United States               Office of Pesticides and Toxic Substances
       Environmental Protection         Office of Pesticide Programs (H7508C)
       Agency                   Washington, DC 20460
•4>EPA    Pesticide
                    Fact   Sheet
                                   540/FS-89-070
       Name of  Chemical:  HCPA

       Reason for Issuance:  REGISTRATION STANDARD (SRR)

       Date Issued:  SEP 2 2 1989
       Fact Sheet  Number: 203
Description of Chemical

Generic name:  2-methyl-4-chlorophenoxyacetic acid, and
             its sodium salt, esters and organic amines

Common name:  MCPA

Trade names:  ACME MCPA AMINE 4, AGRITOX, AGRO ONE,
            BORDERMASTER,  BH MCPA, CHIPTOX, BED-WEED,
            EMPAL, KILSEM, MEPHANAL, METHOXONE, PHOMENE,
            RHONOX, and WEEDAR

EPA Pesticide Chemical (Shaughnessy) Number:

     MCPA acid - 030501
     Sodium salt - 030502
     Diethanolamine salt -  030511
     Dimethylamine salt - 030516
     Butoxyethyl Ester - 030553
     Isobutyl Ester - 030562
     Isooctyl Ester - 030563
     Isopropyl Ester - 030566

Chemical Abstracts Service (CAS) Number:

     MCPA acid - 94-74-6

Year of Initial Registration: 1973

Pesticide Type:  Herbicide

Chemical Family: Phenoxy herbicides

U.S. Registrant: Dow Chemical

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2.   Use Patterns and Formulations

    Application sites:   Terrestrial food crop use on small grains   f
      (wheat, oats, barley,  rye), peas,  beans, pasture grasses,
      grain sorghum, alfalfa and clovers.

      Terrestrial nonfood crop use on homelawns,  ornamental turf,
      flax, grass seed crops,  noncrop areas,  pasture grasses,
      rangeland grasses, and forestry.

      Aquatic food use on rice.

      Aquatic nonfood use on aquatic weeds.

    Formulations:  Granular  (MCPA acid and isooctyl  ester) ;
     soluble concentrate/liquid (sodium salt, diethanolamine
     salt, dimethylamine salt);  Technical (MCPA acid, Butoxyethyl
     ester, isooctyl ester); Formulation Intermediate (Butyl
     ester, isobutyl ester,  isopropyl ester,  dimethylamine salt,
     MCPA acid); Ready-To-Use (Dimethylamine  salt);  and
     Emulsifiable Concentrate (Butoxyethyl ester, isooctyl
     ester).  There are 117  federally registered products
     containing MCPA as an active ingredient  either  by itself  or
     itself or in combination with other pesticides.

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

    Application rates:   0.2  - 3.0 Ib active ingredient per acre.

    Mode of activity:  MCPA  is absorbed through both leaves and
     roots and is readily translocated throughout the plant.
     MCPA stimulates nucleic acid and protein synthesis affecting
     the activity of enzymes,  respiration and cell division.
     Broadleaf plants exhibit malformed leaves, stems and roots.

3.   Science Findings

    This review of MCPA^acid,  its salts, and esters, is the
second intensive evaluation  of the compound.   In its original
Registration Standard, issued in 1982, the Agency summarized the
available data supporting the registration of MCPA and concluded
that additional data were needed to fully evaluate the pesticide.
The Agency has since received and reviewed the data  on these
compounds.

     The Agency has registered 9 salts, esters and amines of MCPA
in addition to the acid.  From a toxicological standpoint the
acid and the sodium salt are essentially identical.   The

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registrants, however, must show that the other derivatives would
be equivalent to MCPA acid under testing conditions.  Otherwise,
a complete set of data must be submitted on each derivative to
support their continued registration.  The following scientific
assessment discusses the Agency's knowledge on MCPA acid.  If the
data refers to a derivative, the derivative is identified.

    Chemical/Physical Characteristics of the Technical Material

          MCPA is white to light brown and can be a solid,
    flakes, crystal powder or liquid.  It has no odor or can be
    slightly phenolic smelling.   The melting point is 114 to
    119°C  and is  soluble to varying degrees  in various  solvents.

    Toxicology Characteristics

      Acute Oral.  Toxicity Category III (LD50  1.38 g/kg  in male
        rats, 0.76 g/kg in female rats).

      Acute Dermal.  Toxicity Category III (LD50 > 4000 mg/kg in
        the rat).

      Acute Inhalation.  Toxicity Category III (LC50 > 6.36 mg/L
        in the rat).

      Primary Eye Irritation.  Toxicity Category I (corneal
        opacity with irritation of conjunctive observed 21 days
        post-instillation with rabbits).

      Skin Sensitization.  Not a skin sensitizer in guinea pigs.
        Testing on other species required.

      Acute Delayed Neurotoxicity.  MCPA is not an
        organophosphate, therefore a study is not required.

      Subchronic Oral.   Sufficient data are available to satisfy
        the requirements of a subchronic oral study in rodents
        and nonrodents.  In beagles there was evidence of dose-
        related liver and kidney toxicity.   A NOEL for systemic
        effects was set at 1 mg/kg/day.  In rats, the mid- and
        high-dose males exhibited increased kidney weights and
        both sexes had indications of kidney disfunction.
        Hepatotoxicity, based on prolongation of clotting times
        and decreased cholesterol concentrations occurred in high
        dose males.  The NOEL for systemic effects is set at 2.5
        mg/kg/day.

      Subchronic Dermal.  Data gap.  A 21-day dermal toxicity
        study is required.

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Chronic Toxicity.  Sufficient data are available to satisfy
  the requirements for the chronic feeding studies in two
  species for technical MCPA acid.  In beagles, after one
  year, kidney and liver toxicity was observed at the mid-
  and high dose levels.  The systemic NOEL was set at 0.15
  ing/kg/day, LDT.

  In a 2 year rat study, hepatotoxicity was observed with
  elevated triglycerides, decreased cholesterol, and kidney
  nephropathy.  The NOEL for systemic toxicity was set 1.0
  mg/kg/day.

Oncogenicity.  Rat and mouse studies were reviewed and
  found acceptable.  MCPA is considered to be non-
  oncogenic.  No additional studies are required.

Teratogenic.  The studies available to the Agency are
  unacceptable under current guideline requirements.  While
  these studies showed no developmental alterations, the
  Agency is requiring teratology studies in two species.

Reproduction.  In a two-generation reproduction study with
  rats, there were indications of a potential postnatal
  growth effect.  The NOEL is set at 7.5 mg/kg/day.  No
  additional reproduction studies are required.

Mutaaenicity.  The Agency has data to satisfy the
  Structural Chromosomal Aberration study and.the DNA
  Damage and Repair study.  MCPA acid was found to be non-
  mutagenic in the first study and weakly mutagenic in the
  second.  The Agency is requiring a gene mutation study.

Metabolism.  In a rat study, MCPA did not appear to be
  significantly metabolized in vivo (82 and 88% were
  recovered in male and female rat .urine, respectively).
  Repeat dosing did not generally indicate biŠaccumulation
  in any site except the kidney, primarily in male rats.
  Fat appeared to be the site for some MCPA sequestration.
  No additional metabolism studies are required.

Special Neurotoxicity Testing.  MCPA is structurally
  related to 2,4-D which is suspected of causing neuropathy
  in humans.  Special neurotoxicity testing of 2,4-D is
.  currently required.  Because of this structural
  similarity to 2,4-D, the Agency is also requiring special
  neurotoxicity testing of MCPA.

Toxicology Profile of Other MCPA Formulations.   As stated
  previously from a toxicological standpoint one may expect
  the acid and sodium salt to be identical.  The organic

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    amines and esters may be significantly different and
    lacking data to show otherwise, may have different
    toxicological properties.  The major exposure to these
    compounds is during application therefore acute
    toxicology data are required on the various derivatiyes.
    The Agency has some acute testing on these derivatives
    and they fall in toxicity Category III.  Additional acute
    testing is required.

  Human Exposure.   The greatest potential for direct human
    exposure comes during mixing and loading operations.
    Exposure would be minimized by wearing of protective
    equipment.  The Agency is requiring protective eyewear
    for mixers, loaders, and home users of MCPA acid
    products. No specialized protective language other than
    those required in 40 CFR 156 is required for other MCPA
    derivative homeowner use products.  There have been no
    poisoning incidences with MCPA reported in California
    since 1974.  Reentry data are not required since MCPA is
    generally in Toxicity Category III for acute studies.

  Environmental Characteristics.  Preliminary data have shown
    that MCPA degrades under aerobic laboratory conditions
    with a half-life of less than a week to 50 days.  Under
    aerobic conditions 89% of parent MCPA remained undegraded
    for 374 days.  MCPA is stable to hydrolysis and to
    photolysis in soils.  MCPA salts are highly stable in
    water.  Available data are insufficient to fully assess
    the environmental fate of MCPA and its various
    derivatives.

  Groundwater Concerns.   MCPA appears to be mobile from
    preliminary leaching studies.  MCPA was found,in well
    water in Missouri.  Groundwater contamination appears to-
    be associated with point sources.  A special groundwater
    precautionary statement on labels is being imposed.

Ecological Effects

      Based on available data, MCPA acid has been determined
to be moderately toxic to avian species, slightly toxic to
freshwater fish, practically nontoxic to freshwater
invertebrates and estuarine and marine organisms.  Additional
ecological effects data are required on MCPA and its
derivatives.  The following data comes from acceptable
studies:

      o  Acute LD50 377 mg/kg for Bobwhite quail

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      o  Dietary LC50 > 2000 ppm for mallard, bobwhite, and
           ring-necked pheasant

      o  LC50 rainbow trout = 89 ppm

      o  LC50 bluegill = 97 ppm

      o  LC50 Daphnids > 180 ppm

      o  LC50 Atlantic silverside = 179 ppm

      o  LC50 Oyster Larvae = 155 ppm

  Effects on Plants.  The Agency has no data for toxicity to
    nontarget plants.  A complete battery of tests are
    required using MCPA and all its derivatives.

  Potential Problems Related to Endangered Species.  Because
    of MCPA's demonstrated toxicity to nontarget species and
    its intended use pattern, several endangered species
    could be put at risk from the application of MCPA acid
    and its derivatives.   The Agency has proposed a
    comprehensive Endangered Species Protection program
    (Federal Register 54(126) July 3, 1989).

  Nontarget Insects.  MCPA acid and its sodium salt
    derivative are relatively nontoxic to honeybees.  Data
    are required on the dimethylamine salt and isooctyl ester     ,
    as their use patterns allow for significant potential         "
    exposure to bees.

  Product Chemistry.  The Agency is requiring that all
    product chemistry data be. resutmitted.  Further, MCPA may
    be contaminated with dioxins or dibenzofurans, and the
    amine salts of MCPA may be contaminated with n-
    nitrosamines.  Therefore, analytical data, are required
    for certain products.

Tolerance Assessment

     Tolerances for residues of MCFA per se in or on food and
feed commodities are published in 40 CFR 180.339(a).
Tolerances for residues of MCPA and its metabolite 2-methyl-
chlorophenoxyacetic acid in or on animal commodities are
published in 40 CFR 180.339(b).

     The residue data reviewed in support of these tolerances
showed the following:

     - Data on metabolism of MC'PA in plants available  for

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review in the 1982 document indicated that MCPA is readily
taken up and translocated by plants.  Additional data are
required on the identity and quantities of residue in or on
plants.  The nature of the residue is not adequately
understood.

    - Data pertaining to the residues of MCPA in animals were
reviewed for the 1982 document.  That document did not
require additional data on animal metabolism.  Current
Guidelines specify that terminal residues in animals be
identified and quantified using radioactive material.  The
metabolism of MCPA in animals is not adequately understood
and additional data are required.

    - The current residue analytical methods in PAM I are
adequate for enforcement of tolerances for residues in plants
and animals.

    - Data depicting the stability of MCPA residues in
storage were not required in the 1982 document.  Current
Guidelines specify that storage stability data must be
submitted in support of established tolerances.

    - There are available data to support the established
tolerances for MCPA in or on canarygrass seed and straw.

       Additional residue data are required on dried beans,
peas (succulent and dry), pea vines and hay, rice grain,
sorghum grains, wheat grains, rice straw, sorghum forage and
fodder, wheat straw, annual canarygrass, pasture and
rangeland grasses, grass hay, alfalfa and alfalfa hay,
flaxseed, and flax straw.

    - The data requested on wheat grain, forage, and straw
may, by translation, support the established tolerances for
residues of MCPA in or on the grain, forage, and straw of
barley, oats, and rye.  The data requested on alfalfa and
alfalfa hay may, by translation, support the established
tolerances for residues of MCPA in or on clover and clover
hay, lespedeza and lespedeza hay, trefoil and trefoil hay,
and vetch and vetch hay.

       Processing data are needed on rice grain, sorghum
grain, wheat grain, and flaxseed.  The requirements for
processing data on barley, oat, and rye grain may be
satisfied by the data requested on wheat.

    - Tolerances need to be proposed for residues of MCPA in
or on bean vines and hay, barley hay, oat hay, rye hay, wheat
forage and hay, and canarygrass forage.

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        - Upon receipt of the data requested on animal  metabolism
    and livestock feed items, the established tolerances for the
    combined residues of MCPA and 2-methyl-4-chlorophenol in the
    meat, fat, and meat by-products of cattle,  goats, hogs,
    horses, and sheep and in milk will be  assessed and  the need
    for tolerances for residues in poultry tissues and  eggs  will
    be determined.

        - A provisional acceptable daily intake (PADI,  RfD)  of
    0.0015 mg/kg/day for MCPA has been established based on  a 1-
    year feeding study (dog, NOEL 0.15 mg/kg).   The value given
    is a PADI because of the teratology data gaps.   However, when
    the teratology studies are submitted and found acceptable,
    they are not expected to greatly alter the RfD calculations.
    A safety factor of 100 was utilized.   The dietary exposure
    was calculated using the published tolerances  in 40 CFR
    180.339.  A dietary exposure for the U.S.  population is
    calculated to be 0.001547 mg/kg/day,  corresponding  to 103
    percent of the RfD.  The population subgroups  with  the
    highest calculated exposure were nonnursing infants (0.007405
    mg/kg/day, 493% of the RfD) and children 1 to  6 years of age
    (0.004069 mg/kg/day, 271% of the RfD).  A dietary exposure
    was also conducted using the published tolerances factored by
    the percent of crop treated with MCPA.  The dietary exposure
    for the U.S. population is then 10% of the RfD, for
    nonnursing infants, 51% of the RfD, and for children 1 to 6
    years of age, 27% of the RfD.

4.   Summary of Regulatory Positions and Rationales

    ..-  MCPA is not a candidate for special review.

    -  MCPA does not meet the criteria for restricted use
       classification.

       Precautionary labeling is required to minimize any hazard
       to nontarget organisms.

       The Agency is requiring data on MCPZv acid as well as  its
       derivative amines and esters.

    -  A special groundwater warning statement is  required on the
       label because of MCPA's potential to contaminate these
       waters.

    -  MCPA does not meet the criteria to require  a reentry
       interval.

       The Agency will consider establishment of significant new
       food use tolerances for MCPA.

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Required Unique Labelina
A.  Groundwater Advisory Statements
B.  Environmental Hazards Statement
C.  Feeding and/or Grazing Restrictions
D.  Protective Clothing .Statement
E.  Nontarget Species Precautionary Statements

Summary of Outstanding Data Requirements
Toxicology
Environmental Fate/Exposure
Ecological Effects
Residue Chemistry
Product Chemistry
Timeframe Ranges

1-4 years
1-4 years
2 years
2-4 years
1-2 years
Contact Persons at EPA

Product Specific Inquiries;
Joanna Miller
Acting Product Manager (23)
Fungicide Herbicide Branch
Registration Division (H-7505C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, s.W.
Washington, B.C.  20460

Office location and telephone number:
Room 245, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA  2202
(703) 557-1800

Reregistration Standard Document Inquiries;
Philip T. Hundemann
Review Manager
Reregistration Branch
Special Review and Reregistration Division (H-7508C)
Environmental Protection -Agency
401 M Street, S.W.
Washington, D.C.  20460

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    Office location and telephone number:
    Room 1124, Crystal Mall #2
    1921 Jefferson Davis Highway
    Arlington, VA  22202
    (703) 557-0933
DISCLAIMER:  The information in this Pesticide Fact Sheet is a
summary only and is not be used to satisfy data requirements for
pesticide registration and reregistration.  The complete
Reregistration Document for the pesticide may be obtained from
the National Technical Information Service.  Contact the Review
Manager listed above for further information.
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