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carbophenothion (Trithion) Chemical Fact Sheet 5/84

                           CHEMICAL FACT SHEET FOR:




                       1.  DESCRIPTION OF CHEMICAL

Chemical Name:  s-[[(p-chlorophenyl)thio]methyl]O,O-diethyl
Common Name:  carbophenothion
Trade Name:  Trithion
EPA Shaughnessy Code:  058102
Chemical Abstracts Service (CAS) Number:  786-19-6
Pesticide Type:  Insecticide and Acaricide
Chemical Family:  Organophosphate
U,S. and Foreign Producers:  Stauffer Chemical Co.

                    2. USE PATTERNS AND FORMULATIONS

- Registered for use on a wide variety of vegetable, fruit, nut, forage,
  ornamental, and forestry sites.
- Majority of pesticide use is on citrus.
- Commercially available as dust, granular, pelleted, wettable powder,
  and emulsifiable concentrate formulations.
- Applied as foliar applications using either ground or aerial
  equipment. Dormant and delayed dormant applications are made to some
  fruit and nut trees. There are also limited uses as a seed treatment,
  dip, and soil insecticide.
- See also EPA Index Entry for carbophenothion.

                        3.  SCIENCE FINDINGS

Chemical Characteristics

- Physical state:  Liquid 
- Odor:  Mild mercaptan 
- Color:  Yellow-brown 
- Empirical formula:  C11H16C102P53 
- Molecular weight:  342.9 
- Vapor pressure:  0.008 u at 25 degrees C 
- Solubility in water:  0.34 ppm at 20 degrees C 
- Specific gravity:  1.274 at 20 degrees C 
- pH:  2.43 
- Boiling point:  82 degrees C at 0.01 mm Hg 
- Miscibility:  miscible with most organic solvents such as petroleum
  ether, benzene, toluene, xylene, ethers, alcohol, and ketones.

Toxicological Characteristics

- Acute Oral Toxicity:  0.02 ml/kg in male rats
- Reproduction:  A rat 3-year generation study had a NOEL of 10 ppm
- Acute Delayed Neurotoxicity:  not neurotoxic at 330 mg/kg 
- 2-Year Dog Feeding Study:  NOEL of 5 ppm - Adequate studies are
  unavailable to assess the acute toxicological effects of
  carbophenothion. Preliminary data indicate that carbophenothion is in
  Toxicity Category I on the basis of acute oral effects.
  Carbophenothion is a cholinesterase inhibitor. It is not adequately
  tested for acute toxicology, chronic toxicity, oncogenicity, or

Environmental Characteristics

     Available data are insufficient to assess the environmental fate of 
carbophenothion or to assess the potential exposure of humans and non-
target organisms to carbophenothion. Preliminary data indicate that 
carbophenothion is relatively immobile in sandy loam soils. However, the 
Agency cannot more completely assess the potential for carbophenothion 
to contaminate groundwater until data are submitted. Preliminary data 
indicate that there may be a potential for carbophenothion to accumulate 
in spot and juvenile sheepshead minnows.

Ecological Characteristics

- Freshwater Fish Acute Toxicity:  Coldwater fish, rainbow trout - 
  56 ppb; Warmwater fish, bluegill sunfish - 13 ppb. 
- Avian Acute Oral Toxicity:  Bobwhite quail - 320 mg/kg. 
- Acute Toxicity to Freshwater Invertebrates:  adult Palaemonetes 
  1.2 ppb 
- Acute Toxicity to Marine and Estuarine Organisms:  pink shrimp 
  0.47 ppb, sheepshead minnow - 17 ppb. 
- Chronic Toxicity for Marine and Estuarine Organisms:  grass shrimp
  life cycle study - Maximum Acceptable Theoretical Concentration (MATC)
  - >0.22<0.36 ppb; sheepshead minnow embryo/juvenile study MATC
  >1.3<2.8 ppb. 
- Carbophenothion is characterized as very highly toxic to freshwater
  and marine/estuarine organisms and highly toxic to upland gamebirds.
  See discussion under Section 4 (Summary of Regulatory Position and

Tolerance Reassessment

- Tolerances for combined residues of the insecticide carbophenothion
  (S-[p-chlorophenylthio)methyl] O,O-diethyl phosphorodithioate) and its
  cholinesterase-inhibiting metabolites in or on raw agricultural
  commodities are established as follows:
  - 10 parts per million in or on almond hulls.
  - 5 parts per million in or on alfalfa (fresh), alfalfa (hay), bean
    straw, clover (fresh), clover (hay), corn forage, sorghum forage,
    sugarbeets (roots), sugarbeets (tops).
  - 4 parts per million in or on blueberries.
  - 2 parts per million in or on grapefruit, lemons, limes, oranges,
    sorghum grain, tangerines.
  - 0.8 part per million in or on apples; apricots; beans, snap
    (succulent form); beans, lima (succulent form); beets, garden
    (roots); beets, garden (tops); cantaloupes; cherries; crabapples;
    cucumbers; eggplants; figs; grapes; nectarines; olives; onions (dry
    bulb); onions (green); peaches; pears; peas (succulent form);
    peppers; pimentos; plums (fresh prunes); quinces, soybeans
    (succulent form); spinach; strawberries; summer squash; tomatoes;
  - 0.2 part per million in or on corn (kernels plus cob with husks
    removed), undelinted cottonseed.
  - 0.1 part per million in the fat of meat of cattle, goats, hogs and
  - 0.1 part per million (negligible residue) in or on beans (dry),
    pecans, and walnuts.
  - Zero in milk.
- The tolerances are published in 40 CFR 180.156. Tolerances for
  numerous raw agricultural commodities as well as processed products
  are not supported by available data. 
- No new crop groupings can be established at this time because of
  extensive residue chemistry data gaps. Compatibility between Codex
  MRL's and U.S. tolerances will be assessed when data gaps specified in
  Table A have been submitted and evaluated. 
- The Acceptable Daily Intake (ADI) for carbophenothion is 0.0125
  mg/kg/day. This is based on an acceptable dog chronic feeding study
  with a No Observable Effect Level (NOEL) of 5.0 ppm and a safety
  factor of 10. 
- The Theoretical Maximum Residue Contribution (TMRC), based on relevant
  food factors and the tolerances cited in 21 CFR 193.50 and 40 CFR
  180.156, is 0.5806 mg/day assuming a 1.5 kg diet. Accordingly, the
  percentage of the ADI used up is 77.42%.


     The Agency has identified concerns over the potential adverse 
effects of carbophenothion to aquatic and terrestrial species. Based on 
acceptable aquatic acute toxicity studies, it is calculated that the 
expected concentration of carbophenothion following direct application 
to a 6-inch layer of water exceed one half the acute toxicity level in 
aquatic species. Based on a scientifically sound subacute dietary study, 
it is calculated that the expected residues in avian foodstuffs 
following a single application of carbophenothion at a rate of 1 pound 
a.i. per acre exceed one fifth the subacute dietary toxicity in avian 
species. In addition, although there is insufficient information on the 
granular formulations, the Agency expects that granular applications of 
carbophenothion would have an adverse impact on birds.

     A total risk assessment cannot be made until gaps in the data base 
for terrestrial species and environmental fate are filled.

     The Agency is unable to complete a full tolerance reassessment of 
carbophenothion because of extensive residue chemistry and toxicology 
data gaps. Future requests for tolerances will not be automatically 
rejected, but will be considered on a case-by-case basis.

     California has established reentry intervals for carbophenothion of 
14 days for citrus, peaches, nectarines, and grapes; and 2 days for all 
the other crops. A federal reentry interval of two days for 
carbophenothion has been established for all crops under 40 CFR 170. The 
Agency is now requiring two days for all crop uses of carbophenothion on 
an interim basis, and is requesting data for establishing permanent 
reentry interval(s). The Agency is also requiring an interim 24-hour 
reentry interval for the domestic outdoor usage on home lawns and 
ornamentals, and requesting data to enable the Agency to make a risk 

     The Agency has determined that all products warrant restricted-use 
classification based on acute dermal toxicity. Registrants have the 
option of placing the restricted-use classification on the labeling, or 
submitting acute toxicity data to the Agency.

                  5.  SUMMARY OF MAJOR DATA GAPS

- 158.130 Environmental fate
  - 161-1 - Hydrolysis
  - 161-2 - Photodegradation In Water
  - 161-3 - Photodegradation on Soil
  - 161-4 - Photodegradation In Air
  - 162-1 - Aerobic Soil Metabolism Study
  - 162-2 - Anaerobic Soil Metabolism Study
  - 162-3 - Anaerobic Aquatic Metabolism Study
  - 163-1 - Leaching and Adsorption/Desorption Mobility Studies
  - 163-2 - Volatility (Lab) Mobility Studies
  - 163-3 - Volatility (Field) Mobility Studies
  - 164-1 - Soil Dissipation Studies
  - 164-3 - Forestry Dissipation Studies
  - 164-5 - Soil, Long-Term Dissipation Studies
  - 165-1 - Rotational Crops Accumulation Studies (confined)
  - 165-2 - Rotational Crops Accumulation Studies (field)
  - 165-4 - In Fish Accumulation Studies
  - 165-4 - In Aquatic Non-Target Organisms Accumulation Studies

- 154.140 Reentry Protection
- 158.135 Toxicology
  - 82-1 - 90-Day Subchronic Feeding - rodent
  - 83-1 - Chronic Toxicity - rodent (rat)
  - 83-2 - Oncogenicity - rat and mouse
  - 82-3 - Teratogenicity - 2 species
  - 84-2 - Gene Mutation
  - 83-2 - Chromosomal Aberration
  - 83-2 - Other Mechanisms of Mutagenicity

- 158.145 Wildlife and Aquatic Organisms]
  - 71-1 - Avian Acute Oral Toxicity
  - 71-2 - Avian Subacute Dietary Toxicity
  - 72-2 - Acute Toxicity To Freshwater Invertebrates

- 158.125 Residue Chemistry
  See under Tolerance Reassessment

                   6.  CONTACT PERSON AT EPA

William H. Miller
Product Manager (16)
Insecticide-Rodenticide Branch
Registration Division (T5-767C)

Telephone:  (703) 557-2600