Mustard gas

Three-dimensional structure of mustard gas.

The mustard gases are a family of chemicals used primarily as chemical weapons, also known as iperite, from Ypres, the Belgian city where the Germans first used it in 1915 during World War I. Mustard gas was synthesized to harass and incapacitate the enemy and contaminate the battlefield. Viktor Meyer describes his synthesis in the mid-1800s, but he was not the one who discovered it, nor was he the first to report its effects. The development of large-scale mustard gas production is due to the German chemist Wilhelm Steinkopf.

They are also called blistering agents, since when in contact with humans they cause blisters on the skin and mucous membranes, which usually entails consequences such as death by agonal suffocation.

Sulfur mustard

sulfur mustard (bis(2-chloroethyl)sulfane) is a type of chemical agent used as a weapon of war. Sulfur mustard is also known as mustard gas or "mustard agent” or by its military designations H, HD and HT.

It usually manifests itself in the gas phase, but it can also occur as a liquid (oily in texture), or solid. As a gas, it sometimes has an odor similar to garlic, onion, or mustard, and in other cases it has no odor. As a liquid and a solid, its color ranges from light yellow to brown. In any case, it is not found naturally in the environment.

As a weapon of war, sulfur mustard was first used during World War I. Although it is currently intended for medical use, since until a few years ago it was used for the treatment of psoriasis, a skin disease.

Nitrogen mustards

A soldier of World War I with mustard gas burns.

The nitrogen mustards (bis-2-chloroethylamines or β-haloalkylamines) produced in the 1920s and 1930s, also used as chemical warfare weapons. They were the first recorded case of the use of chemical weapons against the civilian population, in 1924 as revenge for the Annual disaster where many Spanish soldiers were executed after surrendering, during the Rif war, Spanish aviation dropped mustard gas, phosgene and other bombs toxic gases, on the Berber inhabitants and their villages. They are powerful irritants that damage the skin, eyes, and respiratory tract, enter body cells very quickly, and damage the immune system and bone marrow.

In the gas phase it can smell like fish, mold, soap or fruit. Below 21 °C it enters the liquid phase, where it assumes a clear, pale amber or yellow color and an oily texture, and is harmless. Due to this, during the winters of the Great War, the Germans launched projectiles with liquid nitrogenous mustard that, when falling on the battlefield, impregnated some enemy soldiers. These, unaware of the latent danger, took refuge in the galleries and conduits of the trenches where, when the chemical agent evaporated, it caused the death of anyone who did not escape outside in time. They are not found naturally in the environment.

They are also known by their military designations HN-1, HN-2 and HN-3.

They were the first alkylating agents with therapeutic application. They are mainly used as antineoplastics.

Mechanism of action

Nitrogenous mustards are highly reactive compounds because nitrogen, with its lone pair of electrons, can form aziridinium salts. These salts are strongly electrophilic species that react with nucleophiles to form a covalent bond. Due to its structure (bis-2-chloroethylamines), each molecule can give rise to two covalent bonds.

They can react with DNA since it is rich in nucleophilic centers, especially the nitrogen atom at position 7 of guanine. It constitutes one of the most reactive groups towards electrophiles.

The chemical foundation of the alteration of the DNA structure by β-haloalkylamines is based on the formation of cross-covalent bonds with a guanine residue in each of the DNA strands, producing the corresponding distortion

Nitrogen Mustard Action Mechanism

Military Designations for Nitrogen Mustards

HN-1 was originally designed to kill warts, but was later identified as a potential chemical warfare agent.

HN-2 was designed as a military agent but was later used in the treatment of cancer. Today it has been superseded by other agents for the treatment of cancer.

HN-3 was designed solely as a military agent.

Forms of poisoning

*Because it is heavier than air, vapor from nitrogen mustard settles in low-lying areas.

Table 1: routes of intoxication depending on the environment by nitrogenous mustards.

Signs and symptoms

Potential short-term health effects

The health effects of nitrogen mustards depend on how much people are exposed to, how, and how long they are exposed.

Signs and symptoms of exposure usually do not occur immediately. Depending on the severity of exposure, symptoms may appear after several hours.

They can produce the following effects on specific parts of the body:

• Skin: redness followed by blisters at 6-12 hours.

• Eyes: irritation, pain, swelling, and tears may appear and at high concentrations may cause burns and blindness.
• Respiratory tract: sinus pain, cough, sore throat and shortness of breath.
• Digestive pain: abdominal pain, diarrhea, nausea and vomiting.
• Brain: tremors, lack of coordination and seizures after a long exhibition.

The presence of these signs and symptoms does not necessarily indicate that a person has been exposed to nitrogen mustard.

Potential long-term health effects

Exposure to nitrogenous mustard can cause:

• If they are in liquid form, percutaneously, second and third grade burns and scarring.
• In the form of steam, by inhalation, chronic respiratory disease and by eye, eye problems.

From the third/fifth day, symptoms of bone marrow suppression may appear, leading to anemia, bleeding and an increased risk of infection. In the most serious situations, they could cause death.

Cancer has also been observed in animals after prolonged or repeated exposure and there is evidence that they cause leukemia in humans.

Protocol for action in case of exposure

1. Abandon the release zone of the toxic (if it occurs in a closed space leave it and if it occurs at the environmental level to go to higher altitude zones). It is convenient to go to a fresh air zone to reduce the possibility of death.
2. Communicate the toxicological emergency coordinators to ensure effective evacuation.
3. If you are suspected of having been exposed, it is convenient to remove your clothes (preferably by cutting the garments), wash your entire body quickly with soap and soap and seek medical attention as soon as possible.
4. If you have blurred vision or scozor in your eyes, rinse them with water for 10-15 minutes.
5. Contact lenses should be disposed of along with contaminated clothing and in case of wearing glasses cleaned with soap and water.
6. Introduce in a plastic bag the disposable products with the help of rubber gloves or tweezers. Then seal the bag, place it in another bag and deliver it to the Department of Local or State Emergency Health.
7. In case of toxic intake, vomiting should not be caused or drinking any liquid.

Antidote

There is no antidote for this exposure. Treatment consists of eliminating the poison from the body as quickly as possible and guaranteeing medical attention.