PMEP Home Page --> Pesticide Active Ingredient Information --> EXTOXNET: The Extension Toxicology Network --> Metiram to Propoxur --> Oxyfluorfen

E  X  T  O  X  N  E  T
Extension Toxicology Network

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Michigan State University, Oregon State University, and University of California at Davis. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

  Pesticide
Information
Profile
Oxyfluorfen

Publication Date: 9/93

TRADE OR OTHER NAMES

Some trade names include Goal, Koltar and RH-2915

REGULATORY STATUS

Products containing oxyfluorfen must bear the signal word "Warning" on the label (1).

INTRODUCTION

Oxyfluorfen is a selective pre and postemergent herbicide used to control certain annual broadleaf and grassy weeds in vegetables, fruit, cotton, es] ornamentals and on non-crop areas. It is a contact herbicide and light is required for it to affect target plants (4). It is available in emulsifiable concentrate and granular formulations (1).

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Oxyfluorfen is a moderately toxic by ingestion and slightly toxic by dermal absorption (2). Vapors may cause irritation of the nose, throat, skin and eyes, and other forms may cause irritation to skin and eyes (2).

The oral LD50 for technical oxyfluorfen in rats is 5,000 mg/kg and > 5,000 mg/kg in dogs (1, 2). The dermal LD50 on rabbits is > 10,000 mg/kg (1).

CHRONIC TOXICITY

Long-term exposure to oxyfluorfen may cause the same symptoms as short-term exposure (2). Effects on the liver have been observed in long-term feeding studies with rats, mice and dogs (2). In a 2-year feeding study with dogs, the NOEL was 100 ppm (2.5 mg/kg/day) (5).

Reproductive Effects

In a developmental study with rats given doses of 10, 100 or 1,000 mg/kg/day by gavage, lower implantation, higher resorption, and lower fetal survival was seen at the 1,000 mg/kg level. Toxic effects on the mothers were also seen at this dose (5).

The NOEL in a 3-generation reproduction study with rats was 10 ppm (0.5 mg/kg/day). At 100 ppm (5 mg/kg/day), there were decreased survival of fetuses and decreased maternal and fetal weights (5).

Teratogenic Effects

In a developmental study with rabbits, 30 mg/kg/day, the highest dose tested, produced an increase in fused sternal bones in the fetuses as well as toxic effects on the mothers. The NOEL was 10 mg/kg/day (5).

Mutagenic Effects

Mutagenicity tests have produced mixed results. Tests on rats, mice and on bacterial cell cultures and unscheduled DNA synthesis tests have been negative, while other tests on mice and bacterial cell cultures have been positive (5).

Carcinogenic Effects

In a 20-month study with mice fed 2, 20 or 200 ppm, doses above 2 ppm produced benign and malignant liver tumors in male mice. No tumors were formed in female mice (5). No carcinogenic effects were observed in a 2-year study with rats fed doses as high as 40 mg/kg and increased to 80 mg/kg after 57 weeks (5). EPA has classified oxyfluorfen as a possible human carcinogen because it caused tumor formation in one sex of one test species and because it was mutagenic in bacterial and mouse cell cultures (5).

Organ Toxicity

Effects on the liver have been observed in long term feeding studies of rats, mice and dogs (2).

Fate in Humans and Animals

Because oxyfluorfen is highly hydrophobic, it is expected to concentrate in the fatty tissues of animals (7).

ECOLOGICAL EFFECTS

Effects on Birds

The oral LD50 for technical oxyfluorfen in bobwhite quail is > 2,000 mg/kg and considered practically non-toxic. The dietary LC50 for oxyfluorfen in bobwhite quail is 390 ppm, and in mallard ducks is 4,000 ppm (7).

Dietary concentrations as high as 100 ppm had no effect on reproduction in mallards or bobwhite quail (7).

Effects on Aquatic Organisms

Oxyfluorfen is highly toxic to aquatic invertebrates, freshwater clams, oysters, aquatic plants and fish (4). Its acute LC50 in bluegill sunfish is 200 ppb, 410 ppb in rainbow trout, 400 ppb in channel catfish, 150 ppb in fathead minnow, 32 ppb in grass shrimp, and 32 ppb in oysters (7). Its 96- hour LC50 in freshwater clams is 10 ppm. The 96-hour LC50 for the product Goal 2E in Daphnia magna, a small freshwater crustacean, is 1.5 ppm (7).

Oxyfluorfen accumulated up to 13 ppm in bluegill sunfish exposed to 10 ppb for 40 days. This represents a bioconcentration factor (BCF) of 1,300. The BCF in channel catfish was 700 to 5,000 in one 30-day study (7).

Effects on Other Animals (Nontarget species)

No information was found.

ENVIRONMENTAL FATE

Breakdown of Chemical in Soil and Groundwater

Oxyfluorfen has a strong tendency to adsorb to soil particles and is nearly insoluble in water (3). Once oxyfluorfen is adsorbed to soil particles, it is not readily removed (4). It is therefore unlikely to leach downward or to contaminate groundwater. In aged sandy loam, 82% of applied oxyfluorfen remained in the top 2 inches of soil. Oxyfluorfen did not leach below 4 inches in any soil except sand (6).

In soils, oxyfluorfen is not subject to microbial degradation (4, 7), and is not subject to hydrolysis at pH 5, 7 or 9 (6). It is therefore highly resistant to degradation in the soil environment (7). Decomposition by light occurs slowly, with 15% of the oxyfluorfen applied to a soil surface degrading within 28 days (7). In laboratory studies, its soil half-life was 6 months (7). Its soil half-life in field studies is 30 to 70 days, with much of the loss probably due to volatilization (3, 4, 7).

Breakdown of Chemical in Surface Water

In water, oxyfluorfen is rapidly decomposed by light (4). Because oxyfluorfen is nearly insoluble in water and has a tendency to adsorb to soil, it is unlikely to remain in water. It will instead adsorb to suspended particles or sediments (7).

Breakdown of Chemical in Vegetation

There is very little movement of oxyfluorfen within treated plants. It is not readily metabolized by plants, but since it is not readily taken up by roots, residues in plants are very low (4). In crop rotation studies, residues of oxyfluorfen were found in small grains, but not in root or vegetable crops grown on previously treated fields (6). When carrots, lettuce, oats and cotton were planted in plots treated with 0.25 to 0.5 pounds per acre of radio-labeled oxyfluorfen on year prior to planting, low levels of residues were found in carrots and oats, but not in cotton or lettuce (7).

PHYSICAL PROPERTIES AND GUIDELINES

Oxyfluorfen is a white to orange or red-brown crystalline solid with a smoke-like odor (1, 2, 4). It may decompose if exposed to UV light (2).

Oxyfluorfen is stable under normal temperatures and pressures, but poses a slight fire hazard if exposed to heat or flame, and a fire and explosion hazard in the presence of strong oxidizers. It may burn but will not readily ignite. It may form flammable or explosive dust-air mixtures. Avoid contact with strong oxidizers, excessive heat, sparks or open flame. Thermal decomposition may release highly toxic fumes of fluorides and chlorides and toxic oxides of nitrogen and carbon. Workers handling oxyfluorfen should wear goggles to prevent eye contact with this chemical and protective clothing to prevent prolonged skin contact (2).

Exposure Guidelines:

No occupational exposure limits have been established for oxyfluorfen by OSHA, NIOSH or ACGIH (2).

Rohm and Haas recommended TWA: 0.2 mg/m3 (2)
Rohm and Haas recommended STEL: 1.6 mg/m3 (2)

Physical Properties:

CAS #: 42874-03-3
Chemical name: 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluromethyl)benzene
Chemical Class/Use: diphenyl ether herbicide
Specific gravity: 1.35 at 73 degrees C (2)
H20 solubility: nearly insoluble (1); 0.1 ppm (2).
Solubility in other solvents: readily soluble in most organic solvents (1)
Melting point: 181-183 degrees F (83-84 degrees C) (2)
Boiling point: > 464 degrees F (> 240 degrees C), decomposes (2), 358.7 (7).
Decomposition temperature: > 240 degrees C (4)
Flashpoint: > 200 degrees F (> 93 degres C) (2)
Vapor pressure: negligible at 25 degrees C (2); 2 x 10 to the minus 6 power mm Hg at 25 degrees C (4).
Koc: 100,000 (3, 6)

BASIC MANUFACTURER

Rohm and Haas Co.
Agricultural Chemicals
Independence Mall West
Philadelphia, PA 19105

Review by Basic Manufacturer:

Comments solicited: April, 1993
Comments received: May, 1993

REFERENCES

  1. Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister Publishing Company, Willoughby, OH.
  2. Occupational Health Services, Inc. 1992 (Nov. 17). MSDS for Oxyfluorfen. OHS Inc., Secaucus, NJ.
  3. U. S. Department of Agriculture, Soil Conservation Service. 1990 (Nov.). SCS/ARS/CES Pesticide Properties Database: Version 2.0 (Summary). USDA - Soil Conservation Service, Syracuse, NY.
  4. WSSA Herbicide Handbook Committee. 1989. Herbicide Handbook of the Weed Science Society of America, 6th Ed. WSSA, Champaign, IL.
  5. U.S. Environmental Protection Agency. May 27, 1992. Pesticide tolerances for oxyfluorfen. Federal Register 57 (102): 22202-3.
  6. US Environmental Protection Agency. March 13, 1992. Pesticide Environmental Fate One Line Summary: Oxyfluorfen. Environmental Fate and Effects Division, US EPA, Washington, DC.
  7. US Environmental Protection Agency. July 20, 1984. EEB Chemical Profile: Oxyfluorfen. US EPA, Washington, DC.