What is Hydrazine Toxicology?

Hydrazines are a type of chemical compound. They include two nitrogen atoms linked together by what is called a ‘covalent bond’. These types of compounds can also include up to four extra parts known as ‘alkyl substituents’. A simpler way to understand it is that they are a kind of building block in chemistry.

There are certain hydrazine compounds and their similar compounds that can be harmful to humans if they come into contact with them. This is referred to as ‘toxicity’.

Some commonly found examples of these harmful compounds are hydrazine, hydrazones, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and monomethylhydrazine (MMH). Hydrazine is a clear and colorless liquid chemical that smells somewhat like ammonia.

In this specific context, the term ‘hydrazines’ is used to refer specifically to hydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and monomethylhydrazine.

What Causes Hydrazine Toxicology?

Hydrazine and its related compounds have many uses in fields like industry, the military, and medicine. Because it burns quickly and reacts strongly with oxygen, it was first used by German scientists as the main part of rocket fuel during World War II. After the war, hydrazines gained popularity due to their power and reliability, along with their liquid properties that are similar to water. From the 1970s up until now, hydrazines have been used in spacecraft fuel and missile propulsion.

Hydrazines are known for their ability to reduce other compounds, meaning they can help certain chemicals lose oxygen, gain hydrogen, or gain electrons. This attribute makes hydrazines useful in several industries. They can be used in the making of foaming or blowing agents for plastic production, in creating agricultural products (like substances that regulate plant growth, kill weeds, kill fungi, and kill pests), and in making polymers (which are often used in plastics). Hydrazines are also used to remove oxygen from boiler water and water-heating systems to prevent them from rusting.

Naturally occurring hydrazines are not common but can be found in certain types of mushrooms, namely the Gyromitra and Agaricus species. The Gyromitra mushrooms contain gyromitrin (n-methyl-N-formyl hydrazone), a toxin that turns into monomethylhydrazine (a harmful compound) when it comes into contact with water. In severe cases of poisoning, monomethylhydrazine can cause seizures. Hydrazine has also been found in small amounts in tobacco, but there have been no documented cases of toxicity in humans from this source.

Risk Factors and Frequency for Hydrazine Toxicology

There have been many studies looking into the impact of hydrazine exposure, which can be separated into acute (short-term) and chronic (long-term) exposures. This research has given us much important information.

Acute Exposure:

This type of exposure often happened to military personnel who worked with hydrazine.
There have been cases of people ingesting or breathing in the substance, often resulting in serious symptoms. However, treatments have shown to be effective.
Some people have even died from hydrazine exposure, for example, a machine worker was repeatedly exposed for six months.
Others have suffered serious injuries, such as a man who fell into a coma after an industrial explosion exposed him to hydrazine.
Hydrazine can also affect the skin, commonly happening through jobs involving gold-plating, chicken feed additives, herbicides, or steam power plants.

Chronic Exposure:

A common reason for studying long-term exposure is to identify if hydrazine can cause cancer. Most of the studies on this matter include people exposed to other chemicals, making it hard to pinpoint the sole effect of hydrazine.
One study of men who worked at a hydrazine plant found their rates of death and cancer were not significantly higher than normal.
Another study of 130 men found a higher incidence of cancer in those heavily exposed, although the increase disappeared when excluding skin cancers.
An extensive study of aerospace workers, potentially exposed to hydrazine for at least two years, showed an increased risk of several types of cancer. However, this work has faced criticism due to the presence of other chemicals.
The World Health Organization (WHO) and the Agency for Toxic Substances and Disease Registry (ATSDR) both expressed concerns about occupational exposures, especially in areas associated with hydrazine production, rocket launching, and aircraft fueling.

Signs and Symptoms of Hydrazine Toxicology

Hydrazine toxicity can be recognized by knowing the common occupational and environmental risk factors. People who work in facilities that store or produce rocket fuels, such as propulsion testing facilities, military installations, aerospace facilities, and hazardous waste sites, are often exposed to hydrazine. Certain medical conditions, like tuberculosis, and activities like mushroom forging, can also lead to hydrazine exposure. Hydrazine, which can be found in some Tuberculosis medicine, and monomethylhydrazine (MMH), found in certain mushrooms, are some of the substances that can lead to hydrazine toxicity.

The toxicity can happen through inhaling, swallowing, or touching hydrazine, and the exposure can be acute (less than 14 days), intermediate (15 to 364 days), or chronic (more than 365 days). Chronic exposure to hydrazine can cause symptoms that are similar to those of acute exposure, but it also increases the risk of developing various types of cancer, such as lung, lymphopoietic, liver, colorectal, and skin cancers.

People who are exposed to hydrazine through their skin, such as those working in the gold-plating industry, chicken feed additives, herbicides, or steam power plants, may experience skin irritation and a necrosis, which is a type of skin tissue death, within an hour. Chronic dermal exposure can also lead to the development of skin cancers.

Inhalation of hydrazine can result in symptoms such as difficulty breathing, a sore throat, a burning sensation in the face and nose, and chest tightness.
It can also lead to severe lung conditions like pulmonary edema, pleural effusions, and even death.
Neurotoxicity, which can range from nervous system depression to seizures, can occur from acute exposures to hydrazine and its derivatives.
Exposure to hydrazine can cause blood disorders like hemolytic anemia and methemoglobinemia, especially with MMH which has been described as having the most severe hemotoxic effects.
Hydrazine exposure can also damage the liver and cause an elevation in enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) within five hours that could last up to one week.

Chronic exposure to hydrazine may lead to symptoms similar to acute exposure but can also increase the risk of cancer. In fact, studies of aerospace workers with chronic inhalation exposure to hydrazine showed an increased risk in lung cancer mortality, even though an increase in lung cancer deaths was not statistically significant in workers at a hydrazine-manufacturing plant due to smaller sample sizes.

Testing for Hydrazine Toxicology

Swallowing hydrazine, a type of chemical, can cause serious harm to your body because of its strong alkaline nature. These harmful effects can actually cause your tissue to dissolve. If someone shows two out of these three symptoms – excessive salivation, a high-pitched wheezing sound when breathing, or vomiting – they should have an internal examination of their throat and stomach to see the level of injury. Additionally, emergency care may be needed to keep the patient’s airway open, especially if they have swelling due to the injury and they are struggling to swallow their saliva.

The patient’s mental state could range between decreased mental activity to over-excitement, and they could possibly experience seizures that do not respond to standard treatments. It’s also important to get a rapid sugar level test done since hydrazine is linked with low blood sugar levels.

When it comes to lung exams and chest X-rays, there could be signs of fluid buildup in the lungs or lung congestion. In some cases, blood tests might reveal that hydrazine has interfered with the oxygen-carrying capacity of the blood. Other blood tests may reveal a decrease in red blood cells or the presence of specific damaged red blood cells. Furthermore, basic health check tests (like metabolic panel and liver function testing) may show muscle tissue breakdown and varying degrees of liver damage. Sometimes, this liver injury can last up to a week and usually improves for survivors about four or five weeks after the initial contact with hydrazine.

Repeated exposure to hydrazine at work should also be checked out for certain cancers, as hydrazine can cause cancer. There are reports of cancers of the colon, skin, nose lining, lung, and liver, although these could be due to contact with other harmful substances. Furthermore, hydrazine contact has been linked with a certain type of skin cancer, known as basal cell carcinoma.

Treatment Options for Hydrazine Toxicology

If you’re exposed to hydrazine, a chemical compound often used in rocket fuel, there are several steps doctors will take to ensure your safety. The first action is to move you safely away from the exposure site, at least 75 feet. The next step is decontamination: all of your clothing would be removed and any exposed skin or eyes would be thoroughly cleaned with water for at least 15 minutes.

Emergency workers attending to the site of a hydrazine exposure would wear top-level protective equipment to safeguard their skin, eyes, and breathing from the chemical’s vapors. If you’ve suffered burns from the hydrazine contact, your skin would be treated in the same way as other injuries of this type. In serious instances, you may need specialized care at a burns center.

If you’ve breathed in hydrazine, medical professionals will provide supportive care such as supplemental oxygen and monitor your airways closely. In rare cases, fluid can build up in the lungs several hours after exposure, so you could need to be kept under watch for one to two days.

Swallowing hydrazine can potentially harm the upper airway and digestive system. In this scenario, the common method of swallowing a substance called ‘activated charcoal’ to bind and remove the toxin wouldn’t be suggested because hydrazine is absorbed too quickly into the body, making the charcoal potentially ineffective.

If hydrazine exposure leads to neurological issues like seizures or coma, a vitamin called pyridoxine may be administered. In severe cases where patients have active seizures, pyridoxine may be given until the seizures stop.

If hydrazine has affected your body’s ability to carry oxygen – a condition known as methemoglobinemia – standard treatment with a chemical called methylene blue will be used.

Once again, the key factor is that quickly reacting to symptoms and seeking immediate medical help can result in more effective treatment and better chances of recovery.

Different health issues can be caused by different substances or situations – here are some examples:

Issues affecting the lungs (also known as Pulmonary Irritants) can be caused by substances such as:

Phosgene
Chlorine
Ammonia
Ethylene oxide
Chloramine

Damage to the liver, or Hepatotoxicity, can be caused by toxins like those found in:

Amantia mushrooms

Alkali Caustic Burns, are skin burns caused by alkaline substances like:

Sodium hydroxide
Potassium hydroxide
Sodium hypochlorite
Ammonia

Seizures also have different causes such as:

Status epilepticus of unknown origin
Severe hyponatremia (low sodium in the blood)
Substance-induced
Sedative-hypnotic withdrawal
Hypoxic syncope (fainting due to lack of oxygen)
Anti-NMDA receptor encephalitis (a rare disease that affects the brain)

Finally, Central Nervous System (CNS) Depression or Coma could be due to:

Sedative-hypnotic intoxication
Opioid intoxication
Hepatic encephalopathy (a decline in brain function as a result of severe liver disease)
Hypoglycemia (low blood sugar)
Cerebrovascular accident (also known as a stroke)

What to expect with Hydrazine Toxicology

The outlook for hydrazine poisoning depends on how much was taken in and how it entered the body. Hydrazine is a chemical used in various industries, and long-term or large exposure can lead to poisoning.

There have only been 2 recorded cases of death from direct hydrazine poisoning. In most cases, people who have been exposed to hydrazine see a quick improvement in symptoms that are related to the nervous system and also recovery from liver injury.

However, there have been instances where the damage to the nervous system and the liver has been long-lasting. This outlook doesn’t include the effect of drugs like isoniazid, which have hydrazine as a by-product when they breakdown.

Possible Complications When Diagnosed with Hydrazine Toxicology

Hydrazine exposure can lead to a variety of toxic effects on different parts of the body. It impacts the lungs and respiratory system, causing irritation of the mucus membranes, fluid around the lungs, and delayed fluid accumulation in the lungs.

It harms the nervous system, potentially causing depression of the central nervous system, coma, uncontrolled muscle shaking, and prolonged seizures that don’t respond to treatment.

Moreover, it can cause skin problems like rashes and a rare type of skin decay known as liquefactive necrosis. The liver could also be severely affected, potentially leading to sudden liver failure.

The kidneys are not immune from damage, as hydrazine can lead to a condition where muscle tissue breaks down, releasing muscle fiber into the bloodstream (rhabdomyolysis).

It also affects the blood, leading to conditions like an increase of methemoglobin in the blood, and destruction of red blood cells.

In the long term, exposure to hydrazine might potentially cause a myriad of cancers. These include cancers of the lungs, lymphatic system, skin, colon, rectum, and liver.

Toxic Effects of Hydrazine:

Mucosal irritation, pleural effusion, delayed pulmonary edema
CNS depression, coma, clonus, refractory seizures
Dermatitis and liquefactive necrosis
Fulminant hepatic failure
Rhabdomyolysis
Methemoglobinemia and hemolytic anemia
Potential lung, lymphopoietic, skin, colorectal, and liver cancers

Preventing Hydrazine Toxicology

It’s important for people who may come into contact with hydrazine, such as those working in manufacturing or in the military, to understand the recommended exposure limits to prevent harmful effects. Hydrazine is a hazardous substance, and the National Institute of Occupational Health and Safety (NIOSH) has established safety standards to protect against its harmful effects.

According to NIOSH, the exposure level at which people may begin to feel discomfort or irritation from airborne hydrazine is 0.1 parts per million (ppm). If exposed to 1.6 ppm of airborne hydrazine over an 8-hour period, people may experience lasting health issues. More severely, exposure to 4.4 ppm over 8 hours could lead to life-threatening conditions or even death.

In general, NIOSH recommends an exposure limit of 0.03 ppm for up to 2 hours. Furthermore, hydrazine has an ammonia-like smell which becomes noticeable at levels of 3 to 4 ppm.

Other organizations like the Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists also offer guidelines. Additionally, there’s guidance for short-term public emergencies. Individuals exposed to hydrazine should be made aware of the symptoms that could occur from acute exposure.