![](media/image1.wmf){width="1.41875in" height="0.4979166666666667in"}
Number range CHAPTERUnited States Prevention, Pesticides EPA
738-R-06-014

Environmental Protection and Toxic Substances July 2006

Agency (7509P)

#### Reregistration

> Eligibility Decision
>
> (RED) for Inorganic
>
> Chlorates

**REREGISTRATION ELIGIBILITY**

**DECISION**

**for**

**Inorganic Chlorates**

Case No. 4049

> Approved by:
>
> \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Debra Edwards, Ph.D.
>
> Director, Special Review and
>
> Reregistration Division
>
> \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Date

**TABLE OF CONTENTS**

[**Inorganic Chlorates Reregistration Eligibility Decision Team**
v](#__RefHeading___Toc140567132)

[**Glossary of Terms and Abbreviations**
vi](#__RefHeading___Toc140567133)

[**Abstract** viii](#__RefHeading___Toc140567134)

[**I.** **Introduction** 1](#__RefHeading___Toc140567135)

[**II.** **Chemical Overview** 3](#__RefHeading___Toc140567136)

[**A.** **Regulatory History** 3](#__RefHeading___Toc140567137)

[**B.** **Chemical Identification -- Sodium Chlorate**
3](#__RefHeading___Toc140567138)

[**C.** **Use Profile** 3](#__RefHeading___Toc140567139)

[**D.** **Estimated Usage of Sodium Chlorate**
4](#__RefHeading___Toc140567140)

[**III.** **Summary of Inorganic Chlorates Risk Assessments**
6](#__RefHeading___Toc140567141)

[**A.** **Human Health Risk Assessment**
6](#__RefHeading___Toc140567142)

[**1.** **Toxicity of Sodium Chlorate** 6](#__RefHeading___Toc140567143)

[**2.** **Carcinogenicity of Sodium Chlorate**
9](#__RefHeading___Toc140567144)

[**3. Sodium Chlorate Endocrine Effects**
10](#__RefHeading___Toc140567145)

[**4.** **Metabolites and Degradates** 10](#__RefHeading___Toc140567146)

[**5.** **Dietary Exposure and Risk (Food)**
11](#__RefHeading___Toc140567147)

[**6.** **Dietary Exposure and Risks (Drinking Water)**
13](#__RefHeading___Toc140567148)

[**7.** **Residential Exposure and Risk**
17](#__RefHeading___Toc140567149)

[**8.** **Aggregate Risk** 20](#__RefHeading___Toc140567150)

[**9.** **Occupational Exposure and Risk**
21](#__RefHeading___Toc140567151)

[**B.** **Environmental Fate and Effects Risk Assessment**
27](#__RefHeading___Toc140567152)

[**1.** **Environmental Fate and Transport**
27](#__RefHeading___Toc140567153)

[**2.** **Ecological Exposure and Risk**
28](#__RefHeading___Toc140567154)

[**IV.** **Risk Management, Reregistration, and Tolerance Reassessment**
40](#__RefHeading___Toc140567155)

[**A.** **Determination of Reregistration Eligibility**
40](#__RefHeading___Toc140567156)

[**B.** **Public Comments and Responses**
40](#__RefHeading___Toc140567157)

[**C.** **Regulatory Position** 41](#__RefHeading___Toc140567158)

[**1.** **Food Quality Protection Act Findings**
41](#__RefHeading___Toc140567159)

[**2.** **Endocrine Disruptor Effects**
42](#__RefHeading___Toc140567160)

[**3.** **Cumulative Risks** 42](#__RefHeading___Toc140567161)

[**4.** **Endangered Species** 43](#__RefHeading___Toc140567162)

[**D. Tolerance Reassessment Summary** 44](#__RefHeading___Toc140567163)

[**E.** **Regulatory Rationale** 46](#__RefHeading___Toc140567164)

[**1.** **Human Health Risk Management**
46](#__RefHeading___Toc140567165)

[**2.** **Non-Target Organism (Ecological) Risk Management**
52](#__RefHeading___Toc140567166)

[**3.** **Summary of Mitigation Measures**
57](#__RefHeading___Toc140567167)

[**F.** **Other Labeling Requirements**
58](#__RefHeading___Toc140567168)

[**1.** **Endangered Species Considerations**
58](#__RefHeading___Toc140567169)

[**2.** **Spray Drift Management** 59](#__RefHeading___Toc140567170)

[**V.** **What Registrants Need to Do**
60](#__RefHeading___Toc140567171)

[**A.** **Manufacturing-Use Products** 60](#__RefHeading___Toc140567172)

[**1.** **Generic Data Requirements** 60](#__RefHeading___Toc140567173)

[**2.** **Labeling for Manufacturing-Use Products**
61](#__RefHeading___Toc140567174)

[**B.** **End-Use Products** 61](#__RefHeading___Toc140567175)

[**1.** **Additional Product-Specific Data Requirements**
61](#__RefHeading___Toc140567176)

[**2.** **Labeling for End-Use Products**
61](#__RefHeading___Toc140567177)

[**C.** **Labeling Changes Summary Table**
61](#__RefHeading___Toc140567178)

[**D.** **Existing Stocks** 61](#__RefHeading___Toc140567179)

[]{.mark}

[]{#__RefHeading___Toc140567132 .anchor}**Inorganic Chlorates
Reregistration Eligibility Decision Team**

[Biological and Economic Analysis Assessment]{.underline}

> Rafael Prieto
>
> Alan Halvorson
>
> Nicole Zinn
>
> Andrew Lee

[Environmental Fate and Effects Risk Assessment]{.underline}

> Brian Anderson
>
> Silvia Termes
>
> Jim Goodyear
>
> Stephanie Syslo

[Health Effects Risk Assessment]{.underline}

> Susan Hummel
>
> Bonnie Cropp-Kohlligian
>
> Abdullah Khasawinah
>
> Matthew Crowley
>
> Thurston Morton
>
> Gary Otakie

[Registration Support]{.underline}

Juanita Gilchrist

Jim Tompkins

[Risk Management]{.underline}

> Molly Clayton
>
> Kimberly Nesci

[Office of General Counsel]{.underline}

Erin Koch

[]{#__RefHeading___Toc140567133 .anchor}**Glossary of Terms and
Abbreviations**

a.i. Active Ingredient

aPAD Acute Population Adjusted Dose

APHIS Animal and Plant Health Inspection Service

ARTF Agricultural Re-entry Task Force

BCF Bioconcentration Factor

CDC Centers for Disease Control

CDPR California Department of Pesticide Regulation

CFR Code of Federal Regulations

ChEI Cholinesterase Inhibition

CMBS Carbamate Market Basket Survey

cPAD Chronic Population Adjusted Dose

CSFII USDA Continuing Surveys for Food Intake by Individuals

CWS Community Water System

DCI Data Call-In

DEEM Dietary Exposure Evaluation Model

DL Double layer clothing {i.e., coveralls over SL}

DWLOC Drinking Water Level of Comparison

EC Emulsifiable Concentrate Formulation

EDSP Endocrine Disruptor Screening Program

EDSTAC Endocrine Disruptor Screening and Testing Advisory Committee

EEC Estimated Environmental Concentration. The estimated pesticide
concentration in an environment, such as a terrestrial ecosystem.

EP End-Use Product

EPA U.S. Environmental Protection Agency

EXAMS Tier II Surface Water Computer Model

FDA Food and Drug Administration

FFDCA Federal Food, Drug, and Cosmetic Act

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

FOB Functional Observation Battery

FQPA Food Quality Protection Act

FR Federal Register

GL With gloves

GPS Global Positioning System

HIARC Hazard Identification Assessment Review Committee

IDFS Incident Data System

IGR Insect Growth Regulator

IPM Integrated Pest Management

RED Reregistration Eligibility Decision

LADD Lifetime Average Daily Dose

LC~50~ Median Lethal Concentration. Statistically derived concentration
of a substance expected to cause death in 50% of test animals, usually
expressed as the weight of substance per weight or volume of water, air
or feed, e.g., mg/l, mg/kg or ppm.

LCO Lawn Care Operator

LD~50~ Median Lethal Dose. Statistically derived single dose causing
death in 50% of the test animals when administered by the route
indicated (oral, dermal, inhalation), expressed as a weight of substance
per unit weight of animal, e.g., mg/kg.

LOAEC Lowest Observed Adverse Effect Concentration

LOAEL Lowest Observed Adverse Effect Level

LOC Level of Concern

LOEC Lowest Observed Effect Concentration

mg/kg/day Milligram Per Kilogram Per Day

MOE Margin of Exposure

MP Manufacturing-Use Product

MRID Master Record Identification (number). EPA\'s system of recording
and tracking studies submitted.

MRL Maximum Residue Level

N/A Not Applicable

NASS National Agricultural Statistical Service

NAWQA USGS National Water Quality Assessment

NG No Gloves

NMFS National Marine Fisheries Service

NOAEC No Observed Adverse Effect Concentration

NOAEL No Observed Adverse Effect Level

NPIC National Pesticide Information Center

NTP National Toxicology Program

NR No respirator

OP Organophosphorus

OPP EPA Office of Pesticide Programs

ORETF Outdoor Residential Exposure Task Force

PAD Population Adjusted Dose

PCA Percent Crop Area

PDCI Product Specific Data Call-In

PDP USDA Pesticide Data Program

PF10 Protections factor 10 respirator

PF5 Protection factor 5 respirator

PHED Pesticide Handler\'s Exposure Data

PHI Preharvest Interval

ppb Parts Per Billion

PPE Personal Protective Equipment

PRZM Pesticide Root Zone Model

RBC Red Blood Cell

RAC Raw Agricultural Commodity

RED Reregistration Eligibility Decision

REI Restricted Entry Interval

RfD Reference Dose

RPA Reasonable and Prudent Alternatives

RPM Reasonable and Prudent Measures

RQ Risk Quotient

RTU (Ready-to-use)

RUP Restricted Use Pesticide

SCI-GROW Tier I Ground Water Computer Model

SF Safety Factor

SL Single layer clothing

SLN Special Local Need (Registrations Under Section 24(c) of FIFRA)

STORET Storage and Retrieval

TEP Typical End-Use Product

TSH Thyroid Stimulating Hormone

TGAI Technical Grade Active Ingredient

TRAC Tolerance Reassessment Advisory Committee

TTRS Transferable Turf Residues

UF Uncertainty Factor

USDA United States Department of Agriculture

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey

WPS Worker Protection Standard

[]{#__RefHeading___Toc140567134 .anchor}**Abstract**

[]{.mark}

The Environmental Protection Agency (EPA or the Agency) has completed
the human health and environmental risk assessments for the Inorganic
Chlorates and is issuing its risk management decision and tolerance
reassessment. The risk assessments, which are summarized below, are
based on the review of the required target database supporting the use
patterns of currently registered products and additional information
received through the public docket. After considering the risks
identified in the revised risk assessments, comments received, and
mitigation suggestions from interested parties, the Agency developed its
risk management decision for uses of inorganic chlorates that pose risks
of concern. As a result of this review, EPA has determined that
inorganic chlorate-containing products are eligible for reregistration,
provided that risk mitigation measures are adopted and labels are
amended accordingly. That decision is discussed fully in this document.

Sodium chlorate is an inorganic salt herbicide that was first registered
in 1966. It is a defoliant and a desiccant that is primarily used on
cotton, but it also has other agricultural and non-agricultural uses. As
a non-selective herbicide it is used to kill grasses and weeds in
industrial and non-agricultural sites such as driveways, tennis courts,
and recreational areas. The initial risk assessment indicated some
ecological and occupational risks of concern. Risk assessments were
revised based on refinements to the assessments as well as mitigation
measures. Occupational and ecological risks resulting from
non-agricultural uses have been mitigated by reducing application rates,
as well as limiting applications of sodium chlorate to spot treatments
only. Use on rights-of-way and ditch banks will be cancelled. The Agency
may require changes to the language of the sodium chlorate label in the
future if deemed necessary under the Endangered Species Protection
Program.

[]{#__RefHeading___Toc140567135 .anchor}**I. Introduction**

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was
amended in 1988 to accelerate the reregistration of products with active
ingredients registered prior to November 1, 1984. The amended Act calls
for the development and submission of data to support the reregistration
of an active ingredient, as well as a review of all submitted data by
the U.S. Environmental Protection Agency (referred to as EPA or "the
Agency"). Reregistration involves a thorough review of the scientific
database underlying a pesticide's registration. The purpose of the
Agency's review is to reassess the potential hazards arising from the
currently registered uses of the pesticide, to determine the need for
additional data on health and environmental effects, and to determine
whether or not the pesticide meets the "no unreasonable adverse effects"
criteria of FIFRA.

On August 3, 1996, the Food Quality Protection Act (FQPA) was signed
into law. This Act amends FIFRA and the Federal Food, Drug, and Cosmetic
Act (FFDCA) to require reassessment of all existing tolerances for
pesticides in food. FQPA also requires EPA to review all tolerances in
effect on August 2, 1996, by August 3, 2006. In reassessing these
tolerances, the Agency must consider, among other things, aggregate
risks from non-occupational sources of pesticide exposure, whether there
is increased susceptibility of infants and children, and the cumulative
effects of pesticides with a common mechanism of toxicity. When a safety
finding has been made that aggregate risks are not of concern and the
Agency concludes that there is a reasonable certainty of no harm from
aggregate exposure, the tolerances are considered reassessed. EPA
decided that, for those chemicals that have tolerances and are
undergoing reregistration, tolerance reassessment will be accomplished
through the reregistration process.

Of the inorganic chlorates listed as active ingredients (*i.e.*, sodium
chlorate (073301), calcium chlorate (073302), potassium chlorate
(073303), and magnesium chlorate (530200)), only sodium chlorate is
present as an active ingredient in currently registered products. As
such, sodium chlorate is the primary focus of the reregistration
eligibility decision. Sodium chlorate is a strong oxidizer and may be
reduced to a variety of chemical species depending on the environmental
conditions. As a consequence of its reaction as an oxidant, sodium
chlorate generates reduced chloro species (i.e., chlorine in lower
oxidation states than chlorate), such as chlorite and hypochlorite.
Since chlorite is also an active ingredient and is being considered in
the chlorite/chlorine dioxide reregistration eligibility decision (case
number 4043). The Agency will not consider the tolerances for chlorate
reassessed until the assessment of chlorite is complete. As mentioned
above, FQPA requires EPA to consider available information concerning
the cumulative effects of a particular pesticide's residues and "other
substances that have a common mechanism of toxicity." Potential
cumulative effects of chemicals with a common mechanism of toxicity are
considered because low-level exposures to multiple chemicals causing a
common toxic effect by a common mechanism could lead to the same adverse
health effect as would a higher level of exposure to any one of these
individual chemicals.

EPA has not made a common mechanism of toxicity finding as to parent
sodium chlorate and any other substances, and sodium chlorate does not
appear to produce a toxic metabolite that is in common with those
produced by other substances. For the purposes of this reregistration
eligibility decision (RED), therefore, EPA has not assumed that the
inorganic chlorates have a common mechanism of toxicity with other
substances. For information regarding EPA's efforts to determine which
chemicals have a common mechanism of toxicity and to evaluate the
cumulative effects of such chemicals, see the policy statements released
by EPA's Office of Pesticide Programs concerning common mechanism
determinations and procedures for cumulating effects from substances
found to have a common mechanism on EPA's website at
http://www.epa.gov/pesticides/cumulative/.

This document presents EPA's revised human health and ecological risk
assessments, its progress toward tolerance reassessment, and the
reregistration eligibility decision for inorganic chlorates. The
document consists of six sections. Section I contains the regulatory
framework for reregistration/tolerance reassessment; Section II provides
a profile of the use and usage of the chemical; Section III gives an
overview of the human health and environmental effects risk assessments;
Section IV presents the Agency\'s decision on reregistration eligibility
and risk management; and Section V summarizes the label changes
necessary to implement the risk mitigation measures outlined in Section
IV. Finally, the Appendices list related information, supporting
documents, and studies evaluated for the reregistration decision. The
revised risk assessments for inorganic chlorates are available in the
Office of Pesticide Programs (OPP) public docket under docket number
OPP-2005-0507 available on the Agency's web page at
http://www.epa.gov/oppsrrd1/reregistration/inorganicchlorates/.

[]{#__RefHeading___Toc140567136 .anchor}**II. Chemical Overview**

Of the inorganic chlorates listed as active ingredients (*i.e.*, sodium
chlorate (073301), calcium chlorate (073302), potassium chlorate
(073303), and magnesium chlorate (530200)), only sodium chlorate is
present as an active ingredient in currently registered products. Sodium
chlorate, calcium chlorate, and potassium chlorate are present as inert
ingredients in currently registered products and exposures as a result
of those uses are addressed herein. Sodium chlorate is a
defoliant/desiccant, and is used as an herbicide.

[]{.mark}

[]{#__RefHeading___Toc140567137 .anchor}**A. Regulatory History**

[]{.mark}

Sodium chlorate was first registered in February 23, 1966 by Value
Gardens Supply, LLC, for use on both annual and perennial grasses and
weeds for the following non-agricultural use sites: garage areas, tennis
courts, curbs, driveways, walks, and patios. On October 30, 1968, Helena
Chemical Company registered it for use as a desiccant on agricultural
sites (sorghum and cotton). Currently, there are 56 active product
registrations containing sodium chlorate as an active ingredient,
including 11 technical (manufacturing use) registrations, and 45 end-use
products ranging from 2.3% to 99.7% active ingredient. Sodium chlorate
is currently manufactured by seven companies. The compound may be used
in combination with other herbicides, such as atrazine, 2,4-D, bromacil,
diuron, and sodium metaborate.

[]{#__RefHeading___Toc140567138 .anchor}**B. Chemical Identification --
Sodium Chlorate**

Chemical Structure:

![](media/image2.png)

Common Names: Sodium chlorate, soda chlorate, chloric acid, sodium salt

Chemical Name: Sodium chlorate

Trade Names: Number range CHAPTERFerti-Lome, Barespot, Tri-Kil,
Bareground, Prometon, Pramitol,

Killsall, TriChlor

Chemical Family: Inorganic salt

Case Number: 4049

CAS Number: Number range CHAPTER7775-09-9

PC Code: 073301

Molecular Weight: 106.5

Empirical Formula: Number range CHAPTERNaClO~3~

Technical Registrants: EKA Chemicals, ERCO Chemicals, Kerr-McGee
Chemical,

Nexen Chemical USA, Moore Agricultural Products Company, Inc.

[]{#__RefHeading___Toc140567139 .anchor}**C. Use Profile**

The following is information on the currently registered uses of sodium
chlorate, including an overview of use sites and application methods. A
detailed table of the uses of sodium chlorate eligible for
reregistration is available in Appendix A.

Type of Pesticide: Herbicide (desiccant/defoliant)

Target Pest: Broadleaf weeds

Mode of Action: Non-selective, contact herbicide that penetrates the
cuticle causing cell death by altering the metabolic processes.

[Use Sites]{.underline}

Agricultural uses: Agriculturally, it is primarily used on cotton;
however, it is also applied to a wide variety of other crops including,
but not limited to, rice, corn, soybeans, dry beans, potatoes,
sunflowers, flax, safflower, chili peppers (for processing only), grain
sorghum, and wheat.

Non-agricultural Uses: Sodium chlorate is used on nonagricultural
(residential and industrial) areas such as rights-of-ways, building
perimeters, ditch banks, bleachers, airport runways, vacant lots, fire
hydrants, or as a pre-paving treatment. It is also used by a small
percentage of water treatment facilities for the generation of chlorine
dioxide.

Use Classification: General Use

Formulation Types: Agricultural products are all formulated as soluble
concentrates/liquids; non-crop products are formulated as soluble
concentrates/liquids and granules or pellets/tablets.

Application Methods: Sodium chlorate as a defoliant/desiccant in
agricultural settings is applied using aerial and groundboom equipment.
As an herbicide in nonagricultural settings, it is applied using
handheld equipment such as a low-pressure handwands or sprinkling cans;
it is also applied via groundboom or handgun sprayer application methods
for larger commercial scenarios. Granular formulations can be applied
using belly grinders, push-type spreaders, tractor-drawn spreaders, or
by hand.

Application Rates: In agriculture, rates range from 6 pounds active
ingredient per acre (6 lb ai/A) to 12.5 lbs ai/A. Industrial and other
noncrop site rates range from 132 to 1032 lbs ai/A, based on current
labels. Sodium chlorate can be applied multiple times per year.

Application Timing: Sodium chlorate is applied post-emergence.

[]{#__RefHeading___Toc140567140 .anchor}**D. Estimated Usage of Sodium
Chlorate**

The primary non-pesticidal use for sodium chlorate is as a precursor in
chlorine dioxide generation through a closed system to bleach wood
pulp/paper. The pesticidal uses of sodium chlorate, including the
agricultural uses as a defoliant/desiccant, are a small percentage
(approximately 2%) of the total sodium chlorate used in the United
States. According to Agency data, approximately 2.8 million pounds of
sodium chlorate are applied annually to agricultural, residential, and
commercial use sites. A screening-level usage analysis (SLUA) of sodium
chlorate from 1998 to 2005 indicates that approximately 2.1 million
pounds of sodium chlorate are used annually on agricultural use sites in
the United States. In terms of pounds applied, the greatest use is on
cotton (1.9 million lbs ai per year); annually this represents
approximately 5 percent of cotton acreage treated.

Exposure to the chlorate may also occur as a result of the drinking
water disinfection process. This use and resulting exposure are
explained in detail in this document.

[]{#__RefHeading___Toc140567141 .anchor}**III. Summary of Inorganic
Chlorates Risk Assessments**

The following is a summary of EPA's revised human health and ecological
risk assessments for inorganic chlorates, as presented fully in the
documents, revised *Inorganic Chlorates. HED Chapter of the
Reregistration Eligibility Decision Document (RED)*, dated January 26,
2006, and the revised *Sodium Chlorate Ecological Risk Assessment,*
dated June 1, 2006. The purpose of this summary is to assist the reader
by identifying the key features and findings of these risk assessments,
and to help the reader better understand the conclusions reached in the
assessments.

The human health and ecological risk assessment documents and supporting
information listed in Appendix C were used to reach the safety finding
and regulatory decision for sodium chlorate. While the risk assessments
and related addenda are not included in this document, they are
available from the OPP Public Docket, located at
[http://www.regulations.gov](http://www.regulations.gov/), under docket
number EPA-HQ-OPP-2005-0507.

EPA\'s use of human studies in the sodium chlorate risk assessment is in
accordance with the Agency\'s Final Rule promulgated on January 26,
2006, related to Protections for Subjects in Human Research, which is
codified in 40 CFR Part 26.

[]{#__RefHeading___Toc140567142 .anchor}**A. Human Health Risk
Assessment**

The human health risk assessment incorporates potential exposure,
hazard, and risks from all sources, which include food, drinking water,
residential (if applicable), and occupational scenarios. Aggregate
assessments combine food, drinking water, and any residential or other
non-occupational (if applicable) exposures to determine potential
exposures to the U.S. population. The Agency's human health assessment
considers all U.S. populations, including infants and young children.
For more information on the inorganic chlorates human health risk
assessment, see *Revised Inorganic Chlorates. HED Chapter of the
Reregistration Eligibility Decision Document (RED)* dated June 26, 2006.

[]{#__RefHeading___Toc140567143 .anchor}**1. Toxicity of Sodium
Chlorate**

Toxicity assessments are designed to predict whether a pesticide could
cause adverse health effects in humans (including short-term or acute
effects such as skin or eye damage, and lifetime or chronic effects such
as cancer, developmental effects, or reproductive effects), and the
level or dose at which such effects might occur. The Agency has reviewed
all toxicity studies submitted for sodium chlorate and has determined
that the toxicological database is complete, reliable, and sufficient
for reregistration. For more details on the toxicity and carcinogenicity
of the inorganic chlorates, see *Revised Inorganic Chlorates. HED
Chapter of the Reregistration Eligibility Decision Document (RED)* dated
January 26, 2006, which is available under docket number
EPA-HQ-OPP-2005-0507.

**a. Acute Toxicity Profile**

In acute toxicity tests, sodium chlorate is slightly toxic by the oral
(Toxicity Category IV), dermal (Toxicity Category III), and inhalation
routes (Toxicity Category IV). Sodium chlorate crystals were mildly
irritating to the rabbit eye (Toxicity Category III), and were a minimal
to mild dermal irritant (Toxicity Category III). Incident reports show
that ingestion of toxic doses of sodium chlorate by humans produces
gastritis, hemolysis, methemoglobinemia, hemoglobinurea, late toxic
nephritis, and acute renal failure. Doses in excess of 100 mg/kg are
generally fatal to humans. The acute toxicity profile for sodium
chlorate is summarized in Table 1 below.

+------------+------------------+-------+---------------+------------+
| **Table 1. |                  |       |               |            |
| Acute      |                  |       |               |            |
| Toxicity   |                  |       |               |            |
| Profile -  |                  |       |               |            |
| Sodium     |                  |       |               |            |
| Chlorate** |                  |       |               |            |
+------------+------------------+-------+---------------+------------+
| *          | **Study Type**   | *     | **Results**   | **Toxicity |
| *Guideline |                  | *MRID |               | Cat        |
| Number**   |                  | No.** |               | egory^a^** |
+------------+------------------+-------+---------------+------------+
| 870.1100   | Acute oral -Rats | 418   | LD~50~ ≥5000  | IV         |
|            |                  | 19901 | mg/kg (rat)   |            |
+------------+------------------+-------+---------------+------------+
| 870.1200   | Acute dermal -   | 424   | LD~50~ = \>   | III        |
|            | Rabbits          | 97601 | 2000 mg/kg    |            |
+------------+------------------+-------+---------------+------------+
| 870.1300   | Acute            | 418   | LC~50~ = 5.59 | IV         |
|            | inhalation -     | 19903 | mg/L          |            |
|            | Rats             |       |               |            |
+------------+------------------+-------+---------------+------------+
| 870.2400   | Acute eye        | 000   | mildly        | III        |
|            | irritation -     | 85090 | irritating    |            |
|            | Rabbit           | 001   |               |            |
|            |                  | 02998 |               |            |
|            |                  |       |               |            |
|            |                  | 418   |               |            |
|            |                  | 19904 |               |            |
+------------+------------------+-------+---------------+------------+
| 870.2500   | Acute dermal     | 424   | minimally     | III        |
|            | irritation -     | 97602 | irritating    |            |
|            | Rabbit           |       |               |            |
+------------+------------------+-------+---------------+------------+
| 870.2600   | Skin             | 418   | not a dermal  | NA         |
|            | sensitization -  | 19906 | sensitizer    |            |
|            | guinea pigs      |       |               |            |
+------------+------------------+-------+---------------+------------+

a\. The technical acute toxicity values included in this document are
for informational purposes only. The data supporting these values may or
may not meet the current acceptance criteria.

**b. FQPA Safety Factor Considerations**

The Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the Food
Quality Protection Act (FQPA), directs the Agency to use an additional
ten fold (10x) safety factor (SF) to account for potential pre- and
postnatal toxicity and completeness of the data with respect to exposure
and toxicity to infants and children. FQPA authorizes the Agency to
modify the 10x FQPA SF only if reliable data demonstrate that the
resulting level of exposure would be safe for infants and children.

For sodium chlorate, based on the hazard data and the exposure data,
tNumber range CHAPTERhe FQPA SF was reduced to 1x. There was no pre- or
postnatal sensitivity or susceptibility observed in the submitted
developmental studies in rats and rabbits or the 2-generation
reproduction study in rats. However, there is a concern for developing
offspring because of the effects of inorganic chlorate on thyroid
function in rats. The thyroid hormone system plays a critical role in
development, and it is therefore important to understand whether the
thyroid hormone system in the developing young differs in response to
thyroid toxicants compared to adults. There exists, therefore, an
uncertainty regarding information on comparative thyroid response in
young versus (vs.) adult rats; however, a SF reflecting the uncertainty
in comparative response is not necessary and the 10x FQPA SF can be
removed (reduced to 1x).

The rationale for removal of the FQPA SF lies in the comparative thyroid
physiology of rats vs. humans. As a consequence of these dynamic
differences, rats are much more sensitive to thyroid toxicants, such as
chlorate, than humans and non-human primates. As discussed in the
section below, the chronic reference dose (RfD) for inorganic chlorates
is 0.03 mg/kg/day based on thyroid hypertrophy in adult rats. There is a
study of the effects of chlorate on adult monkeys, in which the no
observed adverse effects level (NOAEL) for effects on blood thyroxine
levels was 58 mg/kg/day. If the NOAEL from the monkey study were used to
derive a chronic RfD with uncertainty factors of 10x for interspecies
extrapolation and 10X for intraspecies variability, and an FQPA SF of
10x reflecting uncertainties in effects to the young, the chronic RfD
would be 0.06 mg/kg/day. The chronic RfD selected by the risk assessment
team of 0.03 mg/kg/day derived from a chronic rat study, conducted by
the National Toxicology Program (NTP), is therefore protective of
thyroid effects in primates (including a 10X factor for uncertainty with
respect to developing young) without the necessity of an additional
uncertainty factor applied to the rat data.

In addition, the moderately refined dietary food assessment uses field
trial data and percent crop treated estimates for all commodities, and
the residential exposure assessment is based on reliable data; as such,
exposure will not be underestimated. The dietary drinking water
assessment uses residues in finished drinking water collected from water
treatment facilities, which use chlorine dioxide or hypochlorite to
treat drinking water. See *Revised Inorganic Chlorates. HED Chapter of
the Reregistration Eligibility Decision Document (RED)* dated January
26, 2006, for additional details.

c.  **Toxicological Endpoints**

The toxicological endpoints used in the human health risk assessment for
sodium chlorate are listed in Table 2 below. Although several studies
were considered, an acute reference dose (aRfD) was not identified. None
of the available studies provided an endpoint of toxicity attributable
to a single exposure.

Sodium chlorate is unlikely to be absorbed by the skin based on its high
water solubility and ionic nature; therefore, a risk assessment for
dermal exposure is not needed and a dermal endpoint was not selected.
For inhalation absorption, a default factor of 100% was used since, per
Agency policy, the inhalation dose was derived from an oral endpoint.

The usual interspecies uncertainty factor is 10x, but there are several
important quantitative dynamic differences between rats and humans with
respect to thyroid function that permit an interspecies factor of less
than 10x for a thyroid toxicant like sodium chlorate. The half-life of
thyroid hormone T4 in rats is approximately 12 hours, whereas in humans,
the half-life is 5-9 days. The shorter half-life in rats is likely
related to a high-affinity binding globulin for thyroxin that is present
in humans, but absent in rodents. In the absence of a functional thyroid
gland, a rat requires approximately 10-times more T4 than an adult human
for full reconstitution. Constitutive thyroid stimulating hormone (TSH)
levels are nearly 25-times higher in rats than in humans, reflecting the
increased activity of the thyroid-pituitary axis in rats. Therefore, the
10x interspecies factor can be reduced to 3x based on dynamic
considerations. The uncertainty factors (UF) and safety factors used to
account for interspecies extrapolation, intraspecies variability, and
susceptibility of infants and children (FQPA SF) are also described in
Table 2.

+-----------+---------------+---------------+------------------------+
| **Table   |               |               |                        |
| 2.        |               |               |                        |
| Summary   |               |               |                        |
| of        |               |               |                        |
| Toxi      |               |               |                        |
| cological |               |               |                        |
| Doses and |               |               |                        |
| Endpoints |               |               |                        |
| for       |               |               |                        |
| Chlorate  |               |               |                        |
| *per se*  |               |               |                        |
| for Use   |               |               |                        |
| in Human  |               |               |                        |
| Risk      |               |               |                        |
| As        |               |               |                        |
| sessments |               |               |                        |
| for       |               |               |                        |
| Inorganic |               |               |                        |
| Ch        |               |               |                        |
| lorates** |               |               |                        |
+===========+===============+===============+========================+
| *         | **Dose,       | **FQPA Safety | **Study and Endpoint   |
| *Exposure | Uncertainty   | Factor and    | for Risk Assessment**  |
| S         | Factors**     | Level of      |                        |
| cenario** |               | Concern**     |                        |
+-----------+---------------+---------------+------------------------+
| Acute     | Acute RfD=    | Although      |                        |
| Dietary   | not           | several       |                        |
|           | applicable    | studies were  |                        |
|           |               | considered,   |                        |
|           |               | an acute      |                        |
|           |               | reference     |                        |
|           |               | dose (aRfD)   |                        |
|           |               | was not       |                        |
|           |               | identified.   |                        |
|           |               | None of the   |                        |
|           |               | available     |                        |
|           |               | studies       |                        |
|           |               | provided an   |                        |
|           |               | endpoint of   |                        |
|           |               | toxicity      |                        |
|           |               | attributable  |                        |
|           |               | to a single   |                        |
|           |               | exposure.     |                        |
+-----------+---------------+---------------+------------------------+
| Chronic   | BMDL^1^ = 0.9 | FQPA SF = 1X  | Chronic Study in rats  |
| Dietary   | mg/kg/day     |               | (NTP, 2004).           |
|           |               | cPAD =        |                        |
| (all      | UF = 30 (3x   | [Chronic      | The LOAEL= 5 mg/kg/day |
| pop       | interspecies  | RfD           | based on increased     |
| ulations) | and 10x       | ]{.underline} | thyroid gland          |
|           | intraspecies) |               | follicular cell        |
|           |               | FQPA SF       | hypertrophy and        |
|           | Chronic RfD = |               | follicular cell        |
|           | 0.03          | cPAD= 0.03    | mineralization.        |
|           | mg/kg/day     | mg/kg/day     |                        |
+-----------+---------------+---------------+------------------------+
| Short-    | Oral NOAEL    | FQPA SF = 1X  | Subchronic study in    |
| and       | =30 mg/kg/day |               | rats McCauley *et al*, |
| Intermed  |               | Residential   | 1995. Pituitary        |
| iate-Term | UF = 100      | LOC for MOE   | effects                |
| I         |               | =100          | (vacuolization) and    |
| ncidental |               |               | thyroid gland effects  |
| Oral      |               |               | (colloid depletion),   |
|           |               |               | body weight decrease   |
|           |               |               | and organ weight       |
|           |               |               | changes and reduction  |
|           |               |               | in erythrocyte counts  |
|           |               |               | and hemoglobin content |
|           |               |               | at the LOAEL of 100    |
|           |               |               | and 150 mg/kg/day in   |
|           |               |               | males and females,     |
|           |               |               | respectively           |
+-----------+---------------+---------------+------------------------+
| Short-,   | Not           | Dermal        |                        |
| Inter     | applicable    | absorption is |                        |
| mediate-, |               | unlikely due  |                        |
| and       |               | to the ionic  |                        |
| Long-Term |               | nature and    |                        |
| Dermal    |               | water         |                        |
|           |               | solubility of |                        |
|           |               | sodium        |                        |
|           |               | chlorate      |                        |
+-----------+---------------+---------------+------------------------+
| Short-,   | NOAEL =30     | FQPA SF = 1X  | McCauley *et al*, 1995 |
| Inter     | mg/kg/day^2^  |               |                        |
| mediate-, |               | Residential   |                        |
| and       | UF = 100      | LOC for MOE   |                        |
| Long-Term |               | =100          |                        |
| I         |               |               |                        |
| nhalation |               | Occupational  |                        |
|           |               | LOC for MOE   |                        |
|           |               | =100          |                        |
+-----------+---------------+---------------+------------------------+
| Cancer    | Cl            |               |                        |
| (Oral,    | assification: |               |                        |
| dermal,   | Not likely to |               |                        |
| in        | be            |               |                        |
| halation) | carcinogenic  |               |                        |
|           | to humans at  |               |                        |
|           | doses that do |               |                        |
|           | not alter     |               |                        |
|           | thyroid       |               |                        |
|           | hormone       |               |                        |
|           | homeostasis.  |               |                        |
+-----------+---------------+---------------+------------------------+
| UF =      |               |               |                        |
| un        |               |               |                        |
| certainty |               |               |                        |
| factor,   |               |               |                        |
| FQPA SF = |               |               |                        |
| FQPA      |               |               |                        |
| safety    |               |               |                        |
| factor,   |               |               |                        |
| NOAEL =   |               |               |                        |
| no        |               |               |                        |
| observed  |               |               |                        |
| adverse   |               |               |                        |
| effect    |               |               |                        |
| level,    |               |               |                        |
| LOAEL =   |               |               |                        |
| lowest    |               |               |                        |
| observed  |               |               |                        |
| adverse   |               |               |                        |
| effect    |               |               |                        |
| level,    |               |               |                        |
| PAD =     |               |               |                        |
| p         |               |               |                        |
| opulation |               |               |                        |
| adjusted  |               |               |                        |
| dose (a = |               |               |                        |
| acute, c  |               |               |                        |
| =         |               |               |                        |
| chronic), |               |               |                        |
| RfD =     |               |               |                        |
| reference |               |               |                        |
| dose, MOE |               |               |                        |
| = margin  |               |               |                        |
| of        |               |               |                        |
| exposure, |               |               |                        |
| LOC =     |               |               |                        |
| level of  |               |               |                        |
| concern,  |               |               |                        |
| NA = Not  |               |               |                        |
| A         |               |               |                        |
| pplicable |               |               |                        |
|           |               |               |                        |
| 1\. A     |               |               |                        |
| NOAEL was |               |               |                        |
| not       |               |               |                        |
| i         |               |               |                        |
| dentified |               |               |                        |
| in this   |               |               |                        |
| study.    |               |               |                        |
| Therefore |               |               |                        |
| a bench   |               |               |                        |
| mark dose |               |               |                        |
| (BMD)     |               |               |                        |
| analysis  |               |               |                        |
| was       |               |               |                        |
| performed |               |               |                        |
| and a     |               |               |                        |
| BMDL of   |               |               |                        |
| 28 mg     |               |               |                        |
| sodium    |               |               |                        |
| c         |               |               |                        |
| hlorate/L |               |               |                        |
| (22 mg    |               |               |                        |
| ch        |               |               |                        |
| lorate/L) |               |               |                        |
| was       |               |               |                        |
| ca        |               |               |                        |
| lculated. |               |               |                        |
| This      |               |               |                        |
| co        |               |               |                        |
| rresponds |               |               |                        |
| to 0.9 mg |               |               |                        |
| chlora    |               |               |                        |
| te/kg/day |               |               |                        |
| oral      |               |               |                        |
| dose.     |               |               |                        |
|           |               |               |                        |
| 2\. A     |               |               |                        |
| 100%      |               |               |                        |
| i         |               |               |                        |
| nhalation |               |               |                        |
| a         |               |               |                        |
| bsorption |               |               |                        |
| factor is |               |               |                        |
| used for  |               |               |                        |
| extr      |               |               |                        |
| apolating |               |               |                        |
| from an   |               |               |                        |
| oral      |               |               |                        |
| endpoint  |               |               |                        |
| of        |               |               |                        |
| toxicity. |               |               |                        |
+-----------+---------------+---------------+------------------------+

[]{#__RefHeading___Toc140567144 .anchor}**2. Carcinogenicity of Sodium
Chlorate**

Sodium chlorate is a thyroid toxicant producing thyroid gland follicular
cell hypertrophy in rats and mice following chronic exposures. The
Agency classified sodium chlorate as not likely to be carcinogenic to
humans at doses that do not alter thyroid hormone homeostasis in
accordance with the EPA policy, *Assessment of Thyroid Follicular Cell
Tumors,* dated March 1998. This policy states that nonmutagenic
pesticides that induce elevated levels of TSH and thyroid follicular
cell tumors in the rat are classified as not likely to be carcinogenic
to humans at doses that do not alter thyroid hormone homeostasis.

The preliminary results of a draft 2-year National Toxicology Program
(NTP) bioassay study on sodium chlorate to determine the potential of
this chemical to induce tumors in laboratory animals (rats and mice)
(NTP, 2004) showed evidence of thyroid gland follicular cell hyperplasia
and follicular cell tumors in male rats. The effects may be attributed
to changes in levels of thyroid hormones seen after administration of
high doses of sodium chlorate. A final study report is expected later
this year. In female mice there was equivocal and marginal evidence of
increased pancreatic islet carcinoma. Sodium chlorate was negative in
most bacterial gene mutation assays and in several cytogenetics tests,
including a hypoxanthine-guanine phosphoribosyl-transferase (HGPRT)
assay in Chinese hamster ovaries and a micronucleus assay.

The Agency selected aNumber range CHAPTER chronic endpoint based on the
thyroid effects from the NTP bioassay study using a benchmark dose
analysis approximation of the NOAEL. This endpoint is protective for all
populations, including children because children are not expected to be
more susceptible to chlorate-induced thyroid effects than adults.
Therefore, the current chronic risk assessments presented in this
document are protective of any cancer-related effects for all
populations. For more information, see the document *Revised Inorganic
Chlorates. HED Chapter of the Reregistration Eligibility Decision
Document (RED)* dated January 26, 2006.

[]{#__RefHeading___Toc140567145 .anchor}**3. Sodium Chlorate Endocrine
Effects**

The EPA is required under the FFDCA, as amended by FQPA, to develop a
screening program to determine whether certain substances (including
pesticides active and other ingredients) "may have an effect in humans
similar to an effect produced by a naturally occurring estrogen, or
other such endocrine effects as the Administrator may designate."
Following recommendations of its Endocrine Disruptor and Testing
Advisory Committee (EDSTAC), EPA determined that there was a scientific
basis for including, as part of the program, the androgen and thyroid
hormone systems, in addition to the estrogen hormone system.

The available toxicity studies on sodium chlorate demonstrate the
thyroid gland to be its target of toxicity. The endpoints selected to
assess chronic dietary risk and short- and intermediate-term oral and
inhalation risks in this document are protective of the observed thyroid
effects seen in the available toxicity studies. When additional
appropriate screening and/or testing protocols being considered under
the Agency's Endocrine Screening Disruption Program have been developed,
sodium chlorate may be subject to further screening and/or testing to
better characterize effects related to endocrine disruption.

[]{#__RefHeading___Toc140567146 .anchor}**4. Metabolites and
Degradates**

The Agency reviewed the metabolism of the inorganic chlorates, and
concluded that there are several residues of concern in food. In plants,
the terminal residues of sodium chlorate in/on plants are likely
chlorate (ClO~3~^-^), chlorite (ClO~2~^-^), and chloride (Cl^-^). Based
on published rat metabolism data, terminal residues of sodium chlorate
in animal tissues are also expected to be chlorate (ClO~3~^-^), chlorite
(ClO~2~^-^), and chloride (Cl^-^).

In the environment, because chlorate is a strong oxidizing agent
(oxidation state V), it gets reduced to chlorine species in lower
oxidation states, such as the oxyanions chlorite (ClO~2~^-^, oxidation
state III) and hypochlorite (ClO^-^, oxidation state I), chlorine
dioxide (oxidation state IV), and chloride (oxidation state -I). Thus,
at least some, and possibly a substantial, reduction of the chlorate
resulting from the application of sodium chlorate is likely to occur in
the field prior to any runoff to surface water. Under environmental
(terrestrial field) redox conditions, and based on chemical equilibria
alone, the thermodynamically favored, end reduction product of chlorate
in soil and in water is the chloride anion. Any intermediate chlorine
dioxide that may form under environmental conditions will undergo
photochemical reactions when exposed to sunlight. The chlorine
oxyanions, chlorite and hypochlorite (other possible more reduced
intermediates in the ultimate reduction of chlorate to chloride), are
strong oxidizers in themselves; thus, they are also reduced and/or
undergo disproportionation reactions. Although reduction reactions of
chlorate, chlorite, and hypochlorite are said to occur very fast, how
fast they occur is not known (*i.e.*, the actual rate constants in the
environment are not known). Therefore, at any given time the
distribution of reduced species (type and concentration) cannot be
estimated. However, it is unlikely that a single reduced species would
be present. Chlorite is being considered in the chlorite/chlorine
dioxide reregistration eligibility decision (case number 4043). (See
*Revised Inorganic Chlorates. HED Chapter of the Reregistration
Eligibility Decision Document (RED)* dated January 26, 2006, for
additional details.)

[]{#__RefHeading___Toc140567147 .anchor}**5. Dietary Exposure and Risk
(Food)**

Number range CHAPTER Number range CHAPTERDietary exposure (food only) to
inorganic chlorates as the chlorate ion (ClO~3~^-^) may be expected from
the following dietary exposure routes: 1) from sodium chlorate as an
active ingredient in conventional (agricultural) pesticides used on food
crops; 2) from sodium chlorate and potassium chlorate as inert
ingredients in conventional pesticides used on food crops or in poultry
premises; 3) from secondary residues in meat/milk/poultry/eggs due to
residues in animal feedstuffs; 4) from sodium chlorate and calcium
chlorate as inert ingredients in antimicrobial agents used as fruit,
vegetable, and egg sanitizing washes, as treatments to mushrooms to
control bacterial blotch, as treatments to seed used for sprouting, for
conditioning live oysters, in poultry drinking water, in fish filleting,
and in pecan cracking/dyeing; and 5) as a potential redox of chlorine
dioxide and sodium chlorite in conventional and antimicrobial
pesticides; (6) from degradation of hypochlorites in antimicrobial
agents used as fruit and vegetable washes; and, (7) from translocation
of very small amounts of chlorate ion (ClO~3~^-^) by plants
(translocation of significant amounts would be phytotoxic to plants)
from the environment which may be present as a result of inorganic
chlorate pesticide uses.

No acute dietary endpoint was selected because effects attributable to a
single dose were not seen in the available data. Chronic and cancer
dietary analyses were conducted for the general U.S. population and
various population subgroups. Number range CHAPTER

**a. Exposure Assumptions**

Number range CHAPTERA chronic dietary risk assessment was conducted
using the Dietary Exposure Evaluation Model software with the Food
Commodity Intake Database (DEEM-FCID™, Version 2.03), which uses food
consumption data from the USDA's Continuing Surveys of Food Intakes by
Individuals (CSFII) from 1994-1996 and 1998. Number range CHAPTERNo food
monitoring data are available for this risk assessment; therefore,
exposure estimates in food were based on field trial data or, in the
case of fruit/vegetable/other washes, were derived from a film thickness
model. No chemical-specific livestock metabolism or feeding data are
available; exposure estimates in meat, milk, poultry, and eggs were
derived from rat metabolism data, field trial data, and livestock
reference information concerning feed consumption, tissue weights, and
milk production. Default concentration factors (no chemical-specific
processing data are available) and the effects of washing after foliar
treatments were also incorporated into the risk assessment. Percent crop
treated data were used in this analysis. Exposures were single point
estimates; no residue decline was utilized.

**b. Population Adjusted Dose**

A population adjusted dose, or PAD, is the reference dose (RfD) adjusted
for the FQPA SF. A risk estimate that is less than 100% of the acute PAD
(aPAD), the dose at which an individual could be exposed over the course
of a single day and no adverse health effects would be expected, does
not exceed EPA's level of concern. Likewise, a risk estimate that is
less than 100% of the chronic PAD (cPAD), the dose at which an
individual could be exposed over the course of a lifetime and no adverse
health effects would be expected, does not exceed EPA's level of
concern.

**c. Acute Dietary Risk (Food)**

No acute dietary endpoint was selected because effects attributable to a
single dose were not seen in the available data; therefore, an acute
dietary risk assessment was not conducted.

**d. Number range CHAPTERChronic Dietary Risk (Food)**

A chronic (non-cancer) dietary risk assessment was conducted for all
potential chlorate dietary exposure routes using food consumption data
from 1994-1996 and 1998. The chronic dietary exposure and risk estimates
resulting from food intake were determined for the general U.S.
population and various population subgroups.

The chronic (non-cancer) dietary (food only) risk is below the Agency's
level of concern for the general US population and all population
subgroups. The most likely highest exposed population subgroup, children
1-2 years of age, was at 28% of the cPAD. See Table 3 below for details.

  -----------------------------------------------------------------------------
  **Table 3. Results                                        
  of Chronic Dietary                                        
  (Food only) Exposure                                      
  Analysis**                                                
  -------------------- --------------- -------------------- -------------------
  **Population         **cPAD          **Exposure           **% cPAD**
  Subgroup**           (mg/kg/day)**   (mg/kg/day)**        

  All populations      0.03            0.002730             9

  All infants (\< 1                    0.004511             15
  year old)                                                 

  Children 1-2 years                   0.008376             28
  old                                                       

  Children 3-5 years                   0.006906             23
  old                                                       
  -----------------------------------------------------------------------------

A cancer dietary risk assessment was conducted for all potential
chlorate dietary exposure routes, using the same dietary (food only)
exposure estimates used in the chronic (non-cancer) dietary risk
assessment for the US population. As discussed above, sodium chlorate is
a thyroid toxicant producing thyroid gland follicular cell hypertrophy
in rats and mice following chronic exposures, and may be producing
follicular cell tumors in rats. The lack of mutagenicity indicates that
the thyroid tumors are induced by a non-mutagenic mechanism. Children
are not expected to be more susceptible to chlorate-induced thyroid
effects than adults, and the endpoint selected for the thyroid effects
is protective for all populations, including children. Therefore, as
shown in Table 3 above, the chronic (food only) dietary risk assessment
is protective for cancer for the general US population, since the
estimated risk does not exceed 100% of the cPAD.

[]{#__RefHeading___Toc140567148 .anchor}**6. Dietary Exposure and Risks
(Drinking Water)**

Drinking water exposure to pesticides can occur through surface and
groundwater contamination. Number range CHAPTERChronic dietary (water
only) risk assessments were conducted using DEEM-FCID™ Version 2.03 and
drinking water consumption data from the USDA's CSFII from 1994-1996 and
1998. Exposures were single point estimates; no residue decline was
utilized.

Drinking water exposure can result from several different uses for
sodium chlorate. Agriculturally, sodium chlorate is used as a defoliant
and dessicant, primarily on cotton; however, it is also applied to a
wide variety of other crops including, but not limited to, rice, corn,
soybeans, dry beans, potatoes, sunflowers, flax, safflower, chili
peppers (for processing only), grain sorghum, and wheat. As a
non-selective herbicide, it is applied to industrial/non-crop areas such
as rights-of-ways, building perimeters, ditch banks, bleachers, airport
runways, vacant lots, fire hydrants, or as a pre-paving treatment.
Sodium chlorate is also used to generate chlorine dioxide, which is then
used to bleach wood pulp/paper and, in some cases, treat drinking water.
All of these uses could result in chlorate reaching water systems.
However, the majority of chlorate in drinking water is a result of
drinking water disinfection treatment practices.

In the US, there are two primary methods of drinking water treatment.
The first method is the generation of chlorine dioxide. In the second
method, either gaseous chlorine or hypochlorite is used to produce free
chlorine. Each of these methods, except the use of gaseous chlorine,
produce chlorate as a disinfection byproduct (DBP). The American Water
Works Association (AWWA) Disinfection Systems Committee tracks
disinfection practices in US community water systems. AWWA's most recent
comprehensive survey (completed in 1998) estimated that, of all
community water systems (CWS), approximately 20% of CWSs serving
populations greater than 10,000 use sodium hypochlorite (2% generated it
on-site), 8% use chlorine dioxide, and \<1% use calcium hypochlorite.
For CWSs using groundwater and serving populations less than 10,000, the
survey estimated that approximately 34% use sodium hypochlorite, none
use chlorine dioxide, and at least 4.5% use calcium hypochlorite. For
CWSs using surface water and serving less than 10,000, the survey
estimated that 17% use sodium hypochlorite, 6% use chlorine dioxide, and
9% use calcium hypochlorite.

For chlorine dioxide generation, both sodium chlorate and sodium
chlorite are used as precursor materials, and both typically result in
chlorate byproduct in finished drinking water. Sodium chlorite is more
commonly used than sodium chlorate. The free chlorine disinfection
process involves the use of either gaseous chlorine, or sodium or
calcium hypochlorite, as precursor materials. Historically, gaseous
chlorine has far more widely been used than hypochlorite to produce free
chlorine. In recent years, primarily as a result of various homeland
security measures, many drinking water systems are switching from
gaseous chlorine to hypochlorite. While the use of gaseous chlorine does
not result in chlorate byproduct in finished drinking water, the use of
either sodium or calcium hypochlorite can produce chlorate byproduct,
and this will be discussed in greater detail later in this section.

[Chlorine Dioxide]{.underline}

The use of chlorine dioxide can introduce chlorate into the finished
water by several routes. Drinking water plants generally use sodium
chlorite as a starting material (*i.e.,* feedstock) in the production of
chlorine dioxide. Chlorate ion may be present as a contaminant in the
sodium chlorite feedstock (usually less than four percent of the active
chlorite is chlorate). A typical range of chlorate carryover to the
finished water from chlorite feedstock contamination is about 50 µg/L
for a 1 mg/L dose of chlorine dioxide. Technology to generate chlorine
dioxide using sodium chlorate is now available to the drinking water
industry, which introduces the possibility of chlorate carryover to the
finished water from the chlorate feedstock. However, since this method
is more technically complicated than the method used with sodium
chlorite, sodium chlorite is far more commonly used in the generation of
chlorine dioxide than sodium chlorate.

Chlorate ion (ClO~3~^-^) may also be produced due to inefficient
generation of chlorine dioxide. Excess chlorine will favor the
production of chlorate over chlorine dioxide, as will keeping the
generator mixtures at highly alkaline (pH \> 11) or acidic (pH \< 3)
conditions. If the concentrations of feedstock reactants are too low, or
too much dilution water is added during the reaction, chlorate formation
is also favored.

Chlorite ion (ClO~2~^-^) is a major degradation product resulting from
the reaction of chlorine dioxide with inorganic and organic constituents
in the water. When free chlorine is used after the application of
chlorine dioxide in the treatment process, chlorite is oxidized to
chlorate. This conversion will continue over time as the water travels
through the distribution system. Chlorate ion is also formed by
photodecomposition of chlorine dioxide when treated water is exposed to
bright sunlight in open basins.

There are ways that water systems can control the levels of chlorate in
drinking water, and these will be discussed in Section 4 of this
document.

[Hypochlorite]{.underline}

Chlorine-based disinfectants, such as free chlorine, are also used by
drinking water treatment systems to treat drinking water. Some of these
water systems use sodium hypochlorite or calcium hypochlorite as their
source of free chlorine. Chlorate ion can be formed in these products
during the manufacturing process, but the decomposition of hypochlorite
solutions during storage is the more significant source of chlorate ion
in systems using hypochlorite.

Chlorate ion concentrations increase between the time of manufacture and
delivery to the water plant. The rate at which hypochlorite ion
disproportionates to chlorate is influenced by concentration of
hypochlorite, pH, and temperature. As with the chlorine dioxide methods,
there are several ways that water systems using hypochlorite can control
the levels of chlorate; these will be discussed in Section 4 of this
document.

a.  **Drinking Water Exposure**

Data on the occurrence of chlorate ion in drinking water were available
from two primary sources: 1) the Information Collection Rule (ICR)
Auxiliary 1 Database, Version 5.0, and 2) the American Water Works
Association Research Foundation (AwwaRF) study on the control of
chlorate ion in hypochlorite solutions. The ICR data is the more
extensive data set, and the water systems represented in the ICR
database serve 60% of the total US population. The EPA Office of Water
(OW) issued the ICR in order to collect data to support future
regulation of microbial contaminants, disinfectants, and disinfection
byproducts. Monitoring for chlorate was included in the ICR, since
chlorate is a disinfection byproduct. Source water and drinking water
were monitored for chlorate ion between July 1997 and December 1998.
Water systems serving a population of at least 100,000 were required to
monitor for chlorate ion at treatment plants using chlorine dioxide or
hypochlorite solutions in the treatment process. Plants using chlorine
dioxide collected monthly samples of the source water entering the
plant, the finished water leaving the plant, and at three sample points
in the distribution system (near the first customer, an average
residence time, and a maximum residence time). Plants using hypochlorite
solutions were required to collect quarterly samples of the water
entering and leaving the plant. If chlorine dioxide or hypochlorite
solutions were used intermittently at a plant, chlorate ion samples were
only required in sample periods in which they were in use.

The ICR Database was considered the more appropriate data source for
estimating average chlorate concentrations in drinking water from
individual water treatment plants. The AwwaRF study is a less robust
data set, consisting of only one sample per utility, whereas the ICR
database included multiple samples over an 18 month period. Both the
AwwaRF study and the ICR data reveal high concentrations of chlorate ion
to be a local problem affecting a relatively small number of systems.

Based on the ICR monitoring data, the Agency was able to assess exposure
to chlorate in drinking water. The ICR data confirm the presence of
chlorate in untreated source water which may be the result of
agricultural and other uses of sodium chlorate. However, the chlorate
concentrations in ambient water are generally very low and are minor
compared to those observed in drinking water treated with chlorine
dioxide or hypochlorite. Table 4 below summarizes the annual chlorate
concentrations calculated for each plant. The data listed for
hypochlorite plants is the average chlorate concentrations, taken from
samples collected at the entry point to a distribution system. The
figures for chlorine dioxide in the next two columns (chlorine dioxide
plans and combined hypochlorite and chlorine dioxide plants) represent
the distribution system average chlorate concentrations. As previously
explained, for chlorine dioxide plants, samples were collected from
three points in the distribution systems; the data from these three
collection points were used to calculate a distribution system average.
Monitoring in the distribution system was required by the ICR, since
chlorate concentrations are expected to change as the water travels
through the distribution system. The concentration changes, because many
of the chlorine dioxide systems use chlorine to maintain a disinfectant
residual in the distribution system, and chlorine reacts with the
chlorite ion to form chlorate ion.

+-----------------------+-------------+-------------+-----------------+
| **Table 4.**          |             |             |                 |
| **Distribution of     |             |             |                 |
| Average Annual**      |             |             |                 |
| Number range          |             |             |                 |
| CHAPTER**Chlorate     |             |             |                 |
| Concentrations - ICR  |             |             |                 |
| Data**                |             |             |                 |
+-----------------------+-------------+-------------+-----------------+
|                       | **Hyp       | **Chlorine  | **Combined      |
|                       | ochlorite** | Dioxide**   | Hypochlorite    |
|                       |             |             | and Chlorine    |
|                       | **          | **Plants    | Dioxide         |
|                       | Plants^a^** | ^b^**       | Plants**        |
+-----------------------+-------------+-------------+-----------------+
| Number of Public      | 44          | 22          | 66              |
| Water Systems         |             |             |                 |
+-----------------------+-------------+-------------+-----------------+
| Number of Water       | 61          | 29          | 90              |
| Treatment Plants      |             |             |                 |
+-----------------------+-------------+-------------+-----------------+
| **Chlorate            |             |             |                 |
| Concentration**       |             |             |                 |
| **(μg/L)**            |             |             |                 |
+-----------------------+-------------+-------------+-----------------+
| 10th Percentile       | 23          | 52          | 24              |
+-----------------------+-------------+-------------+-----------------+
| 20th Percentile       | 37          | 79          | 53              |
+-----------------------+-------------+-------------+-----------------+
| 50th Percentile       | 99          | 129         | 108             |
| (Median)              |             |             |                 |
+-----------------------+-------------+-------------+-----------------+
| 80th Percentile       | 155         | 217         | 179             |
+-----------------------+-------------+-------------+-----------------+
| 90th Percentile       | 239         | 264         | 242             |
+-----------------------+-------------+-------------+-----------------+
| Maximum               | 502         | 691         | 691             |
+-----------------------+-------------+-------------+-----------------+

> a\. Concentrations for hypochlorite plants are an average of samples
> collected from distribution system entry points.
>
> b\. For chlorine dioxide pants, the distribution system average
> concentration was calculated for each WTP using the three distribution
> system sample points.

**b.** **Acute Dietary Risk (Drinking Water)**

No acute dietary endpoint was selected because effects attributable to a
single dose were not seen in the available data; therefore, an acute
dietary (drinking water only) risk assessment was not conducted.

**c. Number range CHAPTERChronic Dietary Risk (Drinking Water)**

The chronic dietary (water only) risk assessment for chlorate in
drinking water, using the highest annual average concentration estimated
at 0.69 mg/L, is below 100% of the cPAD, and therefore, is below the
Agency's level of concern for the general US population and all
population subgroups except infants (\<1 year of age). The highest
exposed subgroup, infants, was 159% of the cPAD, based on the highest
annual average concentration of chlorate in Table 4 (0.69 mg/L). Using
the 90^th^ percentile annual average concentration estimated at 0.24
mg/L, the chronic (non-cancer) dietary (water only) risk for infants was
55% of the cPAD. Also for infants, using the median annual average
concentration estimated at 0.11mg/L, the risk was 25% of the cPAD. See
Table 5 below for details.

+---------------------+-----------+-----------+-----------+-----------+
| **T Table 5. Sum    |           |           |           |           |
| Table 5. Summary of |           |           |           |           |
| Estimated Chronic   |           |           |           |           |
| Dietary (water      |           |           |           |           |
| only) Exposure and  |           |           |           |           |
| Risk for**          |           |           |           |           |
|                     |           |           |           |           |
| **Sodium Chlorate   |           |           |           |           |
| by Average Annual   |           |           |           |           |
| Concentration in    |           |           |           |           |
| Large Drinking      |           |           |           |           |
| Water Systems**     |           |           |           |           |
+=====================+===========+===========+===========+===========+
| **Population        | **cPAD**  | **%       |           |           |
| Subgroup**          |           | cPAD**    |           |           |
|                     | **mg      |           |           |           |
|                     | /kg/day** |           |           |           |
+---------------------+-----------+-----------+-----------+-----------+
|                     |           | **Water   | **Water   | **Water** |
|                     |           | Estimated | Estimated |           |
|                     |           | at the**  | at the**  | **        |
|                     |           |           |           | Estimated |
|                     |           | **Highest | **90^th^  | at the    |
|                     |           | Annual    | P         | Median    |
|                     |           | Average** | ercentile | Annual    |
|                     |           |           | Annual    | Average** |
|                     |           | **(0.69   | Average** |           |
|                     |           | mg/L)**   |           | **(0.11   |
|                     |           |           | **(0.24   | mg/L)**   |
|                     |           |           | mg/L)**   |           |
+---------------------+-----------+-----------+-----------+-----------+
| General U.S.        | 0.03      | 49        | 17        | 8         |
| Population          |           |           |           |           |
+---------------------+-----------+-----------+-----------+-----------+
| All Infants (\< 1   |           | 159       | 55        | 25        |
| yr)                 |           |           |           |           |
+---------------------+-----------+-----------+-----------+-----------+
| Children 1-2 yrs    |           | 72        | 25        | 12        |
+---------------------+-----------+-----------+-----------+-----------+
| Children 3-5 yrs    |           | 67        | 23        | 11        |
+---------------------+-----------+-----------+-----------+-----------+
| Children 6-12 yrs   |           | 47        | 16        | 7         |
+---------------------+-----------+-----------+-----------+-----------+
| Youth 13-19 yrs     |           | 35        | 12        | 6         |
+---------------------+-----------+-----------+-----------+-----------+
| Adults 20-49 yrs    |           | 45        | 16        | 7         |
+---------------------+-----------+-----------+-----------+-----------+
| Adults 50+ yrs      |           | 48        | 17        | 8         |
+---------------------+-----------+-----------+-----------+-----------+
| Females 13-49 yrs   |           | 45        | 16        | 7         |
+---------------------+-----------+-----------+-----------+-----------+

[]{#__RefHeading___Toc140567149 .anchor}**7. Residential Exposure and
Risk**

[Number range CHAPTER]{.mark}Residential exposure assessments consider
all potential non-occupational pesticide exposure, other than exposure
due to residues in foods or in drinking water. For sodium chlorate, the
Agency has evaluated potential exposure and risk to sodium chlorate for
homeowners who handle (mix, load, and apply) products containing sodium
chlorate. The Agency also evaluated potential post-application exposure
and risk to adults and children entering sodium chlorate-treated areas,
such as lawns, or patio areas. Since the episodic nature of residential
exposure for sodium chlorate is inconsistent with the mechanism of
chlorate carcinogenicity, a residential cancer risk assessment was not
conducted.

To estimate residential non-cancer (dermal and inhalation) risks, the
Agency calculates a margin of exposure (MOE), which is the ratio of the
NOAEL selected for risk assessment to the exposure. This MOE is compared
to a level of concern which is the same value as the uncertainty factor
(UF) applied to a particular toxicity study. The standard UF is 100x
(10x to account for interspecies extrapolation and 10x for intraspecies
variation), plus any additional FQPA SF retained due to concerns unique
to the protection of infants and children. The FQPA SF for sodium
chlorate is reduced to1x for reasons explained above; thus, the Agency's
LOC is 100.

**a. Residential Handler Risks**

The Agency determined that there is the potential for residential
handlers to be exposed to sodium chlorate in outdoor residential
settings during the application of conventional pesticide products
containing sodium chlorate as the active ingredient. Sodium chlorate can
be used as a non-selective herbicide in outdoor residential environments
as a spot treatment or edging treatment around patios, along fence
lines, lawn edges, around foundations, underneath or around wood decks,
and in cracks and crevices of driveways. Although there is the potential
for dermal exposure by residential handlers, sodium chlorate is an
inorganic salt; therefore, significant absorption of sodium chlorate
through intact skin is not expected. Hence, only a short-term risk
assessment for residential handlers exposed to sodium chlorate *via* the
inhalation exposure route was conducted.

The risk assessment considered seven residential exposure scenarios
based on the types of equipment and techniques that can potentially be
used to make sodium chlorate applications, such as handheld equipment
(hand wand sprayers) and ready-to-use (RTU) methods (sprinkler cans).
The use patterns assessed are representative of the range of sodium
chlorate residential uses.

The Agency considered residential handler exposure scenarios to be
short-term (1-30 days) only due to infrequency of use associated with
homeowner products. The residential risk assessment is also based on
estimates of what and how much homeowners would typically treat, such as
the size of the lawn or garden, based on the Agency's standard operating
procedures for residential exposures. For more information on the daily
volume handled and the area treated used in each residential handler
scenarios, refer to *Inorganic Chlorates: Residential and Occupational
Exposure Assessment for the Reregistration Eligibility Decision
Document*, dated January 26, 2006.

Risk to homeowners handling sodium chlorate products are below the
Agency's LOC. The inhalation MOEs for all scenarios assessed are greater
than 100 (ranging from 370 to 710,000). See Table 6 for further detail.

+------------------------+---------+--------------+--------+--------+
| **Table 6. Sodium      |         |              |        |        |
| Chlorate Residential   |         |              |        |        |
| Risk Estimates^1^**    |         |              |        |        |
+========================+=========+==============+========+========+
| **Exposure Scenario    | **Daily | **C          | *      | **Inha |
| (Scenario #)**         | Area    | rop/Target** | *Appli | lation |
|                        | Tr      |              | cation | MO     |
|                        | eated** |              | Rate** | E^2^** |
+------------------------+---------+--------------+--------+--------+
| M                      | 1000    | Spot/edging  | 23.7   | 3000   |
| ixing/loading/applying | ft      | treatment    |        |        |
| liquids with a low     | ^2^/day |              | lb     |        |
| pressure hand wand     |         |              | a      |        |
| sprayer                |         |              | i/1000 |        |
|                        |         |              | ft^2^  |        |
+------------------------+---------+--------------+--------+--------+
| Loading/applying RTU   | 1       | Spot/edging  | 0.196  | 87000  |
| liquid with a trigger  | gal     | treatment    |        |        |
| pump sprayer           | lon/day |              | lb     |        |
|                        |         |              | ai/    |        |
|                        |         |              | gallon |        |
+------------------------+---------+--------------+--------+--------+
| M                      | 1000    | Spot/edging  | 23.7   | 5200   |
| ixing/loading/applying | ft      | treatment    |        |        |
| liquids with a         | ^2^/day |              | lb     |        |
| sprinkler can          |         |              | a      |        |
|                        |         |              | i/1000 |        |
|                        |         |              | ft^2^  |        |
+------------------------+---------+--------------+--------+--------+
| Applying liquid with a | 1       | Spot/edging  | 0.27   | 710000 |
| RTU sprinkler can      | gallon  | treatment    |        |        |
|                        | /day    |              | lb     |        |
|                        |         |              | ai/    |        |
|                        |         |              | gallon |        |
+------------------------+---------+--------------+--------+--------+
| Applying granules by   | 1000    | Spot/edging  | 12     | 370    |
| hand                   | ft      | treatment    |        |        |
|                        | ^2^/day |              | lb     |        |
|                        |         |              | a      |        |
|                        |         |              | i/1000 |        |
|                        |         |              | ft^2^  |        |
+------------------------+---------+--------------+--------+--------+
| Loading and applying   | 1000    | Spot/edging  | 12     | 2800   |
| granules with a belly  | ft      | treatment    |        |        |
| grinder                | ^2^/day |              | lb     |        |
|                        |         |              | a      |        |
|                        |         |              | i/1000 |        |
|                        |         |              | ft^2^  |        |
+------------------------+---------+--------------+--------+--------+
| Loading and applying   | 1000    | Spot/edging  | 12     | 200000 |
| granules with a        | ft      | treatment    |        |        |
| push-type spreader     | ^2^/day |              | lb     |        |
|                        |         |              | a      |        |
|                        |         |              | i/1000 |        |
|                        |         |              | ft^2^  |        |
+------------------------+---------+--------------+--------+--------+

1\. Residential exposures assessments do not include personal protective
equipment (PPE).

2\. Inhalation MOE = Oral NOAEL (30 mg/kg/day) / Daily Inhalation Dose.
The LOC for MOE is 100.

**b. Residential Post-Application Risks**

The Agency uses the term "post-application" to describe exposures to
individuals that occur as a result of being in an environment that has
been previously treated with a pesticide. Unlike residential handler
exposure, where the EPA assumed only adults will be handling and
applying sodium chlorate products, individuals of varying ages can
potentially be exposed when reentering or performing activities in areas
that have been previously treated. For products containing sodium
chlorate as the active ingredient, a post-application exposure
assessment was not conducted for the following reasons:

-   Although potential for post-application dermal exposure in
    residential and occupational settings exists, sodium chlorate is an
    inorganic salt; therefore, significant absorption of sodium chlorate
    through the skin is not expected.

-   Post-application inhalation exposure is not expected due to a
    negligible vapor pressure.

-   Post-application exposure assessments for residential settings
    (dermal and incidental oral) are not typically performed for spot
    treatments/edging treatments.

However, for products containing sodium chlorate as an inert ingredient,
there is the potential for post-application exposure in outdoor
residential settings from entering areas previously treated. Therefore,
a residential post-application risk assessment was conducted based on
this use. As an inert ingredient in herbicide formulations
professionally broadcast on residential sites, there is potential for
children to have incidental oral exposures *(i.e.,* hand-to-mouth,
object-to-mouth, and soil ingestion). As stated above, residential
post-application exposures *via* dermal and inhalation routes are not of
concern. Although there is the potential for post-application dermal
exposure in residential settings, sodium chlorate is an inorganic salt;
therefore, significant dermal absorption of sodium chlorate through
intact skin is not expected. Post-application inhalation exposure for
sodium chlorate is not expected due to negligible vapor pressure.

A series of conservative assumptions and exposure factors served as the
basis for completing the residential post-application risk assessment,
and those assumptions and factors are listed in detail in the previously
referenced *Inorganic Chlorates: Residential and Occupational Exposure
Assessment for the Reregistration Eligibility Decision Document*, dated
January 26, 2006. The risk estimates for incidental oral exposures to
sodium chlorate as an inert ingredient in other pesticide formulations
and the highest exposed population subgroup are shown in Table 7. The
combined oral MOE of 23,000 is greater than 100; therefore, the risk is
below the Agency's level of concern.

  ------------------ --------------------------- ------- --------- ------------
  **Table 7.                                                       
  Residential                                                      
  Post-application                                                 
  Risk Estimates for                                               
  Sodium Chlorate as                                               
  an Inert                                                         
  Ingredient in                                                    
  Herbicide Products                                               
  Applied                                                          
  Professionally to                                                
  Residential                                                      
  Sites**                                                          

  Population         Scenario                    Route   MOE       Combined MOE
  Subgroup                                                         

  Child              Hand-to-Mouth               Oral    29000     23000

                     Object-to-Mouth             Oral    110000    

                     Soil Ingestion              Oral    8600000   
  ------------------ --------------------------- ------- --------- ------------

[]{#__RefHeading___Toc140567150 .anchor}**8. Number range
CHAPTERAggregate Risk**

The FQPA amendments to the Federal Food, Drug, and Cosmetic Act (FFDCA,
Section 408(b)(2)(A)(ii)) require "that there is a reasonable certainty
that no harm will result from aggregate exposure to the pesticide
chemical residue, including all anticipated dietary exposures and other
exposures for which there is reliable information." Aggregate exposure
will typically include exposures from food, drinking water, residential
uses of a pesticide, and other non-occupational sources of exposure.

In accordance with FQPA, the Agency must consider and aggregate
pesticide exposures and risks from three major sources: food, drinking
water, and if applicable, residential or other non-occupational
exposures. In an aggregate assessment, exposures from relevant sources
are added together and compared to quantitative estimates of hazard
(e.g., a NOAEL), or the risks themselves can be aggregated. When
aggregating exposures and risks from various sources, the Agency
considers both the route and duration of exposure. Aggregate exposure
and risk assessments for sodium chlorate include the following
scenarios: short-term (food + water + residential handler) and chronic
dietary (food + drinking water). Results of the aggregate risk
assessment are summarized here, and are discussed more extensively in
the document: *Revised Inorganic Chlorates. HED Chapter of the
Reregistration Eligibility Decision Document (RED)* dated January 26,
2006, which is available in the public docket and on the internet.

**a. Short-Term Aggregate Risk (food + drinking water)**

Short-term aggregate risk was assessed for adults only, using the
highest exposure scenario (inhalation exposure while applying granules
by hand). Short-term aggregate risk for children would be less than the
short-term aggregate risk for adults (MOE of 324), because the
short-term MOE for residential risk to children from the use of sodium
chlorate as an inert is significantly greater *(i.e.,* lower risk) than
the residential handler short-term MOE for adults. Thus, all short-term
aggregate risks are below the Agency's level of concern (*i.e.*, MOEs
are greater than 100), as presented in Table 8.

+---------+------------+---------+------------+----------------------+
| **Table |            |         |            |                      |
| 8.      |            |         |            |                      |
| Sho     |            |         |            |                      |
| rt-Term |            |         |            |                      |
| Ag      |            |         |            |                      |
| gregate |            |         |            |                      |
| Risk    |            |         |            |                      |
| Calcula |            |         |            |                      |
| tions** |            |         |            |                      |
+---------+------------+---------+------------+----------------------+
| **Popul | **Target   | **MOE** | **MOE      | **Aggregate MOE**    |
| ation** | Aggregate  |         | in         |                      |
|         | MOE**      | *       | halation** | **(food + water +    |
|         |            | *Food + |            | residential)**       |
|         |            | water** |            |                      |
+---------+------------+---------+------------+----------------------+
| Adult   | 100        | 1715    | 400        | 324                  |
+---------+------------+---------+------------+----------------------+

**b. Chronic Aggregate Risk (food + drinking water)**

Since no chronic residential (non-dietary) exposure scenarios have been
identified, the chronic aggregate risk assessment considers exposure
only through food and drinking water. To assess aggregate risks from
chronic food and drinking water exposure, the Agency used conservative
Tier 1 chronic food estimates and incorporated drinking water monitoring
data collected under the Information Collection Rule (ICR). For chronic
aggregate dietary risks, using the estimated highest annual average of
drinking water concentrations, food and drinking water chronic exposure
estimates were above the Agency's level of concern for all infants (\<1
year old), the most highly exposed population, at 174% cPAD. Chronic
aggregate dietary risks were at the Agency's level of concern (100 %
cPAD) for children 1-2 years of age. All other population subgroups were
\<100 % cPAD, and therefore, below the Agency's level of concern. At the
90^th^ percentile and median annual average water concentration, all
population subgroups are below the Agency's LOC. The results of this
assessment for sodium chlorate are presented below in Table 9.

+---------------------+-----------+------------+----------+-----------+
| **Table 9. Summary  |           |            |          |           |
| of Chronic Dietary  |           |            |          |           |
| Aggregate (food +   |           |            |          |           |
| drinking water)     |           |            |          |           |
| Risk for Sodium     |           |            |          |           |
| Chlorate**          |           |            |          |           |
+=====================+===========+============+==========+===========+
| **Population        | **cPAD**  | **% cPAD   |          |           |
| Subgroup^a^**       |           | (food +    |          |           |
|                     | **(mg/    | drinking   |          |           |
|                     | kg/day)** | water)**   |          |           |
+---------------------+-----------+------------+----------+-----------+
|                     |           | **Highest  | **90th   | **Median  |
|                     |           | Annual     | Pe       | Annual    |
|                     |           | Average**  | rcentile | Average** |
|                     |           |            | Annual   |           |
|                     |           | **(0.69    | A        | **(0.11   |
|                     |           | mg/L)**    | verage** | mg/L)**   |
|                     |           |            |          |           |
|                     |           |            | **(0.24  |           |
|                     |           |            | mg/L)**  |           |
+---------------------+-----------+------------+----------+-----------+
| General US          | 0.03      | 58         | 26       | 17        |
| Population          |           |            |          |           |
+---------------------+-----------+------------+----------+-----------+
| All Infants (\< 1   |           | 174        | 70       | 40        |
| yr)                 |           |            |          |           |
+---------------------+-----------+------------+----------+-----------+
| Children 1-2 yrs    |           | 100        | 53       | 39        |
+---------------------+-----------+------------+----------+-----------+
| Children 3-5 yrs    |           | 90         | 47       | 34        |
+---------------------+-----------+------------+----------+-----------+

[]{#__RefHeading___Toc140567151 .anchor}**9. Occupational Exposure and
Risk**

The occupational risk assessment addresses risks to workers who may be
exposed to sodium chlorate when mixing, loading, or applying a pesticide
(i.e., handlers), and when entering treated sites for routine tasks
(post-application). Please see Table 2 for the toxicological endpoints
used in the sodium chlorate occupational assessment. Based on the
registered use patterns of sodium-chlorate, short-term (1-30 days) and
intermediate-term (1-6 months) occupational exposures were assessed;
long-term (\> 6 months) exposure is not expected.

Exposure for workers generally occurs via the dermal or inhalation
route; however, since sodium chlorate is an inorganic salt, and
significant absorption of sodium chlorate through the skin is not
expected, a dermal toxicological endpoint was not selected. As such, a
risk assessment for dermal exposure was not performed. Similarly,
post-application exposure was not assessed due to the physical and
chemical characteristics of sodium chlorate as an inorganic salt; no
significant amount of sodium chlorate is expected to be absorbed through
the skin, and the vapor pressure is negligible. Further, for the
antimicrobial use of sodium chlorate in chlorine dioxide generation for
drinking water treatment, exposure to chlorate is expected to be
negligible because of its conversion to chlorine dioxide inside the
closed generators. Post-application exposure to chlorine dioxide will be
addressed in the chlorine dioxide risk assessment and RED.

The occupational assessment estimates non-cancer risks using the MOE
approach. MOEs greater than 100 are below the Agency's level of concern
for short- and intermediate-term occupational exposure.

Occupational exposure to sodium chlorate was assessed using data from
the Pesticide Handler Exposure Database (PHED) and Outdoor Residential
Exposure Task Force (ORETF). In addition, standard default assumptions
pertaining to average body weight, work day, and area treated daily were
used to calculate risk estimates. Application rates used in this
assessment are derived directly from current sodium chlorate labels.
Worker exposure and risk estimates are based on the best data currently
available to the Agency.

The occupational risk assessment is summarized here. For further detail,
see the following documents: (1) *Revised Inorganic Chlorates. HED
Chapter of the Reregistration Eligibility Decision Document (RED)* dated
January 26, 2006; (2) *Inorganic Chlorates: Occupational and Residential
Exposure Assessment for the Reregistration Eligibility Decision (RED)
Document (Case 4049)*, dated June 13, 2005; and (3) Sodium Chlorate:
Occupational and Residential Exposure Assessment of Antimicrobial Uses
for the Reregistration Eligibility Decision Document dated January 24,
2005.

**a. Handler Risks**

Occupational handler exposure assessments are conducted by the Agency
using different levels of protection. The Agency typically evaluates all
exposures with minimal protection and then adds protective measures in a
tiered approach to determine the level of protection necessary to obtain
appropriate MOEs. The lowest level (baseline) includes long sleeve
shirts, long pants, shoes, and socks. A single layer of PPE includes the
addition of chemical-resistant gloves to the baseline attire of long
sleeves, long pants, shoes, and socks. A respirator may also be added if
there is a concern for inhalation exposure. If MOEs at that level of PPE
are less than 100, increasing levels of PPE are applied (*i.e.,*
coveralls are added to provide a double layer of protective clothing or
respirators). If MOEs are still less than 100 with maximum PPE, then
engineering controls are applied (*i.e.,* enclosed cabs or cockpits and
closed mixing/loading systems). Note that the lower levels of PPE
protect against dermal exposure, and dermal exposure is not anticipated
for sodium chlorate. The types of protection, including PPE and
engineering controls, which were used to calculate inhalation
occupational exposure from sodium chlorate are as follows:

• Baseline: No respirator

• PPE: Dust/mist respirator with an 80% reduction factor

• Engineering Controls: Enclosed cockpits or enclosed cabs

Anticipated use patterns and current labeling for sodium chlorate
indicate several major occupational exposure scenarios that can result
in handlers receiving inhalation exposures to sodium chlorate, including
the antimicrobial use of sodium chlorate to generate chlorine dioxide
for drinking water treatment. These exposure scenarios are based on the
chemical formulations, equipment, and techniques that handlers can use
to make sodium chlorate applications. Exposures are also considered
based on their duration. The Agency assessed short- (1 to 30 days) and
intermediate-term (30 days to several months) exposures to sodium
chlorate, though the results were essentially the same because the
toxicological endpoints for short- and intermediate-term exposures are
the same in the case of sodium chlorate. For short and intermediate-term
exposures, MOEs greater than 100 are not of concern to the Agency.

Risks to handlers treating water systems are below the Agency's level of
concern, with inhalation MOEs of 800 to 95,000 depending on the size of
the generator. All sodium chlorate applications to chlorine dioxide
generators occur in closed delivery systems. In addition, risk for most
occupational handler scenarios do not exceed the Agency's level of
concern of 100 (i.e, most scenarios had MOEs \> 100) at the baseline
level of protection. However, risks for the following occupational
scenarios did exceed the Agency's level of concern at baseline level of
protection:

1.  Mixing/Loading liquids for groundboom application to
    industrial/non-crop sites at 1032 lb ai per acre (MOE = 42) and 523
    lb ai per acre (MOE = 84);

2.  Loading granules for tractor-drawn spreader applications to
    industrial/non-crop sites at 523 lb ai per acre (MOE = 59);

3.  Applying sprays to industrial/non-crop sites using groundboom
    equipment (open cab) at 1032 lb ai per acre (MOE = 69); at 523 lb ai
    per acre (MOE = 140);

4.  Mixing/Loading/Applying liquids for low pressure handwand
    applications to industrial/non-crop sites at 1032 lb ai per acre
    (MOE = 34) and 523 lb ai per acre (MOE = 67); and

5.  Loading/Applying granules to industrial/non-crop sites using a belly
    grinder at 523 lb ai per acre (MOE = 65);

Inhalation handler risk for these scenarios did not exceed the Agency's
level of concern with the addition of a dust/mist respirator (with an
80% reduction factor). Additionally, risks for certain scenarios were
below the Agency's level of concern, without the application of PPE or
engineering controls, once lower application rates were used. All risks
of concern were at the high end of application rates
([\>]{.underline}523 lb ai per acre), whereas at lower rates the risks
were not of concern. Table 10 summarizes the risk results for short-term
and intermediate-term occupational handlers.

+-----------+-------+----------------+--------+-------+----+--------+
| **Table   |       |                |        |       |    |        |
| 10.       |       |                |        |       |    |        |
| Sodium    |       |                |        |       |    |        |
| Chlorate: |       |                |        |       |    |        |
| Short-    |       |                |        |       |    |        |
| and       |       |                |        |       |    |        |
| Intermed  |       |                |        |       |    |        |
| iate-Term |       |                |        |       |    |        |
| Occ       |       |                |        |       |    |        |
| upational |       |                |        |       |    |        |
| I         |       |                |        |       |    |        |
| nhalation |       |                |        |       |    |        |
| E         |       |                |        |       |    |        |
| xposure** |       |                |        |       |    |        |
+===========+=======+================+========+=======+====+========+
| *         | **    | *              | *      | **    | ** | *      |
| *Exposure | Daily | *Crop/Target** | *Appli | Basel | PP | *Engin |
| S         | Area  |                | cation | ine** | E^ | eering |
| cenario** | Tr    |                | Rate** |       | 3^ | Cont   |
|           | eated |                |        | **    | ** | rols** |
|           | ^1^** |                | **(lb  | Inhal |    |        |
|           |       |                | a      | ation |    |        |
|           |       |                | i/A)** | MOE   |    |        |
|           |       |                |        | ^2^** |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
| **Mixer/  |       |                |        |       |    |        |
| Loaders** |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Mixin     | 1200  | Cotton, Corn,  | 7.5    | 190   | \  | \-\    |
| g/Loading |       | Rice, Dry      |        |       | -\ | -\-\-\ |
| liquids   |       | Beans, Grain   |        |       | -\ | -\-\-- |
| for       |       | Sorghum, Flax, |        |       | -\ |        |
| aerial    |       | Safflower,     |        |       | -\ |        |
| ap        |       | Sunflower,     |        |       | -\ |        |
| plication |       | Soybeans       |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Fallow Land,   | 6      | 240   | \  | \-\    |
|           |       | Wheat          |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 350   | Chili Peppers  | 12.5   | 400   | \  | \-\    |
|           |       | (for           |        |       | -\ | -\-\-\ |
|           |       | processing     |        |       | -\ | -\-\-- |
|           |       | only),         |        |       | -\ |        |
|           |       | Potatoes       |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Ornamental     | 6      | 830   | \  | \-\    |
|           |       | Gourds,        |        |       | -\ | -\-\-\ |
|           |       | Cucurbits      |        |       | -\ | -\-\-- |
|           |       | (grown for     |        |       | -\ |        |
|           |       | seed)          |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Guar Beans,    | 7.5    | 670   | \  | \-\    |
|           |       | Southern Peas  |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Mixin     | 200   | Cotton, Corn,  | 7.5    | 1200  | \  | \-\    |
| g/Loading |       | Rice, Dry      |        |       | -\ | -\-\-\ |
| liquids   |       | Beans, Grain   |        |       | -\ | -\-\-- |
| for       |       | Sorghum, Flax, |        |       | -\ |        |
| g         |       | Safflower,     |        |       | -\ |        |
| roundboom |       | Sunflower,     |        |       | -\ |        |
| ap        |       | Soybeans       |        |       | -- |        |
| plication |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Fallow Land,   | 6      | 1500  | \  | \-\    |
|           |       | Wheat          |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 80    | Chili Peppers  | 12.5   | 1800  | \  | \-\    |
|           |       | (for           |        |       | -\ | -\-\-\ |
|           |       | processing     |        |       | -\ | -\-\-- |
|           |       | only),         |        |       | -\ |        |
|           |       | Potatoes       |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Ornamental     | 6      | 3600  | \  | \-\    |
|           |       | Gourds,        |        |       | -\ | -\-\-\ |
|           |       | Cucurbits      |        |       | -\ | -\-\-- |
|           |       | (grown for     |        |       | -\ |        |
|           |       | seed)          |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Guar Beans,    | 7.5    | 2900  | \  | \-\    |
|           |       | Southern Peas  |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 40    | Indus          | 1032   | 42    | 2  | \-\    |
|           |       | trial/Non-Crop |        |       | 10 | -\-\-\ |
|           |       | Sites          |        |       |    | -\-\-- |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 84    | 4  | \-\    |
|           |       |                |        |       | 20 | -\-\-\ |
|           |       |                |        |       |    | -\-\-- |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 330   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Mixin     | 5     | Rights-of-Way  | 1032   | 340   | \  | \-\    |
| g/Loading |       | &              |        |       | -\ | -\-\-\ |
| liquids   |       | Indus          |        |       | -\ | -\-\-- |
| for       |       | trial/Non-Crop |        |       | -\ |        |
| righ      |       | Sites          |        |       | -\ |        |
| ts-of-way |       |                |        |       | -\ |        |
| sprayer   |       |                |        |       | -- |        |
| ap        |       |                |        |       |    |        |
| plication |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 670   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 2700  | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Loading   | 40    | Indus          | 523    | 59    | 3  | \-\    |
| granules  |       | trial/Non-Crop |        |       | 00 | -\-\-\ |
| for       |       | Sites          |        |       |    | -\-\-- |
| trac      |       |                |        |       |    |        |
| tor-drawn |       |                |        |       |    |        |
| spreader  |       |                |        |       |    |        |
| ap        |       |                |        |       |    |        |
| plication |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 240    | 130   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 161    | 190   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| **Appl    |       |                |        |       |    |        |
| icators** |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Aerial    | 1200  | Cotton, Corn,  | 7.50   | \-\-\ | \  | 3400   |
| spray     |       | Rice, Dry      |        | -\-\- | -\ |        |
| app       |       | Beans, Grain   |        | \-\-- | -\ |        |
| lications |       | Sorghum, Flax, |        |       | -\ |        |
|           |       | Safflower,     |        |       | -\ |        |
| (enclosed |       | Sunflower,     |        |       | -\ |        |
| cockpit)  |       | Soybeans       |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Fallow Land,   | 6      | \-\-\ | \  | 4300   |
|           |       | Wheat          |        | -\-\- | -\ |        |
|           |       |                |        | \-\-- | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 350   | Guar Beans,    | 7.5    | \-\-\ | \  | 12000  |
|           |       | Southern Peas  |        | -\-\- | -\ |        |
|           |       |                |        | \-\-- | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Chili Peppers  | 12.5   | \-\-\ | \  | 7100   |
|           |       | (for           |        | -\-\- | -\ |        |
|           |       | processing     |        | \-\-- | -\ |        |
|           |       | only),         |        |       | -\ |        |
|           |       | Potatoes       |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Ornamental     | 6      | \-\-\ | \  | 15000  |
|           |       | Gourds,        |        | -\-\- | -\ |        |
|           |       | Cucurbits      |        | \-\-- | -\ |        |
|           |       | (grown for     |        |       | -\ |        |
|           |       | seed)          |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| G         | 1200  | Cotton, Corn,  | 7.5    | 1900  | \  | \-\    |
| roundboom |       | Rice, Dry      |        |       | -\ | -\-\-\ |
| spray     |       | Beans, Grain   |        |       | -\ | -\-\-- |
| app       |       | Sorghum, Flax, |        |       | -\ |        |
| lications |       | Safflower,     |        |       | -\ |        |
|           |       | Sunflower,     |        |       | -\ |        |
|           |       | Soybeans       |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Fallow Land,   | 6      | 2400  | \  | \-\    |
|           |       | Wheat          |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 350   | Guar Beans,    | 7.5    | 4700  | \  | \-\    |
|           |       | Southern Peas  |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Chili Peppers  | 12.5   | 2800  | \  | \-\    |
|           |       | (for           |        |       | -\ | -\-\-\ |
|           |       | processing     |        |       | -\ | -\-\-- |
|           |       | only),         |        |       | -\ |        |
|           |       | Potatoes       |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       | Ornamental     | 6      | 5900  | \  | \-\    |
|           |       | Gourds,        |        |       | -\ | -\-\-\ |
|           |       | Cucurbits      |        |       | -\ | -\-\-- |
|           |       | (grown for     |        |       | -\ |        |
|           |       | seed)          |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           | 40    | Indus          | 1032   | 69    | 3  | 1200   |
|           |       | trial/Non-Crop |        |       | 40 | (      |
|           |       | Sites          |        |       |    | closed |
|           |       |                |        |       |    | cab)   |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 140   | \  | 2300   |
|           |       |                |        |       | -\ | (      |
|           |       |                |        |       | -\ | closed |
|           |       |                |        |       | -\ | cab)   |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 540   | \  | 9200   |
|           |       |                |        |       | -\ | (      |
|           |       |                |        |       | -\ | closed |
|           |       |                |        |       | -\ | cab)   |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Righ      | 5     | Rights-of-Way  | 1032   | 110   | \  | \-\    |
| ts-of-way |       | &              |        |       | -\ | -\-\-\ |
| sprayer   |       | Indus          |        |       | -\ | -\-\-- |
| app       |       | trial/Non-Crop |        |       | -\ |        |
| lications |       | Sites          |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 210   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 820   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Trac      | 40    | Indus          | 523    | 84    | 4  | 460    |
| tor-drawn |       | trial/Non-Crop |        |       | 20 | (      |
| spreader  |       | Sites          |        |       |    | closed |
| app       |       |                |        |       |    | cab)   |
| lications |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 240    | 180   | \  | 990    |
|           |       |                |        |       | -\ | (      |
|           |       |                |        |       | -\ | closed |
|           |       |                |        |       | -\ | cab)   |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 161    | 270   | \  | 1500   |
|           |       |                |        |       | -\ | (      |
|           |       |                |        |       | -\ | closed |
|           |       |                |        |       | -\ | cab)   |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| **F       |       |                |        |       |    |        |
| laggers** |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
| Flagging  | 350   | Various        | 12.5   | 1400  | \  | \-\    |
| for       |       | Agricultural   |        |       | -\ | -\-\-\ |
| aerial    |       | Crops          |        |       | -\ | -\-\-- |
| spray     |       |                |        |       | -\ |        |
| app       |       |                |        |       | -\ |        |
| lications |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| **Mixer/  |       |                |        |       |    |        |
| Loader/Ap |       |                |        |       |    |        |
| plicators |       |                |        |       |    |        |
| &         |       |                |        |       |    |        |
| Lo        |       |                |        |       |    |        |
| ader/Appl |       |                |        |       |    |        |
| icators** |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
| M/L/A     | 2     | Indus          | 1032   | 34    | 1  | \-\    |
| liquids   |       | trial/Non-Crop |        |       | 70 | -\-\-\ |
| with a    |       | Sites          |        |       |    | -\-\-- |
| low       |       |                |        |       |    |        |
| pressure  |       |                |        |       |    |        |
| handwand  |       |                |        |       |    |        |
| sprayer   |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 67    | 3  | \-\    |
|           |       |                |        |       | 30 | -\-\-\ |
|           |       |                |        |       |    | -\-\-- |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 270   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| M/L/A     | 5     | Indus          | 1032   | 230   | \  | \-\    |
| liquids   |       | trial/Non-Crop |        |       | -\ | -\-\-\ |
| with a    |       | Sites          |        |       | -\ | -\-\-- |
| handgun   |       |                |        |       | -\ |        |
| sprayer   |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 523    | 450   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 132    | 1800  | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| L/A       | 1     | Indus          | 523    | 65    | 3  | \-\    |
| granules  |       | trial/Non-Crop |        |       | 20 | -\-\-\ |
| with a    |       | Sites          |        |       |    | -\-\-- |
| belly     |       |                |        |       |    |        |
| grinder   |       |                |        |       |    |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 240    | 140   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 161    | 210   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
| L/A       | 5     | Indus          | 523    | 110   | \  | \-\    |
| granules  |       | trial/Non-Crop |        |       | -\ | -\-\-\ |
| with a    |       | Sites          |        |       | -\ | -\-\-- |
| push-type |       |                |        |       | -\ |        |
| spreader  |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 240    | 240   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+
|           |       |                | 161    | 360   | \  | \-\    |
|           |       |                |        |       | -\ | -\-\-\ |
|           |       |                |        |       | -\ | -\-\-- |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -\ |        |
|           |       |                |        |       | -- |        |
+-----------+-------+----------------+--------+-------+----+--------+

1\. Amount treated is presented in acres/day.

2\. Inhalation MOE = Oral NOAEL (30 mg/kg/day) / Daily Inhalation Dose.
LOC for MOE is 100.

3\. PPE dust/mist respirator with an 80% reduction factor.

a.  **Incident** **Reports**

Number range CHAPTER Number range CHAPTERAvailable sources of incident
data in humans were reviewed for the active ingredients sodium chlorate
and calcium chlorate (not currently registered). No data were found in
any of the available databases on calcium chlorate, so this review
exclusively addresses sodium chlorate. Data were available from the
following sources: OPP Incident Data System (IDS) consisting of reports
submitted to EPA by registrants, other federal and state health and
environmental agencies, and the public, since 1992; Poison Control
Centers (1993-2001); California Department of Pesticide Regulation for
pesticide poisoning since 1982; National Pesticide Telecommunications
Network (NPTN) for ranking of the top 200 active ingredients for which
phone calls were received during calendar years 1984-1991; and National
Institute of Occupational Safety and Health's Sentinel Event
Notification System for Occupational Risks (NIOSH SENSOR) from
1998-2002.

A total of 21 cases were recorded by the Poison Control Center from 1993
through 2001. Seven reported minor symptoms, and two reported moderate
medical outcomes, primarily due to dermal effects such as swelling and
rash. It is difficult to draw any conclusions from these reports because
of the small number of cases.

Detailed descriptions of 36 cases submitted to the California Pesticide
Illness Surveillance Program (1982-2002) were reviewed. However, sodium
chlorate was determined to be the primary cause of illness in just four
of these cases, and all four occurred in an agricultural setting (three
in cotton fields and one unknown). Two of these cases were classified as
systemic and one each involved skin or eye effects. The two systemic
cases involved applicators; one with nausea and the other with nausea,
headache, and itching skin after spraying for one week. Both of these
cases were classified as "possibly" due to sodium chlorate. The skin
case involved a worker exposed to drift from an adjacent field and the
eye case occurred when a worker bumped into a spray nozzle while getting
off the tractor and was splashed in the face. The skin case was
classified as "probably," and the eye case as "definitely," due to
sodium chlorate.

A number of suicidal ingestions of sodium chlorate have been reported in
the literature, and many of these have led to death. The chance of
ingesting a fatal dose accidentally is small unless the compound is
mistaken for a drug and taken purposely. However, a near-fatal poisoning
occurred when a 13-year-old boy "tasted" crystals of this weed killer
which he found in his father's shed. In spite of intensive treatment,
recovery did not begin until about the 15^th^ day and required a little
over 40 days.

Dermal absorption associated with agricultural use of sodium chlorate is
not sufficient to cause systemic poisoning. Even by mouth, a large dose
is required to produce illness. A 6.35% solution of potassium chlorate
was long used as a gargle, or a 300-mg tablet was allowed to dissolve
slowly in the mouth to treat pharyngitis before modern antibiotics
became available. The toxicities of the sodium and potassium salts are
similar. It was considered that a dose of 10,000 mg was fatal. The
smallest recorded fatal dose was 7500 mg. However, vigorous treatment
saved one person who had ingested about 40,000 mg.

[]{#__RefHeading___Toc140567152 .anchor}**B. Environmental Fate and
Effects Risk Assessment**

A summary of the Agency's environmental fate and effects risk assessment
is presented below. For detailed discussion of all aspects of the
environmental risk assessment, please see the *Revised Environmental
Fate and Ecological Risk Assessment of Sodium Chlorate,* dated June 1,
2006; it is available on the internet and in the public docket. This
risk assessment was refined and updated to incorporate public comments
and data received during the phase 3 public comment period.

[]{#__RefHeading___Toc140567153 .anchor}**1. Environmental Fate and
Transport**

Sodium chlorate, an inorganic salt, is not a naturally occurring
chemical. It is made by electrolysis of brine under controlled
temperature and pH conditions to optimize the efficiency of the process
and yield. Since targeted, guideline studies designed to understand the
environmental fate of chlorate are not available, open, peer-reviewed
chemical literature and descriptive chemistry of the chlorine system
were used as the basis for understanding the redox behavior of chlorate
(at least on a qualitative basis) and for generating a screening-level
environmental fate assessment.

Physical and chemical properties of a chemical can be used to identify
potential routes of exposure. For example, the vapor pressure and
Henry's Law Constant provide an indication of the potential to
volatilize from soil and water (partitioning into air), and the
n-octanol/water partition coefficient provides an indication of the
potential to bioaccumulate in fish or other aquatic organisms. Based on
the very low vapor pressure and very high solubility of sodium chlorate
in water, sodium chlorate is not expected to volatilize from soil or
water. In addition, the low log n-octanol/water partition coefficient
indicates that sodium chlorate has low potential to bioaccumulate.

As stated above, sodium chlorate is highly soluble. In addition, sodium
chlorate is completely ionized in water, thus producing sodium (Na^+^)
and the chlorate (ClO ~3~^-^) anion. Anions do not bind readily to soil
or sediment particulates[^1] and, therefore, are expected to be very
mobile. Assuming that chlorate does not undergo any redox reactions, it
is expected to be very mobile and to partition predominantly into the
water. However, extensive redox reactions are expected to occur in the
environment that will reduce the concentration of chlorate in the water
column.

The redox chemistry[^2] of chlorate affects its behavior in soils and
natural water. Therefore, identification of the conditions under which
chlorate and other oxyanions of chlorine may predominate is an important
consideration in the environmental fate and risk assessment of chlorate.
The oxidation-reduction reactions of chlorate with organic matter and
other inorganic chemical species are very complex and depend on the
redox conditions of the media, nature and concentration of reductants,
chlorate concentration, temperature, pH, and degree of moisture (soils).
For example, chlorate is generally more stable under alkaline than
acidic conditions; however, when a chemical element (chlorine) can exist
in two or more oxidation states (i.e., chlorite and chlorate), the redox
potential of the media also effects the predominance of the reduction
products. Nitrate concentrations in soil and water (as well as other
physical and chemical properties of soil and water) play an important
role in the redox chemistry of chlorate in the environment.

[]{#__RefHeading___Toc140567154 .anchor}**2. Ecological Exposure and
Risk**

Number range CHAPTERTo estimate potential ecological risk, EPA
integrates the results of exposure and ecotoxicity studies using the
risk quotient method. Risk quotients (RQs) are calculated by dividing
acute and chronic estimated environmental concentrations (EECs) by
ecotoxicity values for various wildlife and plant species. RQs are then
compared to levels of concern (LOCs), and when the RQ exceeds the level
of concern for a particular category, the Agency presumes a risk of
concern to that category. See Table 11 below for the Agency's ecological
LOCs. Risk characterization provides further information on potential
adverse effects and the possible impact of those effects by considering
the fate of the chemical and its degradates in the environment,
organisms potentially at risk, and the nature of the effects observed.

+-------------------------------------------------+-----+-------+-----+
| **Table 11. EPA's Ecological Levels of Concern  |     |       |     |
| (LOCs) and Risk Presumptions**                  |     |       |     |
+=================================================+=====+=======+=====+
| **If a calculated RQ is greater than the LOC    | *   | **    | *   |
| presented, then the Agency presumes that...**   | *LO | LOC** | *LO |
|                                                 | C** |       | C** |
|                                                 |     | **aq  |     |
|                                                 | *   | uatic | *   |
|                                                 | *te | anim  | *pl |
|                                                 | rre | als** | ant |
|                                                 | str |       | s** |
|                                                 | ial |       |     |
|                                                 | ani |       |     |
|                                                 | mal |       |     |
|                                                 | s** |       |     |
+-------------------------------------------------+-----+-------+-----+
| **Acute Risk ...**there is potential for acute  | 0.5 | 0.5   | 1.0 |
| risk; regulatory action may be warranted in     |     |       |     |
| addition to restricted use classification       |     |       |     |
+-------------------------------------------------+-----+-------+-----+
| **Acute Endangered Species ...**endangered      | 0.1 | 0.05  | 1.0 |
| species may be adversely affected               |     |       |     |
+-------------------------------------------------+-----+-------+-----+
| **Chronic Risk** ...there is potential for      | 1   | 1     | NA  |
| chronic risk                                    |     |       |     |
+-------------------------------------------------+-----+-------+-----+

**a. Terrestrial Organisms**

1.  **Birds and Mammals**

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a.  **Exposure**

Sodium chlorate may be applied as a spray (agricultural and
nonagricultural uses) or as granules (nonagricultural uses only). The
Agency's methods for assessing exposure to terrestrial organisms are
different for each of these application methods and are discussed below.

For spray applications, the Agency's terrestrial exposure model
(ELL-FATE) was used to estimate exposures and risks to avian and
mammalian species. Input values on avian and mammalian toxicity, as well
as chemical application and foliar dissipation half-life data, are
required to run the model. The model provides estimates of both exposure
concentrations and RQs. Specifically, the model provides estimates of
concentrations (maximum and average) of chemical residues on the surface
of different types of foliage that may be sources of exposure to avian,
mammalian, reptilian, or terrestrial phase amphibian receptors. The
surface residue concentration (ppm) is estimated by multiplying the
application rate (pounds active ingredient per acre) by a value specific
to each food item. In all screening-level assessments, the organisms are
assumed to consume 100% of their diet as one food type. These exposure
estimates are only applicable to the applied pesticide, sodium chlorate.
It is uncertain to what extent exposure to reduced species of chlorate,
such as chlorite, may occur.

ELL-FATE was run for sodium chlorate for use on agricultural crops using
the inputs provided in Table 12 below. In the absence of foliar
dissipation half-life data for sodium chlorate, the Agency's default
half-life value of 35 days was used for all scenarios.

  ---------------------------------------------------------------------------------
  **Table 12. Input Parameters                                      
  for Sodium Chlorate Used in                                       
  ELL-FATE**                                                        
  ------------------------------- ---------------- ---------------- ---------------
  **Crop**                        **Maximum        **No. of         **Application
                                  labeled          applications**   interval**
                                  application                       
                                  rate**                            

  Chili peppers; white/Irish      12.5 lbs ai/A    1                N/A
  potatoes                                                          

  Cotton                          7.5 lbs ai/A     2                30 days

  Corn; flax, guar; southern      7.5 lbs ai/A     1                N/A
  peas; rice; safflower; sorghum;                                   
  soybeans; sunflower                                               

  Agricultural fallow land; dried 6 lbs ai/A       1                N/A
  beans; corn; cucurbits, flax,                                     
  gourds; guar; southern peas;                                      
  white/Irish potatoes; rice;                                       
  safflower; sorghum; soybeans;                                     
  sunflower                                                         
  ---------------------------------------------------------------------------------

The predicted upper 90^th^ percentile and mean chlorate EECs
(agricultural and non-agricultural uses) on various wild animal food
items are presented in Table 13 below.

  ------------------------------------------------------------------------------------------------------------------------
  **Table 13. EECs (mg                                                                                         
  ai/kg-food item) for                                                                                         
  Terrestrial Animal                                                                                           
  Risk Assessment for                                                                                          
  Sodium Chlorate**                                                                                            
  -------------------- ------------- --------- ------------- ----------- ------------- --------- ------------- -----------
  **Crops**            **Predicted                                       **Predicted                           
                       90th                                              Mean Residue                          
                       Percentile                                        Levels**                              
                       Residue                                                                                 
                       Levels**                                                                                

                       **short       **tall    **broadleaf   **fruit,    **short       **tall    **broadleaf   **fruit,
                       grass**       grass**   forage, small pods,       grass**       grass**   forage, small pods,
                                               insects**     seeds,                              insects**     seeds,
                                                             small                                             small
                                                             insects**                                         insects**

  **Agricultural Uses                                                                                          
  (Spray                                                                                                       
  Applications)**                                                                                              

  Chili peppers;       3000          1400      1700          190         1100          450       560           88
  white/Irish potatoes                                                                                         

  Cotton               2800          1300      1600          170         990           420       520           81

  Corn; flax, guar;    1800          830       1000          110         640           270       340           53
  southern peas; rice;                                                                                         
  safflower; sorghum;                                                                                          
  soybeans; sunflower                                                                                          

  Agricultural fallow  1400          660       810           90          510           220       270           42
  land; dried beans;                                                                                           
  corn; cucurbits,                                                                                             
  flax, gourds; guar;                                                                                          
  southern peas;                                                                                               
  white/Irish                                                                                                  
  potatoes; rice;                                                                                              
  safflower; sorghum;                                                                                          
  soybeans; sunflower                                                                                          

  **Non-Agricultural                                                                                           
  Uses (Spray                                                                                                  
  Applications)**                                                                                              

  Industrial sites     12500         5700      7000          780         4400          1900      2300          360
  such as driveways,                                                                                           
  paths, brick walks,                                                                                          
  cobble gutters,                                                                                              
  tennis courts                                                                                                

  Parking lots, fence  125,000       57,000    70,000        7800        44,000        19,000    23,000        3600
  lines, building                                                                                              
  perimeters, ditch                                                                                            
  banks, picnic areas,                                                                                         
  vacant lots, wood                                                                                            
  decks, bleachers,                                                                                            
  cemeteries, fuel                                                                                             
  tanks, runways, helo                                                                                         
  pads, etc.                                                                                                   
  ------------------------------------------------------------------------------------------------------------------------

For granular applications, estimation of chlorate loading per unit area
(mg/ft^2^) is calculated. This approach, which is intended to represent
exposure via multiple routes (e.g., incidental ingestion of contaminated
soil, dermal contact with treated seed surfaces and soil during
activities in the treated areas, preening activities, and ingestion of
drinking water contaminated with pesticide) and not just direct
ingestion, considers observed effects in toxicity studies and relates
them to the amount of pesticide applied to surface area. The maximum
labeled application rate for the active ingredient is the basis for the
exposure estimate. The terrestrial EECs for sodium chlorate's
non-agricultural use granular applications are presented in Table 14
below.

+-------------------------------------------+-------------+------------+
| **Table 14. Range of Terrestrial EECs     |             |            |
| (Granular Applications) for Sodium        |             |            |
| Chlorate**                                |             |            |
|                                           |             |            |
| **Non-Agricultural Uses**                 |             |            |
+===========================================+=============+============+
| **Use**                                   | **          | **EEC      |
|                                           | Application | (mg/f      |
|                                           | Rate**      | t^2^)^a^** |
|                                           |             |            |
|                                           | **(lbs      |            |
|                                           | ai/A)**     |            |
+-------------------------------------------+-------------+------------+
| Parking lots, under asphalt paving, fence | 520         | 5400       |
| lines, building perimeters, ditch banks,  |             |            |
| picnic areas, vacant lots, wood decks,    |             |            |
| bleachers, cemeteries, fuel tanks,        |             |            |
| runways, helo pads, etc.                  |             |            |
+-------------------------------------------+-------------+------------+
| Around buildings, storage areas, fences,  | 160         | 1700       |
| pumps, machinery, fuel tanks,             |             |            |
| recreational areas, roadways, guard       |             |            |
| rails, airports, rights of ways.          |             |            |
+-------------------------------------------+-------------+------------+

a\. EEC = Application rate (lbs/Acre) x 453,000 mg/lb ÷ 43,600 sq
ft/Acre

**b. Toxicity**

Effects characterization describes the potential effects a pesticide can
produce in a terrestrial organism, and is based on registrant-submitted
studies that describe acute and chronic toxicity effects for various
terrestrial animals. Table 15 summarizes the toxicity effects and
reference values used to assess risks for sodium chlorate to mammals and
birds.

  -----------------------------------------------------------------------------
  **Table 15.                                    
  Toxicity                                       
  Reference                                      
  Values for                                     
  Mammals and                                    
  Birds for                                      
  Sodium                                         
  Chlorate.**                                    
  ------------- ------------- ------------------ ------------------------------
  **Exposure    **Species**   **Toxicity Value   **Effect**
  Scenario**                  Used in Risk       
                              Assessment**       

  **Mammals**                                    

  Acute         Rat           LD~50~ = \> 5000   At 5000 mg/kg-bw, 1/10 animals
                              mg/kg-bw           died.

  Chronic       Rat           NOAEC = 500        No reproductive effects
                              mg/kg-bw, highest  
                              dose tested        
                              (approx. 10,000    
                              ppm)               

  **Birds**                                      

  Acute         Mallard duck  LD~50~ \> 2510     No mortality and no clinical
                              mg/kg-bw           signs of toxicity were
                                                 observed.

  Chronic       Bobwhite      NOAEC = 271 ppm    The LOAEC was 964 ppm based on
                quail                            effects on egg production and
                                                 thickness, embryonic survival,
                                                 and hatchling body weight.
  -----------------------------------------------------------------------------

**c**. **Avian** **Risk Estimates**

Acute RQs for birds were not calculated, because no mortality or signs
of toxicity were observed in the submitted subacute or acute toxicity
studies at concentrations that are above the limit for these types of
studies.

Avian chronic RQs for agricultural crops, at the estimated upper 90^th^
percentile residue levels, are presented in Table 16 below. RQ values
for all crops and all avian food items assessed, except the fruits,
pods, seeds, and small insects category, marginally exceeded the
Agency's chronic LOC of 1.0. The highest chronic avian RQ was 11 (chili
pepper/potato and short grass scenario). Chronic RQs based on mean EECs,
although not presented here, would be approximately three times lower
for most food items than those based on the 90^th^ percentile residue
levels shown below.

  --------------------------------------------------------------------------
  **Table 16. Avian                                             
  Chronic Risk Quotients                                        
  for Sodium Chlorate                                           
  Agricultural Uses**                                           
  ------------------------ ------------ --------- ------------- ------------
  **Crops**                **Short      **Tall    **Broadleaf   **Fruit,
                           grass**      grass**   forage, small pods, seeds,
                                                  insects**     small
                                                                insects**

  Chili peppers;           11.0         5.2       6.3           0.7
  white/Irish potatoes                                          

  Cotton                   10.0         4.8       5.9           0.63

  Corn; flax, guar;        6.6          3.1       3.7           0.41
  southern peas; rice;                                          
  safflower; sorghum;                                           
  soybeans; sunflower                                           

  Agricultural fallow      5.2          2.4       3.0           0.33
  land; dried beans; corn;                                      
  cucurbits, flax, gourds;                                      
  guar; southern peas;                                          
  white/Irish potatoes;                                         
  rice; safflower;                                              
  sorghum; soybeans;                                            
  sunflower                                                     
  --------------------------------------------------------------------------

Chronic RQs for birds are not presented for chlorate's non-agricultural
uses (granular or spray). However, RQs would be considerably higher for
birds foraging where chlorate is applied at the rates assessed for the
non-agricultural uses. EECs ranged from 12,500 to 125,000 (short grass
food item), which would result in chronic avian RQs of 46 to 460. The
size of the treated areas for these uses is uncertain, and this will be
discussed further in Section IV of this document; therefore, the
likelihood that a bird would consume 100% of its diet from a
non-agricultural area treated with sodium chlorate is uncertain.

**d. Mammalian Risk Estimates**

Acute RQs were not calculated for mammals. The LD~50~ from a core acute
oral toxicity study in rats was \>5000 mg/kg-bw. In this study, 10%
(1/10) of the rats administered 5000 mg/kg died. Mortality was not
observed at any other dose. Therefore, the data were not sufficient to
allow for characterization of the dose-response relationship and the
proximity of the LD~50~ to 5000 mg/kg-bw is uncertain. For this reason,
acute RQs were not calculated. However, Tables 17 and 18 below present a
comparison of the body weight adjusted LD~50~s to the agricultural and
non-agricultural EECs, respectively, based on current use rates and the
spray application method. These ratios can be used to estimate high-end
acute risk to exposed mammals. Actual RQs would be lower than the values
in Tables 17 and 18.

+-------------+-------------+-------------+-------------+-------------+
| **Table 17. |             |             |             |             |
| Proximity   |             |             |             |             |
| of the      |             |             |             |             |
| lowest      |             |             |             |             |
| observed    |             |             |             |             |
| acute toxic |             |             |             |             |
| dose in     |             |             |             |             |
| mammals to  |             |             |             |             |
| the upper   |             |             |             |             |
| 90^th^      |             |             |             |             |
| percentile  |             |             |             |             |
| EEC         |             |             |             |             |
| (mg/kg-bw)  |             |             |             |             |
| for the     |             |             |             |             |
| range of    |             |             |             |             |
| maximum     |             |             |             |             |
| application |             |             |             |             |
| rates for   |             |             |             |             |
| all         |             |             |             |             |
| a           |             |             |             |             |
| gricultural |             |             |             |             |
| uses**      |             |             |             |             |
+=============+=============+=============+=============+=============+
| **Food      | **Size of   | **Adjusted  | **Range of  | **Ratio of  |
| item**      | mammal**    | lowest      | EECs**      | lowest      |
|             |             | observed    |             | observed    |
|             | **(grams)** | toxic dose  | **(mg/      | toxic dose  |
|             |             | (           | kg-bw)^a^** | to the      |
|             |             | mg/kg-bw)** |             | upper 90th  |
|             |             |             |             | percentile  |
|             |             |             |             | EEC         |
|             |             |             |             | (           |
|             |             |             |             | unitless)** |
+-------------+-------------+-------------+-------------+-------------+
| **Short     | 15          | 10,989      | 1400 - 2900 | 0.13 - 0.26 |
| grass**     |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
|             | 35          | 8891        | 950 - 2000  | 0.11 - 0.22 |
+-------------+-------------+-------------+-------------+-------------+
|             | 1000        | 3846        | 200 - 450   | 0.052 -     |
|             |             |             |             | 0.12        |
+-------------+-------------+-------------+-------------+-------------+
| **Tall      | 15          | 10,989      | 630 - 1300  | 0.057 -     |
| grass**     |             |             |             | 0.12        |
+-------------+-------------+-------------+-------------+-------------+
|             | 35          | 8891        | 440 - 910   | 0.049 -     |
|             |             |             |             | 0.10        |
+-------------+-------------+-------------+-------------+-------------+
|             | 1000        | 3846        | 99 - 210    | 0.026 -     |
|             |             |             |             | 0.055       |
+-------------+-------------+-------------+-------------+-------------+
| **Broadleaf | 15          | 10,989      | 770 - 1600  | 0.070 -     |
| p           |             |             |             | 0.15        |
| lants/small |             |             |             |             |
| insects**   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
|             | 35          | 8891        | 540 - 1100  | 0.061 -     |
|             |             |             |             | 0.12        |
+-------------+-------------+-------------+-------------+-------------+
|             | 1000        | 3846        | 120 - 250   | 0.031 -     |
|             |             |             |             | 0.065       |
+-------------+-------------+-------------+-------------+-------------+
| **Fruits,   | 15          | 10989       | 86 - 180    | \<0.01 -    |
| pods, large |             |             |             | 0.016       |
| insects**   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
|             | 35          | 8891        | 59 - 120    | \<0.01 -    |
|             |             |             |             | 0.013       |
+-------------+-------------+-------------+-------------+-------------+
|             | 1000        | 3846        | 14 - 28     | \<0.01 -    |
|             |             |             |             | \<0.01      |
+-------------+-------------+-------------+-------------+-------------+

a\. EECs were calculated by assuming that small, medium, and large
mammals consume 95%, 66%, and 15% of their body weight daily. Only the
highest and lowest EECs from chlorate's agricultural uses are used in
this assessment.

For sodium chlorate's agricultural uses, all of the acute ratios are
below the Agency's acute and endangered species LOC of 1.0 and 0.1,
respectively, with the exception of small mammals eating short grass.
The highest exceedence is for 15 gram mammals eating short grass (ratio
= 0.26).

Based on current non-agricultural use application rates, the only group
that does not exceed the Agency's acute mammalian LOC of 1.0 is animals
eating fruits, pods, or large insects (ratios range from 0.3 to 0.7).
The Agency's acute mammalian endangered species LOC of 0.1 is
potentially exceeded for all size animals and food items. While the
ratios presented in Table 18 suggest that there could be risk to mammals
of all sizes that forage in the area where chlorate is used for the
non-agricultural spray applications, the risk was likely over-estimated,
since an LD~50~ has not been established. The highest dose tested in the
available toxicity studies (5000 mg/kg-bw) induced 10% mortality. The
proximity of the LD~50~ to 5000 mg/kg-bw is uncertain. Furthermore, many
of the non-agricultural uses will likely result in small contiguously
treated areas; therefore, the likelihood that an animal will consume
100% of its diet from the areas treated with sodium chlorate is low for
some of these uses. Nonetheless, the EECs were predicted to be up to 11
times higher than 5000 mg/kg-bw for the non-agricultural uses.
Therefore, there may be some acute risk to mammals at levels of concern
to the Agency for non-agricultural uses.

+----------+--------+-----------------+-----------+-------------------+
| **Table  |        |                 |           |                   |
| 18.      |        |                 |           |                   |
| P        |        |                 |           |                   |
| roximity |        |                 |           |                   |
| of the   |        |                 |           |                   |
| lowest   |        |                 |           |                   |
| observed |        |                 |           |                   |
| acute    |        |                 |           |                   |
| toxic    |        |                 |           |                   |
| dose in  |        |                 |           |                   |
| mammals  |        |                 |           |                   |
| to the   |        |                 |           |                   |
| p        |        |                 |           |                   |
| redicted |        |                 |           |                   |
| EEC      |        |                 |           |                   |
| (m       |        |                 |           |                   |
| g/kg-bw) |        |                 |           |                   |
| for the  |        |                 |           |                   |
| range of |        |                 |           |                   |
| maximum  |        |                 |           |                   |
| app      |        |                 |           |                   |
| lication |        |                 |           |                   |
| rates    |        |                 |           |                   |
| for all  |        |                 |           |                   |
| non-agri |        |                 |           |                   |
| cultural |        |                 |           |                   |
| uses     |        |                 |           |                   |
| (spray   |        |                 |           |                   |
| applica  |        |                 |           |                   |
| tions)** |        |                 |           |                   |
+==========+========+=================+===========+===================+
| **Food   | **Size | **Adjusted      | **Range   | **Ratio of lowest |
| item**   | of     | lowest observed | of EECs** | observed toxic    |
|          | ma     | toxic dose**    |           | dose to the upper |
|          | mmal** |                 | **(mg/kg  | 90th percentile   |
|          |        | **(mg/kg-bw)**  | -bw)^a^** | EEC (unitless)**  |
|          | **(gr  |                 |           |                   |
|          | ams)** |                 |           |                   |
+----------+--------+-----------------+-----------+-------------------+
| **Short  | 15     | 10989           | 11,900 -  | 1.1 - 11          |
| grass**  |        |                 | 119,000   |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 35     | 8891            | 8200      | 0.93 - 9.3        |
|          |        |                 | **-**     |                   |
|          |        |                 | 82,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 1000   | 3846            | 1900 -    | 0.49 - 4.9        |
|          |        |                 | 19,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
| **Tall   | 15     | 10989           | 5400 -    | 0.49 - 4.9        |
| grass**  |        |                 | 54,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 35     | 8891            | 3800 -    | 0.43 - 4.3        |
|          |        |                 | 38,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 1000   | 3846            | 860 -     | 0.22 - 2.2        |
|          |        |                 | 8600      |                   |
+----------+--------+-----------------+-----------+-------------------+
| **B      | 15     | 10989           | 6700 -    | 0.61 - 6.1        |
| roadleaf |        |                 | 67,000    |                   |
| plan     |        |                 |           |                   |
| ts/small |        |                 |           |                   |
| i        |        |                 |           |                   |
| nsects** |        |                 |           |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 35     | 8891            | 4600 -    | 0.52 - 5.2        |
|          |        |                 | 46,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 1000   | 3846            | 1100 -    | 0.27 - 2.7        |
|          |        |                 | 11,000    |                   |
+----------+--------+-----------------+-----------+-------------------+
| *        | 15     | 10989           | 740 -     | 0.07 - 0.7        |
| *Fruits, |        |                 | 7400      |                   |
| pods,    |        |                 |           |                   |
| large    |        |                 |           |                   |
| i        |        |                 |           |                   |
| nsects** |        |                 |           |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 35     | 8891            | 520 -     | 0.06 - 0.6        |
|          |        |                 | 5200      |                   |
+----------+--------+-----------------+-----------+-------------------+
|          | 1000   | 3846            | 120 -     | 0.03 - 0.3        |
|          |        |                 | 1200      |                   |
+----------+--------+-----------------+-----------+-------------------+

a\. EECs were calculated by assuming that small, medium, and large
mammals consume 95%, 66%, and 15%, respectively, of their body weight
daily, and were calculated using the lowest and highest labeled
application rates (52 lbs ai/A and 520 lbs ai/A) that are most likely to
result in exposure

RQs were not calculated for acute risk for non-agricultural granular
applications for reasons previously discussed. However, Table 19 below
presents a comparison of the body weight adjusted lowest observed toxic
dose in rats (5000 mg/kg-day) to the granular application EECs
(mg/ft^2^). These ratios indicate a potential acute risk to mammals of
all size classes, as the lowest ratio (0.43 for large mammals and the
building and storage area perimeter scenario) exceeds the acute
endangered species LOC of 0.1.

[]{.mark}

+--------------------------+----------+----------+----------+----------+
| **Table 19. Range of     |          |          |          |          |
| ratios of chlorate's     |          |          |          |          |
| body weight adjusted     |          |          |          |          |
| LD~50~ to granular EECs  |          |          |          |          |
| (mg/ft^2^) for sodium    |          |          |          |          |
| chlorate's               |          |          |          |          |
| non-agricultural uses    |          |          |          |          |
| (granular                |          |          |          |          |
| formulations)**          |          |          |          |          |
+==========================+==========+==========+==========+==========+
| **Use**                  | **Body   | **Rat    | **EEC    | **Ratio  |
|                          | Weight   | LD~50~** | (mg/ft^  | of       |
|                          | (g)**    |          | 2^)^a^** | LD~50~   |
|                          |          | **mg     |          | to EEC** |
|                          |          | /kg-bw** |          |          |
+--------------------------+----------+----------+----------+----------+
| Parking lots, under      | 15       | 10,989   | 5400     | 33       |
| asphalt paving, fence    |          |          |          |          |
| lines, building          |          |          |          |          |
| perimeters, ditch banks, |          |          |          |          |
| picnic areas, vacant     |          |          |          |          |
| lots, wood decks,        |          |          |          |          |
| bleachers, cemeteries,   |          |          |          |          |
| fuel tanks, runways,     |          |          |          |          |
| helo pads, etc.          |          |          |          |          |
+--------------------------+----------+----------+----------+----------+
|                          | 35       | 8891     | 5400     | 17       |
+--------------------------+----------+----------+----------+----------+
|                          | 1000     | 3846     | 5400     | 1.4      |
+--------------------------+----------+----------+----------+----------+
| Around buildings,        | 15       | 10,989   | 1700     | 10       |
| storage areas, fences,   |          |          |          |          |
| pumps, machinery, fuel   |          |          |          |          |
| tanks, recreational      |          |          |          |          |
| areas, roadways, guard   |          |          |          |          |
| rails, airports, rights  |          |          |          |          |
| of ways.                 |          |          |          |          |
+--------------------------+----------+----------+----------+----------+
|                          | 35       | 8891     | 1700     | 5.4      |
+--------------------------+----------+----------+----------+----------+
|                          | 1000     | 3846     | 1700     | 0.43     |
+--------------------------+----------+----------+----------+----------+

a\. EEC = Application rate (lbs/Acre) x 453,000 mg/lb ÷ 43,600 sq
ft/Acre

For mammals, the Agency typically evaluates the mammalian reproductive
effects for exposures greater than 30 days. Interpretation of the RQs
resulting from the NOAEL of 500 mg/kg-day observed in a 2-generation rat
study is difficult in this respect. Although the study did indicate some
chronic effects, reproduction effects were not observed at any dose
level tested. Because 500 mg/kg was the highest dose tested, it is
uncertain whether there is a NOAEL for reproductive effects. In
addition, if there is an actual NOAEL for reproductive effects, it could
be much greater than 500 mg/kg.

However, the Agency calculated RQs based on the 500 mg/kg-day NOAEL as a
conservative estimate of risk, as presented in Table 20. Based on this
conservative estimate, chronic mammalian LOC of 1.0 was only slightly
exceeded for the smallest weight classes of mammals for most food items
and the largest weight class of mammals feeding on short grass. Based on
the lack of observed reproductive effects in the chronic study and the
slight RQs exceedances for agricultural uses, the Agency does not
anticipate a chronic risk of concern to mammals from agricultural uses
of sodium chlorate.

+-------------------+-----------+-----------+-----------+------------+
| **Table 20.       |           |           |           |            |
| Mammalian Chronic |           |           |           |            |
| Risk Quotients    |           |           |           |            |
| for Sodium        |           |           |           |            |
| Chlorate's        |           |           |           |            |
| Agricultural Uses |           |           |           |            |
| (Spay             |           |           |           |            |
| Application)**    |           |           |           |            |
+===================+===========+===========+===========+============+
| **Use**           | **Food    | **15-gram | **35-gram | *          |
|                   | Item**    | mammal**  | mammal**  | *1000-gram |
|                   |           |           |           | mammal**   |
+-------------------+-----------+-----------+-----------+------------+
| **Single          |           |           |           |            |
| application of    |           |           |           |            |
| 12.5 lbs ai/A**   |           |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
| **Chili peppers;  | Short     | 2.6       | 2.2       | 1.2        |
| white/Irish       | Grass     |           |           |            |
| potatoes**        |           |           |           |            |
|                   |           |           |           |            |
| **Chili peppers;  |           |           |           |            |
| white/Irish       |           |           |           |            |
| potatoes**        |           |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Tall      | 1.2       | 1.0       | 0.55       |
|                   | Grass     |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Broadleaf | 1.5       | 1.3       | 0.67       |
|                   | pla       |           |           |            |
|                   | nts/small |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Fruits/p  | 0.16      | 0.14      | 0.07       |
|                   | ods/large |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
| **Multiple        |           |           |           |            |
| applications (7.5 |           |           |           |            |
| lbs ai/A, 2       |           |           |           |            |
| applications,     |           |           |           |            |
| 30-day            |           |           |           |            |
| interval)**       |           |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
| **Cotton**        | Short     | 2.4       | 2.1       | 1.1        |
|                   | Grass     |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Tall      | 1.1       | 0.95      | 0.51       |
|                   | Grass     |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Broadleaf | 1.4       | 1.2       | 0.62       |
|                   | pla       |           |           |            |
|                   | nts/small |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Fruits/p  | 0.15      | 0.13      | 0.07       |
|                   | ods/large |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
| **Single          |           |           |           |            |
| application (7.5  |           |           |           |            |
| lbs ai/A)^a^**    |           |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
| **Corn**; flax,   | Short     | 1.6       | 1.3       | 0.72       |
| guar; southern    | Grass     |           |           |            |
| peas; rice;       |           |           |           |            |
| safflower;        |           |           |           |            |
| sorghum;          |           |           |           |            |
| soybeans;         |           |           |           |            |
| sunflower         |           |           |           |            |
|                   |           |           |           |            |
| **Agricultural    |           |           |           |            |
| fallow land;**    |           |           |           |            |
| dried beans;      |           |           |           |            |
| corn; cucurbitsa, |           |           |           |            |
| flax, gourds;     |           |           |           |            |
| guar; southern    |           |           |           |            |
| peas; white/Irish |           |           |           |            |
| potatoes; rice;   |           |           |           |            |
| safflower;        |           |           |           |            |
| sorghum;          |           |           |           |            |
| soybeans;         |           |           |           |            |
| sunflower         |           |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Tall      | 0.72      | 0.61      | 0.33       |
|                   | Grass     |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Broadleaf | 0.88      | 0.75      | 0.40       |
|                   | pla       |           |           |            |
|                   | nts/small |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+
|                   | Fruits/p  | 0.10      | 0.08      | 0.04       |
|                   | ods/large |           |           |            |
|                   | insects   |           |           |            |
+-------------------+-----------+-----------+-----------+------------+

a\. EECs and RQs are similar for the 7.5lbs a.i/A (corn, et al.) and 6.0
lbs a.i./A (agricultural fallow land, et al.) and single applications,
and LOC exceedances are equivalent; therefore, only results from the
single application of 7.5 lbs ai/A are presented.

Reproduction RQs were not calculated for chlorate's non-agricultural
uses (spray or granular applications). However, based on the high
application rates and resulting high potential EECs, risks from
chlorate's non-agricultural uses could be considerably higher than risks
presented for agricultural uses.

**2. Non-Target Insects**

EPA currently does not estimate RQs for terrestrial non-target insects.
Furthermore, the Agency has no insect toxicity data for sodium chlorate.

#####  **3. Non-Target Terrestrial Plants**

Based on chlorate's non-selective mode of action and lack of adequate
toxicity data, the Agency presumes risk to non-target terrestrial plants
at levels above the Agency's level of concern for all uses. The risks to
plants cannot be quantified at this time due to lack of data; however,
the Agency will require data to address this uncertainty.

**b. Aquatic Organisms**

At the present time, there is no methodology to estimate exposure
concentrations in water for non-metal inorganic chemical species that
can be found in different oxidation states (e.g., for inorganic chemical
species that can exhibit extensive pH-pE dependent redox chemistry, such
as the chlorine system). As an approximation on the impact of chlorate
on surface water quality, the Tier I GENEEC-2 simulation model was used
to estimate exposure concentrations in aquatic systems. Extreme
assumptions in the environmental persistence of chlorate were made that
resulted in high-end exposure concentrations in the standard ecological
pond scenario. The predicted chlorate concentrations are believed to be
high because the chemical speciation of chlorate was not considered in
the assessment. As previously discussed, under thermodynamic equilibrium
conditions, chloride is likely the predominant species in natural
environments. This analysis, however, indicates that chlorate can be
reduced to chloride, but not how fast the reduction will occur. Since
there are no input parameters for the model that take into account the
redox behavior of chlorate, it was assumed that unchanged chlorate runs
off into surface water, where it remains as chlorate.

Unlike the drinking water assessment described in the human health risk
assessment section of this document, the exposure values used in the
ecological risk assessment do not include the Index Reservoir (IR) and
Percent Cropped Area (PCA) factor refinements. These factors represent a
drinking water reservoir, not the variety of aquatic habitats relevant
to a risk assessment for aquatic animals, such as ponds adjacent to
treated fields. Therefore, the EEC values used to assess exposure and
risk to aquatic animals are not the same as those used to assess
exposure and risk to humans from pesticides in drinking water.

**1. Fish**

Acute toxicity studies for both freshwater and marine/estuarine fish
were consistent with a "practically non-toxic" designation for fish. No
effects were observed in sheepshead minnows (estuarine/marine) or
bluegill (freshwater) fish at up to 1000 mg/L. For inorganic chlorates,
RQs were not calculated for freshwater or estuarine/marine fish, since
the proximity of the LC~50~ to the highest concentration tested (1000
mg/L) could not be estimated. Although 1000 mg/L is not an LC~50~, which
is the toxicity value usually used to derive RQs, this value was used
only to estimate high-end risk to exposed fish. EECs for both
agricultural and nonagricultural uses of sodium chlorate were more than
20-fold lower than the toxic concentration observed in fish of 1000 mg/L
(all RQs would be less than 0.05, and below the Agency's acute LOC of
0.5 and the acute endangered species LOC of 0.05). Therefore, acute risk
to freshwater and estuarine/marine fish is not of concern to the Agency.

No chronic toxicity studies in fish have been submitted to the Agency,
nor were any identified in the ECOTOX database. However, the Agency will
require data to address this area of uncertainty.

**2. Aquatic Invertebrates**

For freshwater invertebrates, acute RQs are based on the EC~50~ of 920
mg/L (*daphnids*) and EECs calculated by GENEEC-2; these are presented
in Table 21 below. All RQs are below the acute LOC of 0.5 and the
endangered species acute LOC of 0.05; therefore, acute risk to
freshwater invertebrates is not of concern to the Agency.

  ----------------------------------------------------------------------------
  **Table 21. Acute                                                
  Freshwater Aquatic                                               
  Invertebrate Risk                                                
  Quotients**                                                      
  ------------------ ----------------- --------------- ----------- -----------
  **Use**            **Application     **Maximum EEC** **EC50**    **RQ**
                     Rate Range**                                  

  Agricultural uses  4.5--7.5 lb ai/A  0.91 mg/L       920 mg/L    \<0.01

  Non-agricultural   132--520 lb ai/A  39 mg/L         920 mg/L    \<0.042
  uses                                                             
  ----------------------------------------------------------------------------

For saltwater invertebrates, acute RQs were not calculated, because the
proximity of the LC~50~ from a supplemental 96-hr study (*mysid* shrimp)
to the highest concentration tested (1000 mg/L), could not be estimated.
However, the ratios of chlorate's EECs (agricultural and nonagricultural
uses) to the concentration of 1000 mg/L were calculated, and the highest
resulting value was 0.04. As this is well below the acute LOC of 0.5, in
addition to the endangered species acute LOC of 0.05, acute risk to
saltwater invertebrates is not of concern to the Agency.

Chronic risk to invertebrates was not assessed, since treatment-related
effects were not observed at any concentration in available studies.

**3. Aquatic Plants**

Toxicity (EC~50~) and exposure (EEC) values, as well as RQs, for
non-endangered aquatic plants are shown in Tables 22. For non-endangered
aquatic plants, the Agency calculates RQs by dividing EECs by EC~50~
values.~.~ For sodium chlorate, the LOC (1.0) was not exceeded for
either the agricultural or nonagricultural uses of chlorate; therefore,
risk to non-endangered aquatic plants is not of concern to the Agency.

  ------------------ ------------ ----------- ------------ ----------- ------------
  **Table 22. Risk                                                     
  Quotients for                                                        
  Non-endangered                                                       
  Aquatic Plants**                                                     

  **Use**            **Maximum    **Algal     **Duckweed   **Algal     **Duckweed
                     Peak EEC**   EC~50~**    EC~50~**     RQ**        RQ**

  Agricultural       Up to0.9  133 mg/L    43 mg/L      \<0.01      0.02
                     mg/L                                              

  Non-agricultural   Up to 39     133 mg/L    43 mg/L      Up to 0.29  0.91
                     mg/L                                              
  ------------------ ------------ ----------- ------------ ----------- ------------

The RQs for endangered aquatic plants are presented in Table 23. The
Agency calculates RQs for endangered aquatic plants by dividing EECs by
NOAECs~.~ For endangered aquatic plants, the Agency's LOC (1.0) was
exceeded for sodium chlorate's non-agricultural uses (RQ = 12.6).
However, the EECs for the non-agricultural use sites are likely
conservative; therefore, additional information on use patterns would
allow for characterization of potential risks to aquatic plants. Also,
testing on three additional required plant species is required for
herbicides. Overall, additional data are needed to allow for a full
characterization of potential risk to aquatic plants.

  ---------------------------------------------------------------------------------
  **Table 23.                                                          
  Endangered Species                                                   
  Algal Risk                                                           
  Quotients                                                            
  Agricultural and                                                     
  Non-Agricultural                                                     
  Uses**                                                               
  ------------------ ------------ ----------- ------------ ----------- ------------
  **Use**            **Maximum    **Algal     **Duckweed   **Algal     **Duckweed
                     Peak EEC**   EC~50~**    EC~50~**     RQ**        RQ**

  Agricultural       Up to 0.9    62.5 mg/L   3.1 mg/L     Up to 0.014 Up to 0.29
                     mg/L                                              

  Non-Agricultural   Up to 39     62.5 mg/L   3.1 mg/L     Up to 0.62  Up to 12.6
                     mg/L                                              
  ---------------------------------------------------------------------------------

**c. Endangered Species**

The Agency's screening level assessment results in the determination
that sodium chlorate will have no acute risks to birds, no acute risks
to fish (freshwater and estuarine/marine), and no acute or chronic risks
to aquatic invertebrates (freshwater and estuarine/marine).

However, the preliminary risk assessment for endangered species
indicates that RQs exceed endangered species LOCs for chronic risks to
birds (RQs up to 11 for agricultural uses and greater for
non-agricultural uses); acute risks to mammals (RQs up to 33); chronic
risks to mammals (RQs up to 1.2 for agricultural uses and greater for
non-agricultural uses); and risks to aquatic plants (RQs up to 13).
Risks could not be calculated for terrestrial plants and for chronic
risks to fish; however, the Agency will be requiring data.

Further, potential indirect effects to any species dependent upon a
species that experiences effects from use of sodium chlorate can not be
precluded based on the screening level ecological risk assessment. These
findings are based solely on EPA's screening level assessment and do not
constitute "may affect" findings under the Endangered Species Act.

**d. Ecological Incidents**

A review of the Ecological Incident Information System (EIIS) database
for ecological incidents involving chlorate was completed on October 25,
2004. There were no chlorate incidents in the database

[]{#__RefHeading___Toc140567155 .anchor}**IV. Risk Management,
Reregistration, and Tolerance Reassessment**

[]{#__RefHeading___Toc140567156 .anchor}**A. Determination of
Reregistration Eligibility**

Number range CHAPTER Section 4(g)(2)(A) of FIFRA calls for the Agency to
determine, after submission of relevant data concerning an active
ingredient, whether or not products containing the active ingredient are
eligible for reregistration. The Agency has previously identified and
required the submission of the generic (i.e., active
ingredient-specific) data required to support reregistration of products
containing sodium chlorate as an active ingredient. The Agency has
completed its review of these generic data, and has determined that the
data are sufficient to support reregistration of all products containing
sodium chlorate.

The Agency has completed its assessment of the dietary, occupational,
residential, and ecological risk associated with the use of pesticide
products containing the active ingredient sodium chlorate. Based on a
review of these data and on public comments on the Agency's assessments
for the active ingredient sodium chlorate, the Agency has sufficient
information on the human health and ecological effects to make decisions
as part of the tolerance reassessment process under FFDCA and
reregistration process under FIFRA, as amended by FQPA. The Agency has
determined that sodium chlorate-containing products are eligible for
reregistration provided that: (i) the risk mitigation measures outlined
in this document are adopted, (ii) label amendments are made to reflect
these measures, and (iii) a safety finding can be made for sodium
chlorite. Label changes are described in Section V. Appendix A
summarizes the uses of sodium chlorate that are eligible for
reregistration. Appendix B identifies the generic data requirements that
the Agency reviewed as part of its determination of reregistration
eligibility of sodium chlorate, and lists the submitted studies that the
Agency found acceptable. Data gaps are identified as generic data
requirements that have not been satisfied with acceptable data.

Based on its evaluation of sodium chlorate, the Agency has determined
that sodium chlorate products, unless labeled and used as specified in
this document, would present risks inconsistent with FIFRA. Accordingly,
should a registrant fail to implement any of the risk mitigation
measures identified in this document, the Agency may take regulatory
action to address the risk concerns from the use of sodium chlorate. If
all changes outlined in this document are incorporated into the product
labels, then all current risks for sodium chlorate will be adequately
mitigated for the purposes of this determination under FIFRA. Once an
Endangered Species assessment is completed, further changes to these
registrations may be necessary as explained in Section III.B.2.c. of
this document.

[]{#__RefHeading___Toc140567157 .anchor}**B. Public Comments and
Responses**

Through the Agency's public participation process, EPA worked with
stakeholders and the public to reach the regulatory decisions for sodium
chlorate. EPA released its sodium chlorate preliminary risk assessments
for public comment on February 1, 2006, for a 60-day public comment
period (Phase 3 of the public participation process). During the public
comment period on the risk assessments, which closed on April 3, 2006,
the Agency received comments from the sodium chlorate task force,
technical registrants, and private citizens. These comments in their
entirety, responses to the comments, as well as the preliminary and
revised risk assessments, are available in the public docket
(OPP-2005-0507) at http:www.regulations.gov.

[]{#__RefHeading___Toc140567158 .anchor}**C. Regulatory Position**

[]{#__RefHeading___Toc140567159 .anchor}**1. Food Quality Protection Act
Findings**

**a. "Risk Cup" Determination**

As part of the FQPA tolerance reassessment process, EPA assessed the
risks associated with this pesticide. The Agency has determined that, if
the mitigation described in this document is adopted and labels are
amended, and a safety finding can be made for sodium chlorite, human
health risks as a result of exposures to sodium chlorate are within
acceptable levels. In other words, EPA has concluded that the exemptions
from tolerances for sodium chlorate meet FQPA safety standards. In
reaching this determination, EPA has considered the available
information on the special sensitivity of infants and children, as well
as exposures to sodium chlorate from all possible sources.

**b. Determination of Safety to U.S. Population**

Number range CHAPTER The Agency has determined that provided a safety
finding can be made for sodium chlorite, the Agency has determined that
the established tolerance exemptions for sodium chlorate, with
amendments and changes as specified in this document, meet the safety
standards under the FQPA amendments to section 408(b)(2)(D) of the
FFDCA, and that there is a reasonable certainty no harm will result to
the general population or any subgroup from the use of sodium chlorate.
In reaching this conclusion, the Agency has considered all available
information on the toxicity, use practices and exposure scenarios, and
the environmental behavior of sodium chlorate. As discussed in Section
III, the acute, chronic, and cancer dietary (food and drinking water)
risks from sodium chlorate are below the Agency's acute and chronic LOC,
provided that mitigation measures outlined in this document are adopted
and labels are amended.

**c. Determination of Safety to Infants and Children**

Number range CHAPTER

EPA has determined that the established tolerance exemptions for sodium
chlorate, with amendments and changes as specified in this document, and
provided that a safety finding can be made for sodium chlorite, meet the
safety standards under the FQPA amendments to section 408(b)(2)(C) of
the FFDCA, that there is a reasonable certainty of no harm for infants
and children. The safety determination for infants and children
considers factors on the toxicity, use practices and environmental
behavior noted above for the general population, but also takes into
account the possibility of increased dietary exposure due to the
specific consumption patterns of infants and children, as well as the
possibility of increased susceptibility to the toxic effects of sodium
chlorate residues in this population subgroup.

In determining whether or not infants and children are particularly
susceptible to toxic effects from exposure to residues of sodium
chlorate, the Agency considered the completeness of the hazard database
for developmental and reproductive effects, the nature of the effects
observed, and other information. On the basis of this information, the
FQPA SF has been reduced to 1X for sodium chlorate*.* The rationale for
the decisions on the FQPA SF can be found in Section III and the
following document: *HED Chapter of the Reregistration Eligibility
Decision Document (RED),* dated January 26, 2006.

[]{#__RefHeading___Toc140567160 .anchor}**2. Endocrine Disruptor
Effects**

Number range CHAPTER

EPA is required under the FFDCA, as amended by FQPA, to develop a
screening program to determine whether certain substances (including all
pesticide active and other ingredients) "may have an effect in humans
that is similar to an effect produced by a naturally occurring estrogen,
or other endocrine effects as the Administrator may designate."
Following recommendations of its Endocrine Disruptor Screening and
Testing Advisory Committee (EDSTAC), EPA determined that there was a
scientific basis for including, as part of the program, the androgen and
thyroid hormone systems, in addition to the estrogen hormone system. EPA
also adopted EDSTAC\'s recommendation that EPA include evaluations of
potential effects in wildlife. For pesticides, EPA will use FIFRA and,
to the extent that effects in wildlife may help determine whether a
substance may have an effect in humans, FFDCA authority to require the
wildlife evaluations. As the science develops and resources allow,
screening for additional hormone systems may be added to the Endocrine
Disruptor Screening Program (EDSP).

The available toxicity studies on sodium chlorate demonstrate the
thyroid gland to be its target of toxicity. The endpoints selected to
assess chronic dietary risk and short- and intermediate-term oral and
inhalation risks in this document are protective of the observed thyroid
effects seen in the available toxicity studies. When additional
appropriate screening and/or testing protocols being considered under
the Agency's EDSP have been developed, sodium chlorate may be subjected
to further screening and/or testing to better characterize effects
related to endocrine disruption.

[]{#__RefHeading___Toc140567161 .anchor}**3. Cumulative Risks**

The FFDCA, as amended by the FQPA, requires that the Agency consider
"available information" concerning the cumulative effects of a
particular pesticide's residues and "other substances that have a common
mechanism of toxicity." The reason for consideration of other substances
is due to the possibility that low-level exposures to multiple chemical
substances that cause a common toxic effect by a common toxic mechanism
could lead to the same adverse health effect as would a higher level of
exposure to any of the substances individually. The EPA has not made a
common mechanism of toxicity finding as to sodium chlorate and any other
substances. For the purposes of this reregistration eligibility decision
(RED), therefore, EPA has not assumed that the inorganic chlorates have
a common mechanism of toxicity with other substances. For information
regarding EPA's efforts to determine which chemicals have a common
mechanism of toxicity and to evaluate the cumulative effects of such
chemicals, see the policy statements released by EPA's Office of
Pesticide Programs concerning common mechanism determinations and
procedures for cumulating effects from substances found to have a common
mechanism on EPA's website at http://www.epa.gov/pesticides/cumulative/.

[]{#__RefHeading___Toc140567162 .anchor}**4. Endangered Species**

The Agency's screening-level assessment results in the determination
that sodium chlorate will have no acute risks to birds, no acute risks
to fish (freshwater and estuarine/marine), and no acute or chronic risks
to aquatic invertebrates (freshwater and estuarine/marine).

However, the preliminary risk assessment for endangered species
indicates that RQs exceed endangered species LOCs for chronic risks to
birds (RQs up to 11 for agricultural uses and greater for
non-agricultural uses); acute risks to mammals (RQs up to 33); chronic
risks to mammals (RQs up to 1.2 for agricultural uses and greater for
non-agricultural uses); and risks to aquatic plants (RQs up to 13).
Risks could not be calculated for terrestrial plants and for chronic
risks to fish; however, the Agency will be requiring data.

Further, potential indirect effects to any species dependent upon a
species that experiences effects from use of sodium chlorate cannot be
precluded based on the screening-level ecological risk assessment. These
findings are based solely on EPA's screening-level assessment and do not
constitute "may affect" findings under the Endangered Species Act.

The Agency has developed the Endangered Species Protection Program to
identify pesticides whose use may cause adverse impacts on endangered
and threatened species, and to implement mitigation measures that
address these impacts. The Endangered Species Act (ESA) requires federal
agencies to ensure that their actions are not likely to jeopardize
listed species or adversely modify designated critical habitat. To
analyze the potential of registered pesticide uses that may affect any
particular species, EPA uses basic toxicity and exposure data developed
for the REDs and considers it in relation to individual species and
their locations by evaluating important ecological parameters, pesticide
use information, geographic relationship between specific pesticide uses
and species locations, and biological requirements and behavioral
aspects of the particular species, as part of a refined species-specific
analysis. When conducted, this species-specific analysis will take into
consideration any regulatory changes in this RED that are being
implemented at that time.

Following this future species-specific analysis, a determination that
there is a likelihood of potential impact to a listed species or its
critical habitat may result in: limitations on the use of sodium
chlorate, other measures to mitigate any potential impact; or
consultations with the Fish and Wildlife Service or the National Marine
Fisheries Service as necessary. If the Agency determines use of sodium
chlorate "may affect" listed species or their designated critical
habitat, EPA will employ the provisions in the Services regulations (50
CFR Part 402). Until that species-specific analysis is completed, the
risk mitigation measures being implemented through this RED will reduce
the likelihood that endangered and threatened species may be exposed to
sodium chlorate at levels of concern. EPA is not requiring specific
sodium chlorate label language at the present time relative to
threatened and endangered species. If, in the future, specific measures
are necessary for the protection of listed species, the Agency will
implement them through the Endangered Species Protection Program.

[]{#__RefHeading___Toc140567163 .anchor}**D. Tolerance Reassessment
Summary**

Table 24 summarizes the reassessment of the sodium chlorate tolerance
exemptions pending a safety finding can be made for sodium chlorite. 40
CFR must be updated to reflect the tolerance exemptions in the table
below. The tolerance exemptions listed in 40 CFR must be reorganized in
order to: (i) incorporate the recommendations made by the Agency
concerning the sodium chlorate residues of concern that need to be
regulated for plant and animal commodities; (ii) include tolerance
exemptions that are needed to cover sodium chlorate residues of concern
in/on the raw agricultural commodities and processed commodities of
rotational crops; and (iii) conform with the requirements of FQPA.

+------------+---------+------------+--------------------------------+
| **Table    |         |            |                                |
| 24.        |         |            |                                |
| Tolerance  |         |            |                                |
| Re         |         |            |                                |
| assessment |         |            |                                |
| Summary    |         |            |                                |
| for Sodium |         |            |                                |
| Chlorate** |         |            |                                |
+============+=========+============+================================+
| **Listed   |         |            |                                |
| under 40   |         |            |                                |
| CFR        |         |            |                                |
| 180        |         |            |                                |
| .1020(a)** |         |            |                                |
+------------+---------+------------+--------------------------------+
| **C        | **      | *          | **\[*Correct Definition*\]**   |
| ommodity** | Current | *Tolerance |                                |
|            | To      | Re         | **Comments**                   |
|            | lerance | assessment |                                |
|            | (ppm)** | (ppm)**    |                                |
+------------+---------+------------+--------------------------------+
| Beans,     | Exempt  | Exempt     | \[*Bean, dry, seed*\]          |
| dry,       |         |            |                                |
| edible     |         |            |                                |
+------------+---------+------------+--------------------------------+
| Corn,      | Exempt  | Exempt     | \[*Corn, field, stover; Corn,  |
| fodder     |         |            | field, forage; Corn, field,    |
|            |         |            | grain; Corn, sweet, stover;    |
|            |         |            | Corn, pop, stover; Corn, pop,  |
|            |         |            | grain; Corn, sweet, forage*\]  |
+------------+---------+------------+--------------------------------+
| Corn,      | Exempt  |            |                                |
| forage     |         |            |                                |
+------------+---------+------------+--------------------------------+
| Corn,      | Exempt  |            |                                |
| grain      |         |            |                                |
+------------+---------+------------+--------------------------------+
| Cottonseed | Exempt  | Exempt     | \[*Cotton, undelinted seed*\]  |
+------------+---------+------------+--------------------------------+
| Flaxseed   | Exempt  | Exempt     | \[*Flax, seed*\]               |
+------------+---------+------------+--------------------------------+
| Flax,      | Exempt  | Revoke     | Flax straw is not listed in    |
| straw      |         |            | Table 1 of OPPTS 860.1000      |
+------------+---------+------------+--------------------------------+
| Guar beans | Exempt  | Exempt     | \[*Guar, seed*\]               |
+------------+---------+------------+--------------------------------+
| Peas,      | Exempt  | Exempt     | \[*Pea, southern, seed*\]      |
| southern   |         |            |                                |
+------------+---------+------------+--------------------------------+
| Potatoes   | Exempt  | Exempt     | \[*Potato*\]                   |
+------------+---------+------------+--------------------------------+
| Peppers,   | Exempt  | Exempt     | \[*Pepper, nonbell*\]          |
| chili      |         |            |                                |
+------------+---------+------------+--------------------------------+
| Rice       | Exempt  | Exempt     | \[*Rice, grain; Rice, straw*\] |
+------------+---------+------------+--------------------------------+
| Rice,      | Exempt  |            |                                |
| straw      |         |            |                                |
+------------+---------+------------+--------------------------------+
| Safflower, | Exempt  | Exempt     | \[*Safflower, seed*\]          |
| grain      |         |            |                                |
+------------+---------+------------+--------------------------------+
| Sorghum,   | Exempt  | Exempt     | \[*Sorghum grain, grain;       |
| grain      |         |            | Sorghum, grain, stover;        |
|            |         |            | Sorghum, grain, forage*\]      |
+------------+---------+------------+--------------------------------+
| Sorghum,   | Exempt  |            |                                |
| fodder     |         |            |                                |
+------------+---------+------------+--------------------------------+
| Sorghum,   | Exempt  |            |                                |
| forage     |         |            |                                |
+------------+---------+------------+--------------------------------+
| Soybeans   | Exempt  | Exempt     | \[*Soybean, seed*\]            |
+------------+---------+------------+--------------------------------+
| Sunflower  | Exempt  | Exempt     | *\[Sunflower, seed*\]          |
| seed       |         |            |                                |
+------------+---------+------------+--------------------------------+
| Wheat      | None    | Exempt     | \[*Wheat, grain*\]             |
+------------+---------+------------+--------------------------------+
| **Listed   |         |            |                                |
| under 40   |         |            |                                |
| CFR        |         |            |                                |
| 180        |         |            |                                |
| .1020(b)** |         |            |                                |
+------------+---------+------------+--------------------------------+
| Wheat      | Exempt  | Revoke     | \[*Wheat, grain*\]             |
|            |         |            | Time-limited exemption         |
|            |         |            | currently expires on           |
|            |         |            | 12/31//2006                    |
+------------+---------+------------+--------------------------------+

**Existing Exemptions**

Sodium chlorate is currently registered for preharvest and foliar
applications as a defoliant or desiccant to the following food/feed
crops: beans, corn, cotton, flax, guar, chili peppers, potatoes, rice,
safflower, sorghum (grain), southern peas (*i.e.*, cowpeas), soybeans,
and sunflowers.

Sodium chlorate exemptions under 40 CFR 180.1020(a) from the requirement
of a tolerance should be amended as follows to: (1) specify defoliant
and desiccant use only, (2) specify use on crops rather than raw
agricultural commodities, and (3) include an exemption for wheat
(grain).

*40 CFR 180.1020(a) Sodium chlorate is exempt from the requirement of a
tolerance for residues when used as a defoliant or desiccant in
accordance with good agricultural practice on the following crops: Bean
(dry, seed), Corn (field, stover), Corn (field, forage), Corn (field,
grain), Corn (sweet, stover), Corn (pop, stover), Corn (pop, grain);
Corn (sweet, forage), Cotton (undilented seed), Flax (seed), Guar
(seed), Peas (southern, seed), Peppers (nonbell), Potatoes, Rice
(grain), Rice (straw), Safflower (seed), Sorghum (grain, grain), Sorghum
(grain, stover), Sorghum (grain, forage), Soybean (seed), and Sunflower
(seed).*

Under 40 CFR 180.1020(b), a time-limited exemption from the requirement
of a tolerance is established for residues of the defoliant/desiccant in
connection with use of the pesticide under section 18 emergency
exemptions granted by EPA. This exemption was granted for wheat and
expires 12/31/06. The use of sodium chlorate on wheat is also addressed
herein with the intention to convert the time-limited exemption status
to a permanent exemption from the requirement of a tolerance under 40
CFR.1020 (a). The proposed use rate is for a single application of
sodium chlorate to wheat at 6 lbs ai/A with a 3-day PHI.

**Needed Exemptions**

Sodium chlorate (873301) as an inert ingredient in herbicide formulation
products can be applied professionally to agricultural (corn, guava,
macadamia nuts, sorghum grain, sugarcane, wheat), commercial
(non-agricultural), and residential sites. These conventional pesticide
products contain \< 1 % sodium chlorate and can be applied at rates no
greater than 0.07 lb (as sodium chlorate) per acre.

Potassium chlorate (900583) as an inert ingredient in fungicide products
can be applied in poultry premises. These conventional pesticide
products contain \< 20% potassium chlorate and can be applied at rates
not greater than 0.01 lb (as potassium chlorate) per 500 ft^3^. See
Table 25 below for the tolerance exemptions needed for sodium chlorate.

[]{.mark}

+-------------------+---------+---------+---------+---------+---------+
| **Table 25.       |         |         |         |         |         |
| Tolerance         |         |         |         |         |         |
| Exemptions Needed |         |         |         |         |         |
| for sodium        |         |         |         |         |         |
| chlorate**        |         |         |         |         |         |
+-------------------+---------+---------+---------+---------+---------+
| **Tolerance       | **PC    | **CAS   | **40    | **Use** | **List  |
| Exemption         | Code**  | Reg     | CFR §** |         | Cl      |
| Expression**      |         | No.**   |         | **      | assific |
|                   |         |         |         | (Pestic | ation** |
|                   |         |         |         | idal)** |         |
+-------------------+---------+---------+---------+---------+---------+
| Sodium chlorate   | 873301  | 77      | 180.920 | Sta     | 3       |
|                   |         | 75-09-9 | ^1^     | bilizer |         |
+-------------------+---------+---------+---------+---------+---------+
| Potassium         | 900583  | 38      | 180.930 | O       | 3       |
| chlorate          |         | 11-04-9 | ^2^     | xidizer |         |
+-------------------+---------+---------+---------+---------+---------+

1\. Residues listed in 40 CFR §180.920 \[formerly 40 CFR§ 180.100(d)\]
are exempted from the requirement of a

tolerance when used in accordance with good agricultural practice as
inert (or occasionally active) ingredients in

pesticide formulations applied to growing crops only.

2\. Residues listed in 40 CFR §180.930 \[formerly 40 CFR§ 180.100(e)\]
are exempted from the requirement of a

tolerance when used in accordance with good agricultural practice as
inert (or occasionally active) ingredients in

pesticide formulations applied to animals.

[]{.mark}

**Codex/International Harmonization**

There are no Codex maximum residue limits (MRLs) for sodium chlorate.

[]{#__RefHeading___Toc140567164 .anchor}**E. Regulatory Rationale**

The following is a summary of the rationale for managing risks
associated with the use of sodium chlorate for sodium chlorate products
to be eligible for reregistration. Where labelling revisions are
warranted, specific language is set forth in Table 28 of Section V.

[]{#__RefHeading___Toc140567165 .anchor}**1. Human Health Risk
Management**

**a. Dietary (Food) Risk Mitigation**

[Acute Dietary (Food) Risk]{.underline}

No acute dietary endpoint was selected for sodium chlorate, because
effects attributable to a single dose were not seen in the available
data. Therefore, dietary acute risk is not of concern to the Agency, and
no mitigation measures are required to address acute risk.

[Chronic Dietary (Food) Risk]{.underline}

The chronic dietary risk assessment for food only is below the Agency's
level of concern (LOC) for the general US population and all population
subgroups. The most highly exposed population subgroup, children 1-2
years of age, was at 28% of the chronic Population Adjusted Dose (cPAD).
Since this is less than 100% of the cPAD, no mitigation is needed.

**b. Residential Risk Mitigation**

All residential (non-occupational) handler and post-application risk
estimates for inorganic chlorates, as active or inert ingredients in
conventional pesticide products used in residential environments, are
below the Agency's LOC (*i.e.*, MOEs are greater than the LOC of 100).
The handler inhalation MOEs ranged from 370 to 710,000. The
post-application combined MOE (for inert ingredients) was 23,000 for all
potential routes of exposure to children; therefore, no residential
mitigation is necessary.

**c. Aggregate Risk Mitigation**

As discussed in Section III of this RED, aggregate risk refers to the
combined risk from food, drinking water, and residential exposures.
Aggregate risk can result from one-time (acute), short-term and/or
chronic exposures.

[Acute Aggregate Risk]{.underline}

For sodium chlorate, acute aggregate risk was not assessed, because
effects attributable to a single dose were not seen in the available
data. Therefore, acute aggregate risk is not of concern to the Agency.

[Short-Term Aggregate Risk]{.underline}

Short-term aggregate risk was quantitatively assessed for adults only,
using the highest exposure scenario (inhalation exposure while applying
granules by hand) resulting in an MOE of 324. Short-term aggregate risk
for children was qualitatively assessed and not of concern to the Agency
because the short-term residential risk to children from the use of
sodium chlorate as an inert is minimal (MOE of 23,000). All short-term
aggregate risks are below the Agency's LOC (*i.e.*, MOEs are greater
than 100); therefore, no mitigation is necessary.

[Chronic Aggregate Risk]{.underline}

Since no chronic residential (non-dietary) exposure scenarios have been
identified for sodium chlorate, the chronic aggregate risk assessment
considers exposure only through food and drinking water. The Agency
believes there is no chronic risk of concern, for the US general
population or any subpopulation group, for the reasons described below.

The chronic dietary (water only) risk assessment for chlorate in
drinking water, using the highest annual average concentration from ICR
data of 0.69 mg/L, is below the Agency's level of concern for the
general US population and all subgroups except all infants \<1 year of
age. The highest exposed population subgroup, all infants \<1 year of
age, was 159% of the cPAD. Using the 90th percentile annual average
concentration of 0.24 mg/L, the chronic dietary (water only) risk for
all infants \<1 year of age was \<55% of the cPAD; using the median
annual average concentration estimated at 0.11 mg/L, estimated chronic
risk from drinking water was 25% of the cPAD. The contribution of
exposure from food sources increases total dietary risk (food + drinking
water) to 174% of the cPAD for infants \<1 year of age at the highest
annual average, but remains below EPA's level of concern at the 90^th^
percentile (70% of the cPAD).

Data on the occurrence of chlorate ion in drinking water were available
from two primary sources: the Information Collection Rule (ICR)
Auxiliary 1 Database, Version 5.0, and the AwwaRF research study on the
control of chlorate ion in hypochlorite solutions. The most extensive
data are from the ICR where source water and drinking water were
monitored for chlorate ion between July 1997 and December 1998. Water
systems serving a population of at least 100,000 were required to
monitor for chlorate ion at treatment plants using chlorine dioxide or
hypochlorite solutions in the treatment process. Although the ICR water
systems represent roughly one percent of the total number of drinking
water systems in the United States, these systems serve almost 60% of
the population. Under the ICR, plants using chlorine dioxide collected
monthly samples of the source water entering the plant, the finished
water leaving the plant, and at three sample points in the distribution
system (near the first customer, an average residence time, and a
maximum residence time). Samples were taken throughout the distribution
systems for plants using chlorine dioxide, since the concentration of
chlorate is expected to change within the system due to the conversion
of chlorine dioxide to chlorate that occurs in the presence of chlorine.
Plants using hypochlorite solutions were required to collect quarterly
samples of the water entering and leaving the plant.

The AwwaRF data consists of samples collected in 1993 by 111 water
treatment plants using hypochlorite. The majority of the systems in the
AwwaRF project serve populations less than 100,000, and a large subset
of those serve populations less than 10,000. Samples of source water,
hypochlorite solution, and finished drinking water from 111 of water
systems were analyzed for chlorate. Only one set of samples was
collected for each system, and samples were not collected at plants
using chlorine dioxide. Furthermore, the background information on the
111 water systems that participated in the project was not linked to the
samples they provided; therefore, the chlorate concentrations can not be
directly related to the size of the water system or type of hypochlorite
solution in use.

The AwwaRF samples were typically found to have higher concentrations of
chlorate than the samples collected from the larger ICR systems. The
difference in chlorate concentrations could be the result of a number of
factors, such as: 1) The AwwaRF data represents a single point in time,
while the ICR data reflects an average over 18 months; 2) most of the
AwwaRF samples were collected from utilities that served populations of
less that 100,000, while all of the ICR samples were from utilities
serving at least 100,000; and 3) hypochlorite treatment plant practices
may have changed between when the AwwaRF samples were collected (1993)
and the ICR samples were collected (1997-1998). When the AwwaRF study
was conducted, utilities were just becoming aware of the formation of
chlorate ion in hypochlorite solutions. The AwwaRF project was funded in
order to provide water treatment facilities with information on how to
minimize the formation of chlorate byproduct; it is possible that
facilities consequently revised their treatment practices.

The ICR Database was considered the more appropriate source for
estimating exposure averages from individual water treatment plants,
primarily because the AwwaRF study is a less robust data set consisting
of only one sample per utility, whereas the ICR database collected
multiple samples over an 18 month period, from plants using both
hypochlorite and chlorine dioxide. Both the AwwaRF study and the ICR
data reveal high concentrations of chlorate ion to be a local situation
affecting a relatively small number of systems. Of the ICR data set,
only four water treatment plants had average chlorate ion concentrations
that exceeded the Agency's level of concern (i.e., 370 ppb or 0.37 mg/L,
for the infant subpopulation) including one treatment plant serving
218,000 people that had the highest annual average (0.69 mg/L). Of the
four plants that exceeded, two treatment plants used chlorine dioxide,
and two used hypochlorite. The total number of people served by the four
water treatment plants exceeding 0.37 mg/L represents 0.5% of the ICR
population, or 621,000 people. All three exposure ranges (highest
average, 90^th^ percentile, and median) are presented in Section III.
Only the "highest average" exposures resulted in potential chronic risk
estimates that were above the Agency's LOC, and only for infants. Over
99% of the ICR population receives finished water below the Agency's LOC
of 0.37 mg/L.

The chlorate ion (ClO ~3~^-^) is a disinfection byproduct (DBP) of water
treatment which can be formed during the on-site generation of chlorine
dioxide (ClO ~2~^-^), the decomposition of chlorine dioxide in the water
treatment system, the decomposition of hypochlorite (OCl^-^) during
storage, and the interaction of chlorite ion and free chlorine.
Treatment of public water supplies is necessary to kill pathogens that
may exist in the drinking water, such as cholera, typhoid, and
dysentery. Outbreaks of these diseases decreased significantly when
disinfection of the water systems was introduced in the early 1900s.
While there are many important public functions of water treatment, the
Agency is taking steps to limit the exposure of chlorate ion as a DBP to
the public.

In order to help reduce potential exposure to chlorate, the Agency's
Office of Pesticide Programs (OPP), in conjunction with the Office of
Water (OW), is working with the American Water Works Association (AWWA),
the Chlorine Institute, and individual water communities to provide
community water systems with information on Best Management Practices
(BMPs) for use in drinking water treatment. BMPs may include measures
such as production modifications, operational changes, materials
substitution, materials and water conservation, and other such measures.
For example, water systems that use hypochlorite solutions can minimize
the levels of chlorate ion by purchasing high quality hypochlorite
solutions and through careful storage during use. While decomposition of
hypochlorite solutions cannot be avoided, the rate of decomposition can
be managed. Among the major factors affecting stability are the
following: concentration of the hypochlorite solution, temperature of
the solution, pH of the solution, and exposure to light sources. The pH
of the solution should be in the 12 to 13 range to minimize
decomposition. Hypochlorite solutions should be protected from high
temperatures and sunlight, and storage time should be minimized, both
from the time of manufacture to delivery, and from the time of delivery
to use. The solutions can also be diluted to control decomposition as
long as the proper pH is maintained and high quality dilution water is
used. The primary ways in which water systems using chlorine dioxide can
control the levels of chlorate in the finished water is through high
efficiency operation of their chlorine dioxide generators and by
reducing chlorite ion concentrations prior to the addition of free
chlorine. The BMPs could also include additional training of the water
systems employees on the proper handling of these chemicals.

The Agency believes that sodium chlorate does not constitute a risk of
concern to the general population or any population subgroups, since the
LOC exceedances are associated with a small number of water treatment
facilities and inappropriate treatment practices. Furthermore, the
Agency anticipates that the community water system outreach strategy
previously discussed will greatly reduce potential drinking water
byproduct exposure.

**d. Occupational Risk Mitigation**

With the consideration of mitigation measures proposed by registrants
and the use of engineering controls (enclosed cockpits or cabs), all
occupational handler risks for the use of inorganic chlorates as an
active or inert ingredient in conventional pesticides are below the
Agency's LOC (*i.e.*, MOEs are greater than the LOC of 100). For sodium
chlorate, occupational exposure durations are short- (1-30 days) and
intermediate term (1-6 months) only. Long-term (\> 6 months) exposure is
not expected based on the use pattern for sodium chlorate.
Post-application dermal and inhalation exposures are negligible due to
the chemical's physical and chemical characteristics as an inorganic
salt. No significant amount of sodium chlorate is expected to be
absorbed through the skin and the vapor pressure is negligible;
therefore, a post-application exposure assessment was not conducted.

[Antimicrobial Uses of Sodium Chlorate]{.underline}

Risks to handlers treating water systems are below the Agency's LOC;
therefore, no mitigation measures are necessary.

[Agricultural Uses of Sodium Chlorate]{.underline}

With the exception of aerial applications, for which enclosed cockpits
are required, the handler and flagger MOEs for sodium chlorate's
agricultural uses are below the Agency LOC at baseline level of
protection (long sleeve shirt, long pants, shoes, and socks). MOEs range
from 190 (mixing/loading liquids for aerial application on cotton, corn,
et al.) to 3600 (mixing/loading liquids for groundboom application on
ornamental gourds and cucurbits). Further, the maximum application rate
for use on cotton will be reduced from 7.5 lbs ai/A to 6 lbs ai/A, with
a limitation of one application (except for California, where two
applications will be allowed). No additional mitigation is required for
occupational risk resulting from the agricultural uses of sodium
chlorate.

[Non-agricultural Uses of Sodium Chlorate]{.underline}

The Agency's review of sodium chlorate labels, in addition to
discussions with registrants, indicates that the current
non-agricultural use labels are not reflective of actual use practices.
The non-agricultural use labels currently allow for larger application
rates than are necessary for efficacy, as well as allow for unlimited
treatment areas, although sodium chlorate's non-agricultural
formulations are typically used as spot treatments.

Mitigation measures for sodium chlorate's non-agricultural uses to be
included on product labels will reduce risk from the occupational and
ecological exposures to sodium chlorate. The registrants have agreed to
the following non-agricultural use mitigation measures for sodium
chlorate:

-   All non-agricultural uses will be limited to spot treatments only
    (with the exception of the granular formulation for use under
    asphalt, although this use will be limited to an 8000 ft^2^
    treatment area). The uses limited to spot treatments include, but
    are not limited to: building perimeters (including farm buildings),
    driveways, parking lots, fence rows, military installations,
    pipelines, railroads, lumberyards, industrial sites (transformers,
    generators, utility poles, etc.), tennis court perimeters, picnic
    areas, bleachers, cemeteries, fuel tanks, airport runways, helo
    pads, wood decks, guard rails, highway medians, sidewalks/walkways,
    vacant lots, fire hydrants, recreational areas, and other similar
    areas.

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-   Use on rights-of-way and ditch banks will be cancelled.

-   The label will specify a maximum application rate of 0.9 lb ai/100
    ft^2^

The Agency generally converts application rates to a per acre basis for
assessment purposes; therefore, the rate of 0.9 lb ai/100 ft^2^ is
referred to as 392 lb ai/A in this document. However, because all
non-agricultural uses will be limited to spot treatment applications
only, all 392 pounds of a.i. will not be applied on any one given acre.
Assuming only one acre is considered for treatment, sodium chlorate can
only be applied to up to 8000 ft^2^, which equates to up to
approximately 78 lbs ai being applied to any given acre. It is assumed
that more than one acre will be treated.

Risk calculations have been developed to better represent the current,
actual use pattern for sodium chlorate, and occupational risk was
reassessed based on the revised use pattern discussed above (i.e.,
application rates, target sites, and amount treated). Following is a
summary of the *Inorganic Chlorates: Addendum to the Occupational and
Residential Exposure Assessment for the Reregistration Eligibility
Decision (RED) Document*, dated May 18, 2006.

All data, factors, and assumptions used in the addendum are the same as
those used in the previous occupational risk assessment. These include,
but are not limited to:

-   body weight (70 kg representing adult handlers);

-   toxicological endpoints (short-/intermediate-term oral NOAEL of 30
    mg/kg/day) and uncertainty factors (Level of Concern (LOC) for the
    MOE is 100);

-   application rates (in lb ai/A -- presented as a range to encompass
    the various registered products); and,

-   unit exposures (from PHED and/or ORETF database, both of which have
    undergone appropriate review by the Human Studies Review Board).

However, factors regarding application equipment used and daily area
treated were revised based on updated use pattern information and
proposed product label revisions. The previous assessment, summarized in
Section III, was based on applications with larger, industrial equipment
such as tractor spreaders or groundboom sprayers. As a result of
mitigation measures agreed to by the technical registrants, sodium
chlorate applications to non-agricultural areas (*i.e.*, building
perimeters, ditch banks, bleachers, airport runways, vacant lots, fire
hydrants, or as a pre-paving treatment) will be limited to "handheld"
equipment such as rotary spreaders and pump or power sprayers. In
addition, the standard Agency assumptions for the amount applied per
work day is based on the application equipment used to determine
exposure and risk. Since submitted information indicates that no more
than 8,000 ft^2^ of an acre (approximately 20%) will be treated with
sodium chlorate, the Agency has adjusted the standard assumptions for
acres treated per day to reflect this spot treatment-type scenario.

Based on the revised assumptions for the daily area treated and on
application methods suitable for spot treatments (low-pressure handwand
sprayers, belly grinders, push-type spreaders), the risks for all
non-agricultural uses, even at the currently labeled application rate
(523 lbs ai/A instead of 392 lb ai/A), are below the Agency LOC. The
higher application rate of 523 lb ai/A was used, because at the time the
*Inorganic Chlorates: Addendum to the Occupational and Residential
Exposure Assessment for the Reregistration Eligibility Decision (RED)
Document*, dated May 18, 2006, was prepared, the 392 lb ai/A maximum
application rate mitigation measure was not yet finalized. The
mitigation measures outlined above reduce the occupational risk from all
of sodium chlorate's non-agricultural uses to below the Agency's level
of concern at baseline level of protection (long sleeve shirt, long
pants, shoes, and socks). The risks based on the revised
non-agricultural use patterns for sodium chlorate are summarized in
Table 26 below.

+-----------------+----------+-----------------+----------+----------+
| **Table 26:     |          |                 |          |          |
| Sodium          |          |                 |          |          |
| Chlorate:       |          |                 |          |          |
| Short- and      |          |                 |          |          |
| In              |          |                 |          |          |
| termediate-Term |          |                 |          |          |
| Occupational    |          |                 |          |          |
| Inhalation      |          |                 |          |          |
| Exposure**      |          |                 |          |          |
+=================+==========+=================+==========+==========+
| **Exposure      | **Daily  | **Crop/Target** | **App    | **In     |
| Scenario**      | Area     |                 | lication | halation |
|                 | Treated  |                 | Rate**   | MOE**    |
|                 | (Acre    |                 |          |          |
|                 | s/day)** |                 | **(lbs   | **(at    |
|                 |          |                 | ai/Ac    | bas      |
|                 |          |                 | re)^a^** | eline)** |
+-----------------+----------+-----------------+----------+----------+
| **Mixer/Loa     |          |                 |          |          |
| der/Applicators |          |                 |          |          |
| &               |          |                 |          |          |
| Loade           |          |                 |          |          |
| r/Applicators** |          |                 |          |          |
+-----------------+----------+-----------------+----------+----------+
| Mixing/L        | 0.4      | Indu            | 523      | 330      |
| oading/Applying |          | strial/Non-Crop |          |          |
| liquids with a  |          | Sites           |          |          |
| low- pressure   |          |                 |          |          |
| handwand        |          |                 |          |          |
| sprayer         |          |                 |          |          |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 132      | 1300     |
+-----------------+----------+-----------------+----------+----------+
| M/L/A liquids   | 1        | Indu            | 523      | 2200     |
| with a handgun  |          | strial/Non-Crop |          |          |
| sprayer         |          | Sites           |          |          |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 132      | 8800     |
+-----------------+----------+-----------------+----------+----------+
| L/A granules    | 0.2      | Indu            | 523      | 320      |
| with a belly    |          | strial/Non-Crop |          |          |
| grinder         |          | Sites           |          |          |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 240      | 710      |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 161      | 1100     |
+-----------------+----------+-----------------+----------+----------+
| L/A granules    | 1        | Indu            | 523      | 550      |
| with a          |          | strial/Non-Crop |          |          |
| push-type       |          | Sites           |          |          |
| spreader        |          |                 |          |          |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 240      | 1200     |
+-----------------+----------+-----------------+----------+----------+
|                 |          |                 | 161      | 1800     |
+-----------------+----------+-----------------+----------+----------+

a\. Application rate will be reduced to 0.9 lb ai/100 ft^2^ (392 lb
ai/A).

[]{#__RefHeading___Toc140567166 .anchor}**2. Non-Target Organism
(Ecological) Risk Management**

Chlorate is a strong oxidizer and may be reduced to other chemically
related species under some environmental conditions. The extent and rate
to which this occurs will depend on the redox chemical species
(including organic matter) in the water or soil. Extensive spatial and
temporal variability is expected for the reactions of chlorate in the
environment. However, the currently available simulation models do not
allow for a quantitative evaluation of the potential exposure levels of
each the reduced products of chlorate (i.e., speciation and
predominance) and how fast these chemical species may form. Therefore,
there is a high degree of uncertainty in the ecological exposure and
risk assessment. This is important because a reduction product of
chlorate (chlorite) is expected to be more toxic to most aquatic and
terrestrial species, particularly aquatic invertebrates.

**a. Terrestrial Organisms**

[]{.mark}

**1. Birds and Mammals**

EPA's screening-level risk assessment, based on currently labelled
maximum application rates, for both agricultural and non-agricultural
uses for sodium chlorate, suggests potential acute and chronic risk for
birds

[Avian Acute Risk]{.underline}

Avian acute risk was not calculated, since no mortality or signs of
toxicity were observed in the submitted subacute or acute toxicity
studies at concentrations that are above the limit for these types of
studies; therefore, acute risk to birds is not expected. However, the
Agency cannot preclude acute or subacute risk from the non-agricultural
uses. Some labels have maximum application rates up to 1032 lbs ai/A,
and the ecological assessment for risk from non-agricultural uses was
based on rates ranging from 52 to 523 lbs ai/A, with corresponding EECs
from 12,500 and 125,000 ppm, respectively. These EECs are approximately
2.5 to 25-fold higher than the highest concentration tested in the
subacute bird toxicity studies. The non-agricultural use mitigation
outlined above, including the reduction of the maximum application rate
to 392 lbs ai/A, and a limitation to spot treatments only (except for
use under asphalt, although this use is limited to no more than an 8000
ft^2^ area). Reducing the maximum application rate from 520 lbs ai/A to
392 lbs ai/A will reduce the estimated environmental concentrations of
chlorate by approximately 25%. Further, to the extent that there is any
potential acute risk to birds from the non-agricultural uses, the fact
that these uses will result in small contiguously treated areas could
limit avian exposure.

[Avian Chronic Risk]{.underline}

Maximum chronic RQs, based on EECs derived with 90th percentile residue
estimates from the Kenaga nomogram, exceed the Agency's avian LOC of 1.0
for all agricultural uses assessed for birds eating short grass, tall
grass, broadleaf forage, and small insects. Chronic RQs based on EECs
derived with mean residue estimates from the Kenaga nomogram, although
not presented in Section III, would be approximately three times lower
for any single application of sodium chlorate. The highest agricultural
use chronic RQ was 11 (chili peppers/white, Irish potatoes and the short
grass food category). The second highest RQs were for cotton (ranging
from 10.0 for the short grass food category, to 0.63 for fruits, pods,
seeds, and small insects). Cotton is also by far the most common
agricultural use of sodium chlorate, with approximately 1,900,000 lbs ai
applied annually.

To address the chronic risk to birds from use on cotton, the maximum
application rate will be reduced from 7.5 lbs ai/A to 6 lbs ai/A, and
applications will be limited to a single applications in all states
except California, where a second application will be allowed. This
mitigation measure will reduce chronic risk to birds from use on cotton
by approximately one- half, with RQs ranging from 5.31 (on the short
grass food category), to 0.33 (on fruits, pods, seeds, and small
insects) for all states except California. In California, the chronic
avian RQs based on the reduced maximum application rate of 6 lbs ai/A,
and two applications, will be reduced to a range of 8.25 (on the short
grass food category) to 0.52 (on fruits, pods, seeds, and small
insects).

Chronic avian RQs for sodium chlorate were based on a NOAEC of 271 ppm
from the bobwhite quail chronic reproductive toxicity test. However,
maximum EECs for a majority of the uses and classes of food items were
also higher than the LOAEC in bobwhite quail of 964 ppm. At the LOAEC,
reproductive effects occurred, including a 67% reduction in eggs laid
and 64% reduction in number of hatchlings per egg laid. Therefore, if
actual exposure is equivalent to the maximum values calculated with the
T-REX model, there is a greater certainty that frank reproductive
effects in birds might occur.

However, the duration of exposure needed to produce reproductive effects
in birds is an uncertainty. This uncertainty is significant in the case
of sodium chlorate, because as a broad-spectrum herbicide, its toxic
effects on plants are visible within several days. Since the vegetation
in the treated area will die, it is uncertain whether or not this
vegetation will be attractive to birds as a feed item long enough for
the chronic effects to occur.

Chronic RQs were not calculated for sodium chlorate's non-agricultural
uses. However, based on the high application rates and resulting high
potential EECs, risks from sodium chlorate's non-agricultural uses could
be considerably higher than those described in Section III for the
agricultural uses. The non-agricultural use mitigation outlined above,
including a reduction in the maximum labeled application rate to 0.9 lbs
ai/100 ft^2^ (392 lbs ai/A), would reduce the EECs of chlorate by
approximately 25% in the areas treated. Furthermore, the limitation of
most non-agricultural uses to spot treatments only is expected to reduce
the likelihood that a terrestrial organism will come into contact and
consume all of its diet from a treated area. However, RQs still exceed
the chronic LOC for birds (1.0). See the *Analysis of proposed changes
to sodium chlorate's application rates and maximum treated area on
potential ecological risks presented in EFED's reregistration
eligibility decision (RED) document*, dated June 13, 2006 for further
detail.

[Mammalian Acute Risk]{.underline}

Acute RQs were not calculated for mammals. The LD~50~ from a core acute
oral toxicity study in rats was \>5000 mg/kg-bw. In this study, 10%
(1/10) of the rats administered 5000 mg/kg died. Mortality was not
observed at any other dose. Therefore, the data were not sufficient to
allow for characterization of the dose-response relationship and the
proximity of the LD~50~ to 5000 mg/kg-bw is uncertain. Although RQs were
not calculated for mammals, Tables 17, 18 and 19 in Section III present
a comparison of the body weight adjusted LD~50~s to EECs for
agricultural spray, and the non-agricultural spray and granular,
formulations, respectively. These ratios can be used to estimate
high-end risk to exposed mammals. Risk quotients would be lower than the
values in Section III.

For sodium chlorate's agricultural uses, all of the mammalian acute risk
estimates are below the Agency's acute and endangered species LOC of 1.0
and 0.1, respectively, with the exception of small mammals eating short
grass. The highest exceedence is for 15 gram mammals eating short grass
(risk ratio = 0.26); therefore, no mitigation is necessary.

For sodium chlorate's non-agricultural uses, the ratios indicate a
potential acute concern to mammals for both spray and granular
formulations, with the highest ratios calculated for small mammals
(ratios =11 and 33 for spray and granular formulations, respectively).
While the ratios presented in Section III suggest that there could be
acute risk to mammals of all sizes that forage in the area where sodium
chlorate is applied to non-agricultural use sites, the risk was likely
over-estimated, since an LD~50~ has not been established. Furthermore,
as previously explained, a reduction in the maximum application rate for
the non-agricultural uses to 392 lbs ai/A would reduce the EEC's of
chlorate in treated areas by approximately 25%. Limitation of the
treatments to spot treatments only would be expected to further reduce
the likelihood that a terrestrial organism will come into contact and
consume all of its diet from that area.

[Mammalian Chronic Risk]{.underline}

For mammals, the Agency typically evaluates the mammalian reproductive
effects for exposures greater than 30 days. The interpretation of the
effects seen in the 2-generation rat reproduction toxicity study, used
to derive the mammalian reproduction toxicity endpoint for sodium
chlorate, is difficult in this respect. While effects were observed at
70 mg/kg-bw and above, the effects are not clearly associated with
reduced reproductive success or survival. The mammalian reproductive
NOAEC is based on the highest dose tested in this study (500 mg/kg-bw),
although no toxic or reproductive effects were observed at this level.
Therefore, the NOAEC could be higher than 500 mg/kg-bw, which would
result in lower mammalian reproduction risk estimates. However, the
Agency calculated risk ratios based on the 500 mg/kg-day NOAEL as a
conservative estimate of risk, as presented in Section III. For the
agricultural uses of sodium chlorate, the chronic mammalian LOC of 1.0
was only slightly exceeded for the smallest weight classes of mammals
for most food items and the largest weight class of mammals feeding on
short grass (RQs range from 2.6 to 0.07). The mitigation measures
previously outlined for sodium chlorate use on cotton (maximum
application rate reduced from 7.5 lbs ai/A to 6 lbs ai/A, with the
limitation of a single application, except in California, where a second
application will be allowed), will further reduced chronic mammalian
risk. Furthermore, based on the lack of observed reproductive effects in
the chronic study and the slight LOC exceedances for agricultural uses,
the Agency does not anticipate a chronic risk of concern to mammals from
these uses.

As with the agricultural uses, mammalian reproduction RQs were not
calculated for sodium chlorate's non-agricultural uses. However, the
higher application rates for the non-agricultural uses, and the
resulting higher EECs, suggest that the risk for these uses would be
higher than the risk estimates presented for the agricultural uses. Note
that the mammalian reproduction RQs for the agricultural uses of sodium
chlorate, presented in Section III, are a conservative estimate of risk.
Furthermore, as previously explained, to reduce risk from sodium
chlorate's non-agricultural uses, the maximum application rate will be
reduced to 0.9 lb ai/100 ft^2^. This mitigation measure will reduce the
EECs by approximately 25%. In addition, the limitation to spot
treatments will reduce the likelihood that mammals will come into
contact and consume all of its diet from a treated area. See the
*Analysis of proposed changes to sodium chlorate's application rates and
maximum treated area on potential ecological risks presented in EFED's
reregistration eligibility decision (RED) document*, dated June 13,
2006, for further detail.

2.  **Non-Target Insects**

EPA currently does not estimate RQs for terrestrial non-target insects.
In addition, the Agency has no toxicity data for sodium chlorate.
Therefore, EPA will require data to address this uncertainty.

**3. Non-Target Terrestrial Plants**

Based on chlorate's non-selective mode of action and lack of adequate
toxicity data, the Agency presumes risk to non-target terrestrial plants
at levels above the Agency's level of concern for all uses. The risks to
plants cannot be quantified at this time due to lack of data; however,
the Agency will require data to address this uncertainty.

**b. Aquatic Organisms**

**1. Fish**

There is no acute risk of concern, from either the agricultural or
non-agricultural uses of sodium chlorate, to freshwater or
estuarine/marine fish. All risk ratios are less than 0.05, which is
below the Agency's acute LOC of 0.5 and below the acute endangered
species LOC of 0.05. However, some data suggest that brown trout
(freshwater fish) could be substantially more sensitive than other fish
species tested to chlorate's toxicity. It is uncertain if these data are
reliable; therefore, the Agency will require additional testing in brown
trout to address this area of uncertainty.

No chronic fish toxicity studies are available to allow for chronic risk
to fish to be quantified. Therefore, the Agency will require data to
address this uncertainty.

**2. Aquatic Invertebrates**

For freshwater invertebrates, acute RQs are below the acute LOC of 0.5
and the endangered species acute LOC of 0.05, for both agricultural and
non-agricultural uses of sodium chlorate. Therefore, acute risk to
freshwater invertebrates is not of concern to the Agency, and no
mitigation is required.

For saltwater invertebrates, the acute risk ratios for sodium chlorate's
agricultural and nonagricultural uses were below the Agency's acute LOC
of 0.5, in addition to the endangered species acute LOC of 0.05 (highest
ratio = 0.04 for non-agricultural uses). Therefore, acute risk to
saltwater invertebrates is not of concern to the Agency.

Chronic risk to invertebrates (freshwater and saltwater) was not
assessed, since treatment-related effects were not observed at any
concentration in available studies.

**3. Aquatic Plants**

For non-endangered aquatic plants, the Agency's LOC of 1.0 was not
exceeded for either the agricultural or nonagricultural uses of sodium
chlorate (highest RQ = 0.91 for non-agricultural uses). Therefore, risk
to non-endangered aquatic plants is not of concern to the Agency.

For endangered aquatic plants, the Agency's LOC of 1.0 was not exceeded
for sodium chlorate's agricultural uses (highest RQ = 0.29), but the LOC
was exceeded for sodium chlorate's non-agricultural uses (highest RQ =
12.6). However, the mitigation measures listed above for the
non-agricultural uses of sodium chlorate, including a reduction in the
application rate and treated area, result in a reduction of the
endangered vascular plant RQ from 12.6 to 1.5. While this is a
significant improvement, it is still above the Agency's endangered plant
LOC of 1.0. Furthermore, because of a lack of submitted data, there is
uncertainty remaining on sodium chlorate's toxicity to aquatic plants.
The Agency will require data to address this area of uncertainty.

[]{#__RefHeading___Toc140567167 .anchor}**3. Summary of Mitigation
Measures**

The following mitigation measures are necessary for sodium chlorate to
be eligible for reregistration. These include use restrictions,
voluntary cancellations and/or use deletions, and personal protective
equipment.

Agricultural use mitigation:

-   Engineering controls (enclosed cockpits) for aerial applications on
    agricultural crops.

-   For cotton, the maximum application rate will be reduced from 7.5
    lbs ai/A to 6 lbs ai/A, and applications will be limited to a single
    applications in all states except California, where a second
    application will be allowed.

Non-agricultural use mitigation:

-   All non-agricultural uses will be limited to spot treatments only
    (with the exception of the granular formulation for use under
    asphalt, although this use will be limited to an 8000 ft^2^
    treatment area). The uses limited to spot treatments include, but
    are not limited to: building perimeters (including farm buildings),
    driveways, parking lots, fence rows, military installations,
    pipelines, railroads, lumberyards, industrial sites (transformers,
    generators, utility poles, etc.), tennis court perimeters, picnic
    areas, bleachers, cemeteries, fuel tanks, airport runways, helo
    pads, wood decks, guard rails, highway medians, sidewalks/walkways,
    vacant lots, fire hydrants, recreational areas, and other similar
    areas.

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-   Use on rights-of-way and ditch banks will be cancelled.

-   The label will specify a maximum application rate of 0.9 lb ai/100
    ft^2^.

    []{#__RefHeading___Toc140567168 .anchor}**F. Other Labeling
    Requirements**

To be eligible for reregistration, various use and safety information
will be included in the labeling of all end-use products containing
sodium chlorate. For the specific labeling statements and a list of
outstanding data, refer to Section V of this RED document.

Number range CHAPTER []{#__RefHeading___Toc140567169 .anchor}**1.
Endangered Species Considerations**

The Agency's screening level assessment results in the determination
that sodium chlorate will have no acute risks to birds, no acute risks
to fish (freshwater and estuarine/marine), and no acute or chronic risks
to aquatic invertebrates (freshwater and estuarine/marine).

However, the preliminary risk assessment for endangered species
indicates that RQs exceed endangered species LOCs for chronic risks to
birds (RQs up to 11 for agricultural uses and greater for
non-agricultural uses); acute risks to mammals (RQs up to 33); chronic
risks to mammals (RQs up to 1.2 for agricultural uses and greater for
non-agricultural uses); and risks to aquatic plants (RQs up to 13).
Risks could not be calculated for terrestrial plants and for chronic
risks to fish; however, the Agency will be requiring data.

Further, potential indirect effects to any species dependent upon a
species that experiences effects from use of sodium chlorate can not be
precluded based on the screening level ecological risk assessment. These
findings are based solely on EPA's screening level assessment and do not
constitute "may affect" findings under the Endangered Species Act.

The Agency has developed the Endangered Species Protection Program to
identify pesticides whose use may cause adverse impacts on endangered
and threatened species, and to implement mitigation measures that
address these impacts. The Endangered Species Act (ESA) requires federal
agencies to ensure that their actions are not likely to jeopardize
listed species or adversely modify designated critical habitat. To
analyze the potential of registered pesticide uses that may affect any
particular species, EPA uses basic toxicity and exposure data developed
for the REDs and considers it in relation to individual species and
their locations by evaluating important ecological parameters, pesticide
use information, geographic relationship between specific pesticide uses
and species locations, and biological requirements and behavioral
aspects of the particular species, as part of a refined species-specific
analysis. When conducted, this species-specific analysis will take into
consideration any regulatory changes recommended in this RED that are
being implemented at that time.

Following this future species-specific analysis, a determination that
there is a likelihood of potential impact to a listed species or its
critical habitat may result in: limitations on the use of sodium
chlorate, other measures to mitigate any potential impact, or
consultations with the Fish and Wildlife Service or the National Marine
Fisheries Service as necessary. If the Agency determines use of sodium
chlorate "may affect" listed species or their designated critical
habitat, EPA will employ the provisions in the Services regulations (50
CFR Part 402). Until that species-specific analysis is completed, the
risk mitigation measures being implemented through this RED will reduce
the likelihood that endangered and threatened species may be exposed to
sodium chlorate at levels of concern. EPA is not requiring specific
sodium chlorate label language at the present time relative to
threatened and endangered species. If, in the future, specific measures
are necessary for the protection of listed species, the Agency will
implement them through the Endangered Species Protection Program.

[]{#__RefHeading___Toc140567170 .anchor}**2. Spray Drift Management**

The Agency has been working closely with stakeholders to develop
improved approaches for mitigating risks to human health and the
environment from pesticide spray and dust drift. As part of the
reregistration process, EPA will continue to work with all interested
parties on this important issue.

From its assessment of sodium chlorate, as summarized in this document,
the Agency concludes that certain drift mitigation measures are needed
to address the risks from off-target drift for sodium chlorate,
including a requirement for medium to coarse droplet size. Label
statements implementing these measures are listed in the \"spray drift
management\" section of the label table (Table 28 in Section V of this
RED document. In the future, sodium chlorate product labels may need to
be revised to include additional or different drift label statements.

Number range CHAPTER[]{#__RefHeading___Toc140567171 .anchor}**V. What
Registrants Need to Do**

[]{#__RefHeading___Toc140567172 .anchor}**A. Manufacturing-Use
Products**

[]{#__RefHeading___Toc140567173 .anchor}**1. Generic Data Requirements**

The generic data base supporting the reregistration of sodium chlorate
has been reviewed and determined to be substantially complete. However,
there are a few data gaps remaining, and these data, presented in Table
27, must be submitted or the Agency may take regulatory action on
registrations of pesticide products containing sodium chlorate.

[]{.mark}

  --------------------------------------------- ------------ ------------
  **Table 27. Guideline Requirements for Sodium              
  Chlorate**                                                 

  **Data Requirement**                          **Old        **New OPPTS
                                                Guideline    Guideline
                                                Number**     No.**

  Magnitude of the Residue-                     171-4j       860.1480
  Meat/Milk/Poultry/Eggs                                     

  Submittal of Analytical Reference Standards   171-13       860.1650

  28-Day Inhalation Toxicity                    82-4         870.3465

  Terrestrial Field Dissipation or              164-1        835.6100
  Retrospective Monitoring Study                             

  Freshwater Fish Early Life Stage              72-4 (a)     850.1400

  Avian Reproduction (1-Generation, Duck)       71-4b        850.2300

  Seedling Emergence (Tier II only)             123-1 (a)    850.4225

  Vegetative Vigor (Tier II only)               123-1 (b)    850.4250

  Aquatic Plant Toxicity, using *Lemna* spp.    123-2        850.4400
  (Tier II)                                                  

  Honey Bee Acute Contact Toxicity              141-1        850.3020
  --------------------------------------------- ------------ ------------

While the terrestrial field dissipation (835.6100) guideline study may
not be appropriate for sodium chlorate, the Agency is still concerned
about the prolonged use of sodium chlorate on cotton (about 50 years).
Terrestrial field dissipation data are not available for sodium
chlorate, and the guideline requirement for this study was never waived.
There are some reports that sodium chlorate can be persistent in the
field (ranging from 6 months to 5 years, depending on application rate,
soil type, fertility, organic matter, moisture, and weather conditions).
Also, several labels report that sodium chlorate is effective for the
control of weeds for up to a year, which indicates that chlorate may
persist for up to a year. Therefore, the range of persistence of sodium
chlorate in the field remains a major uncertainty in the environmental
fate behavior of this chemical. Use of sodium chlorate in the field
requires that it be applied in conjunction with a fire retardant to
minimize fire incidents. It is unclear how the fire retardant could
influence the persistence in the field. Even though the persistence of
chlorate in the field is uncertain, a terrestrial field dissipation data
from a study conducted as per guideline 835.6100 may not provide
adequate data because of the complexity of the chlorine oxyanion system
and analytical chemistry methodology. Given that chloride is the end
chemical species of chlorate, it poses the question of increased
chloride from year-after-year usage (*i.e*., salinization), and leaching
of chloride to ground water, particularly in areas where chloride is not
a significant, natural component in soil and/or ground water. Therefore,
the Agency recommends a retrospective monitoring study (soil; ground
water) aimed to address the effect of prolong use of sodium chlorate on
cotton. The study must be conducted upon agreement of a protocol, but
monitoring sites in coastal areas should not be included.

[]{#__RefHeading___Toc140567174 .anchor}**2. Labeling for
Manufacturing-Use Products**

To ensure compliance with FIFRA, manufacturing-use product (MUP)
labeling should be revised to comply with all current EPA regulations,
PR Notices, and applicable policies. The MUP labeling should bear the
labeling contained in Table 28.

[]{#__RefHeading___Toc140567175 .anchor}**B. End-Use Products**

[]{#__RefHeading___Toc140567176 .anchor}**1. Additional Product-Specific
Data Requirements**

Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed
product-specific data regarding the pesticide after a determination of
eligibility has been made. The registrant must review previous data
submissions to ensure that they meet current EPA acceptance criteria and
if not, commit to conduct new studies. If a registrant believes that
previously submitted data meet current testing standards, then the study
MRID numbers should be cited according to the instructions in the
Requirement Status and Registrants Response Form provided for each
product. The Agency intends to issue a separate product-specific data
call-in (PDCI) outlining specific data requirements.

[]{#__RefHeading___Toc140567177 .anchor}**2. Labeling for End-Use
Products**

To be eligible for reregistration, labeling changes are necessary to
implement measures outlined in Section IV above. Specific language to
incorporate these changes is provided in Table 28. Generally, conditions
for the distribution and sale of products bearing old labels/labeling
will be established when the label changes are approved. However,
specific existing stocks time frames will be established case-by-case,
depending on the number of products involved, the number of label
changes, and other factors.

[]{#__RefHeading___Toc140567178 .anchor}**C. Labeling Changes Summary
Table**

For sodium chlorate to be eligible for reregistration, all sodium
chlorate labels must be amended to incorporate the risk mitigation
measures outlined in Section IV. Table 28 describes how language on the
labels should be amended.

D.  []{#__RefHeading___Toc140567179 .anchor}**Existing Stocks**

    Registrants may generally distribute and sell products bearing old
    labels/labeling for 18 months after the date of approval of revised
    labels implementing the changes described in this RED. Registrants
    and all other persons remain obligated to meet pre-existing label
    requirements and existing stocks requirements applicable to stocks
    they sell or distribute.

[^1]: Unless they chemisorb to soil or sediment particulates.
    Chemisorption of chlorate is unlikely.

[^2]: The term "redox chemistry" is used as an overall term for
    oxidation and reduction reactions. Other terms that are frequently
    used for oxidizers are "oxidants," "oxidizing agents." Reductants
    are frequently referred to as "reducing agents." All redox reactions
    require an oxidant and a reductant. Reductants are electron donors,
    while oxidants are electron acceptors.