Hydrogen Sulfide

H220: Extremely flammable gas [Danger Flammable gases]

H330: Fatal if inhaled [Danger Acute toxicity, inhalation]

H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

P203, P210, P222, P260, P271, P273, P280, P284, P304+P340, P316, P320, P377, P381, P391, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

H220 (100%): Extremely flammable gas [Danger Flammable gases]

H280 (27.1%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H330 (100%): Fatal if inhaled [Danger Acute toxicity, inhalation]

H400 (100%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

P203, P210, P222, P260, P271, P273, P280, P284, P304+P340, P316, P320, P377, P381, P391, P403, P403+P233, P405, P410+P403, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 2542 reports by companies from 28 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

P203, P210, P222, P280, P377, P381, and P403 (click each P-code to see the statement)

H280: Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

P203, P210, P222, P260, P264, P264+P265, P270, P271, P280, P284, P304+P340, P305+P351+P338, P308+P316, P316, P320, P321, P337+P317, P377, P381, P403, P403+P233, P405, P410+P403, and P501 (click each P-code to see the statement)

Administration of oxygen may be needed. Fresh air, rest. Half-upright position. Artificial respiration may be needed. No mouth-to-mouth artificial respiration. Refer immediately for medical attention.

ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Warning: Caution is advised. Vital signs should be monitored closely.

Signs and Symptoms of Acute Hydrogen Sulfide Exposure: Signs and symptoms of acute exposure to hydrogen sulfide may include tachycardia (rapid heart rate) or bradycardia (slow heart rate), hypotension (low blood pressure), cyanosis (blue tint to skin and mucous membrane), cardiac palpitations, and cardiac arrhythmias. Dyspnea (shortness of breath), tachypnea (rapid respiratory rate), bronchitis, pulmonary edema, respiratory depression, and respiratory paralysis may occur. Neurological effects include giddiness, irritability, drowsiness, weakness, confusion, delirium, amnesia, headache, sweating, and dizziness. Muscle cramping, tremor, excessive salivation, cough, convulsions, and coma may be noted. Nausea, vomiting, and diarrhea are commonly seen. Exposure to hydrogen sulfide gas may result in skin irritation, lacrimation (tearing), inability to detect odors, photophobia (heightened sensitivity to light), and blurred vision.

Emergency Life-Support Procedures: Acute exposure to hydrogen sulfide may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:

1. Move victims to fresh air. Emergency personnel should avoid self-exposure to hydrogen sulfide.

2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.

3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

4. RUSH to a health care facility!

Dermal/Eye Exposure:

1. Remove victims from exposure. Emergency personnel should avoid self- exposure to hydrogen sulfide.

3. Remove contaminated clothing as soon as possible.

4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.

5. Wash exposed skin areas for at least 15 minutes with soap and water.

6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

7. RUSH to a health care facility!

Ingestion Exposure: No information is available. (EPA, 1998)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· Removal of solidified molten material from skin requires medical assistance.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

Stop flow of gas. Use water to keep fire-exposed containers cool and to protect men effecting the shut-off. Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and special protective clothing. Evacuate area endangered by gas. Move container from fire area. Stay away from ends of tanks. Withdraw immediately in case of rising sound from venting safety device or any discoloration on tank due to fire. Cool containers with water using unmanned device until well after the fire is out. Isolate for one-half mile in all directions if tank car or truck is involved in fire.

A very flammable gas. For small fires let burn unless leak can be stopped immediately. For large fires, use water spray, fog or foam. (EPA, 1998)

Shut off supply; if not possible and no risk to surroundings, let the fire burn itself out. In other cases extinguish with water spray, dry powder. In case of fire: keep cylinder cool by spraying with water.

Stop flow of gas before extinguishing fire. Use water spray, dry chemical, or carbon dioxide. Use water sprat to keep fire-exposed containers cool.

STOP FLOW OF GAS. USE WATER TO KEEP FIRE EXPOSED CONTAINERS COOL & TO PROTECT MEN EFFECTING SHUT OFF.

If material is on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Apply water from as far a distance as possible. Cool all affected containers with flooding quantities of water. Use water spray to knock-down vapors.

To fight fire, stop flow of gas.

HEAVIER THAN AIR ... & MAY TRAVEL CONSIDERABLE DISTANCE TO SOURCE OF IGNITION & FLASHBACK.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· Do not touch or walk through spilled material.

Small Dry Spill

· With clean shovel, place material into clean, dry container and cover loosely; move containers from spill area.

Large Spill

· Wet down with water and dike for later disposal.

· Prevent entry into waterways, sewers, basements or confined areas.

· Ventilate closed spaces before entering, but only if properly trained and equipped.

· All equipment used when handling the product must be grounded.

· Stop leak if you can do it without risk.

· A vapor-suppressing foam may be used to reduce vapors.

Small Spill

· Absorb with earth, sand or other non-combustible material and transfer to containers for later disposal.

· Use clean, non-sparking tools to collect absorbed material.

· Dike far ahead of liquid spill for later disposal.

· Water spray may reduce vapor, but may not prevent ignition in closed spaces.

· Many gases are heavier than air and will spread along the ground and collect in low or confined areas (sewers, basements, tanks, etc.).

· Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material.

· Do not direct water at spill or source of leak.

· If possible, turn leaking containers so that gas escapes rather than liquid.

· Isolate area until gas has dispersed.

· Consider igniting spill or leak to eliminate toxic gas concerns.

· Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers.

Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1053 datasheet.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. (ERG, 2024)

Immediate precautionary measure

· Isolate spill or leak area for at least 25 meters (75 feet) in all directions.

· Consider initial downwind evacuation for at least 100 meters (330 feet).

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.

· Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

· For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.

· For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary.

· Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

· See Table 1 - Initial Isolation and Protective Action Distances.

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.

Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Isolate area until gas has dispersed. Consider igniting spill or leak to eliminate toxic gas concerns. (ERG, 2024)

Fireproof. Separated from strong oxidants. Cool. Keep in a well-ventilated room. Install continous monitoring system with alarm. Provision to contain effluent from fire extinguishing. Store in an area without drain or sewer access.

Store in a cool, dry, well-ventilated location. Separate from oxidizable materials.

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

· Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE.

TIH (Toxic Inhalation Hazard) - Term used to describe gases and volatile liquids that are toxic when inhaled. Some are TIH materials themselves, e.g., chlorine, and some release TIH gases when spilled in water, e.g., chlorosilanes. [ERG 2016].

5.0 [ppm]

AEGL 1: Notable discomfort, irritation, or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure (Unit: ppm)

AEGL 2: Irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape (Unit: ppm)

AEGL 3: Life-threatening health effects or death (Unit: ppm)

* Level of Odor Awareness = 0.01 ppm

AEGLs Status: Final

0.51 [ppm]

27 [ppm]

50 [ppm]

10 ppm (15 mg/m³) [10 min]

C 10 ppm (15 mg/m3) [10-minute]

20 ppm (C), 50 ppm (Peak) [10 min, once only, if no other measurable exposure occurs]

C 20 ppm 50 ppm [10-minute maximum peak] See Appendix G

100 ppm (NIOSH, 2024)

100.0 [ppm]

Excerpts from Documentation for IDLHs: It has been reported that 170 to 300 ppm is the maximum concentration that can be endured for 1 hour without serious consequences [Henderson and Haggard 1943] and that olfactory fatigue occurs at 100 ppm [Poda 1966]. It has also been reported that 50 to 100 ppm causes mild conjunctivitis and respiratory irritation after 1 hour; 500 to 700 ppm may be dangerous in 0.5 to 1 hour; 700 to 1,000 ppm results in rapid unconsciousness, cessation of respiration, and death; and 1,000 to 2,000 ppm results in unconsciousness, cessation of respiration, and death in a few minutes [Yant 1930].

See: 7783064

1.0 [ppm]

8 hr Time Weighted Avg (TWA): 1 ppm; 15 min Short Term Exposure Limit (STEL): 5 ppm.

1 ppm as TWA; 5 ppm as STEL.

1 ppm [2009]

5 ppm [2009]

7.1 mg/m

Small Fire

· Dry chemical, CO2, sand, earth, water spray or regular foam.

Large Fire

· Water spray, fog or regular foam.

· If it can be done safely, move undamaged containers away from the area around the fire.

Fire Involving Metal Pigments or Pastes (e.g. "Aluminum Paste")

· Aluminum Paste fires should be treated as a combustible metal fire. Use DRY sand, graphite powder, dry sodium chloride-based extinguishers or class D extinguishers. Also, see GUIDE 170.

Fire Involving Tanks, Rail Tank Cars or Highway Tanks

· Cool containers with flooding quantities of water until well after fire is out.

· For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient.

Hydrogen sulfide appears as a colorless gas having a strong odor of rotten eggs. Boiling point -60.2 °C. Shipped as a liquid confined under its own vapor pressure. Density (liquid) 8.3 lb / gal. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Gas is very toxic by inhalation. Fatigues the sense of smell which cannot be counted on to warn of the continued presence of the gas. Prolonged exposure of closed containers to heat may result in their violent rupturing and rocketing. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 0.1 ppm Source/use/other hazard: Disinfectant lubricant/oils; interm for HC manufacture; deadens sense of smell.

Colorless gas with a strong odor of rotten eggs; Note: Sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presence of H2S; Shipped as a liquefied compressed gas; [NIOSH]

COLOURLESS COMPRESSED LIQUEFIED GAS WITH CHARACTERISTIC ODOUR OF ROTTEN EGGS.

Flammable, poisonous, colorless gas with a strong odor of rotten eggs.

Colorless gas with a strong odor of rotten eggs. [Note: Sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presence of H2S. Shipped as a liquefied compressed gas.]

Colorless gas [Shipped as a liquefied compressed gas].

Strong odor of rotten eggs [Note: Sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presense of hydrogen sulfide].

Offensive odor

Sweetish taste

-76.59 °F at 760 mmHg (EPA, 1998)

-60.33 °C

-76.59 °F

-59.55 °C @760 [mm Hg]

-121.9 °F (EPA, 1998)

-85.49 °C

-121.88 °F

-85.5 °C

Flammable gas

NA (Gas)

0.4 % (NIOSH, 2024)

1 g dissolves in 94.3 ml absolute alcohol at 20 °C; 1 g dissolves in 48.5 mL ether at 20 °C

In water, 3980 mg/L at 20 °C

Soluble in glycerol, gasoline, kerosene, carbon disulfide, crude oil.

Soluble in certain polar organic solvents, notably methanol, acetone, propylene carbonate, sulfolane, tributyl phosphate, various glycols, and glycol ethers. N-Methylpyrrolidine dissolves 49 ml/g at 20 °C at atmospheric pressure.

3.74 mg/mL at 21 °C

Solubility in water, g/100ml at 20 °C: 0.5

0.916 at -76 °F (EPA, 1998) - Less dense than water; will float

1.5392 g/L at 0 °C at 760 mm Hg; Gas: 1.19 (Air = 1.00)

Relative density (water = 1): 0.92

0.916@76 °F

1.393 @25 °C

1.19(relative gas density)

1.19 (EPA, 1998) - Heavier than air; will sink (Relative to Air)

1.189 (Air = 1)

Relative vapor density (air = 1): 1.19

15200 mmHg at 77.9 °F (EPA, 1998)

Vapor pressure = 1.56X10+4 mm Hg at 25 °C /from experimentally-derived coefficients

1.36X10+4 mm Hg at 20 °C

Vapor pressure, kPa at 20 °C: 1880

17.6 atm

Highly flammable; a flame can very easily flash back to the source of leak.

Sulfides, Inorganic

Highly Flammable

HYDROGEN SULFIDE reacts as an acid and as a reducing agent. Explodes on contact with oxygen difluoride, bromine pentafluoride, chlorine trifluoride, dichlorine oxide, silver fulminate. May ignite and explode when exposed to powdered copper in oxygen [Mertz, V. et al., Ber., 1880, 13, p. 722]. May react similarly with other powdered metals. Ignites on contact with metal oxides and peroxides (barium peroxide, chromium trioxide, copper oxide, lead dioxide, manganese dioxide, nickel oxide, silver oxide, silver dioxide, thallium trioxide, sodium peroxide, mercury oxide, calcium oxide) [Mellor, 1947, vol. 10, p. 129, 141]. Ignites with silver bromate, lead(II) hypochlorite, copper chromate, nitric acid, lead(IV) oxide and rust. May ignite if passed through rusty iron pipes [Mee, A. J., School Sci. Rev., 1940, 22(85), p. 95]. Reacts exothermically with bases. The heat of the reaction with soda lime, sodium hydroxide, potassium hydroxide, barium hydroxide may lead to ignition or explosion of the unreacted portion in the presence of air / oxygen [Mellor, 1947, vol. 10, p. 140].

Fuming nitric acid reacts with incandescence with hydrogen sulfide.

Forms explosive reactions with bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride and phenyl diazonium chloride.

Addition of powdered copper to 1:2 mixture of hydrogen sulfide and oxygen causes the metal to become incandescent and ignite the explosive mixture.

A mixture of /hydrogen sulfide/ with air passed over copper powder may attain red heat. Finely divided tungsten glows red hot in a stream of hydrogen sulfide.

For more Hazardous Reactivities and Incompatibilities (Complete) data for HYDROGEN SULFIDE (9 total), please visit the HSDB record page.

Strong oxidizers, strong nitric acid, metals

CDC-ATSDR Toxicological Profile

Although very pungent at first, hydrogen sulfide quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. Hydrogen sulfide forms a complex bond with iron in the mitochondrial cytochrome enzymes, thereby blocking oxygen from binding and stopping cellular respiration. (L1139)

Hydrogen sulfide

Respiratory

2 x 10 ^-3 mg/m^3

There are no published reports of carcinogenesis, mutagenesis, or teratogenesis attributable to hydrogen sulfide exposure.

No indication of carcinogenicity to humans (not listed by IARC).

Hydrogen sulfide is a highly toxic and flammable gas. 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 hydrogen sulfide is comparable with that of hydrogen cyanide. (L1139)

The substance can be absorbed into the body by inhalation.

inhalation, skin and/or eye contact

Oral; inhalation; dermal

Cough. Headache. Dizziness. Nausea. Laboured breathing. Shortness of breath. Irregular heartbeat. Convulsions. Unconsciousness.

ON CONTACT WITH LIQUID: FROSTBITE.

Redness. Pain.

irritation eyes, respiratory system; apnea, coma, convulsions; conjunctivitis, eye pain, lacrimation (discharge of tears), photophobia (abnormal visual intolerance to light), corneal vesiculation; dizziness, headache, lassitude (weakness, exhaustion), irritability, insomnia; gastrointestinal disturbance; liquid: frostbite

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. Higher concentrations of 700-800 ppm tend to be fatal. (L1139)

Neurological (Nervous System), Respiratory (From the Nose to the Lungs)

Eyes, respiratory system, central nervous system

Other Poison - Chemical Asphyxiant

Toxic Pneumonitis - Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

Fibrogenic - Inducing tissue injury and fibrosis (scarring).

ATSDR Final

IRIS Current

HEAST Current

LC50 (mice) = 634 ppm/1H

Man: severe toxic effects 200 ppm = 280 mg/cu m 1 min; symptoms of illness 50 ppm = 70 mg/cu m; unsatisfactory: 20 ppm = 28 mg/cu m

Man: lethal: 600 ppm/30 min; 800 ppm, immediate /lethality/

Lethal blood concentration: 0.092 mg %.

LC50 Rhesus monkey inhalation 700 mg/cu m/35 min.

LC50 Mouse inhalation 1500 mg/cu m/18 min

LC50 Mouse inhalation 380 mg/cu m/410 min

LC50 Mouse inhalation 96 mg/cu m/804 min

For more Non-Human Toxicity Values (Complete) data for HYDROGEN SULFIDE (9 total), please visit the HSDB record page.

Treatment involves immediate inhalation of amyl nitrite, injections of sodium nitrite, inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm, and in some cases hyperbaric oxygen therapy (HBO). HBO therapy has anecdotal support and remains controversial. (L1139)

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase (NOS) inhibitor, is profoundly protective against 1-methy-4-phenylpyridinium ion (MPP+)-induced neurotoxicity. Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of MPP+; while hydrogen sulfide (H2S) is a pivotal endogenous antioxidant. This study is to assess the potential role of endogenous H2Sin the neuroprotection of ADMA against MPP+ induced toxicity in PC12 cells. We showed that ADMA prevented MPP+-induced inhibition of endogenous H2Sgeneration through inhibiting the down-regulation of cystathionine-beta-synthetase (CBS, the major enzyme responsible for endogenous H?S generation in PC12 cells) expression and activity elicited by MPP+. ADMA obviously attenuated MPP+-triggered accumulation of intracellular ROS, dissipation of mitochondrial membrane potential (MMP), release of cytochrome c (Cyt-c), and down regulation of Bcl-2 protein expression in PC12 cells. Inhibition of CBS activity by amino-oxyacetate and CBS silencing with a short hairpin RNA vector targeting rat CBS gene reversed the protective action of ADMA against MPP+ caused cytotoxicity, ROS overproduction, and MMP loss in PC12 cells. These results indicate that the protection of ADMA against MPP+ mediated neurotoxicity involves the melioration of MPP+ induced inhibition of endogenous H2S generation. Our findings suggest that modulation of H2S production provide new therapeutic targets for the treatment of neurodegenerative disease, such as Parkinson's disease.

Pregnant rats were exposed to 0, 100, 200, 400 or 800 ppm of carbon disulfide (CS2), 100 ppm hydrogen sulfide (H2S) alone or in combination with 400 or 800 ppm CS2, 6 hr/day during days 6-20 gestation. Maternal reproduction and fetal parameters were evaluated on gestational day 21. Treatment with 100 or 200 ppm CS2 or with 100 ppm H2S caused no maternal toxicity or adverse effects on the developing embryo or fetus. Exposure to 400 or 800 ppm CS2 resulted in a low incidence of club foot and in a significant reduction of maternal weight gain. Significant incr in unossified sternebrae occurred at 800 ppm CS2 and reduction of fetal body weight at 400 and 800 ppm CS2. The latter effect was enhanced by combination with 100 ppm H2S. ... At levels of exposure associated with maternal toxicity, CS2 leads to an incr in incidence of club foot and to fetal toxicity which is enhanced by simultaneous exposure to H2S.

Hydrogen sulfide ... is produced endogenously in mammalian tissues from L-cysteine mainly by two pyridoxal-5'-phosphate dependent enzymes, cystathionine beta-synthetase and cystathionine gamma-lyase. ... Cystathionine beta-synthetase in the brain produces H2S, and that H2S facilitates the induction of hippocampal long term potentiation by enhancing NMDA receptor activity. ... mRNA for another H2S producing enzyme, cystathionine gamma-lyase is expressed in the ileum, portal vein and thoracic aorta. The ileum also expresses cystathionine beta-synthetase mRNA. These tissues produce H2S, and this production is blocked by cystathionine beta-synthetase and cystathionine gamma-lyase specific inhibitors. Although exogenously applied H2S alone relaxed these smooth muscles, much lower concn of H2S greatly enhanced the smooth muscle relaxation induced by NO in the thoracic aorta. These observations suggest that the endogenous H2S may regulate smooth muscle tone in synergy with NO.

NITRITE AS AN ANTIDOTE FOR ACUTE HYDROGEN SULFIDE INTOXICATION CAN ONLY BE EFFECTIVE WITHIN THE FIRST FEW MINUTES AFTER THE EXPOSURE, AT WHICH TIME RESUSCITATION AND/OR VENTILATION OF THE VICTIM ARE LIKELY TO PRODUCE CONDITIONS IN WHICH THE NITRITE ACTUALLY SLOWS SULFIDE REMOVAL /SRP: DUE TO DECR BINDING OF THE SULFIDE TO METHEMOGLOBIN/.

Immediately remove person from exposure and ensure that the airway is clear. Given 100% oxygen by tight-fitting oronasal mask or endotracheal tube. Hyperbaric oxygen at 3 atm has been successful.

A CASE REPORT OF A 34-YEAR-OLD MALE RENDERED UNCONSCIOUS BY EXPOSURE TO A HIGH CONCENTRATION OF HYDROGEN SULFIDE FUMES IS PRESENTED TO ILLUSTRATE THE ADVANTAGES OF OXYGEN THERAPY. SIGNIFICANT IMPROVEMENT IN BLOOD GASES WAS ACHIEVED WITHIN 1 HOUR OF STARTING OXYGEN. THE RISKS OF NITRITE THERAPY ARE DISCUSSED.

EC50; Species: Gammarus pseudolimnaeus (Scud) length 11 mm; Conditions: freshwater, flow through, 15 °C, pH 7.5, hardness 220 mg/L CaCO3, alkalinity 140 mg/L CaCO3, dissolved oxygen 4 mg/L; Concentration: 62 ug/L for 48 hr; Effect: intoxication, immobilization

EC50; Species: Gammarus pseudolimnaeus (Scud) length 11 mm; Conditions: freshwater, flow through, 15 °C, pH 7.5, hardness 220 mg/L CaCO3, alkalinity 140 mg/L CaCO3, dissolved oxygen 6 mg/L; Concentration: 71 ug/L for 48 hr; Effect: intoxication, immobilization

EC50; Species: Gammarus pseudolimnaeus (Scud) length 11 mm; Conditions: freshwater, flow through, 10 °C, pH 7.5, hardness 220 mg/L CaCO3, alkalinity 140 mg/L CaCO3, dissolved oxygen 6 mg/L; Concentration: 95 ug/L for 48 hr; Effect: intoxication, immobilization

EC50; Species: Gammarus pseudolimnaeus (Scud) length 11 mm; Conditions: freshwater, flow through, 15 °C, pH 7.5, hardness 220 mg/L CaCO3, alkalinity 140 mg/L CaCO3, dissolved oxygen 4 mg/L; Concentration: 42 ug/L for 10 days; Effect: intoxication, immobilization

For more Ecotoxicity Values (Complete) data for HYDROGEN SULFIDE (35 total), please visit the HSDB record page.

/AQUATIC SPECIES/ Exposure of channel catfish to 0.5 mg/L hydrogen sulfide at 20 °C resulted in hyperpnea, followed by apnea and respiratory arrest.

/AQUATIC SPECIES/ The effects of hydrogen sulfide (H2S) were tested in three ecotoxicological tests in order to evaluate its confounding potential in assessment of pore water and groundwater toxicity. The luminescent bacteria Vibrio fischeri, the water flea Daphnia magna, and the microalgae Scenedesmus vacuolatus often are part of a biotest battery. A new technique for the synthesis of hydrogen sulfide solutions of defined concentrations using an electrochemical generator instead of sodium sulfide solutions was used. Because hydrogen sulfide is volatile, the loss rate of H2S was studied over time to enable estimation of the mean test concentrations over the whole test duration. Loss rates were calculated to be 13 + or - 6% after 30 min, and 39 + or - 11% and 43 + or - 16% after a 24- and 48-hr exposure time, respectively. Sensitivities of the test organisms in terms of median effective concentration (EC50), corrected for the above loss rates, varied from 0.28 to 0.0036 and 0.055 mM for the luminescent bacteria, the crustacea, and the algae, respectively. A species-sensitivity distribution using EC and mean lethal concentration literature data for marine and freshwater crustaceans and phytoplankton showed a medium sensitivity of the water flea D. magna, though the bacteria V. fischeri and the algae S. vacuolatus were among the least-sensitive group of organisms. This demonstrates that only the algae and the bacteria are easy to use in the assessment of toxicity of matrices with H2S concentrations above 0.06 mM.

/PLANTS/ /Ten species of weeds 3 to 6 weeks of age were/ fumigated with 100 to 500 ppm hydrogen sulfide for four hours. /Results suggested that/ differences in susceptibility to injury /existed/ and ... that younger plants were more sensitive to damage than older ones. /Data also suggested/ that increases in temperature exacerbated the damage, as did dry soil.

2.80e+06

1.20e+07

2.10e+00

8.80e+00

4.20e+00

5.00e+01

2.00e-03

Volatile

8.50e+06

3.60e+07

6.30e+00

2.60e+01

1.30e+01

The substance is very toxic to aquatic organisms.

Hydrogen sulfide's production and use in the synthesis of sulfur compounds, the manufacture of heavy water and in metallurgy may result in its release to the environment through various waste streams. Hydrogen sulfide emissions are associated with municipal sewers and sewage treatment plants, swine containment and manure-handling operations, pulp and paper operations and industrial sources such as petroleum refineries, natural gas plants, petrochemical plants, coke oven plants, food processing plants, and tanneries. Hydrogen sulfide occurs in the gases from volcanoes, sulfur springs, undersea vents, swamps, and stagnant bodies of water and in crude petroleum and natural gas. If released to air, hydrogen sulfide will exist as a gas. Gas-phase hydrogen sulfide will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 3.3 days. The reaction of hydrogen sulfide with hydroxyl radicals in air yields H20 and the SH radical which is further oxidized to SO, then sulfur dioxide, and ultimately sulfate compounds. Gas-phase reactions with ozone and nitrate radicals are relatively slow and not competitive with hydroxyl radicals. Hydrogen sulfide does not absorb solar radiation reaching the troposphere and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to soil, hydrogen sulfide gas can partition to soil through adsorption. Volatilization of hydrogen sulfide from moist soil surfaces is expected to be an important fate process given a Henry's Law constant of 0.0098 atm-cu m/mole at 25 °C. Since hydrogen sulfide is a gas at ambient temperatures, it is expected to volatilize from dry soil surfaces; however, hydrogen sulfide gas can adsorb to both moist and dry soil surfaces which may attenuate the rate of volatilization. Hydrogen sulfide can be consumed by bacteria found in soil and water that oxidize hydrogen sulfide to elemental sulfur. If released to water, volatilization from water surfaces is expected to be an important fate process based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 1.8 hours and 2.3 days, respectively. Hydrogen sulfide is a weak base and has two pKa values of pKa1 = 7.04 and pKa2 = 11.96 which indicate some dissociation at environmental pHs. At pH 5-6, the water-air transfer rate was found to behave like an unreactive gas, but as the pH increases to pH10, the transfer rate was enhanced and nearly 200 times faster at pH10 than pH 5. At 25 °C, the half-life for the rate of oxidation of hydrogen sulfide in air-saturated natural waters is about 50 hours in natural water and 26 hours in seawater (pH8). Hydrogen sulfide does not have bioaccumulation or food chain contamination potential. Occupational exposure to hydrogen sulfide occurs through inhalation at workplaces where hydrogen is produced or used. Exposure of the general population to hydrogen sulfide most likely occurs through inhalation of ambient air, especially in the vicinity of industries that emit hydrogen sulfide. Hydrogen sulfide is one of the principal components in the sulfur cycle in nature, so the general population will have some exposure to hydrogen sulfide from this source. Hydrogen sulfide is also produced in the human large intestine and by the natural bacteria found in the human mouth. (SRC)

In sulfur springs, volcanic gas, natural gas, and a component of crude petroleum.

HIGH LEVELS OF HYDROGEN SULFIDE IN A FLORIDA WELL WATER SOURCE WERE APPARENTLY RESPONSIBLE FOR ATTACKING /CORRODING/ A/C PIPE.

... GAS /PRODUCED/ FROM DECOMP MANURE ... /&/ LEAKING /SEWER/ MANHOLE COVER.

Hydrogen sulfide occurs in the gases from volcanoes, sulfur springs, undersea vents, swamps, and stagnant bodies of water and in crude petroleum and natural gas. Bacteria found in the human mouth and gastrointestinal tract produce hydrogen sulfide during the digestion of food containing vegetable or animal proteins(1).

Hydrogen sulfide's production and use in the synthesis of sulfur compounds, the manufacture of heavy water and in metallurgy(1) may result in its release to the environment through various waste streams(SRC). Hydrogen sulfide emissions are associated with municipal sewers and sewage treatment plants, swine containment and manure-handling operations, and pulp and paper operations(2); industrial sources of hydrogen sulfide include petroleum refineries, natural gas plants, petrochemical plants, coke oven plants, food processing plants, and tanneries(2).

... POLLUTANT IN ATMOSPHERE IN /VICINITY/ OF INDUSTRIAL PAPER PLANTS USING KRAFT PROCESS.

In cigarette smoke: 40 ppm; combustion of coal: 0.0045 lb/lb coal; combustion of fuel oil: 1 lb/1,000 lb gas; combustion of natural gas: 0.13 lb/1,000 lb gas; In municipal sewer air: 0.2-10 ppm.

THERMAL DEGRADATION OF POLYPHENYLENE SULFIDE MAY YIELD HYDROGEN SULFIDE ... .

For more Artificial Pollution Sources (Complete) data for HYDROGEN SULFIDE (6 total), please visit the HSDB record page.

TERRESTRIAL FATE: Hydrogen sulfide gas has been observed to partition to soils(1). For example, when hydrogen sulfide gas was passed over six air-dried and moist (50% field capacity) soils, 15.4-65.2 mg/g and 11.0-65.2 mg/g of hydrogen sulfide rapidly adsorbed to the dry and moist soils, respectively(1). Neither the capacity or rate of sorption was correlated to soil pH, organic matter content, or clay content; sterile controls ruled out the involvement of microorganisms(1); it was suggested that adsorption to soil surfaces might be an environmental sink for gaseous hydrogen sulfide(1). Volatilization of hydrogen sulfide from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 0.0098 atm-cu m/mole at 25 °C(2). Hydrogen sulfide is a gas at ambient temperatures(3) and expected to volatilize from dry soil surfaces(SRC); however, hydrogen sulfide gas can adsorb to both moist and dry soil surfaces(1) which may attenuate the rate of volatilization(SRC). Hydrogen sulfide can be consumed by bacteria found in soil and water that oxidize hydrogen sulfide to elemental sulfur(4).

AQUATIC FATE: Volatilization of hydrogen sulfide from water surfaces is expected(1) based upon a Henry's Law constant of 0.0098 atm-cu m/mole at 25 °C(2). Using this Henry's Law constant and an estimation method(1), volatilization half-lives for a model river and model lake are 1.8 hours and 2.3 days, respectively(SRC). Hydrogen sulfide is a weak base and has two pKa values of pKa1 = 7.04 and pKa2 = 11.96(3) which indicate some dissociation at environmental pHs(4). At pH 5-6, the water-air transfer rate was found to behave like an unreactive gas, but as the pH increases to pH10, the transfer rate was enhanced and nearly 200 times faster at pH10 than pH 5(4). The rate of oxidation of hydrogen sulfide in air-saturated natural waters was measured over a temperature range (5-65 °C), pH range (1-12) and ionic strength(5); at 25 °C, the half-life was about 50 hours in water and 26 hours in seawater (pH8)(5). Hydrogen sulfide does not have bioaccumulation or food chain contamination potential(6). Hydrogen sulfide can be consumed by bacteria found in soil and water that oxidize hydrogen sulfide to elemental sulfur(7).

ATMOSPHERIC FATE: At atmospheric pressures, hydrogen sulfide is a gas above its boiling point of -60.33 °C(1), and therefore, will exist as a gas in the ambient environment(SRC). Gas-phase hydrogen sulfide is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 3.3. days(SRC), calculated from its rate constant of 4.8X10-12 cu cm/molecule-sec at 25 °C(2). The reaction of hydrogen sulfide with hydroxyl radicals in air yields H20 and the SH radical(2) which is further oxidized to SO, then sulfur dioxide, and ultimately sulfate compounds(3). The gas-phase reaction of hydrogen sulfide with nitrate radicals in night-time air is relative slow and not competitive with hydroxyl radicals(4); the rate constant for reaction with nitrate radicals is reported as <8X10-16 cu cm/molecule-sec at 25 °C(5). Vapor-phase reaction with ozone is also relatively slow(SRC) based on a rate constant <2X10-20 cu cm/molecule-sec at 25 °C(5). Hydrogen sulfide does not absorb solar radiation reaching the troposphere(6) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

Atmospheric Fate: The lifetime of hydrogen sulfide (H2S) is affected by ambient temperature and other atmospheric variables including humidity, sunshine, and presence of other pollutants. The decreased temperatures and decreased levels of hydroxide in northern regions (e.g. Alberta, Canada) in winter increase the residence time of H2S in air.

Once released into the atmosphere, hydrogen sulfide will behave like many other gaseous pollutants and be dispersed and eventually removed. Residence times in the atmosphere range from about one day to more than 40 days, depending upon season, latitude, and atmospheric conditions.

Microorganisms in soil and water are involved in oxidation-reduction reactions which oxidize hydrogen sulfide to elemental sulfur. Members of the genera Beggiatoa, Thioploca, and Thiotrix function in transition zones between aerobic and anaerobic conditions where both molecular oxygen and hydrogen sulfide are found. /Also/ some photosynthetic bacteria oxidize hydrogen sulfide to elemental sulfur. Members of the families Chlorobiaceae and Chromatiaceae (purple sulfur bacteria) are obligate aerobes and are phototropic, and are found in waters with high H2S concentrations. The interactions of these organisms form part of the global sulfur cycle.

The rate constant for the gas-phase reaction of hydrogen sulfide with photochemically-produced hydroxyl radicals has been experimentally determined to be 4.8X10-12 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 3.3 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(2). The reaction of hydrogen sulfide with hydroxyl radicals in air yields H20 and the SH radical(1) which is further oxidized to SO and then sulfur dioxide. The gas-phase reaction of hydrogen sulfide with nitrate radicals in night-time air is relative slow and not competitive with hydroxyl radicals(3); the rate constant for reaction with nitrate radicals is reported as <8X10-16 cu cm/molecule-sec at 25 °C(4). The gas-phase reaction of hydrogen sulfide with ozone is also relatively slow(SRC) based on a rate constant <2X10-20 cu cm/molecule-sec at 25 °C(4). The rate of oxidation of hydrogen sulfide in air-saturated natural waters was measured over a temperature range (5-65 °C), pH range (1-12) and ionic strength(5); at 25 °C, the half-life was about 50 hours in water and 26 hours in seawater (pH8)(5).

Does not have bioaccumulation or food chain contamination potential.

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number U135, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

A potential candidate for rotary kiln incineration at a temperature range of 820 to 1,600 °C and residence times of seconds for liquids and gases, and hours for solids.

A potential candidate for fluidized bed incineration at a temperature range of 450 to 980 °C and residence times of seconds for liquids and gases, and longer for solids.

If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY. /Hydrogen sulfide/

Table: Table of Initial Isolation and Protective Action Distances for Hydrogen sulfide [Table#1661]

/GUIDE 117: GASES - TOXIC - FLAMMABLE (EXTREME HAZARD)/ Fire or Explosion: These materials are extremely flammable. May form explosive mixtures with air. May be ignited by heat, sparks or flames. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Runoff may create fire or explosion hazard. Cylinders exposed to fire may vent and release toxic and flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.

/GUIDE 117: GASES - TOXIC - FLAMMABLE (EXTREME HAZARD)/ Health: TOXIC; Extremely Hazardous. May be fatal if inhaled or absorbed through skin. Initial odor may be irritating or foul and may deaden your sense of smell. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.

/GUIDE 117: GASES - TOXIC - FLAMMABLE (EXTREME HAZARD)/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Many gases are heavier than air and will spread along ground and collect in low or confined areas (sewers, basements, tanks). Keep out of low areas. Ventilate closed spaces before entering.

For more DOT Emergency Guidelines (Complete) data for HYDROGEN SULFIDE (9 total), please visit the HSDB record page.

UN 1053; Hydrogen sulfide

IMO 2.3; Hydrogen sulfide

49 054 10; Hydrogen sulfide

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Poison Gas Flammable Gas

Symbol: F+, T+, N; R: 12-26-50; S: (1/2)-9-16-36-38-45-61

UN Hazard Class: 2.3; UN Subsidiary Risks: 2.1