United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-94-021
September 1994
R.E.D. FACTS
Pesticide
Reregistration
Fenbutatin-oxide
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 reregi strati on, 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 reregi strati on, EPA announces this
and explains why in a Reregi strati on Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 0245, fenbutatin-oxide or Vendex.
Use Profile
Fenbutatin-oxide is a miticide or acaricide used to control mites,
aphids, thrips, mealybugs, whiteflies and scale on citrus, apples, stone
fruits, nut trees, several other food crops and ornamentals. Marketed under
the trade name Vendex, fenbutatin-oxide is used in the U.S. primarily on
orange and grapefruit crops.
Fenbutatin-oxide is formulated as a wettable powder, emulsifiable
concentrate and soluble concentrate. It is applied aerially or through
airblast or groundboom equipment two to nine times per year, depending
on the site.
Regulatory
History
Fenbutatin-oxide was first registered as a pesticide in the U.S. in
1974. The first end-use product was registered in August 1975. EPA
issued a Registration Standard for fenbutatin-oxide in March 1987 (NTIS
#PB87-190690). Currently, 10 pesticide products containing this active
ingredient are registered.
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Human Health
Assessment
Toxicity
Fenbutatin-oxide generally is of low acute toxicity. However, it is a
severe eye irritant in rabbits and has been placed in Toxicity Category I,
indicating the highest degree of acute toxicity, for eye irritation effects.
In a subchronic dermal toxicity study using rabbits, fenbutatin-oxide
caused redness of the skin and swelling at a low dosage but did not cause
systemic toxicity.
Fenbutatin-oxide does not cause chronic toxicity and has been
classified as a "Group E" carcinogen—a chemical showing evidence of non-
carcinogenicity for humans.
In a developmental toxicity study using rats, fenbutatin-oxide caused
no compound-related effects in treated dams. A similar study using rabbits
resulted in anorexia, gastric lesions and abortions. In a reproductive
toxicity study using rats, decreased body weight and food consumption
were observed in parents, and pup body weights also were reduced during
lactation. Fenbutatin-oxide is not mutagenic.
Metabolism studies indicate that the potential for bioaccumulation of
fenbutatin-oxide is minimal. Approximately 1% of the pesticide is
absorbed from the gastrointestinal tract when it is administered orally.
A reference dose (RfD), or amount believed not to cause adverse
effects if consumed daily over a 70-year lifetime, has been established for
fenbutatin-oxide at 0.05 mg/kg/day (milligrams per kilogram per day).
This RfD is based on the reproductive toxicity study which caused reduced
body weight and food consumption in both generations of rats.
Dietary Exposure
People may be exposed to residues of fenbutatin-oxide through the
diet. Tolerances or maximum residue limits have been established for
citrus, apples, many stone and other fruits, tree nuts and several vegetables
(please see 40 CFR 180.362(a) and (c)); for milk fat, eggs and the meat, fat
and meat byproducts of cattle, goats, hogs, horses, poultry and sheep
(please see 40 CFR 180.362(b); for dried prunes and raisins (please see 40
CFR 185.3550); and for apple and grape pommace, citrus oil and pulp, and
raisin waste (please see 40 CFR 186.3550). EPA has reassessed these
fenbutatin-oxide tolerances and found that a number of changes are
needed, as detailed in the RED document.
International maximum residue limits (MRLs) have been established
by Codex for many food commodities. However, because of the
differences in tolerance expression between the MRLs and U.S tolerances,
compatibility between the two is not achievable. In addition, the U.S.
tolerances are higher than the corresponding Codex MRLs. Established
U.S. agricultural practices for application of fenbutatin-oxide are unlikely
to be changed. Therefore, U.S. tolerance levels probably cannot be
lowered to achieve compatibility with Codex MRLs.
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EPA has assessed the dietary risk posed by fenbutatin-oxide. For the
overall U.S. population, exposure from all current tolerances represents
136% of the Reference Dose (RfD), or amount believed not to cause
adverse effects if consumed daily over a 70-year lifetime. This value
likely overstates the risk, however, because it assumes all crops have
tolerance-level residues and 100% of all crops with tolerances are treated.
Information on actual anticipated residue levels and percent of crop
treated with fenbutatin-oxide was included to more accurately estimate
dietary exposure. The resulting Anticipated Residue Contribution (ARC)
for the overall U.S. population represents 4% of the RfD, and the ARC for
the most highly exposed subgroup, children age one to six, is 8% of the
RfD. Chronic dietary risk from exposure to fenbutatin-oxide is believed to
be minimal.
Occupational and Residential Exposure
Occupational and residential exposure can be expected based on the
use patterns of currently registered products containing fenbutatin-oxide.
The Worker Protection Standard for Agricultural Pesticides (WPS)
established an interim 48-hour restricted entry interval (REI) based on
fenbutatin-oxide's Toxicity Category I eye irritation potential. EPA has
determined that the 48-hour REI should be retained for all WPS sites as a
prudent measure to mitigate risk to workers entering treated areas after
application. The personal protective equipment (PPE) required for early
entry includes coveralls, chemical-resistant gloves, shoes, socks and
protective eyewear.
Uses of fenbutatin-oxide that are outside the scope of the WPS
including occupational and residential use products are required to add
strengthened entry restrictions to their labels.
Human Risk Assessment
Fenbutatin-oxide generally is of low acute toxicity but is a severe eye
irritant. It poses no significant chronic health risks and is classified as a
Group E carcinogen, indicating that it poses no known cancer risk for
humans.
Although people may be exposed to residues of fenbutatin-oxide in
many fruits and other foods, the chronic dietary risk from such exposure is
minimal. Workers and other users may be exposed to fenbutatin-oxide
during and after application to food crops and ornamentals. To mitigate
the risk of eye irritation during these activities, EPA is requiring a 48-hour
REI and use of PPE including protective eyewear for all agricultural uses
within the scope of the WPS, and more stringent entry restrictions for non-
WPS occupational and residential uses.
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Environmental Environmental Fate
AsSGSSniGnt Fenbutatin-oxide is persistent in the environment, with no major
route of dissipation. It is relatively unsusceptible to hydrolysis or
photodegradation in water or on soil. Microbial degradation of fenbutatin-
oxide in soil also is very slow.
Fenbutatin-oxide is relatively immobile in the environment. It is
slightly soluble in water, has a low vapor pressure and binds strongly to
soil. Therefore, it is not expected to leach.
Although fenbutatin-oxide is persistent, residues do not tend to
accumulate in crops planted in previously treated soil. Fenbutatin-oxide
does accumulate in fish tissues.
In the field, fenbutatin-oxide exhibits the same characteristics of
persistence and immobility as in the laboratory. Calculated half-lives
range from 271 days to 1367 days in different States and soils. This long
half-life causes residue levels to increase with each successive application.
Ecological Effects
Fenbutatin-oxide is practically nontoxic to birds on an acute and
subacute dietary basis, and has no effect on their reproduction. It also is
practically nontoxic to mammals and honey bees. However, fenbutatin-
oxide is very highly toxic to freshwater, estuarine and marine fish and
invertebrates.
Ecological Effects Risk Assessment
Although no acute hazard is expected, use of fenbutatin-oxide at
current rates does present the potential for chronic hazard to birds and
mammals. Hazards to bees and nontarget plants are not anticipated.
Acute risk to freshwater fish is expected for all major uses of
fenbutatin-oxide at current application rates. Acute risk to freshwater
invertebrates is only expected for the citrus use, and acute risk to estuarine
invertebrates is expected from both the citrus and the apple uses.
A significant potential for chronic risk to fish exists from the use of
fenbutatin-oxide on citrus. No chronic risk is anticipated for freshwater
and estuarine invertebrates.
Acute risk to endangered birds and mammals is not expected, but
there is a potential for chronic hazard to these organisms. Acute risk to
endangered freshwater fish and invertebrates is expected from all major
uses. Use of fenbutatin-oxide on citrus presents significant potential for
chronic hazard to endangered freshwater and estuarine fish.
Additional Data EPA 1S requiring the following additional generic data for fenbutatin-
Rpnuirpri oxide to confirm its regulatory assessments and conclusions: Discussion of
formation impurities, Ph, bioaccumulation in fish, droplet size spectrum,
and drift field evaluation.
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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 reregi strati on.
All fenbutatin-oxide end-use products must comply with EPA's
current pesticide product labeling requirements, and with the following:
Use Directions (Restricted Use Classification)
All uses of fenbutatin-oxide are declared Restricted, and products
reregistered under this RED must bear a restricted use legend at the top of
the front panel of the label. No other wording or symbols may appear
above the legend and it must begin with the heading,"RESTRICTED USE
PESTICIDE," followed by a brief statement of the reason for the
restricted use classification (ie, "DUE TO VERY HIGH TOXICITY TO
AQUATIC ORGANISMS"). Following this, the terms of the restriction
must be stated as, "For retail sale to and use only by Certified Applicators
or persons under their direct supervision and only for those uses covered
by the Certified Applicator's certification."
Entry Restrictions and Personal Protective Equipment (PPE)
For occupational end-use products, EPA is establishing a 48-hour
restricted entry interval (REI) for each use that is within the scope of the
Worker Protection Standard for Agricultural Pesticides (WPS). The PPE
required for early entry permitted by the WPS is coveralls, chemical-
resistant gloves, shoes plus socks, and protective eyewear.
All end-use products with non-WPS occupational uses must bear the
following entry restriction:
"Do not enter or allow others to enter the treated area until sprays
have dried."
All residential use products must bear the following entry
restriction:
"Do not allow persons or pets to enter the treated area until sprays
have dried."
Other Labeling Restrictions
EPA is requiring the following labeling statements on all end-use
products intended primarily for occupational use:
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."
Engineering Controls: "When handlers use closed systems,
enclosed cabs, or aircraft in a manner that meets the requirements
listed in the Worker Protection Standard (WPS) for agricultural
pesticides (40 CFR 170.240(d)(4-6), the handler PPE requirements
may be reduced or modified as specified in the WPS."
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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."
User Safety Recommendations:
"Users should wash hands before eating, drinking, chewing gum,
using tobacco, or using the toilet."
"Users should remove clothing immediately if pesticide gets inside.
Then wash thoroughly and put on clean clothing."
"Users should remove PPE immediately after handling this product.
Wash the outside of gloves before removing. As soon as possible,
wash thoroughly and change into clean clothing."
Type of Respirator: If the acute inhalation toxicity of the end-use
product is in category I or II, then a respirator is required for
pesticide handlers. A dust/mist filtering respirator (MSHA/NIOSH
approval number prefix TC-21C) is the only type of respirator that
is appropriate to mitigate fenbutatin-oxide inhalation concerns.
Toxicity Statement
Due to the toxicity of fenbutatin-oxide to birds, mammals and
aquatic organisms, all end-use product labels must bear the following
statement:
"This pesticide is toxic to birds, mammals, fish, and aquatic
invertebrates. Do not apply directly to water, or to areas where
surface water is present or to intertidal areas below the mean high-
water mark. Drift and runoff may be hazardous to aquatic organisms
in neighboring areas. Do not contaminate water when disposing of
equipment washwater or rinsate."
Drift Reductions
To mitigate risks posed due to fenbutatin-oxide's high toxicity to
aquatic organisms, all end-use product labels with aerial applications must
bear the following statements for citrus use in Florida:
1) Do not apply within 125 feet of bodies of water such as lakes,
reservoirs, rivers, permanent streams, natural ponds, marshes or
estuaries.
2) Do not apply when gusts or sustained winds exceed 8 mph.
3) The boom length must not exceed 3/4 of the wing or rotor length
(ie, the distance of the outer-most nozzles on the boom must not
exceed 3/4 or the length of the wingspan or rotor).
4) Do not apply at a height greater than 10 feet above the top of the
target plants unless a greater height is required for aircraft safety.
5) Nozzles must always point backward and never be pointed
downwards more than 45 degrees.
6) Do not apply in less than 10 gallons of final spray per acre.
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Regulatory
Conclusion
7) Do not apply east of US Highway #1, south and east of State
Road #846 or south of West Palm Beach Canal.
All end-use products using airblast applications must bear the
following statements for citrus use in Florida:
1) Citrus groves may be planted close to bodies of water. Do not
apply within 25 feet of bodies of water such as lakes, reservoirs,
rivers, permanent streams, natural ponds, marshes or estuaries.
2) For all plantings within 75 feet of bodies of water as described
above, spray trees only form outside the planting away form the
bodies of water.
3) Shut off the sprayer when turning at row ends.
4) Do not apply when gusts or sustained winds exceed 12 mph.
To ensure that the potential risks of this pesticide are not
unreasonable, EPA is classifying fenbutatin-oxide as a Restricted Use
Pesticide and is requiring the registrant to implement certain risk
mitigation measures. Provided that these measures are implemented, all
products containing fenbutatin-oxide as an active ingredient are eligible for
reregi strati on.
The Restricted Use Pesticide classification is appropriate for all uses
of fenbutatin-oxide because many of its use sites are located on or near
bodies of water, and this pesticide is very highly toxic to freshwater and
estuarine aquatic organisms. Fenbutatin-oxide persists in the environment
long after initial application. The potential for serious contamination of
the ecosystem is substantial.
The required risk mitigation measures are designed to reduce the risk
to freshwater and estuarine aquatic organisms found near Florida's citrus
groves. Measures include reduced application rates, label amendments
with instructions to minimize spray drift, development of more accurate
aquatic modeling, and monitoring to determine if fenbutatin-oxide levels
accumulate over multiple years of use.
Fenbutatin-oxide products will be reregistered once the confirmatory
generic data, product-specific data, revised Confidential Statements of
Formula and revised labeling (including the Restricted Use Pesticide
classification) are received and accepted by EPA, assuming that the
required risk mitigation measures also are implemented.
For More
EPA is requesting public comments on the Reregi strati on Eligibility
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Information Decision (RED) document for fenbutatin-oxide 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.
Following the comment period, the fenbutatin-oxide RED document
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 reregi strati on program,
the fenbutatin-oxide RED, or reregi strati on of individual products
containing fenbutatin-oxide, 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.
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