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). Hu man Health Assessment Problem Formulation Document in Support of Registratio n 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 Rere gistration Division (7508P)

Executive Summary

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

formulation document for the nitrate and nitrites reregist ration case to support Registration

Review.

Two pesticide active ingredients are part of the nitrates and nitrites rere gistration case, sodium nitrate, and potassium nitrate. Both of these pesticide ingredients are used in multiple active ingredient products also contai ning 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 th e user lights, and then the cartridge is immediately placed inside the burrow, and the burro w entrance covered with dirt. The contents of the cartridge burn and release carbon dioxide and toxic gases.

HED has considered recent risk assessments fo r sodium and potassium nitrate, updates to its toxicity, exposure and usage databases, and th e 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 Re registration Eligibility Document (Engler, 1991). Risks of concern were mitigated by cance llation of the products with risk concerns. There are no other changes to the registra tions or to the database of studies.

Page 1 of 6HED does not believe that new data are needed for Registration Review and that existing risk assessments will support Registration Review. Ther e are no pesticidal food uses, so there is no dietary assessment, and no aggregate assessmen t is required. Residential and occupational exposure assessments are available for all uses, an d 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 n itrate and potassium nitrate was conducted in 1991

in connection with the Nitrates and Nitrites Reregistration Elig ibility Document (Engler, 1991), with a supporting occupa tional and residential exposure as sessment (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 formul ation document include HED databases, OPPIN databases, including the label database. HED al so conducted an open literature search using Google Scholar.

The only pesticidal use of sodium nitrate and pot assium 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 containi ng 46.2 – 53% sodium nitrate, and 3 products containing 38.8 – 45 % potassium nitrate. There ar e no technical products containi ng 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 NaNO 3

Page 2 of 6Table 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 KNO 3

The registered products of sodium and potassi um nitrate also contai n sulfur, carbon, and/or sawdust. These products will undergo chemical r eactions and produce toxic fumes after ignition. Although no toxicity data are available on the fu me by products, HED believes that worker and bystander exposure scenarios are no t 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 so dium or potassium nitrate from the registered pesticide uses – gas producing ca rtridges placed in animal burrows. Because of the registered use pattern, many of the normally required toxici ty studies were considered unnecessary for sodium and potassium nitrate. In additi on, these compounds are normally present in the environment. Nitrates are in the soil and in plants that take up the nitrat es 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 toxic ity Category IV for primary derm al irritation. Acute inhalation toxicity has not been determined. No subchronic t oxicity studies are availa ble. 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 additio n, 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 t oxicity studies were found, with the exception of some muta genicity studies. Some of the mutagenicity studies with potassium nitrate were positive. There is no r eason 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 nitr ate is found in the HED chapter for the RED (Engler, 1991).

The product labels contain different first aid instructions, in case th e product gets into eyes, skin, or on clothing. Cartridge produces oxide of sulfur gasses. Fumes may be harmful if inhaled. If

Page 3 of 6inhaled, and person has poisoni ng 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 a nd sodium nitrate is adequate for human

health risk assessment and to s upport the continuing registration of sodium nitrate and potassium nitrate. No new toxicity studies have been recei ved 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 a nd 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 CF R 170.60, 21 CFR 172.170). In 21 CFR 181.33, the Food and Drug Administration regula tions cite prior sanctions issu ed 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. Ther e is very little possibility of sodium and potassium nitrate reaching drinking water sources from the current use pattern.

Conclusions: No dietary exposure assessment is requi red. 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 mi xing/loading involved with the en d use products; therefore, there should be no human exposure.

Aggregate Risk Assessment

There are no food uses for sodium and potassi um nitrate. Residen tial exposure should be minimal. No aggregate risk assessment is required.

Occupational Exposure

For both sodium and potassium nitrates, the poten tial for applicator and post-application worker exposure should be minimal, providing the pr oducts are used in accordance with label

instructions. There is no mi xing/loading involved with the en d use products; therefore, there should be no human exposure.

Page 4 of 6There are no dislodgeable foliar residue data av ailable. Soil dissipati on residue data are not required; nitrates are naturally present in soils an d plants that absorb nitrates from the soil.

There is the potential for dermal bur ns following premature flare ignition.

Conclusions: There is sufficient information availabl e to assess occupational exposure. All of the occupational exposure scenarios for the regist ered 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 incide nts involving sodium nitrate products between January 1992 and October 2007. Several of the in cidents (4) were listed as property damage. One incident cited an injury to a domestic anim al, 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 inci dents 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 a nd 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 curi ng and color-fixing in fish, and meat and meat products. There is no problem with harmonizat ion of tolerances with international MRLs.

Environmental Justice

Potential areas of environmental ju stice concerns, to the extent possi ble, were considered in this human health risk assessment, in accordance w ith U.S. Executive Order 12898, "Federal Actions

to Address Environmental Just ice in Minority Populations an d Low-Income Populations," http://www.eh.doe.gov/oepa/ guidance/justice/eo12898.pdf ). The Office of Pesticide Programs (OPP) typically considers the highest potential expos ures 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 area s, the variability of diets within the U.S. (including different ages, regions, and ethnicities), and peopl e who may be exposed when harvesting crops. Should these highest exposures i ndicate potential risks of concern, OPP further

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

information.

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

Page 5 of 6Cumulative

Sodium and potassium nitrate have not been id entified 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 sodi um or potassium nitrate. No new studies are needed for registration review.

References

Engler, R., 1991. “Rereg istration Eligibility Do cument (RED) for Sodium Nitrate and Potassium Nitrate,” EPA Memorandum from Reto Engl er to Allan Abramson, dated July 18, 1991.

Morris, L. 1991. “Review of Potential Occupa tional and Residential Exposure to Sodium Nitrate and Potassium Nitrate for the Reregi stration Eligibility Document (RED),” EPA

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

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