United States Office of Pesticides and Toxic Substances
Environmental Protection Office of Pesticide Programs (H7508C)
Agency Washington, DC 20460
•£EPA Pesticide
Fact Sheet
540/FS-90-075
Name of Chemical: ETHION
Reason for Issuance: Registration Standard
(Second Round Review)
Date Issued: September 30, 1989
Fact Sheet Number: 209
DESCRIPTION OF CHEMICAL
Generic (Chemical) Name: 0,0,0',0'-Tetraethyl S,S'-
methylene bisphosphorodithioate
Common Name: Ethion
Trade and Other Names: Ethanox, Ethiol, Hylemox, Rhodiacide,
Rhodocide, Vegfru Fosmite, RP-Thion,
Tafethion.
EPA Pesticide Chemical Code (Shaughnessy No.): 0584401
Chemical Abstracts Service -(CAS) Number: 563-12-2
Year of Initial Registration: 1965
Pesticide Type: Insecticide (non-systemic)
Chemical Family: Organothiophosphate member of the
Organophosphate Family
U.S. and Foreign Producers:
Cheminova (Denmark)
FMC Agricultural Chemical Group (USA)
M/S Pesticides India (India)
Rallis India Ltd.
Rhone-Poulenc Agrochemic (France)
Sintesul S.A. (Brazil)
Volrho Ltd. (India)
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2. Use Patterns and Formulations
Application: A non-systemic insecticide for control of leaf-
feeding insects, mites, and scale.
Registered Uses:
Terrestrial Non-food Crops: Bermudagrass,
junipers, ornamental evergreens, pine trees,
lawns, ornamental turf, and ornamental plants.
Greenhouse Non-food Crops; Ornamental plants.
Domestic Outdoor Uses; Domestic dwellings, and
lawns.
Terrestrial Food Crop Use; Alfalfa (seed crop),
almonds, apples, apricots, beans, cherries,
chestnuts, corn (field), cotton, cucumbers,
eggplants, filberts, grapefruit, grapes, lemons,
limes, melons, nectarines, onions (dry & green),
oranges, peaches, peanuts, pears, pecans, peppers,
pimentos, plums, prunes, sorghum (grain & forage),
sorghum (seed crop), squash (summer),
strawberries, tangelos, tangerines, tomatoes, and
walnuts.
Mode of Insecticidal Activity: Toxic action is exerted by
inhibiting enzymes of the nervous
system through inhibition of
cholinesterase.
Method of Application: Ground and aerial foliar applications,
furrow treatments by ground equipment, and
seed treatment.
Annual Usage: 1.2 to 1.5 mi lion pounds of active ingredient are
used in the United States.
Predominant Usage: Citrus accounts for 86% to 89% of the total
pounds of ethion used in the United States.
The remaining 11% to 14% is applied to cotton
and a variety of fruit trees, nut trees, and
vegetables. Approximately 55% to 70% of all
domestically produced citrus fruits are
treated with ethion. Less than 2% of the
domestic cotton acreage and fewer than 10% of
the fruit (other than citrus), vegetable, and
nut acreage is treated with ethion.
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Formulations: Emulsifiable solution 500 g/1
Wettable Powder 25%
Dusts 2%,3%,and 4%
Emulsifiable concentrates 4 and 8 Ibs/gal
Granules 5% and 10%
3. Science Findings
Chemical Characteristics of Technical Material
Color: colorless to light brown or pale yellow.
Physical state: liquid at room temperature.
Odor: mild dithiophosphate
Melting point: -12°F to -15°F
Boiling point: 164-165°C at 0.3 mm Hg.
Specific gravity: 1.215-1.230 at 20°C
Solubility: Practically insoluble in water; soluble in most
organic solvents. •
Vapor pressure: 1.5 x 10~6mm Hg at 25°C
Dissociation constant: Not applicable; TGAI does not disperse in
water.
Octanol/water partition coefficient: 10,000 [GC with FPD
detector].
pH: 5.1 in an equal volume of distilled water.
Storage stability: 95% of-ethion remained unchanged during one
year of storage at 25°C. There was <2%
deterioration in three years of storage under
the same conditions. Recommended shelf 1'ife
is two years. Do not store below 20°F to
avoid crystal formation.
Corrosion: Ethion does not corrode stainless steel or aluminum.
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Summary Science Statement
Acute oral toxicity studies show that technical ethion is
highly toxic to mammals, particularly to females; [Toxicity
Category I (females) and Toxicity Category II (males)]. Ethion
has moderately high acute dermal and inhalation toxicities;
[Toxicity Category II for dermal toxicity and Toxicity Category
II (females) and Toxicity Category III (males) for acute
inhalation]. Ethion caused slight redness of the conjunctiva of
the eye and slight erythema on the skin. The effects cleared
within 48 hours, thus classifying ethion in Toxicity Category IV.
Ethion was not found to be a dermal sensitizer and does not cause
acute delayed neurotoxicity.
Subchronic toxicity; No compound-related histomorphologic changes
w^re found in a 90-Day Dog Feeding Study. Based upon the
inhibition of plasma cholinesterase activity observed, the LEL is
2.5 ppm and the NOEL is 0.5 ppm.
Chronic toxicity; In a chronic toxicity study conducted with
rats, a decrease in serum cholinesterase was observed in high
dose males and females. No other effects were observed. Based on
the cholinesterase inhibition, the systemic NOEL is 4 ppm and the
LEL is 40 ppm.
Oncogenicity; Ethion was not found to be carcinogenic in rats and
mice.
Teratogenicity: Studies conducted with rabbits and rats did not
indicate that there were any structural or functional
abnormalities in test animals. However, increases in the
incidence of hyperactivity of dams and delayed ossification of
pubes in fetuses were observed in the rat stiAy. In the rabbit
teratology study, there were increases in,the^incidence of
orange-colored urine, decreases in body weight and food
consumption, along with an increased incidence of fused sternal
centra in fetuses of treated females. The three generation
reproduction study did not show any compound related reproductive
effects, a decrease in serum cholinesterase activity.
Mutagenicity; Assays on gene mutation, structural chromosomal
aberration, and unscheduled DNA Synthesis indicate ethion is-not
mutagenic.
Reproduction and Fertility Effects; Ethion has a reproductive
NOEL of 25 ppm (HDT) and a systemic NOEL of 25 ppm for males and
4.0 ppm for females. These findings were based on tests in which
ethion was administered to groups of F0, Fj, F2, male and female
rats (15 males/dose and 30 females/dose) at dietary
concentrations of 0, 2, 4, and 25 ppm. A decrease in serum
cholinesterase activity was observed in the Fl, and F2 high-dose
females .(25 ppm).
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Gene mutation test; An Ames assay showed that ethion at the
concentration range of 0.625 to 10.0 nl/ml does not produce
mutagenic effects in five strains of Salmonella typhimurium (TA-
98, TA-100, TA-1535, TA-1537, and TA-1538).
Structural chromosome aberration test; An in vivo cytogenetic
assay indicated that ethion at dose ranges of 4.7 to 47 mg/kg
does not induce chromosome aberrations in rats.
Test for other aenotoxic effects; An unscheduled DNA synthesis
(USD) in rat primary hepatocytes showed no evidence of induction
of UDS at dose levels of 100, 500, 2500, 5,000, and 10,000
ug/plate.
Information on Human Effects;
A group of adult male volunteers (10) was randomly divided
into a control group (3 males) and a treatment group (6 males).
The treatment group received ethion serially and orally (gelatin
capsule) at dose levels of 0.05, 0.075, 0.1, and 0.15 mg/kg.
Significant reduction of plasma cholinesterase activity was seen
at doses of 0.075 mg/kg and above. Based upon this data a NOEL of
0.05 mg/kg and a LED of 0.075 mg/kg/day were established.
Environmental Characteristics
Environmental Fate; The Agency has determined that ethion appears
to be resistant to hydrolysis (except at very alkaline pH),
photolyzes in water and on soil (half-life of 58 and 51 days
respectively), and its major metabolite is C02.
Groundwater; The Agency presently be Li eves that ethion is not
expected to leech. Available data in^date that it is immobile
and only moderately persistent.
Ecological Characteristics
Aquatic Toxicitv; Technical ethion is very highly toxic to
freshwater and marine fish.. Acute toxicity ranges from an LC50 of
49 ppb for Bluegill to an LC50 of 720 ppb for Cutthroat trout and
flathead minnows.
Ethion appears to be a heavy bioaccumulator (1400 for whole
fish on day 42).
Ethion is very highly toxic to freshwater invertebrates. The
acute toxicity ranged from 0.056 to 7.7 ppb. The toxicity of
ethion to marine/estuarine invertebrates is also very high,
ranging from 5.6 ppb to 49 ppb.
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Honeybee Acute Toxicity; Ethion was found to be practically non-
toxic to honeybees (LD50 20.55 ug/bee).
Endangered Species; Because of the demonstrated toxicity of
ethion to nontarget fish and aquatic invertebrates, ethion has
been identified by the Office of Endangered Species (OES), U.S.
Fish and Wildlife Service (FWS) as being likely to negatively
impact on endangered aquatic organisms when applied to certain
crops (i.e. citrus, corn, sorghum and cotton). The Agency is
developing a program to reduce or eliminate exposure to these
vulnerable organisms, and will issue notice of any product
labeling, other than those identified in this registration
standard, when the program has been developed and implemented.
Worker Protection
Based on the acute hazard to exposed persons, the following
interim reentry intervals will be imposed until appropriate
exposure data has been evaluated by the Agency:
Crop Reentry interval from last application
Citrus 30 Days
Peaches 14 Days
Nectarines 14 Days
Grapes 14 Days
All other crops 2 Days
The precautionary and protective clothing label statements
listed below are required on all products containing ethion with
the signal words DANGER or WARNING that are applied to
agricultural sites, structural pest .control sites, or
greenhouses.
"Do not rub eyes or mouth with hands. If you feel sick in any way
STOP work and get help right away. See Practical Treatment
Section of this label."
"Do not apply this product in a way that will contact unprotected
workers, either directly or though drift. Only protected handlers
may be in the area during application."
"USE ONLY WHEN WEARING THE FOLLOWING PROTECTIVE CLOTHING AND
EQUIPMENT-DURING MIXING/LOADING, APPLICATION, REPAIR AND CLEANING
OF MIXING, LOADING, AND APPLICATION EQUIPMENT, DISPOSAL OF THE
PESTICIDE, AND EARLY REENTRY INTO TREATED AREAS: Protective suit
of one or two pieces covering all parts of the body except head,
hands, and feet; chemical resistant gloves; chemical resistant
shoes (or chemical resistant shoe covers or chemical resistant
boots) ; and a NIOSH or MSA approved respirator. In addition,
mixer/loaders must wear a chemical resistant apron and face
shield or goggles.
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During equipment repair and cleaning, the respirator need not be
worn. During early reentry after sprays have dried or dusts have
settled and vapors have dispersed, the respirator need not be
worn.
IF MIXING/LOADING IS PERFORMED USING A CLOSED SYSTEM, THE
FOLLOWING PROTECTIVE CLOTHING AND EQUIPMENT MAY BE WORN AS AN
ALTERNATIVE: long-sleeved shirt and longlegged pants; shoes and
socks. Chemical resistant gloves must be available in the cab or
cockpit and must be worn when exiting. This clothing is
inadequate protection during equipment repair or cleaning,
reentry, or pesticide disposal work.
IMPORTANT! If pesticide comes in contact with skin, immediately
wash off with soap and water. Always wash hands, face, and arms
with soap and water before smoking, eating, drinking, or when
using the toilet.
AFTER WORK: Wash gloves with soap and water before removing them.
Take off all work cloths and shoes. After removing clothing
shower using soap and water, then put on clean clothes. Do not
reuse contaminated clothing. Personal clothing worn during work
must be .laundered separately from household items. Store
protective clothing separate from personal clothing. Clean or
launder protective clothing after each use. Respirators must be
cleaned and filters replaced according to instructions included
with the respirator. Protective clothing and equipment that
becomes heavily contaminated or drenched must be destroyed
according to state and local regulations. HEAVILY CONTAMINATED OR
DRENCHED CLOTHING CANNOT BE ADEQUATELY DECONTAMINATED.
DURING AERIAL APPLICATION, HUMAN FLAGGERS MUST BE IN A TOTALLY
ENCLOSED VEHICLE."
"Do not enter or allow entry into treated areas until
(sprays have dried/dusts have settled/vapors have dispersed, as
applicable) to perform hand labor tasks. A person may enter the
area to perform other tasks only if the person is wearing the
personal protective clothing listed on the label."
"After (sprays have dried/dusts have, settled/vapors
dispersed, as applicable) do not enter or allow entry into the
treated area until the reentry interval has expired, unless the
person entering the treated area is wearing the personal
protective equipment listed on the label for early reentry."
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Tolerance Assessment
Tolerances for ethion in or"' on raw agricultural commodities
and animal products are published in 40 CFR 180.173. Food
additive tolerances for ethion have been established for dried
tea and raisins and are published in 40 GFR 185.2750 (formerly 21
CFR 193.190). A feed additive tolerance for ethion has been
established for dehydrated citrus pulp and is published in 40 CFR
186.2750 (formerly 21 CFR 561.23.0). All tolerances are expressed
in terms of ethion and its oxygen analog (s-
[[diethoxyphosphinothioyl)thio)methyl]0,0-
diethylphosphorothioate].
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Summary of Tolerances Issued for Ethion
Tolerances (PPM)
MRL
Commodities
Almonds
Almond, hulls
Apples
Apricots
Beans
Cattle, fat
Cattle, meat
Cattle, mbyp
Cherries
Chestnuts
Citrus
Citrus, pulp
Corn, fodder
Corn, forage
Corn, grain
Cottonseed
Cucumbers
Eggs
Eggplants
Filberts
Goats , fat
Goats , meat
Goats , mbyp
Grapes
Raisins
Hogs , fat
Hogs , meat
Hogs , mbyp
Horses , fat
Horses , meat
Horses , mbyp
Melons
Milk, fat
Nectarines
Onions
Peaches
Pears
Pecans
Peppers
Pimentos
Plums (fresh prunes
Poultry, fat
Poultry, meat
US
=,'
0.1
5.0
2.0
0.1
2.0
2.5
2.5
1.0
0.1
0.1
2.0
10
14
14
0.1 iy
0.5 '"
0.5 -
0.2
1.0
0.1
0.2
0.2
0.2
2.0
4.0
0 . 2 :
0.2 .-,-.
0.2
0.2
0.2
0.2
2.0 ::.,--
0.5
1.0
1.0
1.0
2.0
0.1
1.0 ,
1.0
)2.0
0.2
0.2
International
Canadian
0.1
2
none
1
2.5
2.5
2.5
none
none
2
none
none
none
none
0.1
none
0.1
none
none
none
none
2
none
none
none
none
none
none
0.1
none
none
0.1
1.0
2
none
0.1
' 0.1
1.0
none
none
Mexican
0.1
2
none
2
none
none
none
none
0.1
2
none
14
0.1
0.5
0.5
none
1
0.1
none
none
none
2
none
none
none
none
none
none
2
none
none
1
1.0
1
0.1
1 •-.
none
none
none
Codex
O.I1
21
O.I1
none2
2.51
I1
O.I1
O.I1
21
none2
none2
0.053
0.51
0.51
0.21
I1
O.I1
0.21
0.21
0.21
21
0.21
0.21
0.21
0.21
0.21
0.21
21
0.24
l.O1
I1
l.O1
21
O.I1
I1
none2
2.01
0.21
0.21
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Summary of Tolerances Issued for Ethion
Commodities
Poultry, mbyp
Sheep , fat
Sheep , meat
Sheep , mbyp
Sorghum, forage
Sorghum, grain
Squash , summer
Strawberries
Tea (dried)
Tomatoes
Walnuts
US
0.2
0.2
0.2
0.2
2.0
2.0
0.5
2.0
10.0
2.0
0.1
Tolerances (PPM)
MRL
International
Canadian
none
none
none
none
none
none
0.1
1.0
none
0.5
none
Mexican
none
none
none
none
2.0
2.0
0.5
2.0
none
2
O.l
Codex
0.21
0.21
0.21
0.21
none2
none2
0.51
2.01
5.05
21
O.I1
1. Established Codex MRL is numerically identical to U.S.
Tolerance.
2. No Codex MRL has been established, therefore, no questions of
compatibility exist with respect to Codex MRL.
3. A Codex MRL (CXL) of 0.055 ppm exist for residues of ethion
per se in or on maize. This level is lower than that of the
U.S. .
4. U.S. Tolerance is higher.
5. (Careen, black tea): A decision regarding the potential for
c^ipatibility between the permanent Codex MRL and the U.S.
tolerance will not be made until the adequacy of the U.S. .
tolerance has been ascertained.
Summary of Dietary Exposure Analysis
The Agency has concluded that the use of ethion will not
result in chronic health effects. There does not appear to be a
health risk from short term exposure to ethion residue on
grapefruit, stone fruits other than peaches and plums, eggs,
grains, meat nuts, and poultry. However, based on-the limited
data'/information available, short term exposure to ethion from
residues on peaches, vegetables, tea, and oranges may result in
acute cholinesterase inhibition for selected TAS populations,
infants and children. Also, short term exposure to ethion
residues on apples and pears, grapes, melons, tomatoes dry beans,
succulent beans, strawberries (pooled with citrus other than
oranges and grapefruit), and plums or prunes may result in acute
cholinesterase inhibition in all TAS population groups.
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The Agency is initiating a Data Call-in to exaimine acute
dietary exposure; anticipated residue data are being called in
under 40 CFR 158.240 (Reduction of Residue).
SUMMARY OF REGULATORY POSITION
' The Agency is considering further regulatory action based on
dietary exposure concerns. The Agency has determined that
certain current tolerances may not provide an adequate margin
of safety in humans. Short term exposure to ethion residues on
apples and pears, grapes, melons, tomatoes, dry beans,
succulent beans, strawberries (pooled with citrus other than
oranges and grapefruit), and plums and prunes may result in
acute cholinesterase inhibition for all TAS population groups.
The Agency also has determined that short term exposure to
ethion residues on peaches, vegetables, tea, and oranges may
result in acute cholinesterase inhibition in selected TAS
populations, infants and children.
' The Agency is not imposing the Restricted Use Classification on
all pesticide products containing ethion. At present three
ethion products are classified Restricted Use because of their
high dermal and inhalation toxicity. Two of these products
contain 81.9% active ingredient and the other 81% active
ingredient. The Agency will make a decision regarding the
Restricted Use Classification on a product-by-product basis for
the remaining products after evaluating the product specific
toxicity data submitted in response to the Registration
Standard issued September 30, 1989.
No groundwater advisory labeling is required because ethion is
not expected to leach.
' Based on the high acute toxicity and worker poisoning
incidents, the Agency is requiring label language stipulating
the use of protective clothing and the following reentry
intervals.
Citrus 30 Days
Nectarines 14 Days
Peaches 14 Days
Grapes. . . .- . 14 Days
All other crops and uses. 2 Days
The Agency is imposing these reentry intervals as an interim
measure until reentry data can be generated.
No significant new food uses or increases of tolerances for
food or feed items treated with ethion will be considered
until the outstanding residue chemistry studies and residue
reduction information have been submitted and reviewed by the
Agency.
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CONTACT PERSON AT EPA;
Product Specific Inquiries:
William Miller
Product Manager (Team 16) .,
Insecticide-Rodenticide Branch
Registration Division (H7505C)
Office of Pesticide Programs, EPA
Environmental Protection Agency
401 M Street, S. w.
Washington, DC 20460
Office location and telephone number:
Room 211, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202
(703) 557-2600
Reregistration Document Inquiries:
Richard W. King
Review Manager ;
Reregistration Branch *
Special Review and Reregistration
Division (H-7508C)
Environmental Protection Agency
401 M Street, S.W.
Washington. D.C. 20460
Office location and telephone number:
Room 1120 Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202 ;
(703) 557-0304
DTsrr.ATMF.T?; The information in this Pesticide Fact- Sheet is a
summary only and is not to be used to satisfy data
requirements for pesticide registration and
reregistration. The complete Reregistration
Document for the pesticide may be obtained from
the National Technical Information Service.
Contact the Review Manager listed above for
further information.
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