Methyl Iodide is a colorless liquid that turns brown on exposure to light. Denser than water. Contact may irritate skin, eyes and mucous membranes. Very toxic by ingestion, inhalation and skin absorption. Methyl iodide is used as an intermediate in the manufacture of some pharmaceuticals and pesticides, in methylation processes, and in the field of microscopy. In humans, acute (short-term) exposure to methyl iodide by inhalation may depress the central nervous system (CNS), irritate the lungs and skin, and affect the kidneys. Massive acute inhalation exposure to methyl iodide has led to pulmonary edema. Acute inhalation exposure of humans to methyl iodide has resulted in nausea, vomiting, vertigo, ataxia, slurred speech, drowsiness, skin blistering, and eye irritation. Chronic (long-term) exposure of humans to methyl iodide by inhalation may affect the CNS and cause skin burns. EPA has not classified methyl iodide for potential carcinogenicity.