• What are the main health hazards associated with breathing in methane?
• What happens when methane comes into contact with my skin?
• Can methane hurt my eyes?
• What happens if methane is accidentally swallowed (enters the digestive system)?
• What are the long-term health effects of exposure to methane?
• Will methane cause cancer?
• Will methane cause any problems with my reproductive system?
• Will methane cause effects on the fetus/unborn baby?
• Will methane act in a synergistic manner with other materials (will its effects be more than the sum of the effects from the exposure to each chemical alone)?
• Is there potential for methane to build-up or accumulate in my body?

What are the main health hazards associated with breathing in methane?

Methane is not toxic below the lower explosive limit of 5% (50000 ppm). However, when methane is present at high concentrations, it acts as an asphyxiant. Asphyxiants displace oxygen in the air and can cause symptoms of oxygen deprivation (asphyxiation). The available oxygen should be a minimum of 18% or harmful effects will result. Methane displaces oxygen to 18% in air when present at 14% (140000 ppm). It is not expected to cause unconsciousness (narcosis) due to central nervous system depression until it reaches much higher concentrations (30% or 300000 ppm) - well above the lower explosive limit and asphyxiating concentrations.

Effects of oxygen deficiency are:

12-16% - breathing and pulse rate are increased, with slight muscular incoordination;

10-14% - emotional upsets, abnormal fatigue from exertion, disturbed respiration;

6-10% - nausea and vomiting, inability to move freely, collapse, possible lack of consciousness;

below 6% - convulsive movements, gasping, possible respiratory collapse and death.

Since exercise increases the body's need for oxygen, symptoms will occur more quickly during exertion in an oxygen-deficient environment. Survivors of oxygen deprivation may show damage to some or all organs including the central nervous system and the brain. These effects may or may not be reversible with time, depending on the degree and duration of the low oxygen and the amount of tissue injury.

Some closely related aliphatic hydrocarbons (propane, butane and isobutane) may be weak cardiac sensitizers in humans following inhalation exposures to high concentrations (greater than 5% for isobutane and greater than 10% for propane). Cardiac sensitizers may cause the sudden onset of an irregular heartbeat (arrhythmia) and, in some cases, sudden death. Sudden deaths have been reported in cases of substance abuse involving butane and propane. Under stressful conditions and with exposure to high concentrations, the effects of cardiac sensitization may be important for some hydrocarbon gases. The asphyxiant effects of methane may enhance cardiac sensitization.

What happens when methane comes into contact with my skin?

Methane gas is not a skin irritant.

Contact with the refrigerated liquefied gas or compressed gas escaping from its cylinder may cause cold burns or frostbite. Symptoms of mild frostbite include numbness, prickling and itching in the affected area. Symptoms of more severe frostbite include a burning sensation and stiffness of the affected area. The skin may become waxy white or yellow. Blistering, tissue death and gangrene may also develop in severe cases.

Can methane hurt my eyes?

Methane gas does not irritate the eyes.

Contact with the refrigerated liquefied gas or compressed gas escaping from its cylinder may cause cold burns or freezing of the eye. Permanent eye damage or blindness could result.

What happens if methane is accidentally swallowed (enters the digestive system)?

Not applicable to gases.

What are the long-term health effects of exposure to methane?

No human or animal information was located. Harmful effects are not expected following long-term exposure.

Will methane cause cancer?

No human or animal information was located. Methane is not expected to cause cancer.

Will methane cause any problems with my reproductive system?

No human or animal information was located. Methane is not expected to cause reproductive toxicity.

Will methane cause effects on the fetus/unborn baby?

No human information was located. No conclusions can be drawn based on the one limited animal study located.

Will methane act in a synergistic manner with other materials (will its effects be more than the sum of the effects from the exposure to each chemical alone)?

No information was located.

Is there potential for methane to build-up or accumulate in my body?

Methane does not accumulate.

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Document last updated on December 11, 2006

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