Hydrogen Sulfide

CAS RN: 7783-06-4

Health Effects

    • A) USES: Hydrogen sulfide is a highly toxic, colorless gas. It is denser than air with a rotten egg odor. Hydrogen sulfide is produced naturally by biological degradation of sulfur-containing products (eg, fish, sewage, and manure) and produced as a byproduct in many industrial processes (ie, paper mills, heavy-water production, petroleum refineries, tanneries, mines, carbon disulfide production, and hot asphalt fumes). It can often be found naturally in sulfur hot springs, volcanoes, and underground deposits of natural gas.
    • B) TOXICOLOGY: It interrupts oxidative phosphorylation by inhibition of cytochrome oxidase a3. By inhibiting oxidative phosphorylation, hydrogen sulfide effectively causes cellular asphyxia.
    • C) EPIDEMIOLOGY: Hydrogen sulfide exposure is uncommon; however, with severe exposure manifestations are life-threatening.
      • 1) EXPOSURE: Hydrogen sulfide exposure occurs primarily by inhalation, but can also cause dermal and ocular injury. Suspect hydrogen sulfide toxicity in anyone found unconscious, in a confined space with an odor of rotten eggs present. Darkening of jewelry or silver coins in the vicinity of the victim should also heighten suspicion for hydrogen sulfide exposure.
      • 2) MILD TO MODERATE TOXICITY: In mild to moderate exposures, hydrogen sulfide is primarily an irritant causing upper-airway irritation, conjunctivitis, corneal injury, dermatitis, pharyngitis, pneumonitis, and pulmonary edema (which can be life-threatening). It can also manifest as headache, nausea, vomiting, chest pain, shortness of breath, weakness, dizziness, disequilibrium, keratoconjunctivitis, corneal ulceration and rarely irreversible corneal scarring.
      • 3) SEVERE TOXICITY: Severe exposure manifests as central nervous system depression, seizures, coma, hemoptysis, myocardial ischemia, dysrhythmias, acute lung injury, and death. Central nervous system depression is usually rapid and profound. While recovery may be complete in patients rapidly removed from exposure, permanent sequelae (eg, dementia, memory failure, delirium, ataxia, tremor, muscle rigidity) may result from prolonged hypoxia.
  • A) Spontaneous abortions have occurred after exposure to life-threatening concentrations.
    • A) IARC Carcinogenicity Ratings for CAS7783-06-4 (International Agency for Research on Cancer (IARC), 2016; International Agency for Research on Cancer, 2015; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2010; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2010a; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2008; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2007; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2006; IARC, 2004):
      • 1) Not Listed
    • A) In Rotorua, New Zealand (an active geothermal zone where hydrogen sulfide is released to the atmosphere), cancer deaths were not related to the extent of hydrogen sulfide exposure and there was no overall excess mortality found.
  • A) Hydrogen sulfide exposure was associated with an increased risk of chromosome aberrations in chemical workers. Other factors may be involved in these multiply-exposed cohort populations.
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