fensulfothion (Dasanit) Chemical Fact Sheet 9/83
CHEMICAL FACT SHEET FOR:
FENSULFOTHION
FACT SHEET NUMBER: 14A
DATE ISSUED: SEPTEMBER, 1983 DATE UPDATED: FEBRUARY 28, 1985
1. DESCRIPTION OF CHEMICAL
- Generic Name: O,O-diethyl O-[p-(methylsulfinyl)phenyl]
phosphorothioate
- Common Name: fensulfothion
- Trade Names: Dasanit, BAY 25141, S-767, TERRACUR P
- EPA Shaughnessy Code: 32701
- Chemical Abstracts Service (CAS) Number: 115-90-2
- Year of Initial Registration: 1965
- Pesticide Type: Insecticide/nematicide
- U.S. and Foreign Producers: Mobay Chemical Corporation
2. USE PATTERNS AND FORMULATIONS
- Fensulfothion is registered for use as preplant or at-planting soil
application to tobacco and various fruits and vegetables. Postplant
topical applications are permitted in addition to the at-planting
application on corn, peanuts, and rutabagas. Topical application is
also permitted on commercial and ornamental turf.
- Fensulfothion is formulated into a 63% (6 lb./gal.) E.C. (restricted
use), 10% and 15% granulars, and at various percentages with
disulfoton, thiram, or pebulate.
3. SCIENCE FINDINGS
Chemical Characteristics
Technical fensulfothion is a brown liquid organophosphate, stable
under normal use conditions, with a boiling point of 138-141 degrees C
at 0.01 mm Hg. It is soluble in most organic solvents except
aliphatics. The chemical is acutely toxic, and extreme caution is
necessary in handling of contaminated articles and during mixing,
loading, and application. Respirator and protective clothing are
required during these operations.
Toxicological Characteristics
- Fensulfothion is highly toxic (Tox Category I) from acute oral and
dermal routes of exposure.
- Many of the toxicology studies do not meet present guideline
requirements and need to be replaced; however, no significant risks
have been identified from the existing data base.
- Toxicology studies on fensulfothion are as follows:
- Oral LD50 in rats: 2.2 mg/kg (female), 10.5 mg/kg (male)
(Acceptable)
- Dermal LD50 in rats: 3.5 mg/kg (female), 30.0 mg/kg (male)
(Acceptable)
- Acute delayed neurotoxicity in chickens: none observed
(Supplementary)
- Metabolism study in rats: (Acceptable)
- 90-day feeding, rodent, non-rodent: (Supplementary: invalid -
data gap)
- Chronic toxicity, non-rodent: (Invalid - data gap)
- Chronic toxicity, rodent: No NOEL found (Supplementary)
- Oncogenicity, rat: (Supplementary)
- Teratogenicity, rabbit: (Supplementary)
- Reproduction study: NOEL 1 or 4 ppm (Supplementary)
- Mutagenicity, gene mutation: Negative (Partially satisfied
study)
Physiological and Biochemical Behavioral Characteristics
- Fensulfothion is an organophosphate insecticide/nematicide that
kills primarily by contact action, but also provides some systemic
control of insects attacking the foliage of treated plants.
- The mode of action is by phosphorylating the acetylcholinesterase
enzyme of tissues, allowing accumulation of acetylcholine at nerve
junctions, with subsequent blocking effects upon the central
nervous system.
- The metabolism of fensulfothion is basically similar in both plants
and animals. By the processes of hydrolysis, oxidation, and
reduction, the parent compound may be broken down to 13 known
metabolites, 5 of which are themselves cholinesterase inhibitors.
On the basis of this knowledge, all presently established
fensulfothion tolerances are expressed in terms of the combined
residues of the parent compound and these five cholinesterase-
inhibiting metabolites. Fensulfothion is metabolized fairly
rapidly by both plants and animals. In animals, hydrolytic
degradation in liver and other tissues results in excretion of low
toxicity degradation products, with half the pesticide eliminated
within 24 hours and almost total elimination of the pesticide and
its metabolites within a week.
Environmental Characteristics
- Fensulfothion is degraded in soils under aerobic conditions with
half-lives of 3-28 days, due to microbial degradation. Half-life
is rapid in silty clay loam and organic soil (3-7 days), and
fairly rapid in sandy loam, silt loam, and loam soils (around 28
days). Fensulfothion degrades rapidly in the water and silt of a
simulated pond with half-lives of 10 and 12 days, respectively.
- The mobility of fensulfothion and aged residues is low to moderate
in a wide range of soils. Dissipation of fensulfothion is fairly
rapid from field soils, with half-lives ranging from <30 days to
>182 days.
- Fensulfothion residues are taken up by rotational crops grown in
the greenhouse, but are not taken up by field rotational crops.
- Available data are insufficient to fully assess the fate of
fensulfothion in the environment; however, groundwater contamina-
tion does not appear to be a problem with this chemical.
- Fensulfothion has a low potential to bioaccumulate in bluegill
sunfish.
- Data are insufficient to fully assess the exposure of humans and
non-target organisms to the chemical or its degradates; however,
human exposure should be minimal by use of current restricted use
classification and labeling precautions requiring approved
respirators and protective clothing.
- Exposure during reentry operations should be minimal; however, data
are not available to fully assess such exposures. A 7-day reentry
period is being required for unprotected workers following soil
application if the soil is wet. A 24-hour reentry period is being
required for applications of fensulfothion where agricultural
practice will involve hand labor with prolonged, intimate foliar
contact, or if the soil is dry.
Ecological Characteristics
- Avian oral LD50: 0.749 ppm (very high toxicity)
- Avian dietary LC50: 22 ppm (high toxicity)
- Fish LC50: 0.07 ppm (very high toxicity)
- The toxicity of fensulfothion to terrestrial and aquatic non-target
organisms is very high. Residue calculations indicate that three
RPAR triggers (mammalian, avian, and aquatic) may be exceeded. In
all cases, the Standard has asked for Tier III data (field studies)
to gather qualitative and quantitative data to support the regis-
tration and/or need for special review.
- Because of fensulfothion's extensive number of use patterns and its
high toxicity to wildlife, numerous endangered species have been
identified that could be impacted. The Agency is currently
considering various approaches to address the problem for this and
other chemicals, and the Standard may be amended to incorporate
the results of this additional review.
Tolerance Assessment
- The following tolerances (in parts per million) have been established
for fensulfothion:
International
Commodity U.S. Canada Mexico (Codex)
Bananas 0.02 - - 0.02
Beets, sugar 0.05 - - -
Beets, sugar, tops 0.05 - - -
Cattle, fat 0.02 - - 0.02
Cattle, MBYP 0.02 - - 0.02
Cattle, meat 0.02 - - 0.02
Corn, field, fodder 1.0 - - -
Corn, field, forage 1.0 - - -
Corn, fresh (inc.
sweet) (K+CWHR) 0.1 0.1 - 0.1
Corn, grain 0.1 0.1 - 0.1
Corn, pop, fodder 1.0 - - -
Corn, pop, forage 1.0 - - -
Corn, pop, grain 0.1 0.1 - 0.1
Corn, sweet, fodder 1.0 - - -
Corn, sweet, forage 1.0 - - -
Cotton, seed 0.02 - - -
Goats, fat 0.02 - - 0.02
Goats, MBYP 0.02 - - 0.02
Goats, meat 0.02 - - 0.02
Hogs, fat 0.02 - - -
Hogs, MBYP 0.02 - - -
Hogs, meat 0.02 - - -
Horses, fat 0.02 - - -
Horses, MBYP 0.02 - - -
Horses, meat 0.02 - - -
Onions, dry bulb 0.1 0.1 - 0.1
Peanuts 0.05 - - 0 05
Peanuts, hulls 5.0 - - -
Pineapples 0.05 - - 0.05
Pineapples, forage 0.05 - - -
Plantains 0.02 - - -
Potatoes 0.1 0.1 - 0.1
Rutabagas, roots 0.1 0.1 - 0.1
Sheep, fat 0.02 - - 0.02
Sheep, MBYP 0.02 - - 0.02
Sheep, meat 0.02 - - 0.02
Sorghum, fodder 1.0 - - -
Sorghum, forage 1.0 - - -
Sorghum, grain 0.1 - - -
Soybeans 0.02 - - -
Soybeans, forage 0.1 - - -
Sugarcane 0.02 - - -
Sweet potatoes 0.05 - - -
Tomatoes 0.1 - - 0.1
- Most tolerances for residues are supported with data; however,
additional data must be submitted to support tolerances for
residues in or on the following commodities: bananas, peanuts,
peanut hulls, plantain, and potatoes (processing data only).
- There is no reasonable expectation of finite residues in milk,
eggs, poultry meat, fat, or meat byproducts, and no tolerances are
required.
Summary Science Statement
Fensulfothion is an organophosphate insecticide/nematicide of high
toxicity to man and other non-target terrestrial and aquatic
organisms. Tier III data (field studies) have been requested in
response to the three RPAR triggers (mammalian, avian, and aquatic)
that have been exceeded. The current NOEL, ADI, and MPI are now
only partially supported by data, but will be used in the interim.
Available data are insufficient to fully assess the toxicology of
fensulfothion, its fate in the environment, or the exposure of
humans and non-target organisms to the chemical or its degradates.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- The previous Restricted Use classifications required in 40 CFR
162.31 will be continued. In addition, granular formulations are now
being restricted. All granular formulation products released from
shipment after September 1, 1985, must be labeled for restricted use.
Also, all products still in channels of trade after September 1,
1986, must be labeled for restricted use.
- The following Environmental Hazards text will be required on manu-
facturing use products because of the hazards posed to non-target
terrestrial and aquatic wildlife: This product is toxic to fish
and extremely toxic to wildlife. Do not discharge into lakes,
streams, ponds, or public waters unless in accordance with an NPDES
permit. For guidance, contact your Regional Office of the EPA.
- The following environmental statements are required for end-use
products: This product is toxic to fish and extremely toxic to
wildlife. Use with care when applying in areas frequented by
wildlife. Birds feeding on treated areas may be killed. Cover,
disc, or incorporate spill areas. Drift and runoff from treated
areas may be hazardous to aquatic organisms in neighboring areas,
Do not apply directly to water or wetlands. Do not contaminate
water by cleaning of equipment or disposal of wastes. This product
is highly toxic to bees exposed to direct treatment on blooming
crops or weeds. Do not apply this product or allow it to drift to
blooming crops or weeds while bees are actively visiting the treat-
ment area.
- The following reentry precautions are required on end-use products
in the interim until requested reentry data has been received and
reviewed by the Agency: Unprotected workers should not re-enter
treated fields until 24 hours after application. Unprotected
workers should not re-enter fields where the soil is wet until 7
days after soil application.
- Reported pesticide incidents involving fensulfothion alone between
1966 and 1983 include 25 involving human injury and 4 involving
animals. Most of the human incidents resulted from failure to use
safety equipment while applying fensulfothion. Other incidents
were the result of improper disposal, handling, or storage.
Because the incidents involve occasions of misuse, no additional
precautionary statements are necessary at this time to minimize the
risk of injury.
5. SUMMARY OF MAJOR DATA GAPS
- Product Chemistry Due Date
- Description of manufacturing process 6/84
- Description of formation of impurities 6/84
- Preliminary analysis 6/84
- Certification of limits 6/84
- Odor 6/84
- Solubility 6/84
- Vapor pressure 6/84
- Dissociation constant 6/84
- Octanol/water partition coefficient 6/84
- pH 6/84
- Analytical method for enforcement of limits 6/84
- Oxidizing or reducing action 6/84
- Flammability 6/84
- Explodability 6/84
- Viscosity 6/84
- Miscibility 6/84
- Residue Chemistry
- Storage stability 1/87
- Processed food/feed studies on potatoes 1/87
- Crop field trials on bananas, peanuts, and
plantain 1/87
- Toxicology
- Inhalation LC50 - rat 6/84
- Acute delayed neurotoxicity - hen 6/84
- 90-day feeding - rodent, non-rodent 1/87
- 90-day inhalation - rat 1/87
- Chronic toxicity - 2 species 1/87
- Oncogenic study - 2 species 1/87
- Teratogenicity - 2 species 1/87
- Reproduction - 2 generation 1/87
- Gene mutation 1/87
- Chromosomal aberration 1/87
- Wildlife and Aquatic Organisms
- Avian reproduction 1/87
- Simulated and actual field testing (mammals
and birds) 1/87
- Acute LC50 freshwater invertebrates 1/87
- Acute LC50 estuarine and marine organisms
(shrimp, marine fish, and oyster) 1/87
- Fish early life stage and aquatic invertebrate
life cycle 1/87
- Environmental Fate
- Hydrolysis 1/87
- Photodegradation in water 1/87
- Anaerobic soil metabolism 1/87
- Volatility 1/87
- Soil dissipation 1/87
- Accumulation in rotational crops 1/87
- Accumulation in fish 1/87
- Reentry Protection
- Foliar dissipation 1/87
- Soil dissipation 1/87
- Dermal exposure 1/87
- Inhalation exposure 1/87
6. CONTACT PERSON AT EPA
George T. LaRocca
Product Manager 15
Insecticide/Rodenticide Branch (TS-767C)
401 M Street
Washington, DC 20460
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.
Disclaimer: Please read
the pesticide label prior to use. The information contained at this web
site is not a substitute for a pesticide label. Trade names used herein
are for convenience only; no endorsement of products is intended, nor is
criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
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