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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

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

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Quizalofop-p-ethyl

Trade and Other Names: Trade and other names of products containing quizalofop-p-ethyl include Assure II, Copilot, Pilot Super, Sheriff, Targa D+, and Targa Super Quizalofop. The compound may be found in formulations with other herbicides such as benazolin and clopyralid (trade name Benazalox).

Regulatory Status: The compound is a General Use Pesticide (GUP). Quizalofop-p-ethyl is a slightly toxic compound in EPA toxicity class III. End-use products are required to have the Signal Word CAUTION on their labels.

Chemical Class: phenoxy compound

Introduction: Quizalofop-p-ethyl is a selective, postemergence phenoxy herbicide. It is used to control annual and perennial grass weeds in potatoes, soybeans, sugar beets, peanuts, vegetables, cotton and flax, as well as other crops.

Quizalofop-p and quizalofop-p-ethyl should not be confused with quizalofop or quizalofop ethyl. The latter two compounds are distinctly different from the former two. The material in this profile refers only to the technical compound quizalofop-p-ethyl unless otherwise stated.

Formulation: Not Available

Toxicological Effects:

• Acute toxicity: Quizalofop-p-ethyl is slightly toxic by oral exposure. The reported oral LD50 values of the compound are 1210 to 1670 mg/kg in male rats, and 1182 to 1480 mg/kg in female rats [5,6]. Mice are only slightly less susceptible to the compound. Quizalofop-p-ethyl has reported LD50 values of 1753 to 2350 mg/kg in male mice and 1805 to 2360 mg/kg in female mice [5.6]. For the formulated product Assure, the reported oral LD50 values are 6600 mg/kg in male rats and 5700 in female rats [5]. Exposure of the skin of rabbits to the compound indicated that the compound is only slightly toxic by this route as well. The acute percutaneous (absorbed through the skin) LD50 for quizalofop-p-ethyl in mice, rats, and rabbits is greater than 2000 mg/kg [6]. For the formulated product Assure, the reported dermal LD50 in rabbits is greater than 5000 mg/kg [5]. Quizalofop-p-ethyl is slightly to practically nontoxic via inhalation, both in technical form and formulation. Reported 4-hour inhalation LC50s values are 5.8 mg/L for technical quizalofop-p-ethyl and 75 mg/L for Assure in rats [5]. Quizalofop-p-ethyl is nonirritating to the skin and only slightly irritating to the eyes in rabbits [5]. It is nonsensitizing to the skin of guinea pigs. The Assure formulation, however, is severely irritating to rabbit eyes [5].
• Chronic toxicity: In a 1-year feeding study on dogs, doses of up to 10 mg/kg/day (the highest dose tested in that study) caused no observed effects [31]. In a 90-day feeding study in rats, doses of 6.4 mg/kg/day and higher produced liver lesions and increased liver weight [31]. In a 2-year study of rats, doses of 5 mg/kg/day produced no observed effects [31].
• Reproductive effects: Data from reproductive studies indicated only decreased body weight gains, and did not report findings of impaired reproductive function in test animals [31]. A 6-month study in dogs found atrophy of the semeniferous tubles at doses of 2.5 mg/kg/day, but was unclear whether this was extensive enough to result in impaired reproductive function [31]. These data are insufficient to draw conclusions regarding the likely reproductive effects of quizalofop-p-ethyl in animals, but suggest that effects on human reproduction are unlikely under normal circumstances.
• Teratogenic effects: In a two-generational study in rats, doses of 2.5 mg/kg/day and higher produced increased liver weights in offspring [31]. No teratogenic effects were observed in another study in rats at doses of up to 300 mg/kg/day (the highest doses tested) over an unspecified period, although maternal decreases in body weight, food consumption, and corpora lutea were observed at doses of 100 mg/kg/day [31]. These data suggest that teratogenic or developmental effects are unlikely in humans.
• Mutagenic effects: The results of many assays for mutagenicity and genotoxicity of quizalofop-p-ethyl show no mutagenic or genotoxic activity. Quizalofop-p-ethyl was not found to be mutagenic in the Ames assay, either with or without metabolic activation, nor was mutagenic activity seen in Chinese hamster ovary cell culture tests [6]. Assays for chromosome structural aberrations and alterations in DNA damage repair capacity were also negative [5].
• Carcinogenic effects: In an 18-month carcinogenicity study on mice, increased liver weights, changes in blood chemistry, and some changes in liver tissue structure were detected, but no carcinogenic or tumor-causing activity was reported [8]. This study suggests that this compound is not carcinogenic.
• Organ toxicity: Available data show that the target organ in test animals has consistently been the liver in rats and dogs [8]. It is possible that testes may be a target organ in some species; e.g., dogs [7].

• Fate in humans and animals: Quizalofop-p appears to be rapidly broken down in mammals. More than 90% of a single oral dose is eliminated in urine within 3 days [6].

Ecological Effects:

• Effects on birds: Quizalofop-p-ethyl is practically nontoxic to birds. The reported 8-day feeding (dietary) LC50 is greater than 5000 ppm in bobwhite quail and mallard ducks. The reported LD50 for quizalofop-p-ethyl is greater than 2000 mg/kg in mallard ducks [5].
• Effects on aquatic organisms: Quizalofop-p-ethyl is highly to very highly toxic to fish. Reported 96-hour LC50 values are 10.7 mg/L in rainbow trout and 0.46 to 2.8 mg/L in bluegill sunfish [5].
• Effects on other organisms: Quizalofop-p-ethyl is practically nontoxic to bees, with a 48-hour contact LD50 of greater than 100 mg/bee [7].

Environmental Fate:

• Breakdown in soil and groundwater: Quizalofop-p-ethyl is moderately persistent in soils, with a reported half-life of 60 days [5,6]. It may be more rapidly broken down in soil with high microbial activity [5]. It is moderately to strongly sorbed to soils [5], and studies indicate very low soil mobility [5]. It should not leach significantly into water.
• Breakdown in water: No data are currently available.
• Breakdown in vegetation: No data are available regarding the breakdown of the compound; however, it is absorbed from the leaf surface and translocated throughout the plant. It accumulates in the active growing regions of stems and roots [5].

Physical Properties:

• Appearance: The compound is a pale brown crystal [6].
• Chemical Name: (R)-2-[4-(6-chloroquinoxalin-2-yloxy)phenoxy]propionic acid [6]
• CAS Number: 100646-51-3
• Molecular Weight: 372.80
• Water Solubility: 0.4 mg/L @ 20 C [6]
• Solubility in Other Solvents: s. in hexane; v.s. in acetone, ethanol, and xylene [6]
• Melting Point: 76-77 C [6]
• Vapor Pressure: 0.000011 mPa @ 20 C [6]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 510 [5]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Zeneca Agricultural Products
1800 Concord Pike
Wilmington, DE 19897

• Phone: 800-759-4500
• Emergency: 800-759-2500
  

References:

References for the information in this PIP can be found in Reference List Number 7

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.