United States Office of PtstMdm and Toxic Sutetane«
Environmental Protection Office of Pesticide Program (TS-766C)
Agency Vtehlngton. DC 20460
v>EPA Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuance:
Date Issued: June 30f 1984
Fact Sheet Number:
1. Description of the chemical;
Generic name: 3-(3,4-Dichlorophenyl)-l-methoxy-l-methylurea
Cannon name: Linurcn
Trade name: Alfanox*, Linurex*, Londax . Lorox*
EPA Shaughnessy Code: 035506
Chemical Abstracts Service (CAS) Registry number: 330-55-2
Year of initial registration: 1966
Pesticide Type: Herbicide
Chemical family: Substituted urea
U.S. and foreign producers: E. I. duPont de Nemours and Company, Drexel
Chemical Company, Griffin Corporation, Vertac Chemical Corp., Bayer AG,
Makhteshim-Agan, Permwalt Holland B. V., Rhone-Poulenc, Staveley
Chemicals Ltd., and Universal Crop Protection Ltd.
2. Use patterns and formulations;
Application sites: Linuron is a substituted urea compound registered
for use as a herbicide to control a wide variety of annual and perennial
broadleaf and grassy weeds on both crop and noncrop sites. Linuron is
registered for use on numerous crop sites such as forage crops, field
crops, fruits, vegetable, and ornamental crops. In noncrop applications,
linuron is used on alleys, fencerows, fairways, highway right-of-way,
sodfields, streets, and vacant lots.
Types of formulations: Linuron is available as a wettable powder,
granular flowable, and liquid suspensions.
Types and methods of applications: Linuron is applied as follows:
broadcast or band upon the soil surface using ground or aerial equipment.
Application rates: 0.5 IDS. a.i./A to 3.0 Ibs. a.i./A on crop sites;
and 1.0 Ibs. a.i./A to 3.0 Ibs. a.i./A on noncrop sites.
Usual carriers: Mater, oil and clay.
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3. Science Findings :
SuTn ry science stat nerits:
Linuron has lc acute m tii alian toxicity and it’s uses are not expected
to adversely affect avian and m mialian wildlilfe. The metaboli n of
linuron in plants and animals is adequately understood.
Dietary exposures to linuron have induced dose related tu crs in the
rat testes and rr ise liver. The available toxicology data are in—
3ufficient o gully assess the iongterm reprod .ct ive and teratcçenic
otencial of linurcn.
anica1 characteristics:
Technical linuron is an odorless, white, crystalline solid. it is stable
t rds oxidation and noisture under conventional conditions and decanp,ses
at 180_190cC. The ch nical does not e ibit any unusual handling hazards.
Toxicological characteristics:
Acute toxicology studies on linuron are as follc ,s:
Oral W j in rats: 1,500 ma/kg body wa ight, Toxicity Category 111
De nal L1 j in rats: > 2,000 mJkg body waight, Toxicity Category III
Inhalation I C 50 in rats: 218 n J1/hr, Toxicity Category IV
Skin irritation in rabbits: slight irritant, Toxicity Category III
Eye irritation in rabbits: slight irritant, Toxicity Category III.
thronic toxicology studies on linuron are as foll s:
A t year chronic feeding study on rats has ah that interstitial
testicular (ISC) adenanas occured in all dosage groups (control, 50 • 0,
125.0, and 625.0 ppn) both during the t years and then at term.
A chronic feeding study was conducted on male and f nale mice at diet
levels of 0.0, 50.C, 150.0, and 1.500 pp of linuron. The study sh c
a statistically significant increase of hepatocellular adencras in the
fanale mice frcr the highest dose group (1,500 ppn). A significant
increase of hepatocellular adenanas was also served anong the males
in the l st dose group (50 ppn). The levels of methart lobin ware
increased in treated mice of both sexes; this increase was related to
the linuron ac ninistration.
A t year dog study did not danonstrate carcinogenesis but sh d
hat iderin deposition at 125 and 625 ppn.
In several mutagenicity tests, Linuron did not affect I 1A repair but
i y have inhibited imcuse testicular [ A synthesis. Linuron has rot
been sh n to be active in the nes test. Linurcn did not affect
S. typhizmiriun in vivo in the nouse peritoneal cavity.
Major routes of hLrnan exposure:
The non-dietary exposure to 1 inuron by a farmar as an applicator or
mixer/loader is very high.
The dietary exposure to linuron residues by the U.S. population is
probable because of its consui t ion of treated crops.
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Physiological and Biochønical Behavioral aracteristicS:
Absorption characteristics: Lirnzon is most readily absorbed through
the rcot syst n; less through foliage and støns.
Translocat ion: Linuron is translocated u iard pr imarily in the xyl n.
Mechani9n of pesticidal action: It is a strong inhibitor of photc ynthesis
(Hill reaction).
Enviromental characteristics:
kisorption and leaching in basic soil types: Msorption increases
as clay content and/or organic matter content of soil increases;
clays of high exchange capacity absorb more linuron than those of
lc exchange capacity.
Microbial breakdc n: microbes are the primary factor in the breakd n
of linuron in soils.
The available envirorriental fate data are insufficient to fully assess
the de radation, metaboli , mobility, dissipation and accunulation
activities of linuron. W en additional st .xhes are sutznitted, a
canpiete envirorriental asses nent can be made.
Ecological characteristics:
Aviar LC5C: >3,000 rt /kg,
Fish LC 5 O: (9E. hour), 16 pp for bluegill and rainb trout,
L.C 50 : (72 hour) >40 pp foi crawfish,
LC 50 : (48 hour) >40 pp for tadpole.
W en additional ecological effects data are sutinitted, a cat lete hazard
asses tent can be made.
Tolerance asses nents:
Since linuron and diuron have certain metabolites in ca rrcn El—(3,4—
dichlorcphenyl)—3-methylUrea (WPMU)F and 3,4—dichiorophenylurea (DCPUfl,
the Agency will consider diuron’ s residue contribution in the tolerance
reassess nt of linuron for the following ccrrcdities: corn, sorghun,
grains, wheat, asparagus, meat ( red), ana cottonseec.
If the canplete tolerance reassess nts for the above cani dities are
favorable, tolerances for residues of linuron and metabolites (which will
hydrolyze to form 3,4—dichloroaniline) will have to be proposed for
residues in milk and eggs at 0.05 ppn.
The tolerances listed below have not been revised:
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Ccz,m iities Parts per million
Asparagus 3.0
CaLLots 1.0
Cattle, fat 1.0
Cattle, meat by-products 1.0
Cattle, meat 1.0
Celery 1.0
Corn, field, fodder 1.0
Corn, field, forage 1.0
Corn, fresh, (s et) 0.25
Corn, grain (inc. pop) 0.25
Corn, pop, fodder 1.0
Corn, pop, forage 1.0
Corn, s et, fodder 1.0
Corn, s et, forage 0.25
Goats, fat 1.0
Goats, meat by—products 1.0
Goats, meat 1.0
Hogs, fat 1.0
Hogs, meat by-products 1.0
Hogs, meat 1.0
Horses, fat 1.0
Horses, meat by—products 1.0
Horses, meat 1.0
Parsnips (with or without tops)
Parsnips, tops 0.5
Potatoes 1.0
Sheep, fat 1.0
Sheep, meat by—products 1.0
Sheep, meat 1.0
Sorghun, fodder 1.0
Sorghun, forage 1.0
Sorghiin, grain(milo) 0.25
Soybeans (dry or succulent) 1.0
Soybeans, forage 1.0
Soybeans, hay 1.0
W-ieat, foraae 0.5
Wieat, grain 0.25
eat, hay 0.5
eat, straw 0.5
Problens knc in to have occurred with use:
Exposure of htrans to 1 inuron through runoff contaninat ion of surface
ter after heavy Spring precipitation has occurred in Northwestern
Ohio.
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4. surnary of regulatory position and rationale :
Use classification
Restricted use classification.
Unique label warning stat nts:
The use of this product may be hazardous to y .ir health. This product
contains linuron, which has been determined to cause tu rs in labbratory
anij als.
t not reenter treated areas for 24 hours fo11 ing application unless
protect..ve clothing is rn.”
Slkmlnary of risk/benefit revi :
The ency has determined that 1 inuron has exceeded the oncogenicity risk
criteria and requires special review. Dietary exposure to linuron
indicated clear evidence of oncogenicity for male rats using the NTP
criteria. Using these data, the ency calculated nondietary risk.
The n ,st realistic scenario is a fant r with no protection, who mixes/
loads and apçlies this herbicide. This calculation resulted in a risk
of 3.6 x 10—i to 2.2 x It is possible that the actual risk may
even be higher, because the c narcial applicator exposure was not
included. The J ency also calculated dietary risk. The n st realistic
scenario for dietary risk is the inaticn of maxuTnjn residue expected
(PEE) and percent which resulted in a risk of 1.5 x 1O- 5 .
5. &riinary of major data Q :
The fo1lc ing t icO1ogy data are required:
teratology studies, one in rat and one in another species (rabbit).
A two-generation reproduction study in rats is required; this study
be designed to incorporate concerns regarding the significance
of interstitial cell adencras. Note that in the former studies (rat
and dog), ret iculocytes and erythroid precursors ware not measured.
This is a data gap, since at the high dose level (625 ppn), he ,siderin
was thserved in rats and also at 125 and 625 ppn in the dog. (This
data may be filled by apprpriate design inclusion into the required
reproduction study above. The registrant nust consult with the P ency
on the apprcpriate protocol.)
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Mutagenicity and related data are required, which (1) satisfy
the 3 mutagenicity testir , category requira nts, (2) adequately
identify the risks, and where possible identify the mechanians
associated with positive findings in rodent chronic studies.
The Agency is requiring data, relating levels of suif— and
math r jlthin foll irç dietary exposure for certain sLbstituted
phenyl urea canpounds such as 1 inuron. This testing may be
caitined with other testing involving dietary e sure, such as
the reproduction study. Dse levels must be such that a NOEL. may
be established.
The folla ing four mutagenicity studies have been received and are
in Agency review:
1. Pkitagencity Evaluation In (Salncnella typhimuriun)R, HL.R 1006—83,
5/5,’8 3,
2. “Unscheduled I] A Synthesis/Rat Hepatocytes In Vitrou, HLR 190—83,
6/3/83,
3. “a1O/H r Assay for Gene Mutation”, HIP 540-83, 12/16/83,
4. “In ‘Jivo Bone Marr aira csa e Study in Rats”, HI O 378—83, 9/1/83.
The available toxicology data are insufficient to fully assess the
long—term reproductive, and teratogenic potential of linuror..
Long—term studies must be su nitted fran one to t years after
receipt of the guidance package. Please refer to the toxicology
data tables under S 158.135 for the specific dates for which lorç
term data must be suthUtted. Short—term studies must be sutrnittec
within six rTonths after receipt of this guidance package.
The follc ing envirorirental fate data are required:
Hydrolysis test,
Photodegradation test in water,
Photcxiegradaticn test in soil,
Photcxiegradat ion test in air,
Metabolian test in aerobic soil
Metabol ian test in anaerobic soil,
Leaching and adsosrptiorVdesorption,
Mobility (volatility) test in the lab,
Mobility (volatility) test in the field,
Dissipation study in soil,
Dissipation study in soil (long tterrn),
Acctznulat ion study in fish,
Special Testing on applicator exposure,
Reentry data requiranents.
Long-term studies must be su nitted fran one to four years after
receipt of the guidance package. Please refer to the enviroruental
fate data tables under S 158.130 for the specific dates for which
long term data twist be subuitted. Short—term studies must be
sutxnitted within six .n nths after receipt of the guidance package.
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The foflc ing ecolc ical effects data are required:
Acute avian toxicity,
Acute toxicity, freshwater fish,
Acute toxicity, freshwater invertebrates.
Acute studies rr ast be sihnitted within six i nths after receipt of
this guidance package.
The physical/ch ical requirdnents listed in the S158. 120, Product th nistry
data tables .ist be sutxnitted, particularly:
Solubility,
Vapor press e,
Cotanol/water partition coefficient.
These studies n ist be sukrnitted within six ncnths after receipt of this
guidance package.
The fol1c ing residue data are required:
Residue data for asparagus, carrots, celery, cczn , cottonseed, parsnips,
potatoes, sorghu ,, soybeans, and theat are required to reflect uses
of the 50%, dry fl able (DP) and 4 lb/gal, fl b1e concentrate (P lC)
forrmilations. Data reflecting uses of the 50% CF are required for the
foll inrç cai xiities: carrots (aerial a lications), potatoes (aerial
applications), soybeans (pre nergence), so ght.in (forage), wheat (forage
and hay), asparagus (pre i rgence), and cottonseed (t a 1ications
per season). Data pertaining to residues in dehydrated potato products
are required.
Long—term studies must be si.friitted within one year after receipt of
this guidance package.
6. Contact Person at EPA :
ert J. Taylor
Product Manager (25’
Env irorir ntal Protect ion ency (TS-767C)
401 M Street, S.W.
shington, D.C. 20460
(703) 557—1800
DISC lAIMER: This information presented in this thenical Information Pact
Sheet is for information pur es only, and may not be used to fulfill
data requir x*nts for pesticide registration and reregistration.
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