United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508C)
EPA-OOO-F-99-002
EPA-OOO-R-99-002
March 1999
R.E.D. FACTS
Pesticide
Reregistration
Ryanodine
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 before
November 1, 1984, 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. To implement provisions of the Food
Quality Protection Act of 1996, EPA considers the special sensitivity of infants
and children, as well as aggregate exposure of the public to residues of the
pesticide from all sources, and the cumulative effects of the pesticide and other
compounds with common mechanisms of toxicity. The Agency develops any
mitigation measures or regulatory controls needed to reduce each pesticide's risks.
EPA reregisters pesticides that meet the safety standard of FQPA and can be used
without posing unreasonable risks to human health or the environment.
When EPA reaches a decision regarding a pesticide's eligibility for
reregistration, the Agency announces this in a Reregistration Eligibility Decision
(RED) document and provides opportunity for public comment. Alternatively,
some pesticides are withdrawn from the reregistration process prior to the comple-
tion of a formal RED document. This fact sheet serves as and explains the
Agency's Reregistration Eligibility Decision for Ryanodine (reregistration case
2595), which consists of a voluntary cancellation of this pesticide.
Description of
Chemical
Common Name:
Trade Names:
Empirical Formula:
Chemical Abstracts Service (CAS) No.
EPA Shaughnessy Code:
Year of Initial Registration:
Year of Patent:
Pesticide Type:
Ryanodine
Ryanodine, Ryanocide, Ryania
C25H35NO9 or C26H37NO9
15662-33-6
071502
1968
1945 Patent No. 2,400,295
Insecticide
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Chemical Family:
U.S. and Foreign Producers
Plant Alkaloid
None
Use Profile and For-
mulations
Science
Background
Use History and
Regulatory Status
Ryanodine was a botanical or non-synthetic insecticide used in integrated
pest management and organic farming. This pesticide was registered for the
control of citrus thrips on citrus, codling moth on apples, pears and walnuts, and
European corn borer on corn. In fact, it has only been used on apples and citrus.
On these crops it was used primarily by growers interested in avoiding use of
longer lived residual products, controlling pesticide resistant insects (primarily
phosphate resistant populations), and practicing "organic" insect control. Histori-
cally it has also had broad spectrum uses by homeowners on food and feed crops
and in residences to control roaches.
Formulations were based on an active ingredient isolated from the wood of
Ryanis speciosa. End-use products were powder or wetable powders containing
5.5% to 22% active ingredient, and formulation intermediates containing 45%
active ingredient.
Ryania has been used commercially as a pesticide spray since the early
1940's. Several LD50 studies conducted in 1948 helped establish the safety of use
of powered ryania stems as an insecticide. However, these studies lacked accurate
quantization of the alkaloid active ingredient. They established the acute oral
toxicity of powdered stems of Ryania speciosa to be: 1200 mg/kg in rats; 150
mr/kg in dogs; more than 400 mg/kg in monkeys; 650 mg/kg in rabbits; 650
mg/kg in mice; 2500mg/kg in guinea pigs; and more than 3000mg/kg in chickens.
These and other studies on the effects of ryanodine on vertebrates and inverte-
brates revealed powerful effects on striate muscle contraction.
Because of the lack of persistance of ryania or ryanodine in the environment,
residues did not result in the food chain or the human diet. Bobwhite quail and
mallard duck have been shown not to be acutely sensitive to low doses of ryania.
The NOEL in dietary LC50 testing was 3160 ppm and 5620 ppm for bobwhite
quail and mallard duck respectively. Ryania is acutely toxic to Daphnia magna
neonates, with an LC50 48 hour value of 44 ppm. This toxicity would require
application methods that prevent spray drift from reaching ponds and other water
sources. Primary eye irritation testing has shown moderate to temporary irritation
in the non-rinsed eye, but no irritation in the rinsed eye. Primary dermal irritation
testing showed no irritation, and no skin sensitization was shown in either dermal
or guinea pig skin sensitization.
Ryania was available for many years and was used commercially as a
pesticide spray since the early 1940's. As synthetic insecticides became more
available and less expensive, use of ryania declined. In the early 1950's, at its
maximum use, approximately one million pounds of 40% ryania (400,000 pounds
of active ingredient) were used each year. By contrast, by 1990, only about 200
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pounds of ryania were used per year. Prior to its voluntary cancellation, ryania's
partial resurgence in the market place was due to its use in integrated pest manage-
ment programs. Both apples and citrus have singular insect pests that are not
routinely controlled by predators. Ryania's mode of action, which differed from
that of the widely used phosphate-carbamates (acetycholine esterase inhibitors),
enabled it to control phosphate resistant insects on these crops. Nevertheless, in
recent years, use of ryania has been small and insignificant except among those few
growers deriving value from its use.
In 1989, the Agency considered requests by registrants for waivers of
required toxicity tests based on their products' low volume/minor use. Registrants
were advised that certain minimal toxicity data were needed before EPA could
consider waiving additional, more complex studies. A data call-in (DCI) was
issued in June 1991. As of September 1996, five reregistration data requirements
remained outstanding: 81-3; 82-la; 83-3a; 84-2a; and 84-2b. These requirements
constituted part of the minimal toxicity data that the Agency needed to consider
ryania's reregistration eligibility. Rather than submitting the required data, the
registrants requested voluntary cancellation.
In accordance with section 6(f)(l) of the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA), on January 22, 1997, the Agency issued a notice in the
Federal Register (vol. 62, No. 14, pp. 3284-3287) of receipt of a request by the
registrant to voluntarily cancel all remaining ryanodine containing products and the
start of a 180 day public comment period. After the comment period expired with
no comments received, voluntary cancellation of all remaining registered ryanodine
containing products and the active ingredient became final on July 23, 1997.
For More Contact Person at EPA:
Information Mark Wilhite
Office of Pesticide Programs, EPA,
Special Review and Reregistration Division (7508C)
401 M Street, S.W.
Washington, D.C. 20406
(703) 308-8586
Electronic copies this fact sheet are available on the Internet. Please see
http://www.epa.gov/REDs.
For information about the health effects of pesticides, or for assistance in recogniz-
ing and managing pesticide poisoning symptoms, please contact the National Pesticide
Telecommunications Network (NPTN). Call toll-free 1-800-858-7378, between 6:30 am
and 4:30 pm Pacific Time, Monday through Sunday. The NPTN website is:
http://www.ace.orst.edu/info/nptn/.
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