United States
Environmental Protection
Agency
Office of Pesticides and Toxic Substances
Office of Pesticide Programs (TS-766C)
Washington, DC 20460
&EPA Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuance:
Date Issued: 2/88
Fact Sheet Number:
FenoXaprop—e thyl
New Chemical Registration
157
DESCRIPTION OF CHEMICAL
Generic Name:
Common Name:
Trade Names:
EPA Shaughnessy. Code:
Chemical Abstracts
Service (CAS) Number:
year of Initial
Registration:
Pesticide Type:
Chemical Family:
Producer:
(j+O ethyl 2-[4-(6-chloro-2-
benzoxazo ly Do xy 1 pheno xy 1 propanoa t e
Fenoxaprop-ethy1
Whip, Acclaim
12R701
66441-23-4
1987
Herbicide
Structurally related to
diphenyl ethers
American Hoechst Corporation
2. USE PATTERNS AND FORMULATIONS
Application sites; Used for post-emergent control of annual
and perennial grasses* on terrestrial and aquatic food crops
(rice and soybeans) and on terrestrial nonfood and domestic
outdoor use sites (turfgrass, including sod farms, rights-
of-way, and commercial and residential turf).
Types of formulations; 93* active ingredient technical grade. •
End use products containing 12.50% active ingredient formulated
as emulsifiable concentrates.
r
Usual carrier; Water. Non-phytotoxic crop oil may also be
used with the agricultural use formulation.
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Types and methods of application : Fenoxaprop-ethyl is appliec
to turfgrass by pressurized hydraulic sprayers (30—60 PSI)
and hand held pump sprayers. It may also be applied as a
spot treatment. Both ground and •aerial appl cat1on are
permItted for the use on soybeans and rice.
Application rates : ApplIcation rates for soybeans range from
.8 to 1.2 pints per acre (.10 to .15 pounds actIve ingredient)
depending on the target weed species. For rice, application
rates vary from 1.2 to 1.6 pints per acre (.15 to .20 pounds
active Ingredient) dependIng on the target weed species and
stage of growth. Application rates for turfgrass range from
15 to I5 fluid ounces per acre and from .15 to 1.02 flUid
ounces per 1,000 square feet .depending on th type of
turf and stage of weed growth.
3. SCIENCE FINDINGS
Summary Science Statement : Fenoxyprop—ethyl induces
developmental toxicity (birth defects) ifl rabbits based
on studies which showed that dietary administration of
the compound caused an Increased incidence of rib anomalIes and
diaphragmatlc hernias at 200 mg/kg, the highest dose tested.
Margins of safety (MOs) calculated based on a no—observed—
effect—level of 50 mg/kg in the rabbit study are Vi0,000
and 260,000 for one serving daily of rice and soybean Oil,
respectively. Even assuming that four servings of each
could be consumed every day, the MOS’s would be 180,000
for rice and 66,000 for soybean oil. MOS values for
mixer/loaders are 1,250,000, for Inhalation exposure,
and 1000, for dermal exposure. For applicators, the
MOS for inhalation exposure is 250,000; the MOS for
dermal exposure Is 2500. In addition, the label requires
that mixer/loaders wear protective clothing, Including
impermeable gloves, and long—sleeved shirts and pants.
Applicators must also wear long—sleeved shIrts and pants.
The teratogenic risk to consumers of foods treated with -
fenoxaprop—ethyl and to users of the herbIcide are therefore
quIte low.
Fenoxaprop-ethyl did not Induce an oncogenic response in long—
term rat and mouse studies. The chemical dId not signifIcantly
Impair reproductive abilIty Ifl a two—generation reproductive
effects study in rats. Four mutagenicity studies with
fenoxaprop—ethyl were negative.
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In both short and long term animal studies, fenoxaprop—
ethyl induced tox colog1cally significant increases and
decreases in lipid enzymes (blood cholesterol). The Agency
has calculated MOS values for these effects based on
the highest dose tested, 6 mg/kg, In a mouse oncogenicity
study, the mouse being the most sensitive specIes. The
dietary MOS values are, for rice, 35,000, and for soybean
Oil, 31,000. For applIcators, MOS values are 30,000 for
inhalation exposure and 300 for dermal exposure. For
mixers/loaders, the MOS for inhalatIon exposure is 150,000
and 120 for derrnal exposure. The dermal exposure MOS’s
were calculated based on exposure estimations which assumed
that 100% of the chemical would be absorbed through the skin.
However, as Indicated above, mixer/loaders/applicators are
requIred to wear protective clothing, and therefore exposure
wIll be reduced.
Fenoxaprop—ethyl is not acutely toxic to humans or avian
species. The pesticide Is toxic to fIsh and aquatic invertebrates
Environmental fate studIes show that fenoxaprop—ethyl does
not persist signifIcantly in the environment, that it is
relatively immobile and therefore should not pose a risk of
leaching to groundwater.
Chemical CharacteristIcs :
PhysIcal state: brown crystalline solid
Molecular formula: - C 18 H 16 C1N0 5
Molecular weight: 361.8 g/M
Solublilty: 0.9 mg/i (pH 7 at 25°C) In water,
low solubility
Melting point: 85—87°C
Vapor pressure: 0.187 x 10—7 mbar at 20°C
(non volatile)
Toxicological characteristics :
Acute oral toxicIty (rat): 2357 mg/kg
(relatively nontoxlc)
Acute dermal toxIc ty (rat) Greater than 2000 mg/kg
(mo’ erately toxIc)
Acute derinal toxicity (rabbIt): Greater than 2000 mg/kg
(moderately toxIc)
Dermal sensitIzatIon: Non—sensitizing
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Chronic effects :
2-generation Reproduction (rat): NOEL = 5 ppm (0.25 mg/kg)
based on reduced blood lipI
in parents and reduced body
we .ght in offspring
Developmental Tox .city: RabbIt —- NOEL = 12.5 mg/kg..
for maternal toxicity, based
on decreased food consumption
and weight gain; NOEL = 50 mg/kg
for developmental effects, based
on increased Incidence of rib
anomalies and diaphragmatlc
hernia; teratogenic
Rat -- NOEL = 32 mg/kg for
maternal toxicity based on
reduced body weight ga n;
NOEL = 32 mg/kg for developmenta
(fetotoxlc) effects —— delayed
ossification and slightly -
impaIred growth; NOEL =
100 mg/kg for teratogenic effect
ChronIc Feeding/
Oncogenicity: Rat —— not oncogenic at
doses up to and including
180 ppom (9 mg/kg);
systemic toxicity NOEL =
30 ppm (1.5 mg/kg) based
on decreased serum cholesterol
Mouse —— not oncogenic at
doses up to and including
140 ppm (6 mg/kg); dosing
not adequate to achieve
a maximum tolerated dose (MTD) —-
Adequate MOS values based on
ratio of highest dose tested/
maximum daily dietary intake.
Dog —— NOEL = 15 ppm (0.37
mg/kg) based on reduced
body weight
Mutagenicity: NegatIve —— chromosomal
aberratIon, Ames test,
Unscheduled DNA Synthesis,
and mouse mIcronucleus
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Physiological and biochemIcal behavior characteristIcs:
Mode of Activity : Fenoxaprop-ethyl Is a systemic herbicIde
which Is rapidly absorbed and translocated throughout
leaf and stem tissue. Although the precise mode of activity
is unknown, fenoxaprop—ethyl Is thought to kill weeds by
disrupting lipid metabolism. Effects are seen as general
yellowing of the weed followed by death in approximately
two to three weeks.
Trans].ocation characteristics : Fenoxaprop—ethyl Is hIghly
systemIc and rapidly metabolized and therefore there Is
lIttle potentIal for the presence of residues ifl the
edible parts of crops treated with the herbIcide.
Environmental characteristIcs: Fenoxaprop-ethyl is stable
to hydrolysis at 20°C in p115 and p117 olUtiOflS, but
rapidly hydrolyzes in p119 solutions. Extensive environmental
fate studies show that the chemical does not persist significantly
in any medIum. Residues In irrIgated and rotational
crops will not be detectable when label restrictIons on using
water from rice fields to irrigate grops and on planting
rotational crops are strictly followed. Fenoxaprop—ethyl
was slightly mobile in two loamy sand soils, two silt loam
soils and an aquatic sediment (clay). Therefore, there is
little potentIal that fenoxaprop—ethyl would leach to
ground water.
Ecological characteristics :
Avian Reproduction: Bobwhite —— 30 ppm
Mallard duck -- 180 ppm
(NOEL’s for reproductIve
effects; does not impair
avian reproduction)
Avian Oral toxicity: Bobwhite quail -— >2510 mg/kg
Avlan dietary toxicity: Mallard duck —— >5620 mg/kg
BobwhIte quail -- >5620 mg/kg
Freshwater fish: Bluegill —— 310 ppb
Pumpklnseed sunfish -- 360 ppb
Brown trout -— i8o ppb
Aquatic Invertebrates: Daphnia Magna —— 3.18 ppm
These data Indicate that fenoxaprop—ethyl IS essentially
non—toxic to avlan species and that It does not Impair
avian reproduction; and that fenoxaprop—ethyl is acutely
toxic to fIsh and aquatic Invertebrates. The label prohIbits
use in St. Francis and Cross Counties ifl Arkansas to avoId
Impact on the endangered fat pocketbook mussel, Potamilus capax .
No other endangered species issues have been Identif led for
the rice and soybean uses.
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lj• TOLERANCE ASSESSMENT
Tolerances have been establIshed for the combined resiiues
of fenoxaprop-ethyl and itS metabolites on the followIng
raw agrIcultural commodIties (110 CFR 180. ):
Commodities Tolerance (ppm )
Rice grain 0.05
Soybeans 0.05
There are no international tolerances/resIdue limits for
fenoxaprop-ethyl.
There are suffic.ient resIdue dhernistry data avaIlable to
support these tolerances, including plant and animal metabolIsm,
storage stability (for both the parent compound and its
metabolites), field resIdue studies, and analytical methods.
Cattle and poultry feeding studies were not submitted. However,
under the proposed condItions of use, measurable residues are
not expected to be found in the raw agricultural commodities
or fractions. These data are therefore not now necessary.
The Acceptable Daily Intake (ADI) and the Maximum PermIssible
Intake (MPI) are two ways of expressing the amount of a substance
that the Agency believes, on the basis of the results of data
from animal studies and the applIcation of “safety” or
“uncertainty” factors, may safely be Ingested by humans without
risk of adverse health effects. The ADI IS expressed in terms of
mIlligrams (mg) of the substances per kilogram (kg) of body
weight per day (mg/kg/day). The MPI, a related figure, iS
obtained by assuming a human body weight of 60 kg, and is
expressed ifl terms of mg of substance per day (mg/day).
The Agency has calculated an ADI for renoxaprop—ethyl
of 0.0025 mg/kg/day, based on a NOEL of 0.25 mg/kg/day in the
2—generation rat reproduction study and a 100—fold safety
factor. The MPI for a 60 kg person 18 0.15 mg/Jay. These
tolerances have a theoretical maximum residue contribution
(TMRC) of 0.0011 mg/day In a 1.5 kg dIet and would utilize
.073 percent of the ADI.
5. CONTACT PERSON AT EPA
RIchard F. Mountfort
U. S. Environmental Protction Agency
TS-767C
1101 M Street, S. W.
Washington, D. C. 201460
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