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v>EPA       Pesticide
                    Fact  Sheet
                    Name of Chemical:   Ethephon
                   Reason for Issuance:  Registration Standard
                    Date  Issued:         September 29, 1988
                    Fact Sheet Number:  176
     1.  Description of Chemical

         Generic Name:   Ethephon
         Common Name:   Ethephon
         Trade Names:   Broneflor, Cerone, Chlorethephon (New Zealand),  Ethrel,
                       Florel, Prep and Flordimex
         EPA Shaughnessy Code:  099801
         Chemical Abstracts Service (CAS) Number:  16672-87-0
         Year of Initial Registration:  1973
         Pesticide Type:  Growth Regulator
         U.S. and Foreign Producers:  AmChem/Union Carbide
                                   Rhone-Poulenc               •

     2.  Use Patterns and Formulations                                .

         Application Sites:  To enhance fruit ripening, flower initiation,.
            fruit and leaf abscission, and breaking of apical dominance  in
            apples, barley, wheat, blackberries, boysenberry, blueberry,
            cantaloupe, cherry (tart and sweet), cotton, cucumber, squash
            and pumpkin (hybrid seed production), figs, cucumber  (pickling),
            filberts, grapes, lemon, tangerine, tangelo, pepper, pimento,
            tomato, walnut, tobacco (flue cured), ornamentals, guava,
            grapes for  table and raisin production, pineapples, sugarcane,
            coffee beans, cottonseed, macadamia nuts, trees (forest and
            shelterbelt)  and cranberries.

         Mechanism of Action:  Generation of ethylene after application  (ethylene
            is a naturally-produced plant hormone).

         Types of Formulations:  Emulsifiable concentrate, soluble
            concentrates/liquids, ready-to-use liquids.

         Types and Methods of Application:  Broadcast by ground or aerial


    Application Rates:  Vary from 0.08 to 2.0 pounds of active ingredient
       per acre depending upon the use site and desired effects.

3.  Science Findings

    Chemical Characteristics;
       Empirical  Formula:
       Molecular  Weight:  144.5
       Physical State:  Waxy, solid
       Color:  White
       Melting Point:  74 to 75 °C
       Solubility:   Very soluble in water, alcohol, propylene glycol;
                    very slightly soluble in aromatic solvents.

    Toxicology Characteristics:

    Acute Effects

       Acute Oral Toxicity:  1.6 g/kg rats (Toxicity Category III)

       Acute Dermal  Toxicity:  > 5 g/kg rabbits (Toxicity Category III)

       Acute Inhalation:  Not available

       Primary Eye Irritation:  Not available, but assumed to be corrosive
                               based on the primary dermal results

       Primary Skin  Irritation:  Score 6.75 (Corrosive) rabbits
                                (Toxicity Category I)

       Delayed Neurotoxicity Hen:  No signs of neurotoxicity

    Sub-Chronic  Effects

       No adequate data are available on subchronic oral toxicity in
       rats or dogs.  However, the requirement for subchronic studies in
       the rodent and  non-rodent will be waived if the required chronic
       studies are acceptable.

    Chronic Effects

       Sprague-Dawley  Rats  - 18 Months:  NOEL for cholinest erase activity
       is 15 mg/kg/day ( supplementary data).

                                   -3-  '

       Beagle Dogs - 2-Year:  NOEL for source A*  ethephon was 7.5 mg/
       kg/day (supplementary data).

       Swiss Albino Mouse - 18-Month oncogenicity study:  NOEL for RBC
       c hoi in est erase activity is < 4. 5mg/kg/day  which was the lowest
       dose tested (LOT) (supplementary data).


       The available data are not adequate to assess  the oncogenic potential
       of ethephon.  In the rat and mouse studies submitted, only chronic
       effects were observed and these effects are discussed  under the
       chronic toxicity section.


       Rat:  NOEL for maternal and embryo/fetal toxicity is 600 mg/kg/day.
             NOEL for teratogenic effects is 600  mg/kg/day.

       Rabbit:  NOEL is 50 mg/kg/day based on fetal resorptions at
                higher dose levels tested.

       Reproduction:  No adequate data available.

       Mutagenicity:  Salmonella typhimurium indicate no mutagenic effect
          up to 1000 ug/100 uL without activation.  No acceptable data
          are available for chromosomal -aberrations,  primary DNA damage,
          or other genotoxic effects.

       Metabolism:  A rat metabolism study is required.

       Possible Presence of Contaminant of lexicological Concern

          The Agency finds that residues of moncchloroacetic acid may be
          found in ethephon-treated commodities.   Monochloroacetic acid
          is a potential degradation product of an impurity in ethephon,
          monochloroethyl ester of (2-chloroethyl)-phosphonic acid.
          Monochloroacetic acid is an extrenely toxic metabolic inhibitor
          and has been prohibited from addition to food under 21 CFR
          189.155.  Analysis of certain food and  feed crops for residues
          of this contaminant are required.

    Major Routes of Exposure

       Dermal, Inhalation

    Physiological and Biochemical Behavioral Characteristics:

    Metabolism:  Acceptable metabolism data are available  for plants and
       ruminants.  The residue of concern in plant commodities, ruminant
       tissues and milk is ethephon per se. Additional data are required
       regarding metabolism in poultry tissues and eggs.

* In. the study there were two, apparently different,  sources of the
chemical  tested and reported as source A and source B.

Possible Presence of impurities: Available data indicate that technical
   ethephon products may contain 2-chloroethanol as an impurity.
   2-Chloroethanol is extrenely toxic via the inhalation route and
   has caused human deaths.   Because of its volatility, 2-choroethanol
   is unlikely to be present  in ethephon end use products in amounts
   high enough to pose an inhalation hazard.  However, the impurity
   could pose a hazard when technical or manufacuring use products
   are stored or used in poorly ventilated spaces.,  Under these
   conditions, 2-chloroethanol  vapors could accumulate to levels
   which may be hazardous to  workers in the area.  The Agency is
   requiring submission of product chemistry data to assess the
   extent of hazard posed by  2-choroethanol.

Environmental Characteristics;

Preliminary Adsorption and Leaching  Characteristics:  Data are required
   on leaching, volatility, and hydrolysis of ethephon to characterize
   the potential to reach ground water.

Ecological Cha rac t eri stic s;

Data are sufficient to characterize  ethephon as slightly toxic to
   birds (Lc50 804 mg/kg quail, 3750 ppm ducks).  Laboratory and
   field studies indicate that  ethephon is slightly toxic to fish
   (Lc50 180 mg/L bluegill, 170 mg/L trout (average)).

Tolerance Assessment;

List of crops and Tolerances:  (CFR  40 180.300)

        Commodity              Tolerance (ppm)

        Apples                      5
        Barley, grain               2.0
        Barley, straw               10.0
        Blackberries                30
        Blueberries                 20
        Cantaloupes                 2
        Cattle, meat byproducts     0.1
        Cattle meat                 0.1
        Cattle fat                  0.1
        Cherries                    10
        Coffee beans                0.1 (N)
        Cottonseed                  2.0
        Cranberries                 5
        Cucumbers                   0.1
        Figs                        5
        Filberts                    0.5
        Goats, fat                  0.1
        Goats, mbyp                 0.1
        Goats, meat                 0.1

  Coircnodity              Tolerance (ppm)

  Grapes                       2.0
  Hogs, fat                    0.1
  Hogs, mbyp                   0.1
  Hogs, meat                   0.1
  Horses, fat                  0.1
  Horses, mbyp                 0.1
  Horses, meat                 0.1
  Lemons                       2
  Macadamia nuts               0.5
  Milk                         0.1
  Peppers                     30
  Pineapples                   2
  Pineapple fodder             3
  Pineapple forage             3
  Pumpkins                     0.1
  Sheep, fat                   0.1
  Sheep, mbyp                  0.1
  Sheep, meat                  0.1
  Tangerines                   0.5
  Tangerine hybrids            0.5
  Tomatoes                     2
  Walnuts                      0.5
  Wheat, grain         .        2.0
  Wheat, straw         '•       10.0
  Guavas                       0.1
  Sugarcane Hawaii only        0.1

40 CFR 185.2700 and 186.2700 (food and feed additive)

  Barley milling fractions
    except flour               5.0
  Wheat milling fractions
    except flour               5.0

  Raisins                     12.0

  Raisin waste                65.0

  Sugarcane molasses           1.5

  Barley milling fractions
    except flour               5.0

  Wheat milling fractions
    except flour               5.0

    Results of Tolerance Assessment: The PADI for ethephon has
       recently been  revised by the Agency ADI Committee and  is
       now established at 0.005 mg/kg/day (0.5 mg/kg/day for  a
       LEL, and an uncertainty factor of 100).  This value is
       based on an LEL of 0*5 mg/kg/day for a decrease in
       plasma choiinesterase activity in a 16-day study in
       humans.  An uncertainty factor of 100 is derived from  a
       factor of 10 for  the variation in the susceptibility of
       humans, and a  factor of 10 for the use of an LEL instead
       of a NOEL.   The PADI will be reevaluated when the required
       toxicity and residue chemistry data are submitted and

4.  Label warning Statements:

       All Manufacturing-Use Products

            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 permit.  Do
            not discharge effluent containing this product to
            sewer systems without previously notifying the
            sewage treatment plant authority.  For guidance
            contact your-.State Water Board or Regional Office
            of the EPA.

            Technical grade ethephon must be stored and used  in
            ventilated areas only.

       End-Use Products

            Do not apply directly to water or wetlands (swamps,
            bogs, marshes, and potholes).  Do not contaminate
            water when disposing of equipment washwaters.

            Mixers, loaders and applicators must wear a full
            face shield, long trousers, long sleeved shirt,
            gloves, and  boots to avoid as much skin and eye
            contact as possible.

            Do not enter treated fields within 24-hours after

            The following interim pre-harvest intervals  (PHI)
            must be included on  end use product labels for the
            raw agricultural commodities listed.  These interim
            PHI's may be revised after the  required field residue
            data have been submitted and evaluated.

       Apples minimum 7 days, barley 40 days, blackberries and
       blueberries 42 days, cherries minimum 7 days, coffee
       beans 14  days, cotton 14-21 days, cranberries  17-21 days,
       cucumbers 17-21 days, figs 14 days, filberts 7  days,
       grapes 14 days, guavas 7 months, melons 2 days, peppers
       14 days,  pineapples 2 days, tangerines 5-10 days,
       tomatoes  14-20 days for processing and 3-6 days fresh
       market California only, walnuts 5-10 days, wheat 40 days.
6.  Summary of  Regulatory Positions

       1.   Ethephon does not meet any of the criteria specified
       in  40 CFR 154.7; therefore a Special Review is not
       being initiated at this time.

      2.   The Agency will not require restricted use classification
      for  ethephon end-use products.

      3.   The Agency is deferring decisions concerning ethephon1 s
      potential for contaminating ground water until information
      on its environmental characteristics and fate have been
      submitted and and reviewed.

      4.   The Agency has identified certain data that will
      receive immediate review when submitted.

      5.   The Agency has determined that foliar and soil dislogeable
      residue data are required to establish reentry intervals
      for  all crops.  An interim reentry interval of 24 hours
      is being  imposed for all crops until final reentry reentry
      intervals are established.

      6.   Pre-harvest intervals are required on product labeling
      for  a variety of currently registered use sites.

      7.   The Agency is requiring data on animal metabolism
      as well as storage stability studies and residue studies for
      poultry and eggs.  In order to remain in compliance with FIFRA,
      registrants must do one of the following:

          a.  Submit data which demonstrate that no residues
      remain in eggs and poultry as a result of feeding treated

          b.  Propose tolerances and provide appropriate
      supporting data for residues in poultry tissues and  eggs.


8.  Additional residue data, including processing data,
must be submitted for  the following raw agricultural
commodities: peppers,  tomatoes, cucumbers, melons, lemons,
tangerines, apples,  cherries, blackberries, boysenberries,
blueberries, cranberries, grapes, filberts, walnuts,
barley (wheat data may substitute), wheat, (and wheat
straw), coffee beans,  cotton seed, figs, guavas, pineapples,
sugarcane, and tobacco.  For tobacco, pyrolysis data
must be submitted.  If residues concentrate in any of
the processed products,  the appropriate food additive
tolerance(s) must be proposed.  Specific data requirements
may be found in the  data tables.

9.  The Agency is requiring the proposal of either
a tolerance for sugarcane forage or a grazing prohbition
for sugarcane forage.

10.  The Agency has  determined that the following
revisions in the tolerances listed in 40 CFR 180.300 and
21 CFR 193.186 are necessary.

    o  The designation "N"  (negligible) must be
       deleted from  all  tolerances entries.

    o  The commodity "pineapple fodder" must be
       deleted from  40 CFR 180.300.

    o  The tolerance for guava must be added to
       40 CFR 180.300.

    o  The tolerance for raisins must be added to
       21 CFR 193.186.
11.  Product chemistry and  residue data are required
depicting residues of monochloroacetic acid in or on
food and feed commidities following  registered applications
of ethephon.  Monochloroacetic acid  may be a toxic metabolic
residue derived from an impurity in  technical ethephon.

12.  The Agency has identified 2-chloroethanol as a
contaminant of toxicological concern.  The Agency is
requiring data to assess the extent  of contamination
with this substance.  Additionally,   the Agency is requiring
that manufacturing use products  bear a label statement
advising users to store and use  the  product in well-ventilated

     13.  While the data gaps are being filled, currently
     registered manufacturing-use products and end-use products
     containing ethephon as the sole active ingredient nay be sold,
     distributed, formulated, and used in the United States, subject
     to the terms and conditions specified in this Standard.
     Registrants must provide or agree to develop additional data,
     required in the Registration Standard.

          The Agency will issue registrations for substantially
     similar products and new uses will be issued after considering
     the effects on the theoretical maximum residue contribution
     (TMRC) and the maximum permissable intake (MPI).
7.  Summary of Major Data Gaps
                                       Due Date (After Issuance
         Data Required                     of the Standard)

         Product Chemistry                   6-12 Months
         Hydrolysis                               9 Months
         Photodegradation                         9 Months
         Soil Metabolism                         27 Months
         Fish Accumulation                       12 Months
         Rotational Crops                        39 Months
         Leaching and Adsorption/                 12 Months
         Terrestrial Field Dissipation            27 Months

         Acute Estuarine and  Marine              12 Months
         Acute Inhalation                         9 Months
         Reproduction                            39 Months
         Mutagenicity                            12 Months
         Animal Metabolism                       18 Months
         Magnitude of Plant Residues          6-24 Months
         Analytical Methods                      15 Months
         Storage Stability                       18 Months
         Chronic Toxicity Rodent                   9 Months*
         Oncogenicity data                        9 Months*

*These studies may be upgraded or  they will have to be repeated.


6.  Contact Person at EPA

       Robert J.  Taylor
       Product Manager 25
       Fungicide-Herbicide Branch
       Registration Division (TS-767C)
       Office of  Pesticide Programs
       Environmental Protection Agency
       401 M Street SW.
       Washington, DC  20460
       (703) 557-1800

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