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Potassium Hypochlorite Registration Review Team

Human Health 

Jonathan Leshin

Timothy Dole 

Environmental Fate and Effects

David Bays

Srinivas Gowda

Najm Shamim

Risk Management

Donna Kamarei

James Parker 

Office of General Counsel

Philip Ross
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TERMS, ABBREVIATIONS AND SYMBOLS

AD Antimicrobials Division

A.I. or a.i. active ingredient

aPAD acute population adjusted dose 

ASRI activated sludge respiration inhibition

atm-m3/mole atmospheric pressure-cubic meter per mole

BCF bioconcentration factor 

°C degrees Celsius

CaSO4 calcium sulfate

CaSO3 calcium sulfite

CAS Chemical Abstracts Service 

CCA chromated copper arsenate

CFR Code of Federal Regulations 

CHO Chinese hamster ovary

CMA Chemical Manufacturers Association

CO2 carbon dioxide

COC concentration-of-concern

cPAD chronic population adjusted dose 

CS2 carbon disulfide

DCI data call-in

EC50 median (or 50 percent) effect concentration

EC05 5 percent effect concentration

ECOTOX ECOTOXicology

EDI estimated daily intake

EDSP Endocrine Disruptor Screening Program 

E-FAST Exposure and Fate Assessment Screening Tool

EPI Suite Estimation Program Interface Suite

EPA Environmental Protection Agency 

FDA Food and Drug Administration 

FFDCA Federal Food, Drug, and Cosmetic Act

FGD flue-gas desulfurization

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

FQPA Food Quality Protection Act 

FWP Final Work Plan

g/mol grams per mole

GLN guideline number

HPV high production volume

IDS Incident Data System 

KDDC potassium dimethyldithiocarbamate

Koc organic carbon normalized soil-water partition coefficient

Kd soil-water partition coefficient

Kow octanol-water partition coefficient

LC50 median (or 50 percent) lethal concentration

LD50 median (or 50 percent) lethal dose

LOAEC lowest-observed-adverse-effect-concentration 

LOEC lowest-observed-effect-concentration

LOAEL lowest-observed-adverse-effect-level

Log Kow logarithm of the octanol-water partition coefficient

μg microgram

ml/g milliliter per gram
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mg/kg milligram per kilogram

mg/kg/day milligram per kilogram per day 

mg/L milligram per liter

mm Hg millimeter of mercury

MOE margin of exposure 

MRID Master Record Identification Number

MRL maximum residue limit 

N/A not applicable 

NaDDC sodium dimethyldithiocarbamate salt

nm nanometers

NOAEC no-observed-adverse-effect-concentration

NOAEL no-observed-adverse-effect-level

OCSPP Office of Chemical Safety and Pollution Prevention

OECD Organization for Economic Co-operation and Development

OPP Office of Pesticide Programs

PAD population adjusted dose

PAI pure active ingredient

PDM Probabilistic Dilution Model

% percent

PC Code Pesticide Chemical Code

PCF pounds per cubic foot

pH power of hydrogen or power of the concentration of the hydrogen ion

PHED Pesticide Handler’s Exposure Data

PIS primary irritation score

pKa power of the acid dissociation constant or negative base-10 logarithm of the acid 

dissociation constant of a solution

ppb parts per billion 

ppm parts per million

PWP Preliminary Work Plan

QSAR quantitative structure-activity relationship

RED Reregistration Eligibility Decision

SAR structure activity relationship

SF safety factor

SSTS Section Seven Tracking System

SO2 sulfur dioxide

TEP typical end-use product

TGAI technical grade active ingredient

TMDL total maximum daily loads

UF uncertainty factor

UV/VIS ultraviolet/visible light absorption

% w/w percent weight per weight.

WP wettable powder

WWTPs wastewater treatment plants
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Table of Contents

1 Introduction............................................................................................................................. 7

1.1 Statutory and Regulatory Authority ................................................................................. 7

1.2 Updates to the Workplan.................................................................................................. 9

1.3 Case Overview ................................................................................................................. 9

1.4 Chemical Identification and Properties............................................................................ 9

1.5 Use/Usage Description................................................................................................... 10

1.5.1 Registrations ........................................................................................................... 10

1.5.2 Summary of Registered Uses.................................................................................. 10

1.6 Regulatory History ......................................................................................................... 12

1.6.1 Tolerance Information ............................................................................................ 12

1.7 Incidents......................................................................................................................... 13

1.7.1 Human Health ......................................................................................................... 13

1.7.2 Ecological ............................................................................................................... 13

2 Anticipated Data Needs ........................................................................................................ 13

3 Human Health Risk Assessment........................................................................................... 13

3.1 Existing Toxicological Endpoints.................................................................................. 13

3.2 Dietary Exposure............................................................................................................ 14

3.3 Occupational and Residential Exposures....................................................................... 14

3.4 Aggregate and Cumulative Exposure............................................................................. 14

3.4.1 Aggregate Exposures.............................................................................................. 14

3.4.2 Cumulative Exposures............................................................................................ 14

4 Environmental Risk Assessment........................................................................................... 14

4.1 Environmental Fate Assessment .................................................................................... 15

4.1.1 Leaching [Wood/Paint/Antifoulant Paint/Plastic/Textiles/e.g., treated article]...... 15

4.1.2 Water and Sediment................................................................................................ 15

4.1.3 Soil .......................................................................................................................... 15

4.1.4 Air........................................................................................................................... 15

4.1.5 Other media............................................................................................................. 15

4.1.6 Waste Water Treatment Plants (WWTP)................................................................ 16

4.1.7 Water Quality.......................................................................................................... 16

4.2 Ecological Effects Assessment....................................................................................... 16

4.2.1 Mode of Action....................................................................................................... 16

4.2.2 Measures of Effect (Ecotoxicology Assessment Endpoints).................................. 16

4.3 Exposure Analysis Plan.................................................................................................. 17

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates ............................................ 17

4.4 Effects Analysis Plan ..................................................................................................... 17

5 Endocrine Disruptor Screening Program (EDSP)................................................................. 17

6 Next Steps............................................................................................................................. 18

7 References............................................................................................................................. 20

Appendix A Toxicology Profile............................................................................................... 21

Appendix B Environmental Fate and Transport of Potassium Hypochlorite .......................... 22

Appendix C Ecotoxicology Profile.......................................................................................... 23

Appendix D Product Chemistry............................................................................................... 27
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List of Tables

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: Potassium Hypochlorite 8

Table 2 – Anticipated Registration Review Schedule .................................................................... 8

Table 3 – Chemical Identification of Potassium Hypochlorite....................................................... 9

Table 4 – Physical- Chemical and Environmental Fate Properties for Potassium Hypochlorite . 10

Table 5 – Summary of Potassium Hypochlorite Registered Uses................................................ 10

Table 6 – Acute Toxicity Studies for Potassium Hypochlorite .................................................... 21

List of Figures

None. 
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1 Introduction

This document is the United States Environmental Protection Agency’s (USEPA, EPA or “the 

agency”) Final Work Plan (FWP) for potassium hypochlorite (case 5076). The FWP document 

explains what EPA's Office of Pesticide Programs (OPP) knows about potassium hypochlorite, 

highlighting anticipated data and assessment needs, identifying the types of information that 

would be especially useful to the agency in conducting the review, and providing an anticipated 

timeline for completing potassium hypochlorite’s review.

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The agency intends, by sharing this information in the 

docket, to inform the public of what it knows about potassium hypochlorite and what types of 

new data or other information would be helpful for the agency to receive as it moves toward a 

decision on potassium hypochlorite. As explained further in this document, in the future, if 

appropriate the agency will evaluate this chemical with sodium and calcium hypochlorite (case 

0029). 

1.1 Statutory and Regulatory Authority

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

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

based on scientific data showing that they will not cause unreasonable risks to human health or 

the environment when used as directed on product labeling. The registration review program is 

intended to make sure that, as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no unreasonable 

adverse effects to human health or the environment. Changes in science, public policy, and 

pesticide use practices will occur over time. Through the registration review program, the agency 

periodically reevaluates pesticides to make sure that as change occurs, products in the 

marketplace can be used safely. Information on this program is provided at 

http://www.epa.gov/oppsrrd1/registration_review/.

The agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The agency 

will consider benefits information and data as required by FIFRA. The public phase of 

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

agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. Further, 

the agency believes that potassium hypochlorite is similar to and can be considered with the 

chemicals in case 0029, sodium and calcium hypochlorite. The docket for the sodium and 

calcium hypochlorite case opened in March 2012. No risk assessments are considered necessary 

for any of the three compounds since EPA has concluded that the currently registered uses of the 

hypochlorites will not result in unreasonable adverse effects to the environment. Since no risk 

assessments are necessary, after the final workplan for potassium hypochlorite is issued, the 

agency intends to issue a combined proposed decision for all three compounds. 
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The potassium hypochlorite Preliminary Work Plan (PWP) was published on March 26, 2014 

and the 60-day comment period ended on May 27, 2014. The agency did not receive any 

submissions during the public comment period on the initial docket. 

Documents associated with this registration review can be viewed at http://www.regulations.gov

in docket EPA-HQ-OPP-2014-0157. 

Tables 1 and 2 below summarize the issues relevant to this registration review case and the 

anticipated registration review schedule.

Table 1 – Summary of Anticipated Risk Assessments and Data Needs: Potassium 

Hypochlorite 

Risk Assessment 

Assessment 

Necessary to 

Support 

Registration 

Review

Date of Most 

Recent 

Assessment

Type of Assessment 

Required 

(New/Updated)

Data Anticipated as Needed

Dietary (food) No None None None

Dietary (drinking water) No None None None

Occupational Handler No None None None

Residential Handler No None None None

Residental Post 

Application No None None None

Aggregate No None None None

Cumulative No None None None

Tolerance Review No None None None

Ecological No None None None 

Table 2 – Anticipated Registration Review Schedule

Anticipated Activity Target Date* Completion Date

Phase 1: Opening the Docket 

Open Docket and 60-Day Comment Period for Preliminary Work Plan 2014-03 2014-03-26

Close Public Comment Period 2014-05 2014-05-27

Phase 2: Case Development 

Issue Final Work Plan 2014-09 2014-08

Issue Data Call-In (DCI) N/A

Receive Data to be Considered in Risk Assessment N/A

Open 30-Day Public Comment Period for Preliminary Risk Assessment(s) N/A

Close Public Comment Period N/A 

Phase 3: Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Proposed Decision 2016-09

Close Public Comment Period 2016-11

Issue Final Decision 2017-03

Begin Post-Decision Followup 2017
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Total (years) 3

*The anticipated schedule will be revised as necessary (e.g., need arising under the Endocrine Disruptor Screening Program with 

respect to the active ingredients in this case).

N/A = Not applicable

1.2 Updates to the Workplan

Since the publication of the PWP, the agency has made the following updates: 

 Corrected the timeline in Table 2, the “Anticipated Registration Review Schedule” table.

 Updated section 4.3.1 “Aquatic and Terrestrial Wildlife Exposure Estimates”.

 Deleted the “Guidance for Commenters” section.

 Updated section 6, “Next Steps”.

 Updated Appendix B “Environmental Fate and Transport of Potassium Hypochlorite”. 

Since no public comments were received on the initial docket, no modifications were made to the 

anticipated data needs or registration review schedule in the potassium hypochlorite PWP. This 

document makes final the work plan for the potassium hypochlorite registration review process.

1.3 Case Overview

The docket for the potassium hypochlorite case (case 5076) has been established at 

http://www.regulations.gov in docket number EPA-HQ-OPP-2014-0157.

1.4 Chemical Identification and Properties

Table 3 presents the active ingredient to be assessed in case 5076: potassium hypochlorite (PC 

Code 129053). 

Table 3 – Chemical Identification of Potassium Hypochlorite 

Chemical Name Potassium hypochlorite

Chemical Classification Halogen

PC Code 129053

CAS Number 7778-66-7

Molecular Formula KOCl

Molecular Weight (grams/mole) 90.55

Purity 12.5%

Available chlorine Contains approximately 1.0 lb of Available Chlorine/Gallon

Molecular Structure

The potassium hypochlorite product chemistry information relevant to risk assessment is 

summarized in Table 4 (source: MRIDs KOCl: 47382901, 47445101, and 47594501).
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Table 4 – Physical- Chemical and Environmental Fate Properties for Potassium 

Hypochlorite

Guideline No. Parameter Potassium hypochlorite (12.5%)

Physical/Chemical Properties

830.7000 pH 10.14 - 1% w/w solution in de-ionized water at 21.1-

21.8°C

830.7050 UV/Visible Absorption Does not absorb in uv visible range

830.7200 Melting point Not required

830.7220 Boiling point (oC) Decomposes prior to boiling

830.7300 Density 1.1701 g/ml (9.75 lbs/gal) at 20.1°C

830.7370 Dissociation constant (pKa) Potassium hypochlorite dissociates completely on 

dissolving in water.

830.7550 Octanol-water partition coefficient at 25 °C 

(Log Kow)

NA

830.7840 Solubility in water (mg/L) Complete

830.7950 Vapor pressure (mmHg) NA

atm-m3/mol = atmosphere cubic meter per mole; oC = degrees Celsius; mg/L = milligrams per liter; mmHg = 

millimeters of mercury.

1.5 Use/Usage Description

1.5.1 Registrations

There is one product (EPA Reg. Number 63838-10) that contains potassium hypochlorite. The

product is a soluble concentrate and it contains 12.5 percent potassium hypochlorite which is 

equivalent to approximately 1.0 lb of available chlorine per gallon. The product was registered 

on March 3, 2011.

1.5.2 Summary of Registered Uses

Table 5 presents a summary of the registered uses of potassium hypochlorite that will be 

assessed in this registration review. 

Table 5 – Summary of Potassium Hypochlorite Registered Uses

Use Treatment 

Type Application Method Product Application Rate

Available 

Chlorine

(ppm)

Agricultural Premises and Equipment

Farm Premises Sanitization Surface and Immersion 14 oz/10 ga 1000 ppm

Irrigation Systems 
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Use Treatment 

Type Application Method Product Application Rate

Available 

Chlorine

(ppm)

Irrigation Systems Bacteria and 

Algae Growth 

Sprinkler, Flood, Furrow, 

Border or Drip Irrigation 5 ppm 

Food Handling/Storage Establishments, Premises and Equipment

Food Egg Sanitization Sanitization Spray 2.5 oz/10 ga 200 ppm

Fresh Fruits and Vegetables 

(with potable water rinse)

Sanitization Submersion or Drench 31 oz/250 ga 100 ppm

Fruit and Vegetable Washing 

(without potable water rinse)

Sanitization Spray 6.2 oz/200 ga 25 ppm

Meat and Poultry Plants 

Processing Water Sanitization Circulate 1.4 oz/200 ga 5 ppm

Non-Porous Food Contact 

Surfaces Sanitization

Rinse, Immerse, Circulate 2.5 oz/10 ga 200 ppm

Spray/Fog 7.5 oz/10 ga 600 ppm

Porous Food Contact 

Surfaces Sanitization

Rinse, Immerse, Circulate 7.5 oz/10 ga 600 ppm

Spray/Fog 7.5 oz/10 ga 600 ppm

Potatoes Sanitization Spray 0.5 oz/2 ga 500 ppm

Poultry chiller water and 

carcass wash water Sanitization Circulate 14.4 oz/200 ga 50 ppm

Commercial, Institutional and Industrial Premises and Equipment

Non-Porous Non-Food 

Contact Surfaces 

Sanitization Rinse, Immerse, Circulate 2.5 oz/10 ga 200 ppm

Spray/Fog 2.5 oz/10 ga 200 ppm

Non-Porous Non-Food 

Contact Surfaces Disinfection Rinse, Immerse 7.5 oz/10 ga 600 ppm

Porous Non-Food Contact 

Surfaces Sanitization Rinse, Immerse 7.5 oz/10 ga 600 ppm

Laundry (Commercial) Sanitization Soak, Wash 2.5 oz/10 ga 200 ppm

Residential and Public Access Premises

Laundry (Household) Sanitization Soak, Wash 2.5 oz/10 ga 200 ppm

Human Drinking Water Systems

Drinking Water Disinfection Injection As needed* 0.6 ppm in system

Public Water Systems

Mains

New Tanks, Basins

Sand Filters

Well Casing 

Equipment

Equipment

Tank Cars

Disinfection

Injection

Open Pour

Open Pour

Open Pour

Open Pour

Spray

Spray

As needed*

25 oz/5 ft3

100 oz/150 ft3

6.2 oz/10 ga

26 oz/5 ft3

6.2 oz/5 ga

6.2 oz/10 ga

50 ppm

500 ppm

Unspecified

500 ppm

500 ppm

1000 ppm

500 ppm

Industrial Processes and Water Systems
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Use Treatment 

Type Application Method Product Application Rate

Available 

Chlorine

(ppm)

Cooling Towers Slug

Maintenance Open Pour 130 oz/10,000 ga14 oz/10,000 ga

10 ppm

1 ppm

Pulp and Paper Process 

Water 

Slug

Maintenance Open Pour 130 oz/10,000 ga14 oz/10,000 ga

10 ppm

1.0 ppm

Sewage and Wastewater Effluent

Filter Beds Open Pour As needed100 oz/20 ft2

0.5 ppm

Unspecified

Swimming Pools and Spas

Swimming Pool Shock

Maintenance Open Pour 130 oz/10,000 ga14 oz/10,000 ga

10

1.0

Spas and Hot Tubs Shock

Maintenance Open Pour 10 oz/500 ga6.5 oz/1000 ga

19

5.0

Aquatic Areas

Fish Hatchery Pond Open Pour 2.5 oz/10 ga 200 ppm

Fish Pond Equipment Open Pour 2.5 oz/10 ga 200 ppm

Fish Ponds Open Pour 130 oz/10,000 ga 10 ppm

Maine Lobster Ponds Open Pour 7,700 oz/10,000 ga 600 ppm

*The application rate is specified in terms of the chlorine residual and the amount of product applied will vary 

depending on the chlorine demand of the system being treated.

1.6 Regulatory History

The first product containing potassium hypochlorite as an active ingredient was registered in 

1998; by 2005 all the registered products were canceled. As of 2011 there was a new registration, 

with a variety of uses as outlined in Table 5. 

A Reregistration Eligibility Decision (RED) was not completed for potassium hypochlorite 

because it was registered after November 1, 1984.

1.6.1 Tolerance Information

An exemption from the requirement of a tolerance is established for residues of potassium 

hypochlorite in or on all commodities [40 CFR § 180.1300].

1

 

1 http://www.ecfr.gov/cgibin/retrieveECFR?gp=1&SID=2035ef80559449db2dfc1f34c286e7ca&ty=HTML&h=L&r=SECTION&n=40y25.0.

1.1.27.4.19.197
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1.7 Incidents

1.7.1 Human Health 

As of January 30, 2013, no human health incidents are listed for potassium hypochlorite in the 

OPP’s Incident Data System (IDS).

1.7.2 Ecological

As of February 5, 2013, no ecological incidents are listed for potassium hypochlorite in OPP’s 

Incident Data System (IDS). 

2 Anticipated Data Needs

The agency does not anticipate needing to call in any data to support this registration review.

3 Human Health Risk Assessment

Based on the toxicity profile and exposure scenarios for potassium hypochlorite, EPA believes 

that risks from chronic and subchronic exposures to this pesticide would be minimal and without 

consequences to human health. The agency believes that any acute corrosive risks will be 

sufficiently mitigated by precautionary labeling requiring protection of eyes and skin while using 

this pesticide.

3.1 Existing Toxicological Endpoints

During the generation of the 2014 registration review preliminary work plan, the agency 

conducted an in-depth review of the similarities between potassium hypochlorite and the existing 

registered active ingredients sodium hypochlorite and calcium hypochlorite. Based upon this 

review, the agency has determined that the data available to support the registrations of these 

active ingredients are also applicable to potassium hypochlorite. See Appendix A for toxicology 

profile. 

No additional generic or product-specific acute, chronic or subchronic toxicological studies are

required for this registration review. All toxicology data will be bridged from studies on sodium 

and calcium hypochlorites based on their chemical similarity.2

Potassium hypochlorite is extremely corrosive and can cause severe damage to eyes and skin, 

and therefore has been classified Toxicity Category I based on these acute effects. The agency 

has determined that these risks are adequately mitigated through the use of the specific 

precautionary and first aid statements that have been proposed on the product labeling. Based on 

its similarity to sodium and calcium hypochlorite, potassium hypochlorite was assigned acute 

 

2 U.S. EPA 2012. Registration Review Final Work Plan: Na & Ca Hypochlorite. Docket Number EPA –HQ-OPP

2012-0004.Available at: http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0004-0006.
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oral and dermal toxicities to category IV and acute inhalational toxicity to category III. This 

chemical is not a dermal sensitizer.2

3.2 Dietary Exposure

There are no toxicological endpoints for potassium hypochlorite; therefore, dietary food and 

drinking water exposures do not need to be assessed for registration review.

3.3 Occupational and Residential Exposures

There are no toxicological endpoints for potassium hypochlorite; therefore, occupational and 

residential exposures do not need to be assessed for registration review.

3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures 

There are no toxicological endpoints for potassium hypochlorite; therefore aggregate exposures 

do not need to be assessed for registration review.

3.4.2 Cumulative Exposures 

There are no toxicological endpoints for potassium hypochlorite; therefore, cumulative 

exposures do not need to be assessed for registration review.

4 Environmental Risk Assessment

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

species determination for potassium hypochlorite. A risk assessment was conducted on sodium 

and calcium hypochlorite salts for the RED in 1991. Since these chemicals are very similar in 

their mode of action, all are hypochlorites and release chlorine as the active ingredient, the 

information from the previous assessment of sodium and calcium hypochlorites will be used for 

potassium hypochlorite. If determined necessary during the registration review process, the 

agency will determine potential acute and chronic risks to aquatic organisms exposed to 

potassium hypochlorite that are transported from treatment sites into the aquatic environment. 

Such sites include pulp and paper mill process water systems. 

The registration review process will allow the agency to determine whether each use of the 

potassium hypochlorite has 'no effect' or 'may affect' federally listed threatened or endangered 

species (listed species) or their designated critical habitats. When an assessment concludes that a 

pesticide’s use 'may affect' a listed species or its designated critical habitat, the agency will 

consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Services (the 

Services), as appropriate.
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4.1 Environmental Fate Assessment

As with the sodium and calcium hypochlorite case, the agency does not anticipate the need for an 

environmental fate assessment for potassium hypochlorite. Potassium hypochlorite uses are

exclusively in aqueous medium, and potassium hypochlorite belongs to the hypochlorite class of 

compounds including lithium, sodium, and calcium hypochlorites. These hypochlorites 

dissociate in water to form hypochlorous acid (HOCl), which acts as the active in disinfecting

and sanitizing scenarios. OCSPP’s test guideline series 835 are not applicable to inorganic 

substances, and thus the traditional fate studies like hydrolysis, photolysis, etc. are not 

appropriate for inorganic molecules like potassium hypochlorite.

3

Hypochlorite (HOCl) oxidizes to chlorite (ClO2

-

), chlorate (ClO3

-

), and perchlorate (ClO4

-

) or 

reduces to chloride (Cl-).

The agency has not conducted any environmental and transport exposure assessment for 

potassium hypochlorite. Potassium chemistry is similar to the same group cations like sodium

and calcium. All salts of these metals are highly water soluble. The agency does not intend to 

conduct a down the drain assessment for potassium hypochlorite as further explained in section 

4.1.6.

4.1.1 Leaching [Wood/Paint/Antifoulant Paint/Plastic/Textiles/e.g., treated 

article]

Potassium hypochlorite is not registered for uses in wood treatment or as an antifoulant for boat 

and ship bottoms, or in paints. It is not embedded into plastics or used in surface treatment of 

textiles.

4.1.2 Water and Sediment

Potassium ions exist in earth’s crust, sediments, soils, clay and the binding is strong. 

Hypochlorite in water and soils speciate into oxidized species (chlorite, chlorate, perchlorate) or 

reduce to chloride, depending on the pHs of the medium.

4

4.1.3 Soil

The chemical behavior of potassium and hypochlorite in soil is the same in other media like 

water, sediment and clays.4

4.1.4 Air

Potassium ions can vaporize along with other species, but deposit back to the soils and dissolve

in water.4

4.1.5 Other media

It is a key element for plants. It is present in the intercellular fluids in mammalian systems. Its 

recommended daily intake is: 3500 mg.

4

 

3 F.A. Cotton & G. Wilkinson (Advanced Inorganic Chemistry, 7th edition; chapter 4 and 5).

4 F.A. Cotton & G. Wilkinson (Advanced Inorganic Chemistry, 7th edition; chapter 4 and 5).
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4.1.6 Waste Water Treatment Plants (WWTP)

A down-the-drain assessment is not required for potassium hypochlorite, which forms 

hypochlorous acid instantly. Hypochlorous acid degrades and is unlikely to reach WWTP. 

Potassium ions are not of concern for WWTP.

4

4.1.7 Water Quality

Potassium hypochlorite is not identified as a cause of impairment for any water bodies listed as 

impaired under section 303(d) of the Clean Water Act, based on information provided at the 

agency’s National Pesticides Cause of Impairment of Waters website (searched February 6,

2014).

5

In addition, no Total Maximum Daily Loads (TMDL) have been developed for

potassium hypochlorite, based on information provided at the agency’s National Pesticide 

TMDL web site (searched February 6, 2014)

6

. Potassium ions are not identified as a cause of 

impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, 

based on information provided at the agency’s National Pesticides Cause of Impairment of 

Waters website (February 6, 2014)

7

. There are 175 TMDL/ impaired water bodies (OW’s list 

303(d)) listed for total residual chlorine (TRC) on a national level recorded between 2000-2007. 

TRC is defined as the “amount of remaining chlorine remaining after contact time and is equal to 

available residual chlorine + free available chlorine.” More information on impaired water 

bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/. 

4.2 Ecological Effects Assessment

4.2.1 Mode of Action

In the aquatic environment, toxic action is largely due to hypochlorous acid formed when 

potassium hypochlorite reacts with water. Adverse effects of hypochlorous acid are due mainly 

to its corrosive action. Acute necrosis may occur. Fish gills-structure may be damaged; gill 

necrosis can lead to respiratory problems and asphyxiation. The protective slime coating on fish 

also may be removed due to corrosive action. 

4.2.2 Measures of Effect (Ecotoxicology Assessment Endpoints)

4.2.2.1 Submitted Data

Ecological effects data are used as measures of direct and indirect effects to aquatic and 

terrestrial organisms. Acute and chronic toxicity data from registrant-submitted studies 

conducted in accordance with the 850 OCSSP Harmonized Test Guidelines will be used to 

evaluate the potential direct and indirect effects of potassium hypochlorite to animals and plants. 

Additionally, as described below, relevant data from the EPA’s Office of Water and from the 

open literature also may be used to evaluate potential direct and indirect effects. 

 

5http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

6http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES

7http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885
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All available ecotoxicity endpoints from studies submitted by registrants are tabulated and 

referenced in the Ecological Effects Profile (Appendix C). OPP uses the most sensitive of these 

endpoints for assessing acute and chronic risks to each aquatic receptor group. The potassium 

ion is an essential, naturally occurring element which is assumed to be non-toxic at the levels 

released by potassium hypochlorite use.

4.2.2.2 Office of Water Data

EPA’s Office of Water’s Ambient Water Quality Criteria for Chlorine8provides additional data 

that will be used in this registration review case. The document contains a review of open 

literature on acute and chronic effects of chlorine. Based on the available toxicological 

endpoints, freshwater and saltwater organism acute and chronic water quality criteria (expressed 

as total residual chlorine (TRC) for freshwater and chlorine-produced oxidants (CPO) for 

seawater) are derived. The current values are as follows:

 Freshwater Criterion Maximum Concentration = 19 μg/L;

 Freshwater Criterion Continuous Concentration = 11 μg/L;

 Saltwater Criterion Maximum Concentration = 13 μg/L; and

 Saltwater Criterion Continuous Concentration = 7.5 μg/L.

4.2.2.3 Open Literature

Since the agency does not anticipating conducting an environmental risk assessment, no effects

analysis plan is needed; therefore no ECOTOxicology (ECOTOX) will be conducted. 

4.3 Exposure Analysis Plan

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates

Since the agency does not anticipate conducting an environmental risk assessment, no exposure 

estimates are needed. 

4.4 Effects Analysis Plan

Since the agency does not anticipate conducting an environmental risk assessment, no effects

analysis plan is needed.

5 Endocrine Disruptor Screening Program (EDSP)

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

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

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

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

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

 

8 See EPA’s Office of Water’s Ambient Water Quality Criteria for Chlorine -1984(EPA, 1985) at:

http://water.epa.gov/scitech/swguidance/standards/upload/2001_10_12_criteria_ambientwqc_chlorine1984.pdf
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organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

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

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

taxonomic groups. As part of its most recent registration decision for potassium hypochlorite,

EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment 

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

potassium hypochlorite is subject to the endocrine screening part of the Endocrine Disruptor 

Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

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

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

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

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

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

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

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

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

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

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

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

which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals 

identified for EDSP screening was published on June 14, 20139and includes some pesticides 

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

construed as a list of known or likely endocrine disruptors. 

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

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

website.10

6 Next Steps

As stated in this work plan, the agency does not anticipate needing any data to support the 

registration review of potassium hypochlorite; furthermore, the agency believes that potassium 

hypochlorite is similar to and can be considered with the chemicals in case 0029, sodium and 

calcium hypochlorite. The docket for the sodium and calcium hypochlorite case opened in March 

of 2012. No risk assessments are considered necessary for any of the three compounds since 

EPA has concluded that the currently registered uses of the hypochlorites will not result in 

 

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

chemicals.

10 http://www.epa.gov/endo/
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unreasonable adverse effects to human health or the environment. Since no risk assessments are 

necessary, after the final workplan for potassium hypochlorite is issued, the agency intends to 

issue a combined proposed decision for all three compounds in September of 2016. 
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7 References 

U.S. Environmental Protection Agency (EPA). 2012.

Registration Review Final Work Plan: Na & Ca Hypochlorite. 

Docket Number EPA –HQ-OPP-2012-0004.

Available at: http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-

0004-0006.
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Appendix A Toxicology Profile

Acute Toxicity for Product Labeling 

No toxicological studies are required to be submitted. All toxicology data are waived based on 

the chemical’s similarity with sodium and calcium hypochlorites. Agency reviews regarding 

potassium hypochlorite have suggested that the registration review of this chemical may be 

treated similarly for the proposed uses. The decision not to require acute toxicity testing is 

supported by the proposed chemicals’ similarities with sodium, calcium and lithium hypochlorite 

and the chlorinated isocyanurates, whose RED documents considered their acute hazard data 

bases to be complete.12

Table 6 – Acute Toxicity Studies for Potassium Hypochlorite

Guideline No./ Study 

Type MRID No. Results Toxicity Category

870.1100/ 

Acute oral toxicity 

Waived N/A IV

870.1200/ 

Acute dermal toxicity 

Waived N/A IV

870.1300/ 

Acute inhalation toxicity 

Waived N/A III

870.2400/ 

Acute eye irritation 

Waived N/A I

870.2500/ 

Acute dermal irritation 

Waived N/A I

870.2600/ 

Skin sensitization 

Waived N/A Non-sensitizer

N/A=Not available 

All studies, subchronic and chronic, are not anticipated to be required for this chemical due to its 

similarities with sodium, calcium and lithium hypochlorite.

 

12 http://www.epa.gov/opp00001/chem_search/reg_actions/reregistration/red_G-77_1-Feb-92.pdf
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Appendix B Environmental Fate and 

Transport of Potassium Hypochlorite 

Office of Chemical Safety and Pollution Prevention (OCSPP) Guideline studies are designed for 

organic compounds and do not provide useful information on inorganic molecules such as 

hypochlorite. 
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Appendix C Ecotoxicology Profile

For the ecotoxicity assessment of potassium hypochlorite, studies testing sodium and calcium 

hypochlorite were used. No studies are available testing the potassium ion. This is acceptable, 

since all hypochlorites have a similar mode of toxicity. They are chlorine releasers, which can 

cause toxicity to non-target organisms. 

Toxicity to Terrestrial Organisms

Birds

An acceptable acute-oral (LD50) study categorizes sodium and calcium hypochlorite as being 

practically nontoxic to birds. The guideline for an acute-oral test (850.2100) is satisfied. Dietary 

studies (850.2200) are not anticipated to be required. However, four dietary studies have been 

submitted and indicate that hypochlorites are practically nontoxic to birds when administered in 

the diet. No additional data avian toxicity data are needed.

Avian Acute-oral and Dietary Toxicity

Test Species Toxicity Toxicity

Category

EPA Study

ID

Mallard

(Anas platyrhynchos) LC50 >5000 ppm Practically nontoxic 00007404

Acceptable

Northern bobwhite

(Colinus virginianus)

LD50 =3474 ppm for Ca 

hypochlorite

LD50 = 2510 for Na 

hypochlorite

Practically nontoxic 00007403Acceptable

LC50 >,5000 ppm Practically nontoxic 00007405

Acceptable

Nontarget Insects 

Toxicity data for beneficial insects (850.3020, 850.3030) are not required for the use patterns of 

potassium hypochlorite. 

Toxicity to Aquatic Organisms

Freshwater Fish 

The available acute toxicity studies categorize sodium and calcium hypochlorite as being highly 

toxic to freshwater fish. The guideline (850.1075) for acute toxicity testing is satisfied. No 

chronic data (fish early-life stage, 850.1400) are available. However, the need for chronic 

toxicity data can be fulfilled from EPA’s Office of Water’s Ambient Water Quality Criteria for 

Chlorine - 1984 (EPA 1985). No additional fish toxicity data are anticipated to be needed. 
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Acute Toxicity to Freshwater Fish

Freshwater Invertebrates

The acute toxicity study for the waterflea categorizes sodium hypochlorite as being very highly 

toxic to freshwater invertebrates. The guideline (850.1010) for acute toxicity testing is satisfied. 

No chronic data (life-cycle, 850.1300) are available. However, the need for chronic toxicity data 

can be fulfilled from EPA’s Office of Water’s Ambient Water Quality Criteria for Chlorine -

1984 (EPA 1985). No additional aquatic invertebrate toxicity data are anticipated to be needed. 

Toxicity to Freshwater Invertebrates

Test Species Toxicity Endpoint

(μg ai/L)

Toxicity

Category

EPA Study

ID

Waterflea

(Daphnia magna)

48-hr EC50 = 0.037 to 2.3 

ppm

Very highly toxic

00007402

00019313

Acceptable

Estuarine/Marine Fish and Invertebrates 

The agency anticipates using the available data from EPA’s Office of Water’s Ambient Water 

Quality Criteria for Chlorine - 1984 (EPA 1985).

Test Species Toxicity Endpoint

(μg ai/L)

Toxicity

Category

EPA Study

ID

Rainbow Trout

(Oncorhynchus 

mykiss) 96-hr LC50 =0.13 to 1.35 

ppm

Highly toxic 00008191

Acceptable

Bluegill

(Lepomis 

macrochirus) 96-hr LC50 =0. 28 to 2.1 

ppm

Highly toxic 00008190

Acceptable

Test Species Toxicity Endpoint

(μg ai/L)

Toxicity

Category

EPA Study

ID
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Aquatic Plants 

No data are available. Studies needed for the TGAI include a toxicity test with a vascular 

species (850.4400), toxicity tests (850.4500) with 3 algal species (green algae, freshwater 

diatom, marine diatom), and a toxicity test using cyanobacteria (850.4550); to address these 

needs, the agency anticipates using the available data from EPA’s Office of Water’s Ambient 

Water Quality Criteria for Chlorine - 1984 (EPA 1985).

Sediment toxicity

Based on the environmental-fate properties of potassium hypochlorite (see section 4.1), sediment 

toxicity data are not anticipated to be required.

Appendix C References

00007403 Beavers, J.B.; Fink, R.; Grimes, J.; et.al. (1978) Final Report: Acute Oral LD50-

Bobwhite Quail: Project No. 158-103. (Unpublished study received Jan 19 under

unknown admin. No.; prepared by Wildlife International, Ltd. In cooperation with

Washington College, submitted by Chlorine Institute, Inc., New York, N.Y.;

CDL236804-B)

00007404 Beavers, J.B.; Fink, R.; Grimes, J.; et.al. (1978) Final Report: Eight-Day Dietary

LC50-mallard Duck: Project No. 158-102. (Unpublished study received Jan 19, 

1979. Under unknown admin. No.; prepared by Wildlife International, Ltd. In 

cooperation with Washington, submitted by Chlorine Institute, Inc., New York, 

N.Y.; CDL:236804-C)

00007405 Beavers, J.B.; Brown, R. (1978) Final Report: Eight-Day Dietary LC50-Bobwhite

Test Species Toxicity Endpoint

(μg ai/L)

Toxicity

Category

EPA Study

ID

Marine Fish

(Cyprinodon 

variegates)

96-hr LC50 =0.38 mg/L

NOAEC = 0.225 mg/ Highly toxic 47642401Acceptable

Mysid Shrimp

(Americamysis

bahia)

96-hr LC50 =0.16 mg/L

NOAEC = 0.14 mg/ Highly toxic

47642402

Acceptable

Eastern Oyster

(Crassostrea 

virginica)

96-hr EC50 =0.20 mg ai /L

NOAEC = 0.13 mg ai/L Highly toxic

47642403

Acceptable
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Quail: Project No. 158-101. (Unpublished study received Jan 19, 1979 under 

unknown admin. No.; prepared by Wildlife International, Ltd., submitted by 

Chlorine Institute, inc., New York, N.Y.; CDL:236804-D)

00008190 Calmbacher, C.W. (1978) Acute Toxicity of Sodium hypochlorite Solution to the

Bluegill Sunfish “Lepomis macrochirus” Rafinesque: UCES Proj. No. 11506-72-

01. (Unpublished study received Apr 4, 1978 under 35317-1; prepared by Union 

Carbide Corp., submitted by Kuehne Chemical Co., Inc., Cranford, N.J.; 

CDL:233389-A)

00008191 Calmbacher, C.W. (1978) Acute Toxicity of Sodium hypochlorite Solution to the

Rainbow Trout, “Salmo gairdneri” Richardson: UCES Project. No. 11506-72-02.

(Unpublished study received Apr 4, 1978 under 35317-1; prepared by Union 

Carbide Corp., submitted by Kuehne Chemical Co., Inc. Cranford, N.J.; 

CDL:233390-A)

00019313 LeBlanc, G.A. (1977) Acute Toxicity for Sodium hypochlorite Solution to the 

Water Flea (Daphnia magna): ICG/T-78-076. (Unpublished study received Dec 7, 

1978 under 230-69; prepared by EG&G, Bionomics, submitted by FMC Corp., 

Industrial Chemical Group, Philadelphia, Pa.; CDL:236584-B)

47642401 MacGregor, R. (2008) Marine Fish (Cyprinodon variegates) Definitive 96-hour

Acute Toxicity Test with Daily Dosing. Prepared by Baroid Bioassay Lab; 

submitted by Halliburton Energy Services, Inc, OK; Study No.: S4546

47642402 MacGregor, R. (2008) Mysid Shrimp (Americamysis bahia) Definitive 96-hour 

Acute Toxicity Test with Daily Dosing; prepared by Baroid Bioasssay Lab; 

submitted Halliburton Energy Services, OK; Study No.: S4547

47462403 Gallagher, S.P.; Kendall, T.Z.; Krueger, H.O. (2008) BE-7 antimicrobial (Sodium

Hypochlorite 12.5% w/v): A 96-hour Shell Deposition Test with the Eastern 

Oyster (Crassostrea virginica); prepared by Wildlife International, Ltd; submitted 

by Halliburton Energy Services, Inc., OK; Study No.: 666A-101
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Appendix D Product Chemistry

Potassium hypochlorite product chemistry information is summarized in Table D1 (source: 

MRIDs 47382901, 47445101, and 47594501).

Table D1 – Product Chemistry of Potassium hypochlorite

Guideline 

No. Physical and Chemical Properties Potassium hypochlorite

830.1550 Product identity and composition Refer to Table 3. 

830.1600 Description of materials used to produce 

the product

Confidential Business Information (CBI).

830.1620 Description of production process CBI.

830.1650 Description of Formulation Process CBI.

830.1670 Discussion of Formation of Impurities CBI.

830.1700 Preliminary analysis CBI.

830.1750 Certified limits CBI.

830.1800 Enforcement analytical method 

The enforcement analytical method for potassium hypochlorite 

solutions is based on ASTM D 2002-89(2003) entitled 

“Standard Test Methods of Sampling and Chemical Analysis of 

Chlorine-Containing Bleaches”.

830.1900 Submittal of samples CBI.

830.6302 Color Pale yellow.

830.6303 Physical State Aqueous solution- pale yellow.

Liquid at 20.1°C.

830.6304 Odor Chlorine bleach smell.

830.6313 Stability to normal and elevated 

temperature, metals/metal ions 

Stable under ordinary conditions of use and storage. 

Unstable at elevated temperatures. 

Reacts vigorously with amine, ammonium, salts, reducing 

agents, methanol, acids and most organics. 

Strong reducing agents such as nitrites, sulfides, sulfites, 

metabisulfites, and thiosulfates are incompatible, and their 

contact with potassium hypochlorite should be prevented.

830.6314 Oxidation/Reduction Strong Oxidizing Agent.

830.6315 Flammability Not applicable. Noncombustible.

830.6316 Explodability Not explodable.

830.6320 Corrosion Characteristic

Corrosive.

Potassium hypochlorite solution is corrosive to metals such as 

stainless steel, mild steel, iron, copper, zinc, and aluminum. 

Potassium hypochlorite solution should not contact these 

materials.

830.7000 pH 10.14 - 1% w/w solution in de-ionized water at 21.1-21.8°C.

830.7050 UV/Visible Absorption Not reported.

830.7100 Viscosity 1.1 mm2/sec at 20.6°C and 0.9 mm2/sec at 40°C.

830.7200 Melting point Not required.

830.7220 Boiling point Decomposes prior to boiling.

830.7300 Density 1.1701 g/ml (9.75 lbs/gal) at 20.1°C.
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Guideline 

No. Physical and Chemical Properties Potassium hypochlorite

830.7370 Dissociation Constant Potassium hypochlorite dissociates completely on dissolving 

in water.

830.7550 Partition coefficient (n-octanol/water) Not applicable.

830.7840 Solubility in water Complete.

830.7860 Solubility in organic solvents NA Product should be mixed only with water.

830.7950 Vapor pressure Approximately that of air.

A Confidential business information

atm-m3/mol = atmosphere cubic meter per mole; oC = degrees Celsius; mg/L = milligrams per liter; mmHg = 

millimeters of mercury.