Toxicity Profiles

RAGs A Format for Carbon Tetrachloride - CAS Number 56235

Carbon tetrachloride is a clear liquid with a sweet smell that can be detected at low levels. It is a manufactured organic compound that does not occur naturally; trade names include Benzinoform, Freon 10, Halon 104, Tetraform, or Tetrasol. Carbon tetrachloride is most often found as a colorless gas. It's not flammable and doesn't dissolve in water very easily. It was used in the production of refrigeration fluid and propellants for aerosol cans, as a pesticide, as a cleaning fluid and degreasing agent, in fire extinguishers, and in spot removers. Because of its harmful effects, these uses are now banned and it is only used in some industrial applications. It can form explosive, impact-sensitive mixtures with particulates of metals including aluminum, barium, beryllium, potassium, lithium, sodium and zinc. Carbon tetrachloride also forms explosive mixtures with chlorine trifluoride, calcium hypochlorite, calcium disilicide, triethyldialuminum trichloride, decaborane and dinitrogen tetraoxide. It will react violently with fluorine, boranes, allyl alcohol and other related chemicals.

High exposure to carbon tetrachloride by oral, inhalation, or dermal routes can cause liver, kidney, and central nervous system damage. The liver is especially sensitive to carbon tetrachloride because it swells and cells are damaged or destroyed. Kidneys are also damaged, causing a buildup of wastes in the blood. If exposure is low and then stops, the liver and kidneys can repair the damaged cells and function normally again. If exposure is very high, the nervous system, including the brain, is affected. Humans may feel intoxicated and experience headaches, dizziness, sleepiness, and nausea and vomiting. These effects may subside if exposure is stopped, but in severe cases, coma and even death can occur. Although an inhalation exposure of about 1000 ppm for a few minutes to hours will cause the narcotic effects in 100% of the population, large variations in sensitivity are seen. Alcohol intake greatly increases human sensitivity to carbon tetrachloride; consequently, exposure to 250 ppm for 15 minutes can be life threatening to an alcoholic. Subchronic and chronic exposure to doses as low as 10 ppm can result in liver and kidney damage.

Although data for the carcinogenicity of carbon tetrachloride in humans are inconclusive, there is ample evidence in animals that the chemical can cause liver cancer. Hepatocellular carcinomas have been induced in hamsters, rats and mice after oral carbon tetrachloride treatment for 16 to 76 weeks. Liver tumors have also been demonstrated in rats following inhalation exposure, but the doses were not quantitatively established. The EPA weight-of-evidence classification for both oral and inhalation exposure is B2, probable human carcinogen based on adequate animal evidence.

The following is a presentation of the toxicity information associated with Carbon Tetrachloride.

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 7.00E-04 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 1000.
  • The Oral Chronic Reference Dose is based on the Bruckner et al. study from 1986.
  • The Oral Chronic Reference Dose study target organ is liver.
  • The Oral Chronic Reference Dose study critical effect is lesions.
  • The overall confidence in the Oral Chronic Reference Dose is medium.

  • The Dermal Chronic Reference Dose is 4.55E-04 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.6500.

Carcinogenic Health Effects

  • The Oral Slope Factor is 1.30E-01 (mg/kg-day)-1.
  • The Oral Slope Factor study target organ is liver.
  • The Oral Slope Factor study cancer type is carcinomas/hepatomas.
  • The Oral Slope Factor is based on the NCI study from 1977.

  • The Inhalation Unit Risk is 1.5E-02 (mg/m3)-1.
  • The Inhalation Unit Risk study target organ is liver.
  • The Inhalation Unit Risk study cancer type is carcinomas/hepatomas.
  • The Inhalation Unit Risk is based on the NCI study from 1977.

  • The Dermal Slope Factor is 2.00E-01 (mg/kg-day)-1.
  • The Dermal Slope Factor is based on a gastrointestinal absorption factor of 0.6500.