E X T O X N E T
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
Publication Date: 9/93
TRADE OR OTHER NAMES
Some trade names include AC 222705, Cybolt and Pay-Off (discontinued).
Some applications of flucythrinate may be classified as Restricted Use
Pesticides (RUP) by the EPA (1). Restricted Use Pesticides may be purchased
and used only by certified applicators. Pesticides containing flucythrinate
must bear the signal word "Danger" on the product label (1) because of this
active ingredient's potential to cause eye irritation and because of its high
oral toxicity (3).
Flucythrinate is a synthetic pyrethroid used to control insect pests in
apples, cabbage, field corn, head lettuce and pears, and to control Heliothis
spp. in cotton (1). It is used primarily on cotton (3). It is available in
emulsifiable concentrate and wettable powder formulations (1).
Flucythrinate is a highly toxic pesticide (1). Rats fed 15 mg/kg/day for
28 days showed severe motor symptoms (involuntary muscular movement), and rats
fed 7.5 mg/kg/day showed moderate motor symptoms. In both cases, symptoms
disappeared within 48 hours after resumption of a normal diet (2). Symptoms
exhibited by animals in short-term feeding studies include vomiting,
diarrhea, incoordination, excessive salivation and urination, and
Flucythrinate can cause extreme eye irritation (3) and mild to severe
skin irritation (12). It failed to produce allergic reactions in guinea pigs
(3, 12). When 130 ug/cm2 was applied to the ear lobes of human volunteers,
flucythrinate caused severe paresthesia (i.e. abnormal sensations such as
burning or tingling) which began 30 minutes after the application and
continued for 24 hours. Of four pyrethroids tested in this way, flucythrinate
produced the most severe paresthesia (2). Skin on the forearm proved to be
less sensitive than the earlobes. When 13.8 mg/cm2 was applied to the
forearms of volunteers, paresthesia appeared 4 to 5 hours later and lasted for
3 days (2).
In a 21-day delayed neurotoxicity study with hens, the NOEL was 5,000
mg/kg, the highest dose tested (5).
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 oral LD50 for technical flucythrinate in male rats is 81 mg/kg
(5), 67 mg/kg in female rats (1, 2), and 76 mg/kg in mice (2). The dermal
LD50 in rabbits is >1,000 mg/kg (1), and on guinea pigs is >2,000 mg/kg (3).
The 4-hour inhalation LC50 for technical flucythrinate in rats is 0.064 mg/l
No adverse effects were observed when rats and dogs were fed
flucythrinate for 90 days at doses of up to 3 mg/kg for rats and 3.75 mg/kg
for dogs (5). Dogs fed 7.5 mg/kg/day for 2 years exhibited vomiting and
decreased body weight gain. The NOEL for this study was 0.75 mg/kg/day (12).
Rats fed 6 mg/kg/day for 2 years also exhibited decreased body weight gain.
The systemic NOEL for this study was 3 mg/kg/day (12).
In a 3-generation reproductive study, rats given 1.5, 3 or 6 mg/kg doses
showed reduced parental and pup weights, and decreased pup survival. Reduced
litter size occurred at 3 and 6 mg/kg. The NOEL was 1.5 mg/kg (5, 12).
Flucythrinate does not cause birth defects (2). No teratological
effects were observed in studies with rats or rabbits. The highest dose
tested was 8.0 mg/kg/day for rats and 60 mg/kg/day for rabbits (5).
Flucythrinate is not mutagenic (2). An Ames test using several strains
of bacteria exposed to concentrations as high as 1,000 micrograms (ug)/plate
and a rat dominant-lethal test at up to 10.0 mg/kg both showed no evidence
that flucythrinate causes mutations (5, 12).
No tumor formation was observed in mice or rats fed doses of up to 6
mg/kg for 24 months (5, 12).
Pyrethroids may cause adverse effects on the central nervous system.
Long-term feeding studies have shown increased liver and kidney weights and
adverse changes in liver tissues in test animals (9).
Fate in Humans and Animals
Flucythrinate is rapidly metabolized by ester cleavage and oxidation (2).
When radio-labeled flucythrinate was administered orally to rats, 15 to 24%
was eliminated in the urine and 37 to 65.6% was eliminated in the feces during
the first 24 hours. Within 8 days, 95.8 to 100% of the dose was eliminated in
either urine or feces. A large amount of the chemical recovered in the feces
was unaltered flucythrinate, suggesting that this portion passed through the
gut without being absorbed into the bloodstream (3). Metabolites of
flucythrinate are considered to be of no toxicological significance (12).
Effects on Birds
Pyrethroids are practically non-toxic to bird species.
Effects on Aquatic Organisms
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 (9).
Flucythrinate accumulated in the edible tissues of bluegill sunfish to
487 times the concentration in surrounding waters (11).
Generally, the lethality of pyrethroids to fish increases with
increasing octanol/water partition coefficients (10).
Effects on Other Animals (Nontarget species)
No information was found.
Breakdown of Chemical in Soil and Groundwater
Flucythrinate is nearly insoluble in water and it has a strong tendency
to bind to soil particles. It is therefore unlikely to contaminate
groundwater (6). A soil half-life of 21 days has been reported (6).
When applied to a sandy loam soil, 80% of the parent compound was
recovered after 2 months, indicating that flucythrinate decomposes slowly in
soil. The only degradate found at the end of 2 months was m-phenoxy benzoic
acid (11). In field soils, dissipation occurred within 2.2 months, with most
residues found within the top 3 inches of soil (11).
Following multiple applications to sand, clay and loam soils, there was
no accumulation of flucythrinate in the upper 6 inches of soil. Residues
were found in the upper 3 inches of soil from 47 to 50 days following
Barley, snapbeans and beets grown in the greenhouse contained residues of
less than 0.01 ppm after application of 0.05 pounds of flucythrinate per acre.
No residues were found in treated crops grown in the field (11).
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 (8).
Breakdown of Chemical in Vegetation
No information was found.
PHYSICAL PROPERTIES AND GUIDELINES
Flucythrinate is a dark amber, viscous liquid. It is stable in neutral
and acidic conditions (1, 3) and it is stable in light (2).
Because this compound is an eye irritant, workers handling
flucythrinate should wear goggles or a face shield (1).
No occupational exposure limits have been established for flucythrinate
by OSHA, NIOSH or ACGIH (7).
|ADI: ||0.025 mg/kg/day, based on a NOEL of 2.5 mg/kg in a 2-year rat feeding study and a safety factor of 100 (4).
|CAS #: ||70124-77-5
|Chemical Name: ||alpha-Cyano-3-phenoxybenzyl-(S)-2-[4-(di-fluoromethoxy)phenyl]-3-methylbutyrate (2)
|Chemical Class/Use: ||Synthetic pyrethroid insecticide
|Density: ||1.19 gm/ml at 22 degrees C (2)
|H20 solubility: ||0.5 ppm at 21 degrees C; 0.48 ppm at 25 degrees C (1, 3)
|Solubility in other solvents: ||soluble in most organic solvents (1); soluble in acetone, xylene and isopropanol (3).
|Boiling point: ||108 degrees C at 0.35 mm Hg (3)
|Vapor pressure: ||8.7 x 10-9 mm Hg at 25 degrees C (2, 6); 2.4 x 10-7 mm Hg at 45 degrees C (3)
|Koc: ||100,000 gm/ml (6)
DuPont Agricultural Products
Barley Mill Plaza
P.O. Box 80038
Wilmington, DE 19880-0038
Review by Basic Manufacturer:
Comments solicited: June, 1993
Meister, R.T. (ed.). 1992. Farm Chemicals Handbook '92. Meister
Publishing Company, Willoughby, OH.
Hayes, W.J. and E.R. Laws (eds.). 1990. Handbook of Pesticide
Toxicology, Classes of Pesticides, Vol. 2. Academic Press, Inc., NY.
Mehler, L.N. 1989 (March 17). Assessment of Human Exposure to
Flucythrinate, HS-1510. California Department of Food and Agriculture,
U.S. Environmental Protection Agency. Jan. 25, 1988. Pesticide
tolerances for cyano(4-fluoro-3-phenoxyphenyl)methyl 3-(2,2-
Register, 53 (15): 1916-7.
_____. May 22, 1985. Pesticide tolerance on an agricultural
commodity; flucythrinate. Federal Register, 50 (99): 21050-1.
U. S. Department of Agriculture, Soil Conservation Service. 1990
(Nov.). SCS/ARS/CES Pesticide Properties Database: Version 2.0
(Summary). USDA - Soil Conservation Service, Syracuse, NY.
Occupational Health Services, Inc. 1993 (Nov. 17). MSDS for
Resmethrin. OHS Inc., Secaucus, NJ.
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.
Bradbury, S.P. and J.R. Coats. 1989. Toxicokinetics and
toxicodynamics of pyrethroid insecticides in fish. Environmental
Toxicology and Chemistry 8: 373-380.
Haya, K. 1989. Toxicity of pyrethroid insecticides to fish.
Environmental Toxicology and Chemistry 8: 381-391.
US Environmental Protection Agency. Sept. 27, 1989. Pesticide
Environmental Fate One Line Summary. Environmental Fate and Effects
Division, US EPA, Washington, DC.
US Environmental Protection Agency. Nov. 15, 1989. Tox Oneliners:
Pay-off. Office of Pesticides/HED/SACB, US EPA, Washington, DC.