Because it is a liquid that does not bind well to soil, methylene chloride that makes its way into the ground can move through the ground and enter groundwater. Plants and animals are not likely to store methylene chloride. Effects of methylene chloride on human health and the environment depend on how much methylene chloride is present and the length and frequency of exposure. Effects also depend on the health of a person or the condition of the environment when exposure occurs. Breathing large amounts of methylene chloride for short periods of time adversely affects the human nervous system and the heart.
Effects range from unsteadiness and numbness in fingers and toes to unconsciousness and death.
The heart has to work harder, and the blood carries less oxygen as the body breaks methylene chloride down to carbon monoxide. Direct contact with methylene chloride liquid or vapor irritates the skin and the eyes. These effects are not likely to occur at levels of methylene chloride that are normally found in the environment. Human health effects associated with breathing or otherwise consuming smaller amounts of methylene chloride over long periods of time are not known. Laboratory studies show that repeat exposure to methylene chloride causes kidney and liver damage and cancer in animals that breathe air or drink water contaminated with the chemical.