E X T O X N E T
Extension Toxicology Network
A Pesticide Information Project of Cooperative Extension Offices of
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University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Assessment Program.
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Pesticide
Information
Profile
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Fenoxycarb
Publication Date: 9/93
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TRADE OR OTHER NAMES
Trade names for products containing fenoxycarb include Insegar, Logic,
Pictyl, Torus and Varikill. Fenoxycarb is often formulated as a grit or
corncob bait.
INTRODUCTION
Fenoxycarb is a carbamate insect growth regulator. It is used as a
fire ant bait and for flea, mosquito and cockroach control. Fenoxycarb can
also be used to control butterflies and moths (Lepidoptera), scale insects,
and sucking insects on olives, vines, cotton and fruit. It is also used to
control these pests on stored products.
Fenoxycarb is a General Use Pesticide.
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
Fenoxycarb is a slightly toxic compound and carries the signal word
CAUTION on its label.
Fenoxycarb blocks the ability of an insect to change into an adult from
the juvenile stage (metamorphosis). It also interferes with the molting of
larvae. Insects have a rigid external covering called exoskeleton. In order
to grow and mature, insects must periodically shed or molt their old
exoskeleton and produce a new, larger one.
Fenoxycarb is nearly non-toxic to mammals. The oral LD50 of the
compound is greater than 16,800 mg/kg (1) in the rat. The dermal LD50 for
fenoxycarb in the rat is greater than 5,000 mg/kg. No deaths occurred at
this dose. When 5,000 mg/kg were administered to the animals' skin, rats
exhibited labored breathing, curved body position and diarrhea (1).
Fenoxycarb was not a skin sensitizer when tested on guinea pigs and has only
minimal eye irritation when applied to rabbits. The acute inhalation LC50 of
fenoxycarb in rats is greater than 480 mg/m3 showing the slightly toxic
nature of this substance by this route of exposure (3).
CHRONIC TOXICITY
Rats fed very low doses of fenoxycarb for a year had no compound
related effects at or below the 10 mg/kg/day dose. Dogs fed small amounts of
the compound for a month and a half experienced no adverse effects at or below
15.9 mg/kg/day (1). Similar results were noted for the compound in mice (1.4
mg/kg) and in rats (0.8 mg/kg) (3). Very few other studies have been
conducted on the chronic, long-term toxicity of the compound. Any adverse
effects above these feeding levels were not noted in the literature (3).
Reproductive Effects
No information was found.
Teratogenic Effects
With an unknown species, there were no teratogenic effects observed at
doses up to 300 mg/kg/day (1).
Mutagenic Effects
According to the Environmental Protection Agency, fenoxycarb is not
mutagenic. No additional information was available (1).
Carcinogenic Effects
No information was found.
Organ Toxicity
Rats that had small amounts of fenoxycarb applied to their skin for
twenty-one days had increased liver weights (1).
Fate in Humans and Animals
About ninety percent of a dose of fenoxycarb fed to rats was excreted
within 96 hours. No residues were found in the animals organs (1).
ECOLOGICAL EFFECTS
Fenoxycarb is practically non-toxic to birds (1). The compound has LD50s
greater than 3,000 mg/kg and 7,000 mg/kg in mallard ducks and bobwhite
quail, respectively. The dietary LC50 values for these species exceed
20,000 ppm. Duck and quail reproductive studies generated No-Observable-
Effect-Levels (NOEL) of 160 ppm and 400 ppm, respectively.
Fenoxycarb is considered moderately to highly toxic to fish with LC50s
ranging from 0.66 ppm for rainbow trout to 1.5 ppm for carp. Fish can
accumulate fenoxycarb in their bodies up to 300 times the concentration in the
water (1). Fenoxycarb is also considered highly toxic to Daphnia (LC50 = 0.6
ppm). However, under labeled use conditions the highest concentrations which
the compound should reach are far below (0.1% to 1.0%) the levels of concern
for acute toxicity to fish and invertebrates.
In one study, bluegill sunfish accumulated only twenty times the amount
of the compound's concentration in the water. Tissue residues of the
pesticide quickly declined after the fish were placed in pesticide-free water
(6). Therefore, the EPA has indicated that it is unlikely that the compound
would pose a threat to endangered aquatic organisms.
Fenoxycarb has demonstrated effects on the growth and reproduction of
Daphnia at extremely low levels during chronic laboratory studies (NOEL = 1.6
ppt). These long-term, constant exposure studies do not however, simulate
realistic exposures in the environment where degradation is rapid.
When fenoxycarb was applied at rates ranging from 0.015 to 0.03
lbs/acre to ponds, the compound had no effect on a number of different
invertebrates including cladocerans, copepods, ostracods and mayfly nymphs.
Specific concentrations in the water were not noted (4).
Fenoxycarb is practically non-toxic to bees in acute studies (Contact
LD50 > 100 ug/bee; Oral LD50 = 1,022 ppm, and Foliar LT50 > 24 hours). In a
worst case field trial with intentionally contaminated pollen (42.2 ppm) and
no alternative food source, a maximum of 10 percent pupae mortality was
observed. No effects on worker bees, egg laying or larvae development were
observed. Long-term effects were not observed.
ENVIRONMENTAL FATE
Fenoxycarb is readily broken down in soil by the chemical action of water
(hydrolysis). Residues in soil were no longer detectable three days after
application. The compound also has a low potential for leaching from the soil
and has a moderate to strong soil binding tendency (1). These characteristics
of fenoxycarb in soil indicate that it is unlikely to contaminate groundwater.
The compound is stable to hydrolysis in acidic water. It breaks downs
very rapidly in the presence of sunlight (photodegrades) in water. Half of
the initial amount of the compound is broken down by this means within five
hours (1). It readily attaches onto organic matter which may limit its
persistence in water. Residues in the water could be detected for only two
days following an aerial treatment of ponds for the control of mosquitoes (6).
Fenoxycarb is expected to break down relatively quickly in plants (3).
PHYSICAL PROPERTIES AND GUIDELINES
Exposure Guidelines:
No tolerances have been set.
Physical Properties:
| CAS #: | 79127-80-3 |
| Solubility in water: | 6 mg/l |
| Solubility in solvents: | hexane, 0.5/100 g; acetone, chloroform, diethylether, methanol 25 g/100 g |
| Melting point: | 53-54 degrees C |
| Vapor pressure: | 1.3 x 10-8 mmhg |
BASIC MANUFACTURER
Ciba-Geigy
Agricultural Division
P.O. Box 18300
Greensboro, NC 27419-8300
Telephone: 919-632-6000
FAX: 919-299-8318
Review by Basic Manufacturer:
Comments solicited: April, 1993
Comments received: May, 1993
REFERENCES
U.S. Environmental Protection Agency (1983-85). Chemical
Information
Fact Sheet. Office of Pesticides and Toxic Substances, Office of
Pesticide Programs (TS-766C).
Meister, Richard T. (ed.) 1992. Farm Chemicals Handbook. Meister
Publishing Company, Willoughby, OH.
The Agrochemicals Handbook. 1992. The Royal Society of Chemistry,
The University, Nottingham, England.
Miura, T., C.H. Schaefer and R.J. Stewart. 1986. Impact of
Carbamate
Insect Growth regulators on the Selected Aquatic Organisms; A Preliminary
Study. Proceedings Papers of the Annual Conference of the California
Mosquito Vector Control Association. Vol 54 36-38.
Miura, T. and R.M. Takahashi. 1987. Impact of Fenoxycarb, a
Carbamate Growth Regulator, On Some Aquatic Invertebrates abundant in
Mosquito Breeding Habitats. Journal of the American Mosquito Control
Association Vol 3: 476-480.
Schaefer, C.H., W.H. Wilder, F.S. Mulligan and E.E. Dupras. 1987.
Efficacy of Fenoxycarb Against Mosquitoes (Diptera: Culicidae) and its
Persistence in the Laboratory and Field. Journal of Economic Entomology
80(1): 126-130.
Disclaimer: Please read
the pesticide label prior to use. The information contained at this web
site is not a substitute for a pesticide label. Trade names used herein
are for convenience only; no endorsement of products is intended, nor is
criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
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