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ethoprop (Mocap) Chemical Fact Sheet 6/83

                        CHEMICAL FACT SHEET FOR:


DATE ISSUED:  JUNE, 1983                 DATE UPDATED:  FEBRUARY, 1985

                    1.  DESCRIPTION OF CHEMICAL

- Generic Name:  O-ethyl S.S-dipropyl phosphorodithioate
- Common Name:  ethoprop
- Trade Name:  Mocap
- EPA Shaughnessy Code:  041101
- Chemical Abstracts Service (CAS) Number:  13194-84-4
- Year of Initial Registration:  1967
- Pesticide Type:  soil insecticide-nematicide
- Chemical Family:  organophosphate
- U.S. and Foreign Producers:  Rhone-Poulenc, Inc.


- Application sites:  registered for use on a variety of tropical
  fruits, vegetables, ornamentals, field crops, commercial turf, and
  home lawns.
- Types of formulations:  granulars, emulsifiable concentrates
- Types and methods of application:  applied as a soil incorporated,
  broadcast, or band treatment, as a root dip treatment for citrus and
  certain ornamentals.  Ethoprop formulations are commonly applied by
  using ground equipment and are incorporated into the soil immediately
  after application with the use of cultivating equipment and/or by
  irrigation.  Also, spray equipment (i.e., backpack sprayers) and
  watering cans may be used for application.
- Application rates:  vary according to formulation and crop
- Usual carriers:  Confidential Business Information

                      3.  SCIENCE FINDINGS

Chemical Characteristics

- Ethoprop is a clear yellow-tinted liquid with a strong mercaptan odor.
  The empirical formula is C8H1902PS2, and the molecular weight is
  242.307.  The boiling point is 86-91 degrees C at 0.2 mmHg.  Ethoprop
   is soluble in water to 750 ppm and soluble in most organic solvents.

Toxicological Characteristics

- Currently available toxicology studies on ethoprop are as follows:
  - Oral LD50 in rats:  56.2 mg/kg for males and 30.2 mg/kg for
  - Dermal LD50 in rabbits:  23.7 ul/kg
  - Primary dermal irritation:  Unknown since death prevented
    manifestation of a skin irritation response.
  - Primary eye irritation:  Unknown since all rabbits died within 1
    hr. of administration.  Substance is too toxic to determine an
    eye irritation potential.
  - Inhalation LC50:  0.123 mg/liter
  - Acute delayed neurotoxicity:  Hens treated with ethoprop were not
    shown to produce signs of delayed neurotoxicity.
  - Teratology in rats:  Maternal NOEL = 1.6 mg/kg; terata NOEL = 1.6
  - 90-day dog feeding study:  Systemic NOEL = 100 ppm at the highest
    dose tested; Cholinesterase NOEL = 1 ppm.
- Adequate studies are available to assess the acute toxicological
  effects of technical ethoprop.  No toxicological hazards of concern
  have been identified in the studies reviewed for the Standard.

Physiological and Biochemical Behavioral Characteristics

- Metabolism and persistence in plants and animals:  Ethoprop in bean
  and corn plants is metabolized by hydrolysis following uptake from
  the soil.  The metabolites identified are ethyl propyl sulfide,
  propyl disulfide, ethyl propyl sulfoxide, and water soluble high-
  boiling phosphoric acids and/or their salts.  The only residue of
  toxicological concern is the parent compound.
- There are no data to indicate how ethoprop is metabolized or
  excreted by animals.  In one feeding study in which dogs were fed
  unlabeled ethoprop for 21 days at rates up to 2.3 ppm of their diet,
  no detectable residues (i.e. >0.01 ppm) were found in their tissues.
  Because feed items with established negligible residue tolerances
  (<0.02 ppm) are expected to have little, if any, ethoprop residues,
  it is concluded that the metabolism in animals, although not
  completely known, is at this time sufficiently detailed.

Environmental Characteristics

- Ethoprop is not expected to contaminate drinking water supplies. It
  degrades fairly rapidly with half-lives of 3-56 days in soil.
  Increase in soil temperature tends to increase the dissipation rate.
  However, ethoprop is very mobile in sandy soil and has a potential
  for contaminating groundwater in areas of sandy soil with a high
  water table.  Because of this, soil dissipation study monitoring may,
  depending on the leaching data, have to be conducted at a depth
  greater than 6 inches.

Ecological Characteristics

- Based on studies available to assess hazards to wildlife and aquatic
  organisms, ethoprop is characterized as very highly toxic to birds,
  marine/estuarine crustaceans, and marine/estuarine fish species.  It
  is moderately to highly toxic to coldwater fish species and
  moderately toxic to honeybees.
- Results of currently available studies are as follows:
  - Avian oral LD50:  ranges from 4.21 - 61 mg/kg
  - Avian dietary LC50:  ranges from 33 - 118 ppm in upland gamebirds
    and 287 - 550 ppm in waterfowl
  - Fish LC50:  ranges from 1.02 mg/l - 1.85 mg/l in rainbow trout
  - Aquatic invertebrate LC50:  ranges from 13 ug/l - 25.3 ug/l

Tolerance Assessment

- Tolerances are established for negligible residues of the insecticide/
  nematicide ethoprop in or on the following raw agricultural
  commodities:  bananas, cabbage, corn-grain, corn fodder and forage,
  cucumbers, fresh corn including sweet corn (kernels plus cob with
  husk removed), lima beans, lima bean forage, peanuts, peanut hay,
  pineapples, pineapple fodder and forage, soybeans, soybean forage
  and hay, sugarcane, sugarcane fodder and forage, and sweet potatoes
  at 0.02 parts per million.  These tolerances are published in 40
  CFR 180.262.  There are no international tolerances nor Codex
  Maximum Residue Limits (MRLs) for residues of ethoprop.
- Tolerances for most raw agricultural commodities (with the
  exception of potatoes and tobacco) are supported by currently
  available residue data.  However, the Agency is unable to complete
  a tolerance reassessment because of residue chemistry and
  toxicology data gaps.
- A provisional acceptable daily intake (PADI) is calculated to be
  0 000075 mg/kg/day, the provisional maximum permissible daily
  intake (PMDI) is 0.0045 mg/day, and the theoretical maximum residue
  concentration (TMRC) is 0.0052 mg/day for a 1.5 kg diet.  The
  percent of the PADI utilized is 115.02%.  Although the PADI has been
  exceeded, it is concluded that exceeding the PADI does not
  necessarily in and of itself represent an immediate hazard to the
  public.  The actual levels of residues to which the public is
  exposed are likely to be considerably less than this theoretical
  maximum would indicate for some of the following reasons:
  - Not every crop for which a tolerance has been established has
    been treated with the pesticide.
  - Most treated crops have residue levels which are below the
    established tolerance level.
  - Processing or time to market often result in further residue
  - Preparing food for consumption often results in residue reductions.
  - Not all crops contributing to the TMRC (PADI) are likely to be
    consumed by an individual.
  - Market basket surveys conducted by FDA indicate that little if
    any real pesticide residues of organophosphates actually remain
    in/on finished foods.
- After review of the requested toxicology data, the ADI will be

- Summary Science Statement

- Adequate studies are available to assess the acute toxicological
  hazards of technical ethoprop.  No toxicological hazards of concern
  were identified.  Available studies indicate that ethoprop is very
  toxic to birds, marine/estuarine crustaceans, and fish species.
  It is moderately toxic to coldwater fish species and moderately
  toxic to honeybees.
- Although a full tolerance and risk assessment cannot be completed
  due to a number of data gaps, there is no evidence to suggest that
  current tolerances are likely to expose the public to unreasonable
  adverse effects.


- Use classification:  The Restricted Use classification for all
  ethoprop emulsifiable concentrate formulations containing 40% and
  greater will continue.  Granular end-use products containing 10% or
  more ethoprop with disulfoton 5% and greater are classified for
  Restricted Use.  All other granular and/or fertilizer end-use
  products containing ethoprop are also classified Restricted Use;
  however, registrants of these products have the option of accepting
  the restricted use classification, or submitting data to show that
  the product does not warrant this restriction.  All such products
  released for shipment on September 1, 1985, or thereafter, must be
  labeled for restricted use.  Similarly, all such products which are
  in channels of trade on or after September 1, 1986, must bear
  restricted use labeling.
- Although the Agency is unable to complete a tolerance reassessment
  because of certain residue chemistry and toxicology data gaps, the
  Agency concludes that no changes in present tolerances are indicated
  at this time.  Further, although the provisional acceptable daily
  intake has been exceeded, future requests for tolerances will not
  be automatically rejected on this basis.
- No federal or state reentry intervals have been established for
  ethoprop.  There is no need to establish any reentry intervals,
  since the practice of soil incorporation is expected to minimize
  exposure during reentry operations.  This is also true for turf areas
  where the pesticide is watered in.
- The Agency has identified a potential avian adverse effect concern.
  Based on acceptable subacute dietary studies, it is calculated that
  the expected residues on avian foodstuffs following a single
  application of ethoprop at a rate of 6 pounds a.i. per acre (maximum
  registered corn rate) exceed the subacute dietary LC50 level in
  avian species.  In order to determine whether significant evidence
  relating to this adverse effect would raise prudent concerns of
  unreasonable adverse risk to man or the environment, the Agency is
  requiring additional avian field testing data.
- Unique warning statements:  The following additional human hazard
  statement must appear on all manufacturing-use product labels:
  - Poisonous if absorbed through the eye.  Do not get in eyes.
- Although a full tolerance reassessment and risk assessment cannot be
  completed, there is no evidence to suggest that current tolerances
  are likely to expose the public to unreasonable adverse effects.

                   5.  SUMMARY OF MAJOR DATA GAPS

- 90-day feeding:  rodent, non-rodent
- 21-day dermal
- chronic toxicity:  2 species
- oncogenicity study:  2 species
- teratogenicity:  1 specie
- reproduction:  2 species
- mutagenicity testing:  gene mutation, chromosomal aberration, other
  mechanisms of mutagenicity
- general metabolism
- hydrolysis study
- photodegradation study:  in water
- aerobic and anaerobic soil study
- leaching and adsorption/desorption study
- field soil dissipation study
- accumulation studies:  rotational crops and fish
- data on residues in potatoes and tobacco
- 2 acute field studies
- freshwater fish LC50
- acute LC50 freshwater invertebrates
NOTE:  All studies are to be submitted to the Agency by June, 1986.

                    6.  CONTACT PERSON AT EPA

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