The usefulness of thiosulfate as an indicator of hydrogen sulfide poisoning: three cases

We examined the usefulness of thiosulfate as an indicator of hydrogen sulfide poisoning by analysing sulfide and thiosulfate in three cases. In the first (non-fatal) case sulfide and thiosulfate were not detected in the blood samples from any of the four workers involved in the accident. In the urine samples, only thiosulfate was detected in three out of the four workers at a concentration of 0.12-0.43 micromol/ml, which was 4-14 times higher than the level in a healthy person. In the second (fatal) case sulfide and thiosulfate were detected in the blood sample at concentrations of 0.007 micromol/ml for sulfide, and 0.025 micromol/ml for thiosulfate. The thiosulfate concentration was at least 8 times higher than the level in a healthy person. In the third (fatal) case sulfide and thiosulfate were detected in the blood sample at concentrations of 0.95 micromol/ml for sulfide, and 0.12 micromol/ml for thiosulfate. Based on the above results, we concluded that thiosulfate in urine is the only indicator to prove hydrogen sulfide poisoning in non-fatal cases, while the analysis of sulfide in fatal cases should be accompanied by the measurement of thiosulfate in blood.

A case of drowning linked to ingested sulfides--a report with animal experiments

An adult male was found dead beneath a pool of sewage in the pump room of a fish market. Autopsy revealed the cause of death to be suffocation after aspirating sewage into the respiratory tract. Since hydrogen sulfide gas was detected in the atmosphere at the scene of the accident, gas poisoning was suspected and toxicological analysis of sulfides in body tissues was performed. The concentrations of sulfides in the blood, lung and kidney were 0.95 mumol@ml, 0.22 and 0.38 mumol/g, respectively. These values were remarkably higher than those in previously reported cases involving exposure to hydrogen sulfide gas. Therefore, oral intake of sulfides was assumed and the distribution of sulfides in tissues following oral administration of sodium sulfide solution was examined by means of animal experiments using rats. The concentration of sulfides in the blood from rats following oral intake was much higher than that seen following gas exposure. Based on these results, we concluded that the victim had been exposed to hydrogen sulfide gas and had then collapse into a pool of sewage containing sulfides. The sulfides which were distributed throughout the body tissues had mainly issued from the alimentary tract prior to death by drowning.

Hydrogen sulfide poisoning: management and complications

Hydrogen sulfide poisoning is a rare but devastating injury. Four of 8 cases of toxic inhalation of hydrogen sulfide are presented with special attention to the life-threatening complications. Four patients died at the scene of the accident and the remaining 4 had been hospitalized in the Intensive Care Unit (ICU). One patient died in the hospital from cardiogenic pulmonary edema and circulatory failure (pulmonary wedge pressure > 30 mmHg) and 3 patients left the hospital in good health although they presented serious complications. One of them left the hospital with a temporary pacemaker, and 1 of the 2 others died after two months owing to myocardial infarction. The authors discuss in detail the clinical features of this condition and emphasize the need for urgent and appropriate therapy as well as the need for safe environmental conditions.

Hyper rigs

What's red and white and huge all over? Monster ambulances built by Braun Northwest of Chehalis, Wash., for a Russian mining company.

Occupational fatality and persistent neurological sequelae after mass exposure to hydrogen sulfide

Exposure to hydrogen sulfide (H2S) has been associated with death as well as survival following coma with or without hypoxic brain damage. The release of H2S at a beachfront construction site led to the emergency evaluation and treatment of 37 people, with six admissions and one death. At least one victim, who underwent extensive therapy with hyperbaric oxygen, developed persistent neurological sequelae. Despite increased awareness of the potentially life-threatening consequences of exposure to H2S, significant poisoning continues to occur, even in workplaces where the hazards are well-known and can be avoided. Recommended therapy includes nitrites, hyperbaric oxygen, and supportive care, but documentation of efficacy is lacking. Because patients with chronic neurological sequelae after acute H2S exposure continue to be reported, we suggest that any survivor of H2S poisoning who presents in coma or who manifests objectively verifiable evidence of neurotoxicity on physical examination or lab testing should undergo baseline and annual neurological and neuropsychological testing for at least five years. This approach could standardize and enhance our knowledge of, and ability to detect, the subtle but permanent alterations of central nervous system function that follow H2S exposure.

[Hyperbaric oxygen for hydrogen sulfide poisoning]

Hydrogen sulfide (H2S) is a toxic gas produced in decaying substances containing organic sulfur. Exposure to the gas causes severe disturbances in the central nervous and respiratory systems. The mechanism of toxicity is disruption of the electron transport chain in mitochondria, resulting in intracellular hypoxia. Treatment of H2S poisoning includes mechanical ventilation with 100% oxygen and immediate administration of sodium nitrate. Treatment with hyperbaric oxygen (HBO) has been studied in animal models, and has also been used in a number of patients. However, the clinical effectiveness of this mode of therapy has not been clearly proven. Having recently treated a case of H2S poisoning, we suggest HBO to reduce mortality.

[Acute poisoning caused by hydrogen sulphide: clinical features of 3 cases]

We describe three cases of acute intoxication by hydrogen sulphide which were produced after remaining between 50 and 60 minutes inside a cellulose tank. The three patients had loss of conscience. One of the patients developed a persistent vegetative state; another patient recovered although with neurological post-anoxic sequelas and the third case completely recovered one week after his hospitalization. The patients underwent symptomatic treatment and the environmental concentrations of hydrogen sulphide were measured at the site of the accident. Finally, the application of preventive measures is stressed.

A fatal disaster case based on exposure to hydrogen sulfide--an estimation of the hydrogen sulfide concentration at the scene

Four adult men fell into an artificial lake which was being used to raise flatfish, after a water pipe had been connected to a tube allowing seawater to flow into the lake. Forensic autopsies were carried out on three of the four men, who died soon after the incident. From autopsy findings, the cause of death was diagnosed to be suffocation after aspirating seawater in the three victims. To clarify why the men fell into the lake, a chemical analysis for hydrogen sulfide was carried out using the extractive alkylation technique combined with gas chromatography/mass spectrometry. The sulfide was detected as its derivative, bis(pentafluorobenzyl)sulfide, in body tissues taken from all the victims, and the concentration of hydrogen sulfide gas at the scene was estimated as having been nearly fatal.

Use of hyperbaric oxygen in toxicology

HBO has become recognized as a potential treatment for a variety of toxins. HBO is helpful because it provides an excess of dissolved oxygen, which not only can sustain life in the absence of hemoglobin, but in some cases can actually increase the clearance of toxins. In addition, it is now apparent that HBO serves more complex roles in toxicological injuries, such as modifying PMN-endothelial interactions and preventing oxidative tissue injury. The major drawback of HBO therapy is the lack of controlled clinical trials, partly due to the rarity of most of the toxins discussed. In fact, the field of hyperbaric medicine has come under increasing criticism for this failure. There is a physiologic basis for use of HBO in the toxins discussed. Unfortunately, only for CO is patient volume adequate for studies to document efficacy. Regarding the other toxins mentioned, the use of HBO should be reserved for carefully selected cases in which patients have failed routine care or are at risk for delayed effects.

[Hydrogen sulfide poisoning in a farmer]

A case of hydrogen sulfide intoxication in a farmer is described. He collapsed in a mobile tank, recently used for spreading manure and was comatose on arrival at the hospital. He survived, but still suffers from a toxic/anoxic psychosyndrome. On site measurements showed high concentrations of hydrogen sulfide. The treatment is controversial and is discussed.

Case report: profound neurobehavioral deficits in an oil field worker overcome by hydrogen sulfide

A 24-year-old oil well tester was rendered semiconscious by hydrogen sulfide (H2S). He received oxygen and was hospitalized but released in 30 minutes. The next day, nausea, vomiting, diarrhea, and incontinence of urine and stool led to rehospitalization. These problems and leg shaking, dizziness, sweating, trouble sleeping, and nightmares prevented his return to work. A physical examination, chest x-ray, and pulmonary function tests were normal 39 months after the episode but vibration sense was diminished. Two choice visual reaction times were delayed. Balance was highly abnormal (5 to 6 cm/sec) with eyes closed. Blink reflex latency was slow (R-1 17.5 msec versus normal 14.3 msec). Numbers written on finger tips were not recognized. Verbal and visual recall were impaired but overlearned memory was intact. Cognitive functions measured by Culture Fair, block design, and digit symbol were impaired. Perceptual motor was slow. Scores for confusion, tension-anxiety, depression, and fatigue were elevated and vigor was reduced. Forty-nine months after exposure his reaction time, sway speed, and color vision had not improved. His recall and his cognitive, constructional, and psychomotor speeds had improved but remained abnormal. These deficits are most likely due to H2S. Similar testing of other survivors is recommended.

[Extrapyramidal syndrome induced by chemical substances]

Extrapyramidal signs are frequently observed in toxic diseases due to environmental and industrial chemical substances. The predominant manifestations are Parkinsonism and less frequently tremor. Parkinsonism has been described among the toxic diseases due to carbon monoxide, hydrogen sulfide, and hydrogen cyanide. In these diseases, Parkinsonism used to appear in the recovery stage from coma in the severe cases. This was also true in methyl alcohol poisoning. The extrapyramidal signs are usually symmetrical. Akinesia and rigidity are main features. Tremor is absent or mild. Levodopa and the other antiparkinsonian drugs are not so effective. Brain CT studies have revealed symmetrical low density areas in the globus pallidus and putamen. On the other hand, postural tremor is main neurological findings in the poisonings by inorganic mercury and tetraethyl lead. In general, tremor in the toxic disease is reported to be self-limited.

[Toxicological findings in a death involving hydrogen sulfide]

A case of fatal hydrogen sulfide poisoning in a sewage disposal plant is described. Hydrogen sulfide levels were determined in several postmortem body tissues and fluids using gas chromatography with a flame photometric detection (GC-FPD). The concentrations of hydrogen sulfide in the blood, muscle, liver, lung, kidney, heart and brain were 0.305, 0.690, 1.089, 1.338, 1.170, 1.366 and 0.875 (micrograms/g or ml), respectively. The results are discussed in the light of the existing literature on the toxicological significance of hydrogen sulfide concentrations.

Fatalities attributed to entering manure waste pits--Minnesota, 1992

In August 1992, four farm workers in Minnesota died in two separate incidents after entering manure waste pits: two were poisoned by hydrogen sulfide gas, and two were asphyxiated. The Minnesota Fatality Assessment and Control Evaluation (FACE) program was notified of the incidents by the state Occupational Safety and Health Administration and the Minnesota Farming Health Project, respectively. This report summarizes the investigations of these two incidents by the Minnesota FACE program and CDC's National Institute for Occupational Safety and Health (NIOSH) FACE personnel.

Toxicology of hydrogen sulfide

Significant progress has been made in determining the action of sulfide on the primary target organs. It is reasonably clear that sulfide causes both K(+)-channel-mediated hyperpolarization of neurons and potentiation of other inhibitory mechanisms. It is not clear whether these processes are similar to those that occur in anoxia. Changes in perinatal and adult brain neurotransmitter content and release may be related to clinical impairment of cognition. H2S exposures at concentrations below the current occupational limits cause physiological changes in pulmonary function, thus suggesting that asthmatics are at risk. Studies of fetal and neonatal brain tissue have shown an abnormal development, and the long-term consequences of these neuronal changes have not yet been assessed. Finally, new approaches to therapy are required, such as the use of agents that actively remove sulfide from its sites of action. This may prove more useful in preventing some of the long-term adverse sequelae than the use of nitrites and hyperbaric O2, although the latter should be used in cases of pulmonary edema.

Delayed neuropsychiatric sequelae after acute hydrogen sulfide poisoning: affection of motor function, memory, vision and hearing

A shipyard worker was poisoned by hydrogen sulfide (H2S), and rescued after 15-20 min. He regained consciousness after 2 days. Three days later his condition deteriorated, and he was more or less comatose for a month. When he woke up, he was amnesic, nearly blind, had reduced hearing, and had a moderate spastic tetraparesis and ataxia. Two months after the accident, he had greatly improved. Audiograms showed hearing loss with maximum at 2000 Hz and significantly poorer speech discrimination. EEG showed generalized dysrhythmia. At follow-up 5 years later he had not been able to resume his work, and had slight motor, memory and visual symptoms. CT and MRI showed slight cerebral atrophy. EEG and evoked responses were normal.

Brain damage caused by hydrogen sulfide: a follow-up study of six patients

Hydrogen sulfide (H2S) poisoning involves a risk of hypoxic brain damage. Six patients who lost consciousness due to H2S poisoning are described. The symptoms varied from anosmia in the patient with the shortest but highest exposure to delayed neurological deterioration in the patient with the longest exposure. The two patients with the most serious symptoms developed pulmonary edema, which may have prolonged the hypoxia. The patients were reexaminated 5 years or more after the poisoning. The five patients who had been unconscious in H2S atmosphere for from 5 to 15-20 min showed persisting impairment at neurological and neuropsychological re-examination. Memory and motor function were most affected. One patient was seriously demented. Recent reports of large groups of H2S-poisoned workers probably underestimate the risk of sequelae, due to the inclusion of cases with exposure of short duration and lack of follow-up.

Dithiothreitol liberates non-acid labile sulfide from brain tissue of H2S-poisoned animals

Acid-labile sulfide measured by conventional gas dialysis and ion chromatography with electrochemical detection accounts for only a proportion of the total sulfide present in brain tissue after poisoning with NaHS, an H2S precursor. Dithiothreitol (DTT) displaced additional measurable sulfide not detectable by the conventional techniques from NaHS-poisoned brain tissue. Sulfide liberation by DTT was dose-dependent and maximal at higher DTT concentration (10 and 30 mM) and was thought to represent non-acid labile sulfide. Dithiothreitol was also found to be significantly protective against H2S poisoning. Furthermore, in vitro inhibition by sulfide of monoamine oxidase (MAO) was reversed by DTT, thus suggesting a molecular mechanism consistent with known persulfide chemistry. Persulfide formation may thus underlie some aspects of hydrogen sulfide neurotoxicity. The rational development of antidotes for use in H2S poisoning may thus have to be centered on strategies concentrating on known thiol, disulfide and persulfide chemistry.