Hazard Summary-Created in April 1992; Revised in January 2000
2,4,6-Trichlorophenol is no longer used in the United States and only
very low levels have been detected in ambient air. Limited information
is available on the acute (short-term) and chronic (long-term) effects
of 2,4,6-trichlorophenol in humans. The only available human study
reported respiratory effects, such as cough, chronic bronchitis, chest
wheezing, altered pulmonary function, and pulmonary lesions from chronic
exposure to 2,4,6-trichlorophenol via inhalation. There are no studies
available on the reproductive, developmental, or carcinogenic effects
of 2,4,6-trichlorophenol in humans. 2,4,6-Trichlorophenol has been
shown to be carcinogenic in animals, producing lymphomas, leukemia, and
liver cancer via oral exposure. EPA has classified 2,4,6-trichlorophenol
as a Group B2, probable human carcinogen.
Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS), which contains information on the carcinogenic effects of 2,4,6-trichlorophenol including the unit cancer risk for inhalation exposure, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for 2,4,6-Trichlorophenol.
- 2,4,6-Trichlorophenol is no longer used in the United States. It was previously used as an antiseptic; a pesticide for wood, leather, and glue preservation; and as an anti-mildew treatment. It was also used in the manufacture of other chemicals. (1)
- Production of 2,4,6-trichlorophenol was discontinued in the United States in the 1980s. (1)
Sources and Potential Exposure
- Very low levels of 2,4,6-trichlorophenol have been detected in air, with levels generally less than 0.001 parts per billion (ppb). (1)
- 2,4,6-Trichlorophenol exposure may occur through drinking water or food. (1)
- Exposure to 2,4,6-trichlorophenol may occur through its use in pesticides, or wood, leather, or glue preservatives which were produced before 2,4,6-trichlorophenol production was discontinued in the 1980s. (1)
Assessing Personal Exposure
- A test is available that can measure the amount of 2,4,6-trichlorophenol in the blood. (1)
Health Hazard InformationAcute Effects:
- No studies are available on the acute effects of 2,4,6-trichlorophenol in humans via inhalation or oral exposure. (1)
- Tests involving acute exposure of rats have shown 2,4,6-trichlorophenol to have moderate acute toxicity. (2)
- The only available chronic inhalation study in humans reported that occupational exposure to 2,4,6-trichlorophenol was associated with respiratory effects such as cough, chronic bronchitis, chest wheezing, altered pulmonary function, and pulmonary lesions. (1)
- Animal studies have reported effects on the blood (increased splenic hematopoesis) and liver (midzonal vacuolization of hepatocytes and hepatic hyperplasia) from chronic oral exposure to 2,4,6-trichlorophenol, while no effects on the cardiovascular system, gastrointestinal system, kidneys, skin, immune system, or central nervous system were reported in these studies. (1)
- EPA has not established a Reference Concentration (RfC) or Reference Dose (RfD) for 2,4,6-trichlorophenol. (3)
- No studies are available on the developmental or reproductive effects of 2,4,6-trichlorophenol in humans from inhalation or oral exposure. (1)
- Animal studies have reported a transient reduction in the body weight of the offspring of rats exposed to 2,4,6-trichlorophenol orally, while no other developmental effects have been noted in animal studies. (1)
- Reduced mean litter size was observed in rats following maternal exposure to 2,4,6-trichlorophenol in the drinking water, while no reproductive effects were observed in other animal studies via gavage (placing the chemical experimentally in the stomach). (1)
- No studies are available on the carcinogenic effects of 2,4,6-trichlorophenol in humans from inhalation or oral exposure. (1,3)
- Oral exposure to 2,4,6-trichlorophenol in rats and mice resulted in an increased incidence of lymphomas or leukemias and hepatocellular adenomas or carcinomas. (1,3)
- EPA has classified 2,4,6-trichlorophenol as a Group B2, probable human carcinogen. (3)
- EPA uses mathematical models, based on animal studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA calculated an inhalation unit risk estimate of 3.1 × 10-6 (µg/m3)-1. EPA estimates that, if an individual were to continuously breathe air containing 2,4,6-trichlorophenol at an average of 0.3 µg/m3 (3 x 10-4 mg/m3) over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA estimates that breathing air containing 3.0 µg/m3 (3 x 10-3 mg/m3) would result in not greater than a one-in-hundred thousand increased chance of developing cancer, and air containing 30.0 µg/m3 (3 x 10-2 mg/m3) would result in not greater than a one-in-ten-thousand increased chance of developing cancer. For a detailed discussion of confidence in the potency estimates, please see IRIS. (3)
- EPA has also calculated an oral unit risk factor of 3.1 x 10-7 (µg/L)-1 and an oral cancer slope factor of 0.011 (mg/kg/day)-1. (3)
- 2,4,6-Trichlorophenol is a yellow solid or flakes with a strong, sweet smell. (1)
- The odor threshold for 2,4,6-trichlorophenol is 0.0026 parts per million (ppm). (1)
- The chemical formula for 2,4,6-trichlorophenol is C6H3Cl3O, and its molecular weight is 197.46 g/mol. (1)
- The vapor pressure for 2,4,6-trichlorophenol is 0.012 mm Hg at 25 °C, and it has a log octanol/water partition coefficient (log Kow) of 3.38. (1)
To convert concentrations in air (at 25 °C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For 2,4,6-trichlorophenol: 1 ppm = 8.1 mg/m3. To convert concentrations in air from µg/m3 to mg/m3: mg/m3 = (µg/m3) × (1 mg/1,000 µg).
Health Data from Inhalation Exposure
The health values cited in this factsheet were obtained in December 1999.
a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.
b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.
c These cancer risk estimates were derived from oral data and converted to provide the estimated inhalation risk.
- Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 2,4,6-Trichlorophenol. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1990.
- U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
- U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 2,4,6-Trichlorophenol. National Center for Environmental Assessment, Office of Research and Development, Washington, DC. 1999.