United States
Environmental Protection
Agency
Office of Prevention, Pesticides
And Toxic Substances
(H-7508W)
EPA-738-F-92-001
August 1992
R.E.D. FACTS
Pesticide
Reregistration
lndole-3-Butyric Acid
All pesticides sold or used 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 undue hazards to human health or the environment.
When a pesticide is eligible for reregistration, EPA announces this and
explains why in a Reregistration Eligibility Document, or RED. This fact
sheet summarizes the information in the RED for indole-3-butyric acid
(IBA).
Use Profile
Regulatory
History
IBA is a plant growth regulator, used to promote and accelerate root
formation of plant clippings and to reduce transplant shock of nonfood
ornamental nursery stock. IBA is also used on fruit and vegetable crops,
field crops and ornamental turf to promote growth development of flowers
and fruit and to increase crop yields. IBA has been classified as a
biochemical pesticide because it is similar in structure and function to the
naturally-occurring plant growth hormone indole-3-acetic acid.
Pesticide products containing IBA were first registered in 1960 for use
on ornamental plant cuttings and transplants to promote root growth and to
reduce transplanting shock. In June 1988, EPA issued a Data Call-In
Notice for products containing IBA. Registrants responded by requesting a
low volume minor use data waiver for all applicable guidelines. EPA was
later asked to classify IBA as a biochemical pesticide. Following review,
EPA designated IBA as a biochemical pesticide.
In 1990, new IBA products were registered for use on fruit and
vegetable crops, field crops and ornamental turf, to promote growth and
development of flowers and fruit and to increase crop yields. Thirty-one
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Human Health
Assessment
pesticide products containing IBA with or without other active ingredients
currently are registered.
Toxicity
All generic toxicology data requirements have been waived for IBA.
The registered uses result in very low exposure to workers and negligible
residues on crops. Products are formulated with very low percentages of
IBA (0.0004 to 4.5%) and are applied at ultra-low rates (7 mg IBA/acre).
Formulated products generally are of low toxicity. Additionally, IBA is
metabolized to 3-indole acetic acid which is a common metabolite in
tryptophan (an amino acid) metabolism in humans.
Occupational Exposure
People may be exposed to IBA during mixing, loading and application
activities. However, IBA is of low toxicity and is applied at extremely low
rates, so exposure data have not been required.
EPA has no significant exposure concerns other than protecting the
eyes of mixers, loaders and applicators. Thus, IBA products in Toxicity
Category II for primary eye irritation must bear appropriate label
precautions, including a requirement that applicators wear protective
eyewear (goggles, face shield, or safety glasses).
Human Risk Assessment
The Agency believes the potential risks to humans from occupational
and dietary exposure to IBA are negligible.
Ecological Effects and Environmental Fate
Due to IBA's ultra-low application rates, its behavior as a plant
growth hormone, and its similarity in structure and function to other
naturally occurring chemicals, EPA believes that IBA poses a negligible risk
to the environment. However, to confirm its assumption that the toxicity of
IBA to avian and aquatic species is low, EPA is requiring four ecotoxicity
studies.
Environmental Risk Assessment
EPA concludes for the reasons stated above that the current uses of
IBA pose a negligible risk to the environment.
Additional Data EPA is issuing a data call-in notice with the RED requiring four
RedUJred ecotoxicity studies. These studies are due within eight months after
registrants receive the RED. Additionally, chemistry and acute toxicity data
on formulated products are required within this same period.
Environmental
Assessment
Product Labeling
Changes Required
The labels of the IBA products must comply with EPA's current
pesticide labeling requirements.
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Regulatory
Conclusion
For More
Information
In addition, the labels of IBA products in Toxicity Category II for
primary eye irritation must include the following eye protection/protective
eyewear statement:
"Causes substantial but temporary eye injury. Do not get in eyes or
on clothing. Wear goggles, face shield or safety glasses. Wash
thoroughly with soap and water after handling. Remove contaminated
clothing and wash clothing before reuse."
The accompanying statement of practical treatment should read:
"If in eyes: hold eyelids open and flush with a steady, gentle stream of
water for 15 minutes. If swallowed: drink promptly a large quantity
of milk, egg white and gelatin solution, or if these are not available,
large quantities of water. Avoid alcohol."
• The registered uses of IBA are not likely to cause unreasonable
adverse effects in people or the environment, and are eligible for
reregistration.
• Acute ecotoxicity studies are required to confirm EPA's
assumption that only negligible risks are posed to avian and aquatic animal
species.
• Products that contain IBA as their only active ingredient will be
reregistered once product-specific data and amended labeling are received
and accepted by EPA.
• Products that contain additional active pesticide ingredients will be
reregistered once EPA completes eligibility decisions on the other active
ingredients, and once product specific data and amended labeling are
received and accepted by EPA.
EPA is requesting public comments on the Reregistration Eligibility
Document (RED) for IBA 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 or to submit written comments, please contact the Public
Response and Program Resources Branch, Field Operations Division
(7506C), Office of Pesticide Programs (OPP), US EPA, Washington, DC
20460, telephone 703-305-5805.
In the future, the IBA RED 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 IBA or about EPA's pesticide
reregistration program, please contact the Special Review and Reregistration
Division (7508W), OPP, US EPA, Washington, DC 20460, telephone 703-
308-8000. For information about reregistration of individual IBA products,
please contact the Registration Division (7505C), OPP, US EPA,
Washington, DC 20460, telephone 703-305-5447.
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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, 24 hours a day, seven days a week, or Fax your
inquiry to 806-743-3094.
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