OSHA "select carcinogen"; highly irritating to the eyes, skin, and respiratory tract.

The acute toxicity of chloromethyl methyl ether is moderate to high. Inhalation of the vapor is severely irritating to the eyes, skin, nose, and respiratory tract, and causes sore throat, fever, chills, and difficulty breathing. Exposure to high concentrations can lead to delayed pulmonary edema, which can be fatal. Eye or skin contact with the liquid can result in severe and painful burns. Ingestion of this substance may lead to severe burns of the mouth and stomach and can be fatal.

Chloromethyl methyl ether is regulated by OSHA as a carcinogen (29 CFR 1910.1006) and is listed in IARC Group 1 ("carcinogenic to humans"). This substance is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard. Note also that some commercial samples of chloromethyl methyl ether contain up to 7% of highly carcinogenic bis(chloromethyl) ether. Hydrolysis of chloromethyl methyl ether produces HCl and formaldehyde, which can recombine to form bis(chloromethyl) ether. No information is available on the reproductive and developmental toxicity of chloromethyl methyl ether. Odor does not provide adequate warning of the harmful presence of this carcinogenic substance.

Chloromethyl methyl ether is highly flammable. Fires involving this substance should be extinguished with carbon dioxide or dry chemical extinguishers.