ention, 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

  TOC \o "1-3" \h \z \u    HYPERLINK \l "_Toc187489621"  Inorganic
Chlorates Reregistration Eligibility Decision Team	  PAGEREF
_Toc187489621 \h  v

  HYPERLINK \l "_Toc187489622"  Glossary of Terms and Abbreviations
PAGEREF _Toc187489622 \h  vi

  HYPERLINK \l "_Toc187489623"  Abstract	  PAGEREF _Toc187489623 \h
viii

  HYPERLINK \l "_Toc187489624"  I.	Introduction	  PAGEREF _Toc187489624
\h  1

  HYPERLINK \l "_Toc187489625"  II.	Chemical Overview	  PAGEREF
_Toc187489625 \h  3

  HYPERLINK \l "_Toc187489626"  A.	Regulatory History	  PAGEREF
_Toc187489626 \h  3

  HYPERLINK \l "_Toc187489627"  B.	Chemical Identification – Sodium
Chlorate	  PAGEREF _Toc187489627 \h  3

  HYPERLINK \l "_Toc187489628"  C.	Use Profile	  PAGEREF _Toc187489628
\h  3

  HYPERLINK \l "_Toc187489629"  D.	Estimated Usage of Sodium Chlorate
PAGEREF _Toc187489629 \h  4

  HYPERLINK \l "_Toc187489630"  III.	Summary of Inorganic Chlorates Risk
Assessments	  PAGEREF _Toc187489630 \h  6

  HYPERLINK \l "_Toc187489631"  A.	Human Health Risk Assessment
PAGEREF _Toc187489631 \h  6

  HYPERLINK \l "_Toc187489632"  1.	Toxicity of Sodium Chlorate	  PAGEREF
_Toc187489632 \h  6

  HYPERLINK \l "_Toc187489633"  2.	Carcinogenicity of Sodium Chlorate
PAGEREF _Toc187489633 \h  9

  HYPERLINK \l "_Toc187489634"  3.        Sodium Chlorate Endocrine
Effects	  PAGEREF _Toc187489634 \h  10

  HYPERLINK \l "_Toc187489635"  4.	Metabolites and Degradates	  PAGEREF
_Toc187489635 \h  10

  HYPERLINK \l "_Toc187489636"  5.	Dietary Exposure and Risk (Food)
PAGEREF _Toc187489636 \h  11

  HYPERLINK \l "_Toc187489637"  6.	Dietary Exposure and Risks (Drinking
Water)	  PAGEREF _Toc187489637 \h  13

  HYPERLINK \l "_Toc187489638"  7.	Residential Exposure and Risk
PAGEREF _Toc187489638 \h  17

  HYPERLINK \l "_Toc187489639"  8.	Aggregate Risk	  PAGEREF
_Toc187489639 \h  20

  HYPERLINK \l "_Toc187489640"  9.	 Occupational Exposure and Risk
PAGEREF _Toc187489640 \h  21

  HYPERLINK \l "_Toc187489641"  B.	Environmental Fate and Effects Risk
Assessment	  PAGEREF _Toc187489641 \h  27

  HYPERLINK \l "_Toc187489642"  1.	Environmental Fate and Transport
PAGEREF _Toc187489642 \h  27

  HYPERLINK \l "_Toc187489643"  2.	Ecological Exposure and Risk
PAGEREF _Toc187489643 \h  28

  HYPERLINK \l "_Toc187489644"  IV.	Risk Management, Reregistration, and
Tolerance Reassessment	  PAGEREF _Toc187489644 \h  40

  HYPERLINK \l "_Toc187489645"  A.	Determination of Reregistration
Eligibility	  PAGEREF _Toc187489645 \h  40

  HYPERLINK \l "_Toc187489646"  B.	Public Comments and Responses
PAGEREF _Toc187489646 \h  40

  HYPERLINK \l "_Toc187489647"  C.	Regulatory Position	  PAGEREF
_Toc187489647 \h  41

  HYPERLINK \l "_Toc187489648"  1.	Food Quality Protection Act Findings
 PAGEREF _Toc187489648 \h  41

  HYPERLINK \l "_Toc187489649"  2.	Endocrine Disruptor Effects	  PAGEREF
_Toc187489649 \h  42

  HYPERLINK \l "_Toc187489650"  3.	Cumulative Risks	  PAGEREF
_Toc187489650 \h  42

  HYPERLINK \l "_Toc187489651"  4.	Endangered Species	  PAGEREF
_Toc187489651 \h  43

  HYPERLINK \l "_Toc187489652"  D.         Tolerance Reassessment
Summary	  PAGEREF _Toc187489652 \h  44

  HYPERLINK \l "_Toc187489653"  E.	Regulatory Rationale	  PAGEREF
_Toc187489653 \h  46

  HYPERLINK \l "_Toc187489654"  1.	Human Health Risk Management
PAGEREF _Toc187489654 \h  46

  HYPERLINK \l "_Toc187489655"  2.	Non-Target Organism (Ecological) Risk
Management	  PAGEREF _Toc187489655 \h  52

  HYPERLINK \l "_Toc187489656"  3.	 Summary of Mitigation Measures
PAGEREF _Toc187489656 \h  57

  HYPERLINK \l "_Toc187489657"  F.	Other Labeling Requirements	  PAGEREF
_Toc187489657 \h  58

  HYPERLINK \l "_Toc187489658"  1.	 Endangered Species Considerations
PAGEREF _Toc187489658 \h  58

  HYPERLINK \l "_Toc187489659"  2.	Spray Drift Management	  PAGEREF
_Toc187489659 \h  59

  HYPERLINK \l "_Toc187489660"  V.	What Registrants Need to Do	  PAGEREF
_Toc187489660 \h  60

  HYPERLINK \l "_Toc187489661"  A.	Manufacturing-Use Products	  PAGEREF
_Toc187489661 \h  60

  HYPERLINK \l "_Toc187489662"  1.	Generic Data Requirements	  PAGEREF
_Toc187489662 \h  60

  HYPERLINK \l "_Toc187489663"  2.	Labeling for Manufacturing-Use
Products	  PAGEREF _Toc187489663 \h  61

  HYPERLINK \l "_Toc187489664"  B.	End-Use Products	  PAGEREF
_Toc187489664 \h  61

  HYPERLINK \l "_Toc187489665"  1.	Additional Product-Specific Data
Requirements	  PAGEREF _Toc187489665 \h  61

  HYPERLINK \l "_Toc187489666"  2.	Labeling for End-Use Products
PAGEREF _Toc187489666 \h  61

  HYPERLINK \l "_Toc187489667"  C.	Labeling Changes Summary Table
PAGEREF _Toc187489667 \h  61

  HYPERLINK \l "_Toc187489668"  D.	Existing Stocks	  PAGEREF
_Toc187489668 \h  61

  HYPERLINK \l "_Toc187489669"  Summary of Labeling Changes for Sodium
Chlorate	  PAGEREF _Toc187489669 \h  63

  HYPERLINK \l "_Toc187489670"  Appendix A.  Use Patterns Eligible for
Reregistration for Sodium Chlorate	  PAGEREF _Toc187489670 \h  71

  HYPERLINK \l "_Toc187489671"  Appendix B.  Generic Data Requirements
and Studies Used in Reregistration	  PAGEREF _Toc187489671 \h  81

Appendix C.  Bibliography  HYPERLINK \l "_Toc187489672"  	  PAGEREF
_Toc187489672 \h  85

  HYPERLINK \l "_Toc187489673"  Appendix D:  Technical Support Documents
94

  HYPERLINK \l "_Toc187489674"  Appendix E:  List of Available Related
Documents and Electronically Available Forms	95

 Inorganic Chlorates Reregistration Eligibility Decision Team

Biological and Economic Analysis Assessment

Rafael Prieto

Alan Halvorson

Nicole Zinn

Andrew Lee

Environmental Fate and Effects Risk Assessment

Brian Anderson

Silvia Termes

Jim Goodyear

Stephanie Syslo

Health Effects Risk Assessment

Susan Hummel

Bonnie Cropp-Kohlligian

Abdullah Khasawinah

Matthew Crowley

Thurston Morton

Gary Otakie

Registration Support

	Juanita Gilchrist

	Jim Tompkins

Risk Management

Molly Clayton

Kimberly Nesci

Office of General Counsel

	Erin Koch

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

LC50		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

LD50		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

Abstract tc "EXECUTIVE SUMMARY"

	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.

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/.

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.

	A.	Regulatory History

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.

	B.	Chemical Identification – Sodium Chlorate

Chemical Structure:

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

Chemical Name:		Sodium chlorate

Trade Names:			  SEQ CHAPTER \h \r 1 Ferti-Lome, Barespot, Tri-Kil,
Bareground, Prometon, Pramitol,

Killsall, TriChlor

Chemical Family:		Inorganic salt

Case Number:			4049

CAS Number:			  SEQ CHAPTER \h \r 1 7775-09-9

PC Code:			073301

Molecular Weight:		106.5

Empirical Formula:		  SEQ CHAPTER \h \r 1 NaClO3

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

Nexen Chemical USA, Moore Agricultural Products Company, Inc.

	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

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.

	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.

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   HYPERLINK
"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.

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.

		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

Guideline Number	Study Type	MRID No.	Results	Toxicity Categorya

870.1100	Acute oral -Rats	41819901	LD50 (5000 mg/kg (rat)	IV

870.1200	Acute dermal - Rabbits	42497601	LD50 = > 2000 mg/kg	III

870.1300	Acute inhalation - Rats	41819903	LC50 = 5.59 mg/L	IV

870.2400	Acute eye irritation - Rabbit	00085090  00102998

41819904	mildly irritating	III

870.2500	Acute dermal irritation - Rabbit	42497602	minimally irritating
III

870.2600	Skin sensitization - guinea pigs	41819906	not a dermal
sensitizer	NA

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, t
SEQ CHAPTER \h \r 1 he 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.

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 Toxicological Doses and Endpoints for Chlorate per
se for Use in Human Risk Assessments for Inorganic Chlorates

Exposure Scenario	Dose, Uncertainty Factors	FQPA Safety Factor and Level
of Concern	Study and Endpoint for Risk Assessment

Acute Dietary

	Acute RfD= not applicable	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.

Chronic Dietary

(all populations)

BMDL1 = 0.9 mg/kg/day

UF = 30 (3x interspecies and 10x intraspecies)

Chronic RfD = 0.03 mg/kg/day	FQPA SF = 1X

cPAD = Chronic RfD

                FQPA SF

cPAD= 0.03 mg/kg/day

Chronic Study in rats (NTP, 2004).

The LOAEL= 5 mg/kg/day based on increased thyroid gland follicular cell
hypertrophy and follicular cell mineralization.

Short- and Intermediate-Term Incidental Oral

Oral NOAEL =30 mg/kg/day

UF = 100	FQPA SF = 1X

Residential LOC for MOE =100

Subchronic study in rats McCauley et al, 1995.  Pituitary effects
(vacuolization) and thyroid gland effects (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-, Intermediate-, and Long-Term Dermal

Not applicable	Dermal absorption is unlikely due to the ionic nature and
water solubility of sodium chlorate

Short-, Intermediate-, and Long-Term Inhalation

NOAEL =30 mg/kg/day2

UF = 100	FQPA SF = 1X

Residential LOC for MOE =100

Occupational LOC for MOE =100

McCauley et al, 1995

Cancer (Oral, dermal, inhalation)

Classification:  Not likely to be carcinogenic to humans at doses that
do not alter thyroid hormone homeostasis.

UF = uncertainty factor, FQPA SF = FQPA safety factor, NOAEL = no
observed adverse effect level, LOAEL = lowest observed adverse effect
level, PAD = population adjusted dose (a = acute, c = chronic), RfD =
reference dose, MOE = margin of exposure, LOC = level of concern, NA =
Not Applicable

1.  A NOAEL was not identified in this study.  Therefore a bench mark
dose (BMD) analysis was performed and a BMDL of 28 mg sodium chlorate/L
(22 mg chlorate/L) was calculated.  This corresponds to 0.9 mg
chlorate/kg/day oral dose.

2.  A 100% inhalation absorption factor is used for extrapolating from
an oral endpoint of toxicity.

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 a  SEQ CHAPTER \h \r 1  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.

	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.

		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 (ClO3-), chlorite (ClO2-), and chloride (Cl-).  Based on
published rat metabolism data, terminal residues of sodium chlorate in
animal tissues are also expected to be chlorate (ClO3-), chlorite
(ClO2-), 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 (ClO2-, 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.)

5.	Dietary Exposure and Risk (Food)

  SEQ CHAPTER \h \r 1 	  SEQ CHAPTER \h \r 1 Dietary exposure (food
only) to inorganic chlorates as the chlorate ion (ClO3-) 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 (ClO3-) 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.    SEQ CHAPTER \h \r 1

a.	Exposure Assumptions

osure 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.    SEQ CHAPTER \h \r 1 No 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.	  SEQ CHAPTER \h \r 1 Chronic 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 Subgroup	cPAD (mg/kg/day)	Exposure (mg/kg/day)	% cPAD

All populations	0.03	0.002730	9

All infants (< 1 year old)

0.004511	15

Children 1-2 years old

0.008376	28

Children 3-5 years old

0.006906	23

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.

6.	Dietary Exposure and Risks (Drinking Water)

Drinking water exposure to pesticides can occur through surface and
groundwater contamination.    SEQ CHAPTER \h \r 1 Chronic 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

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 (ClO3-) 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 (ClO2-) 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

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.

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   SEQ CHAPTER \h \r 1
Chlorate Concentrations - ICR Data

	Hypochlorite

Plantsa	Chlorine Dioxide

Plants b	Combined Hypochlorite and Chlorine Dioxide Plants

Number of Public Water Systems	44	22	66

Number of Water Treatment Plants 	61	29	90

Chlorate Concentration ((g/L)

10th Percentile	23	  52 	24

20th Percentile	37	79	53

50th Percentile (Median)	99	129	108

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.	  SEQ CHAPTER \h \r 1 Chronic 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 90th 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 Subgroup

cPAD

mg/kg/day

% cPAD

Water Estimated at the

Highest Annual Average

(0.69 mg/L)

Water Estimated at the

90th Percentile Annual Average

(0.24 mg/L)

Water

Estimated at the Median Annual Average

(0.11 mg/L)

General U.S. Population

0.03

49

17

8

All Infants (< 1 yr)

159

55

25

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

                        7.	Residential Exposure and Risk

		  SEQ CHAPTER \h \r 1 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 Estimates1

Exposure Scenario (Scenario #)

Daily Area Treated

Crop/Target

Application Rate

Inhalation MOE2

Mixing/loading/applying liquids with a low pressure hand wand sprayer

1000  ft2/day

Spot/edging treatment

23.7

 lb/Ai/1000 ft2

3000

Loading/applying RTU liquid with a trigger pump sprayer

1  gallon/day

Spot/edging treatment

0.196

lb/Ai/gallon

87000

Mixing/loading/applying liquids with a sprinkler can

1000 ft2/day

Spot/edging treatment

23.7

lb/Ai/1000 ft2

5200

Applying liquid with a RTU sprinkler can

1 gallon /day

Spot/edging treatment

0.27

lb/Ai/gallon

710000

Applying granules by hand

1000 ft2/day

Spot/edging treatment

12

lb/Ai/1000 ft2

370

Loading and applying granules with a belly grinder

1000 ft2/day

Spot/edging treatment

12

lb/Ai/1000 ft2

2800

Loading and applying granules with a push-type spreader

1000 ft2/day

Spot/edging treatment

12

lb/Ai/1000 ft2

200000

   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 Subgroup

Scenario

Route

MOE

Combined MOE

               Child

Hand-to-Mouth

Oral

29000

23000

Object-to-Mouth

Oral

110000

Soil Ingestion

Oral

8600000

8.	  SEQ CHAPTER \h \r 1 Aggregate 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.  Short-Term Aggregate Risk Calculations

Population

Target Aggregate MOE

MOE

Food + water

MOE inhalation

Aggregate MOE

(food + water + residential)

    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 90th 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 Subgroupa	cPAD

(mg/kg/day)	% cPAD (food + drinking water)

Highest Annual Average

(0.69 mg/L)	90th Percentile Annual Average

(0.24 mg/L)	Median Annual Average

(0.11 mg/L)

General US Population	0.03	58	26	17

All Infants (< 1 yr)

174	70	40

Children 1-2 yrs

100	53	39

Children 3-5 yrs

90	47	34

				  tc "7.3	Cancer Dietary Risk - Food + Water  " \l 2 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. tc "a.	Toxicity " \l 4

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:

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);

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

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);

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

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 (>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 Intermediate-Term Occupational
Inhalation Exposure

Exposure Scenario 	Daily Area Treated1	Crop/Target	Application Rate

(lb/Ai/A)	Baseline

Inhalation MOE2	PPE3	Engineering Controls

Mixer/Loaders

Mixing/Loading liquids for aerial application 	1200	Cotton, Corn, Rice,
Dry Beans, Grain Sorghum, Flax, Safflower, Sunflower, Soybeans	7.5	190
-------	--------

Fallow Land, Wheat	6	240	-------	--------

	350	Chili Peppers (for processing only), Potatoes	12.5	400	-------
--------

Ornamental Gourds, Cucurbits (grown for seed)	6	830	-------	--------

Guar Beans, Southern Peas	7.5	670	-------	--------

Mixing/Loading liquids for groundboom application 	200	Cotton, Corn,
Rice, Dry Beans, Grain Sorghum, Flax, Safflower, Sunflower, Soybeans	7.5
1200	-------	--------

Fallow Land, Wheat	6	1500	-------	--------

	80	Chili Peppers (for processing only), Potatoes	12.5	1800	-------
--------

Ornamental Gourds, Cucurbits (grown for seed)	6	3600	-------	--------

Guar Beans, Southern Peas 	7.5	2900	-------	--------

	40	Industrial/Non-Crop Sites	1032	42	210	--------

	523	84	420	--------

	132	330	-------	--------

Mixing/Loading liquids for rights-of-way sprayer application 	5
Rights-of-Way & Industrial/Non-Crop Sites	1032	340	-------	--------

	523	670	-------	--------

	132	2700	-------	--------

Loading granules for tractor-drawn spreader application 	40
Industrial/Non-Crop Sites	523	59	300	--------

	240	130	-------	--------

	161	190	-------	--------

Applicators

Aerial spray applications

(enclosed cockpit)	1200	Cotton, Corn, Rice, Dry Beans, Grain Sorghum,
Flax, Safflower, Sunflower, Soybeans	7.50	--------	-------	3400

Fallow Land, Wheat	6	--------	-------	4300

	350	Guar Beans, Southern Peas	7.5	--------	-------	12000

Chili Peppers (for processing only), Potatoes	12.5	--------	-------	7100

Ornamental Gourds, Cucurbits (grown for seed)	6	--------	-------	15000

Groundboom spray applications 	1200	Cotton, Corn, Rice, Dry Beans, Grain
Sorghum, Flax, Safflower, Sunflower, Soybeans	7.5	1900	-------	--------

Fallow Land, Wheat	6	2400	-------	--------

	350	Guar Beans, Southern Peas	7.5	4700	-------	--------

Chili Peppers (for processing only), Potatoes	12.5	2800	-------	--------

Ornamental Gourds, Cucurbits (grown for seed)	6	5900	-------	--------

	40	Industrial/Non-Crop Sites	1032	69	340	1200 (closed cab)

	523	140	-------	2300 (closed cab)

132	540	-------	9200 (closed cab)

Rights-of-way sprayer applications 	5	Rights-of-Way &
Industrial/Non-Crop Sites	1032	110	-------	--------

	523	210	-------	--------

	132	820	-------	--------

Tractor-drawn spreader applications	40	Industrial/Non-Crop Sites	523	84
420	460 (closed cab)

	240	180	-------	990 (closed cab)

	161	270	-------	1500 (closed cab)

Flaggers

Flagging for aerial spray applications	350	Various Agricultural Crops
12.5	1400	-------	--------

Mixer/Loader/Applicators & Loader/Applicators

M/L/A liquids with a low pressure handwand sprayer 	2
Industrial/Non-Crop Sites	1032	34	170	--------

	523	67	330	--------

	132	270	-------	--------

M/L/A liquids with a handgun sprayer 	5	Industrial/Non-Crop Sites	1032
230	-------	--------

	523	450	-------	--------

	132	1800	-------	--------

L/A granules with a belly grinder 	1	Industrial/Non-Crop Sites	523	65
320	--------

	240	140	-------	--------

	161	210	-------	--------

L/A granules with a push-type spreader	5	Industrial/Non-Crop Sites	523
110	-------	--------

	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.

      Incident  tc "Incident " \l 2  Reports

	  SEQ CHAPTER \h \r 1    SEQ CHAPTER \h \r 1 Available 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 15th 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.

	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.

		1.	Environmental Fate and Transport  tc "		1.	Environmental Fate and
Transport " \l 3

	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 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 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.

		2.	Ecological Exposure and Risk

	  SEQ CHAPTER \h \r 1 To 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…	LOC

terrestrial animals	LOC

aquatic animals	LOC

plants

Acute Risk …there is potential for acute risk; regulatory action may
be warranted in addition to restricted use classification	0.5	0.5	1.0

Acute Endangered Species …endangered species may be adversely affected
0.1	0.05	1.0

Chronic Risk …there is potential for chronic risk	1	1	NA

a.	Terrestrial Organisms

Birds and Mammals

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 labeled application rate	No. of applications	Application
interval

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

Cotton	7.5 lbs ai/A	2	30 days

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

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

	The predicted upper 90th 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 90th Percentile Residue Levels	Predicted Mean Residue
Levels

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

Agricultural Uses (Spray Applications)

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

Cotton	2800	1300	1600	170	990	420	520	81

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

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

Non-Agricultural Uses (Spray Applications)

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

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

		For granular applications, estimation of chlorate loading per unit
area (mg/ft2) 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	Application Rate

(lbs ai/A)	EEC (mg/ft2)a

Parking lots, under asphalt paving, fence lines, building perimeters,
ditch banks, picnic areas, vacant lots, wood decks, bleachers,
cemeteries, fuel tanks, runways, helo pads, etc.	520	5400

Around buildings, storage areas, fences, pumps, machinery, fuel tanks,
recreational areas, roadways, guard rails, airports, rights of ways.	160
1700

   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.  tc "Table 37.  Toxicity reference values for mammals and
birds for permethrin. " \f D

Exposure Scenario	Species	Toxicity Value Used in Risk Assessment	Effect

Mammals

Acute	Rat	LD50 = > 5000 mg/kg-bw	At 5000 mg/kg-bw, 1/10 animals died.

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

Birds

Acute	Mallard duck	LD50 > 2510 mg/kg-bw	No mortality and no clinical
signs of toxicity were observed.

Chronic	Bobwhite quail	NOAEC = 271 ppm	The LOAEC was 964 ppm based on
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 90th
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 90th percentile
residue levels shown below.

  Table 16.   Avian Chronic Risk Quotients for Sodium Chlorate
Agricultural Uses

Crops	Short grass	Tall grass	Broadleaf forage, small insects	Fruit,
pods, seeds, small insects

Chili peppers; white/Irish potatoes	11.0	5.2	6.3	0.7

Cotton	10.0	4.8	5.9	0.63

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

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

		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  tc "

Acute  " \l 4 RQs were not calculated for mammals.  The LD50 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 LD50 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 LD50s 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 90th percentile EEC (mg/kg-bw) for the range of maximum
application rates for all agricultural uses

Food item	Size of mammal

(grams)	Adjusted lowest observed toxic dose (mg/kg-bw)	Range of EECs

(mg/kg-bw)a	Ratio of lowest observed toxic dose to the upper 90th
percentile EEC (unitless)

Short grass	15	10,989	1400 - 2900	0.13 - 0.26

	35	8891	950 - 2000	0.11 - 0.22

	1000	3846	200 - 450	0.052 - 0.12

Tall grass	15	10,989	630 - 1300	0.057 - 0.12

	35	8891	440 - 910	0.049 - 0.10

	1000	3846	99 - 210	0.026 - 0.055

Broadleaf plants/small insects	15	10,989	770 - 1600	0.070 - 0.15

	35	8891	540 - 1100	0.061 - 0.12

	1000	3846	120 - 250	0.031 - 0.065

Fruits, pods, large insects	15	10989	86 - 180	<0.01 - 0.016

	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 LD50 has not been established.  The highest dose tested in the
available toxicity studies (5000 mg/kg-bw) induced 10% mortality.  The
proximity of the LD50 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.  Proximity of the lowest observed acute toxic dose in mammals
to the predicted EEC (mg/kg-bw) for the range of maximum application
rates for all non-agricultural uses (spray applications)

Food item	Size of mammal

(grams)	Adjusted lowest observed toxic dose

(mg/kg-bw)	Range of EECs

(mg/kg-bw)a	Ratio of lowest observed toxic dose to the upper 90th
percentile EEC (unitless)

Short grass	15	10989	11,900 - 119,000	1.1 - 11

	35	8891	8200 - 82,000	0.93 - 9.3

	1000	3846	1900 - 19,000	0.49 - 4.9

Tall grass	15	10989	5400 - 54,000	0.49 - 4.9

	35	8891	3800 - 38,000	0.43 - 4.3

	1000	3846	860 - 8600	0.22 - 2.2

Broadleaf plants/small insects	15	10989	6700 - 67,000	0.61 - 6.1

	35	8891	4600 - 46,000	0.52 - 5.2

	1000	3846	1100 - 11,000	0.27 - 2.7

Fruits, pods, large insects	15	10989	740 - 7400	0.07 - 0.7

	35	8891	520 - 5200	0.06 - 0.6

	1000	3846	120 - 1200	0.03 - 0.3

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/ft2).
 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.

Table 19.  Range of ratios of chlorate’s body weight adjusted LD50 to
granular EECs (mg/ft2) for sodium chlorate’s non-agricultural uses
(granular formulations)

Use	Body Weight (g)	Rat LD50

mg/kg-bw	EEC (mg/ft2)a	Ratio of LD50  to EEC

Parking lots, under asphalt paving, fence lines, building perimeters,
ditch banks, picnic areas, vacant lots, wood decks, bleachers,
cemeteries, fuel tanks, runways, helo pads, etc.

	15	10,989	5400	33

	35	8891	5400	17

	1000	3846	5400	1.4

Around buildings, storage areas, fences, pumps, machinery, fuel tanks,
recreational areas, roadways, guard rails, airports, rights of ways.

	15	10,989	1700	10

	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 Item	15-gram mammal	35-gram mammal	1000-gram mammal

Single application of 12.5 lbs ai/A

Chili peppers; white/Irish potatoes

Chili peppers; white/Irish potatoes	Short Grass	2.6	2.2	1.2

	Tall Grass	1.2	1.0	0.55

	Broadleaf plants/small insects	1.5	1.3	0.67

	Fruits/pods/large insects	0.16	0.14	0.07

Multiple applications (7.5 lbs ai/A, 2 applications, 30-day interval)

Cotton	Short Grass	2.4	2.1	1.1

	Tall Grass	1.1	0.95	0.51

	Broadleaf plants/small insects	1.4	1.2	0.62

	Fruits/pods/large insects	0.15	0.13	 0.07

Single application (7.5 lbs ai/A)a

Corn; flax, guar; southern 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 	Short Grass	1.6	1.3	0.72

	Tall Grass	0.72	0.61	0.33

	Broadleaf plants/small insects	0.88	0.75	0.40

	Fruits/pods/large insects	0.10	0.08	0.04

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 LC50 to the highest concentration tested (1000
mg/L) could not be estimated.  Although 1000 mg/L is not an LC50, 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 EC50 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 Rate Range	Maximum EEC	EC50	RQ

Agricultural uses	4.5–7.5 lb/Ai/A	0.91 mg/L	920 mg/L	<0.01

Non-agricultural uses	132–520 lb/Ai/A	39 mg/L	920 mg/L	<0.042

For saltwater invertebrates, acute RQs were not calculated, because the
proximity of the LC50 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 (EC50) 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 EC50 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.

 to0.9 mg/L	133 mg/L	43 mg/L	<0.01	0.02

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

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 Peak EEC	Algal EC50	Duckweed EC50	Algal RQ	Duckweed RQ

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

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

			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

IV.	Risk Management, Reregistration, and Tolerance Reassessment

	A.	Determination of Reregistration Eligibility

  SEQ CHAPTER \h \r 1 	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.

	B.	Public Comments and Responses  tc "	B.	Public Comments and Responses
" \l 2

	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.

	C.	Regulatory Position

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

  SEQ CHAPTER \h \r 1 	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

  SEQ CHAPTER \h \r 1

	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.

		2.	Endocrine Disruptor Effects

  SEQ CHAPTER \h \r 1

	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.

		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/.

		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