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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.


Publication Date: 9/93


Allethrin: Alleviate, Pynamin. d-trans allethrin: D-Trans Conc. 90%, bioallethrin, MGK 264 and Esbiothrin.


Pesticides containing allethrin must bear the signal word "Caution" on the product label. Containers of technical d-trans allethrin must bear the signal "Warning" (1).


Allethrin is used almost exclusively in homes and gardens for control of flies and mosquitoes, and in combination with other pesticides to control flying or crawling insects. The purified d-trans-isomer of allethrin is more toxic to insects and is used for control of crawling insects in homes and restaurants (1).

Allethrin is a synthetic duplicate of a component of pyrethrum. Pyrethrum is a botanical insecticide extracted from chrysanthemum flowers. Allethrin, the first synthetic pyrethroid, was introduced in 1949, and is a mixture of several isomeric forms. The most common form is a 4:1 mixture of the trans- and cis-isomers. It is available in aerosol, coil, mat, dust and oil formulations. Aerosol and spray formulations of the purified d-trans- isomer of allethrin are also available. D-trans allethrin is usually combined with synergists such as piperonyl-butoxide (1).

Unless stated otherwise, information in this PIP refers to unpurified allethrin.



Allethrin is slightly to moderately toxic by dermal absorption and ingestion (2). Short-term dermal exposure to allethrin may cause itching, burning, tingling, numbness, a feeling of warmth, with no dermatitis (2). Exposure to large doses by any route may lead to nausea, vomiting, diarrhea, hyperexcitability, incoordination, tremors, convulsive twitching, convulsions, bloody tears, incontinence, muscular paralysis, prostration and coma (2). Persons sensitive to ragweed pollen are at increased risk from exposure to allethrin (2).

Allethrin is a central nervous system stimulant (2). Heavy respiratory exposure caused incoordination and urinary incontinence in mice and rats (2).

The amount of a chemical that is lethal to one-half (50%) of experimental animals fed the material is referred to as its acute oral lethal dose fifty, or LD50. The toxicity of allethrin varies with the amounts of different isomers present. The oral LD50 for allethrin in male rats is 1,100 mg/kg, in female rats is 685 mg/kg (1), 370 mg/kg in mice, and 4,290 mg/kg in rabbits (2). The oral LD50 for d-trans allethrin in rats is 860 mg/kg (1). The dermal LD50 in rabbits is 11,332 mg/kg (2).


A dosage of 50 mg/kg/day for 2 years produced no detectable effect in the dog (2).

In a 90-day dietary study with rats fed 0, 25, 75, 250 or 500 mg/kg of bioallethrin, the NOEL was 25 mg/kg. Rats fed 75 mg/kg exhibited decreased body weight gain, increased liver weights and, in females only, increased levels of serum liver enzymes (5).

A 6-month study with dogs fed 0, 5, 25 or 125 mg/kg of bioallethrin, effects on the liver were seen at 5 mg/kg (5).

Reproductive Effects

No information was found.

Teratogenic Effects

No developmental defects were seen in the offspring of rats given doses as high as 195 mg/kg/day (5).

Mutagenic Effects

Allethrin has been found to be mutagenic under certain conditions in strains of the bacterium Salmonella typhinurium (3). However, 2 other tests of bioallethrin for mutagenicity (DNA damage and reverse mutation) were negative (5).

Carcinogenic Effects

Rats fed 2,000 mg/kg of d-allethrin for 2 years did not develop cancer (4, 5).

Organ Toxicity

Pyrethroids may cause adverse effects on the central nervous system. Long-term feeding studies have caused increased liver and kidney weights and adverse changes in liver tissues in test animals (2).

Fate in Humans and Animals

No information was found.


Allethrin degrades rapidly in the environment (5).

Effects on Birds

Allethrin is practically non-toxic to birds. The LD50 for technical allethrin in mallards is > 2,000 mg/kg; 5,620 ppm for d-cis/trans-allethrin in mallards and bobwhite quail; and 2,030 ppm for bioallethrin in bobwhite quail (5).

Effects on Aquatic Organisms

Allethrin is highly toxic to fish and aquatic invertebrates. The toxicity of allethrin in 27 species of warm and cold-water fish was measured. The results ranged from an LC50 of 2.6 ppb for bioallethrin in coho salmon to 80 ppb for s-bioallethrin in fathead minnows (5). The LC50 for allethrin in stoneflies is 5.6 ppb, and in black flies is 56 ppb (5).

The pyrethroid insecticides are extremely toxic to fish with 96-hour LC50 values generally below 10 ug/l. Corresponding LD50 values in mammals and birds are in the range of several hundred to several thousand mg/kg. Fish sensitivity to the pyrethroids may be explained by their relatively slow metabolism and elimination of these compounds. The half-lives for elimination of several pyrethroids by trout are all greater than 48 hours, while elimination half-lives for birds and mammals range from 6 to 12 hours (6).

Generally, the lethality of pyrethroids to fish increases with increasing octanol/water partition coefficients (8).

Effects on Other Animals (Nontarget species)

At normal application rates, allethrin is slightly toxic to bees (1, 5). Its LD50 is 3 to 9 ug/bee (4).


Breakdown of Chemical in Soil and Groundwater

No information was found.

Breakdown of Chemical in Surface Water

In pond waters and in laboratory degradation studies, pyrethroid concentrations decrease rapidly due to sorption to sediment, suspended particles and plants. Microbial and photodegradation also occur (7).

Breakdown of Chemical in Vegetation

No information was found.


Allethrin is a clear, amber-colored, viscous liquid (1) with a mild or slightly aromatic odor (5). It may decompose when exposed to heat or light and it is incompatible with alkalis (2).

Goggles, gloves and a respirator should be worn when handling technical allethrin or d-trans allethrin, or formulations that contain 90% or more of either active ingredient (1).

Exposure Guidelines:

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

Physical Properties:

CAS #: 584-79-2
Chemical Name: (2-methyl-1-propenyl)-2-methyl-4-oxo-3-(2 propenyl)-2-cyclo-penten-1-yl ester or mixture of cis- and trans-isomers (5).
Chemical Class/Use: Synthetic pyrethroid insecticide
Specific gravity: 1.005 -1.015
H20 solubility: allethrin and d-trans allethrin are insoluble in water (1, 2)
Solubility in other solvents: Miscible with most organic solvents at 20-25 degrees C (1); miscible with petroleum oils and soluble in paraffinic and aromatic hydrocarbons (5).
Boiling point: 320 degrees F (160 degrees C) (2)


Sumitomo Chemical Co., Ltd.
5-33, Kitahama 4-chome
Chuo-ku Osaka 541 Japan
Fax: 81-6-220-3492
Telex: 63823 SUMIKA J

Review by Basic Manufacturer:

Comments solicited: April, 1993
Comments received:

d-trans allethrin:
McLaughlin Gormley King Co.
8810 Tenth Ave. N.
Minneapolis MN 55427-4372

Review by Basic Manufacturer:

Comments solicited:
Comments received:


  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 Allethrin. OHS Inc., Secaucus, NJ.
  3. Herrera, A. and E. Laborda. 1988. Mutagenic activity in synthetic pyrethroids in Salmonella typhinurium. Mutagenesis 3 (6): 509-514.
  4. World Health Organization. 1989. Allethrins: allethrin, d-allethrin, bioallethrin, s-bioallethrin. IPCS Internat'l Programme on Chemical Safety, Environmental Health Criteria 87.
  5. U.S. Environmental Protection Agency. 24 March, 1988. Pesticide Fact Sheet Number 158: Allethrin Stereoisomers. US EPA, Office of Pesticide Programs, Registration Div., Washington, DC.
  6. Bradbury, S.P. and J.R. Coats. 1989. Toxicokinetics and toxicodynamics of pyrethroid insecticides in fish. Environmental Toxicology and Chemistry 8: 373-380.
  7. Muir, D.C.G., et al. 1985. Bioconcentration of cypermethrin, deltamethrin, fenvalerate and permethrin by Chironomus tentans larvae in sediment and water. Environmental Toxicology and Chemistry 4: 51-61.
  8. Haya, K. 1989. Toxicity of pyrethroid insecticides to fish. Environmental Toxicology and Chemistry 8: 381-391.