carbophenothion (Trithion) Chemical Fact Sheet 5/84
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 25
DATE ISSUED: MAY , 1984
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
- 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.
- 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
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.
- 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
- 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
- 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
- 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%.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
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)
Registration Division (T5-767C)
Telephone: (703) 557-2600
DISCLAIMER: THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.