United States
Environmental Protection
Agency
Pesticides And
Toxic Substances
(7508W)
738-F-91-103
September 1991
R.E.D. FACTS
Pesticide
Reregistration
Use Profile
Inorganic Nitrate/Nitrite
(Sodium and Potassium
Nitrates)
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, showing 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 inorganic nitrate/nitrite,
or sodium and potassium nitrates.
Sodium and potassium nitrates are pyrotechnic fumigants used as
rodenticides, predacides and insecticides. Each compound is combined with
other pesticide active ingredients (sulfur and carbon) and loaded into
fumigant gas cartridges, which are designed to be ignited and placed in pest
burrows. The ignited cartridge bombs produce toxic gases which are lethal
to target rodents, skunks, coyotes and ground-nesting wasps.
Both sodium and potassium nitrates are naturally occurring, common
chemical compounds. While they have limited pesticidal uses, both have
other industrial uses. Potassium nitrate is used in the production of
fireworks, blasting powders and gunpowder. Sodium nitrate is used in
producing other chemicals, glass, fertilizer and fireworks.
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Regulatory
History
Human Health
Assessment
The first of the six currently registered sodium and potassium nitrate
pyrotechnic cartridge products was registered in 1948. A high rate of
accidents, attributed to poor labeling and improper manufacture, prompted
EPA to issue a Notice of Intent to Cancel these products, in 1982. In
response, the registrants improved product labeling and provided adequate
data on fuse and cartridge burn times.
Few studies were needed by EPA to assess the potential health
hazards, exposures and risks of sodium and potassium nitrates. Both are
common chemical compounds with very limited uses as pesticides, and both
are marketed in cartridges which prevent accidental exposure to the
chemicals themselves.
Both sodium and potassium nitrates control target pests through an
unconventional mode of action. Rather than directly poisoning rodents, they
support the combustion of charcoal in gas cartridges, thus aiding in the
production of toxic gases, which, when released, overtake the target pest.
Therefore, EPA is concerned less about the risk of direct human exposure to
sodium or potassium nitrates, than about accidents associated with use of the
gas cartridge bombs—typically involving skin burns or inhalation of toxic
gases. (Please see the Applicator Exposure section below.)
Toxicity
EPA has sufficient information on the toxicology of sodium and
potassium nitrates to support their eligibility for reregistration.
Available acute toxicity studies indicate that sodium nitrate may cause
eye irritation (Toxicity Category II effect level, with Category I indicating
the greatest toxicity and Category IV the least). However, both sodium and
potassium nitrates pose a relatively low acute oral toxicity hazard (Toxicity
Category III). Sodium nitrate also produces some low level acute dermal
effects (Toxicity Category III), and slight dermal irritation (Toxicity
Category IV).
Available chronic toxicity studies indicate some effects on the blood,
as well as equivocal evidence of carcinogenicity. However, these studies
are not considered relevant because people are not chronically exposed to
these chemicals used as pesticides.
Dietary Exposure
Although pesticide products containing potassium nitrate are registered
for use in agricultural areas, they are used in a manner that does not bring
them into contact with crops. Therefore, residues are not expected to
remain in or on food or feed crops, and tolerances (legal residue limits)
need not be established.
Applicator Exposure
The only people potentially exposed to sodium and potassium nitrates
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should be applicators, and they should be exposed only minimally. These
chemicals are completely encased in cartridges, similar to flares. Unlike
many other pesticides, they do not splash, spill or create dust or spray
particles. Further, once ignited, these products produce noxious gases
inside the pest burrow, which is sealed or covered. Therefore, the
applicator's dermal and inhalation exposure to these pesticides and the gases
they produce should be negligible.
In the past, EPA received reports of incidents involving dermal burns,
caused by improper handling of ignited cartridges or by defective cartridges.
One fatality occurred as a result of gross misuse. In 1982, the Agency
issued a Notice of Intent to Cancel sodium and potassium nitrate products,
which elicited some improvements in labeling and manufacturing processes.
However, since then, EPA has received four more reports of injuries to
applicators, due mainly to defective cartridges. The Agency is issuing a
Data Call-In Notice in conjunction with this RED, to address the issue of
defective cartridges and further improve the safety of these products.
Human Risk Assessment
EPA believes that sodium and potassium nitrates, as currently
registered for use as pesticides, do not present any unreasonable adverse
effects to humans. As long as applicators use the gas cartridge products
properly, in accordance with approved labeling, they should be exposed to
virtually none of the chemicals themselves, and to only negligible amounts
of the gases produced. EPA is requiring that registrants develop acute
toxicity data on the gases, and will make final product reregistration
decisions after reviewing these data.
All environmental fate and ecological effects data requirements for
AsSGSSITIGnt sodium and potassium nitrates have been waived, as explained below.
Environmental Fate
Sodium and potassium nitrates are naturally occurring substances
whose physical properties are well understood. The pyrolysis of these
products results in simple organic and inorganic compounds, mostly in the
form of gases, which diffuse through burrow openings or into the soil.
Exposure of the environment is limited and localized, however, and
environmental fate studies are not required.
Ecological Effects
The pesticide products containing these active ingredients are intended
to kill certain vertebrates and wasp pest species inhabiting burrows. Since
these pesticides are applied below the surface of the ground, avian and
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Additional Data
Required
Product Labeling
Changes Required
Regulatory
Conclusion
aquatic species are not exposed. However, any organism in a properly
treated burrow is likely to be killed. EPA is concerned about potential
impacts to non-target and endangered species.
Several types of non-target organisms, including burrowing owls, may
inhabit the burrows of target pests. EPA is developing more extensive and
explicit labeling to modify the timing of applications, and to caution
applicators to observe signs indicating the presence of target pests and the
absence of non-target organisms.
Endangered species that inhabit burrows also are at potential risk. As
a result of several earlier consultations with the Fish and Wildlife Service,
EPA already requires endangered species labeling to protect the six species
identified as being at risk. Another ongoing consultation may cause EPA to
require further label revisions in 1992.
While EPA has all the generic studies needed to support the
reregistration of sodium nitrate, the Agency still needs information
regarding potassium nitrate's composition, recovering and refining process,
and impurities. In addition, product-specific data, including accident
reports and information on manufacturing processes and fuse burn times,
still are needed for products containing both active ingredients. EPA is
issuing a Data Call-in Notice in conjunction with this RED, to obtain this
generic and product-specific information.
The labels of end-use products containing sodium or potassium nitrate
must comply with EPA's current pesticide labeling requirements. In
addition, the Agency soon will issue detailed guidance on labeling for gas
cartridge products, which will address concerns regarding applicator safety
and protection of non-target and endangered organisms.
• Registered pesticide products containing sodium and potassium
nitrates can be used without causing unreasonable adverse effects
in people or the environment. Therefore, they are eligible for
reregistration.
• The four end-use products containing sodium nitrate will be
reregistered once product-specific data and revised labeling
are received and accepted by EPA, and once any data and
labeling needed for the other active ingredients in these products
(sulfur and carbon) also are received and accepted.
• The two end-use products containing potassium nitrate will be
reregistered once generic and product-specific data and revised
labeling are received and accepted by EPA, and once any data
and labeling needed for the other active ingredients in these
products (sulfur and carbon) also are received and accepted.
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For MorG EPA is requesting public comments on the Reregistration Eligibility
Information Document for sodium and potassium nitrates 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 703-557-2805.
In the future, the 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 sodium and potassium nitrates 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 nitrate products, please contact the Registration Division
(7505C), OPP, US EPA, Washington, DC 20460, telephone 703-557-5447.
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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