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Health Effects of Hydrogen Sulfide: Dangers and Benefits

Updated on August 1, 2017
AliciaC profile image

Linda Crampton is a teacher with a first class honors degree in biology. She writes about human biology and the scientific basis of disease.

Hydrogen sulfide gas often has a rotten egg odor.
Hydrogen sulfide gas often has a rotten egg odor. | Source

The Significance of Hydrogen Sulfide

Hydrogen sulfide, or H2S, is a flammable, explosive, and toxic gas in the environment. It's known for its rotten egg smell and is sometimes called sour gas or stink damp. The gas is very dangerous at high concentrations. It's also found in our bodies, however, where it actually has health benefits.

H2S is released from decomposing organic matter, geothermal activity, and industry. It's widespread in the atmosphere but is more concentrated in some environments than in others. It's a potential problem in the oil and gas industries.

Hydrogen sulfide in the atmosphere can make breathing difficult and damage the nervous system. The more concentrated the H2S, the more pronounced its effects. It can be deadly at high concentrations.

Despite its dangers in the environment, hydrogen sulfide is a normal component of our bodies, where it's present in a very low concentration. It acts as a signaling molecule in the nervous system and probably in the circulatory system as well. Recent research suggests that low levels of the chemical have other important health benefits in humans. Once scientists have learned more about the action of H2S in the body it may be possible to use the chemical to treat health problems.

Farm animals produce a lot of manure, which needs to be removed periodically. When bacteria decompose manure they often produce hydrogen sulfide.
Farm animals produce a lot of manure, which needs to be removed periodically. When bacteria decompose manure they often produce hydrogen sulfide. | Source

Sources and Location of the Chemical

Hydrogen sulfide in the environment comes from both natural and industrial sources. Bacteria produce the chemical when they decompose material that was once living, such as dead bodies and animal or human wastes. The chemical may also be released from sulfur springs and volcanic eruptions.

H2S is common in places with a large quantity of decaying organic matter and a low concentration of oxygen. It's heavier than air and tends to collect in low lying areas, including underground sewers, animal manure pits, swamps, and salt marshes.

Industries in which people may be exposed to hydrogen sulfide include oil refineries, pulp and paper mills, mines, solid waste landfills, wastewater treatment plants, and tanneries. Workers at commercial companies that handle manure may also be exposed to the chemical.

It's not always easy to smell hydrogen sulfide. Some people are more sensitive to it than others.
It's not always easy to smell hydrogen sulfide. Some people are more sensitive to it than others. | Source

How Can the Chemical Be Detected?

H2S is an invisible gas. It often has a rotten egg smell at lower concentrations and a sickly sweet smell at higher concentrations. After an initial odor there may be no smell at all, however. This is because the gas can deaden a person's sense of smell after they have been exposed to a high concentration for a short time or a low concentration for a long time. The smell may also be masked by the odor of other chemicals.

Some people can detect the presence of H2S at lower concentrations than other people. Fortunately, hydrogen sulfide detectors can monitor the air in potentially dangerous areas so that everyone is aware of the presence of the chemical.

Hydrogen Sulfide Dangers and Precautions

Possible Symptoms of Hydrogen Sulfide Poisoning

Hydrogen sulfide enters the lungs and is easily absorbed into the bloodstream. Very little is absorbed through the skin. H2S can cause severe skin irritations, however.

The symptoms produced by hydrogen sulfide poisoning depend on the concentration of the chemical and the length of the exposure. Exposure to a moderately low concentration of the chemical may cause the following symptoms:

  • eye, nose, and throat irritation
  • headache
  • nausea
  • stomach upset
  • dizziness
  • difficulty breathing due to irritation of the lungs
  • coughing
  • insomnia

As the exposure increases, a person may experience confusion, fatigue, and a condition called pulmonary edema. In this condition fluid collects in the air sacs of the lungs, making breathing very difficult.

Exposure to a high concentration of hydrogen sulfide may cause these additional symptoms:

  • low blood pressure
  • muscle cramps
  • lack of muscle coordination
  • inability to reason
  • loss of consciousness

Loss of consciousness followed by death may be very rapid in an area with a high concentration of hydrogen sulfide.

Structure of a Synapse

Source

Functions of Hydrogen Sulfide in the Nervous System

Nerves transmit electrical messages, or nerve impulses, in order to control the processes that take place in our bodies. A nerve impulse is passed from one neuron (nerve cell) to the next. There is a tiny gap between successive neurons.

When a nerve impulse reaches the end of a neuron, tiny vesicles (sacs) in the neuron release a chemical called a neurotransmitter. Neurotransmitter molecules travel across the gap between neurons, join to receptors on the membrane of the second neuron, and trigger the start of a new nerve impulse. The region where one neuron ends and another begins is called a synapse.

Some gases act as neurotransmitters. These include nitric oxide, carbon monoxide, and hydrogen sulfide. Carbon monoxide is another gas which is dangerous in the atmosphere but helpful in the low concentrations found in the body. The gaseous neurotransmitters aren't stored in vesicles like most other neurotransmitters, but they do influence the transmission of the nerve impulse and also affect other processes in the nervous system.

Functions in the Circulatory System

In mice, the lining of the blood vessels produces hydrogen sulfide. The chemical relaxes the muscles in the walls of the vessels, causing the blood vessels to expand. This process reduces blood pressure. The researchers who discovered this information believe that the same system works in humans. If so, hydrogen sulfide would have a similar function to nitric oxide, another gas that expands blood vessels.

It has been suggested—but not yet proved—that the beneficial effects of garlic on blood vessels and blood pressure are due in part to the production of hydrogen sulfide after garlic is eaten.

Hydrogen sulfide has helped rats with a disorder resembling Parkinson's disease.
Hydrogen sulfide has helped rats with a disorder resembling Parkinson's disease. | Source

Possible Health Benefits of Hydrogen Sulfide

Hydrogen sulfide may have anti-aging benefits. University scientists from China suggest that it slows aging in several ways. They say that "the evidence is mounting" that the chemical activates an enzyme called SIRT1. This enzyme is thought to influence lifespan. The scientists also say that H2S interacts with a gene known as "klotho", which is involved in anti-aging processes. In addition, research suggests that H2S reduces inflammation and is an antioxidant.

Researchers have noticed that the normal level of hydrogen sulfide in the brain is greatly reduced in people with Alzheimer's disease. They have also noticed that rats suffering from a disorder similar to Parkinson's disease have low levels of H2S in their brains. When the affected rats in one experiment were given the chemical, their movement problems disappeared.

Suspended Animation in a Worm

Hydrogen Sulfide and Suspended Animation

A worm called Caenorhabditis elegans, or C. elegans, enters a state of suspended animation when exposed to hydrogen sulfide. Its rapid movements slow and then stop. Once the H2S is removed from the air, the worm returns to its active state, apparently unharmed. C. elegans is a popular animal in anti-aging studies.

Mice also enter a state resembling suspended animation when they are exposed to H2S. In one experiment, the gas caused the breathing rate of mice to drop from 120 breaths per minute to less than 10 breaths per minute. Their metabolic rate decreased by 90% and their core temperature fell from 37 degrees Celsius to around 11 degrees Celsius. After six hours of exposure to hydrogen sulfide the mice were exposed to normal air. Their body conditions returned to normal and tests showed that no apparent harm was done.

Scientists have suggested that a state of suspended animation induced by hydrogen sulfide could be useful in humans. It might be helpful in certain disease conditions and during long-distance space travel, for example.

Hydrogen sulfide is a very interesting chemical. It can be dangerous and deadly in the environment or helpful in our bodies. Hopefully researchers will soon learn how to use the chemical to benefit our lives.

References

A Hydrogen Sulfide Management PDF from the CDC (Centers for Disease Control and Prevention)

Cardioprotective Effects of H2S from PNAS (Proceedings of the National Academy of Sciences of the United States of America)

H2S in the Nervous System from Boston University

American Society for Microbiology. (2013, January 29). Hydrogen sulfide: The next anti-aging agent?. ScienceDaily. Retrieved July 31, 2017 from www.sciencedaily.com/releases/2013/01/130129121945.htm

Suspended Animation in Mice from the BBC

© 2013 Linda Crampton

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    • AliciaC profile image
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      Linda Crampton 2 years ago from British Columbia, Canada

      Thank you very much for the comment, Vellur. Hydrogen sulfide is an interesting chemical, even though it's potentially dangerous.

    • Vellur profile image

      Nithya Venkat 2 years ago from Dubai

      Suspended animation through hydrogen sulfide is amazing! I can still recollect the smell of hydrogen sulfide in the chemistry lab, it was awful! Well it is scary that it deadens the sense of smell when exposed to a high concentration. Informative and useful great hub, learned a lot.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much for the visit, Dianna. I appreciate your comment!

    • teaches12345 profile image

      Dianna Mendez 4 years ago

      I remember doing some science experiments in high school around this and they did smell! Great post and well done. I learned much from reading it.

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Ingenira. Yes, hydrogen sulfide often has a horrible smell! The smell can actually be a good warning sign, but unfortunately it's not always present.

    • Ingenira profile image

      Ingenira 4 years ago

      It is interesting to know that Hydrogen Sulfide can be dangerous and deadly in the environment or helpful in our bodies. I have smelled it a few times, never liked it and ran away from it .... lol.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thanks for the comment, Deb. The dual nature of hydrogen sulfide is certainly interesting!

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      Who would have thought that something so deadly can be so beneficial in smaller doses? interesting material, as usual!

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      What a dramatic and very sad story, Beckie. Hydrogen sulfide in the environment is a frightening substance. Thank you for the comment and for sharing the information.

    • shiningirisheyes profile image

      Shining Irish Eyes 4 years ago from Upstate, New York

      Alicia - Very interesting article. I do be this gas was also responsible for wiping out an entire town years ago. They discovered underground gas seeping from the bottom of a lake. Once the gas reached the air, the lake winds blew it to residences surrounding the lakeside. Very deadly indeed.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much, Bill. I appreciate your votes and the share, as always!

    • bdegiulio profile image

      Bill De Giulio 4 years ago from Massachusetts

      Very interesting Alicia. I know the smell well. You are a wealth of knowledge. Thank you again for the education. Voted up, interesting, shared, etc...

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Seeker7. I hope that hydrogen sulfide can be used as a medical treatment as soon as possible. Scientists need to understand more about how it works and what concentrations are necessary and safe in the body first, but it would be wonderful if it could be used as a medication. Thank you very much for the comment and the vote.

    • Seeker7 profile image

      Helen Murphy Howell 4 years ago from Fife, Scotland

      This is a fascinating hub Alicia. All this information is new to me as I didn't know anything about this gas - well apart from the smell that is! I was really interested in H2S's relationship to Parkinson's Disease as my Dad has this - I've maybe mentioned this before.

      I also found taking garlic and the health of the circulatory system fascinating as I've taken garlic for many years as it was believed that it was helpful for the heart etc.

      A fascinating and thoroughly enjoyable hub - voted up!!

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, drbj. Yes, it is interesting that a substance can be both dangerous and helpful, depending on its concentration. The ability of hydrogen sulfide to put at least some animals into suspended animation is intriguing!

    • drbj profile image

      drbj and sherry 4 years ago from south Florida

      Isn't it fascinating, Alicia, how a substance like hydrogen sulfide in large concentrations can be so dangerous on one hand and perhaps extremely beneficial on the other. Guess those sci-fi movies of long-distance space travelers in suspended animation may one day be a possibility with the help of this smelly substance.

    • AliciaC profile image
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      Linda Crampton 4 years ago from British Columbia, Canada

      Thanks, Pet Artist. Yes, it's good to be aware of the possible warning signs of hydrogen sulfide presence!

    • Pet Artist profile image

      Pet Artist 4 years ago

      Great resource. Never smelled hydrogen sulfide before, but the next time I smell rotten eggs I'll be doing more than just checking the fridge!

    • AliciaC profile image
      Author

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you, Bill. It's good that hydrogen sulfide does have such an impressive smell. If the smell is obvious it may be a great warning system!

    • billybuc profile image

      Bill Holland 4 years ago from Olympia, WA

      Great information, Alicia. I have smelled it and you are right about the rotten egg smell.