UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460

OFFICE OF 

PREVENTION, PESTICIDES ND A

TOXIC SUBSTANCES

MEMORANDUM

March 6, 2008 

SUBJECT: Sodium Nitrate (076104) and Potassium Nitrate (076103). Human Health Assessment Problem 

Formulation Document in Support of Registration Review. Registration Review Case No. 4052 

Nitrates and Nitrites. DP# 342935. 

FROM: Susan V. Hummel, Chemist and Senior Scientist 

 Reregistration Branch 4 

 Health Effects Division (7509P) 

THRU: Ray Kent, Chief 

 Reregistration Branch 4 

 Health Effects Division (7509P) 

 

TO: Eric Miederhoff, CRM Team 53 

 Reregistration Branch 3 

 Special Review and Reregistration Division (7508P) 

 

Executive Summary 

Attached is the Health Effects Division’s (HED) human health risk assessment problem 

formulation document for the nitrate and nitrites reregistration case to support Registration 

Review. 

Two pesticide active ingredients are part of the nitrates and nitrites reregistration case, sodium 

nitrate, and potassium nitrate. Both of these pesticide ingredients are used in multiple active 

ingredient products also containing carbon, sulfur, and/or sawdust; these products are fumigant 

gas cartridge products intended to be placed in burrows to control small mammals. The use is 

outdoors only. The products have a fuse, which the user lights, and then the cartridge is 

immediately placed inside the burrow, and the burrow entrance covered with dirt. The contents 

of the cartridge burn and release carbon dioxide and toxic gases. 

HED has considered recent risk assessments for sodium and potassium nitrate, updates to its 

toxicity, exposure and usage databases, and the most updated Agency science policy and risk 

assessment methodologies. The most recent risk assessment for sodium and potassium nitrate 

was conducted in 1991 in connection with the Reregistration Eligibility Document (Engler, 

1991). Risks of concern were mitigated by cancellation of the products with risk concerns. 

There are no other changes to the registrations or to the database of studies. 

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HED does not believe that new data are needed for Registration Review and that existing risk 

assessments will support Registration Review. There are no pesticidal food uses, so there is no 

dietary assessment, and no aggregate assessment is required. Residential and occupational 

exposure assessments are available for all uses, and there are no exposure risks of concern. No 

additional human health risk assessments will be needed for the existing uses of sodium nitrate 

and potassium nitrate. 

Introduction 

The most recent risk assessment for sodium nitrate and potassium nitrate was conducted in 1991 

in connection with the Nitrates and Nitrites Reregistration Eligibility Document (Engler, 1991), 

with a supporting occupational and residential exposure assessment (Morris, 1991), and an 

undated, unsigned toxicology assessment. Risks of concern were mitigated by cancellation of 

the products with risk concerns. 

Databases consulted for this problem formulation document include HED databases, OPPIN 

databases, including the label database. HED also conducted an open literature search using 

Google Scholar. 

The only pesticidal use of sodium nitrate and potassium nitrate is in multiple active ingredient 

products also containing carbon, sulfur, and/or sawdust; these products are fumigant gas 

cartridge products intended to be placed in burrows to control small mammals. 

OPPIN lists 3 products containing 46.2 – 53% sodium nitrate, and 3 products containing 38.8 – 

45 % potassium nitrate. There are no technical products containing sodium nitrate or potassium 

nitrate. 

The product labels contain instructions on how to find the burrow, prepare the burrow for the use 

of these products, and the treatment. For treatment, the user is instructed to light the fuse, place 

the cartridge into the burrow, fuse end first, and then close the burrow with plenty of dirt. The 

following cautions are on the product labels: Do Not Inhale! TOXIC FUMES! If smoke is seen 

coming from burrow entrance, plug firmly with soil. 

Chemical Identity 

The chemical identity for sodium nitrate and potassium nitrate are described in the following 

Tables 1a and 2b. 

Table 1a. Chemical Identity of Sodium Nitrate 

Common Name Sodium Nitrate 

Chemical Name Sodium Nitrate 

PC Code 076104 

Chemical Abstracts No. 7631-99-4 

Registration Review 

Case No. 

4052 

Chemical Class Inorganic salt 

Chemical Structure NaNO3

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Table 1b. Chemical Identity of Potassium Nitrate 

Common Name Potassium Nitrate 

Chemical Name Potassium Nitrate 

PC Code 076103 

Chemical Abstracts No. 7757-79-1 

Registration Review 

Case No. 

4052 

Chemical Class Inorganic salt 

Chemical Structure KNO3

The registered products of sodium and potassium nitrate also contain sulfur, carbon, and/or 

sawdust. These products will undergo chemical reactions and produce toxic fumes after ignition. 

Although no toxicity data are available on the fume by products, HED believes that worker and 

bystander exposure scenarios are not likely to exist based on the use patterns (underground) and 

with current label precautions. 

Hazard Identification/Toxicology 

There is very little potential for exposure to sodium or potassium nitrate from the registered 

pesticide uses – gas producing cartridges placed in animal burrows. Because of the registered 

use pattern, many of the normally required toxicity studies were considered unnecessary for 

sodium and potassium nitrate. In addition, these compounds are normally present in the 

environment. Nitrates are in the soil and in plants that take up the nitrates from the soil. Thus, 

there is no reason to expect reasonable pesticide usage to constitute any hazard beyond ordinary 

exposure. 

Sodium nitrate is in Category III for acute oral and dermal toxicity, toxicity Category II for 

primary eye irritation, and toxicity Category IV for primary dermal irritation. Acute inhalation 

toxicity has not been determined. No subchronic toxicity studies are available. In some chronic 

and carcinogenicity studies, sodium nitrate has been reported as carcinogenic, in others it has 

not. There are several positive mutagenicity studies. Nitrate in food may be converted to nitrite, 

which, in large doses, converts the hemoglobin in the blood to methemoglobin, which cannot 

carry oxygen. In addition, nitrite produced can combine with amines to form nitrosamines. 

Many nitrosamines are mutagens and carcinogens under laboratory conditions. 

Potassium nitrate is in Category III for acute oral toxicity. No other toxicity studies were found, 

with the exception of some mutagenicity studies. Some of the mutagenicity studies with 

potassium nitrate were positive. There is no reason to believe that the toxicity of potassium 

nitrate is different from the toxicity of sodium nitrate. 

No additional toxicity data were required as a condition of reregistration. The most recent 

endpoint table for sodium and potassium nitrate is found in the HED chapter for the RED 

(Engler, 1991). 

The product labels contain different first aid instructions, in case the product gets into eyes, skin, 

or on clothing. Cartridge produces oxide of sulfur gasses. Fumes may be harmful if inhaled. If 

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inhaled, and person has poisoning symptoms (headache, nausea, dizziness, and weakness, 

transfer victim to fresh air. Have victim lie down and keep warm. If respiration is adequate 

recovery will be rapid... Once ignited by the fuse, this cartridge will burn vigorously until 

completely spent and is capable of causing severe burns to exposed skin and clothes, and of 

igniting dry grass, leaves, and other combustible materials. 

Conclusions: The toxicological database on potassium and sodium nitrate is adequate for human 

health risk assessment and to support the continuing registration of sodium nitrate and potassium 

nitrate. No new toxicity studies have been received since the last assessment. No re-evaluation 

of toxicological endpoints and/or safety factors is required. Label first aid statements should be 

standardized. 

Dietary Exposure 

There are no pesticidal food uses of potassium and sodium nitrate. Nitrates are listed by the 

Food and Drug Administration as food additives that may be used in curing of fish, meat, and 

meat products and color fixatives (21 CFR 170.60, 21 CFR 172.170). In 21 CFR 181.33, the 

Food and Drug Administration regulations cite prior sanctions issued by the U.S. Department of 

Agriculture for the use of sodium and potassium nitrates in cured red meat products and cured 

poultry products. 

No dietary exposure assessment is required. There is very little possibility of sodium and 

potassium nitrate reaching drinking water sources from the current use pattern. 

Conclusions: No dietary exposure assessment is required. There is very little possibility of 

sodium and potassium nitrate reaching drinking water sources from the current use pattern. 

Residential Exposure 

For both sodium and potassium nitrates, the potential for applicator and post-application 

residential exposure should be minimal, providing the products are used in accordance with label 

instructions. There is no mixing/loading involved with the end use products; therefore, there 

should be no human exposure. 

Aggregate Risk Assessment 

There are no food uses for sodium and potassium nitrate. Residential exposure should be 

minimal. No aggregate risk assessment is required. 

Occupational Exposure 

For both sodium and potassium nitrates, the potential for applicator and post-application worker 

exposure should be minimal, providing the products are used in accordance with label 

instructions. There is no mixing/loading involved with the end use products; therefore, there 

should be no human exposure. 

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There are no dislodgeable foliar residue data available. Soil dissipation residue data are not 

required; nitrates are naturally present in soils and plants that absorb nitrates from the soil. 

There is the potential for dermal burns following premature flare ignition. 

Conclusions: There is sufficient information available to assess occupational exposure. All of 

the occupational exposure scenarios for the registered uses of sodium and potassium nitrates 

have been assessed adequately. No new assessment required. 

Public Health and Pesticide Epidemiology Data 

The Agency’s incident database shows 17 incidents involving sodium nitrate products between 

January 1992 and October 2007. Several of the incidents (4) were listed as property damage. 

One incident cited an injury to a domestic animal, and ten (10) incidents involved injury to 

humans when flames exploded from the gas cartridge and burned hands, legs, or face. 

 

The Agency’s incident database shows 16 incidents involving potassium nitrate products 

between January 1992 and October 2007. Many of the incidents (10) involved injury to humans 

when flames exploded from the gas cartridge and burned hands, legs, or face. The other 

incidents (6) involved are listed as damage to property. 

Severe incidents reported at the time of the RED, resulted in the cancellation of products 

containing higher levels of sodium nitrate.

Tolerance Assessment and International Harmonization 

There are no pesticidal food uses of potassium and sodium nitrate. There are several food 

additive regulations established by FDA for curing and color-fixing in fish, and meat and meat 

products. There is no problem with harmonization of tolerances with international MRLs. 

Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf). The Office of Pesticide Programs 

(OPP) typically considers the highest potential exposures from the legal use of a pesticide when 

conducting human health risk assessments, including, but not limited to, people who obtain 

drinking water from sources near agricultural areas, the variability of diets within the U.S. 

(including different ages, regions, and ethnicities), and people who may be exposed when 

harvesting crops. Should these highest exposures indicate potential risks of concern, OPP further 

refines the risk assessments to ensure that the risk estimates are based on the best available 

information. 

There is no dietary or water exposure from pesticidal uses of sodium and potassium nitrate. 

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Cumulative

Sodium and potassium nitrate have not been identified as part of a common mechanism group. 

No cumulative assessment has been conducted. 

Human Studies

No human studies have been relied on in previous risk assessments. 

Data Requirements 

There are no outstanding data requirements for sodium or potassium nitrate. No new studies are 

needed for registration review. 

References 

Engler, R., 1991. “Reregistration Eligibility Document (RED) for Sodium Nitrate and Potassium 

Nitrate,” EPA Memorandum from Reto Engler to Allan Abramson, dated July 18, 1991. 

Morris, L. 1991. “Review of Potential Occupational and Residential Exposure to Sodium 

Nitrate and Potassium Nitrate for the Reregistration Eligibility Document (RED),” EPA 

Memorandum from Laura Morris to Esther Saito, dated June 26, 1991. 

 

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