oYc
U*"t«d St»t«i Otllci of Panicidai and Toxic Subtuneai
Environmental Protection Offlot of P«tidd« Program* (TS-7MCI
A«tncy Wvhington, DC 20460
vvEPA Pesticide
Fact Sheet
Name of Chemical: dichlorvos
Reason for Issuance: registration standard
Date Issued: io/87
Fact Sheet Number:
1. DESCRIPTION OF CHEMICAL
Generic Name: 2,2-dichlorovinyl dimethyl phosphate
(Chemical) hexahydro-4,7-methanoindene
Common Name: Dichlorvos
Trade and
Other Names: 2,2-dichloroetheny1 dimethyl phosphate;
DDVP (USA); DDVF (USSR). Nogos; Vapona;
Dedevap; Matu; Oko; Atgard; No-pest;
Herkol; Ciovap; Ravap; Vaponite; Canogard;
Equigard; Task and Riton.
EPA Shaughnessy Code: 084001
Chemical Abstracts Service (CAS) Number: 62-73-7
Year of Initial Registration: 1948
Pesticide Type: Insecticide
Chemical Family: Organophosphate
U.S. and Foreign Producers: Amvac Chemical Corp.; SDS Biotech
Corp.; Prentiss Drug and Chemical
Co.; Dow Chemical Corp; Kaw Valley;
MGK Co.; Denka Chemia B.V.; Kenco
Chemical and Mfg. Corp.; Wesley
Industries. Inc; Fermenta Animal
Health; and E.I. du Pont de Nemours
and Company
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2* USE PATTERNS AND FORMULATIONS
Application Sites: Dichlorvos is used in areas where flies,
mosquitoes, gnats, cockroaches and other
nuisance insect pests occur. Use sites
include the following:
in and around domestic dwellings (contract,
crack and crevice, bait, resin strip, and
space spray); direct application to
domestic food animals (spray, pour-on,
dip, back rubber, face oiler, and pa int
and impregnated material); direct application
to domestic animals (spray, flea collar,
and tag); in and around premises housing
animals (food and nonfood) (space spray,
bait, resin strip, and contact); ornamental
and food crop greenhouse use (contact and
space spray); mushroom houses (contact
and space spray); tobacco warehouses
(contact and space spray); postharvest
tomato treatment (dust applied to fruit
in containers); sewage plants/sewage
systems (resin strips and direct applica-
tion to sewage); aircraft, buses and other
commercial transportation vehicles (space
spray); nonperishable bulk-stored raw
agricultural commodities (RACs) (including
animal feed, beans [dried type], cocoa
beans, coffee beans, grain crops such as
corn, nut crops, peanuts, peas [field],
soybeans, and tobacco) (resin strip and
space spray); nonperishable packaged or
bagged RACs (including beans (dried
type], cocoa beans, coffee beans, grain
crops such as corn, nut crops, peanuts,
peas, and soybeans) (space spray); non-
perishable packaged or bagged processed
agricultura1 commodities (including
cereals, crackers, flour, packaged cookies,
and sugar); lawns (foliar application);
ornamental turf (foliar application);
ornamental plants (foliar and bark
application); noncrop aquatic areas
(ground or air equipment and resin strip);
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eating establishments, and food
processing and storage areas (space
spray, contact, bait, and resin strip);
other commercial, institutional and
industrial areas (space spray, contact
bait, and resin strip); enclosed outdoor
utility equipment (space treatment);
gypsy moth traps and malaise (tent)
traps (resin strip); figs (EPA SLN
No. CA-830045) (ground and air equip-
ment); urban and rural outdoor areas
(food and nonfood); including screwworm
adult suppression (EPA SLN Nos. TX-780056,
AZ-8003100, NM-790003, CA-810040) and
recreational areas (spray, bait, and
resin strip); and miscellaneous sites
including epcot display crops (EPA SLN
Nos. FL-8 20051, FL-820054, FL-820055),
rat receptacle bags, refuse and solid
waste containers and sites (spray, bait,
and resin strip).
Formulation Types: Emulsifiable concentrates, soluble
concentrate liquids, granulars, pressurized
liquids and dusts, impregnated materials,
pellets/tablets, liquids (ready to use),
wettable powders and dusts.
3. SCIENCE FINDINGS
Summary Science Statement
Dichlorvos is an organophosphate insecticide with moderate
to high acute toxicity. Dichlorvos is classified as a B2
"Probable Human Carcinogen", is a potent cholinesterase
inhibitor, and may cause liver effects from subchronic and
chronic exposure. Dichlorvos is potentially highly to very
highly toxic to fish and other wildlife. It may have the
capacity under various use patterns, i.e., fig and mosquito
larvicide use, to cause adverse effects to aquatic invertebrates,
fish, and birds. Dichlorvos degrades fairly rapidly in soil
and water and is therefore not expected to reach groundwater.
However, the environmental fate is largely uncharacterized,
and additional data are needed before definitive conclusions
are reached. A tolerance reassessment of dichlorvos is not
possible because of gaps in the toxicology data base and
because many of the tolerances are not adequately supported.
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Chemical/Physical Characteristics of the Technical Material
Physical State: Liquid
Color: Colorless to light amber
Molecular Weight and Formula: 221.0 - C4H7CI2O4P
Boiling Point: 117" C at 10 mm Hg
Specific Gravity: 1.42 at 25* C
Density: 1,65-1.67 g/ml
Vapor Pressure: 0.032 mm Hg at 32 "C
Solubility in Various Solvents: Slightly soluble in water
and kerosene; readily solu-
ble in most organic solvents
Stability: Stable in the presence of hydrocarbon solvents;
undergoes hydrolysis in the presence of water
and is readily decomposed by strong acids and bases
Miscibility: Miscible with most organic solvents and aerosol
propellants
Corrosion Characteristics: Corrosive to steel,* noncorrosive
to stainless steel, aluminum,
nickel, Hostelloz 13, Teflon
Chemical Relationships5 Trichlorfon and naled are chemically
related to dichlorvos. Naled degrades
to dichlorvos in plants, animals, and
soi1. In cattle and poultry, naled is
debrominated to dichlorvos which furth'
degrades to dichlorodesmethyl-dichlors
(major pathway) or desmethyl-dichlorvob
(minor pathway). Trichlorfon degrades
to dichlorvos in soil and alkaline pond
water, and possibly in plants and animals.
Toxicology Characteristics
Acute Oral: Toxicity Category II (56 and 80 rag/kg in female
and male Sherman rats, respectively).
Acute Dermal: Toxicity Category I (75 and 107 mg/kg in
female and male Sherman rats, respectively).
Primary Dermal Irritation: Toxicity Category IV based on
mild dermal irritation reported
in a rabbit study.
Primary Eye Irritation: Toxicity Category III based on
a lack of corneal injury and only
mild redness and chemosis at 24
hours postapplication of 1.67 mg/kg
technical dichlorvos in rabbits'
eyes.
Skin Sensitization: Data Gap
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Acute Inhalation: Toxicity Category I based on a toxicity
value of >193 mg/m3 in rats.
Delayed Neurotoxicity: Data Gap
Subchronic Oral (rodent) Testing: Data Gap
Oncogenicity: Classified as a B2 "probable human carcinogen"
This determination for oncogenicity is based
on a draft report of a review of two rodent
studies sponsored by the National Toxicology
Program in which there were significantly
increased incidences of forestomach squamous
cell carcinoma/papillomas in female mice and
pancreatic acinar adenomas, mononuclear cell
leukemia and lung adenomas in male rats ana
mammary gland fibroadenomas in female rats.
The potency or is 2.9 x 10-1 (mg/kg/day).
Chronic Feeding: Based on a dog chronic feeding study with
increased relative liver weights in males
at 32 ppm and above, and enlargement of
liver cells in both sexes at 32 ppm and
above, the no-observable-effect level
(NOEL) is 0.0b mg/kg/day (3.2 ppm). A
rodent feeding study is required.
Metabolism: Data Gap
Teratogenicity: Rodent teratology study is a data gap,- based
on an acceptable rabbit teratology study by
inhalation, the NOEL for embyro/fetotoxicity
is 2 ug/L based on decreased fetal weights.
Data Gap
Dichlorvos is a direct-acting (gene) mutagen,
in bacteria, fungi, and mammalian cells
in vitro. Dichlorvos was shown to be negative
in micronucleus and sister-chroraatid exchange
assays conducted in mice, and was also negative
in repeated dominant lethal assays.
Major Routes of Exposure: Dermal and respiratory exposure to
mixers, loaders, applicators,
reentry workers and occupants of
treated buildings.
Reproduction:
Mutagenicity:
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Environmental Characteristics
Numerous data gaps exist for environmental fate. Data reviewed
by the Agency indicate that dichlorvos degrades fairly rapidly
with half-lives of 2 to 8 hours in soils ranging in texture
from sand to silt. The mobility of dichlorvos is inversely
correlated with soil organic matter content. Preliminary
data also suggest that dichlorvos is intermediately to very
mobile in a variety of soils ranging in texture from sandy
loam to clay. Groundwater contamination may not be a problem
because of dichlorvos's rapid degradation. However, acceptable
data are lacking, and are needed before the Agency can assess
the potential for dichlorvos to contaminate groundwater.
Ecological Characteristics (technical grade)
Avian oral toxicity: Data Gap
Avian dietary toxicity: Acute toxicity values greater
(8-day) than 1317 and 5000 ppm for
mallard ducks at 5 and 16 days
of age, respectively; for phea-
sants the acute toxicity value
is 568 ppm.
Freshwater fish acute toxicity: 0.1 ppm for rainbow
(96-hr. LC50) trout;
0.23 ppm for striped
mullet.
Estuarine/marine fish acute toxicity: 0.23 for striped
mullet
Freshwater invertebrate toxicity: 0.00007 ppm for Daphnia
(48-hr. or 96 hr. EC50) pulex; 0.004 ppm for
sand shrimp.
Estuarine/marine invertebrate toxicity: 0.0004 ppm for
sand shrimp
Tolerance Reassessment
Analytical methodology for determining the levels of
residues of dichlorvos in plants and animals is adequate
for data collection of residues in plant commodities and in
animal tissues and milk. Storage stability data demonstrate
that residues of dichlorvos in or on frozen plant samples
are stable up to 90 days after application. Residues in or
on frozen animal tissues are stable up to 8 weeks after
application. Additional storage data (length of time and
conditions under which samples were stored) are required
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in order to evaluate the adequacy of the dichlorvos tolerances.
If previously submitted samples or newly generated samples
were/are stored frozen for greater than 90 days (plants)
or 8 weeks (animals), additional storage stability data
will also be needed. Data on the magnitude and levels of
residues of dichlorvos in radishes, lettuce, tomatoes,
cucumbers, milk, eggs, and the meat, fat, and meat byproducts
of cattle, goats, hogs, horses, sheep, and poultry are
insufficient to determine the adequacy of the established
tolerances. Tolerances for residues of dichlorvos in or on
figs, dried figs, and mushrooms are adequately supported.
Data are required to support use of dichlorvos products in
food areas of food handling establishments. Processing and
cooking studies are required. Data reflecting the use of ~
dichlorvos on stored, unfinished tobacco are required. The
established tolerances for residues of dichlorvos in or on
bulk-stored nonperishable RACs are not adequately supported,
and data are required. The established tolerances are adequate
to cover residues of dichlorvos in or on packaged or bagged
nonperishable RACs and processed food resulting from the
application of dichlorvos vapors. However, the data indicate
that residues following use of aerosol treatments will result
in toleranceexceeding residues. Therefore, residue data and
an accompanying tolerance revision must be submitted. Also,
insufficient data are available regarding residues of dichlorvos
in the meat, fat, and meat byproducts of cattle, goats,
horses, sheep, and poultry and milk and eggs. This constitutes
a data gap.
Based on a 2-year dog feeding study with a NOEL of
0.08 mg/kg/day (3.2 ppm) for changes in liver weight and
enlarged liver cells, a provisional acceptable daily intake
(PADI) of 0.0008 mg/kg/day has been calculated using a one
hundred-fold uncertainty factor. The calculated estimate is
provisional because the existing data base for dichlorvos is
lacking a chronic rat feeding study, a reproduction study and
a rat teratology study. The Anticipated Residue Contribution
(ARC) for dichlorvos for the U.S. population average is
0.000416 mg/kg/day based on current tolerance levels, cooking
data for small grains, and an estimate of percent crop treated.
The ARC occupies 52% of the PADI. For children 1 to 6 years
of age, the ARC occupies 122% of the PADI.
4. SUMMARY OF REGULATORY POSITIONS AND RATIONALES
* The Agency is considering further regulatory act ion for
all registered uses of dichlorvos because of concerns about the
risks of oncogenicitv, cholinesterase inhibition, and liver
effects. The risks of concern are for the public from consumption
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risks ot oncogenicity, cholinesterase inhibition, and liver
effects. The risks of concern are for the public from consumption
ot foods containing residues ot dichlorvos, for those involved in
the application ot dichlorvos, for workers reentering treated
areas, tor residents/occupants of treated areas (including areas
treated with resin pest strips or other dichlorvos products), for
people exposed to pets treated with dichlorvos, and tor pets
treated with dichlorvos.
0 In order to meet the statutory standard tor continued
registration, the Agency has determined that all dichlorvos
products (excluding domestic uses [household sprays containing
0.5% or less active ingredient], resin strips and pet uses)
must be restricted for retail sale to and use by Certified
Applicators or persons under their direct supervision. In
view ot the potential health hazards associated with exposure
to dichlorvos, the Agency is concerned about exposure to
dichlorvos which may result from improper application or
use ot dichlorvos products, and so is restricting use ot
the pesticide.
° In order to meet the statutory standard tor continued
registration, the Agency has determined that all products
must contain a cancer hazard warning. The Agency believes
that incorporation of this statement attords the product
user with important information about the potential
oncogenic hazard associated with the use of the product.
° The Agency has determined that in order to meet the statutory
standard for continued registration, all dichlorvos product
labels must bear protective clothing statments.
° An interim 48-hour reentry interval is imposed tor the
agricultural and commercial uses ot dichlorvos until such
time as appropriate reentry data have been submitted and
evaluated. Exposure data are required to support
registration ot total release foggers and aerosol products
intended tor use in domestic dwellings.
0 Pesticide spray dritt data requirements are imposed for the
fig use and outdoor aerosol and fogging mosquito use. Data
required include droplet size spectrum studies and tield
evaluation ot pesticide spray drift.
° The Agency is requiring a special environmental monitoring
study in order to evaluate whether or not the tig and mosquito
control uses ot dichlorvos may result in exposure ot certain
terrestrial and aquatic organisms to potentially hazardous
levels ot the pesticide.
o The Agency has determined that endangered species label
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o In order to remain in compliance with FIFRA, the Agency has
determined that endangered species label restrictions
are necessary to protect endangered threatened species in
aquatic areas. Labeling which prohibits the mosquito larvicide
use of dichlorvos in the range of endangered and threatened
species is required through PR Notice 87-4, which was issued
in May, 1987. Additional endangered species labeling require-
ments are reserved pending the results of a consultation with
the Office of Endangered Species regarding use of dichlorvos
on figs.
* The Agency is deferring decisions concerning dichlorvos
and groundwater contamination until such time as the
information required by the Standard have been submitted
and reviewed.
No new tolerances for raw agricultural commodities or
new food uses will be granted until data gaps for
residue chemistry and chronic toxicology have been
t ilied.
All products must bear appropriate labeling as specified
in 40 CFR 162.10, PR Notices 83-2, 83-3, and 87-4,
precautions and warnings listed in the Dichlorvos Use
Index, and as indicated in the Registration Standard.
6. SUMMARY OF OUTSTANDING DATA REQUIREMENTS
Toxicology
Dermal sensitization
Dermal absorption
21-day dermal toxicity
Neurotoxicity
Subchronic oral toxicity
Chronic feeding - rodent
Teratogenicity - species
- rodent species
species
other than the rabbit
Reproductive effects
Metabolism
rats (2-generation)
Time Frame
9 Months
6 "
9 "
9 "
12 "
50 "
15 "
39 "
24 "
Environmental Fate/Exposure
Hydrolysis study 9 Months
Aerobic soil metabolism study 27
Aerobic and anaerobic aquatic metabolism study 27 "
Leaching and adsorption/desorption study 12
Terrestrial field dissipation study 27
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Aquatic (sediment) - field study 27
Photodegradation in water, soil and air 9
Volatility (lab) studies 12
Accumulation - irrigated crops 39
Reentry data 18
Dermal and inhalation Exposure 18
Spray drift data 18
Residue Chemistry
Livestock metabolism (direct animal treatment) 18 Months
Storage stability data 18 "
Residue analytical Method 15 "
Residue data {except 18 "
for figs, dried figs, and mushrooms) 18
Processing and cooking studies 18
Residue data on stored, unfinished tobacco 18 "
Residue data -food handling establishements 12
Product Chemistry 9-15 Months
Fish and Wildlife
Acute avian toxicity 9 Months
Acute toxicity to fish 9
Acute toxicity to freshwater invertebrates 9 "
Acute toxicity to estuarine and marine organisms 9
Fish early life stage and aquatic invertebrate
life-cycle 15 "
Special environmental residue monitoring study 24 "
Avian reproduction 24 "
Fish life cycle study 27
Honeybee - toxicity of residues on foliage 15
7. CONTACT PERSON AT EPA
George LaRocca
Product Manager (15)
Insecticide-Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street SW.
Washington, DC 20460
Office location and telephone number:
Room 204, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202
(703) 557-2400
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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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