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The information in this profile may be out-of-date.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

Esfenvalerate

Trade and Other Names: Trade names for the older fenvalerate compounds include Ectrin, Pydrin, Sanmarton, Sumifly, Sumiflower, and Sumitick. Trade names for the new product, esfenvalerate, include Asana XL, Halmark, and Sumi-alfa. The compound may also be listed as S-fenvalerate.

Regulatory Status: Most products containing esfenvalerate are General Use Pesticides (GUPs). The emulsified concentrate formulation is a Restricted Use Pesticide (RUP) because of possible adverse effects in aquatic organisms. Esfenvalerate is a moderately toxic pesticide in EPA toxicity class II; products containing it must contain the Signal Word WARNING on the label.

Chemical Class: pyrethroid

Introduction: Esfenvalerate is a synthetic pyrethroid insecticide which is used on a wide range of pests such as moths, flies, beetles, and other insects. It is used on vegetable crops, tree fruit, and nut crops. It may be mixed with a wide variety of other types of pesticides such as carbamate compounds or organophosphates. Esfenvalerate has replaced the naturally occurring compound fenvalerate (to which it is almost identical) for use in the U.S. Much of the data for fenvalerate is applicable to the pesticide esfenvalerate because the two compounds contain the same components. The only differences in the two products are the relative proportions of the four separate constituents (isomers). Esfenvalerate has become the preferred compound because it requires lower applications rates than fenvalerate, is less chronically toxic, and is a more powerful insecticide. The compound contains a much higher percentage of the one insecticidally active isomer (84% for esfenvalerate and 22% for fenvalerate).

Formulation: It may be mixed with a wide variety of other types of pesticides such as carbamate compounds or organophosphates. Esfenvalerate has replaced the naturally occurring fenvalerate( to which it is almost identical) for use in the U.S. Much of the data for fenvalerate is applicable to the pesticide esfenvalerate because the two compounds contain the same components. The only differences in the two products are the relative proportions of the four separate constituents (isomers). Esfenvalerate has become the preferred compound because it requires lower applications rates than fenvalerate, is less chronically toxic, and is a more powerful insecticide. The compound contains a much higher percentage of the one insecticidally active isomer (84% for esfenvalerate and 22% for fenvalerate).

Toxicological Effects:

• Acute toxicity: Esfenvalerate is a moderately toxic compound via the oral route. The reported oral LD50 of esfenvalerate is 458 mg/kg in rats. It is slightly toxic via the dermal route, with a reported dermal LD50 of 2500 mg/kg in rabbits. It is practically non-toxic via inhalation, with a reported inhalation LC50 of greater than 2.93 mg/L in rats [2,12]. Because esfenvalerate is a relatively new compound it has little usage history. The bulk of evidence related to acute poisonings in humans due to esfenvalerate comes from incidents in India. Nearly 600 individual cases of poisoning were reported between 1982 and 1988. These cases were due to improper handling of the pesticide. Acute toxic effects were observed in workers and among the general public. Symptoms of acute poisoning included dizziness, burning and itching (which was worsened by sweating and washing). Severe cases of direct contact caused blurred vision, tightness in the chest, and convulsions (2). The changes appear to be reversible. In rats, high acute exposure to esfenvalerate produced muscle incoordination, tremors, convulsions, nerve damage, and weight loss. The compound may produce nausea, vomiting, headache, temporary nervous system effects such as weakness, tremors, and incoordination at acute exposure levels in humans. Esfenvalerate is a strong eye irritant, producing tearing or blurring of vision.
• Chronic toxicity: Rats fed fenvalerate at concentrations of approximately 12.5 mg/kg/day for two years had no compound-related changes in the blood or urine [12]. In other studies significant reduction in body weight was the main adverse effect seen in both rats and mice of both sexes.
• Reproductive effects: In a three-generation rat study, low doses (up to 12.5 mg/kg/day) of fenvalerate produced no toxicity in the fetus. Some maternal toxicity was noted in the second generation at the higher dose. When pregnant mice and rabbits were fed low dietary levels of fenvalerate (2.5 mg/kg/day) on days 6 to 15 of gestation, there was maternal toxicity in both species. It seems that during pregnancy, the females are more sensitive to fenvalerate than they would otherwise be, even though the toxicity is not reflected in any effect on the fetus [5]. There are no specific data available for esfenvalerate, but it is not expected to cause reproductive effects at low doses.
• Teratogenic effects: Esfenvalerate did not produce any birth defects in offspring at low dietary doses [2]. It appears the the pesticide would not pose a teratogenic threat to humans at expected exposure levels.
• Mutagenic effects: Esfenvalerate shows no mutagenic effects. Numerous tests in hamsters, mice and rats show no signs of mutagenic activity associated with this compound [2]. It is likely that it poses no mutagenic risk to humans.
• Carcinogenic effects: A rat study of fenvalerate conducted over a wide range of doses of up to 75 mg/kg, for two years, resulted in no evidence of cancer. Mice fed diets containing small amounts of fenvalerate for two years showed no adverse effects [2]. It appears that fenvalerate does not cause cancer.
• Organ toxicity: Studies to date have not shown any dose-related effects on internal organs of test animals or in human populations [2].

• Fate in humans and animals: Cows treated with 0.1 or 0.5 g fenvalerate on their skin had 0.03 to 0.06% of the applied chemical in the milk. When the cows received fenvalerate orally at very low levels, about 0.50% of the dose appeared in the milk. Fenvalerate does not appear to be metabolized by bovine rumen, but it is degraded further down the digestive tract [32]. This happens rapidly with less than 0.02% of the parent compound found in the urine and 20% of the major metabolite present. Higher concentrations of the parent compound are present in the feces. In the rat, fenvalerate is rapidly broken down and almost completely eliminated within several days. One study indicated mammals eliminated 96% in the feces in 6 to 14 days [32]. While the data presented here are for fenvalerate, esfenvalerate behaves in the same manner [33].

Ecological Effects:

• Effects on birds: Esfenvalerate is slightly toxic to birds. Oral LD50 values for the compound are 1312 mg/kg in bobwhite quail and greater than 2250 mg/kg in mallard ducks [12].
• Effects on aquatic organisms: Based on laboratory studies, fish are very sensitive to esfenvalerate. It has a 96-hour LC50 of 0.0003 mg/L in bluegill, 0.0003 mg/L in rainbow trout, 0.001 mg/L in carp, and 0.0002 mg/L in killfish [5]. The LC50 in Daphnia magna, an aquatic invertebrate, is 0.001 mg/L. The pesticide is very highly toxic to these species. Water turbidity, such as would be found in the field, tends to reduce the toxicity of this compound [5]. Bioaccumulation factors in rainbow trout are about 400 times the background (ambient water concentration of the pesticide) levels [5].
• Effects on other organisms: Esenvalerate is highly toxic to bees. The compound tends to repel bees for a day or two after application, causing bee visitations to drop during that time [5]. Since most intoxicated bees die in the field before they can return to contaminate the hive, the brood is not exposed except by direct spray. Dried spray residues are not expected to pose a significant threat to bees [5].

Environmental Fate:

• Breakdown in soil and groundwater: Under field conditions, esfenvalerate is moderately persistent with a half-life ranging from about 15 days to three months depending on soil type [25]. In a soil laboratory study, 17% of the applied chemical was lost in 90 days. Esfenvalerate and its breakdown products are relatively immobile in soil and thus pose little risk to groundwater [11]. The compounds ability to bind to soil increases with increasing organic matter. It is very insoluble in water. Fenvalerate has not been found in over 100 tested groundwater supplies [34].
• Breakdown in water: Esfenvalerate will break down in water to one-half of the original amount (half-life) in about twenty-one days due to sunlight [11].
• Breakdown in vegetation: The parent compound is the residue most often found on foliage. In a series of trials in Canada where 16 varieties of fruits and vegetables were grown under typical outdoor conditions, no degradation products or metabolites were found (tests were sensitive to 0.05 mg/kg). Sampling was from 1 to 112 days after application. The half-life of esfenvalerate on plant surfaces is 2 to 4 weeks [31].

Physical Properties:

• Appearance: The pure compound exists as colorless crystals; the technical product as an amber liquid [12].
• Chemical Name: (S)-alpha-cyano-3-phenoxybenzyl(S)-2-(-4-chlorophenyl)-3-methylbutyrate [12]
• CAS Number: 66230-04-4
• Molecular Weight: 419.90
• Water Solubility: <0.3 mg/L at 25 C, insoluble in water [12]
• Solubility in Other Solvents: v.s. in hexane, acetone, chloroform, and methanol @ 20 C [12]
• Melting Point: 59-60 C [12]
• Vapor Pressure: 0.067 mPa @ 25 C [12]
• Partition Coefficient: 6.2201 [12]
• Adsorption Coefficient: 5300 [25]

Exposure Guidelines:

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

Basic Manufacturer:

DuPont Agricultural Products
Walker's Mill, Barley Mill Plaza
P.O. Box 80038
Wlimington, DE 19880-0038

• Phone: 800-441-7515
• Emergency: 800-441-3637
  

References:

References for the information in this PIP can be found in Reference List Number 2

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.