Hydrogen sulfide is a colour less, flammable, poisonous gas that smells like rotten eggs.
Hydrogen Sulfide gas is very dangerous and in high concentrations is lethal and in low concentration gives a rotten eggs mell.
Hydrogen sulfide(or hydrogen sulphide) is the chemical compound with theformulaH2S. This colorless, toxic, flammable gas is partially responsible for the foul odor of rotten eggs and flatulence. It often results from the bacterial break down of sulfur-containing organic matter in the absence of oxygen, such as in swamp sand sewers (anaerobic digestion). It also occurs in volcanic gases,natural gas and some well waters. The body produces small amounts of H2S and uses it as a signaling molecule.
Hydrogen Sulfide gas is very dangerous and in high concentrations is lethal and in low concentration gives a rotten eggs mell.
Hydrogen sulfide(or hydrogen sulphide) is the chemical compound with theformulaH2S. This colorless, toxic, flammable gas is partially responsible for the foul odor of rotten eggs and flatulence. It often results from the bacterial break down of sulfur-containing organic matter in the absence of oxygen, such as in swamp sand sewers (anaerobic digestion). It also occurs in volcanic gases,natural gas and some well waters. The body produces small amounts of H2S and uses it as a signaling molecule.
Safety
Hydrogen sulfide is a highly toxic and flammable gas. Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. For safe handling procedures, a hydrogen sulfide material safety data sheet (MSDS)should be consulted.
At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm.
Exposure to lower concentrations can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs. These symptoms usually go away in a few weeks. Long-term, low-level exposure may result in fatigue, loss of appetite,headaches, irritability, poor memory, and dizziness. Chronic exposures to low level H2S (around 2ppm) has been implicated in increased miscarriage and reproductive health issues amongst Russian and Finnish wood pulp workers, but the reports have not (as of circa 1995) been replicated.
Toxicity of H2S
Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H2S is comparable with that of hydrogen cyanide. It forms a complex bond with iron in the mitochondrialcy to chromeenzymes, thereby blocking oxygen from binding and stop ping cellular respiration. Since hydrogen sulfide occurs naturally in the environment and the gut, enzymes exist in the body capable of detoxifying it by oxidation to (harmless) sulfate.Hence, low levels of sulfide may be tolerated indefinitely.At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm.
Exposure to lower concentrations can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs. These symptoms usually go away in a few weeks. Long-term, low-level exposure may result in fatigue, loss of appetite,headaches, irritability, poor memory, and dizziness. Chronic exposures to low level H2S (around 2ppm) has been implicated in increased miscarriage and reproductive health issues amongst Russian and Finnish wood pulp workers, but the reports have not (as of circa 1995) been replicated.
Toxicity of H2S in Details
0.0047ppmis the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide, normally described as resembling "a rotten egg".
Less than 10 ppm has an exposure limit of 8 hours per day.
10–20 ppm is the borderline concentration for eye irritation.
50–100 ppm leads to eye damage.
At 150–250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger,
320–530 ppm leads to pulmonary edema with the possibility of death.
530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
Hydrogen sulfide was used by the British as a chemical agent during World War One. It was not considered to be an ideal war gas, but while other gases were in short supply it was used on two occasions in 1916.The gas, produced by mixing certain household ingredients, was used in a suicide wave in 2008, primarily in Japan.
Less than 10 ppm has an exposure limit of 8 hours per day.
10–20 ppm is the borderline concentration for eye irritation.
50–100 ppm leads to eye damage.
At 150–250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger,
320–530 ppm leads to pulmonary edema with the possibility of death.
530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
Hydrogen sulfide was used by the British as a chemical agent during World War One. It was not considered to be an ideal war gas, but while other gases were in short supply it was used on two occasions in 1916.The gas, produced by mixing certain household ingredients, was used in a suicide wave in 2008, primarily in Japan.
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