United States office of Partiodw and Toxic Sutatencet
Environmenttl Protection Office of Pesticide Program* (TS-766C)
Agency Washington. DC 20460
Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuance: COMPLIANCE DATE FOR RESTRICTED USE
Date Issued: Feb- *• 1985
Fact Sheet Number: 22.1
1. Description of chemical
Generic name: 0-ethyl S-phenyl ethylphosphonodithioate
Common name: Fonofos
Trade name: Dyfonate
EPA Shaughnessy code: 041701
Chemical abstracts service (CAS) number: 944-22-9
Year of initial registration: 1967
Pesticide type: Insecticide
Chemical family: organophosphate
U.S. and foreign producers: Stauffer Chemical Co.
2. Use patterns and formulations
Fonofos is a soil applied insecticide used primarily on
corn (95%). It is used also on various vegetable crops,
ornamentals, home lawns and home vegetable gardens and
commercial turf. Fonofos is applied mainly with ground
equipment. Aerial applications are made to hybrid seed
corn. Application rates vary from 1-4 Ibs./acre. The
usual carrier is water.
3. Science Findings
Fonofos is a yellow liquid with a mercaptan-like odor.
The boiling point is 212°F (100°C) and the melting point
is -32°C at 0.3mm H Fonofos is almost insoluble in
water and miscible in common organic solvents.
Toxicology characteristics:
Technical fonofos is highly toxic based on acute
oral, dermal, eye and inhalation effects.
Results of toxicological studies on fonofos are as
follows:
-Oral LDjo , ranges from 3.16-18.5 mg/kg
-Dermal LD50, ranges from 121-359 mg/kg
-Primary Eye Irritation, negative to 0.01 ml; 0/6 dead
-Inhalation LC SQ, 0.9 mg/L (male and female combined)
-3 generation reproduction rat, reproductive and
fetotoxic NOEL= 31.6 ppm (highest dose tested)
-2 year dog feeding study - NOEL, ChE and non-cholinergic=
8 ppm; LEL, ChE and non-cholinergic= 60 ppm
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Available data are insufficient to fully assess the
toxicological properties of fonofos. Data gaps must be
filled in areas of neurotoxicity, subchronic and chronic
toxicity, oncogerticity and mutagenicity before a total
risk assessment can be made.
Physiological and Biochemical Behavioral Characteristics:
Fonofos is not absorbed by foliage and is not translocated
in the plant body. It is a cholinesterase inhibitor
and accumulates in carrots.
Envirionmental Characteristics:
Fonof os is immobile in sandy loom and silt loam soils.
It is mobile in quartz sand. It decomposes in aerobic
soils by microbes i 4—8 weeks. Fonofos is non—volitile
from soil but volatile from water. It degrades in aerobic
soils with a half like of 3—16 weeks. Fonofos is moderately
persistent.
Ecological Characteristics:
Fonofos is moderately to highly toxic to birds and highly
toxic to freshwater fish and salt water organisms.
Simulated avian field studies indicate granular treatments
ot fonofos may result in some mortality, as well as brain
AChE inhibition, but that effects are not likely to
diminish wildlife resources.
See under Data Gaps for additional data requirements.
Tolerance assessments:
Tolerances are established for residues of the insecticide
0—ethyl S—phenyl ethylphosphonodithioate, including its oxygen
analog 0—ethyl S—phenyl ethylphosphonothioate, in or on raw
agricultural commodities as follows (40 CFR 180.221):
0.5 part per million in or on asparagus.
0.1 part per million (negligible residue) in or on bean
forage, bean vine hay, fresh corn including sweet corn
(kernels plus cob with husk removed), corn grain (in-
cluding popcorn), corn forage or fodder (including
sweet corn, field corn, and popcorn), fruiting vege-
tables, leafy vegetables, mint (peppermint, spearmint,
peppermint hay, and spearmint hay), pea forage, pea
vine hay, peanuts, peanut forage, peanut hay, peanut
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fact sheet
hulls, root crop vegetables, seed and pod vegetables,
sorghum (grain, fodder, and forage), soybean forage,
soybean hay, strawberries, sugar beet tops, and
sugarcane.
4. Summary of Regulatory Position and Rationale :
The Agency has determined that certain formulations of
fonofos warrant classification as restricted use pesticides.
These include all emulsifiable concentrates 44% or greater
and the 20% granular formulation. All products of these types
which are released for shipment after September 1, 1985 must
be labeled for restricted use. All products of these types
which are in channels of trade after September 1, 1986 must
be labeled for restricted use.
A 24 hour interim reentry interval has been established
for all uses of fonofos including the home lawn and home
vegetable garden use.
Gloves and shoes must be worn when applying fonofos.
5. Summary of Major Data Gaps *
o Delayed neurotoxicity — hen
o 90 day rodent feeding study
o 90 day neurotoxicity study — hen/mammal
O Chronic toxicity study—rodent
o Oncogenicity study
o Teratogencity study — 1 species
o Gene mutation study
o Chromosornal aberration study
o Reentry Data
o Acute LC 50 — freshwater invertebrates
O Fish early life cycle stage and aquatic invertebrate
lifecycle studies
o Residue data in:
— root and tuber vegetables
— leaves of root and tuber vegetables
— fruiting vegetables (except curcubits)
— cereal grains
— forage, fodder and straw of cereal grains
— miscellaneous crops ( asparagus, peanuts,
sugarcane and tobacco)
o Poultry feeding study and ruminant feeding study
o Photodegradation in water, soil and air
O Hydrolysis study
0 Metabolism study in anaerobic soil
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o Mobility studies (leaching and adsorption/desorption,
volatilty lab, and volatility field)
o Soil dissipation study
o Accumulation studies — rotational crops and fish
*A1l major data gaps are to be filled by March 31, 1987.
6. Contact person at EPA (Name, address, and telephone number)
Contact Person
William H. Miller, PM 16
Registration Division (TS—767)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street SW
Washington, DC 20460
(703) 557—2600
DISCLAIMER: The information presented in this Chemical
Information Fact Sheet is for informational purposes only and
may not be used to fulfill data requirements for pesticide
registration and reregistration.
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