Hydrogen sulfide can be found in many environments, and toxicity can arise from both direct contact and as the chemical enters the bloodstream. At high levels of toxicity, rapid clinical deterioration can occur, highlighting the need for prompt diagnosis and management. This activity reviews the evaluation and treatment of hydrogen sulfide toxicity and explains the role of the interprofessional team in evaluating and treating patients with this condition.
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Objectives:
Review the epidemiology of hydrogen sulfide toxicity.
Outline appropriate evaluation of hydrogen sulfide toxicity.
Summarize the management options available for hydrogen sulfide toxicity.
Explain the importance of improving coordination among the interprofessional team to enhance the delivery of care for patients with hydrogen sulfide toxicity.
Hydrogen sulfide is a highly flammable, colorless, and toxic gas found naturally in sewage, swamps, manure gas, hot springs, geysers, and volcanoes. It is found in the oil and gas industries and is used in activities such as food processing, paper mills, and tanneries. It is also found in some homemade cleaning mixtures that are occasionally employed in suicide attempts.[1][2][3][4][5][6][7] Hydrogen sulfide poisoning usually occurs by inhalation. Local irritant effects are not that lethal. Low-level exposure usually produces mucous membrane and skin irritation, while high-level exposure produces fatal toxicity.
Hydrogen sulfide toxicity typically results from gaseous exposure and acts as an irritant initially and later acts by inhibiting mitochondrial respiration. Inhalation is the most common route of administration for the toxic substance to enter the bloodstream though it can be absorbed through the skin as well.[2]
The combustible nature of the gas increases the risk of explosions and burns as another mechanism of injury. Hydrogen sulfide is heavier than air and therefore tends to accumulate and concentrate near the floors of poorly ventilated rooms rather than disperse into the air.[1][8]
Hydrogen sulfide toxicity results mostly from unintentional exposure. Cases have steadily increased in the United States from the 1990s to 2019. After being popularized as a method of suicide in Japan in 2007, suicides increased significantly before strongly trending downward.[9][10] Approximately 80% of suicide attempts have ensued in toxicity of first responders and civilians near the scene.[11] Most cases occur in those greater than 20 years of age. Less than 1% of unintentional cases result in death, while the mortality rate in intentional cases exceeds 50%.[12][13][14][15][16]
Hydrogen sulfide poisoning usually occurs by inhalation, local irritant effects result in direct irritation to the eyes, causing conjunctival injection initially and the corneal injury eventually. When inhaled, it leads to pulmonary injury presenting as hemorrhagic pulmonary edema. Hydrogen sulfide inhibits mitochondrial cytochrome oxidase by making a complex bond to the ferric moiety of the protein, therefore arrest aerobic metabolism. Once it enters the bloodstream and passes the blood-brain barrier, neurotoxic effects can be seen, namely dizziness, seizure, coma, and ultimately death.[2][17][18] In brief, hydrogen sulfide is a known pulmonary irritant and asphyxiant that primarily causes respiratory and neurological clinical manifestations when inhaled.[19] High concentrations (more than 700ppm) have the potential to cause sudden death.
Animal studies have reported marked disruption in the lung surfactant activity, increased lactate dehydrogenase (LDH) activity, and increased total protein in the bronchoalveolar lavage fluid.[19][20]
The mechanism of action of hydrogen sulfide toxicity is similar to that of cyanide. Oxidative phosphorylation in the electron transport chain during aerobic glucose metabolism is disrupted via inhibition of cytochrome c oxidase. Cells, therefore, largely are diverted to anaerobic metabolism, producing metabolic acidosis due to lactate accumulation.[2][17][18]
As many toxic gases overlap in terms of toxic effects, history is imperative to help determine the specific gas causing the toxicity. Occupational history and recent local travel history will help differentiate, i.e., working in a petroleum plant or as a sewage inspector, or traveling to a natural hot spring or volcano. Patients may typically report a strong “rotten egg” smell. However, it is important to note that hydrogen sulfide rapidly desensitizes olfactory nerves, and after prolonged exposure, patients may fail to recall the malodorous scent. Lack of malodor should not be relied upon as a definitive exclusion of hydrogen sulfide toxicity.
Exposure can be low, high, or very high level. chronic low-level exposure presents with irritation to mucous membranes, headache, insomnia, dizziness, and fatigue. High-level exposure presents with cough, dyspnea, hemoptysis, nausea, vomiting, and vertigo. Very high-level exposure presents myocardial infarction, loss of consciousness, seizures, and cardiopulmonary arrest. Clinical examination findings for low dose exposure include conjunctivitis, green-gray line on the gingiva, and phryngitis. Clinical examination findings for high-level exposure include bradycardia, agitation, cyanosis, and acute lung injury. At higher doses, pulmonary edema, hemoptysis (hemorrhagic pulmonary edema), and delayed corneal injury may occur. Higher doses may also induce neurological symptoms of seizure, coma, and ultimately death.[2][6][7][17][18][21]
The diagnostic workup is largely negative. However, in cases of pulmonary edema, this can be seen on an X-ray of the chest or on a bedside ultrasound. Elevated lactate is another finding. However, this should be considered in conjunction with the history and clinical examination findings as elevated lactate has numerous causes. Arterial blood gas (ABG) analysis or venous blood gas (VBG) analysis shows metabolic acidosis secondary to lactate. An electrocardiogram (ECG) should be obtained to assess for myocardial ischemia or infarction.[17][18][22]
Initial treatment in an awake patient includes removal from exposure, including removal of clothing, and administration of high flow oxygen. Intravenous fluids and vasopressors should be administered to hypotensive patients. Correction of acidosis based on arterial blood gases and lactate dehydrogenase levels should be done. In higher toxic doses where a patient may be altered or in severe respiratory distress secondary to pulmonary edema, treatment consists of sodium nitrite administration of 300 mg intravenous given over two to four minutes. Sodium nitrite causes methemoglobin to accumulate at low levels. This promotes the conversion of the sulfide to sulfmethemoglobin, which is less toxic than the sulfide. This medication is most effective if given within minutes, as hydrogen sulfide toxicity escalates rapidly. After treatment with sodium nitrite, levels of methemoglobin should be checked within 30-60 minutes, with ideal levels below 30%. If levels of methemoglobin become concerning, methylene blue may be administered. Other than sodium nitrite administration for the treatment of hydrogen sulfide, there is some evidence to suggest hyperbaric oxygen can help improve the delivery of oxygen to end organs. Another medication, cobinamide, has shown promise in animal models for hydrogen sulfide and cyanide toxicity.[17][18][22][23][24][25][26] In severe cases, intubation should be done for airway protection and ventilation.
Other gaseous toxicities can present with similar symptoms. Following differentials should be considered when assessing a hydrogen sulfide toxicity patient.
Hydrocarbons commonly cause dyspnea and cough and may lead to respiratory distress. Infiltrates can be seen on a chest X-ray. CNS depression and myocardial dysfunction can also occur. [27]
Cyanide has a similar mechanism of action as hydrogen sulfide, and patients may also have an overlap of some symptoms, including seizures, tachypnea, and coma. Cyanide, however, is more likely to also present with headache, nausea, vomiting, arrhythmias, cyanosis, and renal and hepatic failure. Cyanide classically has a smell of almonds rather than the rotten egg smell of hydrogen sulfide. [28]
Patients with carbon monoxide poisoning and methemoglobinemia can also present with headache, dyspnea, and confusion but are also more likely to have symptoms of chest pain, nausea, and vomiting. Context is key when differentiating many of these toxic gases with overlapping symptoms. Co-oximetry can help rule out carbon monoxide poisoning and methemoglobinemia. [29] [30] [31]
Mild exposures have a good prognosis. Large exposures can lead to serious complications and death. There is some evidence that long-term exposure or large exposure can lead to chronic neurocognitive deficits, likely secondary to oxygen deprivation after the loss of consciousness.[22][25] Exposures of more than 700 ppm can cause cardiopulmonary arrest.
Complications of hydrogen sulfide toxicity usually occur with high-dose exposure. These include:
Acute respiratory distress syndrome
Acute myocardial infarction
Delayed neuropsychiatric sequelae [22] [25] [32]
The main form of deterrence is to avoid areas known to contain hydrogen sulfides, such as volcanoes, sewers, swamps, and other areas of natural gas.[2][25] In industries where employees are expected to work around toxic substances, proper personal protective equipment (PPE) should be donned to avoid toxicity. Chief among these is to wear a respirator mask to avoid inhalation, which is the most frequent and direct way for severe toxicity to occur.[25][33]
Hydrogen sulfide toxicity can be difficult to diagnose as it is a colorless gas with a rapidly desensitizing scent. Symptoms can overlap with other toxic gaseous exposures. It is important that first-responders obtain a thorough history so as to clue providers into the likely diagnosis upon arrival to the emergency department. Once the patient arrives, an astute provider will look for keys to diagnosis such as the location of toxicity, work environment, the possible scent of rotten egg, and assess these clues in conjunction with patient symptoms and signs.[25]
It is imperative the patient is decontaminated so as not to affect other staff, and treatment should begin promptly as hydrogen sulfide toxicity can be rapidly decompensating and ultimately ensue in death. The poison control center should be notified immediately for greater expertise in diagnosing and treating this rare condition.[13] The patient should immediately be given supplemental oxygen for any signs of respiratory distress or hypoxia, and the clinical pharmacist may aid in the dosing of appropriate medical management.[22] [Level 5]
Disclosure: Anthony Sawaya declares no relevant financial relationships with ineligible companies.
Disclosure: Ritesh Menezes declares no relevant financial relationships with ineligible companies.
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CAS# 7783-060-4
UN# 1053
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Synonyms include dihydrogen sulfide, sulfur hydride, sulfurated hydrogen, hydrosulfuric acid, "sewer gas," "swamp gas," hepatic acid, sour gas, and "stink damp."
Hydrogen sulfide is a colorless, flammable, highly toxic gas. It is shipped as a liquefied, compressed gas. It has a characteristic rotten-egg odor that is detectable at concentrations as low as 0.5 ppb.
Inhalation is the major route of hydrogen sulfide exposure. The gas is rapidly absorbed by the lungs. The odor threshold (0.5 ppb) is much lower than the OSHA ceiling (20 ppm). However, although its strong odor is readily identified, olfactory fatigue occurs at high concentrations and at continuous low concentrations. For this reason, odor is not a reliable indicator of hydrogen sulfide's presence and may not provide adequate warning of hazardous concentrations. Hydrogen sulfide is slightly heavier than air and may accumulate in enclosed, poorly ventilated, and low-lying areas.
Children exposed to the same levels of hydrogen sulfide as adults may receive larger doses because they have greater lung surface area:body weight ratios and increased minute volumes:weight ratios. In addition, they may be exposed to higher levels than adults in the same location because of their short stature and the higher levels of hydrogen sulfide found nearer to the ground. Children may be more vulnerable to corrosive agents than adults because of the relatively smaller diameter of their airways.
Skin/Eye ContactProlonged exposure to hydrogen sulfide, even at relatively low levels, may result in painful dermatitis and burning eyes. Direct contact with the liquefied gas can cause frostbite. Absorption through intact skin is minimal.
IngestionBecause hydrogen sulfide is a gas at room temperature, ingestion is unlikely to occur.
Hydrogen sulfide is produced naturally by decaying organic matter and is released from sewage sludge, liquid manure, sulfur hot springs, and natural gas. It is a by-product of many industrial processes including petroleum refining, tanning, mining, wood- pulp processing, rayon manufacturing, sugar-beet processing, and hot-asphalt paving. Hydrogen sulfide is used to produce elemental sulfur, sulfuric acid, and heavy water for nuclear reactors.
OSHA ceiling = 20 ppm
OSHA maximum peak = 50 ppm (10 minutes, once, no other exposure)
NIOSH IDLH (immediately dangerous to life or health) = 100 ppm
AIHA ERPC-2 (emergency response planning guideline) (maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action) = 30 ppm.
Description: Colorless gas with odor of rotten eggs
Warning properties: Not dependable; characteristic rotten-egg odor detectable at about 0.5 ppb, but olfactory nerve fatigue occurs in 2 to 15 minutes at concentrations over 100 ppm
Molecular weight: 34.1 daltons
Boiling point (760 mm Hg): -77°F (-60.3°C)
Vapor pressure: >760 mm Hg at 68°F (20°C)
Gas density: 1.2 (air = 1)
Water solubility: Slightly water soluble (0.4% at 68°F [20°C])
Flammability: Highly flammable and explosive between 4% and 45% (concentration in air); may travel to a source of ignition and flash back. Burns to produce a toxic gas, sulfur dioxide.
Hydrogen sulfide reacts with strong oxidizers, strong nitric acid, and metals.
Hydrogen sulfide's can cause inhibition of the cytochrome oxidase enzyme system resulting in lack of oxygen use in the cells. Anaerobic metabolism causes accumulation of lactic acid leading to an acid-base imbalance. The nervous system and cardiac tissues are particularly vulnerable to the disruption of oxidative metabolism and death is often the result of respiratory arrest. Hydrogen sulfide also irritates skin, eyes, mucous membranes, and the respiratory tract. Pulmonary effects may not be apparent for up to 72 hours after exposure.
Children do not always respond to chemicals in the same way that adults do. Different protocols for managing their care may be needed.
CNSCNS injury is immediate and significant after exposure to hydrogen sulfide. At high concentrations, only a few breaths can lead to immediate loss of consciousness, coma, respiratory paralysis, seizures, and death. CNS stimulation may precede CNS depression. Stimulation manifests as excitation, rapid breathing, and headache; depression manifests as impaired gait, dizziness, and coma, possibly progressing to respiratory paralysis and death. In addition, decreased ability to smell hydrogen sulfide occurs at concentrations greater than 100 ppm.
RespiratoryInhaled hydrogen sulfide initially affects the nose and throat. Low concentrations (50 ppm) can rapidly produce irritation of the nose, throat, and lower respiratory tract. Pulmonary manifestations include cough, shortness of breath, and bronchial or lung hemorrhage. Higher concentrations can provoke bronchitis and cause accumulation of fluid in the lungs, which may be immediate or delayed for up to 72 hours. Lack of oxygen may result in blue skin color.
Children may be more vulnerable to corrosive agents than adults because of the relatively smaller diameter of their airways. Children may also be more vulnerable to gas exposure because of increased minute ventilation per kg and failure to evacuate an area promptly when exposed.
CardiovascularHigh-dose exposures may cause insufficient cardiac output, irregular heartbeat, and conduction abnormalities.
RenalTransient renal effects include blood, casts, and protein in the urine. Renal failure as a direct result of hydrogen sulfide toxicity has not been described, although it may occur secondary to cardiovascular compromise.
GastrointestinalSymptoms may include nausea and vomiting.
DermalProlonged or massive exposure may cause burning, itching, redness, and painful inflammation of the skin. Exposure to the liquified gas can cause frostbite injury.
OcularEye irritation may result in inflammation (i.e., keratoconjunctivitis) and clouding of the eye surface. Symptoms include blurred vision, sensitivity to light, and spasmodic blinking or involuntary closing of the eyelid.
Potential SequelaeInflammation of the bronchi can be a late development. Survivors of severe exposure may develop psychological disturbances and permanent damage to the brain and heart. The cornea may be permanently scarred.
Hydrogen sulfide does not accumulate in the body. Nevertheless, repeated or prolonged exposure has been reported to cause low blood pressure, headache, nausea, loss of appetite, weight loss, ataxia, eye-membrane inflammation, and chronic cough. Neurologic symptoms, including psychological disorders, have been associated with chronic exposure. Chronic exposure may be more serious for children because of their potential longer latency period.
CarcinogenicityHydrogen sulfide has not been classified for carcinogenic effects.
Reproductive and Developmental EffectsThere is some evidence to suggest that exposure to hydrogen Developmental Effects sulfide may be associated with an increased risk of spontaneous abortion. No information was located pertaining to placental transfer of hydrogen sulfide or to excretion of hydrogen sulfide in breast milk. There are no studies of developmental effects in humans exposed to hydrogen sulfide. However, results from animal studies suggest that hydrogen sulfide may be a developmental neurotoxicant. Hydrogen sulfide is not listed in TERIS or in Shepard's Catalog of Teratogenic Agents. It is also not included in Reproductive and Developmental Toxicants, a 1991 report published by the U.S. General Accounting Office (GAO) that lists 30 chemicals of concern because of widely acknowledged reproductive and developmental consequences.
Rescuers should be trained and appropriately attired before entering the Hot Zone. If the proper equipment is not available, or if prehospital staff have not been trained in its use, assistance should be obtained from a local or regional HAZMAT team or other properly equipped response organization.
Rescuer ProtectionHydrogen sulfide is an extremely rapidly acting, highly toxic gas. Fatalities have occurred to rescuers entering the hot zone.
Respiratory Protection: Positive-pressure, self-contained breathing apparatus (SCBA) is recommended in response situations that involve exposure to potentially unsafe levels of hydrogen sulfide.
Skin Protection: Chemical-protective clothing is not generally required because hydrogen sulfide gas is not absorbed through the skin, and skin irritation is rare. Direct contact with the liquefied gas can cause frostbite.
Rescuers should have a safety line during rescue operations because of the extremely rapid toxic action of hydrogen sulfide.
ABC RemindersQuickly access for a patent airway, ensure adequate respiration and pulse. If trauma is suspected, maintain cervical immobilization manually and apply a cervical collar and a backboard when feasible.
Victim RemovalIf victims can walk, lead them out of the Hot Zone to the Decontamination Zone. Victims who are unable to walk may be removed on backboards or gurneys; if these are not available, carefully carry or drag victims to safety.
Consider appropriate management of chemically contaminated children, such as measures to reduce separation anxiety if a child is separated from a parent or other adult.
Patients exposed only to hydrogen sulfide gas who have no skin or eye irritation do not need decontamination. They may be transferred immediately to the Support Zone. Other patients will require decontamination as described below.
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Rescuer ProtectionIf exposure levels are determined to be safe, decontamination may be conducted by personnel wearing a lower level of protection than that worn in the Hot Zone (described above).
ABC RemindersQuickly access for a patent airway, ensure adequate respiration and pulse. Stabilize the cervical spine with a collar and a backboard if trauma is suspected. Administer supplemental oxygen as required. Assist ventilation with a bag-valve-mask device if necessary.
Basic DecontaminationVictims who are able may assist with their own decontamination. Remove and double-bag contaminated clothing.
Handle frostbitten skin and eyes with caution. Wrap the affected part gently in blankets. Let the circulation reestablish itself naturally. Encourage the victim to exercise the affected part while it is being warmed.
Flush exposed skin and hair with water for 3 to 5 minutes. Use caution to avoid hypothermia when decontaminating children or the elderly. Use blankets or warmers when appropriate.
Do not irrigate frostbitten eyes. Otherwise, irrigate exposed or irritated eyes with plain water or saline for at least 5 minutes. Eye irrigation may be carried out simultaneously with other basic care and transport. Remove contact lenses if easily removable without additional trauma to the eye. If a corrosive material is suspected or if pain or injury is evident, continue irrigation while transferring the victim to the support zone.
Consider appropriate management of chemically contaminated children, such as measures to reduce separation anxiety if a child is separated from a parent or other adult. If possible, seek assistance from a child separation expert.
Transfer to Support ZoneAs soon as basic decontamination is complete, move the victim to the Support Zone.
Be certain that victims have been properly decontaminated (see Decontamination Zone above). Victims who have undergone decontamination or who have been exposed only to hydrogen sulfide gas pose no serious risks of secondary contamination. In such cases, Support Zone personnel require no specialized protective gear.
ABC RemindersQuickly access for a patent airway. If trauma is suspected, maintain cervical immobilization manually and apply a cervical collar and a backboard when feasible. Ensure adequate respiration and pulse. Administer supplemental oxygen as required and establish intravenous access if necessary. Place on a cardiac monitor.
Additional DecontaminationContinue irrigating exposed skin and eyes, as appropriate.
Advanced TreatmentIn cases of respiratory compromise secure airway and respiration via endotracheal intubation. If not possible, perform cricothyroidotomy if equipped and trained to do so.
Treat patients who have bronchospasm with aerosolized bronchodilators. The use of bronchial sensitizing agents in situations of multiple chemical exposures may pose additional risks. Consider the health of the myocardium before choosing which type of bronchodilator should be administered. Cardiac sensitizing agents may be appropriate; however, the use of cardiac sensitizing agents after exposure to certain chemicals may pose enhanced risk of cardiac arrhythmias (especially in the elderly). Hydrogen sulfide poisoning is not known to pose additional risk during the use of bronchial or cardiac sensitizing agents.
Consider racemic epinephrine aerosol for children who develop stridor. Dose 0.25-0.75 mL of 2.25% racemic epinephrine solution in 2.5 cc water, repeat every 20 minutes as needed, cautioning for myocardial variability.
Patients who are comatose, hypotensive, or are having seizures or cardiac arrhythmias should be treated according to advanced life support (ALS) protocols.
If frostbite is present, treat by rewarming
in a water bath at a temperature of 102 to 108°F (40
to 42°C) for 20 to 30 minutes and continue until a flush
has returned to the affected area.
Nitrite therapy (found in the cyanide antidote kit) has been
suggested as a therapy for hydrogen sulfide exposure. Amyl
nitrite is given by inhalation (for 30 seconds every minute
until an intravenous line is established) followed by intravenous
sodium nitrite (300 mg over absolutely no less than 5 minutes).
This may aid recovery by forming sulfmethemoglobin, thus removing
sulfide from combination in tissue. It is not necessary to
use the sodium thiosulfate component of the cyanide antidote
kit. The antidotal efficacy of nitrite therapy is controversial,
but is currently recommended if it can be started shortly
after exposure. However, there is only anecdotal evidence
that nitrite therapy is effective, and victims of hydrogen
sulfide poisoning have survived without sequelae after supportive
care alone. The usefulness of nitrite therapy given beyond
the first few minutes after exposure is questionable. Nitrite
therapy should not be allowed to interfere with the establishment
of adequate ventilation and oxygenation.
Only decontaminated patients or patients not requiring decontamination should be transported to a medical facility. "Body bags" are not recommended.
Report to the base station and the receiving medical facility the condition of the patient, treatment given, and estimated time of arrival at the medical facility.
Consult with the base station physician or regional poison control center for further advice regarding triage of multiple victims.Patients with evidence of significant exposure (e.g., breathing difficulties, unconsciousness, seizures, or collapse) should be transported to a medical facility for evaluation. Patients who have minor or transient irritation of the eyes or throat may be discharged from the scene after their names, addresses, and telephone numbers are recorded. They should be advised to seek medical care promptly if symptoms develop or recur (see Patient Information Sheet below).
Patients who have been decontaminated previously and patients exposed only to hydrogen sulfide gas who have no skin or eye irritation may be transferred immediately to the Critical Care Area. Other patients require decontamination as described below.
Be aware that use of protective equipment by the provider may cause fear in children, resulting in decreased compliance with further management efforts.
ABC RemindersEvaluate and support airway, breathing, and circulation. Children may be more vulnerable to corrosive agents than adults because of the smaller diameter of their airways. In cases of respiratory compromise secure airway and respiration via endotracheal intubation. If not possible, surgically create an airway.
Treat patients who have bronchospasm with aerosolized bronchodilators. The use of bronchial sensitizing agents in situations of multiple chemical exposures may pose additional risks. Consider the health of the myocardium before choosing which type of bronchodilator should be administered. Cardiac sensitizing agents may be appropriate; however, the use of cardiac sensitizing agents after exposure to certain chemicals may pose enhanced risk of cardiac arrhythmias (especially in the elderly). Hydrogen sulfide poisoning is not known to pose additional risk during the use of bronchial or cardiac sensitizing agents.
Consider racemic epinephrine aerosol for children who develop stridor. Dose 0.25-0.75 mL of 2.25% racemic epinephrine solution in 2.5 cc water, repeat every 20 minutes as needed, cautioning for myocardial variability.
Patients who are comatose, hypotensive, or have seizures or ventricular arrhythmias should be treated in the conventional manner.
Nitrite therapy (found in the cyanide antidote kit) has been suggested as a therapy for hydrogen sulfide exposure. Amyl nitrite is given by inhalation (for 30 seconds every minute until an intravenous line is established) followed by intravenous sodium nitrite (300 mg over absolutely no less than 5 minutes). This may aid recovery by forming sulfmethemoglobin, thus removing sulfide from combination in tissue. It is not necessary to use the sodium thiosulfate component of the cyanide antidote kit. The antidotal efficacy of nitrite therapy is controversial, but is currently recommended if it can be started shortly after exposure. The usefulness of nitrite therapy given beyond the first few minutes after exposure is questionable. There is only anecdotal evidence that nitrite therapy is effective, and victims of hydrogen sulfide poisoning have survived without sequelae after supportive care alone. Nitrite therapy should not be allowed to interfere with the establishment of adequate ventilation and oxygenation.
Basic DecontaminationPatients who are able may assist with their own decontamination. Remove and double-bag contaminated clothing and personal belongings.
Handle frostbitten skin and eyes with caution. Place frostbitten skin in warm water, about 108°F (42°C). Let the circulation reestablish itself naturally. Encourage the victim to exercise the affected part while it is being warmed.
Flush exposed skin and hair with plain water for 5 minutes, preferably under a shower. Use caution to avoid hypothermia when decontaminating children or the elderly. Use blankets or warmers when appropriate.
Do not irrigate frostbitten eyes. Otherwise, irrigate exposed eyes for at least 5 minutes. Remove contact lenses if easily removable without additional trauma to the eye. An ophthalmic anesthetic may be necessary to alleviate blepharospasm, and lid retractors may be required to allow adequate irrigation under the eyelids. Continue irrigation while transporting the patient to the Critical Care Area.
Be certain that appropriate decontamination has been carried out (see Decontamination Area above).
ABC RemindersEvaluate and support airway, breathing, and circulation as in ABC Reminders above. Children may be more vulnerable to corrosive agents than adults because of the smaller diameter of their airways. Establish intravenous access in seriously symptomatic patients. Continuously monitor cardiac rhythm.
Patients who are comatose, hypotensive, or have seizures or cardiac arrhythmias should be treated in the conventional manner.
Inhalation ExposureAdminister supplemental oxygen by mask to patients who have respiratory symptoms. Treat patients who have bronchospasm with aerosolized bronchodilators. The use of bronchial sensitizing agents in situations of multiple chemical exposures may pose additional risks. Consider the health of the myocardium before choosing which type of bronchodilator should be administered. Cardiac sensitizing agents may be appropriate; however, the use of cardiac sensitizing agents after exposure to certain chemicals may pose enhanced risk of cardiac arrhythmias (especially in the elderly). Hydrogen sulfide poisoning is not known to pose additional risk during the use of bronchial or cardiac sensitizing agents.
Consider racemic epinephrine aerosol for children who develop stridor. Dose 0.25-0.75 mL of 2.25% racemic epinephrine solution in 2.5 cc water, repeat every 20 minutes as needed, cautioning for myocardial variability.
Observe patients for 24 hours, repeating appropriate tests and chest examinations as needed. Follow-up as clinically indicated.
Skin ExposureIf concentrated hydrogen sulfide was in contact with the skin, chemical burns may result; treat as thermal burns. If the liquefied compressed gas is released and contacts the skin, frostbite may result. If a victim has frostbite, treat by rewarming affected areas in a water bath at a temperature of 102 to 108°F (40 to 42°C) for 20 to 30 minutes and continue until a flush has returned to the affected area.
Eye ExposureContinue irrigation for at least 5 minutes. Test visual acuity. Examine the eyes for corneal damage and treat appropriately. Immediately consult an ophthalmologist for patients who have severe corneal injuries.
Antidotes and Other TreatmentsNitrite therapy (found in the cyanide antidote kit) has been Other Treatments suggested as a therapy for hydrogen sulfide exposure. Amyl nitrite is given by inhalation (for 30 seconds every minute until an intravenous line is established) followed by intravenous sodium nitrite (300 mg over absolutely no less than 5 minutes). This may aid recovery by forming sulfmethemoglobin, thus removing sulfide from combination in tissue. It is not necessary to use the sodium thiosulfate component of the cyanide antidote kit. The antidotal efficacy of nitrite therapy is controversial, but is currently recommended if it can be started shortly after exposure. The usefulness of nitrite therapy given beyond the first few minutes after exposure is questionable. There is only anecdotal evidence that nitrite therapy is effective, and victims of hydrogen sulfide poisoning have survived without sequelae after supportive care alone. Nitrite therapy should not be allowed to interfere with the establishment of adequate ventilation and oxygenation.
Hyperbaric oxygen therapy is controversial and based on anecdotal evidence. It may be effective for patients with persistent coma in whom other treatments are unsuccessful.
Laboratory TestsRoutine laboratory studies for all symptomatic exposed patients include CBC, blood glucose, and electrolyte determinations. Additional studies for patients exposed to hydrogen sulfide include ECG monitoring and renal-function tests. Chest radiography and pulse oximetry (or ABG measurements) may be helpful in cases of inhalation exposure. If nitrites are used, check methemoglobin levels.
Consider hospitalizing patients who have evidence of systemic toxicity from any route of exposure.
Delayed EffectsPatients who are unconscious or hypotensive should be observed closely for complications including post-hypoxic encephalopathy. Because pulmonary edema may be delayed in onset, patients seriously exposed by inhalation should be monitored for 24 hours. If pulmonary edema is suspected, admit patients to an intensive care unit.
Patient ReleaseAsymptomatic patients who have no evidence of pulmonary edema or CNS or respiratory compromise and no signs of eye irritation may be discharged after 4 to 6 hours of observation with instructions to seek medical care promptly if symptoms develop (see the Hydrogen Sulfide-Patient Information Sheet below).
Follow-upObtain the name of the patient's primary care physician so that the hospital can send a copy of the ED visit to the patient's doctor.
Patients exposed to hydrogen sulfide should be monitored for heart and brain injuries, including evaluation for neurologic deficits.
Patients who have skin or corneal injury should be re-examined within 24 hours.
If a work-related incident has occurred, you may be legally required to file a report; contact your state or local health department.
Other persons may still be at risk in the setting where this incident occurred. If the incident occurred in the workplace, discussing it with company personnel may prevent future incidents. If a public health risk exists, notify your state or local health department or other responsible public agency. When appropriate, inform patients that they may request an evaluation of their workplace from OSHA or NIOSH. See Appendices III and IV for a list of agencies that may be of assistance.
This handout provides information and follow-up instructions for persons who have been exposed to hydrogen sulfide.
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What is hydrogen sulfide?Hydrogen sulfide is an extremely rapidly acting, highly toxic, colorless gas with a rotten-egg odor. It is produced naturally by decaying organic matter and is released from sewage sludge, liquid manure, sulfur hot springs, and natural gas. It is used in several industries and is a by-product of many industrial processes such as oil refining, mining, and rayon manufacturing.
What immediate health effects can be caused by exposure to hydrogen sulfide?Even in small amounts, hydrogen sulfide has a strong rotten-egg odor. However, with continued exposure and at high levels, the poison may deaden a person's sense of smell. If the rotten egg odor is no longer noticeable, it may not necessarily mean that exposure has stopped.
After a serious exposure, symptoms usually begin immediately. At low levels, hydrogen sulfide causes irritation of the eyes, nose, and throat. Moderate levels can cause headache, dizziness, nausea, and vomiting, as well as coughing and difficulty in breathing. Higher levels can cause shock, convulsions, coma, and death. Generally, the more serious the exposure, the more severe the symptoms.
Can hydrogen sulfide poisoning be treated?There is no proven antidote for hydrogen sulfide poisoning, but the effects of hydrogen sulfide can be treated and some exposed persons get well. Persons who have had serious exposures may need to be hospitalized.
Are any future health effects likely to occur?A single small exposure from which a person recovers quickly is not likely to cause delayed or long-term effects. Moderate exposure can cause residual damage and a serious exposure that causes coma or convulsions may damage the brain and heart.
What tests can be done if a person has been exposed to hydrogen sulfide?Specific tests for the presence of hydrogen sulfide in blood and urine generally are not useful to the doctor. If a severe exposure has occurred, blood and urine analyses and other tests may show whether the brain, nerves, heart, or kidneys have been injured. If hydrogen sulfide was inhaled, blood tests and a chest x-ray may be necessary to determine if the lungs have been injured. Testing is not needed in every case.
Where can more information about hydrogen sulfide be found?More information about hydrogen sulfide can be obtained from your regional poison control center; your state, county, or local health department; the Agency for Toxic Substances and Disease Registry (ATSDR); your doctor; or a clinic in your area that specializes in occupational and environmental health. If the exposure happened at work, you may wish to discuss it with your employer, the Occupational Safety and Health Administration (OSHA), or the National Institute for Occupational Safety and Health (NIOSH). Ask the person who gave you this form for help in locating these telephone numbers.
Keep this page and take it with you to your next appointment. Follow only the instructions checked below.
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[ ] Call your doctor or the Emergency Department if you develop any unusual signs or symptoms within the next 24 hours, especially:
[ ] No follow-up appointment is necessary unless you develop any of the symptoms listed above.
[ ] Call for an appointment with Dr.____ in the practice of ________.
When you call for your appointment, please say that you were treated in the Emergency Department at _________ Hospital by________and were advised to be seen again in ____days.
[ ] Return to the Emergency Department/Clinic on ____ (date) at _____ AM/PM for a follow-up examination.
[ ] Do not perform vigorous physical activities for 1 to 2 days.
[ ] You may resume everyday activities including driving and operating machinery.
[ ] Do not return to work for _____days.
[ ] You may return to work on a limited basis. See instructions below.
[ ] Avoid exposure to cigarette smoke for 72 hours; smoke may worsen the condition of your lungs.
[ ] Avoid drinking alcoholic beverages for at least 24 hours; alcohol may worsen injury to your stomach or have other effects.
[ ] Avoid taking the following medications: ________________
[ ] You may continue taking the following medication(s) that your doctor(s) prescribed for you: _______________________________
[ ] Other instructions: ____________________________________ _____________________________________________________
Signature of patient _______________ Date ____________
Signature of physician _____________ Date ____________
If you have questions or concerns, please contact your community or state health or environmental quality department or:
For more information, contact:
Agency for Toxic Substances and Disease Registry
Division of Toxicology and Human Health Sciences
4770 Buford Highway
Chamblee, GA 30341-3717
Phone: 1-800-CDC-INFO 888-232-6348 (TTY)
Email: Contact CDC-INFO
ATSDR can also tell you the location of occupational and environmental health clinics. These clinics specialize in recognizing, evaluating, and treating illnesses resulting from exposure to hazardous substances.
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