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
Publication Date: 9/95
TRADE OR OTHER NAMES
The common name haloxyfop is also used for haloxyfop-methyl and
haloxyfop-ethoxyethyl. Trade names include Verdict, Gallant, Zellek, and Dowco
453 ME (haloxyfop methyl) or Dowco 453 EE (haloxyfop ethoxyethyl)(1).
Registration is pending for use of haloxyfop in the United States (3).
Haloxyfop is in the pyridine chemical family (2). It is produced in two
forms, haloxyfop-methyl and haloxyfop-ethoxyethyl. Both are used as pre- and
postemergence selective herbicides. They control annual and perennial grasses
in sugar beet, oilseed, potatoes, leaf vegetables, onions, sunflowers,
strawberries, and other crops. Haloxyfop-ethoxyethyl and haloxyfop-methyl are
absorbed into the plant and inhibit growth (1). The EPA classifies haloxyfop
as toxicity class II-moderately toxic. All products containing haloxyfop bear
the Signal Word "Warning." It is available as an emulsifiable concentrate (3).
The oral LD50, the dose of haloxyfop-methyl that kills half of the study
animals, is 393 mg/kg for rats. The LD50 is greater than 5,000 mg/kg for
rabbits whose skin is exposed to haloxyfop-methyl (4). Haloxyfop-ethoxyethyl
has an oral LD50 of 518-531 mg/kg for rats. The dermal LD50 is greater than
2000 mg/kg for rats and greater than 5,000 mg/kg for rabbits.
Both haloxyfop forms are non-irritating to skin and do not cause skin
sensitization. They are mild eye irritants (1). The symptoms of toxicity in
rats are reduced food intake and reduced food consumption. They may also cause
liver and kidney damage (4).
In rats, oral doses of 10 and 50 mg/kg/day of haloxyfop-ethoxyethyl from
days 6 to 16 of pregnancy reduced the number of live offspring per litter and
caused vaginal bleeding in the mother (5).
Oral doses of 50 mg/kg/day of haloxyfop-ethoxyethyl in rats between days
6 and 16 of pregnancy caused developmental abnormalities in the offspring's
urogenital system and death to the fetus (5). Oral doses of 7.5 mg/kg/day of
haloxyfop-methyl given to rats from days 6 to 15 of pregnancy caused delayed
bone formation in the offspring (6).
No information is currently available.
Studies show that 0.1 mg/kg/day of haloxyfop-methyl for two years, the
highest dose tested, does not cause cancer in rats. Similarly, 0.6 mg/kg/day
for two years, the highest dose tested, is not carcinogenic to mice (6).
Doses of 100 mg/kg/day of haloxyfop-methyl caused kidney damage in adult
rats (4). Doses of 0.6 mg/kg/day for 2 years in mice caused reduced body
weight gains and increased liver weights in mice. In dogs, 5 mg/kg/day causes
a significant decrease in serum cholesterol, as well as a decrease in thyroid
Fate in Humans and Animals
In rats, haloxyfop-ethoxyethyl undergoes metabolism to haloxyfop which is
excreted in feces and urine (1).
Effects on Birds
Haloxyfop-methyl and haloxyfop-ethoxyethyl are practically non-toxic to
birds. The oral LD50 is greater than 2,150 mg/kg for mallard ducks. The
dietary LC50 (8 day) is greater than 5,620 mg/kg for bobwhite quail (1, 2).
Effects on Aquatic Organisms
Haloxyfop-methyl is practically non-toxic to fish. The LC50, the
concentration in water at which half of the test animals died, ranges from 96
to greater than 1000 mg/kg (2). Haloxyfop-ethoxyethyl is moderately to highly
toxic to fish. The LC50 (96 hour) is 0.54 mg/l for fathead minnows, 0.28 mg/l
for bluegill sunfish, and 1.8 mg/l for rainbow trout. The LC50 (48 hours) for
Daphnia is 4.64 mg/l (1).
Effects on Other Animals (Nontarget species)
Haloxyfop is not toxic to bees. The contact and oral LD50 (48 hours) is
100 micrograms haloxyfop/bee (1).
Breakdown of Chemical in Soil and Groundwater
Haloxyfop-ethoxyethyl is converted to haloxyfop in soil. The half-life of
haloxyfop-ethoxyethyl, the amount of time needed to reduce its concentration
by half, is greater than one day on silty clay loam at 20 degrees C. The half-
life of haloxyfop in soil is 55-100 days depending on the soil (1). Leaching
is moderate (5).
Breakdown of Chemical in Surface Water
The half-life of haloxyfop in water is 33 days for haloxyfop at pH 5, 5
days at pH 7, and a few hours at pH 9 (1).
Breakdown of Chemical in Vegetation
No information is currently available.
PHYSICAL PROPERTIES AND GUIDELINES
Haloxyfop (acid) is a white crystal with an offensive odor. Haloxyfop-
ethoxyethyl is a colorless crystal which is hydrolyzed to haloxyfop under
acidic and alkaline conditions. The rate of hydrolysis increases with
temperature (1). Haloxyfop-methyl is an amber to straw yellow solid with a
mild aromatic odor. It is stable to UV light and in high temperatures. There
is no decomposition after 88 hours at 200 degrees C.
|CAS#: ||Haloxyfop-ethoxyethyl 87237-48-7
|Chemical Name: ||2-(4-((3-chloro-5-trifluoro methyl)-2-pyridinyl) oxy)phenoxy)-2-ethoxyethyl ester
|Chemical name: ||2-(4-(3-chloro-5-(trifluoro methyl)-2-pyridinyl)oxy)phenoxy-methyl ester
|Molecular Weight: ||361.7 (acid)
|Melting points: ||107-108 degrees C (acid)
56-58 degrees C (haloxyfop-ethoxyethyl) (1)
55-57 degrees C (haloxyfop-methyl)
|Solubilities in water: ||0.5 mg/l (haloxyfop-ethoxyethyl)
9.3 mg/l (haloxyfop-methyl)(7)
|Solubilities in solvents:
| ||xylene: ||125g/100 ml (haloxyfop-ethoxyethyl)
127g/100 ml (haloxyfop-methyl)
| ||acetone: ||>100g/100 ml (acid, haloxyfop ethoxyethyl, haloxyfop-methyl)
| ||toluene: ||>100g/100 ml (ethoxyethyl)
11.8g/100 ml (acid)
|Vapor pressure: ||<1.3 x 10 to the minus 7 mm Hg at 25 degrees C (acid)
3.4 x 10 to the minus 6mm Hg at 25 degrees C (haloxyfop ethoxyethyl)
6.5 x 10 to the minus 7 mm Hg at 25 degrees C (haloxyfop-methyl)
|Partition coefficient (octanol/water): ||(haloxyfop-ethoxyethyl) 29,500 (1)
All guidelines given are for haloxyfop-methyl.
|RfD: ||5.0 x 10 -5 mgkgday (kidney effects)(4)
|NOEL: ||0.005 mg/kg/day (4)
|LEL: ||0.05 mg/kg/day (reduced fertility) (4)
9002 Purdue Road
Indianapolis, IN 46268-1189
Review by Basic Manufacturer:
Comments solicited: October, 1994
Comments received: November, 1994
The Agrochemicals Handbook, Third Edition. 1994. Royal Society of
Chemistry Information Systems, Unwin Brothers Ltd., Surrey, England.
Meister, R.T. 1994. Farm Chemicals Handbook '94. Meister Publishing
Company. Willoughby, OH.
Meister, R.T. 1992. Farm Chemicals Handbook '92. Meister Publishing
Company. Willoughby, OH.
National Institute for Occupational Safety and Health (NIOSH). 1993.
Registry of Toxic Effects of Chemical Substances (RTECS). NIOSH. Cincinnati,
Machera, K. 1993. Developmental Toxicity of Haloxyfop Ethoxyethyl
Ester in the Rat in Bulletin of Environmental Contamination and Toxicology,
Vol.51, No.4. pp. 625-632.
U.S. Environmental Protection Agency. 1994. Integrated Risk
Information System (IRIS) through TOXNET. U.S. EPA. Washington, DC.