United Stata Offict of Potidda and Toxic Sufartanett
Environmental Protection Office of Ptttldds Program (TS-766C)
Agency Wohington. DC 20460
svEPA Pesticide
Fact Sheet
Name of Chemical: BENTAZON AND SODIUM BENTAZON
Reason for Issuance: REGISTRATION STANDARD
Date Issued: September 30, 1985
Fact Sheet Number: 64
1. Description of chemical
Cannon Names: Bentazon
Sodium bentazon (= sodium salt of bentazon)
Chemical Name: 3-U-methylethyl)-lH-2,l,3-benzothiadiazin-4(3H)-one 2,2-dioxide
3-(l-methylethyl)-lH-2,l,3-benzothiadiazin-4(3H)-one 2,2-
Trade names for Federal Section 3 Registered Products:
Manufacturing-use product: "Bentazon Manufacturer's Concentrate"
(EPA Registration No. 7969-42)
End-use product (single active ingredient): "Basagran' Fostemergence
Herbicide" (EPA Registration No. 7969-45)
End-use product (combined with atrazine): "Laddock" Postemergence
Herbicide" (EPA Registration Mo. 7969-54)
NOTE: All three of the above products have sodium bentazon as the active Ingredient„
EPA* Chemical "Code: Bentazon: 275200
Sodium bentazon: 103901
Chemical Abstracts Service (CAS) Registry Number:
Bentazon: 50723-80-3
Year of Initial Registration: 1975
Pesticide Type: Heterocyclic nitrogen herbicide
Producer Marketing In U.S.: BASF Wyandotte Corporation
2. Use patterns and formulations
Application sites:
soybeans, rice, corn, sorghum, peanuts, beans (dry or succulent), peas (dry or
succulent), established pepperalnt and spearmint, established ornamental turf.
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only additional site under Section 2’ (c) (special local need) r istration
is Bohemian chili peppers.
Percent of Particular Crops Theated with the Pesticide as of i98 i:
soybeans 20%
rIce 10%
dry beans and peas 5%
peanuts 2%
corn <1%
Percent of PestIc i de Applied to PartIcular Crtç as of 198 1 4:
soybeans 96%
corn 2%
rIce 1%
dry beans and peas <1%
peanuts <1%
Types and Methods of Appilcatlon:
&yiltzri bentazon Is applIed, by ground or aIr, as a broadcast foliar spray
after the crop art! weeds have energed fr ay the soil. It Is used to control
selected broadleaf weeds and sedges only.
ApplIcatIon Rates:
Rate , from 0.75 lb active IngredIent (a.I.)/acre to 2 lb a.I./acre, vary
by crop, geographic regIon, target specIes, and sIte cort!itions.
Types of Pornulatlons:
The manufacturing-use product ls a ‘i6% sod1 n bentazon llcpid. Basagran’
Postenergence HerbicIde Is a “soluble liquid concentrate” contaIning 142% sodium
bentazon. taddoclC Postsnergence Herbicide Is a “flo eble liquId concentrate”
contaIning 18.52% sodIum bentazon and 16.96% atrazine.
Usual CarrIers:
The usual carrIer is water. An oil, concentrate is used under certain condItIons ,
3. ScIence Pthdthg
Chenical Characteristics:
cthical grade beitazon (isolated before formation of sodium bentazon) Is an
odorless, ron—volatile solid with a melting çoint of 137—139°. It’s solubillty
(g/100 g solvent, 20°C) is 0.05 In water and 150.7 in acetone. Sodium bentazon
Is considerably tiore soluble in water than bentazon, with a solubility of 230
g/100 g in water.
Mannalian Toxlcolcgy Characteristics:
Acute toxicity:
Sciiun bentazon is In ‘Ibxicity Category UI (defined In 40 CFFL 162.10), based upon
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acute oral. toxicity in the rat and acute derrnal testi€ in the rat. An acute
Inhalation study is supplen&ttary (vali i but does not meet EPA guideline
requ.irenents) and will need to be repeated.
Subchronic toxicity:
Subchrcnic data are supplenantary (90-clay rat feeding study and 13—week dog
study; bentazon) or invalid (21-day dennal study; soditzn bentazon), aiti will
requLre replacenent. Ccmpound-related effects were seen at 300 and 3000 pçm
test levels In the dog study (numerous effects at 3000 ppn; prostat tis at
300 ppn ‘es basis of lowest—effect—level of .300 ppn and no—effect level of’
100 ppn). A one year dog study is required for hazard assessment.
Chronic ¶Lbxic tty:
All chronic tox c ty data for bentazon are supplenentary or invalid, and will
require replac nent. 2 1 4—month rat and l8-rxnth mouse studies have been invalIdated
and a “for cause” laboratory audIt requested, d.e to substantIal defIcIencies.
In a supplementary mouse oncogenlc lty study, no specIfic clinical or petholog lcal
sslnptoms could be associated with bentazon exposure.
A rat 3-generatlon reproductIon study found no conpound-related effects for
bentazon up to a dIetary level of i8o ppn. However, without effects at the
highest dose, the dose selection is considered inadequate.
The available rat and rabbIt teratosenicity studIes are inadequate, but do not
suggest that bentazon Is a potent teratogen or fetotox lc agent. Terata were
observed in one rat study at a dose of 200 ng/kg/day, but the utIlity and valIdity
of these data are in question. Additional teratology studIes in the rat and
rabbIt are required.
A varIety of mutagenlcity studIes (analytical grade bentazon; or sodIum salt)
have been revIewed, but none are adequate for regulatory purposes. This Is
also the case for metabolism studIes with labeled bentazon.
Physlologlcal and Biochemical. Behavioral CharacterIstIcs:
MechanIsz of pestlcidal action:
Fbliar applIcation of sodium bentazon results In photosynthesIs inhibItIon In
susceptible specIes. Visible injury to the treated leaf surface usually occurs
in 4—8 hours, followed by plant death.
FO1Iar absorption ant translocation:
Battazon applIed post-emergence to yotrig plants may be absorbed and translocated
fran the site of applIcation. The degree of translocation depends on the plant’
species. Whether translocated or not, baitazon is rapIdly metabolized, conj ugated,
aid incorporated into natural plant conponenta.
th.bo1isn in plants and animals:
lie metaboliss of bentazon In tolerant plants l.a pertially understood. The
6—hydroxy ant the 8-hydroxy metabolites are Included with bentazon In the tolerances
at crops. Further s rk Is necessary to characterize other metabolites.
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The metaboli in animals is not understood as the acid hydrolysis procedire
was not r i on any of the methanol extracts of eggs and roultry tissues. Ib ver,
in animals there Is no bydroxylatlon of bentazon as in plants. Based on available
Information, the residues in animals consist of the metabolite AIBA and bentazon,
and tolerances for residues in animal products sk uld be expressed in terms of
these canbined residues.
Envlrormenta]. CharacterIstics
Ca1 X)sIti.ofl:
Based on available, vaildated data, bentazon appears to be stable to hydrolysIs,
but photodegrades in water with a half-life of <214 hours. It also photodegrades
soil. Under aerobIc conditions in lab and field, bentazon degrades with a
half-lIfe of <1 rixnth in soil.
BIoacci m iu1atIon:
Bentazon resIdues accunulate in the tail meat and vIscera of crayfIsh with
bloconcentratlon factors of
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Potentla]. probl ns related to erxlŕngered species:
Biological opinions (covering all r istered pesticides) have been receIved from
the U.S. Fish ard WildlIfe Service Office of Endangered SpecIes (OE ) for three
of the crops for wuleb sodlun bentazon is r istered: corn, sorgh , and soybeans.
To avoid Jeopardy to the Valley Elderberry Longbrn Beetle ( De noceruz californIcu
dirnorthus) , OES indicates that herbIcIdes should be prohIbIted from designated
areas in CalIfornia In order to protect the host plant, elderberry ( San bucus
spp.). Labeling developed by EPA to imp1 nent this prohibition Is described
below.
The above opinions also stated that “ .. . to avoid Jeopardy to Solano grass.. . the
use of any herbIcIdes toxIc to gram.tnoldes should be prohIbIted within.. .“ certain
defined geographIc areas of California, because of concerns with spray drift
and runoff from agrlculture]. areas. Solario grass ( Tuctorla (= Orcuttla)
mucrorlata ) is an endangered plant specIes found in a vernal lakebed in Solano
County, CalIfornIa. Since no grass species are claimed on exIsting labelIng
to be controlled with sodi.um bentazon and the herbicide is used on varIous
grass crops, EcologIcal Effects Branch (with informal consultation with OES) dld
not consIder there to be a threat to Solano grass fran the r Istered use of
this chenical. Subsequently, infonratlon has been located indIcating that
sod liin bentazon may affect certain germinating grass specIes with dIrect exposure
at full dosage rates, but that it does not affect grasses after germinatIon.
Solano grass germinates in r’arch and pril. The earlIest planting date for
corn, sorgh .zn, or soybeans Is for corn, which can be planted as early as AprIl 15.
Since sodIum bentazon Is applIed postanergence to the Weeds, there may be lIttle
opportunlty for an applicatIon that could affect Solano grass. Further consultatlor
with OES wIll be InItIated. Label restrIctIons, as above, and/or plant protectIon
data requlrenents (under 0 CFR § 158.150) may be imposed.
n oyster st dy and further erivlrorrnental ch nis try data are requIred, in
part, to evaluate whether there Is any hazard to endangered mussel specIes
from sodIi .z beritazcn use.
The Agency Is not aware of any other data which would suggest that the rIsk
crIterIa of § 162.11 have been met or exceeded for the uses of sodium bentazon
at the present time.
‘ IOLEPANCES
In the UnIted States, tolerances are currently establIshed in 14Q CFR §180.355
for canbined resIdues of bentazon (3—Isopropyl—1H—2 , 1, 3-benzothiad Iazin- 4 (311)-
one-2,2—dloxlde) and its .6— and 8—hydroxy metabolltes In or on agrIcultural
commodItIes as follows:
Cc rmodIty parts per mIllIon
Beans (except soybeans), dried 0.05
Beans (exc. soybeans), drIed, vine hays 3
Beans (exc. soybeans), forage 3
Beans, lirna (succulent) 0.05
Beans, succulent 0.05
Bohertan chill peppers 0.5’
Corn, fodder 3
Corn, forage 3
Corn, grain 0.05
Corn, fresh (md. sweet K+OiIHR) 0.05
Mint 1
Peanuts 0.05
Peanuts, hay 3
Peanuts, hulls 0.3
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Peanuts, forage 3
Peas (dried) 0.05
‘Peas (dried), vine hays 3
Peas, forage 3
Peas, s ccul rit 0.5
Rice 0.05
Rice, straw 3
Sorgh n, fodder 0.05
Sorghun, forage 0.20
Sorgh n, grain 0.05
Soybeans 0.05
Soybeans, forage 3
Soybeans, hay 0.3
and
b) canbined residues of bentazon (3—isopropyl-1H—2,1,3—benzothiadiazin- 1 4(3H)—
one-2,2-dloxlde) arxi its metaboilte 2-amino-1 I—1sopr’opyl benzarnlde in raw
agrIcultural ca inodItIes as follows:
Corrinod lty parts per
mIllion
Cattl , fat 0.05
Cattle, mbyp o.os
Cattle, meat 0.05
Eggs 0.05
Goats, fat 0.05
Goats, mbyp 0.05
Goats, meat 0.05
Hogs, fat 0.05
Hogs, mbyp 0.05
Hogs, meat 0.05
Milk 0.02
Poultry, fat 0.05
Poultry, mbyp 0.05
Pb1. ltry, meat 0.05
Sheep, fat 0.05
Sheep, mbyp 0.05
Sheep, meat 0.05
The mlsprinted tolerance of 0.5 ppn for Bohemian chili peppers will be
corrected to read 0.05 ppn.
Tolerance reassessm ’it cannot be corx ucted because of toxicology and
residue chemistry data gape.
International Tolerances:
There are 0.1 ppn Canadian tolerances for b tazon on soybeans, beans,
peas, corn, rice, ani peanuts. Prese tly, there are no MexIcan or
Codex Alimentarius tolerances for b itazon.
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L • Sunnarj of Re latory Position arid Rationale
The available data do not indicate that any of the risk criteria listed in
§ 162.11 (a) of Title 140 of the U.S. Code of Federal R ulatioris have been n t
or exceeded for the uses of sodIum bentazon at the present time. However,
su3stantlal data gaps exIst (see below). Under FTh’RA §3(c)(2)B), the registrant
must provIde or agree to develop thIs data to maititairi the exIsting tIP reg stratIor
or to perm!.t new registratIons of substantially s!inilar sodiun bentazori tIPs.
The Agency will canplete Its hazard evaluation, or determine what further data
are necessary to do so, upon review of the data being requIred under thIs
RegIstration Standard. The Agency will determine at that time if such data
wIll affect the regIstrations of bentazon. If such review determines that
crIteria for determinatIons of unreasonable adverse effects are met or exceeded
(as specifIed under §162.11), a rebuttable presumption shall arIse that a
a notIce of intent to cancel regIstration(s) pursuant to FTFRA §6(b)(1) (Or a
notIce of intent to hold a hearing to determine whether the regIstratIon(s)
should be cancelled) may be Issued. If, at any time, revIew of the data
indIcates that an mlnent hazard (as defined by FTh’RA § 2(1)) Is posed by
continued bentazon use, Iimiediate suspensIon procedures may be initlated as per
F ’RA §6(c)(1).
No new uses of sodium bentazon will be permItted until the data base Is adequate
to ca plete a hazard assessment. As per ConditIonal egistratIan Interim Final
Regulations (FR Vol. L 14, No. 93, May 11, 1979), no new uses or new products may
be regIstered without “data suffIcIent to allow the Agency to determine that
approval of the applIcatIon would not cause a significant increase in the rIsk
of unreasonable adverse effects on the envlrorment”. For bentazon, the entIre
subchronlc and chronlc toxlcology data base (required to evaluate hazards to
humans/dcrnestlc animals from exIstIng uses) Is invalid or otherwise inadequate,
arid tnus totally insuffIcIent to evaluate any new uses. The Agency is unable
to complete a tolerance reassessment of bentazcn because of these gaps, as well
as resIdue chemIstry data gaps.
The Agency Is uiable to fully assess potential human exposure, potentIal for
ground ater contaminatIon, or complete an ecologIcal, effects hazard assessment
of exI t1rig sodIum bentazon uses beca .ise of exposure assessrnent/envirormental
i n! t y data gaps. There are also certain product chemistry, wildlIfe/aquatIc
organ n, and riontarget insect data gaps that prevent full assessment of exIsting
use.
ClarIfIcatIon or verification of all test materials used In studies
submitted by the regIstrant Is required. The Agency reserves the rI t to
impose additional testing of’ eIther bentazon or sodium bentazon following
review of this information and/or review of new sttziies suthiltted to fulfill
data gaps identlfled in this Standard.
All manufacturing-use and end-use products containing sodIum bentazon must bear
oppropriate labeling as specified in 40 CFR §162.10. The following statements
are also required. All labeling changes must appear on all products released
for shipeent by September, 1986. All labeling changes niist appear on all products
in channels of trade by September, 1987.
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Manufacturing-use Products
“!) not dIscharge effl nt containing this product into lakes, streams,
porx s, estuaries, oceans, or public waters unless this product Is
specifically identified and addressed In a National Pollutant Discharge
El inatIon System (NPDES) pen nit. not dIscharge effluent containIng
this product to sewer systems without prevIously notIfying the sewage
treath ent plant authorIty. For guIdance, contact your State Water
Board or RegIonal OffIce of the U.S. E virorznerital Protection Agency.”
When cItIng the bentazon equivalent, the-chemIcal name for bentazon
should be wrItten as “3—(l —methylethyl)—1H—2, 1 ,3—benzothiad azjn—Lj (3H)—
one 2,2 dIoxIde”.
&x —Use Products
“ not graze treated corn fIelds for at least 12 days after the
last sodluri bentazon trea ent.”
“D3 not graze treated peanut fields for at least 50 days after the
last sodlun bentazon treat nent.”
“DD not rotate crops used for food or feed, whIch are riot regIstered
for use with sodIum bentazon, on areas prevlously treated with this
chemIcal .“
“E not use sodium bentazon on rlce fields in which the cai ercIal
cultivatIon of catflsh.or crayfIsh Is practiced.”
“to not use water containing bentazon or sodium bentazon resIdues from
rIce cultIvation to Irrigate crops used for food or feed unless sodlum
berit.azon Is regIstered for use on these crops.”
For all uses except rIce: “!) not apply directly to water or wetlands.
E not contaminate water by cleaning of equipnent or dIsposal of wastes.”
For rIce use: “Eu not contaminate water by cleanIng of equipnent or
dI posai of wastes .“
For corn, soybean, and sorghum uses:
“ NotIce : It Is a vlolatlon of federal laws to use any pestlclde in a
manner that results in the death of an endangered specIes or adverse
modIfication of their habitat.
“‘t1 use of this product may pose a hazard to certain federally
desi. ated endangered species laDwn to occur In specific areas
within the CALIFCRNIA countIes of Merced, Sacramento, and
Solano. Before using this product In these counties you must
obtain the EPA &xlangered Species &alletin specific for these
areas. The bulletin (EPA/ -85-6) Is available fran either your
County Agricultural &tenslon Agent, the iangered Species
Specialist In your State Wildlife Agexxiy Headquarters, or the
Regional Office of the U.S. Fish and Wildlife Service_(Portland,
Oregon). ThIS BULlETIN Mt. T BE REVIEWED P LICR W k rICIIE tEE.
THE LEE OF ThIS FRODUCT IS PRCHTh 1ED IN THEE COUWrIE UNL S
SP IFIED OrH lISE IN ThE BULLEPIN.”
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Wnen citing the bentazon equivalent, the cI nical name for bentazori
slxuld be written as “3— ( 1-r thylethyl ) -1—2,1, 3—benzothiadiazth- - (3H )—
one 2,2 dioxide”.
& 1Tnary of Major T ta Gaps:
There are n ierous generic data gaps in the areas of product chemistry, residue
ch nistry, envirorinental fate, arxi ecological effects.
GenerIc toxicology data gaps and tune frames for submIttal are as follows:
Acute !.nhalation toxicity—rat 9 months
90—day feeding—rodent 15 months
—non-rodent (dog) 18 months
21—day dennal—rabbi.t 12 months
ChronIc toxicIty— rodent 50 months
—r n—rodent (dog) 50 months
Oncogenlclty—rat (preferred) 50 months
—mouse (preferred) 50 months
Teratogen lc lty—rat 15 months
—rabbIt 15 months
ReproductIon—rat (2—generatIon) 39 months
Mutagenlclty—gene mutatIon (knes ‘1 st) 9 months
—structural chranoscn aJ. aberratIon 12 months
Mutagenlcity—other genotoxic effects 12 months
General metabolIsm (using bentazon a.rxi sodlu’n bentazon) 2l months
Dennal PenetratIon 12 months
Product-speclflc data on the manufacturing-use product include product
chemIstry data and two acute toxIcology studIes.
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