What Is Chloroform?

ATSDR describes chloroform as a colorless liquid with a pleasant, nonirritating odor and a slightly sweet taste that occurs naturally, mainly in wet environments, can be formed in small amounts when chlorine is added to water, and is also man-made. It says chloroform was used in the past as an inhaled anesthetic during surgery but no longer is because safer alternatives are available, and that it is now used as a solvent and to make other chemicals.

It can come from tap water. ATSDR says that if your home water supply is treated with chlorine, household activities such as showering, bathing, washing clothes or dishes, or preparing food may expose you to chloroform. Federal drinking water rules at 40 CFR 141.64 include a disinfection byproduct limit of 0.080 mg/L for total trihalomethanes, complied with as a locational running annual average at each monitoring location.

ATSDR says breathing low to moderate levels of chloroform for a short time can cause dizziness, tiredness or headache, that at high levels people may have trouble breathing and pass out, and that breathing or drinking large amounts can cause severe liver and kidney damage and, at very high levels, death. It reports that the US Department of Health and Human Services has determined chloroform is reasonably anticipated to be a human carcinogen based on animal evidence, and that the EPA classified it as likely to be carcinogenic to humans at high doses that cause cell damage but not likely at lower doses that do not. For workplaces, the NIOSH Pocket Guide lists a recommended short-term limit of 2 ppm over 60 minutes and an OSHA ceiling limit of 50 ppm.