United States Office of Perticidei end Toxic Sufaetencw
Environmental Protection Office of PestMMe Proorems (TS-766C)
Agency Wellington. DC 20460
vvEPA Pesticide
Fact Sheet
Name of Chemical: Metoiachior
Reason for Issuance: Registration Standard
Date Issued: January, 1Q87
Fact Sheet Number: 106
1. Description of chemical
Generic name: 2-chloro-N-(2-ethyl-6-methylphenyl)
N-(2-methoxy-l-me thylethyl)acetamide
Common name: Metoiachior
Trade names: Dual, OGA-24705, Ontrack, Pennant
EPA Shaughnessy code: 108801
Chemical Abstracts Service (CAS) number: 51218-45-2
Year of initial registration: 1976
Pesticide type: Herbicide
Chemical family: Chloracetanilide
U.S. producer: Ciba-Geigy Corporation, Agricultural Division (from
active ingredient manufactured outside the U.S.)
2. Use patterns and formulations
Application sites: For preemergence control of certain broadleaf
and grassy weeds in terrestrial crop areas (corn, sorghum, cotton,
potatoes, peanuts, soybeans, green beans, kidney and other beans,
blackeye peas and other peas, stone fruits and tree nuts) and terrestrial
noncrcp areas (ornamental plants, railroad, and highway rights-of-way).
Types of formulations: 95% active ingredient (ai) technical grade
manufacturing-use product. 5%, 15%, and 25% gram la rs, 86.4%
emulsifiable concentrate, 27.5%, 31.8%, and 36.1% flowable concen-
trate with atrazine; 36.3% flowable concentrate with propazine; and
73.6% emulsifiable concentrate with metribuzin.
Types and methods of application: End-use product is applied by
ground spray equipment, aircraft, or through center pivot irrigation
systems.
Application rates: 1.25 to 4 Ib metolachlor ai per acre (A) for
terrestrial crop and noncrop areas.
Usual carrier: Water, fluid fertilizers.
3. Science findings
Summary science statement:
-* Metoiachior is not considered to be teratogenic or cause
reproductive effects. It is not oncogenic in mice, but is considered
an oncogen in rats, and is tentatively classified as showing limited
evidence of carcinogenicity in animals. Metoiachior is not mutagenic
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in available studies, bit mutagenicity and netaboli&n testing requir rents
not in effect at the tine of issuance of the orginal MetolachlOr Registration
Standard in 1980 imist be net. Metolachior has been found in several surface
water surveys, sane tapwater samples, and in ground water in two States.
Monitoring studies are required to determine the extent of contamination on
a national scale. Metolachior is slightly to noderately toxic to nontarget
organi . Available data are insufficient to assess the enviroriTental
fate of rretolachlor.
Chanical characteristics:
Physical state: Liquid
Color: White to tan
Molecular weight: 238.8
Boiling point: 100 °C at 0.001 rrrnHg
Solubility: 530 ppm in water at 20 °C, miscible with xylene
toluene, dinethyl formamide, nethyl cellusolve, butyl
cellusolve, ethylene dichloride, and cyclohexanone.
Insoluble in ethylene glycol and propylene glycol.
Vapor pressure: About i0 rrui g at 20 °C
Toxicological characteristics:
Acute effects:
Acute oral toxicity (rat): 2780 mg/kg
(Toxicity Category III — noderately toxic)
Acute dermal toxicity (rabbit): > 10,000 mg/kg
(Toxicity Category III — rroderate ly
toxic)
Acute inhalation toxicity: ) 1.752 mg/L with 4—hour exposure
(Toxicity Category IV - non toxic)
Primary eye irritation: Non—irritating
Primary dermnal irritation: Non—irritating
Dermal sensitization: Sensitizer in guinea pig
Subthronic oral toxicity (dog): NOEL = 100 ppm (2.5 mg/kg)
Decreased gain in body weight in
males and females. Failure of
the serum alkaline phosphatase to
decrease with increased age, and
possible effects on blood clotting
syst ns at 300 and 1000 ppm.
Chronic effects:
3—generation reproduction (rat): NOEL = 300 ppm (15 mg/kg)
Reduced pup weights and reduced
parental food consumption at
1000 ppm (50 mg/kg)
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Teratogenicity: Rabbits — Not fetotoxlc or teratogenic
Maternal toxicity at high dose
(360 n J1 g/day)
Rats - Not fetotox c or teratogenic. Decrease
in food consumption at high dose (360
mgJkgJday) in first third of study.
Chronic feedigJoncogen city: Mice — Not oncogenic in two
studies up to and including
3000 ppm (429 ng/kg)
Rat - Systemic NOEL of 30 ppm
(1.5 mg/kg). Systemic tEL
of 300 ppm (testicular
atrophy). In one study a
stat1st cally sign f cant
increase in primary liver
neoplasms in females of’
high dose group (3000 ppm).
In repeat study a statistically
significant increased
incidence of neop1ast c
liver nodules and proliferative
hepatic lesions in females
of the high dose group
(3000 ppm)
Mutagenicity: Negative in an Ames Test, and a mouse dominant
lethal test.
Major routes of exposure: Dermal, ocular, arid inhalation from
mixing concentrates and applying spray
mixtures.
Phys olog cal and biochemIcal behavior characteristIcs:
Absorption: Generally applIed prior to plant emergence. Absorbed
through shoots Just above seed and possibly roots.
Mechanism of pestlcldal action: Member of group of’ chloracetarnlde
herbicides whIch are general
growth Irth bitors, especIally
of root elongation. Metolachior
may disrupt the integrity of
plant cell membranes and inhibit
lipId synthesis.
Environmental characteristIcs: AvaIlable data are insufficIent to
assess the envIronmental fate of’
metolachlor. There are indications
that metolachlor Is essentIally stable
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in loamy sand soil over 614 days.
Absorption constants in sandy clay loam,
loam, and two sand soils indicate
mobility in these SOilS. Aged
metolachior 114 C residue was mobile in
columns of loamy sand soil. Metolachior
114 C residues were mobile in sandy barns,
sand, and silt loam soil. Metolachior
l 14 C residues were detected in plants
grown in metolachlor—treated soil.
Metolachior has been found in several
surfacewater surveys. Trans ient
peaks of 1.2 to 14.1 1 ppb are reported
in riverwater possIbly as a result of
runoff during spring and summer. Detectable
levels of metolachior were found in some
tapwater samples. It has been found In
ground water in two States.
EcologIcal characteristIcs:
Avian oral toxicity: Mallard duck > 2510 mg/kg
Avian dietary toxicity: Mallard duck > 10,000 ppm
BobwhIte quaIl > 10,000 ppm
Avian reproduction: Mallard duck - showed no impaIrment at any
test level — 1,000 or 10,000 ppm
Bobwhi.te quail - NOEL = 10 ppm, impaIr nent at
300 ppm but no effect at 1000 ppm
Freshwater fiSh toxIcIty: Bluegill sunfish — 10.0 ppm
Rainbow trout — 3.9 ppm
Aquatic invertebrates: Daphnla ma a — 25.1 ppm
Fish life cycle: Fathead minnow - Maximum acceptable toxlcant
concentratIon > 0.78 < 1.6 ppm
Available data suggest that the hazard to nontarget organisms on an
acute basIs Is sli.ght to moderate.
Tolerance assessment:
Tolerances have been establIshed for resIdues of metolachbor and
its metabolltes in raw agricultural corrmoditles, milk, eggs,
meat, fat, and meat byproducts [ 140 CFR 180.368(a)] as follows:
Comodities Parts Per Million
Almond hulls 0.3
Cattle, fat 0.02
Cattle, kIdney 0.2
Cattle, lIver 0.05
Cattle, meat 0.02
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Caiinodities Parts Per Million
Cattle, meat byproducts
(mbyp) (except kidney
and liver) 0.02
Corn, fresh (inc. sweet,
kernel plus cob with
husk removed) 0.1
Corn, forage and fodder 8.0
Corn, grain 0.1
Cottonseed 0.1
Eggs 0.02
Goats, fat 0.02
Goats, kidney 0.2
Goats, liver 0.05
Goats, meat 0.02
Goats, mbyp (except
kidney and 1 ver) 0.02
Hogs, fat 0.02
Hogs, kidney 0.2
Hogs, liver 0.05
Hogs, meat 0.02
Hogs, mbyp (except
kidney and liver) 0.02
Horses, fat 0.02
Horses, kidney 0.2
Horses, lIver 0.05
Horses, meat 0.02
Horses, mbyp (except
kIdney and liver) 0.02
Legume vegetables group
foliage (except soybean
forage and soybean hay) 15.0
Milk 0.02
Peanuts 0.5
Peanut, forage and hay 30.0
Peanut, hulls 6.0
Peppers, chili 0.5
Potatoes 0.2
Poultry, fat 0.02
Poultry, lIver 0.05
Poultry, meat 0.02
Poultry, mbyp (except
liver) 0.02
Safflower seed 0.1
Seed and pod vegetables (except
soybeans) 0.3
ieep, fat 0.02
Sheep, kIdney 0.2
Sheep, liver 0.05
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Carinodities
Sheep, meat
Sheep, mbyp (except
kidney and liver)
Sorghum, forage and fodder
Sorghum, grain
Soybeans
Soybeans, forage and hay
Stone fruits group
Tree nuts group
Parts Per M 11ion
0.02
0.02
2.0
0.3
0.2
8.0
0.1
0.1
Tolerances have been established [ 140 CFR 180.368(b)] for indirect
or inadvertent residues of metolachior as a result of application of
metolachior to the growing crops listed in 180.368(a) as follows:
Comod t ies
Parts Per MilliOfl
Barley, fodder
Barley, forage
Barley, grain
&ickwheat, fodder
Buckwheat, forage
&ickwheat, grain
Millet, fodder
Millet, forage
Millet, grain
Milo, fodder
Milo, forage
Milo, grain
Oats, fodder
Oats, forage
Oats, grain
Rice, fodder
Rice, forage
Rice, grain
Rye, fodder
Rye, forage
Rye, grain
Wheat, fodder
Wheat, forage
Wheat, grain
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
0.5
0.5
0.1
Canadian tolerances of 0.1
residues of metolachior in or on
soybeans. No MexIcan tolerances
Maximum ResIdue Limits have been
metolachior.
ppii have been establIshed for
beans, corn, peas, potatoes, and
or Codex Alirnentarius Canrnission
established for resIdues of
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Results of tolerance assessment:
Using the !sI3EL of 30 ppm (1.5 rng/kgJday) from the rat chronic
feeding study and a safety factor of 100, the acceptable daily intake
(ADI) is 0.015 rr g/kg/day, and the maximum permissible intake (MPI) iS
0.9 mg/day for a 60 kg person. The established tolerances result in a
total theoretical maximum residue concentration (I!’IRC) of 0.0755 mg/day
(1.5 kg diet) WhiCh corresponds to 8.38 percent of the MPI for a 60 kg
person.
14• Sumary of regulatory positions and rationales
UnIque label precautionary statements:
Manufacturing-Use Products
&ivlronmental Hazards
Do not discharge effluent containing this product into
lakes, streams, ponds, estuarIes, oceans, or public
water unless this product Is specifically identifIed
and addressed in an NPDES’ per’mlt. Do not discharge effluent
systems without previously notifyIng the sewage treatment plant
authority. For guidance, contact your State Water Board or
Regional Office of the EPA.
End-Use Products
a. EnvIronmental hazards for emulsIfIable concentrates and
flowable concentrates
Lb not apply directly to water or wetlands (swamps, bogs,
marshes, and potholes). Do not contaminate water by cleaning
of equIpment or disposal of wastes.
b. Environmental hazards for granules
Cover or incorporate granules that are spIlled during loading
or are visible on soIl surface in turn areas. Do not
contaminate water by cleaning of equipment or dIsposal of wastes.
c. Ground water and surface water advisory
to1achlor has been Identified in limited sampling of ground
water and there is the possIbility that it may leach through
soils to ground water, especIally where soils are coarse and
ground water 18 near the suface. Following application and
during rainfall events that cause runoff, metolachior may
* NatIonal POllUtiOfl Discharge Elminatlon System
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reach surface water bodies including streams, rivers and
reservoirs.
Care must be taken when using this product to prevent back
Siphoning into wells, spills or improper disposal of excess
pesticide, spray mixtures or rinsates.
Check valves or antisiphoning devices imist be used on all
mixing and/or irrigation equipment.
d. Crop rotation statement
Crops other than beans (succulent and dry), fresh corn, grain
corn, cotton, peanuts, peas (succulent and dry), chill
peppers, potatoes, safflower, sorghum, soybeans, stone
fruits, tree nuts, and barley, buckwheat, millet, milo,
oats, rIce, rye, and wheat may not be planted in metolachlor-
treated soIl until 12 months after application
e. Endangered species statements for products regIstered for
crop uses
It is a violation of Federal laws to use any pesticide in a
mariner that results in the death of an endangered species or
adverse modIfIcatIon of their habitat.
The use of thIs product may pose a hazard to certain Federally
designated endangered specIes known to occur in specifIc areas
wIthin the CALIFORNIA counties of Merced, Sacramento arid Solario.
Before using this product in these counties you must obtain the
EPA Endangered Species Crop Bulletin. The bulletin Is avaIlable
I rcxn eIther your County ExtensIon Agent, the Endangered SpecIes
Specialist in your State Wildlife Agency Headquarters, or the
RegIonal Office of either the U.S. FIsh and WIldlife Service
(Portland, Oregon) or the U.S. Envirormiental Protection Agency
(San Francisco, California). THIS BULLETIN MUST BE REVIEMED
PRIOR ‘10 PESTICIDE USE. THE USE OF THIS H ODU IS PROHIBITED
IN THESE COUN LES UNLESS SPECIFIED OTHE1 4ISE IN THE BULLETIN.
5. Suninary of data gaps (data requIred and due date)
Toxicology
Mutageniclty studies October 1987
General matabollam October 1988
Effects on coagulation April 1987 **
** L te protocols are due. After acceptance, the Agency will provIde
tlmeframe for SUb i8SiOfl of the reports.
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EnvIronmental fate
Hydrolysis July 1987
Photodegradatlon studies July 1987
Metabolism studies January 1989
Mobility studies January 1989
Accumulation studies January 1990
Ground and surface water monitoring January 1987 **
Product chemistry/residue chemistry
Product chemistry January 1988
Plant metabolism April 1988
Storage stability October 1988
Selected residue studIes April 1989
6. Contact person at EPA
Richard F. Mountfort
U.S. Environmental Protection Agency
TS—767C
Ziol M Street 34.
Washington, DC 201460
(703) 557—1830
DISCLAIMER: The infor ation presented in this Pesticide Fact Sheet Is
for informatIon purposes only and may not be used to fulfill data
requirements for pestIcide registration and reregistratIon.
** L te protocols are due. After acceptance, the Agency wIll provIde
time frame for suth ission of the reports.
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