State
Environmental Protection
Agency
Of.cce of Pettic dec «nd Toxic ubstance*
OMice of Pestiode Programs (TS-766C)
Washington. DC 2O46O
xTfc
Pesticide
Fact Sheet
Name of Chemical:
Reason for Issuanoe:
Date Issued: JAN -
Fact Sheet Number:
Phosphamidon
Registration Standard
1988
154
Description of Chemical
Common Name: Phosphamidon
Chemical Name:
?-chloro-3-(diethylamino)-l-methyl-3-
oxo-1-propenyl dimethyl phosphate
Other Chemical Nomenclature:
Trade Names:
dimethyl phosphate ester
2-chloro-N,N-diethyl-3-
hydroxycrotonamide;
2-chloro-2-diethylcarbamoyl-
1-methylvinyl dimethyl
phosphate;
O,0-dimethyl-O-(2-chloro-
2-diethylcarbamoy1-1-
methylvinyl) phosphate
Apamidon; C570; Ciba 570; Dimecron; Dixon;
Dimenox
Chemical Class: Organophosphate
Empirical Formula: CioH^qClNO5P
Chemical Abstracts Service (CAS) Nos.:
13171-21-6 [(E)-+(Z)-isomers]
23783-98-4 [(Z)-isomerl
297-99-4 [(E)-isomer]
OPP Shaughnessv No.: 018201
Pesticide Type: Systemic insecticide/acaricide
Year of initial Registration: 1963
U.S. and Poreian Producers: Ciba-Geigy Corp., USA
Use Patterns and Formulations
Application sites:
terrestrial food crops — apple; apple
(nonbearing) ; broccoli; cantaloupe;
cauliflower; cotton; cucumber; grapefruit;
lemon; orange; peppers; potato; sugarcane;
tangerine; tomato; walnut; watermelon.
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Types of Formulation: Phosphamidon is marketed as an 8
lb ai/gal SC/L (soluble concentrate!
liquid), and is formuldted from a
single 89.5% technical product.
Types/Methods of Application: Phosphamidon is applied
by ground and aeriaL
application.
3. Science Findings
Summary Science Statements :
Phosphamidon is an organophosphate compound. The Agency
has no valid acute toxicity studies for phosphamidon,
although the Agency believes that phosphamidon is highly
toxic. No valid subchronic studies are available for
phosphamidon. A 2-year rat feeding study showed toxic
signs of choitnesterase inhibition activity in serum and
brain, decreased body weights, erythrocyte counts, hemoglobin
levels and, necrotic changes in the stomach and other
organs. Studies on the toxic effects of phosphamidon in
nonrodent species are not available. The submitted
oncogenicity data are considered inadequate to assess the
oncogenic potential of phosphamidon. Sufficient developmental
toxicity data are available to satisfy the regulatory
requirements in two species. Based on these data the
Agency concluded that phosphamidon did not demonstrate any
significant developmental toxic effects. The available
2—generation rat reproduction study satisfies this requirement.
No data are available to evaluate the mutagenic potential
of phosphamidon. No data on the metabolic pathway of
phosphamidon are available. Phosphamidon is acutely and
subacutely very highly toxic to a variety of avian species
and can be lethal to birds through dermal exposure. In
additiQn, available information indicate that delayed
mortality of birds occurs after applications of phosphamidon
(in some cases up to several weeks). Since available
information suggests that phosphamidon may have a relatively
short half—life, it is possible that some degradate is
toxic to birds. Based upon the fish and wildlife data
available, it is observed that technical phosphamidon is
very highly toxic to both coidwater and warmwater fish
species, aquatic invertebrates, and mammals. Available
data indicate that phosphamidon is highly toxic to honey
bees, predaceous mites, parasitic wasps, and predaceous
beetles.
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Chemical Characteristics :
Physical/chemical properties of pure phosphamidon and of
the technical phosphamidon.
Color: Colorless (PAI*), slightly amber oil (T*)
Physical State: Liquid (PAl)
Odor: Odorless, faint, mild (PAl)
Melting Point: Liquid at room temperature
Boiling Point: 160 °C, 1.5 mm (PAr)
Density: 1.2 at 20 °C (PAl)
Solubility: Miscible with water, alcohol, and ketones.
Highly solub1 e in aromatic and chlorinated
hydrocarbons, esters and ethers. Solubility
in hexane is 3.23 g/lOO g 25°C (PAl)
Vapor Pressure: 2.5 x lO- mm Hg at 20 °C (PAl)
Octanol/Water Partition Coefficient: Log P = 0.8 (PAl)
Stability in water: Half—life at 2 ppm and 38 °C is
70 hours at pH 9.1 and > 300
hours at pH 1.1 (PAl). Half—life
(in days) of phosphamidon in
buffered media (T):
Temperature
23 °C 45 °C
4 74 6.6
7 13.8 2.1
10 2.2 0.14
Toxicology Characteristics :
Acute oral: Data gap
Acute dermal: Data gap
Acute inhalation: Data gap
Primary dermal irritation: Data gap
Primary eye irritation: Data gap
Acutedelayed neurotoxicity: Data gap
Subchronic oral (nonrodent): Data gap **
Chronic feeding (nonrodent): Data gap
Oncogenicity : Data inadequate to assess oncogenic potential,
Study required in the mouse.
Metabolism: Data gap
Developmental Toxicity:
Rabbit - Maternal NOEL = 3 mg/kg
Maternal LEL = 10 mg/kg
Developmental NOEL = > 10 mg/kg
Rat — Maternal NOEL = 0.5 and 1 mg/kg
Developmental NOEL = 2 mg/kg
*pAI = Pure Active Ingredient, T = Technical
** Not required if an acceptable chronic study is submitted.
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Reproductive effects:
Rat — Parental F’OEL = 30 ppm (1.5 mq/kg/day)
Parental LEL 50 ppm (2.5 mg/kg/day)
Reproductive/Developmental
NOEL = 5 ppm (0.25 mg/kg/day)
Reproducti ye/Developmental
LEL = 30 ppm (1.5 mg/kg/day)
Mutagenicity: Data gap
Physiological and Biochemical Characteristics:
Metabolism and persistence in plants and animals
The metabolism of phosphamidon in plants and animals is
not adequately understood. Residues of [ 14 C] phosphamidon
were identified and quantitatively determined only in
immature bean plants. No edible livestock tissues (other
than milk) were analyzed for residues, and residues were
not characterized sufficiently in livestock. No poultry
data were submitted. The available plant metabolism data
indicate that phosphamidon degrades rapidly when applied
directly to the leaves of very young “two—leaf stage”
bean plants. The limited available ruminant metabolism
data indicate that phosphamidon is degraded rapidly in
animals, with most of the metabolic compounds being
excreted in the urine. Available data support the
established tolerances for residues of phosphamidon
including all of its related cholinesterase—inhibiting
compounds (as currently known) in or on the raw agricultural
commodities (RACs) potatoes, tomatoes, cucumbers, cottonseed,
and sugarcane. Note, however, that these tolerances,
including the residue definition, will be reassessed upon
receipt of the requested plant metabolism studies.
Ultimately, the tolerance definition will be changed to
list specific metabolites.
Environmental Characteristics :
Available data are not sufficient to allow the Agency to
fully assess the environmental fate of phosphamidon. The
available data suggest that phosphamidon is readily susceptable
to hydrolysis. Phosphamidon appears to be relatively
short lived in aerobic soil. N,N—diethyl—2-chloroacetoacetamide
and N—ethyl—2—chloroacetamide were identified as the two
major nonvolatile degradates, but the characterization of
degradates has not been completed. Phosphamidon residues
are considered to be highly mobile in soil. However, the
relative mobilities of the parent compound and its degradates
have not been adequately defined. Available data are not
adequate to fully assess the potential of phosphamidon to
contaminate ground water.
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Ecological Characteristics:
Avian Species
Technical phosphamidon is very highly acutely toxic to
birds as demonstrated by both acute and dietary studies.
Subacute dietary studies demonstrate that there is a
range of toxicity from 24 ppm (bobwhite quail) to 712 ppm
(mallard duck). Available data indicate that phosphamidon
can be toxic to birds through contact with head, feet or
through contact with sprayed foliage. Data indicate that
small doses picked up from perches or applied to the feet
of birds can be lethal. Special tests are being required
to determine the dermal toxi city of phosphamidon to
birds. Avian reproduction studies for phosphamidon are
not available. There are no data available on the toxicity
of degradates of phosphamidon to birds. Because delayed
mortality is an indicated adverse effect of phosphamidon
on birds, and because substantial reduction of populations
of songbirds have occurred several weeks after phosphamidon
applications to forests, it is possible that degradation
products of phosphamidon can result in such effects.
Aquatic Organisms
Acceptable acute toxicity tests with technical phosphamidon
indicate that phosphamidon is highly toxic to fish. The
acute toxicity tests with freshwater invertebrates indicate
that phosphamidon is very highly acutely toxic to aquatic
invertebrates. There are no acceptable data evaluating
the toxicity of technical phosphamidon to estuarine and
marine organisms. Phosphamidon may reach estuarine
environments from its use on citrus orchards. Acute
studies on the toxicity of phosphamidon to estuarine and
marine invertebrates are required. Aquatic invertebrate
life cycle studies are required to support the agricultural
use applications.
Wild Mammal Toxicity
There are no adequate data with which to assess the
toxicity of phosphamidon to mammals. The only study available,
which suggests a lethal dose of 18 mg/kg in the deer mouse,
indicates that phosphamidon may be highly toxic to wild
mammals. Although the Agency can draw no conclusions
regarding the potential toxicity of phosphamidon to mammals,
a wild mammal toxicity study is not being required at
this time. However, if the acute mammalian studies required
in the Toxicology Section indicate a rat acute toxicity
< 5 mg/kg then a wild mammal toxicity study will be required.
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Non—target Insects
Available data indicate that phosphamidon is highly toxic
to honey bees, predaceous mites, parasitic wasps, and
predaceous beetles.
Tolerance Reassessment
Tolerances (expressed as phosphamidon) for residues of
the insecticide phosphamidon (2—chloro—2—diethylcarbamoyl-
1—methylvinyl dimethyl phosphate) including all of its
related cholinesterase—inhibiting compounds have been
established in or on various raw agricultural commodities
(40 CFR 180.239).
Because of the extensive residue chemistry and toxicology
data gaps, the Agency cannot complete a tolerance reassessment.
4. Required Labeling and Regulatory Position Summary
Restricted Use Classification
All currently registered products containing phosphamidon
have been classified for Restricted Use (40 CFR 162.31)
due to the acute dermal toxicity to humans and residue
effects on avian and mammalian species.
Endangered Species Labeling
Refer to PR Notice 87—5, issued May 1, 1987, for endangered
species labeling statements for all end—use products
containing phosphamidon for use on cotton.
It is the Agency’s position that in order to remain in
compliance with FIFRA, all products containing phosphamidon
must include labeling which requires compliance with the
following precautionary measures, pending receipt and
evalu&tion of additional data which will allow the Agency
to fully assess the potential to induce adverse effects.
Protective Clothing, Equipment and Work Safety Statements
The use of maximum full body protective clothing/equipment
by mixers/loaders/applicators, and by field workers
entering treated fields prior to the end of the 48 hour
reentry interval is required.
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Reentry Interval
A 43—hour reentry inter ia1 is required for all agricultural
uses of phosphamidon. In addition, the use of protective
clothing is required for early reentry into treated
areas.
Tolerances
No tolerances or significant new food uses will be granted
until the Agency has received sufficient data to evaluate
the dietary exposure to phosphamidon.
5. Summary of Major Data Gaps
Toxicology Date Due *
Acute Oral Toxicity 9 Months
Acute Dermal Toxicity 9 Months
Acute Inhalation Toxicity 9 Months
Primary Eye Irritation 9 Months.
Primary Dermal Irritation 9 Months
Dermal Sensitization 9 Months
Acute Delayed Neurotoxicity (hen) 12 Months
Subchronic 90-day feeding (nonrodent)** 18 Months
Subchronic 21-Day Dermal 12 Months
Chronic Toxicity (nonrodent) 50 Months
Oncogenicity (mouse) 50 Months
Mutagenicity (Gene Mutation, Chromosomal
Aberration and Direct DNA Damage and
Repair Studies) 9 Months
Metabolism (rats) 24 Months
Environmental Fate/Exposure
Hydrolysis 9 Months
Photodegradat ion
In water 9 Months
In soil 9 Months
In air 9 Months
Metabolism
Aerobic Soil 27 Months
Anaerobic Soil 27 Months
Mobility
Leaching and Adsorption/Desorption 12 Months
Laboratory Volatility 12 Months
Dissipation Studies - Field
Soil Dissipation 27 Months
Confined Accumulation Study 39 Months
Fish Accumulation Study 12 Months
* Due date is measured from the date of receipt of Standard by
the registrant, unless otherwise indicated.
** Not required if an acceptable chronic study is submitted.
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Environmental Fate/Exposure (cont’d) Date Due*
Spray Jrift
Droplet Size Spectrum 24 Months
Drift Field Evaluation 24 Months
Ecological Effects
Acute Avian Oral Toxicity (Degradate) 9 Months
Acute Avian Dietary Toxicity (Degradate) - 9 Months
Avian Reproduction 24 Months
Avian Field Testing (Mammals, Birds) 24 Months
Special Avian Testing (Dermal Toxicity) 6 Months -
(acceptable
protocol)
Acute Toxicity to Estuarine and Marine
Organisms 12 Months
Fish Early Life Stage and Aquatic
Invertebrate Life cycle 15 Months
Aquatic Residue Monitoring 6 Months -
(acceptab]e
protocol)
Residue chemistry
Nature of Residues (Plants, Livestock) 18 Months
Residue Analytical Method (Plant, Animal) 15 Months
Storage Stability 18 Months
Magnitude of Residues (Field crops) 18 Months
6. Contact Person at EPA
William H. Miller, (PM—16)
Insecticide-Rodenticide Branch (TS-767)
401 M Street S.W.
Washington, D.C. 20460
Tel. No. (703-557—2600
DISCLAIMER: The information presented in this chemical
information Fact Sheet is for informational purposed only
and may not be used to fulfill data requirements f or pesticide
registration and reregistration.
* Due date is measured from the date of receipt of Standard by
the registrant, unless otherwise indicated.
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