United States           Office of Pesticides and Toxic Substances
                 Environmental Protection      Office of Pesticide Programs (TS-766C)
                 Agency              Washington. DC  20460
                                                        540/FS-88-114 I
v>EPA      Pesticide
                 Fact Sheet
                 Name of Chemical:    2,4-Dichlorophenoxyacetic Acid  (2,4-D
                 Reason for Issuance:   Registration Standard
                 Date Issued:         September  1988
                 Fact Sheet Number:   94.2
      DESCRIPTION OF CHEMICAL

      Generic Name:  2,4-Dichlorophenoxyacetic Acid

      Common Name:   2,4-D (includes parent acid as well as salt,
                    amine and ester derivatives)

      Trade Name:  2,4-D is available under a large selection of
          trade names, most often formulated as an inorganic salt,
          amine or ester.

      EPA Chemical Code:  030001 (Acid)

      Chemical "Abstracts Service (CAS) Number:  94-75-7 (Acid)

      Year of Initial Registration:   1948

      Pesticide Type:  Herbicide;  Plant Growth Regulator.

      Chemical Family:  Chlorinated phenoxy

      U.S. and Foreign Producers:   2,4-D technical products are
          manufactured by a large number of companies, both U.S.
          and foreign.
     Registered Uses:   Terrestrial,  food and nonfood; aquatic,
          food and nonfood;  domestic; and forestry.

     Predominant Uses:   Postemergent weed control in agricultural
          crops (approximately 57 percent of total usage;  over  45
          percent of total usage is on wheat and corn; 20  percent
          of total usage on  pastures and rangelands; other major
          crops are sorghum,  other small grains, rice and
          sugarcane);  the remainder  is used on noncrop areas, with
          a small amount used as a plant growth regulator  (in
          filberts, citrus and potatoes).

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Formulation Types Registered:  Granular; amine and ester
     liquids;  aerosol spray (foam).

Methods of Application:  Aerial and ground equipment,
     knapsack sprayers, pressure and hose-end applicators,
     and lawn spreaders.

SCIENCE FINDINGS

Summary Science Statement:  The Agency's Office of Pesticide
     Programs (OPP) has classified 2,4-D as a Group D oncogen
     (not classifiable as to human carcinogenicity) because
     existing data are inadequate to assess the carcinogenic
     potential of 2,4-D.  Accidental human poisoning with
     2,4-D, which resulted in severe neurotoxicity, has been
     reported; adequate neurotoxicity studies are not
     available.   While published data indicate that 2,4-D may
     be teratogenic, an acceptable rat teratology study is
     negative; a study in rabbits is needed.

     2,4-D is often formulated as various esters and amines.
     These formulations may affect the physical
     characteristics, biological activity and environmental
     fate of the-parent compound.  Data are needed on each
     ester and amine before the Agency can completely assess
     2,4-D.

     Although laboratory data demonstrate that 2,4-D is
     mobile in soils, its potential to contaminate
     groundwater is limited by its rapid rate of degradation
     and uptake by target plants.  However, residues of 2,4-D
     have been detected in groundwater, mostly from point
     sources, such as mixing, loading and disposal.

     Certain formulations of 2,4-D are highly toxic to fish
     and/or aquatic invertebrates.  Other formulations, for
     which the Agency has data, are in the range of
     moderately toxic to practically nontoxic to nontarget
     organisms.   The Office of Endangered Species has issued
     biological opinions indicating that certain endangered
     species may be in jeopardy from the use of 2,4-D.

Chemical Characteristics  (Acid):

     Physical state - Flakes, powder, and crystalline powder
          and solid
     Color - White to light tan
     Odor - Phenolic to odorless
     Melting point - 135-142°C
     Boiling point - 160°C at 0.4 mm Hg
     Solubility - Soluble in acetone, ethanol, aqueous
          alkali, alcohols, diethyl ether, ethyl ether,

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          isopropanol, methyl isobutyl ketone, most organic
          solvents; insoluble in benzene, petroleum oils
     Vapor pressure - 0.4 mm Hg at 160°C
     Stability - Stable to melting point

Toxicology Characteristics (Acid, except as noted):

Acute Toxicity:

     2.4-D Acid -

     Oral (rat):    639 mg/kg (males); 764 mg/kg (females);
                    Toxicity Category III1

     Inhalation (rat):   1.79 mg/L; Toxicity Category III

     Dermal Sensitization (guinea pig):  Not a sensitizer.

     2f4-D Sodium Salt -

     Oral (rat):    876 mg/kg (males); 975 mg/kg (females);
                    Toxicity Category III

     Dermal (rat):  >2000 mg/kg; Toxicity Category III

     Diethanolamine Salt (Manufacturing-Use Product) -

     Oral (rat):    >2000 mg/kg (males); 1605 mg/kg
                    (females); Toxicity Category III

     Dermal (rabbit):    >2000 mg/kg (males and females);
                         Toxicity Category III

     Inhalation (rat):   >3.8 mg/L; Toxicity Category III

     Primary Eye  (rabbit):  Severe irritation and corneal
               ulcer not resolved 21 days post-treatment;
               Toxicity Category I

     Primary Dermal (rabbit):  No signs of dermal
               irritation; Toxicity Category IV

     Dermal Sensitization (guinea pig):  Not a dermal
               sensitizer.

     Butoxyethyl Ester -

     Oral (rat):    866 mg/kg; Toxicity Category III
     1For a description of Toxicity Categories, see 40 CFR 156.10

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     Dermal (rabbit):     >2000 mg/kg (females:  1829  (mg/kg
                         (males);  Toxicity Category  III

     Inhalation (rat):    >4.6 mg/L;  Toxicity Category III

     Primary Eye (rabbit):   Very mild eye irritation resolved
               in 72 hours;  Toxicity Category III

     Primary Dermal (rabbit):  Very  slight erythema  cleared
               in 72 hours;  Toxicity Category III.

     Dermal Sensitization (guinea  pig):   Was a sensitizer  in
               two tests and not a sensitizer in a third
               test.

     Isooctvl Ester -

     Oral (rat):    982 mg/kg (males); >720 <864 mg/kg
                    (females); Toxicity Category III

     Dermal (rabbit):     >2000 mg/kg; Toxicity Category III

     Isobutvl Ester -

     Oral (rat):    700 mg/kg (males); 553 mg/kg (females);
                    Toxicity Category III

     Dermal (rabbit):     >2000 mg/kg; Toxicity Category III

     Isopropvl Ester -

     Oral (rat):    640 mg/kg (males); 440 mg/kg (females);
                    Toxicity Category II

     Dermal (rabbit):     >2000 mg/kg; Toxicity Category III

     Inhalation (rat):    >4.97 mg/L; Toxicity Category III

     Primary eye (rabbit):   All irritation cleared at 4
          days;:Toxicity Category  III

     Primary dermal (rabbit): No irritation at 72 hours;
                              Toxicity Category IV

     Dermal Sensitization (guinea  pig):   Nonsensitizer

Subchronic Toxicity: No acceptable  data are available on
     2,4-D.  The requirement for subchronic oral studies on
     the acid is waived because chronic studies are  required;
     a subchronic dermal study is  required.  Subchronic
     studies are required for the  esters and amines.

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Chronic Toxicity:

     Oncogenicity (rats):  No observed effects level (NOEL)
          for systemic effects - 1 mg/kg/day; lowest observed
          effects level  (LOEL) for systemic effects - 5
          mg/kg/day; further evaluation needed to determine
          if maximum tolerated dose was reached.

     Oncogenicity (mice):  NOEL for systemic effects - 1
          mg/kg/day; LOEL for systemic effects - 15
          mg/kg/day; further evaluation needed to determine
          if maximum tolerated dose was reached.

     Teratology  (rats):  Fetotoxicity (delayed ossification)
          LOEL 75 mg/kg/day and NOEL 25 mg/kg/day; Maternal
          toxicity NOEL 75 mg/kg/day (highest dose tested).

     Reproduction (rats):  NOEL 5 mg/kg/day.

Major Routes of Exposure:  The major route of exposure is
     dermal; respiratory exposure is negligible.

Physiological and Behavioral Characteristics:

     Foliar Absorption:  2,4-D is absorbed through the roots
          and/or leaves depending upon the type of
          formulation.  A rain-free period of 4 to 6 hours
          usually is adequate for uptake.

     Translocation:   Following foliar absorption, 2,4-D
          translocates within the phloem, probably moving
          with the food material.  Following root absorption,
          it may move upward in the transpiration stream.
          Translocation rate is influenced by the growth rate
          of the plant.  Accumulation occurs principally at
          the rapid growth regions of shoots and roots.

     Mechanism of Pesticide Action:  2,4-D acid stimulates
          nucleic acid and protein synthesis affecting the
          activity of enzymes, respiration and cell division.
          Broadleaf plants exhibit malformed leaves, stems
          and roots.

Environmental Characteristics:

     Absorption and Leaching:  2,4-D is mobile to highly
          mobile in five soil types.  Based on available
          data, aged 2,4-D residues are only slightly mobile.

     Microbial Breakdown:  2,4-D degrades rapidly in aerobic
          silty clay and loam soil systems.

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     Bioaccumulation:  Available data indicate a low
          potential for 2,4-D to accumulate in fish.

     Resultant Average Persistence:   In aerobic silty clay
          and loam soils, 1.9-2.2 percent of applied 2,4-D
          remained at 51 days post-treatment; in four other
          soils, only 0.7-2.5 percent remained at 150 days
          post-treatment.

     Environmental Fate and Surface and Groundwater
          Contamination Concerns:  Although laboratory data
          demonstrate that 2,4-D is mobile in soils, its
          potential to contaminate groundwater is limited by
          its rapid rate of degradation and uptake by target
          plants.  However, residues of 2,4-D have been
          detected in groundwater, mostly from point
          sources, such as mixing, loading and disposal.

     Exposure of Humans and Nontarget Organisms:  Accidental
          human poisoning with 2,4-D, which resulted in
          severe neurotoxicity,  has been reported.  Reports
          have been received concerning off-target movement
          of 2,4-D resulting in damage to crops or other
          desirable plants.

     Exposure during Reentry Operations:  Based on available
          data, 2,4-D products are of low toxicity (Toxicity
          Categories III and IV). Because of these low levels
          of toxicity, reentry is not a concern.

Ecological Characteristics (detailed information can be
     obtained from the Registration Standard):

     Avian Toxicity:  Acceptable data indicate that 2,4-D
          acid can be characterized as moderately toxic to
          practically nontoxic to avian species on an acute
          basis.  Butyl ester can be characterized as
          practically nontoxic on an acute and chronic basis.

     Fish Toxicity:  Acceptable data indicate that 2,4-D acid
          and certain of its salts, esters and amines can be
          characterized in the range of moderately toxic to
          practically nontoxic to fish.  However, the
          compounds N-oleyl-1,3-propylenediamine salt, N,N-
          dimethyloleyl-linoleylamine, butyl ester,
          butoxyethanol ester and propylene glycol butyl
          ether ester can be characterized as highly toxic to
          fish, based on the following toxicity values:

          N-oleyl-l,3-propylene-
               diamine salt   0.3 ppm  (bluegill sunfish)
                              0.8 ppm  (channel catfish)

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     N,N-dimethyloleyl-
          linoleylamine
     Butyl ester
     Butoxyethanol ester
     Butoxypropyl ester
     Propylene glycol
       butyl ether ester
0.64 ppm (rainbow trout)
0.49-2.82 ppm (cutthroat trout)
0.5-2.8 ppm (lake trout)
0.4-0.96 ppm (rainbow trout)
0.29-0.3 ppm (bluegill sunfish)
0.65 ppm (rainbow trout)
0.76-1.2 ppm (bluegill sunfish)
3.3 ppm (fathead minnow)
0.78-1.35 ppm (channel catfish)
5.4 ppm (rainbow trout)

0.33-2.8 ppm (cutthroat trout)
0.39-2.93 ppm (lake trout)
0.95-1.44 ppm (rainbow trout)
0.56-0.67 ppm (bluegill
sunfish)
Freshwater Invertebrates Toxicity:   Of those compounds
     for which the Agency has data, reported toxicity
     values indicate that the compounds can be
     characterized as slightly toxic to practically
     nontoxic, excepted as noted below.  The compounds
     set forth below have toxicity values which
     characterize them as highly toxic to-aquatic
     invertebrates.
     Dimethylamine
     Isooctyl ester
0.15 ppm (grass shrimp)
0
                           5 ppm (waterflea)
     Butoxyethanol ester 1.7-6.4 ppm (waterflea)
                         2.2 ppm (seed shrimp)
                         2.6 ppm (sow bug)
                         0.44-6.1 ppm (side swimmer)
                         0.39-0.79  ppm (midge)
     Propylene glycol
       butyl ether ester 0.1-14 ppm (waterflea)
                         0.42 ppm (seed shrimp)

Estuarine and Marine Organisms Toxicity:   Acceptable
     data are available only for the butoxyethano1 ester
     which report toxicity values of 5.0  mg/L  (longnose
     killifish),  2.6 mg/L (Eastern oyster)  and 5.6 mg/L
     (brown shrimp), which indicate that  the material is
     moderately toxic to estuarine  and marine organisms.

Effects on Plants:  Limited plant protection studies are
     available.  In a spray drift study,  two application
     methods were compared as to quantity and pattern of
     deposition.   No difference was found between the
     amine derivatives (diethanolamine and
     dimethylamine).   With these amines,  drift was
     observed beyond 225 feet from the site of

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          application.  No residues, attributable to drift,
          were found when applied postemergent to wheat or
          corn.

          The toxicity of butoxyethanol ester was tested on
          four species of algae.   Toxicity values ranged from
          75 mg/L to 150 mg/L.

     Nontarget Insects:  There  is sufficient information to
          characterize 2,4-D as relatively nontoxic to honey
          bees, when bees are exposed to direct treatment.

     Potential Problems Related to Endangered Species:  The
          Office of Endangered  Species has determined that
          certain uses of 2,4-D may jeopardize the continued
          existence of endangered species or critical habitat
          of certain endangered species.

Tolerance Assessment:

     Tolerances Established:  Tolerances and food and feed
          additive regulations  have been established for
          residues of 2,4-D in a variety of raw agricultural
          commodities and meat  byproducts (40 CFR 180.142),
          and in processed food (40 CFR 185.1450) and feed
          (40 CFR 186.1450).

     Results of Tolerance Assessment:  A provisional
          acceptable daily intake (PADI) of 0.003 mg/kg/day
          for 2,4-D acid has been established based on a two-
          year rat feeding study.   Compound-related effects
          were observed in the  kidneys of both male and
          female rats.  The LOEL was 5 mg/kg/day and the NOEL
          was 1 mg/kg/day.  An uncertainty factor of 100 was
          used to account for the inter- and intraspecies
          differences.  An additional uncertainty factor of 3
          was used since there is no dog study available and
          no information available that indicates the dog is
          less sensitive than the rat.

Reported Pesticide incidents:  Based on the Pesticide
     incident Monitoring System files, covering the period
     1966 to 1979, reports were received concerning the off-
     target movement of 2,4-D in unspecified formulations,
     esters and amines.  The incidents involved drift from
     aerial (173 reports) and ground  (104 reports)
     applications, as well as volatilization and drift (35
     reports) and resulted in damage to off-target crops or
     other desirable plants.

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SUMMARY OF REGULATORY POSITION AMD RATIONALE

Summary of Agency Position:  OPP has classified 2,4-D as a
     Group D oncogen (not classifiable as to human
     carcinogenicity).   EPA is, however, requiring additional
     data, including additional information on oncogenicity
     and teratogenicity and neurotoxicity studies, for
     further evaluation of 2,4-D.   Data are being required on
     the ester and amine formulations of 2,4-D as well as on
     the acid.  EPA will not establish any significant new
     food use tolerances or register any significant new uses
     at this time.

     Additional data are needed to thoroughly evaluate the
     ecological effects of 2,4-D and its potential to
     contaminate groundwater.

     EPA is developing a program to reduce or eliminate
     exposure to endangered species from the use of 2,4-D to
     a point where use does not result in jeopardy, and will
     issue notice of any labeling revisions when the program
     is developed.  Endangered species labeling is not
     required at this time.

Unique Warning Statements Required on Labels:

     Manufacturing-Use Products;  "Do not discharge effluent
          containing this product into lakes, streams, ponds,
          estuaries, oceans, or public waters 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."

     End-Use Products;

     Aquatic Uses.  "Drift or runoff may adversely affect
          nontarget plants.  Do not apply directly to water
          except as specified on this label.  Do not
          contaminate water when disposing of equipment
          washwaters."

     Nonaauatic Uses.  "Drift or runoff may adversely affect
          nontarget plants.  Do not apply directly to water
          or wetlands (swamps, bogs, marshes, and potholes).
          Do not contaminate water when disposing of
          equipment washwaters."

     End-Use Products - Certain Formulations;  End-use
          products containing the following formulations must

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     contain the above environmental precautions
     modified to indicate that the product is toxic
     either to fish or aquatic invertebrates:

     Toxic to Fish - N-01eyl-l,3-Propylenediamine salt
                     N,N-Dimethyloleyl-Linoleylamine
                     Butyl ester
                     Butoxylethanol ester
                     Propylene glycol butyl ether ester

     Toxic to Aquatic Invertebrates - Dimethylamine
                                      Isooctyl ester

All End-Use Products;  The following statements are
required in the use directions for all end-use products:

Liquid Formulations;  "This product can reach
     groundwater from mixing and loading.  To minimize
     groundwater contamination from spills during
     mixing, loading and cleaning of equipment, take the
     following steps:

     "Mixing and Loading;  When mixing, loading or
     applying this product, wear chemical resistant
     gloves.  Wash nondisposable gloves thoroughly with
     soap and water before.removing.

     "The mixing and loading of spray mixtures into the
     spray equipment must be carried out on an
     impervious pad  (i.e., concrete slab, plastic
     sheeting) large enough to catch any spilled
     material.  If spills occur, contain the spill by
     using an absorbent material (e.g, sand, earth or
     synthetic absorbent).  Dispose of the contaminated
     absorbent material by placing in a. plastic bag and
     following disposal instructions on this label.

     "Triple rinse empty containers and add the rinsate
     to the mixing tank.

     "Cleaning of Equipment;  When cleaning equipment,
     do not pour the washwater on the ground; spray or
     drain over a large area away from wells and other
     water sources."

Granular Formulations;  "This product can reach ground-
     water from improper handling.  To minimize ground-
     water contamination from spills during loading and
     cleaning of equipment, take the following steps:

     "Handling;  When handling this product, wear
     chemical resistant gloves.  Wash nondisposable

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          gloves thoroughly with soap and water before
          removing.  If spills occur, collect the material
          and dispose of by following disposal instructions
          on this label.

          "Cleaning of Equipment;  When cleaning equipment,
          do not pour the washwater on the ground; spray or
          drain over a large area away from wells and other
          water sources."

     End-Use Products - Certain Food/Feed Uses.  Labels for
          products registered for certain food/feed uses must
          contain revised use directions pertaining to
          appropriate preharvest, pregrazing and preslaughter
          intervals; allowable range of diluent; and/or
          maximum seasonal application rate and/or number of
          applications.

SUMMARY OF MAJOR DATA GAPS.  The following data are required
for 2,4-D acid.  The Agency is also requiring data on each
individual ester and amine of 2,4-D.  Specific requirements
are detailed in the Data Tables, Appendix I of the
Registration Standard, which can be obtained from the Product
Manager listed below.

     Study                                   Due Date - From
                                             Date of Standard

     Product Chemistry                       6-15 months

     Residue Chemistry:                      18-24 months
       Plant and animal metabolism
       Analytical methods
       Residue studies

     Toxicology:                     .        9-50 months
       Primary Eye and Dermal Irritation
       21-Day Dermal
       Chronic Toxicity (nonrodent)
       Teratogenicity (rabbit)
       Mutagenicity
       Metabolism
       Special Dermal (Neurotoxicity)
       Reserved:  Oncogenicity (two species)

     Ecological Effects:                     9-18 months
       Avian Dietary
       Aquatic Organism (freshwater fish
          and invertebrates; estuarine
          and marine organisms; accumulation)
       Phytotoxicity (Tier II)
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     Study
Due Date - From
Date of Standard
     Environmental Fate:                     9-50 months
       Hydrolysis
       Photodegradation (water, soil,- air)
       Metabolism (anaerobic soil; aerobic
          and anaerobic aquatic)
       Leaching and Adsorption/Desorption
       Volatility (lab and field)
       Dissipation (soil, aquatic and forestry)
       Accumulation (confined rotational
          crops; irrigated crops; fish
          and aquatic nontarget organisms)
       Spray drift

CONTACT PERSON AT EPA;   Mr. Richard Mountfort
                         Product Manager  (Team 23)
                         Fungicide-Herbicide Branch
                         Registration Division (TS-767C)
                         Office of Pesticide Programs, EPA
                         Washington, DC  20460

                         Telephone:  (703) 557-1830

nTSfT.ATMF.R!  The information in this Pesticide Fact Sheet is
a summary only and may not be used to fulfill data
requirements for pesticide registration and reregistration.
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