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tetrachlorvinphos (Rabon, Gardona) EPA Pesticide Fact Sheet 10/88

EPA Pesticide Fact Sheet


Name of Chemical:  Tetrachlorvinphos
Reason for Issuance:  Registration Standard
Dale Issued:  October 14, 1988
Fact Sheet Number:  184


                      1. DESCRIPTION OF CHEMICAL

- Generic Name: (Z)-2-chloro-1-(2,4,5-trichlorophenyl) vinyl dimethyl
  phosphate
- Common Name:  Tetrachlorvinphos
- Trade and Other Names:  Rabon, Stirofos, Gardona, Gardcide
- EPA Chemical (Shaughnessy) Codes:  083701
- Chemical Abstracts Service (CAS) Number: 22248-79-9  [(Z)-isomer];
  22350-76-1  [(E)-isomer]; 961-11-5 (mixed isomers)
- Year of Initial Registration:  1966
- Pesticide Type:  Insecticide
- Chemical Family:  Organophosphate
- U.S. and Foreign Producers: E.I. Dupont de Nemours & Co.; Fermenta
  Animal Health Co.

                      2. USE PATTERNS AND FORMULATIONS

- Application:  Control of filth or manure flies associated with 
  livestock and poultry as a feed additive, in mineral blocks;
  indoor on animal premises, direct animal treatment, garbage dumps.
- Types and Methods of Application:  Premise treatment by conventional
  hydraulic sprayer or low pressure knapsack; animal treatment by hand
  (shaker can, hand duster, grooming brush, dust mitt), pressurized
  spray, flea collars, ear tags, oral feed additive, dust bags, and oral
  mineral block
- Types of Formulations:  Dust, granular, pelleted/tableted, wettable
  powder, wettable powder/dust, impregnated material, emulsifiable
  concentrate, ready-to-use and pressurized liquid.


                            3. SCIENCE FINDINGS


Summary Science Statement

   Technical tetrachlorvinphos is not very toxic by the inhalation route 
of exposure, and does not produce clinical signs of neurotoxicity.  No 
data are available to assess the toxicity of tetrachlorvinphos by the 
acute oral and dermal routes of exposure and studies are being required 
in the Standard.  Tetrachlorvinphos is not teratogenic in rabbits but 
the effects in rats have not yet been assessed.  Rat teratology data 
received in response to a Comprehensive Data Call-In (1984) were not 
received in time to be included in the reviews for this Standard.  
Available data indicate that the potential effects of tetrachlorvinphos 
on reproduction are minimal; the only compound-related effect observed 
in the rat was an increase in liver size in the F3b weanlings in the 
highest dose tested (HDT).  There are no acceptable mutagenicity studies 
on tetrachlorvinphos.  Based on a chronic feeding study in dogs, 
cholinesterase inhibition and reduced weight gain are the significant 
toxic effects resulting from chronic exposure to tetrachlorvinphos.

   Based on the Agency's Guidelines for Carcinogen Risk Assessment, the 
Agency has classified tetrachlorvinphos as a Group C (possible human) 
carcinogen with a cancer potency estimate (Q1*) of 3.14 x 10-3 
(mg/kg/day)-1.

   Available data indicate that tetrachlorvinphos is practically non-
toxic to birds, but is highly toxic to fish and honey bees (contact).  
Available data are insufficient to characterize the environmental fate 
of tetrachlorvinphos.  Preliminary findings indicate that 14C 
tetrachlorvinphos degrades with a half-life of <8 days in medium loam 
soil.



Chemical Characteristics of the Technical Material

- Physical State:  solid
- Color:  tan to brown
- Odor:  mild chemical
- Molecular Weight and Formula:  366.0; C10H9Cl4O4P
- Boiling Point:  N/A solid at room temperature
- Vapor Pressure:  no data submitted
- Density:  (bulk density) 50-55 lb/cu ft
- Solubility in various solvents:  at 0 degrees C:
                                        40 ppm in chloroform,
                                        40 ppm in dichloromethane,
                                        20 ppm in acetone,
                                         8 ppm in xylene,
                                        15 ppm in water at 24 C


Toxicology Characteristics

- Acute Oral:  No available studies
- Acute Dermal:  No available studies
- Primary Dermal Irritation:  No available studies
- Primary Eye Irritation:  No available studies
- Dermal Sensitization:  No available studies
- Acute Inhalation:  3.61 m/L      Tox. category III
- Major routes of exposure:  dermal and inhalation
- Delayed neurotoxicity:  negative
- Subchronic toxicity:  normocytic anemia and plasma cholinesterase 
  inhibition
- Oncogenicity:  Group C carcinogen; (mouse) Sys.. NOEL = 240 mg/kg/day
                                      (rat)  Sys.  NOEL = 6.25 mg/kg/day
- Chronic Feeding:  (Dog) Sys. NOEL = 3.13 mg/kg/day
                          Sys. LEL =  50 mg/kg/day
- Metabolism:  (dog and rat) completely metabolized in both; primarily
  excreted in urine
- Teratogenicity:  (Rabbits) Maternal NOEL = 375 mg/kg
                             Fetotoxic NOEL = 150 mg/kg
                             Teratogenic NOEL = >750 mg/kg
- Reproduction:  (Rat) NOEL = 16.65 mg/kg/day
                       LEL =  50.0 mg/kg/day
- Mutagenicity:  No acceptable studies


Physiological and Biochemical Characteristics

- Mechanism of Pesticidal Action:  Cholinesterase inhibition following
  ingestion of tetrachlorvinphos
- Metabolism and Persistence in Plants and Animals:  Currently, there
  are no end-use products registered for use on any plant commodity.
  The nature of the residue in animals is not adequately understood.
  However, the available animal metabolism data indicate that residues
  of tetrachlorvinphos will occur in the tissues of ruminants and 
poultry
  following ingestion of feeds containing tetrachlorvinphos.


Environmental Characteristics

   Available data are insufficient to characterize the environmental 
fate of tetrachlorvinphos.


Ecological Characteristics

- Avian acute toxicity:  Mallard Duck LD50 > 2,000 mg/kg
- Avian dietary toxicity:  Mallard Duck LD50 > 5,OOO mg/kg
- Freshwater fish acute toxicity:  Bluegill LC50 = 0.53 ppm
                                   Rainbow Trout LC50 = 0.43 pm
- Freshwater invertebrate toxicity:  No available studies
- Marine invertebrate toxicity:  No available studies


                   4. TOLERANCE ASSESSMENT

   Tolerances have been established for residues of tetrachlorvinphos 
in/on a variety of raw agricultural commodities (40 CFR 180.252).  A 
feed additive regulation has also been established for tetrachlorvinphos 
(21 CFR 186.950).  Since there are no currently registered products 
bearing labeling for use on food crops tolerance revocation procedures 
(40CFR 180.7) will be initiated for apples, field corn, sweet corn and 
popcorn, fresh corn forage and fodder, alfalfa, cherries, cranberries, 
peaches, pears, and tomatoes.  The Agency has evaluated the residue and 
toxicology data supporting the tolerances on animal commodities and has 
determined that it does not have sufficient data to support the 
currently established tolerances residues of tetrachlorvinphos.  Because 
of the extensive residue chemistry and toxicology data gaps, no 
significant new tolerances or new food uses will be granted until the 
Agency has received data sufficient to evaluate the dietary exposure of 
tetrachlorvinphos.

   There are no Canadian or Mexican tolerances and no Codex Maximum 
Residue Limits (MRLs) have been established for tetrachlorvinphos 
residue in poultry fat and eggs.  Therefore, no compatibility questions 
exist with respect to the Codex MRLs.


                 5  SUMMARY OF REGULATORY POSITIONS

   The Agency is not initiating a special review for tetrachlorvinphos 
at this time.  Although tetrachlorvinphos has been classified as a Group 
C oncogen (possible human), anticipated dietary exposure to humans and 
the associated risk is not high (10-6).

     The Agency has determined that based upon currently available data,
tetrachlorvinphos does not meet the risk criteria (40 CFR 152.170) for
restricted use, and thus, products containing tetrachlorvinphos do not
warrant restricted use classification at this time.

   The Agency will reevaluate the safety and efficacy data for various
formulations of tetrachlorvinphos to domestic animals (dogs, cats, 
horses) in order to determine if further regulatory action is warranted.

   The Agency is requiring protective clothing for workers or other 
users who mix, load, and/or apply tetrachlorvinphos.

   The Agency is requiring data to show the concentration and 
degradation products of tetrachlorvinphos in fresh manure at the time it 
is used on land as fertilizer.

   The Agency will not grant any tolerances for significant new food 
uses until sufficient data (residue chemistry and toxicology) are 
submitted for the Agency to perform a tolerance reassessment for 
tetrachlorvinphos.


                    6. LABELING REQUIREMENTS

   All products allowing for outdoor use must bear the following 
environmental hazards statement:

     "This is toxic to fish.  Do not contaminate water when disposing
      of equipment washwaters"

   The following protective clothing statements must appear on all 
products allowing for use on livestock, agricultural premises, feed 
additives:  For sprays and dusts:

     "Wear long-sleeved shirt and pants; chemical resistant gloves,
      shoes and socks."  For ear tags:  "Wear gloves when applying
      tags"

   The following statements must appear on all products allowed for 
domestic use:

     "Wear long-sleeved shirt and pants, shoes and socks."

   All products allowing for use as a feed additive and/or use of manure
(droppings) must bear the following statement:

     "Do not use manure//droppings on land where food crops are to be
      grown during the current growing season."



                      7. SUMMARY OF CURRENT DATA GAPS

                                                    DUE DATE FROM DATE
        DATA                                           OF STANDARD
        ____                                       ___________________


Product Chemistry - All                              9-15 Months

Environmental Fate - Hydrolysis
                     Photodegradation (in water)
                     Metabolism Studies
                     Mobility Studies                9-27 Months
                     Dissipation Studies (soil)
                     Dissipation Study (excrement)
Toxicology - Acute Oral (rat)
                   Acute Dermal (rat)
                   Eye Irritation (rabbit)           9-12 Months
                   Dermal Irritation (rabbit)
                   Dermal Sensitization (guinea pig)
                   Mutagenicity
                   21-Day Dermal
                   Oncogenicity (rat)                50 Months
                   Teratology (rat)
Ecological Effects - Acute Toxicity to               9 Months
                     Freshwater Invertebrates
Residue Chemistry - Livestock Metabolism
                    Analytical Methods
                    Storage Stability                18-24 Months
                    Magnitude of residues
                    in meat, milk, eggs


                     8. CONTACT PERSON AT EPA

George T. LaRocca
Product Manager (15)
Insecticide-Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, S. W.
Washington, D.C.  20460

Office location and telephone number:  Room 204; (703) 557-2400

Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA  22202
(703) 557-2600


DISCLAIMER:  The information in this Pesticide Fact Sheet is a summary 
only and is not to be used to satisfy data requirements for pesticide 
registration and reregistration.  The complete Registration Standard for 
the pesticide may be obtained from the National Technical Information 
Service.Contact the Product Manager listed above for further 
information.