Chloroform

Acute effects: Inhalation of high concentrations of chloroform can cause depression of the central and peripheral nervous systems, damage to the liver and kidneys and cardiac sensitization to catecholamines. When it was used as an anaesthetic, hepatotoxicity, nephrotoxicity and cardiovascular derangement (including arrythmias and hypotension) were observed. Nausea and vomiting, decreased intestinal tone and motility, and decrease of urine flow were also described during recovery. In general, inhalation of high levels of chloroform results in fatigue, dizziness and headaches. Poisoning by ingestion has similar symptoms, as well as causing irritation of the mucosa lining the mouth, esophagus and stomach. Application directly to the skin can produce burning sensations and sores.

Chronic effects: Long-term exposure can cause liver and kidney damage. Symptoms of chronic exposure include: fatigue, dull-wittedness, depression, gastrointestinal distress and frequent and burning micturition. Chloroform was listed by the Canadian Ministers of Health and Environment on the second Priority Substances List (PSL2), identifying it as a substance in need of assessment for its potential to be "toxic" under the definitions of the Canadian Environmental Protection Act.

Carcinogenicity: Chloroform causes liver and kidney tumours and cholangiocarcinomas in rodents. The mechanism for this carcinogenicity is, however, not known. Epidemiological studies have found a possible relationship between chlorinated drinking water and cancer of the colon and urinary bladder, but these tests have not demonstrated a direct link between cancer and chloroform itself. Chloroform is classified as a Group B2 (probable human carcinogen) by the US EPA and as a Group 2B (possible human carcinogen) by the International Agency for Research on Cancer (IARC).

Sensitive populations: Populations that may be more sensitive to chloroform include those with liver, kidney or central nervous system diseases. Chronic alcoholics are also at greater risk as the effects of chloroform on the liver and kidneys are increased by interactions with alcohol.

Quick reference index

Chemical formula and synonyms -- CHCl3; trichloromethane, methyl trichloride, methane trichloride, methenyl chloride, methenyl trichloride, trichloroform, formyl trichloride, TCM, Freon 20.

Use -- Chloroform is used as a solvent in pharmaceutical manufacturing, as a general reagent in laboratories, in the production of fluorocarbon 22 (which is used primarily as a refrigerant), as an aerosol propellant and as a pesticide in grain fumigation.

Physico-chemical properties -- Chloroform is a clear, colorless, volatile liquid. It has a pleasant odor with a slightly sweet taste. It is nonflammable and, under standard atmospheric conditions, does not form explosive mixtures. It is miscible with most organic solvents and slightly soluble in water.

Environmental fate -- When chloroform is released into soil or water, most of it is lost to the atmosphere by evaporation. Almost all of the remaining chloroform released into the soil tends to drain down to the groundwater. It is very persistent in both water and in air, where it lasts for 150 to 230 days. In the troposphere, chloroform is photochemically degraded via the reaction with hydroxyl radicals. The breakdown products it forms in the atmosphere are phosgene and hydrogen chloride, both of which are toxic. Although chloroform doesn't seem to accumulate in plants or animals, small amounts of it are found in some foods.

Sources -- Chloroform is directly released by emissions from the manufacture of pharmaceuticals and fluorocarbon 22 refrigerants and fluoropolymers, from laboratory use and from grain fumigation. The largest source of chloroform is its release as a by-product from the chlorination of water. Other indirect sources include: bleaching at pulp and paper mills, household cleaning and laundry bleach, cooling towers and air stripping towers.

Exposure -- Inhalation, ingestion or dermal absorption. The primary route is ingestion with chlorinated water. Due to its volatility, inhalation is a common route of exposure, especially in the workplace.

SET_EDITION

Useful regulatory information

EnvironmentDrinking Water MAC0.1 mg/L

ACGIHThreshold Limit Value - Time Weighted Average (TLV-TWA) (8-Hr. workshift)10 ppm

NIOSHRecommended Exposure Limit - Short Term Exposure Limit (STEL) (60 min)2 ppm

Immediately Dangerous to Life and Health1000 ppm

OSHAPermissible Exposure Limit - Time Weighted Average

(PEL-TWA) (8-Hr. workshift)50 ppm

Permissible Exposure Limit - Ceiling Limit (PEL-CLG)240 mg/m3