Fluroxypyr

Do not use or store near heat or open flame.

Stable under normal conditions. Decomposes above melting point.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

Do not contaminate water when disposing of equipment washwaters.

Do not apply directly to water, or to areas where surface water is present or to intertidal areas below the mean high water mark.

Do not allow livestock to graze treated areas or harvest treated forage within 7 days of application.

Do not apply this product directly to, or otherwise permit it to come in direct contact with, susceptible crops or desirable plants... . Avoid applications where proximity of susceptible crops or other desirable plants is likely to result in exposure to spray or spray drift. Do not contaminate irrigation ditches or water used for domestic purposes.

For several good reasons, .... herbicides ... should be handled and applied only with full attention to safety measures that minimize personal contact. Many formulations contain adjuvants (stabilizers, penetrants, surfactants) that may have significant irritating and toxic effects. A number of premixed formulations contain two or more active ingredients; the companion pesticides may be more toxic than the principal herbicide. Good hygienic practice should not be disregarded just because a pesticide is reported to have a high LD50 in laboratory rodents.

Tolerances are established for combined residues of fluroxypyr 1-methylheptyl ester [1-methylheptyl ((4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy)acetate] and its metabolite fluroxypyr [((4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy)acetic acid] in or on the following raw agricultural commodities. [Table#6126]

LD50 Northern Bobwhite Quail (Colinus virginianus) oral gavage > 2000 mg a.i./kg

LD50 Northern Bobwhite Quail (Colinus virginianus) oral > 5000 mg a.i./kg

LD50 Mallard duck (Anas platyrhynchos) oral gavage > 2000 mg a.i./kg /Fluroxypyr-1-methylheptyl ester/

LD50 Honeybee (Apis mellifera) contact > 25ug a.i./bee for 48 hr /Fluroxypyr acid (technical grade) (98.3% a.i.)/

For more Ecotoxicity Values (Complete) data for Fluroxypyr (38 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), Koc ranges of 53-91 (avg of 74)(2) and 50-136(3), measured in a variety of different soils, indicate that fluroxypyr is expected to have high mobility in soil(SRC). Lysimeter and field studies have demonstrated that leaching may not be an important fate process for fluroxypyr in the soil environment(4-6); although fluroxypyr may be highly mobile in soil(5,6), degradation via microbial metabolism may attenuate the importance of leaching(SRC). Volatilization of fluroxypyr from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.72X10-11 atm-cu m/mole(SRC) based upon its vapor pressure, 3.75X10-7 mm Hg(4), and water solubility, 7300 mg/L(4). Biodegradation is the important fate process in soil(7,8) with observed half-lives ranging from 1 to 3 weeks(7). Microbial degradation metabolites include 4-amino-3,5-dichloro-6-fluoropyrid-2-ol,4-amino-3,5-dichloro-2-methoxypyridine, and carbon dioxide(8). Soil dissipation half-lives in laboratory studies have been observed to range from 5-9 days (at 23 °C)(4) and 6.6-21.3 days(9) in a variety of soil types.

TERRESTRIAL FATE: The methylheptyl derivative form of fluroxypyr (also known as meptyl fluroxypyr) is a registered herbicide and the common commercial form of fluroxypyr(1). When applied as a herbicide, meptyl fluroxypyr metabolizes rapidly via hydrolysis to form fluroxypyr(2,4); in soil slurries, the half-life hydrolysis rate of meptyl fluroxypyr to fluroxypyr is reported as 2-5 hours at pH6-7, 22-24 °C(4).

AQUATIC FATE: Based on a classification scheme(1), measured Koc ranges of 50-136(2-3), indicate that fluroxypyr is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(4) based upon an estimated Henry's Law constant of 1.72X10-11 atm-cu m/mole(SRC), derived from its vapor pressure, 3.75X10-7 mm Hg(5), and water solubility, 7300 mg/L(5). Abiotic hydrolysis and direct photolysis are not important fate processes in water(6); the fluroxypyr half-life in deionized aqueous solutions exposed to sunlight is about one year(6). According to a classification scheme(7), an estimated BCF of 3.2(SRC), derived from its log Kow of 2.20(8) and a regression-derived equation(9), suggests the potential for bioconcentration in aquatic organisms is low. Biodegradation is the important fate process in water(6). In aqueous laboratory studies at 25 °C using river sediment inocula, fluroxypyr had biological half-lives of 0.5-2 weeks(6); rates were similar under both aerobic and anaerobic conditions(6).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), fluroxypyr, which has a vapor pressure of 3.75X10-7 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase fluroxypyr is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 13 hours(SRC), calculated from its rate constant of 2.88X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase fluroxypyr may be removed from the air by wet or dry deposition(SRC). The results of one study that measured direct photolysis of fluroxypyr in aqueous solution by sunlight (half-life of one year) suggest direct photolysis in the atmosphere with not be an important fate process(SRC).

/BIRDS and MAMMALS/ Northern Bobwhite Quail (Colinus virginianus), > 16 weeks old, 5/sex/group, were given Fluroxypyr acid (98.8% a.i.) in a corn oil vehicle by gastric gavage. There was one mortality at 2000 mg/kg within 24 hours of dosing and one mortality in control group 7 days after dosing. No signs of toxicity during 14 day observation period; no treatment-related effects on body weight or food consumption. /From table/

/BIRDS and MAMMALS/ Mallard Duck (Anas platyrhynchos), >16-wks-old, 5/sex/group, were given Fluroxypyr acid (Dowco 433 acid) in corn oil vehicle: 0, 500, 1000, or 2000 mg/kg bw gavage. No mortality attributed to treatment; no dose-related effects on bodyweights, which were considered to be within normal limits; and no dose-related effects on food consumption, which was variable. Upon post-mortem examination, some birds had enlarged and discolored livers. Full study indicates that a number of birds in Groups 2, (4/10), 3 (3/10), and 4 (2/4) were found to have enlarged livers which were orange-yellow in color and hard to the touch. In two birds in Group 3 the body cavity was found to be filled with clear fluid. /From table/

/BIRDS and MAMMALS/ Northern Bobwhite Quail (Colinus virginianus), 12-days-old at test initiation, 10/dose group. 30 in control group, were fed Fluroxypyr acid (Dowco 433 acid): Dietary concentrations: Nominal: 0, 658, 988, 1481, 2222, 3333 or 5000 mg/kg of diet for 5 days followed by basal diet only for 5 days followed by a 5 day post-treatment period. Average body weights: about 24 g/bird. Average food consumption: about 8 g/bird. Food consumption factor: about 0.3. Mortality: 1/10 at concentrations of 658 ppm, 2222 ppm, and 3333 ppm. No mortality in controls or in the 988 ppm, 1481 ppm, and 5000 ppm dose groups. Mortality was not dose-related and none of the control to dose group mortalities are statistically significant. No treatment-related effects were observed on food consumption or body weight ... No changes in gross tissue examination. /From table/

/BIRDS and MAMMALS/ Northern Bobwhite Quail (Colinus virginianus), 11-days-old at test initiation, 10 birds/dose group, were fed Fluroxypyr MHE ( Dowco 433 ester): Dietary levels of 658, 988, 1481, 2222, 3333, or 5000 ppm for 5 days with a 5 day post-treatment period. Average body weights: about 20 g/bird. Average food consumption: about 3 g/bird. Food consumption factor: about 0.15. One mortality occurred at doses of 988, 1481, and 2222 ppm, and two mortalities occurred at 3333 ppm; no mortality at 5000 ppm. No dose-related effects on general bird health, bodyweight, or food consumption; and no abnormalities were found at post-mortem examination. /Fluroxypyr-1-methylheptyl ester/ /From table/

For more Ecotoxicity Excerpts (Complete) data for Fluroxypyr (30 total), please visit the HSDB record page.

In a study to determine C-14 uptake in rotational crops 1, 4 and 12 months after application of the formulation, fluroxypyr dissipated too rapidly to be taken up by most of the rotational crops. Wheat plants absorbed only small quantities through the roots, and these residues were not deposited in the grain, but in the straw/chaff fraction, which is recycled back to the field(1).

A batch adsorption study using four different soil types (organic carbon content range of 0.22-3.08%) experimentally determined a Koc range of 53-91 for fluroxypyr with an average Koc of 74(1). A Koc range of 50-136 was measured in nine arable soils from southern England(2). According to the classification scheme(3), these measured Koc values suggest that fluroxypyr is expected to have a high mobility in soil.

Lysimeter and field studies have demonstrated that leaching may not be an important fate process for fluroxypyr in the soil environment(1-3); although fluroxypyr may be mobile in soil(2,3), degradation via microbial metabolism may attenuate the importance of leaching(SRC).

AEROBIC: In soil, fluroxypyr is rapidly degraded by microorganisms to 4-amino-3,5-dichloro-6-fluoropyrid-2-ol,4-amino-3,5-dichloro-2-methoxypyridine, and carbon dioxide. Half-lives ranged from 1 to 3 weeks(1). In sediment/soil solutions, under aerobic conditions, 4-amino-3,5-dichloro-6-fluoropyrid-2-ol, 4-amino-3-chloro-6-fluoropyrid-2-ol, and carbon dioxide were formed(2). In a two-year study of the metabolism of C14-radiolabeled fluroxypyr on two types of soil in lysimeters, fluroxypyr was rapidly metabolized and by the end of 3 months, only 1% of the applied parent was detected(3). In a study of C14-radiolabeled fluroxypyr-methylheptyl ester on four types of soils, the ester rapidly hydrolyzed to fluroxypyr, and fluroxypyr was then found to degrade with half-lives from 7 to 23 days, depending on soil type(4).

ANAEROBIC: In sediment/soil solutions, under anaerobic conditions, 4-amino-3,5-dichloro-6-fluoropyrid-2-ol, 4-amino-3-chloro-6-fluoropyrid-2-ol, 4-amino-5-chloro-6-fluoropyrid-2-ol, and carbon dioxide were formed. Degradation half-lives of 0.5-2 weeks were observed(1).

An estimated BCF of 3.2 was calculated in fish for fluroxypyr(SRC), using a log Kow of 2.20(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low.

The Henry's Law constant for fluroxypyr is estimated as 1.72X10-11 atm-cu m/mole(SRC) derived from its vapor pressure, 3.75X10-7 mm Hg(1), and water solubility, 7300 mg/L(1). This Henry's Law constant indicates that fluroxypyr is expected to be essentially nonvolatile from water surfaces(2). Fluroxypyr is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.75X10-7 mm Hg(1).

/LABORATORY ANIMALS: Acute Exposure/ Rats (Fischer 344, 6 to 7-wks-old, 175-184 g (males), 120-129 g (females), 5/sex/group, fasted) were given XRM-5316 (fluroxypyr 25.6%) [fluroxypyr-MHE], gavage dose levels: 500, 2000, or 5000 mg XRM/kg body weight /followed by a/ 14-day observation period. Mortality: 4/5 males and 5/5 females in high-dose group. All of the high dose females and one of the high dose males died on Day 1; remaining males died on Day 2. Signs of toxicity: decreased activity, lacrimation, salivation, incoordination, labored breathing, and closed eyelids. No adverse findings at necropsy. /Fluroxypyr-1-methylheptyl ester/

/LABORATORY ANIMALS: Acute Exposure/ Guinea Pig (Hartley Albino, 10 males, weight not specified) received XRM-5316 (25.6% fluroxypyr MHE) for a test of dermal sensitization. Induction Phase Dermal application of 0.4 mL (10% dilution) applied to shaved, intact skin of left side of each guinea pig and covered with a gauze patch. Challenge Phase 2 weeks after the induction phase, similar approach was taken: 0.4mL of 1% test material or 5% positive control were applied to the right side (clipped free of hair) of each guinea pig) for a 6-hour exposure period. Application sites were graded for sensitization 24 and 48 hours after the challenge application. Results: XRM-5316 was not a dermal sensitizer under the conditions of the study. Edema was not observed in any of the guinea pigs in either group during the induction and challenges phases of the experiment. All of the positive control guinea pigs displayed a positive response, as expected. NOTE: Concentration of the test material was decreased from 10% to 5% due to erythema observed at the application site of two guinea pigs after the first induction application and again reduced from 5% to 1% due to erythema observed in one guinea pig after the second induction application. The concentration of the positive control was decreased from 10% to 7.5% due to erythema observed in one guinea pig after the second induction application. /Fluroxypyr-1-methylheptyl ester/

/LABORATORY ANIMALS: Acute Exposure/ Rabbits (New Zealand White, 5 male and 1 female , 2.5-2.9 kg bw) received XRM-5316 (25.6% fluroxypyr MHE) for dermal irritation test. Dosing: 0.5 mL aliquot for 4 hours to 6.25 sq cm on backs/flanks. Post treatment observations for dermal irritation took place at 15 and 30 minutes, 4, 24, 48, and 72 hours. Irritation scored via Draize method. XRM found to be a slight dermal irritant; all observations of erythema and edema resolved within 48 hours. Primary irritation index: 0.75. /Fluroxypyr-1-methylheptyl ester/

/LABORATORY ANIMALS: Acute Exposure/ Rabbits (New Zealand, 2.3-3.1 kg, 5/sex/group) received XRM-5316 (25.6% fluroxypyr MHE) dermally. Dose: 2000 mg XRM/kg bw applied to shaved back; test material held in contact with skin by gauze dressing and non-irritating tape. 24-hour exposure period, after which the skin was washed with mild soap and water. 2 week observation period; body weights recorded on Days 1, 2, 8, and 15. Results: No mortality; clinical signs observed at application site included burn, edema, erythema, and scaling in all rabbits of each gender. /Fluroxypyr-1-methylheptyl ester/

Tolerances are established for combined residues of fluroxypyr 1-methylheptyl ester [1-methylheptyl ((4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy)acetate] and its metabolite fluroxypyr [((4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy)acetic acid] in or on the following raw agricultural commodities. [Table#6127]

Used as herbicide for cereals; [Merck Index] Registered for use on wheat, barley, oats, and farm land; [Reference #1]

Farming (Pesticides) [Category: Industry]

For fluroxypyr (USEPA/OPP Pesticide Code: 128959) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./

Herbicide ... effective by postemergence control of broadleaf weeds in cereal, fallow land, and on-farm non-cropland.

Directed applications are used against herbaceous and woody broad-leaved weeds in orchards (apple only) and plantation crops (rubber and oilpalm), and broad-leaved brush spp. in conifer forests. Post-emergence, broadcast applications of fluroxypyr in maize up to the 6-leaf stage of the crop are used for control of Calystegia sepium, Convolvulus arvensis and Solanum nigrum.

Herbicide used to control established broadleaf weeds and woody brush. It is registered by the U.S. Environmental Protection Agency (EPA) for the following applications: Pasture and rangeland, Crops - sweet corn, field corn, wheat, barley, oats, millet, sorghum, onions, apple & pear orchards, Pine plantations, Fallow cropland, Industrial sites, Rights-of-way - electrical power lines, communication lines, pipelines, roadsides, railroads, Residential lawns, Recreational sites - golf courses, parks, sports fields

Fluroxypyr is produced using a complex and proprietary process

Fluroxypyr can be synthesized by reacting 4-amino-3,5-dichloro-2-(methylsulfonyl)pyridine with methylglycolate, although it is not clear that this method of synthesis is currently used to produce fluroxypyr.

Formulation types: Emulsifiable Concentrate, Emulsion (oil in water), Suspo-Emulsion

Fluroxypyr Mixtures: 'Holster' (+ 2,4-D+ dicamba) (SumiAgro); 'Treble' (+ ioxynil+ bromoxynil) (Barclay) Discontinued products mixtures: 'Advance' * (+ ioxynil+ bromoxynil) (Dow, Zeneca); 'Crusader S' * (+ ioxynil+ bromoxynil+ clopyralid) (Dow); 'EF1166' * (+ metosulam) (Dow AgroSciences, Bayer); 'Hotspur' * (+ ioxynil+ clopyralid) (Dow); 'Sickle' * (+ bromoxynil) (Dow)

Formulated as Fluroxypyr-meptyl: 'Starane' (Dow AgroSciences); 'Hurler' (Barclay); 'Tomahawk' (Makhteshim-Agan)... Mixtures: 'Vista' (Dow AgroSciences); 'Reaper' (GreenCrop); 'Tomigan' (Makhteshim-Agan) mixtures: 'Doxstar' (+ triclopyr-butotyl) (Dow AgroSciences); 'Pastor' (+ triclopyr-butotyl+ clopyralid) (Dow AgroSciences); 'Plenum' (+ picloram-triisopropanolammonium) (Dow AgroSciences); 'Bastion T' (+ mecoprop-P) (Rigby Taylor); 'Trilin' (+ ioxynil+ bromoxynil) (Makhteshim-Agan)

Forumulated as Fluroxypyr-2-butoxy-1-methylethyl Mixtures: 'Staraminex' (+ MCPA-potassium) (Istrochem)

Starane and Vista are commercial formulations that contain fluroxypyr as the sole active ingredient. Vista is the only fluroxypyr formulation labeled for forestry applications, and is the only commercial formulation likely to be used in Forest Service programs ... There are two available formulations of Vista: Vista Specialty Herbicide and Vista XRT (Ultra), both of which are produced by Dow AgroSciences ... Vista Specialty Herbicide contains 26.2% (w/w) of the fluroxypyr 1-methylheptyl ester, which is equivalent to 1.5 lbs of fluroxypyr acid (a.i.) per gallon. The product label specifies that the formulation contains petroleum distillates. The material safety datasheet further specifies that the formulation contains < 5.4% naphthalene and 5.1% 1-methyl-2-pyrrolidinone. The concentration of fluroxypyr 1-methylheptyl ester in Vista XRT is substantially greater, i.e., 45.2%, compared with the 26.2% in Vista Specialty Herbicide. More importantly, Vista XRT contains much lower concentrations of named inerts, i.e., 0.5% naphthalene and 0.1% 1-methyl-2-pyrolidinone. /Flurorxypyr 1-methylheptyl ester/

Herbicides

Environmental transformation -> Pesticides (parent, predecessor)