Cypermethrin - Chemical Fact Sheet 1/89
Name of Chemical: Cypermethrin
Reason for Issuance Registration Update
Date Issued: January 3, 1989
Fact Sheet Number: 199
1. DESCRIPTION OF CHEMICAL
Generic Name: (+/-)alpha-cyano-(3-phenoxyphenyl)methyl(+)-cis,trans-
propanecarboxylate* [containing 14% 1S-cis-S, 1R-cis-R,
1S-trans-S and 1R-trans-R and 11% 1R-cis-S, 1S-cis-R 1R-
trans-S and 1S-trans-R). . . .]
Common Name: Cypermethrin
Trade Names: Ammo; Cymbush; Demon; Cynoff
Other Names: Barricade; CCN52;
Cymperator; Cyperkill; Folcord; Kafil; Super; NRDC 149;
EPA Shaughnessy Code: 109702
Chemical Abstracts Service (CAS) Number: 66841-24-5
Year of Initial Registration: 1984
Pesticide Type: Pyrethroid-like; Insecticide/Miticide
Chemical Family: Pyrethroid
Manufacturers: FMC Corporation; ICI Americas, Inc.;
Shell International Chemical Company, Ltd.
2. USE PATTERNS AND FORMULATIONS
- Application Rates: Applied to cotton, lettuce (head) and pecans at a
rate up to 0.1 pounds active ingredient per acre. It may also be
applied into overhead sprinkler irrigation water. Cypermethrin is
also applied by Pest Control Operators as a crack, crevice, and spot
spray treatment in and around areas including, but not limited to,
stores, warehouses, industrial buildings, houses, apartment buildings,
greenhouses, laboratories, and on vessels, railcars, buses, trucks,
trailers, and aircraft.
- Also it may be used in nonfood areas of schools, nursing homes,
hospitals, restaurants, and hotels; and food manufacturing,
processing, and servicing establishments; as barrier treatments; and
as an insect repellent for horses and ponies.
- Usual Carrier: Water and oil
- Type of Formulations: 30.6, 25.3, and 36.6% emulsifiable concentrate
and 88 technical
- Registrations are being extended with an expiration date of
June 15, 1989. Tolerances expire December 31, 1989.
- RESTRICTED USE PESTICIDE - Extremely toxic to fish. For retail
sale to and use only by Certified Applicators, or persons under
their direct supervision, and only for those uses covered by the
Certified Applicator's Certification.
- REENTRY STATEMENTS - Do not treat areas while unprotected
humans or domestic animals are present in the treatment areas.
Do not allow entry into treated areas without protective clothing
until sprays have dried.
- Do not apply within 21 days of harvest.
- Do not graze livestock in treated orchards or cut treated cover
crops for feed.
- CROP ROTATION RESTRICTION - Do not plant rotational crops within
30 days of last application.
3. SCIENCE FINDINGS
Cypermethrin, a pyrethroid, is extremely toxic to fish. It is
highly toxic to bees exposed to direct treatment on blooming crops or
weeds. Cypermethrin has a low toxicity to mammals. EPA's review of
the cypermethrin pond study indicated that the data, as presented,
were not adequate or scientifically complete to allow the Agency to
evaluate the actual impact that the use of cypermethrin would have
an aquatic life forms. Therefore, ICI/FMC must repeat this study.
The EPA Peer Review Committee completed its evaluation of cypermethrin
with respect to its oncogenic potential and concluded that the data
available for cypermethrin provide limited evidence of oncogenicity
for the chemical in female mice. According to EPA Guidelines for
Carcinogen Risk Assessment (Federal Register September 24, 1986),
the Committee classified cypermethrin as a weak Category C oncogen
(possible human carcinogen with limited evidence of carcinogenicity
in animals). That is, cypermethrin produced benign lung adenomas at
the highest dose level in only one sex and species of animal (female
mice) and was not considered strong enough to warrant a "quantitative
estimation of human risk."
Chemical/Physical Characteristics of the Technical Grade:
- Physical State: Solid
- Color: Colorless crystals
- Odor: Odorless
- Molecular Weight: 416. 3
- Molecular Formula: C22H1903NC12
- Melting Point: 60 to 80 degrees C
- Boiling Point: 170 to 195 degrees C
- Density: 1.249 g CM3 at 20 degrees C
- Vapor Pressure: 8 x 10 to minus 4 at 80 degrees C; 1 x 10 to minus 7
at 20 degrees C
- Solubility in Various Solvents:
Water 4 ppb
Base as water
Acid as water
Propylene glycol insoluble ( less than 0.5%)
Methanol very soluble (approx. 75%)
Acetone completely miscible
Cyclohexanone completely miscible
Hexane slightly soluble (7%)
Xylene completely miscible
Methylene dichloride completely miscible
- Stability - as neat material: No detectable decomposition
at normal ambient temperatures
and for at least 3 months at
50 degrees C to date
- as dilute aqueous solution: Slowly hydrolyzes at
pH 7 and below. Hydrolyzes more rapidly at pH 9.
Slow photodegradation in sterile solution in sunlight
(< 10% in 32 days ) .
Toxicology Characteristics of the Technical Grade:
- Acute Oral LD50 - Rat: LD50 = 247 (187-326) mg/kg (males)
LD50 = 309 (150-500) mg/kg (females)
- Acute Dermal LD50 - Rabbit: LD5O > 2460 mg/kg
- Primary Dermal Irritation - Rabbit: PIS = 0.71
- Primary Eye Irritation - Rabbit: Mild irritation
- Skin Sensitization - Guinea Pig: May cause allergic skin reactions
- Subchronic Oral - Rat: NOEL of 75 ppm for pharmacological effects.
NOEL of 150 ppm for toxic effects.
- Chronic Toxicity - Rat: NOEL = 150 ppm
LEL = 500 ppm (HDT)
- Oncogenicity - 24-Month Mouse: Positive neoplastic response in lung
tissue. Increased incidence of benign adenomas in females (only),
statistically significant at 1600 ppm (HDT). No evidence of
oncogenicity in the rat at up to 1500 ppm (HDT).
- Teratogenicity - Rabbit: Not teratogenic at 30 mg/kg/day. (HDT).
- Rat: Not teratogenic at 70 mg/kg/day (HDT).
- Reproduction - 3-Generation Rat: NOEL for adverse reproductive
effects = 750 ppm (HDT), NOEL for systemic effects = 50 ppm, LEL = 150
ppm (decreased body weight gain in maturing pups).
- Mutagenicity - Ames Test: Not mutagenic.
- Mutagenesis - Host-Mediated Assay: Not mutagenic at 50 mg/kg.
- Mutagenesis - Dominant Lethal: Not mutagenic at 25 mg/kg.
Physiological and Biochemical Characteristics:
- The mode of action in biological systems is stomach and contact
exhibiting neurotoxicological characteristics typical of pyrethroid
insecticides. Slight repellent effect.
- Foliar Absorption - N/A.
- Translocation - N/A.
- Adequate data are sufficient to define the fate of cypermethrin in
the environment. Cypermethrin is stable to hydrolysis, with an
estimated T 1/2 exceeding 50 days at environmentally expected
temperatures and pH values. Cypermethrin is extremely stable to
photolysis in water with an estimated T 1/2 exceeding 100 days at
environmentally expected temperatures and pH values. Photo products
produced included DCVA, 3-phenoxybenzaldehyde, and 3-phenoxybenzoic
acid. Cypermethrin photodegrades rapidly on soil surfaces (T 1/2:
8 to 16 days) to many photo products, the major ones identified as
3-phenoxybenzoic acid and compound XIV. Cypermethrin degrades in
soil under laboratory conditions. The rate is more rapid on
sandy clay and sandy loam soils than on clay soils and more rapid
on soils lower in organic matter content and cation exchange
capacity under all aerobic conditions. The T 1/2 in aerobic soils
ranged from 2 to 8 weeks. In sterile aerobic soils,
cypermethrin degraded with a T 1/2 of 20 to 25 weeks indicating
that microbes play a significant role in soil degradation.
Cypermethrin degraded more slowly under anaerobic or waterlogged
conditions with the major metabolite 3-phenoxybenzoic acid produced.
Under aerobic conditions the major metabolites produced were DCVA
and 3-phenoxybenzoic acid. Cypermethrin does not leach signifi-
cantly in soil. It has a low solubility in water (0.2 ppm) and,
consequently, high adsorption characteristics. The leaching
potential for its degradates may be higher. Under field conditions,
runoff of cypermethrin has been shown to occur to some degree and
was probably due to physical transport of the solid particles via
erosion. Cypermethrin itself degrades rapidly in the field with
a T 1/2 of 4 to 12 days. The persistence of the major aerobic
soil metabolites is not known. Both accumulation and depuration
of cypermethrin residues will occur in trout and catfish. Bio-
concentration factors of approximately 1200X were calculated in
rainbow trout in a flowthrough study. The data requirement for
accumulation of cypermethrin in rotational crops has not been
Ecological Effects Characteristics:
- Avian acute oral LD50 - Mallard Duck: > 4640 mg/kg
- Avian dietary LC50 - Mallard Duck and Bobwhite Quail:
LC50 > 20,000 ppm
- Avian reproduction - Mallard Duck and Bobwhite Quail:
NOEL > 50 ppm (HDT)
- Fish acute 96-hour LC50 - Rainbow Trout = 0.82 ppb
- Fish acute 96-hour LC50 - Bluegill Sunfish = 1.78 ppb
- Aquatic invertebrate acute LC50 - Daphnia magna = 0.26 ppb
- Section 408 tolerances under the Federal Food, Drug, and Cosmetic Act
are established until December 31, 1989 for residues of the
insecticide cypermethrin [(+/-)alpha-cyano-(3-phenoxyphenyl)
methyl (+-cis,trans-3-(2,2-dichloroethenyl)-2 panecarboxylate]
and its metabolites* 3-PB Acid and DCVA in or on the following
raw agricultural commodities:
Cattle, fat 0.05
Cattle, meat 0.05
Cattle, meat byproducts 0.05
Goats, fat 0.05
Goats, meat 0.05
Goats, meat byproducts 0.05
Hogs, fat 0.05
Hogs, meat 0.05
Hogs, meat byproducts 0.05
Horses, fat 0.05
Horses, meat 0.05
Horses, meat byproducts 0.05
Lettuce (head) 10.00
Sheep, fat 0.05
Sheep, meat 0.05
Sheep, meat byproducts 0.05
- The acceptable daily intake (ADI) is calculated to be 0.01 mg/kg/day
based on a dog study with a NOEL of 1.0 mg/kg/day and using a
safety factor of 100. The maximum permissible intake (MPI) is
calculated to be 0.60 mg/kg/day for a 60-kg person. Published
tolerances result in a theoretical maximum residue contribution
(TMRC) of 0.002773 mg/kg bwt/day. The existing TMRC is equivalent
to 27.7 percent of the ADI. No additional data are required to
support the current crop tolerances listed in 40 CFR 180.418.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Adequate data are available to assess the acute and chronic
toxicological effects of cypermethrin to humans. The Agency's review
of the field study (S72-7) found that the data, as presented, were not
scientifically adequate nor sufficiently complete to allow the Agency
to evaluate the actual impact that the use of cypermethrin would have
on aquatic life forms. ICI/FMC disagreed with the Agency's conclusion
and will submit additional information necessary in order for the
Agency to complete the risk assessment.
- On the basis of this information, EPA seriously considered whether to
issue new conditional registrations for cypermethrin. Based on the
information submitted, on January 3, 1989 the Agency issued new
conditional registrations of cypermethrin which will expire on
June 15, 1989.
- The Agency issued these new conditional registrations for this short
period of time to ICI and FMC in light of their agreement to:
a. Submit all data generated in the course of the cypermethrin
Alabama pond study pertaining to runoff and residues in water
and sediment to the Agency by January 1989.
b. Submit all other data now in existence and not previously
submitted to the Agency, as well as all other data generated
in the future in the course of the cypermethrin Alabama pond
study, as soon as is practical.
c. Conduct an aquatic mesocosm study (a simulated 2-year field
study) for which EPA will develop and provide the protocol no
later than April 15, 1989, in case ICI/FMC do not persuade
EPA that the current cypermethrin pond study is acceptable.
d. Within 30 days of receipt of an EPA protocol for an aquatic
mesocosm study, provide the Agency with written unconditional
acceptance of the protocol and an unconditional commitment to
conduct the study through completion. For any modification
of the protocol to be valid, it must be agreed to by EPA
within the above-mentioned 30-day period.
- EPA has concluded that the continual use of cypermethrin for this
short period of time will not cause a significant increase in the risk
of adverse effects to the environment.
- The Delaney Clause in section 409 of the Federal Food, Drug, and
Cosmetic Act bars the establishment of food additive regulations for
substances which induce cancer in man or test animals. Since
cypermethrin has been found to produce an oncogenic response in test
animals, no 409 tolerances will be granted. Cypermethrin as parent
does not leach significantly in soil. At this time, there are no
concerns for ground water contamination.
5. SUMMARY OF MAJOR DATA GAPS
- Simulated and/or actual field study (Section 72-7)
6. CONTACT PERSON AT EPA
George T. LaRocca
Product Manager (15)
Registration Division (H7504C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street SW.
Washington, DC 20460
Office location and telephone number:
Room 211, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202
Phone: (703) 557-2400
DISCLAIMER: The information presented in this Pesticide Fact Sheet is
for informational purposes only and may not be used to fulfill data
requirements for pesticide registration and reregistration.