E X T O X N E T
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
TRADE OR OTHER NAMES: Cyfluthrin is the active
ingredient in many insecticide products including Baythroid, Baythroid H,
Attatox, Contur, Laser, Responsar, Solfac, Tempo and Tempo H. Combination
products include Baythroid TM (+ methamidophos) and Aztec (+ tebupirimphos)
REGULATORY STATUS: First registered by EPA in 1987,
cyfluthrin is found in both restricted use (RUP) and general use insecticides
(70). Cyfluthrin containing products may be classified by EPA as acute Toxicity
Category II (bearing the signal word "Warning") or Toxicity Category I (bearing
the signal word "Danger") based on its potential to cause eye damage (69).
Currently, there are tolerances for residues of cyfluthrin in or on raw
agricultural products ranging from 0.05 (hog meat) to 4.0 ppm (hops) (71). Note:
These are subject to change. Check with specific state regulations for local
restrictions which may apply.
INTRODUCTION: Cyfluthrin is a synthetic pyrethroid
insecticide that has both contact and stomach poison action. It is a
non-systemic chemical used to control cutworms, ants, silverfish, cockroaches,
termites, grain beetles, weevils, mosquitoes, fleas, flies, corn earworms,
tobacco budworm, codling moth, European corn borer, cabbageworm, loopers,
armyworms, boll weevil, alfalfa weevil, Colorado potato beetle, and many others.
Its primary agricultural uses have been for control of chewing and sucking
insects on crops such as cotton, turf, ornamentals, hops, cereal, corn,
deciduous fruit, peanuts, potatoes, and other vegetables. Cyfluthrin is also
used in public health situations and for structural pest control (72).
FORMULATIONS: Cyfluthrin based insecticide
formulations are available in the form of emulsifiable concentrates, wettable
powder, aerosol, granules, liquid, oil-in-water emulsion and ULV oilspray (69).
Typical application rates for agricultural use range from 0.0125 - 0.05
pounds/acre, substantially lower than many other commonly used insecticides.
Pyrethrin and pyrethroid formulations typically contain piperonyl butoxide which
acts as a chemical synergist. Typical carriers include organic solvents and
water. It is incompatible with azocyclotin.
- Acute Toxicity: Cyfluthrin is considered moderately toxic
to mammals. The oral dose of cyfluthrin that resulted in mortality to half of
the test animals (LD50) ranged from 869 - 1271 mg/kg in rats, 291 - 609 mg/kg
in mice, >1000 mg/kg in sheep, > 100 mg/kg in dogs and > 1000 mg/kg
in rabbits (74). In inhalation toxicity tests with rats, the concentration of
cyfluthrin in air that resulted in mortality to half of the test animals
(LC50) was >1,089 ug/l in 1 hour tests, and ranged from 469 - 592 ug/l in 4
hour tests (74). Although cyfluthrin is an irritant to human skin, especially
facial skin, it is not considered to have high dermal toxicity. The dermal
LD50 in tests with rats was > 5,000 mg/kg, and was not found to be a skin
irritant or sensitizer in guinea pigs and rabbits (73, 74).
- Signs and Symptoms of Acute Poisoning: Although
cyfluthrin is a skin and eye irritant in humans, pyrethroid poisonings are
rare. The main reason for their low toxicity in humans, is that they are
rapidly broken down in the human body by liver proteins, and eliminated fairly
quickly (see fate in humans and animals section). Also, pyrethroids are not
well absorbed into the bloodstream, contributing to their moderate acute
toxicity in mammals. In laboratory tests where animals have been exposed to
very large doses of pyrethroids orally or by injection, there have been
effects on the nervous system. Symptoms of acute poisoning include
irritability, excessive salivation, uncoordinated gait, tremors, convulsions,
and death. Cyfluthrin may cause itching, burning, or stinging if it comes in
contact with human skin.These sensations can progress to a numbing effect that
may last up to 24 hours. Usually, there is a 1-2 hour delay of skin irritation
following exposure, but it may occur immediately. Dermal irritation may be
worsened by sweating, exposure to sun or heat and application of water(75).
- Chronic Toxicity: Long-term feeding studies have been
conducted with mice, rats and dogs. Invest-igations of blood chemistry, and
necropsies of vital organs did not indicate any organ specific toxicity. The
only long-term effects of exposure to cyfluthrin were the retardation of
weight gain, and changes in some organ weights associated with body weight
effects in the high dose groups (74). In a two-year feeding study with rats
fed up to 450 ppm Baythroid, decreased body weights were observed in males,
and some inflamation of the kidney was observed in females (76).
- Reproductive Effects: A three generation reproductive
study in rats produced a systemic No Observable Effect Level (NOEL) of 50 ppm
(2 mg/kg/day), and a Low Observable Effect Level (LOEL) of 150 ppm (7.5
mg/kg/day) based on decreased body weights in pups. It was also determined
that the NOEL and LOEL for viability of offspring were 50 ppm and 150 ppm,
- Teratogenicity Effects: A developmental toxicity study in
rats given doses of up to 30 mg/kg cyfluthrin over days 6-15 of gestation
resulted in a maternal NOEL of 3 mg/kg/day based on behavioral changes in gait
and coordination, and a teratogenic NOEL of 30 mg/kg/day (highest dose
tested). Another study in rabbits resulted in a maternal NOEL of 15 mg/kg/day
based on fetal abortion and resorption. No developmental abnormalities were
observed at the highest dose tested of 45 mg/kg/day (76).
- Carcinogenic Effects: There was no evidence of
carcinogenicity in rats or mice.
- Mutagenic Effects: Cyfluthrin was negative for
- Organ Toxicity: Short and long term studies of the
effects of cyfluthrin on mammalian systems have resulted in pockets of
inflamation in the kidneys of females, and reversible damage to the sciatic
nerve (this nerve controls sensation in the leg)(74).
- Fate in Humans and Animals: Cyfluthrin metabolism in
mammals occurs in two phases (biphasic), an initial fast phase, and a slower
second phase. Laboratory tests show that about 60% of an intravenous dose of
cyfluthrin is eliminated in the urine in the first 24 hours, with only an
additional 6% eliminated in the next 24 hours. Similarly, 20% of the
administered dose was eliminated in the feces in the first day, followed by
3-4% the next day. Another test with a single oral dose of cyfluthrin showed
that 98% of the material was eliminated by 48 hours (74).
- Effects on Birds: Cyfluthrin is of low toxicity to upland
game birds and waterfowl. LD50 values range from >2,000 mg/kg in acute oral
tests with bobwhite quail, to >5,000 mg/kg in subacute tests with both
mallard ducks and bobwhite quail (70). Other tests with chicken hens have
resulted in LD50 values of 4,500 - >5,000 mg/kg depending on the vehicle of
administration (74). Little information was found concerning the toxicity of
cyfluthrin to songbirds. LD50 values for canaries range from 250-1000 mg/kg
- Effects on Aquatic Organisms: Cyfluthrin is highly toxic
to marine and freshwater organisms. The concentration of cyfluthrin in water
that resulted in the mortality of half of the test organisms (LC50) was
0.00068 mg/l in rainbow trout, 0.0015 mg/l in bluegill, 0.022 mg/l in carp,
and 0.0032 mg/l in golden orfe (70, 73). Cyfluthrin is exceptionally toxic to
the freshwater invertebrate Daphnia magna, (LC50 = 0.14 ng/l or .00000014
mg/l). Marine and estuarine invertebrates are also extremely sensitive to
cyfluthrin. The LC50 for mysid shrimp was 2.42 ng/l and the EC50 for the
eastern oyster was 3.2 ng/l. The LC50 for the sheepshead minnow was 0.004 mg/l
- Effects on Other Animals (Nontaret species): Cyfluthrin
is highly toxic to bees with an LD50 of 0.037 mg/bee (70). Pyrethroids are
known to be highly toxic to other beneficial insects.
- Breakdown of Chemical in Soil and Groundwater: Cyfluthrin
is sensitive to breakdown by sunlight. On the surface of soils, its half-life
is 48-72 hours. It has a half-life of 56-63 days in German loam and sandy loam
soils, respectively, and has similar persistence in soils under conditions of
low oxygen (anaerobic). Cyfluthrin is very immobile in soils, and is not
considered a threat to contaminate groundwater (77). The primary breakdown
products of cyfluthrin are carbon dioxide and 4-fluoro-3-phenyl-benzaldehyde
(a compound of considerably lower toxicity than the parent compound) (70).
- Breakdown of Chemical in Surface Water: Cyfluthrin is
broken down quickly in surface water. Beacuse it is realtively non-soluble,
and less dense than water, it will float on the surface film of natural
waters. At the surface, it is subject to breakdown by exposure to sunlight (1
day). It is stable to breakdown by water at acidic pH, and quickly hydrolyzed
in water under basic conditions (77).
- Breakdown of Chemical in Vegetation: There is little
information available about the breakdown of cyfluthrin in vegetation. One
study determined that very small amounts of cyfluthrin residues remained on
strawberries 7 days after the last of 3 weekly applications (78). Another
researcher identified a protein in tomatoes that is capable of breaking down
cyfluthrin (79). Researchers in Australia demonstrated that cyfluthrin is
stable and resistant to breakdown when used on wheat in storage for up to 52
PHYSICAL PROPERTIES AND GUIDELINES
- Appearance: pasty yellow mass
- Chemical Name:
- CAS Number: 68359-37-5
- Molecular Weight: 434.3
- Water Solubility: 0.002 mg/ml @ 20 degrees C.
- Solubility in Other Solvents: > 200 g/l in
dichloromethane and toluene, 10-20 g/l hexane, 20-50 g/l propan-2-ol
- Melting Point: Not Available
- Vapor Pressure: 1.62 x 10 to the minus 8 mmHg
- Partition Coefficient: Not Available
- Adsorption Coefficient: 5.62
- ADI: 0.02 mg/kg b.w.
- MCL:Not Available
- RFD: 0.025 mg/kg/day
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
Bayer Agricultural Products
PO Box 4913
Kansas City, MO 64120
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 label/ing or other regulatory requirements. Please refer to the
pesticide product label/ing.