United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-95-004
April 1995
R.E.D. FACTS
Ethephon
Pesticide
Re registration
All pesticides sold or distributed in the United States must be
registered by EPA, based on scientific studies showing that they can be used
without posing unreasonable risks to people or the environment. Because of
advances in scientific knowledge, the law requires that pesticides which
were first registered years ago be reregistered to ensure that they meet
today's more stringent standards.
In evaluating pesticides for reregistration, EPA obtains and reviews a
complete set of studies from pesticide producers, describing the human
health and environmental effects of each pesticide. The Agency imposes
any regulatory controls that are needed to effectively manage each
pesticide's risks. EPA then reregisters pesticides that can be used without
posing unreasonable risks to human health or the environment.
When a pesticide is eligible for reregistration, EPA announces this and
explains why in a Reregistration Eligibility Decision (RED) document. This
fact sheet summarizes the information in the RED document for
reregistration case 0382, Ethephon.
Ethephon is a plant growth regulator used to promote fruit ripening,
abscission, flower induction, and other responses. Ethephon is registered
for use on a number of food, feed and nonfood crops, greenhouse nursery
stock, and outdoor residential ornamental plants, but is used primarily on
cotton. Formulations include formulation intermediates and soluble
concentrates/liquids. Ethephon is applied to plant foliage by either ground
or aerial equipment. It also may be applied by hand sprayer to certain home
garden vegetables and ornamentals.
Use practice limitations include prohibitions against applying ethephon
through any type of irrigation system; feeding or grazing livestock in treated
areas; and treating within 2 to 60 days of harvest, depending on the crop.
Regulatory Ethephon was discovered in 1965, and was first registered as a
History pesticide in the U.S. in 1973. EPA issued a Registration Standard for
ethephon in September 1988 (PB89-109427), requiring toxicology, residue
chemistry, and environmental fate and effects data.
Use Profile
-------
Human Health Toxicity
AsS6SSm6nt Ethephon is corrosive in acute dermal irritation studies using rabbits,
has the potential to cause eye irritation, and has been placed in Toxicity
Category I (the highest of four categories) for these effects. It is moderately
acutely toxic by the oral, dermal and inhalation routes (Toxicity Category
III), and does not cause skin sensitization.
An organophosphate pesticide, ethephon caused plasma cholinesterase
inhibition in a 16-day oral human study and clinical signs of toxicity in a
second study. In a dermal toxicity study using rabbits, skin effects were
observed at all doses.
In a combined chronic/oncogenicity study using rats, plasma and
erythrocyte cholinesterase were inhibited at all doses. At the highest dose
levels, ethephon caused body weight decrease and kidney effects, but no
carcinogenic effects were observed. In a cancer study using mice, no
evidence of treatment related tumors was observed. Ethephon has been
classified as a Group D carcinogen based on "the insufficiency of the weight
of evidence" regarding its cancer-causing potential.
One chronic toxicity study using beagle dogs caused plasma
cholinesterase inhibition at all doses, and smooth muscle atrophy in the gut.
In a second beagle dog study, treatment related effects included decreased
spleen and body weight plus decreased hemoglobin and hematocrit in the
males.
Developmental toxicity studies using rats and rabbits show no
evidence of a potential for developmental effects at doses that are not toxic
to the mother. In a reproductive toxicity study using rats, administration of
the test compound caused decreased survival in the offspring and decreased
body weight gain in adult females, but no effects on fertility, gestation,
mating, organ weights, or histopathology in any generation.
Ethephon was positive in one mutagenicity study and negative in two
others. It does not appear to cause delayed neurotoxicity based on a study
using hens, however studies using mammals are now required as
confirmatory data.
Human poisoning incidents involving ethephon include four cases of
skin injury (irritation) in California as a result of exposure to field residues,
one possible systemic poisoning case, and 29 telephone calls to the National
Pesticides Telecommunications Network reporting eye and skin irritation
from misuse of ethephon, sometimes in combination with other pesticides.
Dietary Exposure
People may be exposed to residues of ethephon through the diet.
Tolerances or maximum residue limits have been established for ethephon in
many raw agricultural commodities, processed foods, and feed. Please see
40 CFR 180.300(a) and (b), 185.2700(a), (b) and (c), and 186.2700(a).
-------
Several additional tolerances, including food and feed additive tolerances,
have been proposed.
Sufficient data are available to assess the adequacy of most established
ethephon tolerances, although some require additional residue chemistry or
animal feeding studies. Some changes are needed; certain tolerances must
be revoked because registrations for these crop uses no longer exist, and a
tolerance for cottonseed must be increased. Several new tolerances may
need to be established.
EPA has assessed the chronic dietary risk posed by ethephon,
evaluating exposure and risk, first, from all uses for which tolerances exist,
have been recommended or have been proposed and, second, excluding uses
for which revocation is recommended. For the overall U.S. population and
22 subgroups, the Anticipated Residue Contribution (ARC) from all current
and proposed ethephon tolerances represents 9% of the Reference Dose
(RfD), an amount believed not to cause adverse effects if consumed daily
over a 70-year lifetime. The ARC of the most highly exposed subgroup,
non-nursing infants less than one year old, represents 49% of the RfD.
Excluding the tolerances recommended for revocation, the ARC for the
overall U.S. population represents 8.6% of the RfD, while the ARC for
non-nursing infants represents 47% of the RfD. Therefore, it appears that
chronic dietary risk is not of concern.
Because ethephon causes neurotoxic effects (cholinesterase inhibition),
an acute dietary exposure analysis also was conducted. Margins of
Exposure (MOEs), which show how closely estimated exposure comes to a
dose of concern, were calculated for several population subgroups. Infants
less than one year old are the only subgroup whose exposure may be of
concern, with 5% of the population estimated to have MOEs of less than 7
(an MOE of 10 or greater is desirable). However, these risk values
represent an unrealistic worst case situation. Many conservative
assumptions were included in calculating these risks, such as: all registered
food crops are treated; maximum residue levels are present on all foods; and
no dilution or degradation of residues has occurred during preparation or
processing of food. EPA believes it is unlikely that infants and children will
be exposed to ethephon-treated commodities at levels that will result in acute
dietary risk.
Several international Codex Maximum Residue Limits (MRLs) have
been established for ethephon. Compatibility between U.S. tolerances and
Codex MRLs exists for apples, blackberries, cherries, pineapples and
walnuts, and may be achieved for tomatoes by raising the U.S. tolerance.
For other crops, the U.S. tolerances are being revoked or additional field
residue data are needed.
-------
Environmental
Assessment
Occupational and Residential Exposure
Based on current use patterns, workers may be exposed to ethephon in
agricultural and other settings, during and after applications using open
pouring methods and broadcast (aerial and ground) treatment or hand-held
spray equipment. Ethephon does not pose risks of systemic dermal or
inhalation toxicity. However, since it does pose risks of severe skin and eye
irritation (Toxicity Category I), certain Worker Protection Standard (WPS)
provisions apply.
To protect post-application workers, a 48-hour restricted entry interval
(REI) imposed by the WPS is being retained. This interval must be
increased to 72 hours when ethephon is applied outdoors in arid areas.
Certain personal protective equipment (PPE), including protective eyewear,
is required for early entry into treated areas. In addition, since ethephon is
in Toxicity Category I for primary skin irritation, "double notification" is
required: agricultural workers must be warned orally of its application, and
WPS warning signs must be posted at entrances to treated areas.
Human Risk Assessment
Ethephon has the potential to cause severe skin and eye irritation
(Toxicity Category I), but otherwise is moderately acutely toxic. An
organophosphate pesticide, it has the potential to cause cholinesterase
inhibition. Ethephon is classified as a "Group D" carcinogen because there
is insufficient weight of evidence regarding its cancer-causing potential.
Ethephon is used on many food and feed crops. Its tolerances have
been reassessed, and while they generally are acceptable, some changes are
required. EPA's dietary risk assessments indicate that infants less than one
year old encounter the greatest exposure and risk as a result of ethephon
crop use. However, since the Agency used many conservative assumptions
in calculating these risks, actual dietary exposure and risk to infants as well
as the overall U.S. population are believed to be minimal.
Pesticide handlers may be exposed to ethephon during application, and
post-application workers may be exposed to residues on treated crops. To
reduce workers' skin and eye irritation risks, a 48-hour REI is being
retained and is increased to 72 hours in arid areas, use of certain PPE
including protective eyewear is required for early entry, and double
notification of workers is required.
Environmental Fate
Ethephon is not persistent in the environment. The major routes of
dissipation appear to be chemical hydrolysis and microbial degradation.
Although ethephon degrades in somewhat acidic soils (pH 6.1), it does not
hydrolyze in sterile, acidic water (pH 5). The major degradates are
ethylene gas and 2-hydroxy ethyl phosphonic acid. Ethephon has moderate
to low mobility in soil. It has a very low octanol/water partition coefficient
and, therefore, is not expected to accumulate in fish.
-------
Additional Data
Required
In the field, ethephon exhibits the same characteristics of rapid
degradation and moderate to low mobility as seen in the laboratory. At field
sites in southern California, North Carolina, and Washington, ethephon
dissipated with half-lives of about 7 to 25 days.
Ecological Effects
In dietary studies using the bobwhite quail and mallard duck, ethephon
is practically nontoxic to slightly toxic on an acute basis, and practically
nontoxic on a subacute basis. Acute oral studies using rats show that
ethephon is slightly toxic to mammals. Other acute toxicity studies show
that ethephon is practically nontoxic to coldwater fish, and practically
nontoxic to slightly toxic to warmwater fish and freshwater invertebrates.
Ethephon is practically nontoxic to shrimp, and slightly toxic to
estuarine/marine mollusks. It is relatively nontoxic to honeybees.
Regarding effects on terrestrial plants, ethephon reduces plant growth,
resulting in reduced shoot lengths and weights.
Ecological Effects Risk Assessment
Ethephon is expected to have minimal effects on birds and mammals,
as well as on fish, freshwater invertebrates, and marine and estuarine
organisms.
Although minimal effects to aquatic and terrestrial plants (dry land)
are expected, ethephon may pose a risk to semi-aquatic/wetland plants
(including endangered semi-aquatic plants) when it is used on apples in
North Carolina, cotton, tobacco, macadamia nuts, blackberries and
pineapple. However, ethephon is a growth regulator and as such is not
intended to be toxic to plants. Also, the magnitude of this risk is not high.
Therefore, while the potential for risk to semi-aquatic plants exists, it is not
extensive, arises only infrequently during periods of high exposure, and is
geographically limited.
In response to Agency concerns about ethephon's risk to semi-aquatic
plants, the registrant proposed as a risk mitigation measure to reduce the
maximum use rate for blackberries and apples in North Carolina to 2.0
pounds per acre. They also provided information indicating that ethephon is
used only occasionally at maximum rates when certain weather conditions
exist, such as cool temperatures. Considering these factors, EPA believes
that the risk to nontarget plants from use of ethephon will be limited.
EPA is requiring the following additional generic data for ethephon to
confirm its regulatory assessments and conclusions: Product chemistry;
Animal metabolism (poultry); Residue analytical method in plants and
animals; Storage stability; Magnitude of the residue in plants (peppers,
cantaloupes, grapes, wheat forage and hay, and cotton gin byproducts);
Magnitude of the residue in processed sugarcane; Magnitude of the residue
in poultry and ruminant; Batch equilibrium on the degradate of 2-hydroxy
ethyl phosphonic acid; Acute and subchronic neurotoxicity.
-------
Product Labeling
Changes
Required
The Agency also is requiring product-specific data including product
chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs) and revised labeling for reregistration.
All ethephon end-use products must comply with EPA's current
pesticide product labeling requirements, and with the following:
Worker Protection
Personal Protective Equipment (PPE) for Handlers
PPE for handlers will be based on the toxicity of each end-use product
(see PR Notice 93-7). If PPE is necessary for homeowner uses, it will be
established during end-use product reregistration.
Entry Restrictions for Occupational-Use Products:
Worker Protection Standard (WPS) Uses
EPA is establishing a 48-hour restricted entry interval (REI), which
increases to 72 hours in outdoor areas where average rainfall is less than 25
inches a year. PPE for WPS-permitted early entry into treated areas is
coveralls over long-sleeved shirt and long pants, chemical-resistant gloves
such as any waterproof gloves, chemical-resistant footwear plus socks, and
chemical-resistant headgear for overhead exposures. In addition, protective
eyewear is required since ethephon is in Toxicity Category I for eye
irritation potential.
Non-WPS Uses
Products with uses outside the scope of the WPS must bear the
following statement:
"Do not allow people or pets to touch treated plants until the sprays
have dried."
Entry Restrictions for Homeowner-Use Products
Ethephon products with directions for use by homeowners must bear
the following statement:
"Do not allow people or pets to touch treated plants until the sprays
have dried."
Other Labeling Requirements
Reduce PPE when Engineering Controls are Used
"When handlers use closed systems, enclosed cabs, or aircraft in a
manner that meets the requirements listed in the WPS [40 CFR
170.240(d)(4-6)], the handler PPE requirements may be reduced or
modified as specified in the WPS."
User Safety Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE. If
no such instructions exist for washables, use detergent and hot water.
Keep and wash PPE separately from other laundry."
-------
"Discard clothing and other absorbent materials that have been
drenched or heavily contaminated with this product's concentrate. Do
not reuse them."
User Safety Statements
"Users should wash hands before eating, drinking, chewing gum,
using tobacco, or using the toilet."
"Users should remove clothing immediately if pesticide gets inside."
"Users should remove PPE immediately after handling this product.
As soon as possible, wash thoroughly and change into clean clothing.
Wash the outside of gloves before removing."
Application Restrictions
"Do not apply this product in a way that will contact workers or other
persons, either directly or through drift. Only protected handlers may
be in the area during application."
Notification
"Notify workers of the application by warning them orally and by
posting warning signs at entrances to treated areas."
Environmental Hazard
The following precautionary statement is required to address risks to
wetlands:
"Do not apply directly to water, or to areas where surface water is
present, or to intertidal areas below the mean high water mark."
For residential use sites (ornamental trees, shrubs, vines and herbaceous
plants), the statement, "Do not apply directly to water" may be used instead
of the statement above.
Spray Drift
The following language is required on each product label that can be
applied aerially:
"AVOIDING SPRAY DRIFT AT THE APPLICATION SITE IS
THE RESPONSIBILITY OF THE APPLICATOR."
"The interaction of many equipment-and-weather-related factors
determine the potential for spray drift. The applicator is responsible
for considering all these factors when making decisions."
"The following drift management requirements must be followed to
avoid off-target movement from aerial applications to agricultural field
crops. These requirements do not apply to forestry applications,
public health uses or to applications using dry formulations."
" 1. The distance of the outer most nozzles on the boom must not
exceed 3/4 the length of the wingspan or rotor."
"2. Nozzles must always point backward parallel with the air stream
and never be pointed downwards more than 45 degrees."
-------
"Where states have more stringent regulations, they should be
observed."
"The applicator should be familiar with and take into account the
information covered in the Aerial Drift Reduction Advisory
Information."
The following Aerial Drift Reduction Advisory Information must be
contained in the product labeling:
" [This section is advisory in nature and does not supersede the
mandatory label requirements]."
Information on Droplet Size
"The most effective way to reduce drift potential is to apply large
droplets. The best drift management strategy is to apply the largest
droplets that provide sufficient coverage and control. Applying larger
droplets reduces drift potential, but will not prevent drift if
applications are made improperly, or under unfavorable environmental
conditions (See Wind, Temperature and Humidity, and Temperature
Inversions)."
Controlling Droplet Size
o "Volume - Use high flow rate nozzles to apply the highest
practical spray volume. Nozzles with higher rated flows
produce larger droplets."
o "Pressure - Do not exceed the nozzle manufacturer's
recommended pressures. For many nozzle types lower pressure
produces larger droplets. When higher flow rates are needed,
use higher flow rate nozzles instead of increasing pressure."
o "Number of nozzles - Use the minimum number of nozzles that
provide uniform coverage."
o "Nozzle Orientation - Orienting nozzles so that the spray is
released parallel to the airstream produces larger droplets than
other orientations and is the recommended practice. Significant
deflection from horizontal will reduce droplet size and increase
drift potential."
o " Nozzle Type - Use a nozzle type that is designed for the
intended application. With most nozzle types, narrower spray
angles produce larger droplets. Consider using low- drift
nozzles. Solid stream nozzles oriented straight back produce the
largest droplets and the lowest drift."
Boom Length
"For some use patterns, reducing the effective boom length to less
than 3/4 of the wingspan or rotor length may further reduce drift
without reducing swath width."
Application Height
-------
"Applications should not be made at a height greater than 10 feet
above the top of the target plants unless a greater height is required
for aircraft safety. Making applications at the lowest height that is
safe reduces exposure of droplets to evaporation and wind."
Swath Adjustment
"When applications are made with a crosswind, the swath will be
displaced downwind. Therefore, on the up and downwind edges of
the field, the applicator should compensate for this displacement by
adjusting the path of the aircraft upwind. Swath adjustment distance
should increase, with increasing drift potential (higher wind, smaller
drops, etc.)."
Wind
"Drift potential is lowest between winds speeds of 2 - 10 mph.
However, many factors, including droplet size and equipment type
determine drift potential at any given speed. Application should be
avoided below 2 mph due to variable wind direction and high
inversion potential. NOTE: Local terrain can influence wind
patterns. Every applicator should be familiar with local wind patterns
and how they affect spray drift."
Temperature and Humidity
"When making applications in low relative humidity, set up equipment
to produce larger droplets to compensate for evaporation. Droplet
evaporation is most severe when conditions are both hot and dry."
Temperature Inversions
"Applications should not occur during a temperature inversion because
drift potential is high. Temperature inversions restrict vertical air
mixing, which causes small suspended droplets to remain in a
concentrated cloud. This cloud can move in unpredictable directions
due to the light variable winds common during inversions.
Temperature inversions are characterized by increasing temperatures
with altitude and are common on nights with limited cloud cover and
light to no wind. They begin to form as the sun sets and often
continue into the morning. Their presence can be indicated by ground
fog; however, if fog is not present, inversions can also be identified
by the movement of smoke from a ground source or an aircraft smoke
generator. Smoke that layers and moves laterally in a concentrated
cloud ( under low wind conditions) indicates an inversion, while
smoke that moves upward and rapidly dissipates indicates good
vertical air mixing."
Sensitive Areas
"The pesticide should only be applied when the potential for drift to
adjacent sensitive areas (e.g. residential areas, bodies of water, known
habitat for threatened or endangered species, non-target crops) is
minimal (e.g, when wind is blowing away from the sensitive areas)."
-------
Residue Chemistry
The following label revisions must be added to pertinent end-use
products:
° Product labels must be amended to reflect a maximum allowable
use rate of 2 Ib ai/A/season for application of ethephon to cotton.
° Label directions for apples, cranberries, carob, and olives that are
for ornamental use only must be clearly designated as such.
° The 0.33 Ib/gal SC/L label (264-263) must be amended to prohibit
the harvesting of any treated pumpkins for human or animal
consumption and must specify that treatments are to be made to
pumpkins for seed production only.
° Labels must be amended to reduce the maximum use rate for
blackberries and apples in N.C. to 2.0 Ib per acre.
A table near the end of the RED document identifies the Food/Feed
Use Patterns Subject to Reregistration for Ethephon. This table lists
currently acceptable use sites, formulations, application rates, methods and
equipment, pre-harvest and reentry intervals, and use limitations for
ethephon products registered by the basic manufacturer. All ethephon end-
use product labels must be amended to be consistent with the basic producer
labels, as reflected in this table.
Regulatory
Conclusion
For More
Information
The use of currently registered products containing ethephon in
accordance with approved labeling will not pose unreasonable risks or
adverse effects to humans or the environment. Therefore, all uses of these
products are eligible for reregistration.
Ethephon products will be reregistered once the required product-
specific data, revised Confidential Statements of Formula, and revised
labeling are received and accepted by EPA.
EPA is requesting public comments on the Reregistration Eligibility
Decision (RED) document for ethephon during a 60-day time period, as
announced in a Notice of Availability published in the Federal Register. To
obtain a copy of the RED document or to submit written comments, please
contact the Pesticide Docket, Public Response and Program Resources
Branch, Field Operations Division (7506C), Office of Pesticide Programs
(OPP), US EPA, Washington, DC 20460, telephone 703-305-5805.
Electronic copies of the RED and this fact sheet can be downloaded
from the Pesticide Special Review and Reregistration Information System at
703-308-7224. They also can be reached on the Internet via
FEDWORLD.GOV, or obtained from EPA's gopher server,
EARTH1.EPA.GOV.
10
-------
Printed copies of the RED and fact sheet can be obtained from EPA's
National Center for Environmental Publications and Information
(EPA/NCEPI), PO Box 42419, Cincinnati, OH 45242-0419, telephone
513-489-8190, fax 513-489-8695.
Following the comment period, the ethephon RED document also will
be available from the National Technical Information Service (NTIS), 5285
Port Royal Road, Springfield, VA 22161, telephone 703-487-4650.
For more information about EPA's pesticide reregistration program,
the ethephon RED, or reregistration of individual products containing
ethephon, please contact the Special Review and Reregistration Division
(7508W), OPP, US EPA, Washington, DC 20460, telephone
703-308-8000.
For information about the health effects of pesticides, or for assistance
in recognizing and managing pesticide poisoning symptoms, please contact
the National Pesticides Telecommunications Network (NPTN). Call toll-
free 1-800-858-7378, between 8:00 am and 6:00 pm Central Time, Monday
through Friday.
11
------- |