Hydrogen Sulfide Toxicity

What is Hydrogen Sulfide Toxicity?

Hydrogen sulfide is a highly flammable and poisonous gas that doesn’t have any color. You can find it naturally in places like sewage systems, swamps, manure gas, hot springs, geysers, and volcanoes. Additionally, this gas is also used in various industries such as oil and gas, food processing, paper mills, and tanneries. Sometimes, it is even found in some homemade cleaning mixtures that are sadly used in suicide attempts.

Hydrogen sulfide poisoning happens when the gas is breathed in. In small amounts, it can irritate your skin and the lining of certain passages in your body like your nose, mouth, and eyes. In larger amounts, it can be deadly. One unique thing about this gas is that it smells like rotten eggs. But, when you’re exposed to it, it can stop your nose from detecting this smell, which can lead you to mistakenly think that you’re safe. If you’re exposed to large amounts of the gas, you might suddenly pass out. If you’re not moved away from the gas quickly, this can lead to death. Other signs of seriously harmful amounts of the gas include eye inflammation, liquid in the lungs, seizures, and heart and lung failure. The gas harms your body by preventing it from being able to use oxygen for energy and by creating harmful particles that damage your cells, leading to cell death. Unfortunately, there’s no cure for poisoning by this gas, so the only treatment is to support the body while it tries to recover. There’s still a lot that we don’t know about the effects of being exposed to low levels of this gas for a long time, but some evidence suggests that it can harm the nervous system and lead to long-term neurological problems.

What Causes Hydrogen Sulfide Toxicity?

Hydrogen sulfide is a toxic gas that can cause harm to the body in two ways. At first, it acts as an irritant, then it affects the body’s cells, hindering their ability to create energy. Breathing in the gas is the most common way it gets into the body, although it can also pass through the skin to a lesser extent.

This gas is heavier than air, making it likely to gather near the ground in places that aren’t properly aired out. It’s produced when bacteria break down proteins, such as those in rotting fish, sewage, and manure. It’s also found in the environment around volcanoes, caves, sulfur springs, and natural gas deposits.

A notable example of a population regularly exposed to this gas are the Maori people in Rotorua, New Zealand, where sulfur springs and geothermal sources of hydrogen sulfide are common.

The gas is the second most common cause of deadly gas inhalation at work, with carbon monoxide being the first. There are many industries where exposure to this gas is a risk. These include the paper industry, rubber production, the leather industry, and agriculture, among others — particularly those who work in sewers or handle livestock manure.

One of the striking effects of this toxicity is its ability to cause a sudden, temporary loss of consciousness known as ‘knockdown’. This is likened to a puppeteer releasing the strings of a marionette. However, this gas also poses a risk to those trying to rescue victims, with up to one in four fatalities involving rescuers.

Since hydrogen sulfide can catch fire, there’s also a risk of explosions, leading to burns and physical injuries. If someone survives exposure to this gas, they should be checked for these kinds of injuries to ensure they get the care they need.

There have been tragic cases where hydrogen sulfide is used for self-harm, with individuals intentionally creating the gas by mixing common household chemicals. This is incredibly dangerous and can cause a rapid death in confined spaces, like a car. This method of self-harm is also hazardous for rescuers and bystanders.

Given its deadly effects and relative ease of production, hydrogen sulfide has been discussed as a potential chemical weapon in extremist materials.

Risk Factors and Frequency for Hydrogen Sulfide Toxicity

Hydrogen sulfide is a dangerous gas that can cause health problems for people in over 80 different job types. Other than carbon monoxide, this gas is the second most common cause of death from gas inhalation at work. However, cases of acute hydrogen sulfide poisoning can be quite rare and unpredictable.

There have been instances where accidents have resulted in fatalities due to this gas. In 1950 in Mexico, a refinery explosion that released hydrogen sulfide ended up hospitalizing 320 people and caused 22 deaths. In 2003 in China, an accident involving a gas pipe explosion led to 243 fatalities.

Aside from work-related exposures, using hydrogen sulfide as a suicide method became a trend in Japan in 2007. In 2008, 200 people died from suicide using this method. Interestingly, around 80% of attempts using this method also resulted in harm to nearby first responders and civilians. Between 1999 and 2007 in the United States, there were 45 reported deaths from suicides that involved hydrogen sulfide.

Hydrogen sulfide is a health risk in more than 80 occupations.
After carbon monoxide, it’s the second most common cause of fatal gas inhalation at workplaces.
Hydrogen sulfide cases are rare but unpredictable.
There have been major accidents in Mexico and China causing deaths due to this gas.
It became a method of suicide in Japan in 2007, causing harm to not only the person attempting suicide but also those nearby.
From 1999 to 2007, the US reported 45 deaths from hydrogen sulfide involved suicides.

In a 2022 report from America’s poison centers, they recorded 779 exposures to this gas. Of these exposures, 762 were unintentional and resulted in sending 323 of the affected individuals to the hospital. Out of all these cases, there were 3 deaths. One alarming case was a woman who committed suicide by locking herself in her car with a bucket of chemicals that released the gas. She was found unresponsive and unfortunately passed away on the second day in the hospital due to the consequences of hydrogen sulfide poisoning.

Signs and Symptoms of Hydrogen Sulfide Toxicity

Hydrogen sulfide toxicity is a condition that could potentially affect anyone found passed out in a confined space. It usually involves people who may have been exposed to hazardous environments like petroleum plants or sewers, or visited places with natural occurrences of the gas, such as hot springs or volcanoes. Often, patients report a strong smell similar to rotten eggs just before symptoms begin. However, continuous exposure to hydrogen sulfide can damage the nerves responsible for smell, making it harder to detect the strong odor. This is why a lack of smell doesn’t necessarily mean that there’s no risk of hydrogen sulfide toxicity.

An unusual sign of this condition could include silver jewelry or coins turning a darker, almost black color. This happens when the hydrogen sulfide in the environment interacts with the silver and turns it into silver sulfide.

The severity of symptoms from hydrogen sulfide exposure depends on the concentration of the gas. For example:

Low-level exposure: Symptoms can include irritated mucous membranes, headaches, inability to sleep, dizziness, and fatigue.
High-level exposure: Symptoms can ramp up to include cough, difficulty breathing, coughing blood, nausea, vomiting, and dizziness.
Very high-level exposure: This can cause extremely dangerous symptoms like heart attacks, sudden loss of consciousness, seizures, and heart and lung failure. It can also lead to particular signs on bodily examination like eye inflammation, a green-gray line on the gums, throat inflammation, slow heart rate, extreme agitation, and bluish or grayish skin.

Other severe symptoms can also develop with increased exposure, including fluid build-up in the lungs, bloody cough, and delayed injury to the cornea. Extremely high levels of the gas can even result in neurological issues, like seizures, coma, and sadly, even death.

The duration of the exposure to the gas also plays a crucial part in the impact of the toxicity. For instance, prolonged exposure to even a small amount of hydrogen sulfide can result in “Gas eye,” a condition where one experiences inflammation in the front part of the eye and may see changes in color and vision. Symptoms may include seeing halos around objects, twitching of the eyelids, teary eyes, and sensitivity to light.

A combination of sudden unconsciousness, fluid in the lungs, inflammation of the eyes, and smell detection followed by loss of smell is a unique group of symptoms specifically observed in cases of hydrogen sulfide toxicity.

Testing for Hydrogen Sulfide Toxicity

Currently, there are no easily accessible biological markers or direct measurements for hydrogen sulfide poisoning available for use in a medical setting. So, it’s not possible to confirm this type of poisoning quickly.

Your doctor can take a blood sample to check for signs of this kind of poisoning. If there’s more than 0.05 mg/L of sulfide in your blood, it could be a sign of abnormality. However, this blood sample must be taken within two hours of exposure and tested straight away.

Testing for hydrogen sulfide exposure can also be done by checking the level of thiosulfate in your blood and urine. Thiosulfate is a substance that can indicate hydrogen sulfide exposure. However, this kind of test is not available in most hospitals and can’t be used to guide treatment. The test for urine thiosulfate is mostly used in workplaces to monitor long-term, low-level exposure to hydrogen sulfide.

Another check your doctor might do is an arterial blood gas test. This is a blood test that measures the levels of certain gases in your blood. If this test shows high acid and lactate levels, it can suggest hydrogen sulfide toxicity. But other conditions showing similar results, so, this test isn’t entirely specific for hydrogen sulfide poisoning. Like cyanide, hydrogen sulfide inhibits oxygen utilization in your body, so a high level of oxygen on a venous blood gas sample can be a sign of exposure.

It’s estimated that up to 20% of patients who are exposed to hydrogen sulfide gas may show signs of fluid in the lungs (pulmonary edema). So your doctor will likely order a chest X-ray to rule out this condition.

Lastly, doctors must assess you for any physical injuries, as many patients exposed to hydrogen sulfide suffer physical injuries from falling down due to the toxic effects of the gas. This assessment might involve scans of your head and neck region – known as computed tomography (CT) scans – to look for brain injuries or damage to the cervical spine (the part of your spine in your neck).

Treatment Options for Hydrogen Sulfide Toxicity

If you’ve been exposed to hydrogen sulfide, which is a harmful gas, the first step is to quickly get away from the source of the gas to avoid further exposure. Rescuers who help you must also protect themselves by wearing personal protective equipment to avoid getting sick from the gas. It’s important to wash your skin and eyes with water if they’re irritated and to take off the clothes you were wearing during exposure as they can continue giving off the gas. This step is important for your safety as well as the healthcare workers who’ll be treating you.

Once you’re safe, you’ll be given oxygen as quickly as possible. If you fell and are unconscious or have injuries as a result of exposure, you’ll be assessed for signs of trauma and then treated according to Advanced Trauma Life Support protocol, which is a planned response to serious injury.

There is currently no antidote for hydrogen sulfide. However, medical professionals can treat the symptoms and effects by providing proper care. This might involve giving fluids and medications to manage low blood pressure and to help with ventilation and oxygen supply. Sodium bicarbonate (a kind of salt used in medicine to treat certain conditions) might also be given based on test results to manage your body’s acid-base balance.

One treatment option is to give an intravenous dose of sodium nitrite. This medicine causes methemoglobin to accumulate in the blood at low levels. Methemoglobin is a form of hemoglobin – the molecule responsible for carrying oxygen in the blood. As hydrogen sulfide is more attracted to methemoglobin than it is to cytochrome oxidase (a protein complex involved in cell respiration), the idea is that this will help restore cell respiration. After treatment, your methemoglobin levels will be checked and if they’re too high, a medicine called methylene blue may be given. However, this treatment needs to be given quickly and is not without its own risks.

Hydroxocobalamin and its analog cobinamide have been investigated as potential alternative treatments for hydrogen sulfide poisoning due to their similarity to treatments for cyanide poisoning. These medicines aim to bind the hydrogen sulfide in the blood, stopping the toxic effects. Although cobinamide has two binding sites for hydrogen sulfide, compared to one site on hydroxocobalamin, the use of these treatments is still being researched due to conflicting evidence from animal tests. If someone is very ill from hydrogen sulfide toxicity, giving either sodium nitrite or hydroxocobalamin could be helpful.

Methylene blue, an antioxidant, could also be helpful as it has the potential to oxidize sulfide, trap more hydrogen sulfide in the blood, restore cells redox potential, and bring back normal cell function. But more research is needed to see how effective it may be in treating humans.

Another approach to treating hydrogen sulfide poisoning has been the use of a hyperbaric oxygen chamber, although the evidence to support this is limited. Hyperbaric oxygen therapy exposes the body to pure oxygen under increased pressure, which could help improve the delivery of oxygen to essential organs. However, not every medical center can provide this type of therapy. Normobaric oxygen therapy, a standard oxygen therapy treatment, shouldn’t be delayed in order to provide hyperbaric oxygen. The priority is to start treatment as soon as possible.

When dealing with symptoms that look like hydrogen sulfide poisoning, it’s important to remember that other harmful gases can cause similar symptoms. Detail is key in telling these toxic gases apart, as their symptoms can be quite similar. If a person is suspected of having hydrogen sulfide poisoning, here are other possible causes of their symptoms to consider:

Cyanide: This gas works in a similar way to hydrogen sulfide and can cause overlapping symptoms like seizures, rapid breathing, and coma. However, cyanide poisoning might also cause headaches, nausea, vomiting, irregular heartbeats, bluish skin, and failure of the kidneys and liver. Cyanide typically smells like bitter almonds, unlike the rotten egg smell of hydrogen sulfide.
Carbon monoxide poisoning and methemoglobinemia: These conditions can also cause headaches, shortness of breath, and confusion, but they are likely to come with chest pain, nausea, and vomiting as well. A test called co-oximetry can be used to rule out these possibilities.
Exposure to ammonia, chlorine, and sulfur mustard gases: These gases can irritate the mucous membranes in the body and can lead to rapid clinical deterioration.
Hydrocarbons: Gases in this category commonly cause shortness of breath and coughing and may lead to difficulty in breathing. These infiltrates can be spotted in a chest X-ray. They can also cause central nervous system depression and dysfunction of the heart muscle.
Sudden unexpected death in epilepsy (SUDEP): This condition can mimic hydrogen sulfide toxicity, as it can induce a seizure, followed by death.

Taking these possibilities into account and conducting necessary tests can lead to a more accurate diagnosis.

What to expect with Hydrogen Sulfide Toxicity

For people who have been exposed to high levels of hydrogen sulfide and cannot quickly move away from the source, death can occur swiftly. Those who do manage to recover often seem to return to their regular functioning level. However, these individuals are at a high risk for leftover problems with their nervous systems. This risk is made even more complicated by the potential for brain injuries and a lack of oxygen to the brain due to trauma.

There’s conflicting information about the long-term impact of exposure to low levels of hydrogen sulfide. Some studies conducted on the residents of Rotorua, New Zealand, who live near geothermal vents, found no relationship between hydrogen sulfide exposure and their thinking abilities. But, they had a higher risk for respiratory diseases like chronic obstructive pulmonary disease, flu, and pneumonia. But this data isn’t very strong, as there were other factors that the data did not consider, like mercury and other types of sulfide levels.

Similarly, studies involving sewer workers in Egypt found high instances of cognitive impairment, issues such as lack of focus, memory problems, and headaches. However, these symptoms are fairly vague and could be caused by other factors unrelated to hydrogen sulfide exposure, such as job dissatisfaction and lower socio-economic status, which were also common among these workers.

Possible Complications When Diagnosed with Hydrogen Sulfide Toxicity

Exposure to high levels of hydrogen sulfide can cause several health problems, these include:

Difficulty in smelling due to damage to nerves involved in olfaction
Eye irritation resulting in altered vision and distorted color perception
Fluid in the lungs leading to severe respiratory issues
Sudden and severe heart issues
Long-term psychological and cognitive issues, including changes in personality, feeling low, and a decrease in thinking ability
Potential death

Preventing Hydrogen Sulfide Toxicity

The best way to avoid exposure to hydrogen sulfide, a harmful gas often found in places like volcanoes, sewers, swamps, and areas with natural gas, is to stay away from these areas. For people who work in industries where exposure to such toxic substances is possible, it’s essential to use the right safety gear to prevent harmful health effects.

One of the most effective safety measures is to wear a mask that filters out harmful particles. This is because inhaling the gas is the most common way that it can cause harm. There are federal safety rules that limit how much exposure to this gas is acceptable, and these should always be followed carefully.

Frequently asked questions

Hydrogen sulfide toxicity occurs when the gas is inhaled in large amounts, leading to serious harm and potentially death. It can cause symptoms such as eye inflammation, liquid in the lungs, seizures, and heart and lung failure. The gas prevents the body from using oxygen for energy and creates harmful particles that damage cells, resulting in cell death.

Hydrogen sulfide toxicity is relatively rare but unpredictable.

Signs and symptoms of Hydrogen Sulfide Toxicity include: - Irritated mucous membranes - Headaches - Inability to sleep - Dizziness - Fatigue - Cough - Difficulty breathing - Coughing blood - Nausea - Vomiting - Heart attacks - Sudden loss of consciousness - Seizures - Heart and lung failure - Eye inflammation - Green-gray line on the gums - Throat inflammation - Slow heart rate - Extreme agitation - Bluish or grayish skin - Fluid build-up in the lungs - Bloody cough - Delayed injury to the cornea - Neurological issues (seizures, coma, and death) - "Gas eye" (inflammation in the front part of the eye, changes in color and vision) - Seeing halos around objects - Twitching of the eyelids - Teary eyes - Sensitivity to light A combination of sudden unconsciousness, fluid in the lungs, inflammation of the eyes, and smell detection followed by loss of smell is a unique group of symptoms specifically observed in cases of hydrogen sulfide toxicity.

Hydrogen sulfide toxicity can occur through inhalation of the gas, exposure to the gas through the skin to a lesser extent, or prolonged exposure to even a small amount of hydrogen sulfide.

The other conditions that a doctor needs to rule out when diagnosing Hydrogen Sulfide Toxicity are: - Cyanide poisoning - Carbon monoxide poisoning and methemoglobinemia - Exposure to ammonia, chlorine, and sulfur mustard gases - Hydrocarbons - Sudden unexpected death in epilepsy (SUDEP)

The types of tests that a doctor would order to properly diagnose hydrogen sulfide toxicity include: 1. Blood sample to check for signs of poisoning, specifically measuring the level of sulfide in the blood. 2. Testing the level of thiosulfate in the blood and urine, which can indicate hydrogen sulfide exposure. 3. Arterial blood gas test to measure the levels of certain gases in the blood, such as acid and lactate levels. 4. Chest X-ray to rule out pulmonary edema (fluid in the lungs). 5. Scans of the head and neck region, such as computed tomography (CT) scans, to assess for physical injuries. 6. Assessment for signs of trauma and physical injuries from falling down due to the toxic effects of the gas. It's important to note that there are currently no easily accessible biological markers or direct measurements for hydrogen sulfide poisoning, so these tests are used to assess for signs and indications of exposure and toxicity.

Hydrogen sulfide toxicity is treated by quickly getting away from the source of the gas to avoid further exposure. Rescuers must wear personal protective equipment to protect themselves. Washing the skin and eyes with water is important if they are irritated, and removing the clothes worn during exposure is necessary as they can continue giving off the gas. Oxygen is given as quickly as possible, and if there are injuries or unconsciousness, the person will be assessed for signs of trauma and treated accordingly. While there is no antidote for hydrogen sulfide, medical professionals can treat the symptoms and effects by providing proper care, such as giving fluids and medications to manage low blood pressure and help with ventilation and oxygen supply. Sodium bicarbonate and intravenous doses of sodium nitrite or hydroxocobalamin may also be given. Methylene blue and hyperbaric oxygen therapy are other potential treatment options, but more research is needed to determine their effectiveness.

The side effects when treating Hydrogen Sulfide Toxicity include: - Difficulty in smelling due to damage to nerves involved in olfaction - Eye irritation resulting in altered vision and distorted color perception - Fluid in the lungs leading to severe respiratory issues - Sudden and severe heart issues - Long-term psychological and cognitive issues, including changes in personality, feeling low, and a decrease in thinking ability - Potential death

The prognosis for hydrogen sulfide toxicity depends on the level of exposure and the promptness of treatment. If a person is exposed to high levels of hydrogen sulfide and cannot quickly move away from the source, death can occur swiftly. Those who do recover often return to their regular functioning level, but they are at a high risk for long-term problems with their nervous systems. The long-term impact of exposure to low levels of hydrogen sulfide is still uncertain and conflicting studies have been conducted.

A toxicologist or a physician specializing in occupational medicine should be consulted for Hydrogen Sulfide Toxicity.