Basin-scale reconstruction of euxinia and Late Devonian mass extinctions

The Devonian-Carboniferous transition marks a fundamental shift in the surface environment primarily related to changes in ocean-atmosphere oxidation states1,2, resulting from the continued proliferation of vascular land plants that stimulated the hydrological cycle and continental weathering3,4, glacioeustasy5,6, eutrophication and anoxic expansion in epicontinental seas3,4, and mass extinction events2,7,8. Here we present a comprehensive spatial and temporal compilation of geochemical data from 90 cores across the entire Bakken Shale (Williston Basin, North America). Our dataset allows for the detailed documentation of stepwise transgressions of toxic euxinic waters into the shallow oceans that drove a series of Late Devonian extinction events. Other Phanerozoic extinctions have also been related to the expansion of shallow-water euxinia, indicating that hydrogen sulfide toxicity was a key driver of Phanerozoic biodiversity.

Novel treatment of dihydrogen sulfide inhalation using hyperbaric oxygen during mass casualty

Hydrogen sulfide (H2S) is a toxic gas produced via breakdown of organic matter. Hydrogen sulfide exposure can cause symptoms ranging in severity from mild effects (dizziness, headache, nausea) to severe lactic acidosis, respiratory failure, pulmonary edema, cardiac arrhythmias and death. Treatment modalities include oral countermeasures and 100% FiO2 with supportive therapy. However, case studies utilizing hyperbaric oxygen (HBO2) therapy have been reported with general benefit seen in severe cases of toxicity. In this report, cases of mild to moderate H2S toxicity occurred aboard a U.S. Navy ship, resulting in a mass casualty incident of more than 30 patients. Patient symptoms included dizziness, headaches, nausea, vomiting, and one patient with altered mental status. Most patients' symptoms resolved after several hours of supportive therapy, but six patients had symptoms refractory to 100% FiO2 at 1 atm. These six patients received HBO2 therapy with a USN Treatment Table 9 after consultation with the local emergency room and hyperbaric assets. Four separate chambers were utilized, including two chambers onboard USN ships and the local explosive ordnance disposal (EOD) chamber. Complete resolution of symptoms in all six patients was achieved within the first breathing period. Patients were monitored after treatment aboard the USN ship medical department. No patients required emergency department care. These cases demonstrate an expanded use of HBO2 to include moderate cases of H2S toxicity refractory to first-line therapy.

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.

Methylene Blue Administration During and After Life-Threatening Intoxication by Hydrogen Sulfide: Efficacy Studies in Adult Sheep and Mechanisms of Action

Exposure to toxic levels of hydrogen sulfide (H2S) produces an acute cardiac depression that can be rapidly fatal. We sought to characterize the time course of the cardiac effects produced by the toxicity of H2S in sheep, a human sized mammal, and to describe the in vivo and in vitro antidotal properties of methylene blue (MB), which has shown efficacy in sulfide intoxicated rats. Infusing NaHS (720 mg) in anesthetized adult sheep produced a rapid dilation of the left ventricular with a decrease in contractility, which was lethal within about 10 min by pulseless electrical activity. MB (7 mg/kg), administered during sulfide exposure, maintained cardiac contractility and allowed all of the treated animals to recover. At a dose of 350 mg NaHS, we were able to produce an intoxication, which led to a persistent decrease in ventricular function for at least 1 h in nontreated animals. Administration of MB, 3 or 30 min after the end of exposure, whereas all free H2S had already vanished, restored cardiac contractility and the pyruvate/lactate (P/L) ratio. We found that MB exerts its antidotal effects through at least 4 different mechanisms: (1) a direct oxidation of free sulfide; (2) an increase in the pool of "trapped" H2S in red cells; (3) a restoration of the mitochondrial substrate-level phosphorylation; and (4) a rescue of the mitochondrial electron chain. In conclusion, H2S intoxication produces acute and long persisting alteration in cardiac function in large mammals even after all free H2S has vanished. MB exerts its antidotal effects against life-threatening sulfide intoxication via multifarious properties, some of them unrelated to any direct interaction with free H2S.

Hydrogen sulfide gas poisoning in fish garbage room: A report of a fisherman

We report the case of a fisherman who was exposed to high concentrations of hydrogen sulfide (H2S) gas from the fish garbage room. The patient survived and was discharged with full recovery from the hospital. H2S is a colourless, foul smelling and highly toxic gas next to carbon monoxide, which causes inhalation death. It is a by-product of various industrial processes particularly involves exposure from agriculture, petrochemical industry and organic matter decomposition from sewage processing. It is a by-product of H2S has been referred as the "knock down gas" because inhalation of high concentrations can cause immediate loss of consciousness and death. Although early use of amyl nitrate and hyperbaric oxygen shows some benefit in literature, supportive care remains the mainstay of treatment. Emergency physicians and pre-hospital care personnel are not very familiar with such exposure due to its rarity. This becomes more relevant in the developing world settings where there are rising concerns about the unsafe exposure to hazardous chemicals and its impact on human health. Emergency physicians working in Pakistan should be aware of this entity especially in regard to fishermen presenting to the Emergency Department with such a clinical presentation and its toxic manifestations. This incident also illustrates the need of enforcement of health and safety regulations in the fishing industry.

Outcome after hydrogen sulphide intoxication

AIM

Hydrogen sulphide (H2S) intoxication in man is frequently associated with a fatal outcome. In small animal models hydrogen sulphide has demonstrated profound protection against hypoxia. No reports that focus on a potential protective effect in humans have been published.

METHODS

The frequency and outcome of a large cohort of hydrogen sulphide intoxications is described.

RESULTS

From 1980 until 2013, 35 accidents totalling 56 victims occurred of whom at least 24 (43%) survived. Of the 8 patients with documented cardiopulmonary resuscitation on the scene, 6 (75%) survived. In some of these cases with good outcome the exposure time to very high hydrogen sulphide levels before extraction and resuscitation was more than 45min.

CONCLUSION

Manure related hydrogen sulphide intoxication is associated with a high mortality, although in some cases, recovery appears to be far more favourable than the initial presentation would suggest. Possibly protection from hypoxic injury due to induction of a suspended animation-like state by hydrogen sulphide may be responsible.

Immediate and Long-Term Outcome of Acute H2S Intoxication Induced Coma in Unanesthetized Rats: Effects of Methylene Blue

BACKGROUND

Acute hydrogen sulfide (H2S) poisoning produces a coma, the outcome of which ranges from full recovery to severe neurological deficits. The aim of our study was to 1--describe the immediate and long-term neurological effects following H2S-induced coma in un-anesthetized rats, and 2--determine the potential benefit of methylene blue (MB), a compound we previously found to counteract acute sulfide cardiac toxicity.

METHODS

NaHS was administered IP in un-sedated rats to produce a coma (n = 34). One minute into coma, the rats received MB (4 mg/kg i.v.) or saline. The surviving rats were followed clinically and assigned to Morris water maze (MWM) and open field testing then sacrificed at day 7.

RESULTS

Sixty percent of the non-treated comatose rats died by pulseless electrical activity. Nine percent recovered with neurological deficits requiring euthanasia, their brain examination revealed major neuronal necrosis of the superficial and middle layers of the cerebral cortex and the posterior thalamus, with variable necrosis of the caudate putamen, but no lesions of the hippocampus or the cerebellum, in contrast to the typical distribution of post-ischemic lesions. The remaining animals displayed, on average, a significantly less effective search strategy than the control rats (n = 21) during MWM testing. Meanwhile, 75% of rats that received MB survived and could perform the MWM test (P<0.05 vs non-treated animals). The treated animals displayed a significantly higher occurrence of spatial search than the non-treated animals. However, a similar proportion of cortical necrosis was observed in both groups, with a milder clinical presentation following MB.

CONCLUSION

In conclusion, in rats surviving H2S induced coma, spatial search patterns were used less frequently than in control animals. A small percentage of rats presented necrotic neuronal lesions, which distribution differed from post-ischemic lesions. MB dramatically improved the immediate survival and spatial search strategy in the surviving rats.

Suicide by gases in England and Wales 2001-2011: evidence of the emergence of new methods of suicide

BACKGROUND

Increases in suicide deaths by gassing, particularly carbon monoxide poisoning from burning barbecue charcoal, have occurred in many parts of East Asia and resulted in rises in overall suicide rates in some countries. Recent trends in gas poisoning suicides outside Asia have received little attention.

METHODS

We analysed suicides by gassing in England and Wales (2001-2011) using national suicide mortality data enhanced by free text searching of information sent by coroners to the Office for National Statistics (ONS). We conducted specific searches for suicides involving barbecue charcoal gas, helium, and hydrogen sulphide. We analysed coroners' records of eight people who used helium as a method of suicide, identified from systematic searches of the records of four coroners.

RESULTS

Gassing accounted for 5.2% of suicide deaths in England and Wales during 2001-2011. The number of gas suicides declined from 368 in 2001 to 174 by 2011 (a 53% reduction). The fall was due to a decline in deaths involving car exhaust and other sources of carbon monoxide. There was a rapid rise in deaths due to helium inhalation over the period, from five deaths in the two year period 2001-2002 to 89 in 2010-2011 (a 17-fold increase). There were small rises in deaths involving hydrogen sulphide (0 cases in 2001-2002 versus 14 cases in 2010-2011) and barbecue charcoal gas (1 case in 2001-2002 versus 11 cases in 2010-2011). Compared to individuals using other methods, those suicides adopting new types of gas for suicide were generally younger and from more affluent socioeconomic groups. The corones' records of four of the eight individuals dying by helium inhalation whose records were reviewed showed evidence of Internet involvement in their choice of method.

LIMITATIONS

We were not able to identify the source of carbon monoxide (car exhaust or barbecue charcoal) for over 50% of cases.

CONCLUSION

Increases in helium inhalation as a method of suicide have partially offset recent decreases in suicide by the use of car exhaust. Public health measures are urgently needed to prevent a potential epidemic rise in the use of helium similar to the recent rises in charcoal burning suicides in East Asia.

[Sewer gas induced myocardial toxicity]

We report the case of a 19 year-old worker who collapsed after acute exposure to sewer gas. He rapidly developed cardiorespiratory failure with electrocardiographic, echocardiographic and laboratory findings of myocardial involvement. The mainstay of the therapy was mainly supportive treatment with a successful outcome.

An approach for estimating toxic releases of H2S-containing natural gas

China is well known being rich in sulfurous natural gas with huge deposits widely distributed all over the country. Due to the toxic nature, the release of hydrogen sulfide-containing natural gas from the pipelines intends to impose serious threats to the human, society and environment around the release sources. CFD algorithm is adopted to simulate the dispersion process of gas, and the results prove that Gaussian plume model is suitable for determining the affected region of the well blowout of sulfide hydrogen-containing natural gas. In accordance with the analysis of release scenarios, the present study proposes a new approach for estimating the risk of hydrogen sulfide poisoning hazards, as caused by sulfide-hydrogen-containing natural gas releases. Historical accident-statistical data from the EGIG (European Gas Pipeline Incident Data Group) and the Britain Gas Transco are integrated into the approach. Also, the dose-load effect is introduced to exploit the hazards' effects by two essential parameters - toxic concentration and exposure time. The approach was applied to three release scenarios occurring on the East-Sichuan Gas Transportation Project, and the individual risk and societal risk are classified and discussed. Results show that societal risk varies significantly with different factors, including population density, distance from pipeline, operating conditions and so on. Concerning the dispersion process of hazardous gas, available safe egress time was studied from the perspective of individual fatality risks. The present approach can provide reliable support for the safety management and maintenance of natural gas pipelines as well as evacuations that may occur after release incidents.

Delayed myocardial injury following acute hydrogen sulfide intoxication

INTRODUCTION

Hydrogen sulfide is a toxic, colorless gas produced by decaying organic matter. Its toxic effects are due to blocking of cellular respiratory enzymes, leading to anoxia.

CASE PRESENTATION

We report a 28-year-old man who attempted suicide using hydrogen sulfide gas. When the emergency service arrived, his friend was dead and the patient was unconscious. He received supportive treatment and survived. In this patient both skeletal muscle and myocardial injury was observed after hydrogen sulfide intoxication. Skeletal muscle damage occurred first, because enzymes peak consisted of creatine phosphokinase, aspartate aminotransferase, and myoglobin was observed on hospital day 4. Myocardial injury was apparent on hospital day 15, because the subsequent enzymes peak was comprised of cardiac enzymes and associated electrocardiographic abnormalities. On hospital day 3, myocardial injury was detected and it evolved over the next 3 weeks to recover completely.

CONCLUSION

The mechanisms of rhabdomyolysis and myocardial injury resulting from hydrogen sulfide poisoning are not known, but may be related to cellular anoxia or a direct toxic effect. This case highlights not only the risk of delayed cardiac damage, but also rhabdomyolysis, and emphasizes that careful monitoring of cardiac function and of the levels of skeletal muscle-related enzymes is essential for victims of hydrogen sulfide poisoning.

[The pulmonary CT manifestations of acute moderate or severe hydrogen sulphide poisoning fishermen]

OBJECTIVE

To discuss the clinical manifestations and CT features of acute moderate or severe hydrogen sulphide poisoning fishermen.

METHODS

The clinic and CT datas of 8 acute moderate or severe hydrogen sulphide poisoning cases were retrospectively analysed.

RESULTS

The lesions located at two pulmonary each leaf in 3 cases, located at both lower lungs in 3 cases and asymmetry leaves in 2 cases. Lesions form: little patchy shadow in 8 cases (8/8), fibrous band shadow in 4 cases (4/8), ground glass shadow in 3 cases (3/8), peripheral fuzzy interlobular nodule in 4 cases (4/8); 5 cases complicated with pleural effusion; After treatment 6 ∼ 10 days, the pulmonary shadows were absorbed obviously; Fibrous band shadow was residual in a case after a follow-up of 2 months.

CONCLUSION

With definite history of hydrogen sulphide inhalation and the corresponding clinical manifestations, and if fishermen contacted for a long time, who would be made chemical pulmonary damage; Combined with the imaging manifestations, the diagnosis as well as the severity of pulmonary damage could be made.

[Study on the standard of health protection zone for petroleum processing industry]

OBJECTIVE

To establish health protection zone standards for petroleum processing industry.

METHODS

The intensity of characteristic pollutants from fugitive emission were estimated by the inverse method of ground concentration through field survey and monitoring for representative petroleum processing industry, which was calculated health protection zone by using the model of atmospheric diffusion.

RESULTS

Characteristic pollutant of fugitive emission source from petroleum processing industry was confirmed as hydrogen sulfide. When local average wind speed in the past five years was less than 2, 2-4 m/s and more than 4 m/s respectively and meanwhile the scale of petroleum processing industry was less than 8 million tons, the recommended value of health protection zone were 900, 800, 700 m respectively. Besides, when the scale of petroleum processing industry was more than 8 million tons and in the same wind speed level, the recommended value of health protection zone were 1200, 1000, 900 m respectively.

CONCLUSIONS

Recommended value of health protection zone for petroleum processing industry was reasonable and feasible through revising and improving of the version of 1987's standard.

[Effect of ulinastatin on oxidative stress and nuclear factor E2-related factor 2 expression in the lung tissues of acute hydrogen sulfide intoxicated rats]

OBJECTIVE

To investigate the dynamic changes of oxidative stress and nuclear factor-E2 related factor 2 (Nrf2) expression in the lung tissues of acute hydrogen sulfide (H2S) intoxicated rats and intervention effects of ulinastatin (UTI).

METHODS

A total of 96 SD rats of clean grade were divided randomly into four groups: normal control group (n = 8), UTI control group (n = 8), H2S -intoxicated model group (n = 40), and UTI treatment group (n = 40). The H2S-intoxicated model group and UTI treatment group were exposed to H2S (283.515 mg/m3) by inhalation for 1h, then UTI treatment group was intraperitoneally exposed to UTI at the dose of 10(5) U/kg for 2 h. H2S-intoxicated model group and UTI treatment group were sacrificed at 2, 6, 12, 24 and 48 h after exposure, respectively. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione (GSH) in the rat lung tissues were measured. The expression levels of Nrf2 mRNA in the rat lung tissues were detected. Pathological changes of rat lung tissues were observed under a light microscope and the lung injury scores were evaluated.

RESULTS

Compared with control group, the pulmonary SOD, CAT and GSH levels at 2,6 and 12 h after exposure and the pulmonary GSH-Px levels at 2, 6, 12 and 24 h after exposure in H2S-intoxicated model group significantly decreased (P < 0.05 or P < 0.01). The levels of pulmonary MDA at 2, 6, 12 and 24 h after exposure in H2S-intoxicated model group were significantly higher than those in normal control group (P < 0.01). As compared with H2S -intoxicated model group, the pulmonary GSH-Px activities at 6 and 12 h after exposure, the pulmonary CAT activities at 2, 6 and 12 h after exposure, the pulmonary GSH levels at 2, 6, 12 and 24 h after exposure and the pulmonary SOD activities at 2, 6, 12, 24 and 48 h after exposure in UTI treatment group significantly increased (P < 0.05 or P < 0.01), the pulmonary MDA levels at 2, 6 and 12 h after exposure in UTI treatment group significantly decreased (P < 0.01). The expression levels of Nrf2 mRNA at 2, 6, 12, 24 h after exposure in H2S-intoxicated model group were 0.314 +/- 0.011, 0.269 +/- 0.010, 0.246 +/- 0.011 and 0.221 +/- 0.018, respectively, which were significantly higher than those (0.149 +/- 0.012) in control group (P < 0.01). As compared with H2S-intoxicated model group, the expression levels (0.383 +/- 0.017, 0.377 +/- 0.014, 0.425 +/- 0.017, 0.407 +/- 0.011 and 0.381 +/- 0.010) of Nrf2 mRNA at 2, 6, 12, 24 and 48 h after exposure in UTI treatment group significantly increased (P < 0.01). The lung injury at 24 h after exposure in H2S-intoxicated model group was higher than that in UTI treatment group. Histopathological examination showed that the scores of lung injury at 12, 24 and 48 h after exposure in UTI treatment group was significantly lower than those in H2S-intoxicated model group (P < 0.01).

CONCLUSION

Oxidative stress and Nrf2 activation may be the important factors in rat lung injury induced by H2S-intoxicated, UTI may reduce the rat lung injury and protect the rat lung from damage induced by H2S by inhibiting ROS, improving the imbalance in redox and up-regulating Nrf2 mRNA expression.

[Lethal myocardial injury associated with hydrogen sulfide poisoning: report of two cases]

We investigated two cases of hydrogen sulfide poisoning in which the patients showed lethal myocardial injury. Both patients had planned to commit suicide by inhaling hydrogen sulfide. In case 1, a 17-year-old man was confused and was brought to our hospital by ambulance. An electrocardiogram (ECG) revealed diffuse elevation of the ST segment on the second hospital day. The patient recovered and was discharged from the hospital on the 15th day. However, he died suddenly on the 18th day. In case 2, a 21-year-old man was found lying on the floor and was admitted to our hospital. ECG showed tall T waves after 5 hr. Tachycardia and tachypnea occurred after 12 hr. After 16 hr, the ECG showed a marked elevation of the ST segment, and the patient developed cardiac arrest. Even though percutaneous cardiopulmonary support was used, he died on the 4th day. It is highly probable that myocardial injury asscociated with hydrogen sulfide poisoning was not caused by systemic hypoxia but by selective myocardial toxicity. These cases demonstrate that delayed presentation of a lethal myocardial injury should be considered while treating cases of hydrogen sulfide poisoning.

[Fatal hydrogen sulphide (H2S) poisoning in "confined spaces"]

This paper deals with the problem of fatal accidents that occur repeatedly in "confined spaces", with particular attention to exposure to hydrogen sulfide (H2S). This, at high concentrations, appears to be the most compatible with the dynamics of many recent incidents with sudden death. H2S offers little chance to escape at high concentrations because of the smell that causes paralysis of olfactory nerves and sudden loss of consciousness. Besides the problem of acute exposure to high concentrations, health effects may also be caused by prolonged and repeated exposures to lower doses: at low concentrations can occur eyes irritation with keratoconjunctivitis and, at higher concentrations, the risk of pulmonary oedema or chronic central nervous system sequelae. In this paper several aspects are detailed, including an interpretative analysis of the content of Articles 66 and 121 of Legislative Decree 81/2008 and subsequent amendments, the work contexts where H2S is present as a raw material or product of the process and the effects on human health. Moreover, due to few epidemiological initiatives at national level, some aspects related to the accident dynamics are taken into account through the reconstruction of cases of fatal accidents occurred in Italy in recent years and comparing it with that reported in the literature of other Countries.

[Effect of oxygen therapy on the morphology of cardiac muscle, lung and liver in rats with acute hydrogen sulfide intoxication]

OBJECTIVE

To evaluate the effects of different oxygen therapy technique (different concentrations of normobaric oxygen and the hyperbaric oxygen) on the ultrastructure of cardiac muscle, lung and liver in rats with acute hydrogen sulfide intoxication.

METHODS

One hundred healthy male Wistar rats were randomly divided into five groups: normal control group (A), poisoned group (B), oxygen therapy group (C), oxygen therapy group (D) and oxygen therapy group (E). After the exposure to 300 ppm H2S for 60 min in a static exposure tank (1 m3), the rats were treated with oxygen therapy, C, D and E groups were given 33% oxygen, 50% oxygen of atmospheric oxygen and hyperbaric oxygen therapy for 100 min, respectively. The rats in normal control group inhaled air under the same environment. After exposure and therapy, the tissues of lung, heart and liver were observed under light microscope and electron microscope.

RESULTS

The results of light microscope examination showed that the broken and not well aligned cardiac myofilaments, cytoplasmic edema and pyknosis could be seen in group B. The well aligned and clear cardiac myofilaments appeared in group C, D and E. The alveolar hemorrhage, edema and inflammatory cells exudation could not be seen in group A. Alveolar epithelial cell edema, unsmooth alveolar edge and alveolar inflammatory cells exudation could be found in group B. The unsmooth alveolar septal borders and pulmonary edema could be seen occasionally in group C and D, the alveolar inflammatory cells exudation could not be seen in group E. The regular hepatic boards and the uniform hepatic cellular nuclei were found in group A. The disordered hepatic boards, widened cellular gaps and cytoplasmic edema could be seen occasionally in group B. The irregular hepatic boards and ballooning degeneration could be seen in group C and D. The regular hepatic boards and uniform cytoplasm could be found in group E. The results of electron microscope examination indicated that the mitochondrial swelling, autolyzing, fuzzy and breakage of myocardial cells were observed in group B; the clear mitochondrial structure appeared in group E. The apoptosis and organelle vacuole of alveolar epithelial cells could be observed in group B. The relatively normal nuclei of alveolar epithelial cells could be seen in group E. The lax cytoplast structure of hepatocytes, unclear nuclear membrane, lumped chromatin, slightly swelled mitochondria and phagosomes were observed in group B. However, no improved change was observed in group C, D and E.

CONCLUSION

Hydrogen sulfide could induce the extensive and severe damage of myocardial mitochondria, alveolar epithelial cells and hepatocytes, the oxygen therapy in good time could reduce significantly the myocardial injury, and improve the lung injury to some extent. High-pressure oxygen therapy is better than the normobaric oxygen therapy.

Diagnostics of fatal hydrogen sulfide poisonings

INTRODUCTION

Cases of fatal hydrogen sulfide poisonings are rarely presented in forensic medicine practice. They mostly occur in occupational settings and occasionally are mass. Due to occupational poisonings caused by gases, hydrogen sulfide is ranked second regarding frequency-dependent incidence. Hydrogen sulfide at high concentrations is undetectable to human senses resulting in increased risk of fatal poisoning. Such poisonings represent a particular group with respect to their objectification by toxicological analysis.

AIM

The aim of this paper is to demonstrate possibilities of laboratory diagnostics of fatal hydrogen sulfide poisonings.

PATIENTS AND METHODS

The paper provides a retrospective overview of 15 cases of fatal hydrogen sulfide poisonings which occurred in the history of the Institute of Forensic Medicine of the School of Medicine, Comenius University in Bratislava. All cases were completely analysed by morphological and toxicological methods. The samples of blood and pulmonary tissue were examined in the toxicological analysis. The method of analysis of alveolar air was developed by Bauer. An experiment for detection of post-mortem production of hydrogen sulfide in the body was performed.

RESULTS

Morphological findings in all autopsied and analysed cases were similar and nonspecific for poisoning diagnosis. A significant change in possibilities of toxicological analysis occurred in 1968. Since then a direct identification of toxic gas through the analysis of alveolar air has been possible.

CONCLUSION

Taking into consideration summarization and comparison of the analysis results of the cases from archive materials of the authors, it is possible to claim that at the workplace in Bratislava a unique objective method of proving this gaseous poison in biological material used so far has been developed. Some negative or unconvincing results of toxicological analysis again refer to pitfalls of diagnostics of hydrogen sulfide poisonings, which must be complex and based upon an efficient collaboration particularly between a medical examiner and toxicologist-analyst together with other bodies complementing the required spectrum of investigated circumstances and clinical data.

Improvement in a patient suffering from cardiac injury due to severe hydrogen sulfide poisoning: a long-term examination of the process of recovery of heart failure by performing nuclear medicine study

In 2008, 1,007 cases of suicide in which hydrogen sulfide was used as a suicidal agent were reported in Japan, and this has become a serious social problem. Here, we report the successful revival of a patient suffering from a severe disturbance of consciousness and respiratory failure caused by hydrogen sulfide poisoning; further, his condition was complicated by myocardial infarction. This is an important case where we examined the tendency toward improvement in myocardial damage in a patient in the acute phase of severe hydrogen sulfide poisoning who was treated for approximately 6 months.

[Accidental poisoning and test for it]

There are many dangerous materials which cause poisoning, toxins or poisons, in our lives. We may suddenly suffer from the effects of these materials by inhalation or ingestion before we are aware of the risk. It is very important to identify toxins or poisons to prevent poisoning and treat the poisoned patients. We have to learn from previous accidents the way to resolve future problems.

Acute hydrogen sulfide poisoning in a dairy farmer

INTRODUCTION. Hydrogen sulfide is a lipid-soluble gas produced in occupational settings and from decaying organic matter. We present a 36-year-old man who developed acute respiratory arrest from hydrogen sulfide poisoning while performing work as a dairy farmer.

CASE REPORT

The subject entered a poorly ventilated tank containing degrading eggs and, within seconds, collapsed. Coworkers were able to extract him within minutes but he was apneic. He was intubated by emergency medical services and subsequently managed with supportive care in the intensive care unit. Upon admission, a powerful rotten egg scent was noted and a hydrogen sulfide poisoning was suspected. Serum analysis for the presence of thiosulfate confirmed the diagnosis. Nitrite therapy was not administered as the subject arrived outside of the therapeutic window of effectiveness and showed evidence of excellent oxygenation. His examinations following arrival were consistent with an anoxic brain injury which slowly improved several months after the incident with intensive neuro-rehabilitation.

DISCUSSION

Hydrogen sulfide is a mitochondrial toxin and inhibits cytochrome-aa(3) and prevents cellular aerobic metabolism. Therapies for toxic exposures include removal from the contaminated environment, ventilation with 100% oxygen, and nitrite therapy if administered immediately after exposure. Hyperbaric oxygen (HBO) therapy has anecdotal support and remains controversial.

CONCLUSION

Hydrogen sulfide is a significant occupational health hazard. Education, personal protective equipment, and early treatment are important in improving outcomes.

Proceedings of the Hydrogen Sulfide Health Research and Risk Assessment Symposium October 31-November 2, 2000

The Hydrogen Sulfide Health Research and Risk Assessment Symposium came about for several reasons: (1) increased interest by the U.S. Environmental Protection Agency (EPA) and several state agencies in regulating hydrogen sulfide (H2S); (2) uncertainty about ambient exposure to H2S; (3) confusion and disagreement in the literature about possible health effects at low-level exposures; and (4) presentation of results of a series of recent animal bioassays. The American Petroleum Institute (API) proposed this symposium and the EPA became an early co-sponsor, with the Chemical Industry Institute of Toxicology (CIIT) and the American Forest & Paper Association (AF&PA) contributing expertise and funding assistance. The topics covered in this symposium included Animal Research, Human Research, Mode-of-Action and Dosimetry Issues, Environmental Exposure and Monitoring, Assessment and Regulatory Issues, and closed with a panel discussion. The overall goals of the symposium were to: gather together experts in H2S health effects research and individuals from governmental agencies charged with protecting the public health, provide a venue for reporting of recent research findings, identify gaps in the current information, and outline new research directions and promote research collaboration. During the course of the symposium, presenters provided comprehensive reviews of the state of knowledge for each topic. Several new research proposals discussed at the symposium have subsequently been initiated. This report provides a summary of the talks, poster presentations, and panel discussions that occurred at the Hydrogen Sulfide Health and Risk Assessment Symposium.