What Are the Effects of Long Exposure to Methane Gas in Humans & Animals?

Methane gas is an odorless, colorless flammable gas used to create light and heat. Natural decay, including the decay in landfills, sewers and marshes, releases methane gas; however, it evaporates quickly in these situations. Commercial energy companies mix methane gas with hydrogen sulfide so that it smells like rotten eggs when there is a leak. Methane can also create pockets underground, where it can stay for years.

Breathing

• Methane gas reduces the amount of oxygen in the air. Methane exposure causes loss of consciousness and depression of the central nervous system in both animals and humans. Long-term exposure can cause suffocation. If the oxygen level drops to 12 to 16 percent, pulse rate and breathing increase while muscular control decreases. As oxygen levels lower, you can experience emotional upset, fatigue, nausea, gasping, convulsions or death. Exercise accelerates the effects of methane exposure.

Skin and Eye Contact

• Methane gas itself does not affect the skin. Liquid methane, however, can cause frostbite on skin. The skin will be itchy, numb or prickly, and may burn or become stiff, if frostbite occurs. Blistering and gangrene occur in severe cases. Eyes are also not irritated by methane gas, but liquefied methane can freeze or cold-burn the eyes, causing permanent damage or blindness.

Ingestion

• Because it evaporates quickly, methane is not ingested, but very small amounts of methane can be found in food or drinking water. It is important that people wash their hands after handling methane and before eating and drinking. Cardiac sensitization and arrhythmia may occur under high concentrations of methane. Because methane is quickly eliminated from the body, however, it is difficult to test for the level of exposure.

Effects on Animals

• Animals exposed to 70 percent methane in air died within 18 minutes in a study by Forney and Harger in 1972. Animals exposed to 50 to 90 percent methane in oxygen experienced only decreased muscle control and mild depression. Animals showed no long-term effects after the methane exposure was eliminated.