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Trifluralin. Hazard Summary prepared by the Office of Air Quality Planning & Standards. US EPA.
From: http://www.epa.gov/ttn/uatw/hlthef/trifural.html
1582-09-8
Hazard Summary
CAUTION: Unless otherwise noted, the quantitative information on these fact sheets are from "EPA Health Effects Notebook for Hazardous Air Pollutants-Draft", EPA-452/D-95-00, PB95-503579, December 1994." Please conduct a current literature search and check the appropriate current online database for the most recent quantitative information.
- No information is available on the acute (short-term), chronic (long-term), reproductive or developmental, and carcinogenic effects of trifluralin in humans.
- Acute animal tests have demonstrated trifluralin to have moderate acute toxicity by inhalation and low to moderate acute toxicity by oral or dermal exposure.
- Decreased weight gain, changes in hematological parameters, and increased liver weight were observed in dogs chronically exposed to trifluralin in their diet.
- The U.S. Environmental Protection Agency (EPA) has not established a Reference Concentration (RfC) for trifluralin.
- The Reference Dose (RfD) for trifluralin is 0.0075 mg/kg/d.a EPA estimates that consumption of this dose or less over a lifetime would not likely result in the occurrence of chronic noncancer effects.b
- Skeletal abnormalities were observed in the offspring of mice exposed via gavage (experimentally placing the chemical in the stomach). In rats and rabbits exposed via gavage, depressed fetal weight was observed. Fetotoxic and teratogenic effects have been observed in other rodent studies.
- Increased incidences of urinary tract tumors and thyroid tumors were observed in rats exposed to trifluralin in their diet. Trifluralin did not produce statistically significant increases in tumors in other studies. EPA has classified trifluralin as a Group C, possible human carcinogen (cancer-causing agent) of low carcinogenic hazard, with a 1/ED10 value of 0.037 per (mg/kg)dc and an oral unit risk estimate of 2.2 x 10-7 (g/L)-1.
a Milligrams per kilogram per day is one way to measure the amount of the contaminant that is consumed in food.
b The RfD is not a direct estimator of risk but rather a reference point to gauge the potential effects. Exceedance of the RfD does not imply that an adverse health effect would necessarily occur. As the amount and frequency of exposures exceeding the RfD increase, the probability of adverse health effects also increases.
c The 1/ED10 value is a measure of the carcinogenic potency of a chemical. The value reported here has been proposed in the hazard ranking of hazardous air pollutants in EPA's proposed rulemaking (Section 112(g) of the Clean Air Act, April 1994).Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS), which contains information on oral chronic toxicity and the RfD, and the carcinogenic effects of trifluralin including the unit cancer risk for oral exposure, and EPA's Health and Environmental Effects Profile for Trifluralin. 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
- Occupational exposure to trifluralin may occur by inhalation or dermal contact during its production, formulation, or application as a herbicide. Dermal exposure by farmworkers may also occur long after initial exposure, as it has been found to be adsorbed to clothing even after numerous washings. (1)
- Trifluralin may be released to the environment in fugitive emissions during its production and in wastewater effluent. It is also released to the ambient environment during its application as a herbicide and may be released to surface water as a result of agricultural runoff. (1)
- The general population may be exposed to trifluralin by dermal and inhalation exposure from lawn products and by ingestion of contaminated agricultural products or the ingestion of fish caught in contaminated waters. (1)
Assessing Personal Exposure
- No information was located regarding the measurement of personal exposure to trifluralin.
Health Hazard Information
Acute Effects:
- Information is not available on the effects of acute (short-term) exposure of humans to trifluralin.
- Acute animal tests, such as the LC50 and LD50 tests in rats, mice, and rabbits, have demonstrated trifluralin to have moderate acute toxicity by inhalation and low to moderate acute toxicity by oral or dermal exposure. (2)
Chronic Effects (Noncancer):
- No information is available on the chronic (long-term) effects of trifluralin in humans.
- Decreased weight gain, changes in hematological parameters, and increased liver weight were observed in dogs chronically exposed to trifluralin in their diet. (3)
- EPA has not established an RfC for trifluralin. (3)
- The RfD for trifluralin is 0.0075 mg/kg/d based on increased liver weights and an increase in methemoglobinemia in dogs. (3)
- EPA has high confidence in the study on which the RfD is based because it is of good quality; high confidence in the database because additional studies are supportive and of good quality; and, consequently, high confidence in the RfD. (3)
Reproductive/Developmental Effects:
- No information is available on the reproductive or developmental effects of trifluralin in humans.
- Skeletal abnormalities were observed in the offspring of mice exposed via gavage (experimentally placing the chemical in the stomach). (4)
- In rats and rabbits exposed via gavage, depressed fetal weight was observed. (1)
- Fetotoxic and teratogenic effects have been observed in other rodent studies. (3)
Cancer Risk:
- No information is available on the carcinogenic effects of trifluralin in humans. (3)
- Increased incidences of urinary tract tumors and thyroid tumors were observed in rats exposed to trifluralin in their diet. Trifluralin did not produce statistically significant increases in tumors in four other rodent studies. (3)
- Trifluralin is structurally similar to ethalfluralin, a carcinogen in the rat; both compounds produce a common urinary metabolite in rats that produces nonneoplastic renal pathology. (3)
- N-Nitroso-di-n-propylamine (NDPA), an unavoidable contaminant in trifluralin-containing products, has been found to be carcinogenic in rodents. (4)
- EPA has classified trifluralin as a Group C, possible human carcinogen. (3)
- EPA uses mathematical models, based on human and animal studies, to estimate the probability of a person developing cancer from drinking water containing a specified concentration of a chemical. EPA calculated an oral unit risk estimate of 2.2 x 10-7 (g/L)-1. EPA estimates that, if an individual were to drink water containing trifluralin at 5.0 µg/L(1) 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 drinking water containing this chemical. Similarly, EPA estimates that drinking water containing 50.0 µg/L would likely result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and water containing 500.0 µg/L 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 trifluralin in the nonthreshold category. The 1/ED10 value is 0.037 per (mg/kg)/d and this would place it in the low category under Superfund's ranking for carcinogenic hazard. (5)
Physical Properties
- The chemical formula for trifluralin is C13H16F3N3O4, and its molecular weight is 335.3 g/mol. (4)
- Trifluralin occurs as a yellow-orange crystalline solid or crystals that are slightly soluble in water. (4,6,7)
- The odor threshold has not been established.
- The vapor pressure for trifluralin is 1.99 x 10-4 mm Hg at 29.5 C, and the log octanol/water partition coefficient (log Kow) is reported to be 5.3. (4)
Uses
- Trifluralin is a herbicide used to control annual grasses and some broadleaf annual weeds on a variety of crops, shrubs, and flowers. It is used mostly on cotton, as well as on soybeans and some fruits and vegetables. (4)
Conversion Factors:
To convert from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For trifluralin: 1 ppm = 13.71 mg/m3.Health Data from Oral Exposure
Concentration
(mg/kg/d) |
Health
numbersa |
Regulatory,
advisory numbersb |
Reference |
10,000.0 |
|
2 | |
-- -- -- -- 1,000.0 |
|
2
2 |
|
-- -- -- -- 100.0 |
|||
-- -- -- -- 10.0 |
|||
-- -- -- -- 1.0 |
|
3 | |
-- -- -- -- 0.1 |
|
3 | |
-- -- -- -- 0.01 |
|||
-- -- -- -- 0.001 |
|
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 The LOAEL and NOAEL are from the critical study used as the basis for the EPA RfD.References
- U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
- 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 Trifluraline. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.
- U.S. Environmental Protection Agency. Health and Environmental Effects Profile for Trifluraline. EPA/600/x-84/234. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1984.
- U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air Act--Section 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPA450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.
- The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.
- M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.
1. *Micrograms per liter is the unit of measurement for chemicals in water.
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