United States                     Office of Prevention, Pesticides
                     Environmental Protection             and Toxic Substances
                     Agency                         (7501C)

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                                  47.0% water dispersible granule
                                          end-use
                                  46.9% water dispersible granule
                                          end-use

       Types and Methods of Application: Ground application using standard commercial sprayers

       Application Rates: Application rates for soybeans range from 0.25 to 0.375 pounds active
ingredient per acre in preemergency, preplant incorporated, no-till and minimum till applications.

       Carrier: Water, crop oil concentrate, non-ionic surfactant

3.      Science Findings

Summary Science Statements

Based upon a battery of acute toxicity studies, Authority Herbicide (technical product) is classified
as Toxicity Category IE.  Sulfentrazone is not carcinogenic. However, under the conditions of the
studies reviewed, sulfentrazone caused developmental and reproductive toxicity. The results of these
studies elicited a high level of concern, since the  developmental toxicity studies demonstrated
embryo/fetal toxicity at treatment levels that were not maternally toxic, and significant toxic effects
were observed primarily in the second generation animals  of the reproduction study. Because these
animals had been exposed to sulfentrazone m utero. the possibility that the observed reproductive
toxicity resulted from  a developmental and/or genotoxic mechanism was suggested.

Chemical Characteristics - Technical Grade

Physical State - Solid

Color - Tan

Odor - Faint sulfur-like

Melting Point - 120-122C

Density - 0.53 g/ml at 20C

Solubility-7.8 X102(pH 7)

Vapor Pressure - 1  X 10'9 mmHg at 25 C

Dissociation Constant - 6.56

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Octanol/Water Partition Coefficient - Kow = 9.8 at pH 7

pH - 4.78

Toxicology Characteristics

Acute Toxicity - Sulfentrazone Technical

Acute Oral Toxicity in Rats - LD50 > 2855 mg/kg in males and females; Toxicity Category in

Acute Dermal Toxicity in Rats - LD50 > 2000 mg/kg in males and females; Toxicity Category in

Acute Inhalation Toxicity in Rats - LC50 > 4.13 mg/1 in males and females; Toxicity Category HI

Primary Eye Irritation in Rabbits - Corneal opacity, iritis, diffuse irritation within 24 hr., clearing by
day 4; Toxicity Category HI

Primary Dermal Irritation in Rabbits  - No erythema or edema  after 4-hour exposure; Toxicity
Category IV

Primary Dermal Sensitization in Guinea-Pigs - Did not exhibit any sensitization potential.

Acute Toxicity - End-Use Products

The end-use products containing sulfentrazone, Authority 4 F Herbicide, Authority 75 DF Herbicide,
Authority BL Herbicide, and Authority Broadleaf Herbicide, resulted in acute toxicity classification
of HI or IV in all areas of acute toxicity testing.   The end-use products carry the signal word
"CAUTION" to reflect toxicity category HI.

Subchronic Toxicity

A 90-day feeding study in rats resulted in a lowest-observed-effect level (LOEL) of 65.8
mg/kg/day in males and 78.1  mg/kg/day in females, and a no-observed-effect level (NOEL) of
19.9 mg/kg/day in males and 23.1 mg/kg/day in females.

A 90-day feeding study in mice resulted in a LOEL of 108.4 mg/kg/day for males and 143.6
mg/kg/day in females, and a NOEL of 60.0 mg/kg/day for males and 79.8  mg/kg/day for females.

A 90-day feeding study in dogs resulted in a NOEL of 28 mg/kg/day and a LOEL of 57
mg/kg/day for males and 73 mg/kg/day for females.

Chronic Toxicitv

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A 1-year feeding oral study was performed on dogs.  The induction of normochromic
microcytosis in animals fed diets containing 1800 ppm test material, although compensated by
increased red cell production, reflects an adverse treatment-related effect.  The microcytosis may
have arisen from the inhibition of heme synthesis as indicated by the presence of brown to
yellow/brown pigmentation in hepatocytes and reticuloendothelial cells of the liver. The
microcytosis induced by sulfentrazone justifies an oral LOEL of 61.2 mg/kg/day for males and
61.9 mg/kg/day for females. The NOEL is 24.9  mg/kg/day for males and 29.6 mg/kg/day for
females.

A 18-month feeding/carcinogenicity study in mice resulted a LOEL of 160.5 mg/kg/day in males
and 198.0 mg/kg/day in females, based upon treatment-related decreases in hemoglobin and
hematocrit. The NOEL is 93.9 mg/kg/day in males and 116.9 mg/kg/day in females.

A 2-year feeding/carcinogenicity study in rats resulted in a LOEL of 82.8 mg/kg/day in males and
67.0 mg/kg/day in females, and a NOEL of 40.0 mg/kg/day in males and 36.4 mg/kg/day in
females.  There was no evidence of carcinogenicity in this study.

Reproductive/Developmental Toxicity

A developmental toxicity study in rats resulted in a maternal (systemic) LOEL of 50.0 mg/kg/day
based upon increased relative spleen weight and splenic extramedullary hematopoiesis. The
maternal (systemic) NOEL is 25.00 mg/kg/day.  The developmental (fetal) LOEL is 25.0
mg/kg/day based upon 1) decreased mean fetal weight and 2) retardation in skeletal development
as evidenced by an increased number of litters with any variation and by decreased numbers of
caudal vertebral and metacarpal ossification sites. The developmental (fetal) NOEL is 10.0
mg/kg/day.

Evidence of treatment-related developmental toxicity consisted of decreased fetal viability,
decreased fetal body weight, and increased incidence of fetal alterations, comprised, for the most
part, of skeletal malformations and variations. A supplementary prenatal oral developmental
toxicity  study in rats confirmed the maternal and fetal findings of the previously conducted study
and did not alter the study conclusions.

In a dietary two-generation reproduction study in rats resulted in the systemic and
reproductive/developmental NOEL of 14 mg/kg/day for males and 16 mg/kg/day for females.
Mutagenicity

A reverse gene mutation assay in Salmonella typhimurium yielded negative results, both with
and without metabolic activation.

A mouse lymphoma forward gene mutation assay yielded negative results with equivocal results

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without activation.

A mouse micronucleus assay test was negative following intraperitoneal injection of 340 mg/kg.

Metabolism

A metabolism study in rats resulted in the administered dose and nearly all radioactivity excreted
in the urine, indicating nearly complete absorption. Most of the test article was eliminated by
urine and feces within 72 hours, and appeared to be independent of dose and sex.

Environmental Characteristics

Acceptable information from environmental fate studies with respect to the persistence and
mobility of sulfentrazone under laboratory and field conditions has been reviewed. Based on the
current environmental fate data base, sulfentrazone has the following characteristics: 1)
moderately soluble, 2) not susceptible to hydrolysis, 3) extremely susceptible to direct photolysis
in water, 4) very stable to photolysis on soil, 5) aerobic half-life of 1.5 years, 6) anaerobic half-
life of 9 years, 7) very high mobility in soil (average Koc = 43, Kd < 1), and 8) low volatility from
soils and water.  With these properties, it appears that sulfentrazone is highly mobile and
persistent, and has a strong potential to leach into groundwater and move offsite to surface water.

The primary routes of dissipation are through direct aqueous photolysis and leaching. Direct
photolysis would only be an  effective dissipation pathway in clear shallow waters because
sulfentrazone is stable to hydrolysis and biodegradation.  Low soil/water partitioning (average
Koc = 43, Kd < 1) indicates that most sulfentrazone runoff is through dissolution in runoff water,
as opposed to adsorption to eroding soil. It also indicates that most sulfentrazone will be
partitioned in the water column instead of in the suspended and bottom sediments.

Mechanism of Pesticidal Action

Sulfentrazone control weeds by process of protoporphyrinogen oxidase inhibition (membrane
disruption), a mode-of-action commonly referred to as PPO inhibition. Sulfentrazone is
primarily taken up by the roots of treated plants. Plants emerging from treated soil turn necrotic
and die after exposure to light. Foliar contact causes rapid desiccation and necrosis of exposed
plant tissue. Shoot-root soil  placement studies indicate that sulfentrazone is primarily absorbed
by the roots of the plant following soil applications.


Potential to Contaminate Groundwater

A groundwater exposure estimate for sulfentrazone was conducted based on findings from a
prospective groundwater monitoring  study in North Carolina.  Although the study was
incomplete, enough data were collected to  confirm that sulfentrazone leaches substantially to
groundwater in areas with sandy soils.

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Ecological Characteristics

Terrestrial

Sulfentrazone is practically non-toxic to birds on an acute oral and with an LD50 greater 2250
mg/kg.  Sulfentrazone  is practically non-toxic to birds on an avian dietary basis with an LD50
greater 5620 ppm. Mammalian results indicate that Sulfentrazone is slightly toxic to small
mammals on an acute oral basis.

Aquatic

Sulfentrazone is practically non-toxic to the rainbow trout (LC50) greater 120 ppm) and slightly
toxic to the bluegill sunfish (93.8 ppm).  The results indicate that Sulfentrazone is slightly toxic
to fish on an acute basis.  The chronic  results indicate that Sulfentrazone significantly affects
young fish survival  and growth at aquatic concentrations as low as 5.93 ppm. Sulfentrazone is
slightly toxic to aquatic invertebrates on an acute basis.

The results from data from chronic freshwater invertebrates indicate that survival of young
daphnids is adversely affected at Sulfentrazone concentrations as low as 0.51 ppm.  The results
from acute estuarine and marine animals study are incomplete but indicate that Sulfentrazone is
highly toxic to estuarine/marine organisms.

Plants

Being a pre-plant and pre-emergent herbicide, Sulfentrazone is expected to prevent the successful
emergence of non-target terrestrial  and semi-aquatic plants through soil that has been exposed.
The proposed use is not expected to pose an unacceptable risk to non-target terrestrial or aquatic
animals.
For nontarget terrestrial plant Tier II seedling emergence, the results indicate that lettuce is the
most sensitive dicot and oat is the most sensitive monocot. For Tier n vegetative vigor,
cucumber is the most sensitive dicot and onion is the most sensitive monocot.

For aquatic plant testing the results indicate that duckweed is the most sensitive aquatic plant
species.

4.     Summary of Regulatory Position and Rationale

Available data provide adequate information to support the conditional registration of Authority
herbicide as a technical product, Authority 4 F herbicide, Authority 75 DF herbicide, Authority
Broadleaf herbicide, and Authority BL herbicide for use on soybean seed, in cereal grains
(excluding sweet corn), forage, straw,  hay, grain, stover, bran and hulls.

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The registrant will add statements to the end use labels to mitigate the risk to groundwater and
will conduct further prospective groundwater studies to further address the Agency's concerns.

Use, Formulation, Manufacturing Process or Geographic Restrictions:

       Environmental Hazards

       This pesticide is toxic to marine/estaurine invertebrates. Do not apply directly to water,
       to areas where surface water is present or to intertidal areas below the mean high water
       mark. Drift and runoff may be hazardous to terrestrial and aquatic plants in neighboring
       areas. Do not contaminate water when disposing of equipment washwaters or rinsate.

       Groundwater Advisory and Labeling-Off of Soil Type: This chemical is known to
       leach through soil into ground water under certain conditions as a result of label use.
       Use of this chemical in areas where soils are permeable, particularly where the water table
       is shallow, may result in ground-water contamination.

       Do not use on coarse soils classified as sand which have less than 1% organic matter."

       Surface Water Advisory:  Sulfentrazone can contaminate surface water through spray
       drift. Under some conditions, sulfentrazone may also have a high potential for runoff into
       surface water (primarily via dissolution in runoff water), for several to many months post-
       application.  These include poorly draining or wet soils with readily visible slopes toward
       adjacent surface waters, frequently flooded areas, areas overlying extremely shallow
       ground water, areas with in-field canals or ditches that drain to surface water,  areas not
       separated from adjacent surface waters with vegetated filter strips, and areas over-lying
       tile drainage systems that drain to surface waters."

       Use Directions - General Precautions

       Do not use on crops other than soybeans.

       Use only ground application equipment. Do not apply by air.

       Do not apply this product through any type of irrigation system.

       Do not flood irrigation to apply or incorporate this product.

       Do not apply when wind speed exceeds 10 mph nor with a spray pressure exceeding 40
       psi.

       Product must be used in a manner which will prevent back siphoning in wells, spills or

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       improper disposal of excess pesticide, spray mixtures or rinsates.

       Proper handling instructions: This product may not be mixed or loaded within 50 feet
       of any wells (including abandoned wells and drainage wells), sink holes, perennial or
       intermittent streams and rivers, and natural or impounded lakes and reservoirs.  This
       setback does not apply to properly capped or plugged abandoned wells and does not apply
       to impervious pad or properly diked mixing/loading areas."

       Operations that involve mixing, loading, rinsing, or washing of this product into or from
       pesticide handling or application equipment or containers within 50 feet of any well are
       prohibited unless conducted on an impervious pad constructed to withstand the weight of
       the heaviest load that may be positioned on or moved across the pad.  Such a pad shall be
       designed and maintained to contain any product spills or equipment leaks, container or
       equipment rinse or washwater, and rainwater that may fall on the pad.  Surface water
       shall not be allowed to either flow over or from the pad, which means the pad must be
       self contained. The pad shall be sloped to facilitate material removal.  An unroofed pad
       shall be  of sufficient capacity to contain at a minimum 110% of the capacity of the largest
       pesticide container or application  equipment on the pad. A pad that is covered by a roof
       of sufficient size to completely exclude precipitation from contact with the pad shall have
       a minimum containment capacity  of 100% of the capacity of the largest pesticide
       container or application equipment on the pad. Containment capacities as described above
       shall be  maintained at all times. The above  specific minimum  containment capacities do
       not apply to vehicles when delivering pesticide shipments to the mixing/loading site.
       States may have in effect additional requirements regarding wellhead setbacks and
       operational containment."

       Use Directions - Soybeans - Preemergence - Apply only one preemergence application,
       not to exceed 0.375 Ib ai/acre per  year, up to 30 days before crop emergence.  Can also be
       applied during or after planting, but before the crop emerges.

       Use Directions - Soybeans - Preplant Incorporated - Apply only one preplant incorporated
       application, not to exceed  0.375 Ib ai/acre per year, up to 30 days prior to planting
       soybeans.

5.      Summary of Data Gaps

Toxicology Data:

       1.    21-day dermal study in rabbits

       2.    In vivo cytogenetics dominant lethal assay in rats

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Residue Chemistry Data:

       1.     Wheat processing study

       2.     Additi onal ri ce fi el d tri al s

       3.     Residue data for sorghum aspirated grain fractions

Ecological Effect Data:

       1.     Acute oyster toxicity study


6.      Contact Person at EPA

             Joanne I. Miller
             Product Manager 23
             Fungicide-Herbicide Branch
             Registration Division (7505C)
             Office of Pesticide Programs
             Environmental Protection Agency
             401  M Street,  SW
             Washington, DC 20460

       Office Location and Telephone Number

             Room 237, Crystal Mall Building #2
             1921 Jefferson Davis Highway
             Arlington, VA 22202
             (703) 305-6224
DISCLAIMER: The information presented in this Pesticide Fact Sheet is for informational
purposes only and may not be used to fulfill data requirements for pesticide registration and
reregi strati on.

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