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Docket Number EPA-HQ-OPP-2014-0655

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Sodium Fluoride Registration Review Team

Human Health

Jonathan Leshin

Timothy Dole

Julie VanAlstine

Environmental Fate and Effects

William Erickson

Siroos Mostaghimi

Najm Shamim

Risk Management

SanYvette Williams

Stacey Grigsby

Jacqueline Hardy

Rose Kyprianou

Office of General Counsel

Philip Ross
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Table of Contents

Introduction...........................................................................................................................5

Anticipated Data Needs ........................................................................................................5

Statutory and Regulatory Authority......................................................................................5

Sodium Fluoride Chemical Facts..........................................................................................6

Use/Usage Information .........................................................................................................6

Recent Actions......................................................................................................................7

Scientific Assessments..........................................................................................................7

7.1 Human Health Assessment.............................................................................................7

7.1.1 Hazard Characterization and Risk ..........................................................................7

7.1.2 Dietary Exposure Assessment.................................................................................7

7.1.3 Food Tolerances......................................................................................................7

7.1.4 Residential and Occupational Exposure Assessment .............................................7

7.1.5 Human Health Incidents .........................................................................................8

7.2 Environmental Risk Assessment....................................................................................8

7.2.1 Environmental Fate and Exposure..........................................................................8

7.2.2 Ecological Risk Characterization............................................................................8

7.2.3 Threatened and Endangered Species ......................................................................9

7.2.4 Ecological Incidents................................................................................................9

7.3 Endocrine Disruptor Screening Program (EDSP)..........................................................9

Interim Registration Review Decision................................................................................10

Next Steps and Timeline.....................................................................................................10

Appendix A Toxicology Profile.............................................................................................12

List of Tables

Table 1 – Chemical Facts for Sodium Fluoride .............................................................................. 6

Table 2 – Registration Review Schedule for Sodium Fluoride .................................................. 11
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Introduction 

This document is the Environmental Protection Agency’s (EPA or “the agency”) Interim 

Registration Review Decision for sodium fluoride (NaF). It is being issued pursuant to 40 CFR

Sections 155.56 and 155.58. A registration review decision is the agency's determination 

whether a pesticide meets, or does not meet, the standard for registration in the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA). The agency may issue, when it 

determines it to be appropriate, an interim registration review decision before completing a 

registration review. Among other things, the interim registration review decision may require 

new risk mitigation measures, impose risk mitigation measures, identify data or information 

required to complete the review, and include schedules for submitting the required data, 

conducting the new risk assessment and completing the registration review. 

The Proposed Interim Registration Review Decision for sodium fluoride was issued for public 

comment on December 24, 2014 and closed on February 23, 2015. During the 60-day public 

comment period, no comments were received concerning registration review of NaF. As a 

result, no changes were made to the document.

Sodium fluoride is registered for use as a wood preservative to protect the groundline portion of 

existing wooden utility poles. It is formulated into an impregnated pole wrap material. The first 

product containing sodium fluoride as an active ingredient was registered in 1964, and it has 

been used chiefly as a wood preservative. There is currently one technical and one end use 

product with sodium fluoride as an active ingredient and all other previously registered sodium 

fluoride products have been cancelled. The Reregistration Eligibility Decision document (RED) 

for sodium fluoride was issued in 2007.

1

 Documents associated with this registration review 

can be found in docket EPA-HQ-OPP-2014-0655 at www.regulations.gov.

Anticipated Data Needs

There are no anticipated data needs to support the registration review for sodium fluoride.

Statutory and Regulatory Authority

The Food Quality Protection Act (FQPA) of 1996, mandated the continuous review of existing 

pesticides. All pesticides distributed or sold in the United States generally must be registered by 

the EPA based on scientific data showing that they will not cause unreasonable risks to human 

health or to the environment when used as directed on product labeling. The registration review 

program is intended to make sure that, as the ability to assess and reduce risk evolves and as 

policies and practices change, all registered pesticides continue to meet the statutory standard of 

no unreasonable adverse effects to human health or the environment. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the registration review 

program, the agency periodically reevaluates pesticides to make sure that as these changes occur, 

 1 Located at http://www.epa.gov/oppsrrd1/reregistration/sodium-fluoride
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products in the marketplace can continue to be used safely. Information on this program is 

provided at www2.epa.gov/pesticide-reevaluation.

The agency is implementing the registration review program pursuant to FIFRA section 3(g) and 

will review each registered pesticide every 15 years to determine whether it continues to meet 

the FIFRA standard for registration. The regulations governing registration review begin at 40 

CFR 155.40. The agency will consider benefits information and data as required by FIFRA. 

The public phase of registration review begins when the initial docket is opened for each case. 

The docket is the Agency’s opportunity to state what it knows about the pesticide and what 

additional risk analyses and data or information it believes are needed to make a registration 

review decision.

Sodium Fluoride Chemical Facts

Sodium fluoride chemical facts are shown in Table 1 below. 

Table 1 – Chemical Facts for Sodium Fluoride

Chemical Name Sodium fluoride

Pesticide type Wood preservative

Case 3132

Chemical Classification Inorganic, ionic

PC Code 075202

CAS Number 7681-49-4

Year first registered 1964

Reregistration Eligibility Decision 

(RED) 2007

Dual use Antimicrobial use only

40 CFR Citation There are no registered food/feed uses and no established tolerances 

for NaF.

Antimicrobials Division, Chemical 

Review Manager SanYvette Williams, williams.sanyvette@epa.gov, (703)305-7702

Antimicrobials Division, Product 

Manager Jacqueline Hardy, hardy.jacqueline@epa.gov, (703)308-6416

Use/Usage Information

Sodium fluoride is registered for use as a wood preservative to protect the groundline portion of 

existing wooden utility poles. There is one technical (EPA Reg. No. 75341-19) and one end use 

product (EPA Reg. No. 75341-4), and they contain 97.5 and 70.6 percent sodium fluoride, 

respectively. The product is formulated into an impregnated pole wrap material. The pole wrap 

is placed around a 20 inch deep excavated section of the pole and stapled or tacked to the pole, 

and the earth is replaced to two inches above the original groundline.
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Recent Actions

There are no recent actions for sodium fluoride.

Scientific Assessments

The agency’s human health and environmental fate and ecological risk assessments for sodium 

fluoride which were conducted for the 2007 RED can be found in the public docket EPA-HQOPP-2007-0833 at www.regulations.gov.

7.1 Human Health Assessment

7.1.1 Hazard Characterization and Risk

The toxicological database is considered adequate for characterizing hazard and assessing risk 

from the use of NaF (see Appendix A for more information). No additional studies are 

anticipated to be needed for registration review.

7.1.2 Dietary Exposure Assessment

The only FIFRA-registered use of sodium fluoride is as a wood preservative (utility pole wrap). 

This use is not expected to result in direct or indirect dietary (food) or drinking water exposure. 

Although sodium fluoride has been cleared by FDA as an indirect food additive for use as a

bonding agent for aluminum foil, stabilizer, or preservative, a dietary assessment is not required 

since this use pattern does not have a registration under FIFRA. A drinking water assessment is 

not required at this time.

7.1.3 Food Tolerances

There are no U.S. tolerances or exemptions from tolerances for sodium fluoride because there are 

no currently registered uses under FIFRA for this active ingredient associated with food or feed.

7.1.4 Residential and Occupational Exposure Assessment

There are no toxicological endpoints for repeat dose dermal exposure to sodium flouride; 

therefore, repeat dose dermal exposures do not need to be assessed. Although there is a hazard 

from acute dermal exposure due to the corrosive nature of sodium flouride, this hazard is 

minimized by the formulation as a wrap and the label-required PPE. The label required PPE 

includes elongated chemical resistant sleeves and chemical resistant gloves.

Because sodium flouride is of low volatility, inhalation exposures to sodium fluoride gas or 

vapor are anticipated to be minimal and do not need to be assessed. In addition, the formulation 

as a wrap minimizes the potential for exposure to aerosols of sodium fluoride. Therefore, 

occupational and residential assessments are not required at this time.
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7.1.5 Human Health Incidents

There are a total of two incidents listed in the OPP Incident Data System for the period from

12/2007, when the RED was completed, to the present (search conducted on 4/28/2015). Both of 

these incidents are rated as minor. The two incidents are described below:

• In 2010, a worker experienced quarter sized burns on his forearms after applying the

product. This product also contained creosote and sodium dichromate and was cancelled

in 2004. 

• In 2012, a worker experienced respiratory symptoms after installing a pole wrap product. 

No other information was given, and it was not clear how respiratory symptoms were 

associated with the product given the low volatility of sodium flouride and the low 

potential for aerosol release from the pole wrap.

7.2 Environmental Risk Assessment

The agency has not previously conducted a risk assessment that supports a complete endangered 

species determination for sodium fluoride.

7.2.1 Environmental Fate and Exposure 

Sodium fluoride is an inorganic substance which does not undergo hydrolysis but is water 

soluble and dissociates in water to Na and F ions (EPA RED 2007). Sodium fluoride does not 

adversely affect soil biomass, microflora and macro invertebrates, and is not expected to be bioaccumulative. A field monitoring study of sodium fluoride treated poles found that sodium and 

fluoride ions occasionally exceed background levels but do not appear to migrate outward from 

treated poles more than 10 cm or more than 50 cm deep. Sodium flouride levels returned to 

background levels by the end of the 18 month study. Sodium and fluoride are present in the 

environmental media. Even if they exceed the background level from a certain use, it is a 

localized phenomenon as these ions do not move downward or laterally on the soil surface. As 

time passes, the background level is retained. Therefore, sodium fluoride is not expected to pose 

a hazard to groundwater or surface waters.

7.2.2 Ecological Risk Characterization

Considering the lack of any acute toxicity to fish and aquatic invertebrates (EPA RED 2007), any 

potential exposure to sodium fluoride through direct contact or ingestion is expected to have 

negligible toxicological effects. Sodium fluoride is not expected to move from the base of 

treated poles into surface waters, because the product is a wrap applied underground and the base 

of the pole is covered with soil after application. Monitoring has shown that any sodium fluoride 

leached from poles remains in the soil near the pole and rapidly dissociates into Na and F ions. 

The amount of dissolved residues in aquatic environments is expected to be negligible, far below 

levels that might be toxic to aquatic organisms. Therefore, exposure of aquatic plants and 

chronic exposure of fish and aquatic invertebrates is not expected.

The use of sodium fluoride as an underground pole wrap is not expected to result in any 

significant risk to terrestrial wildlife. Sodium fluoride is practically nontoxic to birds on a 

dietary basis (EPA RED 2007). Although moderately toxic to small mammals on an acute-oral 
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basis, minimal exposure is expected based on the nature and location of the product use site. 

Exposure of honey bees also is unlikely. Bioaccumulation is not expected.

7.2.3 Threatened and Endangered Species

Although a risk assessment has not been previously conducted to support a complete endangered 

species determination, there is no expectation for the registered use of the sodium fluoride woodpreservative wrap to cause direct or indirect adverse effects to threatened and endangered 

species. Also, no adverse modification of any designated critical habitat for such species is 

expected from the use of sodium fluoride as a utility pole wrap. Exposure of terrestrial species is 

unlikely, because the product is a wrap applied underground to the base of poles that are covered 

by soil after application. Aquatic species are also unlikely to be exposed, because sodium 

fluoride remains near the base of poles, rapidly dissociates into F and Na ions, and is unlikely to 

runoff or leach from the target application site into non-target areas. 

Furthermore, sodium fluoride is practically nontoxic to fish and aquatic invertebrates, is 

practically nontoxic to birds when administered in their diet, and is not expected to 

bioaccumulate.

Based on both the lack of potential exposure and sodium fluoride’s practically nontoxic effects to 

fish, aquatic invertebrates and birds, the agency has made a “no effect” (NE) determination for 

federally listed species and designated critical habitats and has concluded that consultation with 

the U.S. Fish and Wildlife Services (USFWS) and NOAA’s National Marine Fisheries Service 

(NMFS) is not required under the Endangered Species Act (ESA) section 7(a)2. EPA anticipates 

conducting no further analysis of potential risks to endangered or threatened species. 

7.2.4 Ecological Incidents

There are no fish or wildlife poisoning incidents in OPP’s Incident Data System (IDS) involving 

NaF as of April 2015.

7.3 Endocrine Disruptor Screening Program (EDSP)

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its 2007 reregistration decision for sodium fluoride, EPA reviewed 

these data and selected the most sensitive endpoints for relevant risk assessment scenarios from 

the existing hazard database. However, as required by FFDCA section 408(p), sodium fluoride

is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 
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active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and nine inert ingredients. A second list of 

chemicals identified for EDSP screening was published on June 14, 20132

2 and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither of these lists 

should be construed as a list of known or likely endocrine disruptors. 

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.33

Interim Registration Review Decision

In accordance with 40 CFR Sections 155.56 and 155.58, the agency is issuing this Interim 

Registration Review Decision document. Except for the EDSP component of the sodium fluoride 

registration review case, the agency has made the following interim decision that no additional 

data and no further risk assessments are required at this time. In addition, EPA does not expect 

sodium fluoride to have direct or indirect adverse effects to non-listed and listed species or to 

adversely modify any designated critical habitat for such species and has made a “no effect” 

determination under the ESA for all listed species and designated critical habitat for such 

species.

Next Steps and Timeline

A Federal Register Notice will announce the availability of this Interim Registration Review 

Decision for sodium fluoride. The final decision on the registration review for sodium fluoride 

(case 3132) will occur after an EDSP FFDCA section 408(p) determination has been made. See

the estimated timeline for the completion of sodium fluoride registration review in Table 2.

 2 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals.

3

http://www.epa.gov/endo/
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Table 2 – Registration Review Schedule for Sodium Fluoride

Anticipated Activity Target Date Completion Date

Interim Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Combined Preliminary 

Work Plan and Proposed Interim Decision 12-2014 12-2014

Close Public Comment Period 02-2015 02-2015

Issue Interim Decision and Begin Post Decision Follow up* 06-2015 06-2015

Total (years) 1

*A final decision on the sodium fluoride registration review case, in accordance with 40 CFR Section 155.58, will occur after an 

EDSP FFDCA section 408(p) determination has been made.
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Appendix A Toxicology Profile

Acute Toxicity for Product Labeling 

The acute toxicity database for sodium fluoride is considered complete. Sodium fluoride has a 

high order of toxicity via the oral route of exposure (Toxicity Category II) and a moderate order 

of toxicity via the dermal and inhalation routes of exposure (Toxicity Category III). Primary eye 

irritation studies classify sodium fluoride as severely irritating (Toxicity Category II) whereas 

dermal irritation studies classify sodium fluoride as a mild or slight irritant (Toxicity Category 

IV). Sodium fluoride is not a dermal sensitizer. 

Table A1 – Acute Toxicity Studies for Sodium Fluoride

Guideline No./ Study 

Type MRID No. Results Toxicity Category

870.1100/ 

Acute oral toxicity 43778501

LD50 (combined) = 105 (93-119 CL)

Male LD50 = 120 mg/kg

Female LD50 = 89 mg/kg

II

870.1200/ 

Acute dermal toxicity 43778502 LD50 > 2000 mg/kg III

870.1300/ 

Acute inhalation toxicity 43778503 LC50 = 1.00 mg/L III

870.2400/ 

Acute eye irritation 43778504 Severely irritating to unwashed eyes II

870.2500/ 

Acute dermal irritation 43778505 Slightly Irritating IV

870.2600/ 

Skin sensitization 

43778506

40866801

Buehler: Not a skin sensitizer

Not a dermal sensitizer No

No subchronic or chronic toxicological endpoints have been selected for the use of sodium 

fluoride as an impregnated pole wrap due to the determination of no exposure.
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Acute Toxicity References

40866801 Siglin, J. (1988). Delayed Contact Hypersensitivity Study in Guinea Pigs 

with Patox-Lite: Final Report: SLS Study No. 3191.8. Unpublished study 

prepared by Springborn Life Sciences, Inc. 24 p.

43778501 Wnorowski G. (1995). Acute Oral Toxicity Defined LD50 (in Rats): 

Composite NaF: Lab Project Number: 3719:P320. Unpublished study 

prepared by Product Safety Labs. 28 p.

43778502 Wnorowski G. (1995). Acute Dermal Toxicity Limit test (in Rats): 

Composite NaF: Lab Project Number: 3722:P322. Unpublished study 

prepared by Product Safety Labs. 15 p.

43778503 Wnorowski, G. (1995). Acute Inhalation Toxicity Defined LC50 (in Rats): 

Composite NaF: Lab project Number: 3724:P330. Unpublished study 

prepared by Product Safety Labs. 42p. 

43778504 Wnorowski, G. (1995). Primary Eye Irritation (in Rabbits): Composite 

NaF: Lab project Number: 3720:P324. Unpublished study prepared by 

product Safety Labs. 26 p.

43778505 Wnorowski, G. (1995). Primary Skin Irritation (in Rabbits): Composite 

NaF: Lab Project Number: 3721: P326. Unpublished study prepared by 

Product Safety Labs. 16 p. 

43778506 Wnorowski, G. (1995). Dermal Sensitization Test-Buehler Method (in 

Guinea Pigs): Composite NaF: Lab Project Number: 3723: P328. 

Unpublished study prepared by Product Safety Labs. 24 p.