United States
Environmental Protection
Agency
Prevention, Pesticides
And Toxic Substances
(7508W)
EPA-738-F-96-033
July 1996
R.E.D. FACTS
Pesticide
Reregistration
Use Profile
Strychnine
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 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 develops
any mitigation measures or regulatory controls needed to effectively reduce
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 explains the basis
for its decision in a Reregistration Eligibility Decision (RED) document.
This fact sheet summarizes the information in the RED document for
reregi strati on case 3133, strychnine.
Strychnine is currently registered for use only below-ground as a bait
application to control pocket gophers. The end-use products are formulated
as a grain-based bait or a paste. Baiting can be done manually, or with the
use of application equipment. Typical application equipment includes a
burrow-builder, which digs artificial tunnels; or an impinger, which
"injects" bait into the animal's tunnel.
Regulatory
History
Strychnine was first registered as a pesticide in the U.S. in 1947.
However, strychnine had been used in the U.S. to control vertebrate animals
for many years prior to 1947.
All strychnine products, except for those products which contain
strychnine at nominal concentrations no greater than 0.5% and which are
limited by their labels to manual below-ground applications, were classified
as restricted use by the Agency in 1978.
In 1983, the Agency published a Federal Register notice announcing
the Agency's intent to cancel certain uses and to limit others. In 1988,
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Human Health
Assessment
above-ground uses of strychnine were prohibited by a U.S. Court injunction
and strychnine products with those uses remain temporarily cancelled.
Since 1988, the U.S. Fish and Wildlife Service has issued several
opinions on uses of strychnine products.
Several Data Call-Ins have been issued for strychnine, including
requirements for efficacy, benefits, environmental fate and chemistry data,
and ecological effects data.
Toxicity
The human health assessment for strychnine is based on the acute
toxicity for the technical and is described below. Because of the high acute
toxicity via the oral and ocular routes, subchronic and chronic data were not
required. Strychnine has been placed in Toxicity Category I, indicating the
greatest degree of acute toxicity, for oral and ocular effects; inhalation
toxicity is also presumed to be high. A confirmatory 21-day dermal study
is required to describe the dermal absorption. Additional data are also
required to describe the acute toxicity of the end-use products intended for
homeowner use.
A substantial number of accidental exposures to strychnine pesticides
are reported annually to Poison Control Centers.
Dietary Exposure
Given the below-ground use pattern, strychnine residues on dietary
items are not likely.
Occupational and Residential Exposure
Based on current use patterns, handlers (mixers, loaders, and
applicators) may be exposed to strychnine during normal use of bait
formulations below-ground. Strychnine is highly acutely toxic by the oral
and ocular and presumably by the inhalation routes of exposure. In
addition, numerous incidents have been reported. Additional information
including poisoning incident data and end-use product acute toxicity are
required for EPA to reach a decision on eligibility for residential uses.
Human Risk Assessment
Strychnine is generally of very high acute toxicity. However, dietary
exposure is not expected because of the below-ground application.
Of greater concern is the risk posed to strychnine handlers,
particularly applicators. Exposure and risk to the certified pest control
operators will be mitigated by the use of personal protective equipment
required in this RED. To mitigate risks to handlers, EPA is requiring
personal protective equipment (PPE) including chemical resistant gloves,
eye protection, and dust masks. The Agency remains concerned for risks to
homeowners and children from strychnines non-occupational uses.
Therefore, additional information from poison control center and product-
specific acute toxicity data are required to evaluate these risks. In the
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Environmental
Fate Assessment
interim, all homeowner products containing strychnine are required through
this RED to be contained in Child-Resistant Packaging to reduce the
potential for accidental exposure to children.
Environmental Fate
Available data satisfy the environmental fate requirements for below-
ground uses. In the event that above-ground uses are restored, additional
data appropriate to support the registration of these uses will be required.
Ecological Effects
Acute toxicity of strychnine to birds is assumed to be very high.
Subacute dietary data indicate that strychnine ranges from slightly to highly
toxic to avian species. Strychnine may pose a threat to birds who may be
subject to repeated or continuous exposure from spills. Avian reproduction
data indicate no treatment related effects in the bobwhite quail. However,
in the mallard duck, testes were smaller at the low dose and chick body
weights were reduced in the mid dose and high dose groups. Egg
production and adult female body weight were also reduced at the high
dose.
Mammalian studies indicate that strychnine is very highly toxic to
small mammals on both an acute oral basis and dietary basis. The signs of
toxicity, including death, occurred within one hour.
Acute freshwater fish data reveal that strychnine ranges from
moderately to highly toxic to freshwater fish. Aquatic invertebrate acute
toxicity data indicate that strychnine is moderately toxic to aquatic
invertebrates.
Ecological Effects Risk Assessment
The Agency believes that the risks to non-target terrestrial animals are
minimal when strychnine is used below-ground. When the recommended
precautions are followed, below-ground use of strychnine does not
constitute a risk to non-target or endangered species.
To mitigate risks of potential toxicity posed by strychnine, EPA is
requiring the following risk mitigation measures:
° use of personal protective equipment
° child-resistant packaging for products available to the general public.
Additional Data The Agency is requiring product-specific data including product
Required chemistry and acute toxicity studies, revised Confidential Statements of
Formula (CSFs), and revised labeling for reregi strati on. A 21-day dermal
study is also required to confirm the assumption that dermal absorption is
low.
Risk Mitigation
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Product Labeling
Changes
Required
Additional information is being required prior to making a decision
for the use of strychnine products by homeowners. This information
includes poison control center data for products used by homeowners to
include incident reports for poisoning of children, and end-use product
acute toxicity data.
Manufacturing-use products
The MP labeling must bear the following statement under Directions
for Use:
"This product may be used only to formulate end-use
rodenticide concentrates of ready-to-use baits which are limited
by labeling to below-ground applications to control pocket
gophers."
End-use products
All end-use strychnine products will be required to comply with
EPA's current pesticide product labeling requirements and with the
following.
Restricted-use products must bear the following statement in a
prominent location on the front panel of the end-use product labeling:
"RESTRICTED-USE PESTICIDE
ACUTE ORAL TOXICITY
For retail sale and use only by Certified Applicators or persons
under the direct supervision of a Certified Applicator, and only
for those uses covered by the Certified Applicator's certification.
Sale to or use by the general public is prohibited."
The minimum (baseline) PPE for strychnine end-use products
formulated as a paste is:
"Applicators and other handlers must wear:
—long-sleeved shirt and long pants,
—chemical-resistant gloves*,
—shoes plus socks, and
—protective eyewear.
The minimum (baseline) PPE for strychnine end-use products
formulated as grain-based baits is:
"Applicators and other handlers must wear:
—long-sleeved shirt and long pants,
—chemical-resistant gloves*,
—shoes plus socks, and
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—dust mask.
* For the glove statement, use the statement established for strychnine
through the instructions in Supplement Three of PR Notice 93-7. Although
this PR Notice addresses agricultural pesticides, the basis for our decisions
for strychnine are similar.
The Agency is requiring the following labeling statements to be
located on all end-use products containing strychnine that are intended
primarily for occupational use.
Application Restrictions
"Do not apply this product in a way that will contact workers, other
persons, pets, or domestic animals."
User Safety Requirements
"Follow manufacturer's instructions for cleaning/maintaining PPE. If
no such instructions 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."
All use sites must be listed on the label. Specifically, these are to
include use sites, such as orchards, forests, nurseries, and agricultural crop
areas.
EPA has determined that products containing strychnine labeled for
Conclusion below-ground use and used by certified applicators are eligible for
reregi strati on. The Agency has not made a determination for those products
labeled for sale and use by the general public.
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Based on the generic data reviews for strychnine and the use of
products below-ground, the Agency has concluded that for the restricted
use products it has sufficient information about strychnine's potential to
cause adverse effects to humans or the environment. The Agency has
concluded that the use of the products classified as restricted use, labeled
and used as specified in this Reregi strati on Eligibility Decision, will not
pose unreasonable adverse effects to humans or the environment.
Therefore, these products are eligible for reregi strati on. Pesticide handlers
of the paste products are to wear the PPE of chemical resistant gloves and
protective eyewear to mitigate exposure and risks of acute toxicity from
strychnine. A dust mask is required for pest control applicators using the
grain-based baits. Also, a 21-day dermal study is required as confirmatory.
However, for the remaining products, those unclassified and available
for use by the general public, EPA has concluded that it does not have
sufficient information regarding the risks to humans and benefits from the
use of these products to make a decision of eligibility. The Agency is
requiring that strychnine product registrants provide poison control center
data for products used by homeowners, incident reports for poisoning of
children, and end-use product acute toxicity. This information will be used
to determine if the use of these products below-ground by the general
public will result in unreasonable adverse risks to humans or the
environment.
After receipt, EPA will review the additional information requested
and decide whether additional practical measures are prudent to protect the
general public users from the risks of poisonings or whether other
regulatory action is appropriate. At that time the Agency will reach a
decision on reregi strati on eligibility for the products intended for use by
homeowners.
For More
Information
EPA is requesting public comments on the Reregi strati on Eligibility
Decision (RED) document for strychnine 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 Reregi strati on Information System
at 703-308-7224. They also are available on the Internet on EPA's gopher
server, GOPHER.EPA.GOV, or using ftp on FTP.EPA.GOV, or using
WWW (World Wide Web) on WWW.EPA.GOV.
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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 strychnine 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 reregi strati on program,
the strychnine RED, or reregi strati on of individual products containing
strychnine, please contact the Special Review and Reregi strati on 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 9:30 am and 7:30 pm Eastern Standard
Time, Monday through Friday.
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