2,4,6Trichlorophenol [factsheet]

2,4,6-TRICHLOROPHENOL

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. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Very low levels of 2,4,6-trichlorophenol have been detected in air, with levels generally less than 0.001 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 Information

Acute Effects:

* No studies are available on the acute (short-term) effects of 2,4,6-trichlorophenol in humans via inhalation or oral exposure. (1)

* Tests involving acute exposure of animals, such as the LD₅₀ test in rats, have shown 2,4,6-trichlorophenol to have moderate acute toxicity. (2)

Chronic Effects (Noncancer):

* The only available chronic (long-term) 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 and liver 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 determined that there are inadequate data to establish an RfC for 2,4,6-trichlorophenol. (3)

* EPA has not established an RfD for 2,4,6-trichlorophenol. (3)

Reproductive/Developmental Effects:

* 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)

Cancer Risk:

* 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 produces leukemia and liver cancer. (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 H 10^-6 (m g/m³)^-1. EPA estimates that, if an individual were to breathe air containing 2,4,6-trichlorophenol at 0.3 Fg/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 Fg/m³ would result in not greater than a one-in-hundred thousand increased chance of developing cancer, and air containing 30.0 Fg/m³ would result in not greater than a one-in-ten-thousand increased chance of developing cancer. (3)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has ranked 2,4,6-trichlorophenol in the nonthreshold category. The 1/ED₁₀ value is 0.09 per (mg/kg)/d and this would place it in the low category under Superfund's ranking for carcinogenic hazard. (4)

Physical Properties

* 2,4,6-Trichlorophenol is a yellow solid with a strong, sweet smell. (1)

* The odor threshold for 2,4,6-trichlorophenol is 0.0026 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 EC, and it has a log octanol/water partition coefficient (Log K_ow) of 3.38. (1)

Uses

* 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. Production of 2,4,6-trichlorophenol was discontinued in the United States in the 1980s.

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
10.0
_ _ _ _ 1.0
_ _ _ _ 0.1
_ _ _ _ 0.01
_ _ _ _ 0.001
_ _ _ _ 0.0001	* EPA Cancer Risk Level^c (1-in-a-million excess lifetime risk) = 0.0003 mg/m³		3

^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.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 2,4,6-Trichlorophenol (Draft). U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1989.

2. 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.

3. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 2,4,6-Trichlorophenol. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

4. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.