it decreased with further increases in TS concentration. H2S emission increased with mixing speed with a peak concentration of 3996 ppm at 400 rpm. A similar trend was observed for mixing duration. However, there were no significant differences between the amounts H2S emitted at different frequencies of mixing (P > 0.05). The results indicate that mixing speed, duration, and TS are the major determinants of the quantity of H2S emitted from dairy manure. Therefore, to prevent health risks associated with H2S emission from dairy manure, it is recommended that the mixing speed and duration should be kept as low as possible, while a TS concentration of above 9% should be applied during the fertigation of dairy manure.

A gas chromatography-mass spectrometry based study on urine metabolomics in rats chronically poisoned with hydrogen sulfide

Gas chromatography-mass spectrometry (GS-MS) in combination with multivariate statistical analysis was applied to explore the metabolic variability in urine of chronically hydrogen sulfide- (H2S-) poisoned rats relative to control ones. The changes in endogenous metabolites were studied by partial least squares-discriminate analysis (PLS-DA) and independent-samples t-test. The metabolic patterns of H2S-poisoned group are separated from the control, suggesting that the metabolic profiles of H2S-poisoned rats were markedly different from the controls. Moreover, compared to the control group, the level of alanine, d-ribose, tetradecanoic acid, L-aspartic acid, pentanedioic acid, cholesterol, acetate, and oleic acid in rat urine of the poisoning group decreased, while the level of glycine, d-mannose, arabinofuranose, and propanoic acid increased. These metabolites are related to amino acid metabolism as well as energy and lipid metabolism in vivo. Studying metabolomics using GC-MS allows for a comprehensive overview of the metabolism of the living body. This technique can be employed to decipher the mechanism of chronic H2S poisoning, thus promoting the use of metabolomics in clinical toxicology.

A gas chromatography-mass spectrometry based study on serum metabolomics in rats chronically poisoned with hydrogen sulfide

Hydrogen sulfide poisoning is a common occupational hazard, whose mortality and incidence rates are first and second, respectively, among occupational poisoning incidents in China. The main target organs of its toxicity are in the central nervous system and respiratory system. However, there are currently no specific direct tests that can be used to diagnose poisoned patients. In this study, we developed a serum metabonomic method using orthogonal partial least squares-discriminate analysis (OPLS-DA), based on gas chromatography-mass spectrometry (GC/MS) to evaluate the effect of chronic poisoning by hydrogen sulfide in rats. The OPLS-DA data demonstrated that the model group (n = 60) differed significantly from the control group (n = 30), suggesting that the metabolic profiles of the two groups are markedly different. Alterations in the levels of some metabolites such as citrate, galactose, lactate, mannose, inositol, urea, phosphate, alanine and valine were detected by OPLS-DA analysis. We observed changes in metabolic pathways including lipid metabolism, energy metabolism and amino metabolism in the model group. Our results indicate that GC/MS-based metabonomic methods may provide novel detection means for chronic hydrogen sulfide poisoning.

Hydrogen sulfide intoxication

Hydrogen sulfide (H2S) is a hazard primarily in the oil and gas industry, agriculture, sewage and animal waste handling, construction (asphalt operations and disturbing marshy terrain), and other settings where organic material decomposes under reducing conditions, and in geothermal operations. It is an insoluble gas, heavier than air, with a very low odor threshold and high toxicity, driven by concentration more than duration of exposure. Toxicity presents in a unique, reliable, and characteristic toxidrome consisting, in ascending order of exposure, of mucosal irritation, especially of the eye ("gas eye"), olfactory paralysis (not to be confused with olfactory fatigue), sudden but reversible loss of consciousness ("knockdown"), pulmonary edema (with an unusually favorable prognosis), and death (probably with apnea contributing). The risk of chronic neurcognitive changes is controversial, with the best evidence at high exposure levels and after knockdowns, which are frequently accompanied by head injury or oxygen deprivation. Treatment cannot be initiated promptly in the prehospital phase, and currently rests primarily on supportive care, hyperbaric oxygen, and nitrite administration. The mechanism of action for sublethal neurotoxicity and knockdown is clearly not inhibition of cytochrome oxidase c, as generally assumed, although this may play a role in overwhelming exposures. High levels of endogenous sulfide are found in the brain, presumably relating to the function of hydrogen sulfide as a gaseous neurotransmitter and immunomodulator. Prevention requires control of exposure and rigorous training to stop doomed rescue attempts attempted without self-contained breathing apparatus, especially in confined spaces, and in sudden release in the oil and gas sector, which result in multiple avoidable deaths.

Hydrogen sulfide measurement by headspace-gas chromatography-mass spectrometry (HS-GC-MS): application to gaseous samples and gas dissolved in muscle

The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication.

A fatal work-related poisoning by hydrogen sulfide: report on a case

Hydrogen sulfide (H2S) is a colorless and potentially deadly gas that may cause rapid loss of consciousness and respiratory depression without warning. Although occupational exposure to H2S and the medical management of H2S-associated toxicity are widely established, it remains a problem in the sour gas industry and in other industrial settings, predominantly in new workers. In this article, the authors report a fatal case of a factory worker who died after breathing in H2S while undertaking a task that he was not trained to perform. Toxicological assessment supported by autopsy findings and circumstantial data was essential to clarify the cause of death, determined as H2S poisoning. This case emphasizes the need to develop work safety initiatives, improve on-the-job training, and introduce more consciousness to put on protective equipment for workers; indeed, correct training and education for workers regarding safety in the workplace may help to reduce worker fatalities.

The effects of acute hydrogen sulfide poisoning on cytochrome P450 isoforms activity in rats

Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe drugs, bupropion, metoprolol, midazolam, phenacetin, omeprazole, and tolbutamide, respectively. The experimental rats were randomly divided into two groups, control group and acute H2S poisoning group (inhaling 300 ppm for 2 h). The mixture of six probes was given to rats by oral administration and the blood samples were obtained at a series of time points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. The results for acute H2S poisoning and control groups were as follows: there was a statistically significant difference in the AUC and C max for bupropion, metoprolol, phenacetin, and tolbutamide, while there was no statistical pharmacokinetic difference for midazolam and omeprazole. Acute H2S poisoning could inhibit the activity of CYP2B6, CYP2D6, CYP1A2, and CYP2C9 in rats.

Suicidal carbon monoxide poisoning by combining formic acid and sulfuric acid within a confined space

Suicide by inhalation of carbon monoxide produced by mixing formic acid and sulfuric acid within a confined space is a rare method of suicide. This method is similar to the so-called "detergent suicide" method where an acid-based detergent is mixed with a sulfur source to produce hydrogen sulfide. Both methods produce a toxic gas that poses significant hazards for death investigators, first responders and bystanders. Carbon monoxide is an odorless gas, while hydrogen sulfide has a characteristic rotten eggs odor, so the risks associated with carbon monoxide are potentially greater due to lack of an important warning signal. While detergent suicides have become increasingly common in the USA, suicide with formic acid and sulfuric acid is rare with only three prior cases being reported. Greater awareness of this method among death investigators is warranted because of the special risks of accidental intoxication by toxic gas and the possibility that this method of suicide will become more common in the future.

A multicenter retrospective survey on a suicide trend using hydrogen sulfide in Japan

CONTEXT

In Japan, suicide by inhaling hydrogen sulfide (H2S) by mixing commercial products escalated into a nationwide trend in April 2008.

OBJECTIVE

We conducted a multicenter retrospective survey on the demographics, clinical features, treatments, and outcomes of patients exposed to H2S suicide attempts.

MATERIALS AND METHODS

Subjects included patients transported to emergency facilities in Japan from January 2005 to December 2011 following H2S suicide attempts. Among 277 facilities to which a letter requesting data collection was sent, questionnaires were sent to and filled out by the 47 (18%) facilities that agreed to provide data. Questionnaires were collected and data were extracted at Kitasato University.

RESULTS

A total of 156 patients were included in this survey. Patients involved in an H2S suicide attempt increased from 1 in 2007 to 51 in 2008, and gradually decreased from 44 in 2009 to 37 in 2010 and 23 in 2011. Ninety-two patients attempted H2S suicide (primary exposure group), and 64 were secondarily affected by the suicide attempt (secondary exposure group). Patients in the primary exposure group were young (mean, 30.3 years (10.9)), and male patients (n = 62) were approximately two times more likely to attempt H2S suicide than females (n = 30). Forty-eight patients in cardiopulmonary arrest at the scene did not survive. Five non-cardiopulmonary arrest patients died, and five patients who presented with a Glasgow coma scale (GCS) < 8 and lactic acidosis had neurological or cardiac signs or symptoms at discharge. Antidote therapy was performed on 26 of the primary group patients, but with poor outcomes. None of the secondary group patients were in cardiopulmonary arrest at the scene, five received antidotal therapy after arriving at the hospital, and all completely recovered from H2S exposure.

DISCUSSION AND CONCLUSION

Mortality (58%) among patients who attempted H2S suicide was very high, likely resulting from inhaling high concentrations of H2S after mixing commercial products in a sealed and confined space.

Suicide by carbon dioxide

Suicides by self-poisoning are common in all parts of the world. Among these intoxications, gases are rarely used, especially carbon dioxide (CO2). Very few cases of self-inflicted and deliberate carbon dioxide poisonings have been reported. This paper presents two uncommon suicides by carbon dioxide intoxication. In one case, a 53-year-old man tightly sealed a small bathroom and locked himself in it likely with dry ice. Warning notices were tagged to the door. In another case, a 48-year-old man working in a restaurant committed suicide by closing himself in a walk-in refrigerator and opening the stored carbon dioxide containers intended for the beverage dispensing equipment. The limited possibilities of proving lethal CO2 intoxications post-mortem necessitate a close cooperation of the involved parties during investigation. Only the synopsis of all findings permits a sound assessment regarding the manner and cause of death.

Sulfide induces apoptosis and Rho kinase-dependent cell blebbing in Jurkat cells

Hydrogen sulfide (H₂S) is a toxic gaseous substance, and accidental exposure to high concentrations of H₂S has been reported to be lethal to humans. Inhaled and absorbed H₂S is partially dissolved within the circulation and causes toxic effects on lymphocytes. However, the mechanisms involved in H₂S toxicity have not been well documented. In this study, we examined the cellular uptake and injury of sulfide-exposed human T lymphocytes (Jurkat). Cells were exposed to a H₂S donor, sodium hydroxysulfide (NaHS), at pH 6.0, 7.0, or 8.0 for 1 h at 37 °C in a sealed conical tube to avoid the loss of dissolved H₂S gas. Cytotoxicity and cellular sulfide concentrations increased dramatically as the pH of the NaHS solution decreased. Sulfide enhanced the cleavage of caspase-3 and poly (ADP-ribose) polymerase and induced early cellular apoptosis. A pan-caspase inhibitor reduced sulfide-induced apoptosis. These results indicate that sulfide induces pH-dependent and caspase-dependent apoptosis. We also found that blebbing of the plasma membrane occurred in sulfide-exposed cells. Both ROCK-1 and ROCK-2 (Rho kinases) were activated by sulfide, and sulfide-induced cell blebbing was suppressed by a ROCK inhibitor, suggesting that a Rho pathway is involved in sulfide-induced blebbing in lymphocytes.