Mustard gas, also known as sulfur mustard, is a chemical warfare agent first used in World War I. It is classified as a vesicant, causing severe blistering of the skin and mucous membranes upon contact. This agent caused widespread casualties in conflicts, including the Iran-Iraq War. It can spread over large areas and persist for days.
How Mustard Gas Harms Cells
Mustard gas damages cells as an alkylating agent, chemically modifying DNA and proteins by adding alkyl groups. This alteration interferes with cellular processes like DNA replication and repair. Damaged DNA causes cells to struggle with division and function, leading to dysfunction and cell death.
The damage can overwhelm a cell’s natural repair mechanisms, including DNA damage response pathways. While cells try to repair genetic damage, excessive modification can lead to single and double-strand breaks in DNA. This cellular disruption contributes to the delayed onset of symptoms, which may not appear for several hours or even a full day after exposure.
Effects on Skin and Eyes
Exposure to mustard gas affects the skin, with symptoms appearing hours after contact. Individuals may first experience itching and irritation, followed by redness and swelling. Within 2 to 48 hours, large, painful blisters filled with fluid can form. These blisters can merge, resembling chemical burns, and may be as severe as second or third-degree burns.
Skin damage is often pronounced in areas rich in sweat and sebaceous glands, such as the face, armpits, and groin. If blisters rupture, they create open wounds susceptible to secondary infections, prolonging healing. Long-term skin effects include scarring, changes in pigmentation, and an increased risk of skin cancer.
The eyes are sensitive to mustard gas vapor and liquid. Initial symptoms, appearing within minutes to a few hours, include irritation, pain, tearing, and a gritty sensation. Eyelids may swell, and conjunctivitis, or “pink eye,” is common. Severe exposure can lead to corneal damage, including swelling, ulcers, and scarring. These injuries can result in temporary blindness, and in severe cases, persistent vision impairment or permanent blindness.
Impact on the Respiratory System
Inhaling mustard gas damages the respiratory tract, with symptoms often delayed for several hours. Initial effects include irritation of the nose, throat, and lungs, leading to coughing, hoarseness, and difficulty breathing.
As damage progresses, more severe conditions develop. These include bronchitis, an inflammation of the bronchial tubes, and pneumonia, an infection that inflames the air sacs. Pulmonary edema, where fluid accumulates in the lungs, can also occur, making breathing difficult. In some cases, fibrin casts can obstruct airways, leading to acute respiratory failure. Pulmonary injury is a leading cause of death in the days to weeks following severe inhalation.
Systemic and Long-Term Health Consequences
Beyond localized effects on the skin, eyes, and respiratory system, mustard gas can cause systemic effects and chronic health problems. Acute systemic effects include gastrointestinal issues like nausea, vomiting, and diarrhea. Bone marrow suppression is another systemic effect, reducing white blood cell production and increasing susceptibility to infections. This can lead to leukopenia, compromising the immune system.
Long-term exposure increases the risk of various cancers, including lung, skin, pharynx, and larynx cancers. Chronic respiratory diseases are common complications, such as persistent bronchitis, emphysema, and deteriorating lung function. Many survivors experience ongoing shortness of breath and chronic cough years after exposure.
Persistent eye problems are also reported, including chronic conjunctivitis, corneal opacities, and keratitis that can impair vision. Individuals exposed to mustard gas may also experience long-term psychological effects, such as post-traumatic stress disorder (PTSD), affecting their quality of life.