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fluridone (Sonar, Brake, Pride) Herbicide Profile 3/86

                          CHEMICAL FACT SHEET FOR



Description of Chemical

    - Generic Name:  1-methyl-3-phenyl-5-3-(trifluoromethyl)phenyl|-

    - Common Name:  fluridone

    - Trade Name:  Sonar

    - EPA Shaughnessy Code:  112900

    - Chemical Abstracts Service (CAS) Number:  59756-60-4

    - Year of Initial Registration:  1986

    - Pesticide Type:  Aquatic herbicide

    - Status: General use

    - U.S. and Foreign Producers:

                          Elanco Products Co.
                          Div. of Eli Lilly and Co.
                          740 South Alabama St.
                          Indianapolis, IN 46285

 Summary of Regulatory Position and Rationale (Source: NPIRS):

    - Risk/benefit review:  None of the risk criteria set forth in Title
      40 Code of Federal Regulations Section 162.11 have been exceeded
      for fluridone.

    - Fluridone has been proposed only for direct application to aquatic
      sites.  No groundwater contamination issue is associated with this

Use Patterns and Formulations (Source: NPIRS):

    - Application sites:  Freshwater ponds, lakes, reservoirs, drainage
      canals, irrigation canals, and rivers.

    - Types of formulations:  Aqueous suspension, pellet

    - Types and methods of application:  Surface spray, weighted hose
      dragged near bottom; broadcast (pellet)

    - Application rates:  0.5 lb. a.i./surface acre - 4.0 lb. a.i./
      surface acre

    - Usual carrier:  water


           Fluridone controls most submerged and emerged aquatic plants.
      Some of the weeds controlled by fluridone include fanwort (Cabomba
      caroliniana), coontail (Ceratophyllum demersum), elodea (Elodea
      canadensis), parrot feather (Myriophyllum brasiliense), watermilfoil
      (Myriophyllum spp.) naiad (Najas quadalupensis), pickerelweed
      (Pontederia lanceolata), pondweed (Potamogeton spp.), arrowhead
      (Sagittaria spp), bladderwort (Utricularia spp.), Vallisneria
      (Vallisneria spp.), hydrilla (Hydrilla verticillata) and certain
      shoreline grasses such as maidencane (Panicum hemitomon), paragrass
      (Panicum purpurascens), torpedograss (Panicum repens), and reed
      canarygrass (Phalarsis arundinacea).  Fluridone has little effect on
      algae and provides only partial control of the cattails (Typha spp.).
      In addition, most floating aquatic weeds are only partially affected by
      fluridone applications (58).

      Important Weeds Controlled:  Aquatic weeds, barnyardgrass, Bermudagrass,
      blackgrass, cocklebur, crabgrass, foxtails, jimsonweed, Johnsongrass,
      lambsquarters, morningglory, nightshade, nutsedge, pigweed, purslane,
      ragweed, velvetleaf and many others (8b).

           As little as 0.1 inch of rainfall will activate the material.  A
      long residual activity, so further investigation is needed to determine
      what crops can be planted the following season after treatment.  Weeds
      may germinate and emerge from the soil before they get a chlorotic
      condition and then die.  A very broad spectrum herbicide.  Effective at
      extremely low rates.  In aquatics, little or no weed control is noted
      for 2-4 weeks (8b).


    - Chemical Characteristics

      Fluridone is a white (to off-white) crystalline solid with no odor.
      The melting point is 154-155 C.  The flash point for the aqueous
      suspension formulation is greater than 200 degrees.  Fluridone is
      not corrosive to application equipment (NPIRS).

      Molecular Formula:  C19 H14 F3 NO (62)

      Molecular Weight:   329.3 (62)

      Physical State:     Off-white crystalline solid (pure compound) (62)

      Melting Point:      151-154 C (pure compound) (62)

      Vapor Pressure:     13 uPa at 25 C (pure compound) (62)

      Solubility:         0.0012 g/100 ml water (pure compound) (58)


      Osha Standard:  NA

      NIOSH Recommended Limit:  NA

      ACGIH Recommended Limit:  NA

A.  Toxicology Characteristics (Sources other than NPIRS):

      1.  Acute toxicity:

           Fluridone was administered to rats and mice as a single dose given
      either orally or subcutaneously.  Dogs and cats received a single oral
      dose administered in capsules.  The acute toxicity of an aqueous
      suspension formulation containing 45 percent fluridone was evaluated by
      administering a single application of the material to the skin or eyes
      of rabbits.  Inhalation was evaluated in rats exposed for 1 hr to an
      atmosphere containing the compound or formulation.  The toxic effects
      of these treatments are summarized below (58).

               DERMAL:  LD50 = >2,000 g/kg (rat, technical); >500 mg/kg
                        (rabbit, technical; no irritation); >2 ml/kg
                        (rabbit, 2 AS; slight irritant) (58).

                        LD50 = >2,000 mg/kg (mouse, technical) (58).

               ORAL:    LD50 = >10,000 mg/kg (rat, technical); >10,000
                          mg/kg (mouse, technical) (58).
                        LD50 = >0.5 ml/kg (rat, 4 AS); >250 mg/kg (cat,
                          technical); >500 mg/kg (dog, technical) (58).

               INHALATION:  LC0 = >2,130 mg/m3 of air (rat, technical); >9.6
                            ml/m3 of air (rat, 4AS) (58).

               EYES:    Moderate irritant (rabbit, 44 mg/eye, technical);
                        very slight irritant (rabbit, 0.1 ml/eye, 4 AS) (58).

      2.  Subacute and chronic toxicity:

           Fluridone has been evaluated for a period of three months in rats,
      mice and dogs.   An increase in liver and kidney weights as well as the
      histological identification of liver centrilobular hypertrophy occurred
      in rats fed diets containing 1,400 pm of fluridone.  Liver
      centrilobular hypertrophy was also observed in mice receiving diets
      containing 560 ppm of fluridone.  No treatment-related effects were
      noted in rats at dietary doses of 330 ppm or noted in mice at dietary
      doses of 62 ppm.  No toxic effects were observed in dogs receiving up
      to 200 mg/kg/day of fluridone (58).

B.  Toxicology Characteristics (Source: NPIRS):

      - Acute toxicology:  Technical fluridone is in Category IV for acute
        oral effects in the rat, and is moderately toxic through acute
        inhalation exposure.  Eye irritation potential has been demon-
        strated as moderate to severe (Category III and Category II).  The
        aqueous suspension and pellet formulations are in Category III for
        oral, dermal, skin, and eye irritation effects.

      - Chronic toxicology:  A complete, acceptable chronic toxicity data
        base is available, except for a rat teratology study (second
        species).  A valid rabbit teratology study indicates no terato-
        genic response up to a dose level of 300 mg/kg/day.  Fluridone is
        not considered to have produced an oncogenic response in the mouse
        or rat.  Mutagenicity assays submitted do not indicate genotoxic
        potential, gene mutation, or structural chromosomal aberration.

C.  Physiological and Biochemical Behavioral Characteristics (Source: NPIRS):

      Fluridone is a systemic herbicide; it is absorbed from water by
      plant shoots and from hydrosoil by roots.  It inhibits carotenoid
      synthesis, which enhances degradation of chlorophyll, producing
      white (chlorotic) growing points in susceptible plants.

D.  Tolerance Assessment (Source: NPIRS):

      - A tolerance is proposed for residues of the herbicide fluridone
        pyridinone) and its metabolite (1-methyl-3-(4-hydroxyphenyl)-5-
        3-(trifluoromethyl)phenyl|-4(1H)-pyridinone) in fish at 0.5 ppm.

      - Tolerances are proposed for residues of the herbicide fluridone
        in the following raw agricultural commodities:

        Commodity                               Parts per million

        Cattle, fat                                    0.05
        Cattle, kidney                                 0.1
        Cattle, liver                                  0.1
        Cattle, meat byproducts                        0.05
        Cattle, meat (except liver and kidney)         0.05
        Eggs                                           0.05
        Goats, fat                                     0.05
        Goats, kidney                                  0.1
        Goats, liver                                   0.1
        Goats, meat byproducts                         0.05
        Goats, meat (except liver and kidney)          0.05
        Hogs, fat                                      0.05
        Hogs, kidney                                   0.1
        Hogs, liver                                    0.1
        Hogs, meat byproducts                          0.05
        Hogs, meat (except liver and kidney)           0.05
        Horses, fat                                    0.05
        Horses, kidney                                 0.1
        Horses, liver                                  0.1
        Horses, meat byproducts                        0.05
        Horses, meat (except liver and kidney)         0.05
        Milk                                           0.05
        Poultry, fat                                   0.05
        Poultry, kidney                                0.1
        Poultry, liver                                 0.1
        Poultry, meat byproducts                       0.05
        Poultry, meat (except liver and kidney)        0.05
        Sheep, fat                                     0.05
        Sheep, kidney                                  0.1
        Sheep, liver                                   0.1
        Sheep, meat byproducts                         0.05
        Sheep, meat (except liver and kidney)          0.05

      - Tolerances are proposed in the following irrigated crops and crop
        groupings for residues of the herbicide fluridone resulting from
        use of irrigation water containing residues of 0.15 ppm following
        applications on or around aquatic sites.  Where tolerances are
        established at higher levels from other uses of fluridone on the
        following crops, the higher tolerance also applies to residues
        in the irrigated commodity.  The tolerances follow:

        Commodity                               Parts per million

        Avocados                                       0.1
        Citrus                                         0.1
        Cottonseed                                     0.1
        Cucurbits                                      0.1
        Forage grasses                                 0.15
        Forage legumes                                 0.15
        Fruiting vegetables                            0.1
        Grain crop                                     0.1
        Hops                                           0.1
        Leafy vegetables                               0.1
        Nuts                                           0.1
        Pome fruit                                     0.1
        Root crops - vegetables                        0.1
        Seed and pod vegetables                        0.1
        Small fruit                                    0.1
        Stone fruit                                    0.1

      - Based on the NOEL of 8 mg/kg/day in the chronic rat feeding study
        and a 100-fold safety factor, the Acceptable Daily Intake (ADI)
        has been set at 0.08 mg/kg/day, with a Maximum Permissible Intake
        (MPI) of 4.8 mg/day for a 60-kg person.  There are no previously
        established tolerances for this herbicide.

      - The Agency is designating an acceptable residue level for
        fluridone in potable water at 0.15 ppm.  This concentration
        reflects the maximum application rate for the herbicide regis-
        tration(s) issued pursuant to FIFRA.  Consumption of water is
        estimated at 2.0 liters per day for a 60-kg adult.  These
        tolerances and the acceptable residue level in potable water
        result in a Theoretical Maximum Residue Contribution of 0.4112
        mg/day in a 1.5-kg diet (including 2 liters of water), and use
        8.57% of the ADI.

      - No Mexican, Canadian, or Codex maximum residue levels have been
        established.  Residue studies are adequate to support the
        proposed tolerances.  Plant and animal metabolism is adequately
        understood, and adequate analytical methods are available to
        enforce the tolerance levels.  The residue of concern in drinking
        water is parent compound, i.e. fluridone.

E.  Summary Science Statement (Source: NPIRS)

      Supporting data base for fluridone registration and tolerance
      proposals supporting aquatic use is complete and acceptable, except
      for a second species (rat) teratogenic study.  Original study
      submitted did not produce teratogenic response at any level tested.
      The study, however, is not adequate for regulatory purposes, because
      the highest dose tested did not produce frank maternal toxicity or
      fetotoxicity.  The study is presently being repeated.

F.  Summary of Major Data Gaps (Source: NPIRS)

    An additional rat (second species) teratology study is underway.
    Schedule for submission is July 1, 1986.

G.  Contact Person at EPA:

    Richard F. Mountfort
    Product Manager 23
    Environmental Protection Agency
    401 M Street S.W.
    Washington, DC  20460


A.  Environmental Characteristics (Source: NPIRS):

      - Degradation:  Fluridone is stable to hydrolysis.  It will photo-
        degrade (half-life is 34 hours in neutral pond water).

      - Persistence:  Under anaerobic aquatic conditions, fluridone has a
        half-life of nine months.  The half-life for fluridone in water
        is estimated to be 20 days; for hydrosoil, 90 days.

1.  Behavior In or On soils (58):

      a.  Adsorption and leaching characteristics in basic soil types:
             Fluridone is strongly adsorbed to organic matter in soil.
             Regression analysis suggests that organic matter can be used to
             predict the rate of fluridone required for herbicidal activity.
             There is also good correlation between adsorption/desorption
             coefficients and the organic matter content of the soil.  Column
             leaching studies indicate that fluridone leaches slowly in the

      b.  Microbial breakdown:  Microorganisms appear to be the major factor
             responsible for the degradation of fluridone in terrestrial

      c.  Loss from photodecomposition:  In an aquatic environment fluridone
             appears to be degraded principally by photolytic processes;
             however, microorganisms and aquatic vegetation may also be
             factors in the dissipation process.

      d.  Resultant average persistence at recommended rates:  The per-
             sistence of fluridone in terrestrial soils is complex and
             not well defined.  In most cotton producing areas, residues may
             carry over to the next cropping season and may cause injury to
             crops such as corn, sorghum, soybeans, sugar beets, and tomatoes
             that follow in rotation.  There appears to be little relation-
             ship between the rainfall pattern, soil texture and land tillage
             to soil persistence of fluridone.  When used for the control of
             aquatic vegetation, fluridone exhibits a half-life in water of
             approximately 21 days.

B.  Ecological Characteristics (Source: NPIRS):

      1.  Avian studies:

        - Acute oral (bobwhite quail), >2,000 mg/kg
          (slightly toxic).  Avian dietary (bobwhite quail and mallard duck),
          >5,000 ppm.  No impairment on reproduction for above species up
          to 1,000 ppm dietary exposure.

      2.  Aquatic species studies:

        - Daphnia magna 48-hour acute is 6.3 mg/L (moderately toxic).

        - Bluegill sunfish 96-hour acute is 12 mg/L (moderately toxic).

        - Rainbow trout 96-hour acute is 11.7 mg/L (moderately toxic).

        - Sheepshead minnow 96-hour acute is 10.91 mg/L (moderately toxic).

        - Oyster embryo-larvae 48-hour acute is 16.51 mg/L (moderately

        - Maximum Acceptable Theoretical Concentration (MATC) value for
          fathead minnow (second generation fry) was calculated to be
          >0.48 <0.96 mg/L.  No treatment-related effects were observed
          at or below 0.48 mg/L.  Total length of 3-day-old fry was
          reduced at 2 mg/L fluridone.

      3.  Potential problems for endangered species:

        - Acute and MATC values indicate a potential hazard for aquatic
          organisms in shallow areas at higher treatment rates described on
          the label.  Formal consultation with Office of Endangered Species
          (OES) has been initiated.  To minimize hazard, label directions
          provide for use of lowest listed rates for shallow areas, and
          consultation with Fish and Game Agency or U.S. Fish and Wildlife
          Service if questions arise concerning aquatic resources in the area
          to be treated.

      4.  General Toxicity to Wildlife and Fish (58):

        - Fluridone was administered to one-week old mallard and bobwhite as a
          component of the diet for four days or to adult bobwhite as a single
          dose.  Bluegills and rainbow trout were exposed to the compound for
          96 hr in static toxicity tests.  Similar static tests were
          coneducted with Daphnia magna for a duration of 48 hr.  The LD50 and
          LC50 values determined by these tests are summarized as follow:

          Species                        Route                Toxicity
          _______                        _____                ________

          Mallard                        Diet (4 days)        LC50 >5,000 ppm
          (Anas platyrhynchos)

          Bobwhite                       Diet (4 days)        LC50 >5,000 ppm
          (Colinus virginianus)

          Bobwhite                       Oral (acute)         LD50 >5,000 mg/kg
          (Colinus virginianus)

          Bluegill                       Water (static)       LC50 >9<12.5 ppm
          (Lepomis machrochirus)

          Rainbow                        Water (static)       LC50 = 11.7 ppm
          (Salmo gairdnerri)

          Daphnia (Daphnia magna)        Water (static)       LC50 = 6.3 ppm


           The chemical information provided below has been condensed from
      original source documents, primarily from "Recognition and Management
      of Pesticide Poisonings", 3rd ed. by Donald P.  Morgan, which have been
      footnoted.  This information has been provided in this form for your
      convenience and general guidance only.  In specific cases, further
      consultation and reference may be required and is recommended.  This
      information is not intended as a substitute for a more exhaustive
      review of the literature nor for the judgement of a physician or other
      trained professional.

           If poisoning is suspected, do not wait for symptoms to develop.
      Contact a physician, the nearest hospital, or the nearest Poison
      Control Center.

      SYMPTOMS OF POISONING:  No cases of poisoning have been reported or
      observed (58).

           SKIN CONTACT:  Wash affected areas with soap and water (58).

           EYE CONTACT:   Flush eyes with large quantities of water (58).


           None of the formulations are flammable (58).


           Incompatibility with water of any hardness has not been
      experienced.  Fluridone has been successfully tank-mixed with many
      other herbicides.  None of the formulations have demonstrated
      corrosiveness (58).


      STORAGE AND HANDLING:  Keep out of reach of children.  Avoid freezing.
      Store above 32 F.  Harmful if swallowed, inhaled, or absorbed through
      skin.  Avoid breathing vapors or spray mist.  Avoid contact with skin,
      eyes, or clothing (56).


                      IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
                                   (800) 424-9300


       8b. Thomson, W.T.  1981.  Agricultural chemicals - book 2:
               herbicides.  Revised ed.  Thomson Publications, Fresno, CA.
               274 pp.

      56.  Farm Chemicals Handbook, 70th ed.  1984.  R. T. Meister, G. L.
               Berg, C. Sine, S. Meister, and J. Poplyk, eds.  Meister
               Publishing Co., Willoughby, OH.

      58.  Weed Science Society of America, Herbicide Handbook Committee.
               1983.  Herbicide handbook of the weed science society of
               America, 5th ed.  Weed Science Society of America, Champaign,
               IL.  515 pp.

      62.  The Pesticide Manual:  A World Compendium, 7th ed.  1983.  C.R.
               Worthing, ed.  The British Crop Protection Council, Croydon,
               England.  695 pp.

      WGS/ 7/30/86