Hydrogen Sulfide Treatment

Hydrogen sulfide is a molecular compound with the formula H2S. It's a gas at room temperature with a foul odor that's obvious even at extremely low concentrations; humans detect the scent at levels as low as just one or two parts per billion (ppb). Levels over 50 ppm can cause eye damage; levels over 100 ppm are extremely dangerous, and at high concentrations a few breaths may be fatal. It's vital to ensure victims of H2S poisoning receive rapid treatment.

General Precautions

• In past incidents, rescuers attempting to remove a victim from an area of high concentration have occasionally been killed themselves. It's important to take proper precautions before trying to rescue a victim of H2S poisoning. Although H2S is a dangerous eye irritant, it's not absorbed quickly through the skin, so skin protection is typically not necessary. Respiratory protection, however, is absolutely essential.

Signs of Acute Exposure

• Acute exposure to high levels of H2S causes dizziness and irregular heartbeat rapidly followed by unconsciousness, coma and possibly by death. Conjunctivitis and a blurred or cloudy eye surface are possible symptoms as well. Bronchitis and buildup of fluid in the lungs are sometimes immediate but can take place as much as 72 hours afterward. The lingering "rotten egg" odor is another telltale sign. H2S is corrosive to copper in sufficient concentrations, so if the patient has discolored copper coins in their pockets, it's another indication they may have been exposed to hydrogen sulfide.

Treatment for Acute Exposure

• The first and most important step is to take the victim from the area of high concentration as quickly as possible. Remove contaminated clothing (if the patient was exposed to more moderate levels and is still conscious, they may be able to do so themselves). Flush the patient's eyes with water if they are irritated or inflamed. If the patient's condition warrants it, it may in some cases be necessary to place a breathing tube or carry out other advanced life support procedures. Administering high-flow oxygen may help the patient to recover. Another useful approach is intravenous administration of sodium nitrite. The sodium nitrite will oxidize hemoglobin in the blood to methemoglobin, which can bind the hydrogen sulfide. This technique is quite similar to treatment for cyanide poisoning since both hydrogen cyanide and hydrogen sulfide disrupt the same process in the cell in a similar way. Since serious exposure can damage the brain or heart, follow-up treatment may be necessary to manage any complications.

Chronic Exposure

• Unlike the acute exposure cases described above, chronic exposure is less life-threatening and may require treatment. Continuous exposure to low levels over a long period of time can cause headaches, bronchitis, weakness and chronic eye irritation. The best treatment in cases of chronic exposure is to avoid further exposure to the gas; it doesn't accumulate in the body, so the effects are not cumulative. Moderate exposure can cause respiratory system damage that persists even after exposure is over, however, so treatment may sometimes be necessary to manage any aftereffects.

Considerations

• Hydrogen sulfide poisoning is rare and occurs chiefly in certain settings in industry or in agriculture. H2S is produced by certain species of bacteria that degrade decaying organic matter, so it's often associated with sewage sludge or liquid manure; it's also a byproduct of some industrial processes like petroleum refining, mining and rayon manufacturing. Exposure to low concentrations is unlikely to cause any lasting effects; still, since high concentrations are so toxic, it's best to take all appropriate precautions when dealing with situations where the gas may have accumulated, as with liquid manure storage, for example.