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trichlorfon (Dipterex, Dylox) Chemical Fact Sheet 6/84

                        CHEMICAL FACT SHEET FOR:


DATE ISSUED: June 30, 1984

                   1.  DESCRIPTION OF CHEMICAL

- Generic Name:  dimethyl-(2,2,2-trichloro-1-hydroxyethyl) phosphonate
- Common Name:  Trichlorfon
- Trade Names:  Trichlorphon, Trichlorofon, Chlorphos, Bay 13/59,
  Anthon, Bovinox, Briten, Cekufon, Ciclosom, Crinex, Danex, Dipterex,
  Dylox, Equinoaid, Neguvon, Proxol, Trinex, Tuzon, and Leivasom.
- EPA Shaughnessy Code:  057901
- Chemical Abstracts Service (CAS) Number:  52-68-6
- Year of Initial Registration:  1960
- Pesticide Type:  Insecticide
- Chemical Family:  Organophosphate
- U.S. and Foreign Producers:  Mobay Chemical Corp., Intrachem, S.A.,
  Aceto Chemical Co., Inc., and Makhteshim Beer-Sheva Chemical Works


- Application sites:  vegetable, fruit and field crops  livestock;
  ornamental and forestry plantings; in agricultural premises and
  domestic dwellings; in greenhouses, and for control of parasites on
  fish in designated aquatic environments.
- Types of formulations:  soluble concentrate, dust, granular, liquid,
  wettable powder/dust, pellets/tablets, and ready to use liquids.
- Types of methods of application:  aerial and ground application as a
  spray, dust, granular, pellet or tablet.
- Application rates:  0.125-8.0 lbs/acre
- Usual carriers:  Confidential Business Information
- Efficacy review results:  none conducted

                     3.  SCIENCE FINDINGS

Chemical Characteristics

   Technical trichlorfon is a white crystalline solid with a melting 
point of 81-82 degrees C.  The boiling point for technical trichlorfon 
is 100 degrees  C at 0.1 mm Hg and the vapor pressure is 7.8 mm Hg at 20 
degrees C.  The empirical formula is C4H804C13P and the molecular weight 
is 257.6.  Trichlorfon is soluble in water (9% at 20 C), alcohols, 
methylene chloride and ketones and slightly soluble in aromatic 

Toxicological Characteristics

- Current available toxicological studies on trichlorfon are as

- Acute oral toxicity:  rat, 450 mg/kg; mouse, 940 mg/kg 
  (Tox Category II)
- Acute dermal toxicity: rat, LD50 >2 gm/kg (Tox Category III)
- Primary eye irritation, primary dermal irritation, dermal sensiti-
  zation, acute inhalation, and subchronic feeding are data gaps.
- Additional data are needed to fully assess the toxicity of
- Major routes of exposure:  Application by ground and aerial
  equipment increases the potential for exposure of humans, livestock
  and wildlife due to spray drift.  Human exposure to trichlorfon from
  handling, application and reentry operations would be minimized by
  the use of approved respirators and other protective clothing.

Physiological and Biochemical Characteristics

- Mechanism of pesticidal action:  stomach and/or contact poison.
- Metabolism and persistence in plants and animals is not adequately
  understood and the residues of concern cannot be ascertained.

Environmental Characteristics

   Trichlorfon degrades rapidly in aerobic soils (half-lives 
approximately 1-27 days) under nonsterile conditions, but in sterile 
soils trichlorfon is stable (half-life >40 days).  Trichlorfon also 
degrades rapidly (approximately 99% of applied degraded in 2 hours) in 
alkaline pond water (pH 8.5) at room temperature. but remains stable in 
the same pond water held under acidic (pH 5.0) conditions for 2 hours.  
The major degradate in both soil and pond water is DDVP (dimethyl 2,2-
dichlorovinyl phosphate) with desmethyl DDVP also reported as a 
degradate in soil.  Trichlorfon is very mobile in soils varying in 
texture from sand to silty clay with organic matter contents of 0.5-
5.1o/0.  Therefore, soil organic matter content does not appear to 
influence or only negligibly influences trichlorfon mobility in soil. 
The potential for groundwater contamination by the parent compound may 
be mediated by its degradation in soil; however, the potential for 
groundwater contamination by degradates of trichlorfon cannot be 
assessed due to the absence of an aged leaching study. Forestry and 
aquatic field dissipation studies did not show a potential for 
trichlorfon to persist in leaves, leaf litter, soil, water or sediment 
(and mud), nor did they show a potential for trichlorfon to accumulate 
in nontarget fish.

Ecological Characteristics

- Acute avian oral toxicity:  40-47 mg/kg
- Avian subacute dietary toxicity:  720-3401 ppm
- Freshwater fish acute toxicity:  1.6-180 ppm
- Acute toxicity for freshwater invertebrates:  .18-7300 ppb
- Based on studies available to assess hazards to wildlife and aquatic
  organisms, technical trichlorfon is characterized as highly toxic to
  both cold water and warm water fish, very highly toxic to freshwater
  invertebrates and highly toxic to birds.  Label precautions required
  by this Guidance Document should reduce the hazard to wildlife and
  aquatic organisms.

Tolerance Assessment

- The previously established tolerances for combined residues of
  trichlorfon and its cholinesterase-inhibiting metabolites are
  published in 40 CFR 561.190 and 40 CFR 180.198.  A summary of these
  tolerances are as follows:


                               Tolerances (ppm)
Commodity            United States     Canada     Mexico     Codex(g)

Alfalfa                 60.0             -         60.0          -
Alfalfa, hay            90.0             -         90.0          -
Artichokes               0 1(N)(b)      0.1(N)      0.1(N)      0.1
Apples                    -              -           -          2.0
Bananas                  2.0(c)         0.1(N)       -          0.2
Barley, forage          50.0             -           -           -
Barley. grain            0.1(N)          -           -           -
Barley, straw            1.0             -           -           -
Beans, dried             0.1(N)         0.1(N)      0.1(N)      0.1
Beans, lima             12.0(d)          -           -           -
Beans, lima vine hay    12.0             -           -           -
Beans, lima vines       12.0             -           -          0.1
Beans blackeyed
Beans snap               0.1(N)          -           -           -
Beans, vines             1.0             -           -           -
Beets                    0.1(N)         0.1(N)       -          0.2
Beets, sugar             0.1(N)          -           -           -
Beets, sugar tops       12.0             -           -           -
Birdsfoot trefoil, hay  90.0             -           -           -
Blueberries              0.1(N)         0.1(N)       -           -
Brussels sprouts         0.1(N)         0.1(N)       -          0.2
Cabbage                  0.1(N)         0.1(N)      0.1(N)      0.5
Carrots                  0.1(N)         0.1(N)       -           -
Cattle fat               0.1(N)          -          0.1(N)      0.1
Cattle, mbyp(e)          0.1(N)          -           -           -
Cattle, meat             0.1(N)         0.1(N)       -          0.1
Cattle, offal             -              -           -          0.1
Cauliflower              0.1(N)         0.1(N)       -          0.2
Celery                    -              -           -          0.2
Cereal grains             -             0.1(N)       -          0.1
Citrus fruit             0.1(N)          -          0.1(N)      0.1
Citrus (dry pulp)        2.5             -          2.5          -
Cherries                  -              -           -          0.1
Chili peppers             -              -          0.1(N)       -
Chickpeas                 -              -          0.1(N)       -
Clover                   60.0            -           -           -
Clover hay               90.0            -           -           -
Collards                  0.1(N)        0.1(N)       -           -
Corn, fodder             30.0            -           -           -
Corn, forage             30.0            -         30.0          -
Corn, fresh               0.1(N)(f)     0.1(N)      0.1(N)       -
Corn, grain               0.1(N)        0.1(N)      0.1(N)       -
Cottonseed                0.1(N)         -          0.1(N)      0.1
Cowpeas                   0.1(N)         -           -          0.1
Cowpeas, vines            1              -           -           -
Flax, straw               1.0            -           -           -
Flaxseed                  0.1(N)         -           -           -
Goats, fat                0.1(N)         -           -           -
Goats, mbyp               0.1(N)         -           -           -
Goats, meat               0.1(N)         -           -           -
Grapes                     -             -           -          0.5
Grass, pasture           60.0            -           -           -
Grass, pasture hay       90.0            -           -           -
Grass, range            240.0            -           -           -
Grass, range, hay       240.0            -           -           -
Horses, fat               0.1(N)         -           -           -
Horses, mbyp              0.1(N)         -           -           -
Horses, meat              0.1(N)         -           -           -
Kale                      0.1(N)        0.1(N)       -          0.2
Lettuce                   0.1(N)        0.1(N)      0.1(N)      0.5
Linseed                    -             -          -           0.1
Milk                      0.01(N)        -          -           0.05
Mustard greens             -             -          -           0.1
Oats, forage             50.0            -          -            -
Oats, grain               0.1(N)         -          -            -
Oats, straw               1.0            -          -            -
Peaches                    -             -          -          0.2
Peanuts                   0.05(N)        -         0.05        0.1
Peanuts, vine hay         4.0            -          -           -
Peanuts, vine hulls       4.0            -         4.0          -
Peppers                   0.1(N)        0.1(N)      -          1.0
Pigs, carcass meat         -             -          -          0.1
Pigs, edible offal         -             -          -          0.1
Pigs, fat                  -             -          -          0 1
Pumpkins                  0.1(N)         -          -          0.1
Radish                     -             -          -          0.1
Rapeseed                   -            0.1(N)      -          0.1
Rutabagas                  -            0.1(N)      -           -
Safflower seed            0.1(N)         -         0.1         0.1
Salsisfy                   -            0.1(N)      -           -
Sheep, fat                0.1(N)         -          -           -
Sheep, mbyp               0.1(N)         -          -           -
Sheep, meat               0.1(N)         -          -           -
Soya, beans                -             -          -          0 1
Squash                     -             -         0.1(N)       -
Spinach                    -            0.1(N)      -          0.5
Sugar beets                -            0.1(N)      -          0.05
Strawberries               -             -          -          1 0
Tomatoes                  0.1(N)        0.1(N)     0.1(N)      0.2
Turnips                    -            0.1(N)      -          0.1
Wheat, forage            50.0            -         50.0         -
Wheat, grain              0.1(N)         -          0.1(N)      -
Wheat, straw              1.0            -          1.0         -

(a) Tolerance is based on residues of trichlorfon and its
    cholinesterase-inhibiting metabolites.
(b) (N) is negligible residues.
(c) NMT 0.2 ppm will be present after peel is removed.
(d) Reflecting 0.1 ppm (N) in or on shelled beans.
(e) mbyp = meat by-products
(f) Including sweet K + CWHR.
(g) International Codex tolerances are expressed as MRLs or maximum
    residue limits.

- The data for trichlorfon residues in or on the following raw
  agricultural commodities are adequate to fill the residue data
  requirements:  beets, blueberries; peanut hulls and vine hay;
  birdsfoot trefoil hay (including chaff); corn grain; fresh corn;
  corn forage and fodder; forage of barley, oats, and wheat; bananas;
  peanuts; and the fat, meat, and meat by-products of goats, horses,
  and sheep.
- Sufficient residue data are not available to assess the adequacy of
  the trichlorfon tolerances for the following commodities (and their
  processed products, if applicable):  carrots, sugar beets and tops,
  lettuce, Brussels sprouts cabbage, cauliflower, collards, cowpeas,
  dried beans, lima beans, snap beans, bean vines, lima bean vines and
  hay, peppers, tomatoes, pumpkins, citrus fruits and dried citrus
  pulp, barley grain and straw, oat grain and straw, wheat grain and
  straw, pasture and rangeland grass forage and hay, alfalfa forage
  and hay, clover forage and hay, artichokes, cottonseed, flax seed
  and straw, safflower seed, cattle (fat, meat and meat by-products),
  and milk.  Residue data are required for processed products of the
  following commodities to determine the necessity of food/feed
  additive tolerances:  citrus fruits, cottonseed, wheat grain, sugar
  beets, and tomatoes.  Residue data for tobacco are required to
  determine the human hazard associated with this trichlorfon use.
  Poultry residue studies are required to determine the necessity of
  trichlorfon tolerances for poultry fat, meat, and meat by-products,
  a tolerance for eggs is not required.  No group crop tolerances are
  appropriate at the present time.
- Residue data and tolerance proposals must be submitted for the
  following raw agricultural commodities for which tolerances are not
  currently established, but for which intrastate registrations exist:
  strawberries, watermelon, broccoli, kale, spinach, garlic, onions,
  radishes, rutabagas, celery, and turnips.
- No new crop groupings can be established at this time because of
  extensive residue chemistry data gaps.  Compatibility between Codex
  MRLs and U.S. tolerances will be assessed when data gaps specified
  in Table A have been submitted and evaluated.
- The lack of adequate animal and plant metabolism studies precludes a
  determination of the trichlorfon residues of concern in plants and
  animals.  Prior to submission of additional residue data, it is
  imperative that the residues of concern be determined.
- The previously established ADI for trichlorfon is 0.1250 mg/kg/day
  and the TMRC, based on the established tolerances for residues of
  trichlorfon as cited under 40 CFR 180.198, is 0.0627 mg/day assuming
  a 1.5 kg diet; the TMRC currently accounts for only 0.84% of the ADI.
  No adequate study currently supports the previously established ADI. A
  new ADI will be established when the chronic toxicity data require-
  ments are satisfied.

Summary Science Statement

   Numerous toxicology, environmental fate, product chemistry and 
residue chemistry data gaps preclude the Agency from making a complete 
assessment for trichlorfon. Refer to the Science Findings Section for 
the available data.


- Use classification: not classified
- Use restrictions: 24-hour reentry interval
- Unique warning statement required on labels: Labels for all
  manufacturing-use products (MPs) containing trichlorfon must bear
  statements reflecting the hazards to man and the environment [40 CFR
  162.10]. Trichlorfon is in Toxicity Category II on the basis of acute
  oral effects and Category III on the basis of acute dermal effects.
  The Agency has no valid acute inhalation, primary eye, primary dermal,
  or dermal sensitization data for trichlorfon manufacturing-use
  - Based on the data reviewed by the Agency, the environmental hazard
    statement below is required to appear on all MPs containing
    - This pesticide is toxic to fish and wildlife and is extremely
      toxic to aquatic invertebrates. Do not discharge into lakes,
      streams, ponds, or public water unless in accordance with an NPDES
      permit. For guidance, contact your Regional Office of the
      Environmental Protection Agency.
- Labels for all end-use products (EPs) containing trichlorfon must
  bear a statement reflecting the hazard to man and the environment
  [40 CFR 162 10]
  - Based on data reviewed by the Agency, the following environmental
    hazards statements are required to appear on the EP products:
    - All trichlorfon products intended for outdoor use must bear the
      following statement:
    - This pesticide is toxic to fish and wildlife and is extremely
      toxic to aquatic invertebrates.
  - Additional precautionary statements are required as indicated below:
    - Trichlorfon products intended for direct applications to ponds:
      - Consult your State Fish and Game Agency before applying this
        product to public waters. Permits may be required before
        treating such waters.
    - Trichlorfon products intended for use in forestry:
      - Do not apply directly to water or wetlands not under forest
        canopy. Runoff and drift from treated areas may be hazardous to
        aquatic organisms in neighboring areas.
    - Trichlorfon products intended for outdoor use other than direct
      applications to ponds or forestry:
      - Do not apply to water or wetlands.  Runoff from treated areas
        may be hazardous to aquatic organisms in neighboring areas.
- The Agency is currently considering various approaches to address the
  endangered species concerning this and other chemicals.  The
  registration standard may be amended to incorporate the results of
  this additional review.
  - To avoid the possible misuse of trichlorfon in eating establishments
    the following statement is required for all EPs used in eating
  - This product shall not be used in rooms or areas where food is
    either consumed or prepared.
  - Bee precautionary language per PR Notice 68-19 is no longer
    required, since the data indicates that trichlorfon has a low
    toxicity to bees.
  - The reentry statement below must appear on all trichlorfon labels
    with directions for use on crops:
  - Do not reenter treated fields within 24 hours, unless protective
    clothing is worn.
  - Refer to PR Notice 83-2 for additional information on reentry and
    worker protection labeling requirements.

Summary of risk/benefit review:

- Dichlorvos (DDVP). a putative metabolite of trichlorfon, was
  originally referred and accepted for the Rebuttable Presumption
  Against Registration (RPAR) process because scientific studies
  indicated that dichlorvos was mutagenic as well as potentially
  carcinogenic, neurotoxic and teratogenic in laboratory animals.  The
  RPAR Decision Document on Dichlorvos was issued by the Agency on
  September 30, 1982.  In this document (i.e., Decision Document on
  Dichlorvos, Office of Pesticides and Toxic Substances, U.S. EPA,
  Washington, DC. September 30, 1982) the Agency evaluated the
  available data on dichlorvos in accordance with 40 CFR 162.11
  (Criteria for Determination of Unreasonable Adverse Effects) and
  concluded that the existing evidence did not support the issuance of
  an RPAR for dichlorvos, and consequently that an RPAR for
  trichlorfon as a precursor of dichlorvos was also not warranted.
- The DDVP Decision Document concluded that additional data on
  carcinogenicity and mutagenicity were needed to complete the risk
  assessment for dichlorvos.  DDVP was removed from the RPAR process
  and returned to the registration process.  On March 23, 1983 the
  Agency issued a Data Call-In Notice under FIFRA Section 3(c)(2)(b)
  requesting data on potential mutagenic effects of dichlorvos be
  submitted by March 23, 1985.  However, the Agency will wait until
  the continuing National Cancer Institute (NCI) dichlorovos bioassay
  on carcinogenicity is completed (currently scheduled for completion
  in 1984) and evaluated, prior to determining if additional data on
  the carcinogenicity of dichlorvos will be required.  Since
  dichlorvos can be metabolized from trichlorfon, evaluation of these
  studies will be necessary for the completion of the trichlorfon risk
- Trichlorfon was originally referred and entered to the Rebuttable
  Presumption Against Registration (RPAR) process because scientific
  studies suggested that trichlorfon may be oncogenic, teratogenic,
  fetotoxic and mutagenic.  In the Trichlorfon Registration Standard
  (June 1984) document the Agency has evaluated the available data on
  trichlorfon in accordance with 40 CFR 162.11 (Criteria for Deter-
  mination of Unreasonable Adverse Effects) and concluded that the
  existing evidence does not support the issuance of an RPAR for
  trichlorfon because the existing data base is incomplete.  Additional
  data are required to complete the risk assessment for trichlorfon.
  Oncogenicity, chronic feeding, teratogenic, mutagenicity, inhalation,
  dermal, eye irritation, neurotoxicity, and metabolism studies are

              5.  SUMMARY OF MAJOR DATA GAPS

- Product Chemistry:  Data on product identity analysis and
  certification of product ingredient and physical and chemical
  characteristics are the major product chemistry gaps.
- Residue Chemistry:  Additional data are required to support the
  tolerances for a variety of crops.  Data from animal and plant
  metabolism studies are also required.  Residue chemistry data
  requirements are outlined in detail in the tolerance assessment in
  Section 3 of this Fact Sheet.
- Toxicology:  The following studies are required:  acute inhalation
  toxicity, primary eye irritation, primary dermal irritation, dermal
  sensitization, 90-day feeding, 21-day dermal, 90-day dermal, 90-day
  inhalation, 90-day neurotoxicity, chronic toxicity, oncogenicity,
  teratogenicity, chromosomal aberration, general metabolism, and
  domestic animal safety.
- Wildlife and aquatic organisms:  The following studies are required:
  fish early life stage and aquatic invertebrates life cycle.
- Environmental Fate:  The following studies are required:  hydrolysis; 
  photodegradation in water, soil and air; metabolism studies (lab) in 
  aerobic soil, anaerobic soil, anaerobic aquatic and aerobic aquatic 
  environments; mobility studies including leaching and adsorption/
  desorption and volatility (lab); dissipation studies (field) in soil,
  aquatic (sediment) and forestry; accumulation studies in fish, in
  aquatic non-target organisms, and rotational crops (confined).

NOTE:  All data must be submitted by June 1987.

                  6. CONTACT PERSON AT EPA

William H. Miller
Product Manager (16)
Insecticide-Rodenticide Branch
Registration Division (TS-767)
Environmental Protection Agency
Washington, DC  20460
(703) 557-2600