Introduction
Hydrogen sulfide is a toxic, colorless, and highly inflammable gas with rotten eggs' odor. It is naturally present in manure gas, swamps, sewage, geysers, hot springs, and volcanoes. It is used in oil and gas and paper mills, food processing, and tanneries. The chemical is heavier than air and accumulates in poorly ventilated, low-lying enclosed areas. It is flammable and exists in the gaseous state under normal conditions. People at low concentrations in the air can smell it. It is mainly used for the production of sulfuric acid and sulfur.
Hydrogen sulfide exposure can irritate the respiratory system and the eyes. Poisoning mostly occurs through inhalation of the substance. High-level exposure can result in fatal toxicity, while low-level exposure can irritate the skin and mucous membranes.
What Happens When Hydrogen Sulfide Enters the Environment?
Hydrogen sulfide can enter water, soil, or air from where it is used or produced. It is mainly released in the gaseous state and spreads in the air. The substance can remain in the air from 1 to 42 days. When in contact with air, hydrogen sulfide can be converted into sulfates and sulfur dioxide. In water, the levels remain low as the substance evaporates readily. In the soil, hydrogen sulfide is changed to sulfur by soil bacteria.
What Are the Different Ways in Which One Can Get Exposed?
One can get exposed to hydrogen sulfide through contaminated air or water. Some of the workers who are at risk of hydrogen sulfide exposure are:
- Natural gas and petroleum workers who are involved in drilling and refining.
- Wastewater treatment industry workers.
- Agricultural workers who work on farms with manure storage pits.
- Workers in Rayon textile manufacturing plants.
- People residing near a wastewater treatment plant, a farm with manure storage pits, gas and oil drilling operations, etc., are at increased risk of exposure.
What Are the Health Hazards Associated With Hydrogen Sulfide Exposure?
The respiratory system is the part of the body that is most affected by hydrogen sulfide exposure. Another body part that is mostly affected is the central nervous system, which consists of the brain and the spinal cord. Low-level exposure (2 to 100 ppm) can result in the following symptoms:
- Tiredness.
- Headache.
- Breathing difficulty.
- Irritation to nose, throat, and eyes.
- Memory loss.
- Loss of balance.
High-level exposure (100 to 2000 ppm) can result in the following symptoms:
- Throat irritation.
- Eye irritation.
- Loss of smell.
- Drowsiness.
- Altered breathing.
- Pink eyes or conjunctivitis.
- Fluid in lungs or pulmonary edema.
- Symptom severity increases with time.
Exposure greater than 500 ppm results in:
- Severe eye damage.
- Rapid unconsciousness.
- Death can occur due to direct exposure in an enclosed environment without ventilation.
The clinical effects of acute exposure are:
- Skin Exposure - Dermal exposure can result in a burning sensation, itching, erythema, and pain. Bluish skin discoloration or cyanosis is seen in some cases. Frostbite injury is seen in cases where direct exposure to liquified material occurs.
- Eye Exposure - Ocular exposure to hydrogen sulfide can result in severe eye irritation and damage. It can result in corneal abrasions and painful conjunctivitis. Ocular pain and blurred vision are also seen.
- Ingestion Exposure - Hydrogen sulfide can irritate the mucous membrane and cause nausea and vomiting.
- Inhalation Exposure - Hydrogen sulfide can be detected at low concentrations due to its unpleasant odor. So, even 2 to 15 minutes of low-concentration exposure can result in olfactory fatigue. Inhalation exposure can result in bronchitis, respiratory depression, breathing difficulty, pulmonary edema, cyanosis, and acute lung injury.
- CNS Effects - CNS (central nervous system) effects occur due to enzyme poisoning at the cellular level. After rapid alveolar absorption, hydrogen sulfide gets transported to the brain. Low-concentration exposure can result in CNS depression and symptoms like fatigue, dizziness, and drowsiness. Delirium, convulsions, and coma may occur due to acute exposure.
What All to Be Done in Case of Exposure?
Hydrogen sulfide exists in the gaseous state at room temperature. The medical personnel should take proper precautionary measures. Mouth-to-mouth artificial respiration should be avoided. Artificial respiration, if needed, should be given using a pocket mask with a one-way valve.
- The victim should be shifted to a well-ventilated area.
- Oxygen should be administered in case of breathing difficulty.
- Contaminated clothing should be removed.
- In case of skin or eye exposure, flush with running water for a minimum of 15 minutes.
- The frosted areas should be thawed with lukewarm water in contact with liquified gas.
- If burns are present, cool the skin with cold water.
Treatment procedures for the management of hydrogen sulfide poisoning in a healthcare facility are:
- Eye Exposure - Remove contact lenses, if any. Flush the eyes with running water or 0.9 percent saline for a minimum of 15 minutes. An ophthalmologic examination is to be done.
- Skin Contact - In case of skin exposure, wash with plenty of water and non-abrasive soap. In case of frostbite injury, the affected region is placed in a water bath at 40 to 42 degrees Celsius for fifteen to thirty minutes. Rewarming may result in increased pain; hence, narcotic analgesics may be needed.
- Inhalation Exposure - 100 percent oxygen is administered in case of inhalation exposure. A 72-hour monitoring is required to check for the development of pulmonary edema.
- Ingestion Exposure - Ingestion exposure is unlikely as hydrogen sulfide exists in the gaseous state.
How Does It Affect Children?
There is little information on the possible health hazards of hydrogen sulfide on children. The effects in exposed children should be the same as in exposed adults. There is no information on whether children are more sensitive to exposure. There is also no information on whether hydrogen sulfide can result in birth defects. Animal laboratory studies suggest that exposure to low concentrations of hydrogen sulfide during pregnancy produces no ill effects.
What Medical Tests Can Determine Hydrogen Sulfide Exposure?
Hydrogen sulfide and its metabolites can be detected in blood and urine tests. However, detecting these does not predict the health effects that can occur due to the exposure. These tests should be carried out immediately after exposure, as hydrogen sulfide and its metabolites are rapidly eliminated from the body.
Conclusion
Hydrogen sulfide gas is colorless with an unpleasant odor. Exposure can result in irritation of the eye, skin, and respiratory tract; mainly, exposure occurs through inhalation. High-level exposure can even result in death. Human activities produce hydrogen sulfide, which also exists naturally.
