Page 2 of 77
DCOIT Registration Review Team

Human Health & Environmental Effects

Siroos Mostaghimi

James Breithaupt

David Bays

Jonathan Chen

Nathan Mottl

Don Wilbur

Risk Management

SanYvette Williams

Rose Kyprianou

Seiichi Murasaki

Office of General Counsel

Philip Ross

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

CAS Chemical Abstracts Service 

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 

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

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act

FQPA Food Quality Protection Act 

Page 3 of 77
FWP Final Work Plan

g/mol grams per mole

GLN guideline number

HPV high production volume

IDS Incident Data System 

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

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 

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

TEP typical end-use product

TGAI technical grade active ingredient

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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 .............................................................................................................................8

1.1 Statutory and Regulatory Authority .................................................................................8

1.2 Updates to the Work Plan...............................................................................................10

1.3 Case Overview................................................................................................................11

1.4 Chemical Identification and Properties ..........................................................................11

1.5 Use/Usage Description ...................................................................................................12

1.5.1 Registrations............................................................................................................12

1.5.2 Summary of Registered Uses..................................................................................12

1.5.3 Usage Information...................................................................................................13

1.6 Regulatory History .........................................................................................................13

1.6.1 Tolerance Information (Antimicrobial Uses)..........................................................13

1.7 Incidents..........................................................................................................................14

1.7.1 Human Health .........................................................................................................14

1.7.2 Ecological................................................................................................................14

2 Anticipated Data Needs.........................................................................................................15

3 Human Health Risk Assessment ...........................................................................................16

3.1 Existing Toxicological Endpoints ..................................................................................17

3.2 Dietary Exposure ............................................................................................................18

3.2.1 Food.........................................................................................................................18

3.2.2 Drinking Water........................................................................................................19

3.3 Occupational and Residential Exposures .......................................................................19

3.3.1 Occupational Handler Exposure..............................................................................19

3.3.2 Residential Handler Exposures ...............................................................................20

3.3.3 Residential Post-Application Exposures.................................................................20

3.4 Aggregate and Cumulative Exposure .............................................................................20

3.4.1 Aggregate Exposures...............................................................................................20

3.4.2 Cumulative Exposures.............................................................................................21

4 Environmental Risk Assessment...........................................................................................21

4.1 Environmental Fate Assessment.....................................................................................21

4.1.1 Leaching (Wood/Antifoulant).................................................................................22

4.1.2 Water and Sediment ................................................................................................22

4.1.3 WWTP.....................................................................................................................23

4.1.4 Water Quality ..........................................................................................................24

4.2 Ecological Effects Assessment.......................................................................................24

4.2.1 Mechanism of Action ..............................................................................................24

4.2.2 Measures of Effect (Ecotoxicology Endpoints) ......................................................24

4.3 Exposure Analysis Plan ..................................................................................................25

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates.............................................25

4.3.2 Screening Level Down-the-Drain Analysis ............................................................26

4.4 Effects Analysis Plan......................................................................................................27

5 Endocrine Disruptor Screening Program (EDSP).................................................................27

6 Optional Label Changes........................................................................................................28

7 Next Steps .............................................................................................................................29

8 References.............................................................................................................................30

Page 6 of 77
Appendix A Toxicology Profile...............................................................................................31

Appendix B Environmental Fate..............................................................................................41

Appendix C Ecotoxicology Profile ..........................................................................................58

Appendix D Screening Level Down-the-Drain Analysis.........................................................73

Appendix E Product Chemistry ...............................................................................................74

Appendix F Public Comments Received on the Preliminary Work Plan................................76

List of Tables

Table 1 – Summary of Anticipated Risk Assessments and Data Needs for Registration Review: 

DCOIT............................................................................................................................................... 9

Table 2 – Anticipated Registration Review Schedule..................................................................... 10

Table 3 – Chemical Identification of 3(2H)-isothiazolone, 4,5-dichloro-2-octyl- (DCOIT).......... 11

Table 4 – Physical-Chemical and Environmental Fate Properties for 3(2H)-isothiazolone, 4, 5-

dichloro-2-octyl-(DCOIT)............................................................................................................... 11

Table 5 – Summary of DCOIT Registered End Uses ..................................................................... 12

Table 6 – Studies Anticipated as Needed for the Registration Review of DCOIT......................... 15

Table 7 – Existing Toxicological Endpoints for DCOIT ................................................................ 17

Table 8 – Occupational Handler Exposure Scenarios for DCOIT.................................................. 20

Table 9 – Residential Handler Exposure Scenarios for DCOIT ..................................................... 20

Table 10 - Summary of Environmental Fate Data for DCOIT in Water and Sediment.................. 23

Table 11– Ecological Effects Endpoints Selected for Assessing Risks from DCOIT Use............. 24

Table 12 - Results of a Screening Level Down-the-Drain Analysis for DCOIT ............................ 26

Page 7 of 77
1 Introduction

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

agency”) Final Work Plan (FWP) for 3(2H)-isothiazolone, 4,5-dichloro-2-octyl (DCOIT). The 

FWP document explains what EPA's Office of Pesticide Programs (OPP) knows about DCOIT, 

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 DCOIT’s review. This work plan also addresses the public comments 

received concerning the Preliminary Work Plan (PWP) which was posted in the DCOIT 

registration review docket (EPA-HQ-OPP-2014-0403). Further, this document makes final the 

work plan for the DCOIT registration review process.

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://www2.epa.gov/pesticidereevaluation.

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. The public comment 

period for the preliminary work plan (PWP), published September 24, 2014, closed November 24, 

2014. As stated in Appendix F, comments were submitted by the FIFRA Endangered Species Task 

Force (FESTF) and by Dow Chemical Company. After reviewing and responding to the comments 

received in the docket, the agency has developed a Final Work Plan (FWP) which includes an 

anticipated schedule for the DCOIT case.

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

in docket EPA-HQ-OPP-OPP-2014-0403. Tables 1 and 2 below summarizes the issues relevant to 

this registration review case and the anticipated registration review schedule. 

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Table 1 – Summary of Anticipated Risk Assessments and Data Needs for Registration 

Review: DCOIT

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) Yes None New None

Dietary (drinking water) Yes 9/2013 New None

Occupational Handler Yes 1/2008 Updated

875.1200 Dermal Exposure – Indoor

875.1400 Inhalation Exposure – Indoor

875.1700 Product Use

870.3700 Rabbit Developmental Toxicity

870.7800 Immunotoxicity

Residential Handler Yes 1/2008 Updated

875.1200 Dermal Exposure – Indoor

875.1400 Inhalation Exposure – Indoor

875.1700 Product Use

870.3700 Rabbit Developmental Toxicity

870.7800 Immunotoxicity

Residental Post 

Application - Incidental 

Oral and Dermal 

No 9/2013 None None

Residental Post 

Application - Inhalation No None None None

Aggregate Yes None New None

Cumulative No None None None

Ecological Yes N/A New

Activated sludge respiration inhibition 

(850.3300)

Honeybee acute contact (850.3020)

N/A = Not applicable

* Table 1 is a summary of the anticipated risk assessments and data needs for Registration Review.

Page 9 of 77
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 2014-09 2014-24-09

Close Public Comment Period 2014-11 2014-24-11

Phase 2: Case Development 

Issue Final Work Plan 2015-03 2015-03

Issue Data Call-In (DCI) 2016-03

Receive Data to be Considered in Risk Assessment 2018-03

Open 30-Day Public Comment Period for Preliminary Risk Assessment(s) 2019-09

Close Public Comment Period 2019-10

Phase 3: Registration Review Decision and Implementation 

Open 60-Day Public Comment Period for Proposed Decision 2020-03

Close Public Comment Period 2020-05

Issue Final Decision 2020-09

Begin Post-Decision Follow up 2020

Total (years) 6

*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).

1.2 Updates to the Work Plan

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

• Updated Table 2 – Anticipated Registration Review Schedule to reflect comment period 

completion date.

• Added information to Section 1.6.1 on the existing of Food Contact Notification (FCN)

allowing uses as a slimicide, mold-proof agent and preservative.

• Revised 3.2 Dietary Exposure and 3.2.1 Food sections to reflect the need for assessments. 

This includes an interim, screening-level assessment on DCOIT migration from treated 

paper products into food. 

• Updated Table 5 - Corrected maximum use rate values.

• Table 6 – corrected guideline number for Rabbit Developmental Toxicity study and 

updated test substances for 875.1200 and 875.1400.

• Updated Table 9 – Added “latex” for the do-it-yourself scenario assessment.

• Added to Section 6 Optional Label Changes – that the Acticide PDP 20-F should not be 

used for adhesives that may come in contact with food.

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• Deleted “Guidance for Commenters” section.

• Updated Next Steps section.

• Added Appendix F Public Comments Received on the Preliminary Work Plan.

• Corrected formatting and typographical errors and made other editorial changes.

1.3 Case Overview

The docket for 3(2H)-isothiazolone, 4,5-dichloro-2-octyl-(DCOIT) (case 5023) has been 

established at http://www.regulations.gov in docket number EPA-HQ-OPP-2014-0403.

1.4 Chemical Identification and Properties

Table 3 presents the active ingredient to be assessed in case 5023: DCOIT (PC Code 128101).

Table 3 – Chemical Identification of 3(2H)-isothiazolone, 4,5-dichloro-2-octyl- (DCOIT)

Chemical Name 3(2H)-isothiazolone, 4,5-dichloro-2-octyl-(DCOIT)

Chemical Classification Isothiazolone

PC Code 128101

CAS Number 64359-81-5

Molecular Formula C11H17Cl2NOS

Molecular Weight (grams/mole) 281.040802

Molecular Structure

The 3(2H)-isothiazolone, 4,5-dichloro-2-octyl- DCOIT product chemistry information (MRID 

40808501 and 41351601) relevant to risk assessment is summarized in Table 4 and the details of 

the product chemistry are discussed in Appendix E.

Table 4 – Physical-Chemical and Environmental Fate Properties for 3(2H)-isothiazolone, 4, 

5-dichloro-2-octyl-(DCOIT)

Guideline No. Parameter 3(2H)-isothiazolone, 4,5-dichloro-2-octylPhysical/Chemical Properties

830.7000 pH Not required

830.7050 UV/Visible Absorption Not reported

830.7200 Melting point (

o

C) 40-41oC

830.7220 Boiling point (

o

C) Decomposes before boiling

830.7300 Density 1.28 g/ml at 25oC (melted and solidified)

830.7370 Dissociation constant (pKa) Not required

830.7550 Octanol-water partition coefficient at 25 o

C 

(Log Kow) 2.8

830.7840 Solubility in water (mg/L) 14 ppm at 25oC

830.7950 Vapor pressure (mmHg) 4.5 x 10-6 mm Hg

Page 11 of 77
Guideline No. Parameter 3(2H)-isothiazolone, 4,5-dichloro-2-octylNone (calculated)1 Henry's law constant at 25 o

C (atm-m3/mol) 1.2 x 10-7

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 are 27 products (three are manufacture use products or MUPs) registered for uses for 

incorporation into products such as adhesives, coatings, fuels, metal working fluids (MUP only), 

resin emulsions, paints and various other specialty industrial products (as a preservative); and, as a 

microbiocide in pulp/paper mills, cooling water systems, oil field operations (MUP only), 

industrial process waters and air washers systems. The compound is also registered for use to treat 

wood products (seasoned/unseasoned forest products and various finished wood products).

The manufacturing use product (EPA Reg # 707-224) specifies several uses (sapstain, in-can 

preservatives for laundry detergents and household cleaners, oil injection waters and metal 

working fluid preservatives) that have no registered end-use product labels, application rates or 

directions for use. 

1.5.2 Summary of Registered Uses

Table 5 presents a summary of the registered uses of DCOIT that will be assessed in this 

registration review. DCOIT can be applied by the following application methods: liquid open 

pour, wood pressure treatment, airless spray, dip or brush. The product is sold as ready-to-use 

solutions. Since there are certain uses on MUPs for products EPA Reg #s 707-224 and 67071-58

but not on EUPs that include directions for use and application rate, these uses will not be assessed 

as part of registration review because they cannot be used on any EUP until added to a EUP label. 

The EPA encourages the registrant to amend these uses. If they are amended to add the uses to the 

EUP in the future, the agency would assess this amendment as a new use under PRIA.

Table 5 – Summary of DCOIT Registered End Uses

Use Application Method Application Rate

(ppm a.i.)

Industrial Process and Water Systems

Recirculating Cooling Tower +

Air Washer Water+

Ornamental Fountains+

Brewery Pasteurizer

Open Pour, Metered Pump 6 ppm

6 ppm

6 ppm

6 ppm

Material Preservative

Adhesives, industrial

Caulks

Open Pour and Metered Pump 2,000 ppm

2,000 ppm

Page 12 of 77

 
Use Application Method Application Rate

(ppm a.i.)

Coatings, industrial

Emulsions, resin/latex/polymer

Paints (in-can)

Paints, latex/oil/varnish and applied film

Paints, latex/oil/varnish 

Pulp+

Plastics/Rubber products++

2,000 ppm

2,000 ppm

2,000 ppm

2,000 ppm

Brush, Roller and Airless Spray 2,000 ppm

Open Pour and Metered Pump 100 ppm

0.2 lb ai/ton

2,000 ppm

Wood Preservative

Wood pressure treatment to forest products Pressure Treatment 500-1,600 ppm

Antifoulant Paints and Coatings

Paints, latex/oil/varnish (applied film) Bush, Airless Spray, and Roller 192 sq ft/gallon

3.6%

+ EPA Reg 707-259

++ Plastic uses do not include toys or pacifiers and plastics are not to contact food. 

1.5.3 Usage Information

According to the Kline Biocides Report for 2004/2005 (Kline, 2005), ~56,000 lb of DCOIT was 

estimated to be produced in 2004. 

1.6 Regulatory History

DCOIT was first registered in the United States January 24, 1983.

1.6.1 Tolerance Information (Antimicrobial Uses)

For the active ingredient DCOIT, EPA has not established tolerances or exemptions from 

tolerances in raw agricultural commodities or processed food and feed products under FFDCA 

Section 408. The US Food and Drug Administration (US FDA) has established a Food Contact 

Notification (FCN No. 11) for the Rohm and Haas Company. This FCN was established April 1, 

2000 and allows for the following uses: 1. As a slimicide, in compliance with 21 CFR 176.300, at 

a maximum level of 0.034 pound per ton of dry weight fiber. 2. As a mold-proofing agent applied 

to the surface of uncoated paper and paperboard and in coatings for paper and paperboard, in 

compliance with 21 CFR 176.170(b), at a level not to exceed 100 parts per million (ppm) based on 

dry fiber weight. 3. As a preservative in wet lap and sheet pulp, in compliance with 21 CFR 

176.170(a) prior to repulping to produce paper and paperboard, at a level not to exceed 100 parts 

per million (ppm) based on dry fiber weight. 4. As a preservative in pigment dispersions, in 

compliance with 21 CFR 176.170(b), at a level not to exceed 50 parts per million (ppm).

Page 13 of 77
1.7 Incidents

1.7.1 Human Health 

There are no human health incidents listed in the OPP Incident Data System (IDS) for the period 

9/2001 to the present (search conducted on 5/25/2014). 

1.7.2 Ecological

There are no aquatic or terrestrial wildlife incidents listed in the OPP Incident Data System (IDS) 

for the period 9/2001 to the present (search conducted on 5/7/2014).

Page 14 of 77
Docket Number EPA-HQ-OPP-2014-0403

www.regulations.gov

2 Anticipated Data Needs

Table 6 – Studies Anticipated as Needed for the Registration Review of DCOIT

GLN Study Name Test 

Substance

Time Frame 

(Measured in months 

from DCI Receipt)

Risk Assessment(s) Data 

Will Support

Use Site(s) Triggering 

Anticipated Data 

Requirement

Applicable Exposure 

Scenario

Studies Anticipated to be Required through the Registration Review DCI

850.3300 (Modified) Activated 

sludge respiration 

inhibition (ASRI)

TGAI 12 months Ecological Assessment Down-the-drain uses Cooling towers

850.3020 Honeybee acute contact TGAI 12 months Ecological Assessment Wood preservative uses Wood treatment

870.3700 Rabbit Developmental

Toxic TGAI 24 months Occupational and Residential Assessment All All

870.7800 Immunotoxicology TGAI 24 months Occupational and 

Residential Assessment All All

875.1200 Indoor Dermal 

Exposure TEP 24 months Occupational and 

Residential Assessment All

Pour liquids

Brush/Roller

Airless Sprayer

Pressure treatment

875.1400 Indoor Inhalation 

Exposure TEP 24 months Occupational and 

Residential Assessment All

Pour liquids

Brush/Roller

Airless Sprayer

Pressure treatment

875.1700 Product Use TGAI 12 months All All All

Page 15 of 77
Docket Number EPA-HQ-OPP-2014-0403

www.regulations.gov

3 Human Health Risk Assessment

The agency anticipates the need to conduct a human health risk assessment for DCOIT. The 

agency anticipates issuing a generic data call-in (GDCI) which will require additional data for 

use in conducting the registration review risk assessment. On November 16, 1999, the Health 

Effects Division's Hazard Identification Assessment Review Committee (HIARC) evaluated the 

toxicology database of DCOIT, and selected the toxicological endpoints for acute and chronic 

dietary as well as occupational and residential exposure risk assessments. The HIARC also 

addressed the potential sensitivity of infants and children from exposure to DCOIT as required 

by the Food Quality Protection Act (FQPA) of 1996. A FQPA Safety Factor of 1x was selected 

for dietary risk assessments.

On May 10, 2007, the Antimicrobials Division Toxicity Endpoint Selection Committee (ADTC) 

revised the original endpoint selection in 1999, based on additional data submitted, including a 

reproductive toxicity study, open literature information on neurotoxicity, and a 21-day dermal 

toxicity. Incidental oral endpoints were selected and added to the endpoint report. The 

conclusions presented in the 2007 ADTC report superseded the conclusions of the original 1999 

HIARC report. 

On December 6, 2007, the Health Effects Division's Hazard Science Policy Council (HASPOC) 

met to discuss whether the need for a chronic/cancer rodent bioassay study on DCOIT was 

justified based on the available chemistry, metabolism, and toxicity information for DCOIT and 

other isothiazolone biocides. Based on the available evidence for DCOIT and other members of 

isothiazolone biocides, the HASPOC concluded that “the absence of a chronic bioassay would 

not likely impact the risk assessment on DCOIT”. 

On July 9, 2013, the ADTC met to revise the chronic Reference Dose (RfD) for DCOIT. The

existing toxicological end-points selected are summarized in Table 7. Endpoints will be revised 

as appropriate based on the data to be required through the DCI for this registration review. A 

detailed description of the toxicity studies is provided in Appendix A.

Page 16 of 77
3.1 Existing Toxicological Endpoints

Table 7 – Existing Toxicological Endpoints for DCOIT

Exposure 

Scenario

Dose Used in Risk 

Assessment 

(mg/kg/day)

Target Margin of 

Exposure (MOE), 

Uncertainty Factor (UF), 

FQPA Safety Factor (SF)

Study and Toxicological Effects

Dietary Risk Assessments

Acute Dietary 

(females 13-49) 

NOAEL

(developmental) = 

30 mg/kg/day 

FQPA SF = 1x

UF = 100 (10x interspecies extrapolation, 10x 

intra-species variation)

Acute RfD (aPAD) = 0.3 

mg/kg/day

Developmental toxicity study – Rat 

(MRID 43471604)

LOAEL = 100 mg/kg/day based on 

increased incidence of wavy ribs. 

Acute Dietary 

(general 

population) 

NOAEL (maternal) 

= 30 mg/kg/day 

FQPA SF = 1x

UF = 100x (10x interspecies extrapolation, 10x 

intra-species variation)

Acute RfD (aPAD) = 0.3 

mg/kg/day

Developmental toxicity study – Rat 

(MRID 43471604)

LOAEL = 100 mg/kg/day based on 

increased incidence of wavy ribs. 

Chronic Dietary

(all populations)

NOAEL (offspring) 

= 16 mg/kg/day

FQPA SF = 1x

UF = 100 (10x interspecies extrapolation, 10x 

intra-species variation)

Chronic RfD (cPAD) = 

0.16 mg/kg/day

Reproduction toxicity study – Rat 

(MRID 45756501)

Offspring LOAEL = 30 (M) and 33(F) 

mg/kg/day, based on decreased spleen 

and thymus weights. 

Non-Dietary Risk Assessments

Incidental Oral

Short-Term (1-

30 days)

Intermediateterm(30-days –

6months) 

NOAEL (offspring) 

= 16 mg/kg/day

Target MOE = 100

(10x inter-species 

extrapolation, 10x intraspecies variation) 

Reproduction toxicity study – Rat 

(MRID 45756501)

Offspring LOAEL = 30 (M) and 33(F) 

mg/kg/day, based on decreased spleen 

and thymus weights. 

Dermal

Short-Term (1 to 

30 days) and 

Intermediateterm (30 days- 6 

months)

LOAEL = 32 

μg/cm2

Target MOE = 100

(10x inter-species 

extrapolation, 3x intraspecies variation, 3x for 

lack of derived 10% 

response level)

Dermal sensitization study – guinea pigs 

(MRID 47004002)

LOAEL = 32 μg/cm2 based on positive 

dermal sensitization response. 

Dermal

Long-Term (>6 

months)a

NOAEL = 10 

mg/kg/day 

Target MOE = 300

(10x inter-species 

extrapolation, 10x intraspecies variation; 3x for 

lack of chronic study)

90-day oral toxicity study – Dog 

(MRID 45747201)

LOAEL (systemic) = 46 mg/kg/day, 

based on decreased body weight and 

food consumption and alterations in 

hematology and clinical chemistry.

Page 17 of 77
Exposure 

Scenario

Dose Used in Risk 

Assessment 

(mg/kg/day)

Target Margin of 

Exposure (MOE), 

Uncertainty Factor (UF), 

FQPA Safety Factor (SF)

Study and Toxicological Effects

Inhalation

(all durations)

NOAEL = 0.02 

mg/m3 

Target MOE = 100

(10x inter-species 

extrapolation, 10x intraspecies variation)

90-day Inhalation toxicity study –rat

(MRID 43487501)

LOAEL = 0.63 mg/m3, based on 

histopathological alterations of the nose, 

lung, and larynx. 

Cancer The Health Effects Division’s HASPOC committee determined that a cancer study would 

not likely impact the risk assessment for DCOIT, and is not required for DCOIT at this time. a Based on the results of a dermal absorption study (MRID # 43471610), a dermal absorption value of 50% will be used in dermal risk 

assessments. 

* FQPA SF = FQPA safety factor.

3.2 Dietary Exposure

The agency anticipates the need to conduct a dietary exposure (food only) assessment to support 

registration review since no previous dietary assessments have been conducted for DCOIT. 

There are several approved uses of DCOIT that may result in dietary (food) exposure, including:

in-container materials preservatives in household cleaners, dishwashing detergents, and sponges

and use in pulp and papermills to control fungal, bacterial, and algal growth on paper and 

paperboard machines, for preparation of mold-resistant food-contact paper or paperboard, and 

the preservation of wet-lap or sheet pulp. With respect to drinking water exposure, several 

approved uses may result in DCOIT being discharged into waste water and subsequently running 

off into surface water, which will need to be assessed to support registration review.

3.2.1 Food

The agency anticipates the need to conduct dietary exposure assessments as part of the 

registration review process since none have been previously conducted. Current uses as in-can 

materials preservatives and in/on food contact paper and paperboard may result in dietary (food) 

exposure. 

Residue chemistry data are not anticipated to be required at this time. The dietary exposure 

contribution will be considered in the aggregate assessments conducted during registration 

review. If the toxicological point of departure for either the acute or chronic scenario changes 

during the registration review process, additional residue chemistry data may be necessary. 

In the interim, a screening-level assessment was completed to estimate the amount of DCOIT 

that may migrate from treated paper products into food using updated assumptions (20% of food 

consumed in the human diet may contact paper; 100 pounds of slurry contains 1 pound of pulp 

by weight) and NHANES/WWEIA 2003-2008 consumption data. Exposure estimates for the 

treated paper products utilized <1% of the aPAD and <1.5% of the cPAD for the general U.S. 

population, and utilized ≤3% of the aPAD and ≤6% of the cPAD for children 1-2 years old, the 

most highly-exposed population subgroup (aPAD=0.3 mg/kg/day; cPAD = 0.16 mg/kg/day). 

Page 18 of 77
Screening-level assessments were not completed for the in-can materials preservative uses since 

there do not appear to be end-use products associated with the technical label.

3.2.2 Drinking Water

A quantitative drinking water assessment was conducted based on pressure-treated wood for 

fresh water use in 2013. Acute dietary risks to adults and children from consuming DCOITcontaminated drinking water were less than 1% of the aPAD and chronic dietary risks to adults 

and children were also less than 1% of the cPAD. These conservative estimates were well below 

the agency's levels of concern (100% of the respective PAD). The agency anticipates the need to 

refine these estimates to consider exposure to down-the-drain, antifoulant paint and pressure 

treated wood scenarios.

3.3 Occupational and Residential Exposures

The agency anticipates the need to develop a new occupational and residential (ORE) 

assessment. EPA identified existing agency risk assessments of the wood pressure treatment and 

antifoulant uses. However, EPA anticipates that an ORE assessment will be needed for uses that 

have not been assessed (e.g., latex paint, and industrial process and water system uses). Also, 

EPA may need to update the ORE for uses that already have been assessed (antifoulant paint and 

wood treatment) as a result of new data and new approaches. EPA anticipates the need for 

exposure data to assess these use scenarios in registration review. 

3.3.1 Occupational Handler Exposure

Occupational handler exposures were assessed for registration in 2008 for pressure treatment of 

wood preservative uses (D330114 and D340329) and for the antifoulant paint uses (D252378) in 

1999. For the wood preservative uses, the inhalation exposures were assessed using the Human 

Equivalent Concentration (HEC) of 0.0024 mg/m3 from a 90 day inhalation rat toxicity study in 

the ORE (D330114 and D340329). The resulting MOEs ranged from 21 to 120, most scenarios

were greater than the target inhalation MOE of 30. The scenarios which resulted in MOEs of 

potential concern included treatment operators, treatment assistants, and packagers. The dermal 

exposures for short and intermediate-term exposures were not assessed for the occupational 

handler because the endpoint is based on dermal sensitization. Instead, dermal sensitization 

exposures need to be mitigated using personal protective equipment requirements. Chronic 

dermal exposures were above the target MOE of 300 and were not of concern. EPA will reassess 

the pressure treatment wood uses in registration review upon receipt of the anticipated exposure 

data.

The agency assessed antifouling paint uses in 1999. The agency also assessed occupational 

handler exposure to airless sprayer for antifoulant paints in 1999. The results indicated potential 

dermal MOEs of concern for applicators were less than the target MOE of 100. The agency plans 

to reassess this exposure scenario with updated exposure data for antifoulant paints during 

registration review

The occupational handler scenarios as listed in Table 8 will need to be assessed during 

registration review. 

Page 19 of 77
Table 8 – Occupational Handler Exposure Scenarios for DCOIT

Scenario Exposure Route(s) Duration

Open Pour Addition for Industrial Process/Water Systems 

Treatment and Material Preservation

Dermal, Inhalation Short and Intermediate 

Term

Brush/Roller Application of preserved paints, antifouling paints, 

and stains Dermal, Inhalation Short and Intermediate Term

Airless sprayer application of preserved paints, antifouling paints, 

and stains Dermal, Inhalation Short and Intermediate Term

Wood Pressure Treatment Dermal ,Inhalation Short and Intermediate 

Term

3.3.2 Residential Handler Exposures

Residential handler dermal and inhalation exposures to DCOIT were not assessed for the 

application of treated latex paints and stains, but would need to be assessed during registration 

review. The residential handler scenario as listed in Table 9 will need to be reassessed during 

registration review to utilize the exposure data that are anticipated to be needed for registration 

review. 

Table 9 – Residential Handler Exposure Scenarios for DCOIT

Scenario Exposure Route(s) Duration

Brush/Roller and Airless Spray application of latex paints and 

stains Dermal, Inhalation Short and Intermediate Term

3.3.3 Residential Post-Application Exposures

Residential post application exposures were assessed for dermal irritation and incidental 

ingestion exposure to pressure treated wood. Potential dermal and incidental oral exposure of 

children can result while playing on DCOIT-treated structures such as decks and/or play sets. 

Both the ST-dermal and the ST-incidental oral MOEs were above the target MOE of 100. The 

agency does not anticipate that a new residential post-application assessment is needed unless 

toxicological endpoints, exposure algorithms or application rates change. The residential postapplication exposure MOEs for the wood preservative uses were initially determined in the ORE 

2008 (D330114 and D340329) and then reassessed in 2013 in the human health risk assessment 

(D405995). The recalculated MOEs were above the target MOE of 100. 

Residential post-application inhalation exposures from treated paint (e.g., treated hard 

surfaces/walls) are not expected since the vapor pressure is low (4.5 x 10-6 mm Hg) and exposure 

is expected to be minimal.

3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures 

EPA anticipates the need to conduct an aggregate assessment as part of this registration review. 

An aggregate risk assessment considers food, drinking water, residential, and any other nonPage 20 of 77
occupational sources of exposure for which there are reliable data. For DCOIT, aggregate 

exposure may result from wood treatment and antifoulant paint uses and there are currently FDA 

dietary uses for pulp and paper. 

3.4.2 Cumulative Exposures 

With respect to cumulative exposure, unlike other pesticides for which EPA has followed a 

cumulative risk approach based on a common mechanism of toxicity, EPA has not made a 

common mechanism of toxicity finding as to DCOIT and any other substances and DCOIT does 

not appear to produce a toxic metabolite produced by other substances. For the purposes of this 

registration review, therefore, EPA has not assumed that DCOIT has 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 http://www.epa.gov/pesticides/cumulative/.

4 Environmental Risk Assessment

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

species determination for DCOIT. An endangered species effect determination was not made in 

the previous risk assessment for treated wood. 

Based on numerous uses of DCOIT, potential pathways of exposure to aquatic organisms include 

transport from in-service use to surface water by way of wastewater treatment plants (WWTPs), 

leaching from treated wood in terrestrial structures and subsequent runoff to surface water, and 

leaching from pressure-treated wood in aquatic environments. The risk assessment will also

allow the agency to determine whether each use of DCOIT 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.

Based on the antimicrobial uses of DCOIT with active products in Table 5, the agency has 

created conceptual models for potential routes of environmental exposure which are included in 

“Conceptual Models for Environmental Exposure Pathways of Antimicrobial Pesticides,” found 

in the docket at www.regulations.gov EPA-HQ-OPP-2014-0638-001. For the uses with active 

products, the relevant page numbers are 13-14 (cooling towers), 17 (adhesives and caulks), 15 

(plastics and rubber), 24-25 (non-antifoulant paints and varnish), 11 (antifoulant paint), and 29 

(wood preservation). All relevant routes of environmental exposure will be considered in the 

risk assessment. 

4.1 Environmental Fate Assessment

Even though there are potential pathways by which DCOIT can reach the aquatic environment, 

DCOIT degrades very rapidly in aquatic environments via various processes with half-lives of <

1 hour to 2.9 days. DCOIT is not readily biodegradable in a wastewater treatment plant 

(WWTP), as defined by the criteria of 70 % degradation in 28-days and 60 % in a 10-day period, 

but 80 % of DCOIT degraded in 28 days and 52 % of DCOIT did degrade in a 10-day period. 

Page 21 of 77
However, the degradates N-(n-octyl) malonamic acid and N-(n-octyl) acetamide were readily 

biodegradable in a WWTP. DCOIT that is used in paper mills and cooling towers can also 

reach aquatic environments since WWTP transit times are <1day. DCOIT that leaches out of 

products can be subsequently transported to surface water via runoff but would not be expected 

to persist in the terrestrial and aquatic environments based on its rapid potential to degrade by 

biotic processes. 

DCOIT (parent compound, 3(2H)-isothiazolone, 4,5-dichloro-2-octyl-) degrades by 

biodegradation and dechlorination to form the primary metabolites N-(n-octyl) malonamic acid, 

N-(n-octyl) oxamic acid, and N-(n-octyl) acetamide which are low-molecular weight nitrogenous 

carboxylic acid compounds. These degradates undergo demethylation and loss of CO2

(decarboxylation) to eventually form the terminal degradates, formic acid and CO2. The 

degradation rate of DCOIT is generally faster in biotic than abiotic conditions. 

4.1.1 Leaching (Wood/Antifoulant)

The agency has reviewed 19 antifoulant leaching studies (including 29 paints) in simulated 

seawater which demonstrated an average leach rate of 20.4 ug/cm2

/day. In the antifoulant 

leaching studies, the leaching rates were highly variable and unrelated to DCOIT content. The 

agency has also received five wood leaching studies that demonstrate the potential for terrestrial 

exposure and aquatic exposure, of which two have been reviewed (multiple studies, see 

Appendix B for further details). The reviewed studies indicate an average leach rate of 1.9 

ug/cm2/day. The extent of exposure from DCOIT used to preserve wood will be addressed in 

registration review. 

4.1.2 Water and Sediment

DCOIT is soluble in water (14 ppm, Table 4) but is expected to preferentially partition to the 

sediment phase of the aqueous environment rather than to water and air. DCOIT has a Henry’s 

Law constant of 1.2 x 10-7 atm m3 mol-1 which indicates that partitioning to air from aqueous 

media is not a significant route of dissipation (Table 4).2

 Sorption to soil and sediment increases 

as the soil and sediment organic carbon (OC) content increases, and will move from soil into 

water in low OC environments. Parent DCOIT did not bioconcentrate in fish to a significant 

degree, but the straight-chain polar metabolites were the primary residue in bluegill sunfish. 

DCOIT biotic degradation studies demonstrated the formation and decline of degradates to form 

straight chain, nitrogenous carboxylic acid degradates, formic acid, and CO2. The half-lives in 

aquatic studies (representing surface water) were <1 hour to 2.9 days in fresh- and saltwater 

systems, and these aquatic metabolism half-lives are relatively consistent with the hydrolysis 

half-lives of 3.5 days at pH 9. Most of the aquatic metabolism study systems (water only or 

water: sediment) had a pH range of 7 to 8, and sorption accounts for a large percentage of the 

rapid dissipation when sediment was used. Table 10 below contains additional information on 

the water and sediment dissipation of DCOIT and its degradates.

2 Henry’s Law values are calculated using the equation [VP (mm Hg) * molecular weight (grams/mol)]/[760 * water 

solubility (mg/l)].

Page 22 of 77

 
Table 10 - Summary of Environmental Fate Data for DCOIT in Water and Sediment

Test Guideline 

(parent compound 

unless stated)

Study Result (halflives)3Significant Degradation 

Products4

Reference 

(MRID)

Hydrolysis pH 4 (260 days) 

pH 7 (71 days)

pH 9 (3.5 days)

DCOIT sulfinic acid 

Propiolic acid amine

46780744

Photodegradation in 

water

17.2 days N-(n-octyl) oxamic acid 

N-(n-octyl malonamic acid)

41845001

Anaerobic Aquatic 

Metabolism

<1 hour N-(n-octyl) malonamic acid 

N-(n-octyl) oxamic acid

41845002

42341101

0.33 day (8 hours) No significant degradates 46816306

Aerobic Aquatic 

metabolism

0.04 days (<1 hour) N-(n-octyl) malonamic acid 

and N-(n-octyl) oxamic acid

41845003

42341102

42772802

2.9 days (67 hours) 2-(n-octyl) carbamoyl-2-

chloroethylene sulfonic acid 

N-(n-octyl) oxamic acid

46816307

0.86 day (21 hour) None 46816306

Adsorption/Desorption Kd values of 14-76 L/kg 

(0.2-4.4 % OC) and 625-

905 L/kg (4.1-5 % OC)

Koc values of 1,691-

7,865 L/kg (0.2-4.4 % 

OC) and 15,441-18,100

L/kg (4.1-5 % OC)

Not applicable 41845004

164668

Mobile to hardly 

mobile in soil 

based on Koc 

values and FAO 

classification.5

Bioaccumulation study 

in fish

(BCFs, % depuration)

Edible (660X, 77)

Non-edible (200X, 78),

Whole fish (660X, 60)

Polar metabolites (straightchain degradates) were highest 

residues in fish

164507

164508

41845006

4.1.3 WWTP

Studies on degradation, sorption, and toxicity to wastewater organisms for DCOIT have been 

submitted. As a result of these studies, the agency expects sorption of DCOIT to sludge with a 

Kd of 2,566 L/kg resulting in limited outflow of DCOIT and its N-(n-octyl) malonamic and N-

(n-octyl) acetamide degradates to surface water from a WWTP (MRID 46780735). The extent 

of toxicity to WWTP organisms is uncertain. DCOIT is not readily biodegradable but the 

3 Adsorption/desorption and bioaccumulation in fish studies represent partitioning and not half-lives. 4 Significant degradates formed at >10 % of applied parent compound. 5 http://www.fao.org/docrep/003/x2570e/x2570e06.htm.

Page 23 of 77

 
degradates N-(n-octyl) malonamic acid and N-(n-octyl) acetatamide were readily biodegradable 

(MRIDs 46780741 and 46780742). The submitted ASRI study (MRID 46816305) was not tested 

at an adequate concentration and must be repeated because the registrant did not establish an 

IC50. This is an anticipated data need. 

4.1.4 Water Quality

DCOIT and its degradates are not identified as a cause of impairment for any water bodies listed 

as impaired under section 303(d) of the Clean Water Act.

6 In addition, no Total Maximum Daily 

Loads (TMDL) have been developed for DCOIT.

7 More information on impaired water bodies 

and TMDLs can be found at EPA’s website.

8

4.2 Ecological Effects Assessment

The agency has a complete data set for DCOIT and will be able to conduct a risk assessment on 

the current uses of this chemical. However, since DCOIT is used as a wood preservative, risk to 

honeybees from wood treated with DCOIT will need to be assessed. A honeybee study is 

included as an anticipated data need for use in a risk assessment on the wood preservative uses of 

this chemical (850.3020: honeybee, acute contact). 

4.2.1 Mechanism of Action

The specific mechanisms by which DCOIT inactivates or kills wood rotting organisms in not 

known. It most likely disrupts the internal mechanisms of the target organism.

4.2.2 Measures of Effect (Ecotoxicology Endpoints)

Ecotoxicity endpoint data are used as measures of effects to aquatic and terrestrial organisms. 

All available ecotoxicity endpoints in the agency’s files from DCOIT studies submitted by 

registrants or other interested parties, federal laboratory data, or from the public literature are 

tabulated in Appendix C along with the data requirements and data gaps. The most sensitive 

values for each receptor group are used for the risk assessment. Table 11 contains the ecological 

endpoints for use in risk assessment. These selected endpoints will be updated during the risk 

assessment phase based on any additional submitted data or data found in the public literature.

Table 11– Ecological Effects Endpoints Selected for Assessing Risks from DCOIT Use

Receptor 

Group Surrogate Species Risk Scenario Toxicity Endpoint Reference

Freshwater fish

Bluegill Sunfish Acute 96-h LC50 = 1.4 ug/L MRID# 

41465801

Rainbow Trout Chronic NOAEC = 0.56 ug/L MRID# 

45865201

Freshwater 

invertebrates Daphnia magna Acute 48-h EC50 = 9,7 ug/L MRID# 47802222

6 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885. 7

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

group_name=PESTICIDES. 8 http://www.epa.gov/owow/tmdl/.

Page 24 of 77

 
Receptor 

Group Surrogate Species Risk Scenario Toxicity Endpoint Reference

Chronic NOAEC = 0.627 ug/L MRID# 

45153101

Freshwater benthic 

invertebrates Freshwater midge Subchronic/Chronic

 10-day LC50 = 13 mg/kg

 NOAEC = 4.9 mg/kg

MRID# 

468516304

Estuarine/marine fish Sheepshead minnow Acute 96-h LC50 = 20.5 ug/L MRID# 

41741502

Chronic Not requiredA --

Estuarine/marine 

invertebrates

Mollusk Acute 48-hr EC50 = 24 ug/L MRID# 

41756801

Shrimp Acute 96-hr LC50 = 4.7 ug/L MRID# 

41741503

Chronic Not requiredA --

Estuarine/marine 

benthic invertebrates Marine amphipod Subchronic/Chronic

10-day LC50 = 95.4 mg/kg

NOAEC = 64.8 mg/kg

MRID# 

46780740

Algae Green alga

Nonlisted 96-hr EC50 = 47 ug/L MRID# 

45862503

Listed NOAEC = 7.8 ug/L MRID# 

45862503

Aquatic vascular 

plants Duckweed

Nonlisted EC50 = 166 ug/L MRID# 

45865204

Listed NOAEC = 11.8 ug/L MRID# 

45865204

Seedling Emergence Red clover

Nonlisted EC25 = 8.4 mg/kg MRID# 

45870601

Listed NOAEC = 5 mg/kg MRID# 

45870601

Vegetative vigor Canola

Nonlisted EC25 = 0.94 mg/kg MRID# 

45905001

Listed NOAEC = 0.12 mg/kg MRID# 

45905001

Birds

Northern bobwhite 

quail Acute LD50 = 2002 mg/kg MRID# 47802224

Mallard duck Subacute 

dietary

LC50 >4639 mg/kg MRID# 

42214902

Chronic Not requiredA --

Mammals

Acute NOAEL = 30 mg/kg/day MRID# 

43471604

Chronic NOAEL = 16 mg/kg/day MRID# 

45756501

Nontarget insects Honey bee Acute RequiredB --

A Not required for this use pattern.

B Required for this chemical because it is used as a wood preservative. 

4.3 Exposure Analysis Plan

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates

Available OPP models will be used to determine the estimated environmental concentration 

(EECs) in the aquatic environment. Resulting exposure estimates will be compared to the 

toxicity endpoints to determine if levels of concern are exceeded for each receptor group. 

Page 25 of 77
4.3.2 Screening Level Down-the-Drain Analysis

The Down-the-Drain (DtD) module of E-FAST (Exposure and Fate Assessment Screening Tool) 

was used to determine the potential for aquatic organisms downstream of domestic wastewater 

treatment plants that receive discharges from end-use of DCOIT to be exposed to DCOIT and its 

degradates. The results of the DtD module runs are expressed as number of days of exceedance 

of concentrations of concern (COC) for aquatic organisms. A detailed description of derivation 

of data for input parameters selected to run the DtD module and of the theoretical basis for this 

model is presented in Appendix E. A 77% removal was assumed for model runs based on an 

Activated Sludge Sorption Isotherm study (MRID 46780743). The model accounts for 

degradation and removal within the treatment facility, but since transit times through the facility 

are <1day, some DCOIT is expected to be release to the surface water.

The DtD analysis for DCOIT is intended to serve two purposes: (1) to demonstrate the 

maximum WWTP influent volume of DCOIT that would trigger potential concerns for aquatic 

organisms exposed to DCOIT downstream of domestic wastewater treatment plants and (2) to 

evaluate potential exposures based on the assumptions that the total production volume of 

DCOIT enters domestic wastewater treatment plants. A key purpose of the DtD analysis for 

DCOIT is to determine the lowest maximum annual WWTP influent volumes of DCOIT that 

would trigger potential concerns for aquatic organisms downstream of domestic WWTPs.

Table 12 presents results of a screening-level DtD analysis for DCOIT which, based on 

laboratory toxicity data for freshwater organisms, is highly toxic. Based on these aquatic toxicity 

data and the total annual production volume reported in the EPA Section Seven Tracking System 

(SSTS) of approximately 470,000 kilograms of DCOIT, the DtD model predicted exceedences of 

concentrations of concern for acute, chronic and endangered aquatic organisms. Both high end 

and average scenarios were run and the results are presented in the following table.

Table 12 - Results of a Screening Level Down-the-Drain Analysis for DCOIT

 

 High End Scenario

WWTP Influent 

Volume

Freshwater Fish Acute 

(COC = 0.7 ug/L)

Endangered Freshwater Fish Acute 

(COC = 0.07 ug/L)

Freshwater Fish Chronic 

(COC = 0.56 ug/L)

470000

kilograms/year Exceeded 154 days per year Exceeded 327 days per year

Exceeded 175 days per 

year

WWTP Influent 

Volume

Freshwater Invertebrates 

Acute (COC = 4.85 ug/L)

Endangered Freshwater Invertebrates 

Acute (COC = 0.485 ug/L)

Freshwater Invertebrates 

Chronic (COC = 0.624

ug/L)

470000 

kilograms/year Exceeded 19 days per year Exceeded 189 days per year

Exceeded 166 days per 

year

 

 Average –Case Scenario

Page 26 of 77
WWTP Influent 

Volume

Freshwater Fish Acute 

(COC = 0.7 ug/L)

Endangered Freshwater Fish Acute 

(COC = 0.07 ug/L)

Freshwater Fish Chronic 

(COC = 0.56 ug/L)

470000

kilograms/year Exceeded 19 days per year Exceeded 77 days per year Exceeded 23 days per year

WWTP Influent 

Volume

Freshwater Invertebrates 

Acute (COC = 4.85 ug/L)

Endangered Freshwater Invertebrates 

Acute (COC = 0.485 ug/L)

Freshwater Invertebrates 

Chronic (COC = 0.624

ug/L)

470000 

kilograms/year Exceeded 2 days per year Exceeded 25 days per year Exceeded 21 days per year

This screening level analysis assumes that all DCOIT used in a year may be released to domestic 

wastewater treatment plants. Based on registered uses of DCOIT presented in Table 5 of this 

FWP, there are some uses, such as commercial and industrial cooling water systems and paper 

mill water systems, for which discharges may enter industrial WWTPs rather than domestic 

WWTPs prior to entering surface water. Different methods and tools for assessing potential 

exposures and associated ecological risks will be applied for these other types of uses.

Information on the various uses of DCOIT will reduce the uncertainty regarding the amount of 

DCOIT that would be expected to enter domestic versus industrial WWTP and will allow the 

agency to refine the risk assessment. The agency does not have high quality data on the toxicity 

of DCOIT to activated sludge microorganisms in wastewater treatment plants. Consequently, 

the Agency anticipates the need to require data on Activated Sludge Respiration Inhibition 

(OECD 209) or Modified Activated Sludge Respiration Inhibition (OCSPP 850.6800).

4.4 Effects Analysis Plan

Additional open literature studies will be identified through EPA’s ECOTOXicology (ECOTOX) 

database. The ECOTOX database will be searched during the risk assessment phase of DCOIT

and the data reviewed following the agency’s policy for reviewing public literature for use in

assessing risks from pesticides.

9

 Those ecotoxicity values found in the public literature to be 

more sensitive than those currently in the database of submitted guideline studies or which 

satisfy existing data gap(s) will be used during the risk assessment phase of DCOIT. ECOTOX 

was created and is maintained by the USEPA, Office of Research and Development, and the 

National Health and Environmental Effects Research Laboratory's Mid-Continent Ecology 

Division.

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, 

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 

10http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_wor 

kgroup/esa_evaluation_open_literature.htm.

Page 27 of 77

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

taxonomic groups. As part of its reregistration decision for DCOIT, 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), DCOIT 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, 201310 and includes some pesticides 

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

construed as a list of known or likely endocrine disruptors.

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

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

website.11

6 Optional Label Changes

The agency invites any label amendments that could be considered to eliminate the anticipated 

need for EPA to require certain data, reduce the possibility that EPA’s planned risk assessments 

overestimate risk due to reliance on conservative assumptions, and/or improve label clarity. For 

DCOIT, it is recommended that all labels and uses be clarified as to whether or not they are 

intended for food or nonfood contact. Additionally as noted in Sections 1.5.1 and 3.2, there are 

uses on technical labels that may result in potential dietary exposure (materials preservatives in 

cleaning solutions and in-container preservatives), but there are not corresponding uses on enduse products. Registrants of products EPA Reg Nos 707-224 and 6701-58 are encouraged to 

remove the uses from the technical label or provide the appropriate application rate and 

directions for use on the EUP labels through an amendment. 

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

chemicals. 11 http://www.epa.gov/endo/

Page 28 of 77

 
7 Next Steps

After the FWP for the DCOIT case is posted to the docket at EPA-HQ-OPP-2014-0403, a Data 

Call In (DCI) is anticipated to be issued a year later.

Page 29 of 77
8 References 

Product Chemistry Citations

MRID 40808501. Chang, S. (1987) Product Chemistry RH-25,287 Technical: Project ID NAL88-002. Unpublished study prepared by Rohm and Haas Co. 106 p.

MRID 41361601. Chang, S. (1987) Product Chemistry: RH-25,287 Technical: Lab Project 

Number: NAL-88-002. Unpublished study prepared by Rohm & Haas Co. 98 p.

Agency Citations

U.S. Environmental Protection Agency (EPA). 2002. ECOTOX User Guide: ECOTOXicology 

Database System. Version 3.0. Available: http://www.epa.gov/ecotox/.

Mostaghimi, Siroos. August 13, 2007. Estimated Environmental Concentrations Reported by 

Registrant for Kathon 287 WT Wood Preservative. D330125. 

U.S. Environmental Protection Agency. High Production Volume Information System (HPVIS). 

http://www.epa.gov/hpvis/. 

Page 30 of 77
Appendix A Toxicology Profile

Acute Toxicity for Product Labeling 

As summarized in Table A1, acute toxicity data show that 1,2-benzisothiazolin-3-one (DCOIT) 

is moderately toxic by the oral route (Toxicity Category III ); however, because the irritation and 

corrosivity of the chemical, the acute dermal, acute inhalation, primary eye irritation and primary 

skin irritation studies for the technical material are waived (Toxicity category I). DCOIT is a 

dermal sensitizer. 

Table A1 – Acute Toxicity Studies for DCOIT

Guideline

Number Study Type MRIDNumbers Results Toxicity Category

870.1100 Acute Oral 42977701 LD50=1636 mg/kg III

870.1200 Acute Dermal N/A waiver for technical 

material 

I

870.1300 Acute Inhalation 43471602 LC50 not determined 

(Corrosive) 

I

870.2400 Primary Eye Irritation N/A waiver for technical 

material

I

870.2500 Primary Skin Irritation N/A waiver for technical 

material

I

870.2600 Dermal Sensitization 47004002; 

48748511

Sensitizer N/A

Page 31 of 77
Subchronic Toxicity 

There are three subchronic studies: one 90-day rat oral study (MRID 43471603), one 90-day dog 

oral study (MRID 45747201), and one 90-day rat inhalation study (MRID 43487501). 

90-day rat oral toxicity study (MRID 43471603)

In the subchronic rat oral study, oral administration of DCOIT Technical via the diet to 

Crl:CDBR rats[10/sex/group for 13 weeks at dose levels of 0, 100 ppm [6.2 males/7.2 females 

mg/kg/day], 500 ppm [32.5 males/36.7 females mg/kg/day], 1000 ppm [60.7 males/74.7 females 

mg/kg/day], and 4000 ppm [248.2 males/278.4 females mg/kg/day ] resulted in decreased body 

weight throughout the study at the high dose level in both sexes [males 86%/ females 80% of 

control at 13 weeks], decreased overall body-weight gain [males 79%/ females 77% (4000 ppm) 

females 85% (1000 ppm) of control], decreased food consumption at 4000 ppm for both sexes 

and at 1000 ppm in females initially, decreased water consumption 4000 ppm, changes in several 

hematology/blood chemistry parameters consistent with chronic, low level blood loss, and 

microscopic, treatment related, changes in the forestomach [increase in mucosal 

erosion/ulceration, submucosal edema, acute inflammation, hyperplasia of the mucosal 

epithelium, and/or hyperkeratosis). The NOAEL is at 500 ppm [32.5 males/36.7 females 

rug/kg/day], the LOAEL at 1000 ppm [60.7 males / 74.7females mg/kg/day], based on 

microscopic lesions in the forestomach in males and decreased body weight/gain and food 

consumption, decreased serum triglyceride levels, and microscopic lesions in the 

forestomach in females. This 90-day oral toxicity study in the rat is Acceptable/Guideline and 

satisfies the guideline requirement for a 90-day oral toxicity study (OPPTS 870.3100; OECD 

408) in rats.

90-day dog oral toxicity study (MRID 45747201)

In the subchronic dog oral toxicity study 45747201), DCOIT [98.42 a.i.] was administered to 

beagles (4/sex/dose) in the diet at dose levels of approximately 0, 100, 300 and 1500 ppm for 13 

weeks. No treatment-related effects were observed on survival, clinical or neurobehavioral 

findings, ophthalmology, physical examinations, organ weights or macroscopic pathology in 

either sex at ≤ 1500 ppm. Some microscopic effects were considered to be secondary and caused 

by decreased body weight and food consumption (thymic atrophy).

One 1500 ppm female beagle exhibited severe morbidity due to complications with the feeding 

regimen, morbidity was not associated with treatment with the test material. There were no 

changes in mean body weight gain and mean food consumption for Groups 1-3 for both sexes. 

Administration of 1500 ppm resulted in decreased mean body weight gain for both males and 

females over the length of treatment, compared to controls. The decrease in body weight was 

correlated with reductions in mean food consumption for these animals.

Several changes were observed in hematology parameters including substantial decreases in 

erythrocyte count (20 decrease at week 7; 14% decrease at week 13), hemoglobin (21% decrease 

at week 7; 15% decrease at week 13), reticulocyte count (61% decrease at week 7; 39% decrease 

at week 13), and hematocrit values (20% decrease at week 7; 11% decrease at week 13) in 1500 

ppm males. Statistical significance was only reached at Week 7 for erythrocyte count, 

hemoglobin and hematocrit. Platelet counts were elevated in both males and females at Week 7 

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(22 and 26%, respectively) and Week 13 (47 and 43%, respectively), but only reached statistical 

significance in males at Week 7. Several changes in clinical chemistry parameters also were 

noted in 1500 ppm animals. Total protein, albumin, and hemoglobin were reduced in 1500 ppm 

males (Week 7 and 13), and total protein and globulin were reduced in 1500 ppm females 

(Weeks 7 and 13). Statistical significance was reached in males at Week 7 for total protein and 

albumin at Week 13 in females. It is likely that these changes were a result of the decreased body 

weights observed in these animals. A decreased was seen in the absolute thymus weight in both 

1500 ppm males and females. The decrease in thymus organ weight was supported by both 

macroscopic and microscopic findings. At the 1500 ppm dose level, the thymus gland was 

reported as small in %males and 2/4 females, ranging from mild to severe. Consistent with 

necropsy findings, a marked diffuse atrophy of the cortical and medullary lymphoid areas of the 

thymus were observed in the 1500 ppm females was secondary to the decreased body weight and 

food consumption observed. A NOAEL of 300 ppm (10.2 mg/kg/day in males, 10.1 

mg/kg/day in females) is indicated. The LOAEL is based on decreased body weight and 

food consumption, hematologic and clinical chemistry parameter changes observed at 1500 

ppm (47.5 mg/kg/day in males and 25.9 mg/kg/day in females). This 90-day oral toxicity 

study in the dog is Acceptable/Guideline and satisfies the guideline requirement for a 90-day 

oral toxicity study (OPPTS 870.3150; OECD 409) in non-rodent species.

90-day rat inhalation study (MRID 43487501)

In this subchronic rat inhalation study, groups of 32 male and 32 female Crl;CD BR rats received 

nose-only inhalation exposure for 6 hours per day, 5 days per week, for thirteen weeks to air, an 

aerosol of o-xylene (the vehicle) at 238.5 mg/m3

, or DCOIT at concentrations of 0.02, 0.63, and 

6.72 mg/m3

. At the end of the thirteen week exposure period, half of the animals in each group 

were necropsied, 5 from each group were necropsied at six months, and the remaining animals 

were necropsied at the end of a one-year recovery period. Mean mass median aerodynamic 

diameter of DCOIT was 1.4 μm, and the mean geometric standard deviation was 4.6, with 72% 

respirable fraction. Increased mortality was observed in the vehicle control group of female rats 

during the exposure period, but was attributed to over-restraint in the nose-only tubes. There 

was no other treatment-related increase in mortality either during the treatment period or during 

the recovery period. The incidence of rales was increased in high dose males and females 

beginning at weeks 2-3 of exposure. Significant differences were observed in body weight gain 

between the air control and vehicle control group during treatment, indicating an effect of 

vehicle on body weight gain. When compared with the vehicle control, the test material resulted 

in decreased body weight gain of approximately 20% at the high dose level beginning at week 2 

and persisting throughout the thirteen week exposure period for male and female rats. During 

recovery, there were no significant effects on body weight gain in treated male or female rats. 

No statistically significant differences were observed in treated rats vs. vehicle or control rats in 

clinical chemistry or hematology parameters at any dose tested. Treatment-related microscopic 

lesions in the nose, larynx, and lungs were observed in mid- and high-dose treated rats. Minimal 

or mild subacute inflammation of the nose was observed in increased incidence, as was 

transitional respiratory epithelial hyperplasia and goblet cell hyperplasia. In the epiglottis, 

hyperplasia of the squamous and cuboidal epithelium was observed in mid- and high dose rats, as 

was chronic-active inflammation of the epiglottis. Goblet cell hyperplasia and acute 

inflammation was observed in increased incidence in the lungs of high dose rats. Based upon 

the histopathological alterations observed in the nose, larynx, and lungs, the systemic 

Page 33 of 77
LOAEL is determined to be 0.63 mg/m3, and the systemic NOAEL is determined to be 0.02 

mg/m3. This 90-day subchronic inhalation study in the rat is Acceptable/Guideline and

satisfies the guideline requirement for a subchronic inhalation toxicity study (OPPTS 870.3465) 

in the rat.

Developmental Toxicity 

There are two developmental toxicity studies available in assessing the developmental effects of 

DCOIT: one rabbit developmental study which was considered unacceptable to be used in risk 

assessment and one acceptable rat developmental study.

1) Rabbit Developmental Toxicity Study (MRID 47802217)

In the developmental toxicity study (MRID 47802217), DCOIT (97.1% a.i.; Batch # 156732) 

was administered in the diet to 24 time-mated New Zealand White (CRL:KBL[NZW]) 

rabbits/group at dose levels of 0, 125, 500, or 2000 ppm (equivalent to 0, 5, 20, or 59 mg/kg/day) 

from gestation day (GD) 6 through 28. All surviving does were killed on GD 28; their fetuses 

were removed by cesarean section and examined.

There were no effects of treatment on mortality, clinical signs, gravid uterus weight, or gross 

pathology. One 2000 ppm doe (#88) was found dead on GD 28, and was found to have dark red 

discoloration of the forestomach and a rupture of the peritoneum at necropsy. This death was 

considered incidental. At 2000 ppm, a body weight loss (-76 g) was observed during GD 6-9, 

and cumulative body weight gains (expressed as% relative to GO 6) were decreased from GD 9 

through GD 28. These findings were associated with decreased mean absolute (g/animal/day) 

and relative (g/kg BW/day) food consumption (deer. 17-58%) during GO 6-19, resulting in an 

overall (GD 0-28) decrease of 19%. However, the magnitude of the decreases diminished with 

time. Therefore, the decreased food consumption is considered to be a result of decreased 

palatability of the diet, and not a manifestation of systemic toxicity. The maternal LOAEL was 

not observed. The maternal NOAEL is 2000 ppm (equivalent to 59 mg/kg/day). 

There were no treatment-related abortions, premature deliveries, or complete litter resorptions. 

No effects of treatment were observed on corpora luteal doe, implantations/doe, live fetuses/doe, 

resorptions/doe (early, late, or complete litter), sex ratio, post-implantation loss, or fetal or 

placental weight. There were no treatment-related external, visceral, or skeletal malformations or 

variations. The developmental LOAEL was not observed. The developmental NOAEL is 2000 

ppm (equivalent to 59 mg/kg/day).

This study is classified Unacceptable - Guideline and does not satisfy the guideline requirements 

(OPPTS 870.3700b; OECD 414) for a developmental toxicity study in the rabbit because, the test 

compound was administered via the diet as opposed to the normal method of administration (oral 

gavage). As palatability affected maternal health at 2000 ppm due to reduced food consumption, 

higher dietary concentrations would not have been appropriate. The rabbit developmental 

toxicity study is an anticipated data need. 

2) Rat Developmental Toxicity Study (MRID 43471604)

In a developmental toxicity study in rats (MRID # 43471604), groups of pregnant female CD rats 

(25/dose) were administered DCOIT (98.8% purity) by gavage at dose levels of 0, 10, 30, and 

Page 34 of 77
100 mg/kg/day on gestation days 6 through 15. At 100 mg/kg/day, clinical signs of toxicity were 

observed in maternal animals, consisting of scant feces, soft feces, and/or diarrhea. One dam died 

at the 100 mg/kg/day dose level. Decreased body weight gain was observed at 100 mg/kg/day 

(73% of control in pregnant dams). There were no significant differences in the number of 

corpora lutea/dam, implantations/dam, live fetuses/dam, resorptions/dam, or in pre- or postimplantation losses, litter weight, or fetal body weight. There were no fetal external variations or 

developmental retardations, and there were no fetal soft tissue developmental retardations. 

Fetuses at the high dose showed an increase in the number of fetuses with wavy ribs, along with 

an increase in number of litters with this effect as well as the severity of the effect. The 

Maternal NOAEL is determined to be 10 mg/kg/day, based on decreased food consumption 

during dosing and clinical signs at 30 mg/kg/day. The Developmental NOAEL is 

determined to be 30 mg/kg/day, based on increased litters with wavy ribs at 100 mg/kg/day. 

The study is classified Acceptable/Guideline and satisfies the guideline requirement for a 

prenatal developmental toxicity study (OPPTS 870.3700) in the rat.

Reproductive Toxicity

There is one two-generation reproduction study (MRID 457565-01). In the study, DCOIT 

(100.3% a.i.) was administered via diet to male and female Crl:CD®BR rats at dose levels of 0, 

200, 800, or 3200 ppm (equivalent to 0, 16-20, 62-88, and 235 mg/kg/day in males during 

premating and 0, 18-21, 67-93, and 259 mg/kg/day in females during premating). Significant 

offspring mortality at 3200 ppm caused an insufficient number of pups available to produce a 

second generation; consequently, all surviving 3200-ppm offspring were euthanized prior to 

sexual maturation. An additional treatment group of 400 ppm (equivalent to 30-39 mg/kg/day in 

males during premating and 33-41 mg/kg/day in females during premating) and a concurrent 

control group were initiated. P1 and P2 males and females were 6 or 3 weeks of age, 

respectively, when dosing was initiated and were exposed to the test article for at least 10 weeks 

prior to mating. Treatment continued until termination and included gestation and lactation 

periods. 

There was clear evidence of parental effects in 800- and 3200-ppm animals including clinical 

signs of toxicity (paleness), significantly decreased body weights (3200-ppm P1 and 800-ppm P2 

animals), significantly decreased body weight gain (3200-ppm P1 and 800-ppm P2 animals), 

significantly decreased body weight and body weight gain in 3200-ppm P1 females during 

gestation, significantly decreased body weight in 3200-ppm P1 females during lactation, and 

significantly decreased mean food consumption (3200-ppm P1 and 800-ppm P2 animals). 

Other findings included treatment-related hyperplasia and hyperkeratosis of the nonglandular 

stomach in 3200-ppm P1 males and females. Additionally, at 3200 ppm, an increased incidence 

of hypertrophy/vacuolation of the zona glomerulosa of the adrenal cortex was observed in both 

P1 males and females. Therefore, the NOAEL for parental toxicity is 400 ppm for males (30-

39 mg/kg/day) and females (33-41 mg/kg/day), while the LOAEL for parental toxicity is 800 

ppm (male: 62-88, femal: 67-93 mg/kg/ day) and is based on decreased body weight and 

body weight gain (and food consumption in the females). 

There was clear evidence of offspring effects in 800- and 3200-ppm animals including clinical 

signs of toxicity (paleness and distended abdomens in 3200-ppm F1 pups), significant decrease 

Page 35 of 77
in pup weight (800-ppm F1 and F2 animals and 3200-ppm F1 animals), significant gross 

necropsy findings (3200- and 800-ppm F1 pups), significant decreases in absolute and relative 

mean thymus (800 and 3200 ppm) and spleen (400, 800, and 3200 ppm) weights in F1 males, 

significant decreases in mean thymus weights (800 and 3200 ppm) in F1 females, and significant 

decreases in absolute and relative mean thymus weights (400 and 800 ppm) in F2 animals (both 

sexes). The mean age at preputial separation was delayed at 800 ppm and the mean age at 

vaginal opening delayed at 400 and 800 ppm. There was no treatment related effect on 

anogenital distance in the F2 offspring. 

Additionally, at 3200 ppm, the lactation index for P1 females was significantly decreased due to 

the significant increase in the number of litters with liveborn pups that did not survive to 

postnatal day (PND) 21. Concurrently, the number of pups dying, missing and/or cannibalized 

significantly increased on PND 5-21 and 0-21, contributing to the decreased lactation index. 

Therefore, the offspring toxicity NOAEL is 200 ppm (male: 16-20, female: 18-21 

mg/kg/day) and the offspring toxicity LOAEL is 400 ppm (male: 30-39, female: 33-41 

mg/kg/day) based on decreased absolute and relative spleen and thymus weight. 

This reproductive and fertility toxicity study in the rat is classified Acceptable/Guideline and

satisfies the guideline requirement [OPPTS 870.3800] for a Reproduction and Fertility 

Effects/Rat.

Immunotoxicity

There is currently no existing immunotoxicity study for DCOIT. This is a required study and has 

been identified as a data gap and an anticipated data need. The agency anticipates requiring this 

study.

Chronic toxicity/Carcinogenicity 

On December 6, 2007, the Health Effects Division's Hazard Science Policy Council (HASPOC) 

considered a request made by the registrant for waiver of a carcinogenicity study for DCOIT. 

This waiver request was made by the registrant on the basis of the available chemistry, 

metabolism and toxicology data for DCOIT. The HASPOC concluded that there was a 

significant toxicology database of acceptable studies for DCOIT, including subchronic, 

metabolism, developmental, reproductive, and genotoxicity studies. The similarity in structure, 

function, and biocidal mode of action supports bridging of data across the isothiazolone biocide 

chemicals. The available toxicology data on DCOIT shows that it is not mutagenic and does not 

produce any significant systemic toxicity. Toxicity found from the available data in 

experimental animals shows the primary effects to be associated with the irritant properties of the 

chemical, that is, irritation at the site of contact depending on the route of exposure. There were 

also no biological indicators from the available toxicology data that show systemic lesion(s) 

indicative of precursor effects that may lead to tumor formation. Thus, a risk assessment based 

on the irritant effects of DCOIT (the most sensitive effect of the chemical) is likely to afford 

protection against other potential systemic effects including carcinogenicity. Therefore, the lack 

of a chronic bioassay for DCOIT would not likely impact the risk assessment for the chemical, 

and will not be needed for DCOIT. 

Page 36 of 77
Mutagenicity 

DCOIT was tested for gene mutations in bacteria (S. typhimurium and Escherichia coli WP2 

uvrA) and mammalian cells (Chinese hamster ovary, CHO cells at the HGPRT locus) and found 

to be negative up to cytotoxic concentrations. It was also negative for chromosome aberrations in 

CHO cells and micronucleus induction in mouse bone marrow up to a lethal dose. Based on 

these findings, there is not mutagenicity concern for DCOIT. The associated studies are listed 

below.

In Vitro Studies

Salmonella Gene Mutation Assay; MRID 47107006

In a reverse gene mutation assay in bacteria (MRID 47107006), strain WP2 uvrA of E. Coli was 

exposed to Octhilinone, (46.2% a.i.; Lot #6110D015), SkaneTM M8 at concentrations of 1.5, 5, 

15, 50, 150, 500, or 1500 μg/plate in the presence and absence of mammalian metabolic 

activation in the plate incorporation procedure. Mammalian metabolic activation was derived 

from the livers of Aroclor 1254-induced Sprague-Dawley rats. These doses were selected based 

on a range-finding assay in which SkaneTM M8 was tested up to toxic concentrations (0.15-5000 

μg/plate, ±S9).

SkaneTM M8 was tested up to toxic concentrations. In the range-finding assay, SkaneTM M8 (2-

n-octyl-4-isothiazolin-3-one) was found to be toxic at ≥150 or 500 μg /plate. In the mutagenicity 

assays, the test article induced a reduction in the growth of the bacterial background lawn at 

≥150 μg/plate, ±S9. There were no significant increases in the frequency of revertant colonies as 

compared to the corresponding solvent control at any dose level in any condition. Toxicity was 

observed at the high doses (1500 μg/plate) in both the assays; hence the test material was tested 

up to the toxic limit. The positive controls induced the appropriate responses. There was no 

evidence of induced mutant colonies over background under the conditions of the assays.

This study is classified as Acceptable - Non-Guideline and does not satisfy the guideline 

requirement for Test Guideline OPPTS 870.5100; OECD 471 for in vitro mutagenicity (bacterial 

reverse gene mutation) data. Five or more strains were not used as required in the guidelines. The 

data for this one strain, however, is still valid.

Salmonella Gene Mutation Assay; MRID 43471605 

In two independent microbial gene mutation assays, Salmonella strains TA1535, TA1537, TA98, 

TA100 were exposed to non-activated doses of 0.3, 1, 3, 10, 30 ug/plate (initial trial) or 0.1, 0.3, 

1, 3 or 7.5 ug/plate (confirmatory trial) or S9 – activated doses of 3,10, 30, 100 or 300 ug/plate 

(initial trail) or 1, 3, 7.5, 30, or 75 ug/plate (confirmatory trial) of RH-287 technical. Cytotoxicity 

was achieved at levels of >3 ug/plate –S9 and >75 ug/plate +S9. There was no evidence of a 

mutagenic response at any dose either in the absence or presence of S9 in either trial. All strains 

responded in the expected manner to the corresponding nonactivated and S9-activated positive 

controls. The study is classified as Acceptable -Guideline and satisfies the requirement for a 

microbial gene mutation assay.

Page 37 of 77
Gene Mutation in Cultured Mammalian Cells (Chinese Hamster Ovary CHO Cells); 

MRID 43471606 

In two independent Chinese hamster ovary (CHO) in vitro gene mutation assays (MRID No. 

43471606), cell cultures were exposed to non-activated concentrations of 0.005, 0.025, 0.05, 

0.1, or 0.5 ug/ml (initial trail) or 0.025, 0.05, 0.1, 0.2, 0.4, 0.5 or 0.75 ug/ml (confirmatory trail) 

or S9-activated doses of 0.5, 1.0, 2.5, 5.0, 10 or 25 ug/ml (initial trail) or 2.5, 5.0, 6.0, 8.0 9.0, 10 

or 15 ug/ml (confirmatory trail). The S9 fraction was derived from Aroclor 1254-induced rat 

liver and the test material was delivered to the test system in acetone. 

In both trails, cytotoxicity was achieved at levels >0.5 ug/ml -S9 and >10 ug/ml +S9. There was, 

however, no evidence of a mutagenic response at any dose either with or without S9 or without 

S9 activation in either trail. CHO cells responded in the expected manner to the non-activated 

and S9-activated positive controls. 

The study is classified as Acceptable – Guideline and satisfies the requirements for Gene 

Mutation in Cultured Mammalian Cells (Chinese Hamster Ovary CHO Cells).

In Vitro Mammalian Cytogenetics Chromosome Aberration in Chinese Hamster Ovary 

Cells ; MRID 43471607 

In two independent Chinese hamster ovary in vitro cytogenetic assays (MRID 43471607) cell 

cultures were exposed to non-activated doses of 0.3, 0.6, or 0.7 ug/ml (initial trail) or 0.5, 0.6 or 

0.7 ug/ml (confirmatory trail) or S9 –activated concentrations of 6.0, 7.0, or 8.0 ug/ml (both 

trails). Cell harvest times were 23 hours (initial non-activated trail), 23 and 47 hours 

(confirmatory non-activated trial), 20 hours (initial S9 activated trail), or 20 and 44 hours 

(confirmatory S9-activated trail). The S9 fraction was derived from Aroclor 1254-indsuced rat 

livers and the test material was delivered to the test system in acetone.

Cytotoxicity, as indicated by reduced mitotic indices (app. 50%), was seen at > 0.7 ug/ml –S9 

and 8.0 ug/ml +S9; interference with cell-cycle kinetics was also observed at non-activated doses 

as low as 0.05 ug/ml and at S9-activated levels of >4.0 ug/ml. Slight increases in the frequency 

of cells bearing structural aberrations, particularly complex aberrations, were noted in cultures 

harvested after prolonged recovery from exposure to the highest non-activated or S-9 activated 

dose. Complex structural aberrations were also never exceeded 3% of the examined population 

and never approached a level of statistical significance. The evidence is, therefore, not sufficient 

to conclude that RH-287, tested up to cytotoxic levels, induced clastogenic response in the 

presence or absence of S9 activation. This study is classified Acceptable/Guideline.

In Vivo Studies

In Vivo Mammalian Cytogenetics - Erythrocyte Micronucleus Assay in Mice; MRID 

46790759

In a bone marrow micronucleus assay (MRID 46780759), fasted (3 hours prior to dosing), young 

adult CD-1 mice (5-9/sex/dose/harvest time) were treated once by gavage (10 mL/kg) with 

Kathon RH-287 (100.3% a.i., Lot # 0159F005) in corn oil at doses of 0, 60, 300, or 600 mg/kg. 

Bone marrow cells were harvested at 24 or 48 post-dosing.

Page 38 of 77
Mortality was observed in one 600 mg/kg female. Clinical signs of toxicity including diarrhea, 

anogenital staining, soft or scant feces, passiveness, and ataxia were observed in both sexes at 

600 mg/kg. A significant (p<0.05) decrease in PCE/NCE ratio was observed in both sexes at 

600 mg/kg at 48 hours post-dosing, indicating that Kathon RH-287 was toxic to the bone 

marrow.

No treatment-related increases in the MPCE frequency were observed in any treatment group at 

any sacrifice time when compared to controls. The positive control induced the appropriate 

response.

This study is classified as Acceptable-Non-Guideline and satisfies the guideline requirement for 

Test Guideline (OPPTS 870.5395; OECD 474) for in vivo cytogenetic mutagenicity data.

In Vivo Micronucleus Assay in CD1 mice; MRID 43471608 

In an in vivo micronucleus assay, groups of CD-1 mice (5,5 or 7/dose/sex/sacrifice time) 

received single oral gavage administrations of 32.5, 162.5, or 325 mg/kg RH-287 technical in 

corn oil. Bone marrow cells were examined 24 and 48 hours post-treatment for the frequency of 

polychromatic erythrocytes (MPEs). The observation of mild and transient clinical signs (passive 

behavior and scant feces in high dose males and females) suggests that the maximum tolerated 

dose (MTD) was not achieved. 

There was also no evidence of target cell cytotoxicity at any dose or harvest time. A slight but 

dose-related increase in MPEs was observed in male mice of the mid-and high dose groups at the 

24 hour sacrifice. The increase was significant at 325 mg/kg (p<0.05). However, the findings do 

not provide sufficient evidence to classify RH-287 as clastogenic/aneugenic in this test system.

Additional information submitted by the registrant to resolve the issue of the MTD led to the 

following conclusion by HED: “TBII has reached the decision that testing at higher dose levels 

would likely cause mortality. In light of this decision, we also agree that the significance increase 

in micronuclei seen in the high dose males was probably an anomalous finding since increases 

were not seen at 48 hours and were not observed in females at any dose or harvest time. We 

conclude that nothing further would be gained by repeating the micronucleus assay, RH-287 

technical is, therefore, considered to be negative in this in vivo system. The study is considered 

acceptable and satisfies the guideline requirement for a micronucleus assay.”

Other Toxicological Effects 

Dermal Absorption Factor Study: 

Dermal absorption of RH-287 was examined in male Crl:CD:BR rats (MRID # 43471610). 

There were six experimental groups of 4 rats each. Two concentrations of RH-287 were 

employed, 3% and 0.045%. Dermal application was made to a shaved 2 x 2 cm area on the 

interscapular region of the back, which was fitted with a contoured glass ring secured with 

cyanoacrylate glue and a porous top secured with rubber bands after application of the test 

substance in a dose aliquot of 60 μl. Two groups (A and B) received either 3% of 0.045% RH287 and urine and feces samples obtained at 10 hours post-dose, at which time the animals were 

killed and analysis for radioactivity performed in whole blood, plasma, and remaining carcass. 

Two additional (groups 9C and D) received either 3% or 0.045% RH-287 and were subjected to 

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the same procedures as groups A and B, except exposure duration was 24 hours. The last two 

groups (E and F) received either 3% or 0.045 % RH-287, and urine and feces samples taken at 0, 

10, 24, 48, and 72 hours post-dose. Animals in this group were sacrificed at 72 hours post-dose 

and analysis for radioactivity performed as for the other groups. Results of this study showed 

that at a dose of 0.045% RH-287, 44-50% of the dose was absorbed after a 10 hour exposure, 

and 70% after a 24 hour exposure. Administration of 3% RH-287 resulted in 31-34% absorption 

after 10 hours of exposure, and 52% absorption after 24 hours exposure. This study is 

Acceptable/Guideline and satisfies the guideline requirements (OPPTS 870.7600; OECD 427) 

for a dermal penetration study in rats.

Page 40 of 77
Appendix B Environmental Fate

Environmental Fate and Transport Properties of DCOIT and its 

Straight-Chain Degradates

This environmental fate assessment addresses the persistence and mobility of the parent 

compound 4,5 dichloro-2- n-octyl -4- isothiazolin -3- one (DCOIT) and the significant (>10 % 

of applied parent) straight-chain degradates which include N-(n-octyl) malonamic acid, N-(noctyl) oxamic acid, N-(n-octyl) acetamide, DCOIT sulfinic acid, propiolic acid amine, and 2-(Noctyl) carbamoyl-2-chloroethylene sulfonic acid. These straight chain degradates eventually 

degrade by biodegradation to acetic acid, formic acid and CO2. 

Based on the chemical and physical properties (Table 4) and environmental fate properties 

(Table B1) of DCOIT, DCOIT has limited water solubility, degrades more quickly at higher 

environmental pH values, and essentially stable to photodegradation in water by natural sunlight, 

and degrades with half-lives of up to 2 days in aerobic soil and <21 hours under aquatic 

conditions. Based on its vapor pressure of 4.5 x 10-6 mm Hg, its Henry’s Law constant of 1.2 x 

10-7

, and its rapid degradation with half-lives of <2 days, DCOIT is not expected to volatilize 

from water or soil. DCOIT is not expected to be mobile in soil and most residues were associated 

with sediment in the aquatic metabolism studies. Bioconcentration and subsequent depuration 

in fish can occur and the primary residues were polar straight-chain metabolites. In a wastewater 

treatment plant (WWTP), DCOIT was not readily biodegradable but the N-(n-octyl) malonamic 

and N-(n-octyl) oxamic acid degradates were readily biodegradable. Sorption to activated sludge 

is a significant route of dissipation. 

There is no record of review for the AWPA E11-06 accelerated leaching of wood preservatives 

in water (MRIDs 48414312 and 48424701) and AWPA E20-08 leachability of wood 

preservatives in soil contact (MRID 48236002) studies. These data will be reviewed during 

registration review.

Water and Sediment

Hydrolysis

The rate of hydrolytic degradation of DCOIT increases as the pH increases. At 25 oC, DCOIT 

degraded with calculated half-lives of 260, 71, and 3.5 days at pH 4, 7, and 9, respectively. The 

degradates included the straight-chain compounds DCOIT sulfinic acid and propiolic acid amine 

(MRID 46780744, OECD 111). 

Aqueous Photolysis

The registrant submitted two photodegradation in water studies for DCOIT. Using natural light 

at 25 oC, DCOIT photodegraded with a dark-control half-life of 17.2 days at 25 oC. The major 

degradates included N-(n-octyl) oxamic acid and N-(n-octyl) malonamic acid (combined 67 % of 

Page 41 of 77
parent) and minor degradate N-(n-octyl) acetamide reached 7.7 % of parent (MRID 41845001, 

OCSPP 835.2210). In a supplemental photodegradation in water study using natural sunlight, 

the registrant measured photodegradation degradates at 25 oC. In this study, the major degradate 

was N-(n-octyl) oxamic acid at 31 % of applied parent and the minor degradates were N-(noctyl) carbamic acid (5 %) and 4,6-dichloro thiazole (1.9 %) [MRID 42772801, OCSPP 

835.2210]. 

Octanol-Water Partition Coefficient

The octanol-water partition coefficient (log P or log Kow) is 2.8 (<3) [MRID 47802208], which 

indicates sorption to soil and sediment and potential bioconcentration in aquatic organisms can 

occur. This intermediate log P value is consistent with the extent of sorption and 

bioconcentration observed in the submitted and accepted studies.12 

Aerobic Aquatic Metabolism

DCOIT degraded in a under aerobic aquatic conditions with a half-life of <1 hour in a silt 

loam:seawater system at 25 oC. The only significant degradates were N-(n-octyl) malonamic 

acid, N-(n-octyl) oxamic acid, and N-(n-octyl) acetamide. Virtually all the residues were 

associated with sediment throughout the study (MRID 41845003, 4241102, 42772802, OCSPP 

835.4300). In an aerobic aquatic metabolism study conducted according to the OECD 308 test 

guideline, the half-life of DCOIT in a clay loam:pond water system was 0.86 days (21 hours) at 9 o

C. No significant degradates were formed in the study, and sediment residues accounted for 

virtually all radioactivity by 7-13 days (MRID 46816306). In an aquatic metabolisms study 

using only surface water with no sediment (OECD 309), the half-life was 2.9 days (67 hours) at 

18 oC. The significant degradates in the surface water study were 2-(N-octyl) carbamoyl-2-

chloro-ethylene sulfonic acid and N-(n-octyl) oxamic acid (MRID 46816307). 

Anaerobic Aquatic Metabolism

DCOIT degraded in a silt loam:seawater system under anaerobic aquatic conditions with a halflife of <1 hour. The degradates N-(n-octyl) malonamic acid and N-(n-octyl) oxamic acid were 

formed at significant concentrations in the study and declined to non-significant concentrations 

in the study. Sediment accounted for virtually all residues throughout the study (MRID 

41845002, OCSPP 835.4400). In another anaerobic aquatic metabolism study (OECD 308), the 

half-life in a clay loam:pond water system was 0.33 days (8 hours) at a temperature of 9 oC. No 

significant degradates were found in the study and sediment residues accounted for virtually all 

radioactivity by 7-14 days (MRID 46816306).

Bioconcentration in Fish

DCOIT bioconcentrated in bluegill sunfish with bioconcentration factors (BCF) values of 660X, 

200X, and 660X for edible, non-edible, and whole fish. A BCF is the ratio of the fish 

concentrations to the water concentrations. Depuration of 77, 78, and 60 % in edible, non-edible, 

12 MRIDs 41845004 and 2659908 for sorption and MRID 41845006 for bioconcentration in fish.

Page 42 of 77

 
and whole fish occurred by 21 days. Polar metabolites (straight-chain degradates) were highest 

residues in fish (MRID 41845006, OCSPP 850.1730).

Leaching from Treated Boat Paints and Wood

DCOIT will leach from treated boat paints and wood into soil and water and create 

environmental exposure. For boat paints, the agency has received and reviewed 19 ASTM 

D5108-90 studies containing leaching rates from 30 paints that contain DCOIT (See Table B3

for further details). The maximum, minimum, and average leaching rates in simulated seawater 

ranged from 5.2-100.6, 0-27.3, and 1.8-50.8 ug/cm2/day, respectively. The cumulative leaching 

rates ranged from 92-2,250 ug/cm2. The agency has also received five wood leaching studies 

that demonstrate the potential for terrestrial exposure and aquatic exposure, and only two have 

been reviewed (see Table B2 for more details). The extent of exposure from DCOIT used to 

preserve wood will be addressed in Registration Review. 

Soil

Soil Leaching/Adsorption/Desorption Batch Equilibrium

DCOIT is mobile to mobile to hardly mobile in soil and sediment, based on the Koc values from 

the submitted batch equilibrium studies (MRIDs 41845002 and 00164668).13 The Kd values 

were 31-76 L/kg in 4 soils with 0.4-1.35 % organic carbon (OC) and a Kd of 625 L/kg in a 

sediment with 4.1 % OC. The Koc values were 5,662-7,865 L/kg in 4 soils with 0.4-1.35 % OC 

and 15,441 L/kg in sediment with 4.1 % OC. Sorption was related to organic carbon content 

(r2=0.94) and pH (r2=0.71) [MRID 41845004]. In another study, the Kd values were 14-74 L/kg 

in 4 soils with 0.2-4.4 % organic carbon (OC) and a Kd of 905 L/kg in a sediment with 5 % OC. 

The Koc values were 1,691-6,850 L/kg in 4 soils with 0.2-4.4 % OC and 18,100 L/kg in a 

sediment with 5 % OC. Sorption was related to organic carbon content (r2

=0.46) [MRID 

00164668]. 

Aerobic Soil Metabolism

DCOIT degraded in aerobic silt loam and sandy soils with non-linear half-lives of 3.2 and 49 

hours, respectively. Significant (>10 % of applied) degradates were not formed in the study 

(MRID 44791101).

Anaerobic Soil Metabolism

Data on anaerobic soil metabolism (OCSPP 835.4200) were not submitted for DCOIT and were 

waived (MRID 46780763). However, the 835.4200 data requirement is satisfied with the results 

of the anaerobic aquatic metabolism studies with a DCOIT half-life of <8 hours (MRID 

41845002, OCSPP 835.4400; MRID 46816306, OECD 308).

13 http://www.fao.org/docrep/003/x2570e/x2570e06.htm.

Page 43 of 77

 
Carbon and Nitrogen Transformation Test (for soil microorganisms)

The IC50 of DCOIT was 393 mg/kg for carbon transformation (OECD 217) and the IC50 for 

nitrogen transformation was 155 mg/kg (OECD 216) [MRID 46780727]. Based on these results 

and the results of the metabolism studies (MRIDs 44791101, 41845002, 42341101, 41845003, 

42341102, 42778202, 46816306, 46316307) that demonstrate rapid degradation in soil and 

sediment, it is unlikely that DCOIT poses any risk to microorganisms in soil and sediment.

Fate and Transport in WWTP

Activated Sludge Sorption Isotherm

DCOIT was sorbed tightly to activated sludge with a Kd of 2,466 L/kg (MRID 46780735, 

OCSPP 835.1110). 

Ready Biodegradability

The registrant conducted three ready biodegradability studies (OECD 301B), one for parent 

DCOIT and two for the major degradates N-(n-octyl) malonamic acid and N-(n-octyl) acetamide. 

For a compound to be readily biodegradable, 70 % must degrade in the 28-day study and >60 % 

must degrade in a 10-day period.14 For DCOIT, 80 % degraded in the 28-day study and 52 % 

degraded in a 10-day period at 20-23 o

C (MRID 467800743). As a result, DCOIT is not

considered to be readily biodegradable. However, the degradates N-(n-octyl) malonamic acid 

and N-(n-octyl) acetamide were readily biodegradable. For N-(n-octyl) malonamic acid, 88 % 

degraded in the 28-day study and 65 % degraded in a 10-day period at 20-23 oC (MRID 

467800741). For N-(n-octyl) malonamic acid, 88 % degraded in the 28-day study and 65 % 

degraded in a 10-day period at 20-23 oC (MRID 467800741). ). For N-(n-octyl) acetamide, 89 

% degraded in the 28-day study and 65 % degraded in a 10-day period at 20-23 o

C (MRID 

467800742).

Activated Sludge Respiration Inhibition (ASRI)

The IC50 for DCOIT was >5.7 mg/l (ppm), which is less than the level of concern of 20 mg/l. 

At the reported water solubility of water in the ASRI study (5.7 ppm), 25 % inhibition of 

respiration occurred. However, the water solubility reported in MRID 40808501 was 14 ppm, 

and the submitted ASRI study (MRID 46780735) that was considered to be acceptable is now 

unacceptable and requires repeating. It is identified as an anticipated data need in Table 6. 

14 http://www.oecdilibrary.org/docserver/download/9730101e.pdf?expires=1398444902&id=id&accname=guest&checksum=83B700B

0ADDF5B296DA80F317FA501FF.

Page 44 of 77

 
Table B1. Status of Environmental Fate Data Requirements and Study Results

Test Guideline (parent 

compound unless stated)

OCSPP Guideline 

No. (unless 

specified)

Study Result 

(half-lives unless 

specified)

Significant 

Degradation 

Products15

Study status Reference (MRID) and 

Comments

Hydrolysis OECD 111 pH 4 (260 days) 

pH 7 (71 days)

pH 9 (3.5 days)

DCOIT sulfinic 

acid 

Propiolic acid 

amine

Acceptable 46780744

25 oC

Photodegradation in water 835.2240 15 and 116 days in 

irradiated and dark 

controls

Adjusted half-life 

of 17.2 days

N-(n-octyl) oxamic 

acid and N-(noctyl malonamic 

acid)

Acceptable 41845001

Natural sunlight

None reported 

(degradate 

identification study 

only)

N-(n-octyl) oxamic 

acid

Acceptable 42772801

Natural sunlight

25 o

C

Aerobic Soil Metabolism 835.4100 3.2 and 49 hours in 

silt loam and 

loamy sand 

No significant 

degradates

Acceptable 44791101

Anaerobic Soil Metabolism 835.4200 Waived Not applicable Waived 46780763

Anaerobic Aquatic 

Metabolism

835.4400 <1 hour N-(n-octyl) 

malonamic acid 

and N-(n-octyl) 

oxamic acid

Acceptable 41845002

42341101

Salt water:sediment system

pH 6.6 for sediment and pH 7.4 

for seawater

Sediment residues accounted for 

virtually all radioactivity in the 

study

15 Significant degradates formed at >10 % of applied parent compound.

Page 45 of 77

 
OECD 308 8 hours No significant 

degradates

Acceptable 46816306

Clay loam:water pond system

pH 8.1 for system

Sediment residues accounted for 

virtually all radioactivity by 7-14 

days

Aerobic Aquatic metabolism 835.4300 <1 hour N-(n-octyl) 

malonamic acid 

and N-(n-octyl) 

oxamic acid

Acceptable 41845003

42341102

42772802

Saltwater system

pH 6.6 for sediment and pH 7.4 

for seawater

25 o

C

Sediment residues accounted for 

virtually all residues throughout 

the study

OECD 309 2.9 days (67 

hours)

2-(n-octyl) 

carbamoyl-2-

chloroethylene 

sulfonic acid and 

N-(n-octyl) oxamic 

acid

Acceptable 46816307

Surface water only

pH 7.2

18 o

C

OECD 308 0.86 day (21 hour) None Acceptable 46816306

Clay loam:water pond system

pH 8.1 for system

9 o

C

Sediment residues accounted for 

virtually all radioactivity by 7-13 

days

Page 46 of 77
Adsorption/Desorption 835.1230 Kd values of 31-76 

L/kg (0.4-1.35 % 

OC) and 625 L/kg 

(4.1 % OC)

Koc values of 

5,662-7,865 L/kg 

(0.4-1.35 % OC) 

and 15,441 L/kg 

(4.1 % OC)

Not applicable Acceptable 41845004

Sorption related to organic carbon 

(OC) content (r2

=0.94) and pH 

(r2

=0.71)

Classified as mobile to hardly 

mobile in soil based on Koc 

values and FAO classification.16

835.1230 Kd values of 14-74 

L/kg in soils (OC 

of 0.2-4.4 %) and 

905 L/kg (5 % 

OC)

Koc values of 

1,691-6,850 L/kg 

(0.2-4.4 % OC) 

and 18,100 L/kg (5 

% OC)

Not applicable Supplemental 164668

Sorption related to organic carbon 

(OC) content (r2

=0.46)

Soil Column Leaching 835.1240 DCOIT was 31-47 

% of applied 

compound by 21 

days. 

80-100 % of total 

residues sorbed in 

top 6 inches of 

column

<1 % in leachates

Numerous 

degradates formed 

but not identified

Acceptable 41845005

16 http://www.fao.org/docrep/003/x2570e/x2570e06.htm.

Page 47 of 77

 
Bioaccumulation in fish 850.1730 BCFs of 660X, 

200X, and 660X 

for edible, nonedible, and whole 

fish

77, 78, and 60 % 

depuration in 

edible, non-edible, 

and whole fish by 

21 days

Polar metabolites 

(straight-chain 

degradates) were 

highest residues in 

fish

Supplemental 164507

164508

41845006

Activated Sludge, Respiration 

Inhibition Test

OECD 209 EC50 of >5.7 mg/l 

(water solubility of 

parent compound)

25 % respiration 

inhibition at 5.7 

mg/L

Not applicable 

Study does not 

measure 

degradates

Unacceptable 46816305

Study was previously considered 

to be acceptable but the water 

solubility from 40808501 is 14 

ppm, which is >5.7 ppm. 

Therefore, the study is now 

unacceptable and requires 

repeating.

Ready Biodegradability OECD 301B Not readily 

biodegradable

80 % degradation 

in 28-day study 

and 52% 

degradation by 10-

day period 

Not applicable 

Study does not 

measure 

degradates other 

than CO2

Satisfied

(all studies were 

acceptable)

46780743

DCOIT

20-23 o

C

Readily 

biodegradable

88.4 % 

degradation in 28-

day study and 65.1 

% degradation in 

10-day period.

46780741

N-(n-octyl) malonamic acid

20-23 o

C

Readily 

biodegradable

46780742

N-(n-octyl) acetamide

Page 48 of 77
89.1 % 

degradation in 28-

day study and 65.3 

% degradation in 

10-day period

20-23 oC

Soil Microorganisms: 

Nitrogen Transformation Test

OECD 216 EC50 of 155 mg/kg Not applicable

Degradates not 

tracked in study

Acceptable 46780727

19.5-21 oC

Soil Microorganisms: Carbon 

Transformation Test

OECD 217 EC50 of 393 mg/kg Not applicable

Degradates not 

tracked in study

Acceptable 46780727

19.5-21 oC

Activated Sludge Adsorption 

Isotherm Test

835.1110 Kd of 2,466 L/kg Degradates not 

analyzed.

Acceptable 46780735

Page 49 of 77
Table B2 Results of Wood Leaching Studies17,18,19

Study Description Test Guideline Leaching rate Status MRID and 

comments

Wood leaching study in 

water (block study) 

AWPA EN-84 2.2 (max)

0.9 (min)

1.7 (average)

19.8 (cumulative)

Acceptable 46780750

Wood leaching study in 

water (block study)

AWPA E11-97 1.6 (max)

0.05 (min)

0.36 (average)

3.5 (cumulative)

Acceptable 48168201

Wood leaching study in 

water (block study)

AWPA E11-06 Data to be reviewed No record of 

review

48414312

Ecolife One-Pack 

Wood leaching study in 

water (block study)

AWPA E11-06 Data to be reviewed No record of 

review

48424701

Ecolife One-Pack 

Leachability of Wood 

Preservatives in Soil 

Contact (stake study)

AWPA E20-08 Data to be reviewed No record of 

review

48236002

Table B3 Leaching from Treated Boat Paints (ASTM D5108-90)

Study Identification 

(MRID)

Study Result20 Study Status Comments

43468402

44239501

37.8 (max)

18.6 (min)

27.6 (average)

1,196 (cumulative)

Acceptable 45-day study

Red Paint 

3 % DCOIT

43768605 36.5 (max)

1.2 (min)

14.5 (average)

868 (cumulative)

Acceptable 73-day study

Sea-Nine 211

Hempel Formulation 7199E-19990

2.02 % DCOIT

43.4 (max)

6.6 (min)

23.7 (average)

1,510 (cumulative)

Acceptable 73-day study

Sea-Nine 211

Hempel Formulation 7199E-51110

Red Paint

1.97 % DCOIT

46439601 57.3 (max)

9.0 (min)

25.9 (average)

1,057 (cumulative)

Acceptable 45-day study

Sea-Nine 211

Hempel Antifouling Globic 81920

Red Paint

1.9 % DCOIT

44066802 34.8 (max)

7.6 (min)

Acceptable Sea-Nine 211

45-day study

17 Max, min, and average leaching rates in ug/cm2

/day. 18 Cumulative leaching in ug/cm2

. 19 Degradates not measured in study. 20 Maximum, minimum, and average leaching rates in ug/cm2

/day and cumulative leaching in ug/cm2.

Page 50 of 77

 
16 (average)

665 (cumulative)

Courtaulds Coatings Lot CPBB002 

Blue Paint

3.49 % DCOIT

49.8 (max)

17.3 (min)

28.5 (average)

1,157 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Coatings Lot CPBB004 

Blue Paint

3.75 % DCOIT 

10.9 (max)

6.8 (min)

8.6 (average)

376 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Coatings Lot CPBB006 

Blue Paint

2.7 % DCOIT 

44317710 5.2 (max)

0 (min)

1.8 (average)

92 (cumulative)

Acceptable Sea-Nine 211

45-day study

No-Foul SN-1

White Paint

2 % DCOIT 

44110102 46.8 (max)

13.5 (min)

23.4 (average)

949 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Lot No. CPBB038

Blue Paint

2.98 % DCOIT 

100.6 (max)

22.6 (min)

50.8 (average)

2,174 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Lot No. CPBB043

Blue Paint

1.96 % DCOIT 

93.6 (max)

27.1 (min)

48(average)

1,977 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Lot No. CPBB031

Blue Paint for Fiberglass

2.82 % DCOIT 

63.0 (max)

27.3 (min)

42.3 (average)

1,849 (cumulative)

Acceptable Sea-Nine 211

45-day study

Courtaulds Lot No. CPBB046-09

Clear Paint

3.69 % DCOIT 

44627102 48.7 (max)

13.3 (min)

20.9 (average)

869 (cumulative)

Acceptable Sea-Nine 211

45-day study

Jotun Valspar 60A5000 Sea Victor 50

Red Paint

2.44 % DCOIT

45673201 20.8 (max)

6.0 (min)

10.4 (average)

449 (cumulative)

Acceptable Sea-Nine 211

45-day study

Sigma Nexxium 20 Paint

Reddish-Brown Paint

3.43 % DCOIT

45578401 70.3 (max)

19.9 (min)

44.5 (average)

1,989 (cumulative)

Acceptable Sea-Nine 211

45-day study

No Foul SN-1 Black Antifouling Paint

3 % DCOIT

45578402 75.6 (max)

20.6 (min)

49.2 (average)

Acceptable Sea-Nine 211

45-day study

No Foul SN-1 Blue Antifouling Paint

Page 51 of 77
2,250 (cumulative) 3 % DCOIT

45578201 15.7 (max)

6.8 (min)

10.4 (average)

455 (cumulative)

Acceptable Sea-Nine 211

45-day study

Hempel’s Antifouling Globic SP-

ECOI 81952-50300 Antifouling Paint

Light Red

2 % DCOIT

45578204 21.6 (max)

8.7 (min)

13.7 (average)

566 (cumulative)

Acceptable Sea-Nine 211

45-day study

Hempel’s Antifouling Globic SP-

ECOI 81952-51110 Antifouling Paint

Red

2 % DCOIT 

45752201 19 (max)

3.5 (min)

9.0 (average)

347 (cumulative)

Acceptable Sea-Nine 211

45-day study

Sigmaplane Ecol HA 5294 Brown 

Antifouling Paint

2.4 % DCOIT 

45752202 19.2 (max)

2.9 (min)

8.1 (average)

286 (cumulative)

Acceptable Sea-Nine 211

45-day study

Sigmaplane Ecol HA 5294 Green 

Antifouling Paint

2.4 % DCOIT 

45752203 17.5 (max)

1.7 (min)

6.6 (average)

218 (cumulative)

Acceptable Sea-Nine 211

45-day study

Sigmaplane Ecol HA 5294 Blue 

Antifouling Paint

2.4 % DCOIT 

45752204 24.8 (max)

4.7 (min) 10.6 (average)

378 (cumulative)

Acceptable Sea-Nine 211

45-day study

Sigmaplane Ecol HA 5294 Black 

Antifouling Paint

2.4 % DCOIT 

44879701 14 (max)

1.7 (min)

5.3 (average)

207 (cumulative)

Acceptable Sea-Nine 211

45-day study

Reddish-brown paint

2.5 % DCOIT

46088608 12.7 (max)

3.6 (min)

6.0 (average)

278 (cumulative)

Acceptable Sea-Nine TM21 

45-day study

Sea Grand Prix CF-10 paint

3.66 % DCOIT

44753401 34.7 (max)

8.1 (min)

21.2 (average)

891 (cumulative)

Acceptable Sea-Nine 

45-day study

Marine Antifoulant and Yacht Paint

Formulation No. BOA 341

3.186 % DCOIT

36.5 (max)

15.2 (min)

21.2 (average)

915 (cumulative)

Acceptable Sea-Nine 

45-day study

Marine Antifoulant and Yacht Paint

Formulation No. BOA 344

3.108 % DCOIT

34.4 (max)

18.0 (min)

22.6 (average)

979 (cumulative)

Acceptable Sea-Nine 

45-day study

Marine Antifoulant and Yacht Paint

Formulation No. BOA 347

Page 52 of 77
3.175 % DCOIT

20.8 (max)

11.8 (min)

14.7 (average)

640 (cumulative)

Acceptable Sea-Nine 

45-day study

Marine Antifoulant and Yacht Paint

Formulation No. XUU 781

2.147 % DCOIT

9.0 (max)

5.3 (min)

6.9 (average)

298 (cumulative)

Acceptable Sea-Nine 

45-day study

Marine Antifoulant and Yacht Paint

Formulation No. XUU 843

3.104 % DCOIT

Works Cited

MRID 00164507. Forbis, A.; Georgie, L.; Bunch, B. (1985) Uptake, Depuration and 

Bioconcentration of [Carbon 14]-RH-5287 by Bluegill Sunfish (Lepomis macrochirus): ABC 

Final Report #32970. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, 

Inc. 256 p.

MRID 00164508. Leak, T. (1986) Metabolite Characterization of RH-5287 in Bluegill Sunfish 

(Lepomis macrochirus): ABC Final Report #32971. Unpublished study prepared by Analytical 

Bio-Chemistry Laboratories, Inc. 167 p.

MRID 00164668. Warren, J. (1986) Determination of Adsorption/Desorption Constants of C9211/[Carbon 14]-RH-5287: Report No. 32116: Amended Final Report. Unpublished Rohm and 

Haas's No. 310-86-31 prepared by Analytical Bio-Chemistry Laboratories, Inc. 375 p.

MRID 41845001. Kesterson, A.; Lawrence, B.; Lawrence, L. (1990) "Aqueous Photolysis of 

[Carbon 13/14] RH-5287 in Natural Sunlight": Photodegradation in Water: Lab Project Number: 

292: 1303: 34-90-73. Unpublished study prepared by PTRL East, Inc. 110 p.

MRID 41845002. Kesterson, A.; Lawrence, B.; Lawrence, L. (1991) Anaerobic Aquatic 

Metabolism of [Carbon 13/14] RH-5287: Anaerobic Aquatic Metabolism Studies: Lab Project 

Number: 1313: 295: 34-91-06. Unpublished study prepared by PTRL East, Inc. 87 p.

MRID 41845003. Lawrence, L.; Lawrence, B.; Jackson, S.; et al. (1991) Aerobic Aquatic 

Metabolism of [carbon 13/14] RH-5287: Final Report Re- Issue: Lab Project Number: 1291: 

294: 34-91-01. Unpublished Study prepared by PTRL East, Inc. 79 p.

MRID 41845004. Olson, G.; Lawrence, L. (1991) Soil Adsorption/Desorption of [Carb- on 

13/14] RH-5287 by the Batch Equilibrium Method: Mobility Studies Leaching and Adsorption/ 

Desorption Studies: Lab Project Number: 1246: 296: 34-90-28. Unpublished study prepared by 

PTRL East, Inc. 67 p.

MRID 41845005. Olson, G.; Lawrence, L. (1991) "Leaching of [Carbon 13/14] RH-5287 in 

Four Soil Types Following 30 Days or One Half-life of Aerobic Aging in Sandy Loam Soil: Lab 

Project Number: 1296: 297: 34-90-6 7. Unpublished study prepared by PTRL East, Inc. 71 p. 

Page 53 of 77
MRID 41845006. Santangelo, M.; Jacobson, A.; Derbyshire, R.; et al. (1991) Metabolism of 

RH-5287 in Bluegill Sunfish: Lab Project Number: 34-90-7 1. Unpublished study prepared by 

Rohm and Haas Co. 86 p.

MRID 42341101. Kesterson, A.; Atkins, R. (1992) Supplemental Study on the Anaerobic 

Aquatic Metabolism of carbon 13/14| RH-5287: Lab Project Number: 295: 1313: 34-92-46. 

Unpublished study prepared by PTRL-East, Inc. 27 p.

MRID 42341102. Kesterson, A.; Atkins, R. (1992) Supplemental Study on the Aerobic Aquatic 

Metabolism of carbon 13/14| RH-5287: Lab Project Number: 294: 1291: 34-92-13. Unpublished 

study prepared by PTRL-East, Inc. 29 p.

MRID 42772801. Mazza, L. (1993) Supplemental Study on the Aqueous Photolysis of (carbon 

14) RH-5287 in Natural Sunlight: Lab Project Number: 34-92-98. Unpublished study prepared 

by Rohm and Haas Co. 116 p.

MRID 42772802. Mazza, L. (1993) Supplemental Study on the Aerobic Aquatic Metabolism of 

RH-5287: Lab Project Number: 34-93-31. Unpublished study prepared by Rohm and Haas Co. 

85 p.

MRID 43468402. Anthony, C. (1991) Leach Rate Determinations of Antifoulant Paint 

Containing RH-287: Data Acquired Using Draft Interim ASTM Test Method For Organotin 

Release Rates of Antifoulant Coating Systems in Sea Water: Lab Project Number: B-92-43. 

Unpublished study prepared by Case Consulting Labs, Inc. 56 p.

MRID 43768605. Marbo, M. (1995) Dynamic Leach Rate of RH-287 from Marine Antifoulant 

(MAF) Paint (Hempel's Antifouling Combic Tin Free 7199E): Lab Project Number: BER000: 

TR-94-51: 29P-94-016. Unpublished study prepared by Rohm and Haas Co. 154 p.

MRID 44066802. Marbo, M. (1995) Dynamic Leach Rate of RH-287 from Marine Antifoulant 

(MAF) Paint: Lab Project Number: 24P-95-010: BNAR0R: TR-95-27. Unpublished study 

prepared by Rohm and Haas Co. 179 p.

MRID 44110102. Hitchen, D. (1996) Dynamic Leach Rate of RH-287 from Marine Antifoulant 

(MAF) Paint: Lab Project Number: BNAR0M: TR-96-02: 24P-95-014. Unpublished study 

prepared by Rohm and Haas Co. 130 p.

MRID 44239501. Anthony, C. (1997) Leach Rate Determinations of Antifoulant Paint 

Containing RH-287: Lab Project Number: 03779: B-92-43. Unpublished study prepared by Case 

Consulting Labs., Inc. 56 p.

MRID 44317710. Willis, C. (1997) Leach Rate Determination of No Foul SN-1 Antifoulant 

Paint Containing RH-287: Final Report: Lab Project Number: 1460-01: D 5108-90. Unpublished 

study prepared by Case Consulting Labs., Inc. 34 p.

MRID 44627102. Willis, C. (1997) Leach Rate Determination of Jotun Valspar 60A5000 Sea 

Victor 50 Antifouling Paint Containing RH-287: Lab Project Number: 920-04. Unpublished 

study prepared by Case Consulting Laboratories, Inc. 33 p.

Page 54 of 77
MRID 44753401. Patel, A. (1998) Release Rate Determination of Sea-Nine 211 Active 

Ingredient (RH-287) from Marine Antifoulant and Yacht Paints: Lab Project Number: BNAR0R: 

TR-98-082. Unpublished study prepared by Courtaulds Coatings Inc. 218 p.

MRID 44879701. Willis, C. (1997) Leach Rate Determination of an Antifouling Paint 

Containing RH-287: Lab Project Number: 920-03: 5108-90. Unpublished study prepared by 

Case Consulting Labs., Inc. 40 p.

MRID 44791101. Reynolds, J. (1999) Aerobic Soil Metabolism of (carbon 14) RH-5287: Lab 

Project Number: XBL95001: RPT00433: 34P-94-70. Unpublished study prepared by 

XenoBiotics Laboratories, Inc. 289 p.

MRID 45578201. Sinning, D. 2001. Leach Rate Determination of Hempel’s Antifouling 

Globic SP-ECO 81952-50300 Paint Containing Sea Nine 211TM Antifouling Agent. 

Unpublished study prepared by Case Consulting Laboratories, Inc. 11p.

MRID 45578204. Sinning, D. 2001. Leach Rate Determination of Hempel’s Antifouling 

Globic SP-ECO 81952-51110 Paint Containing Sea Nine 211TM Antifouling Agent. 

Unpublished study prepared by Case Consulting Laboratories, Inc. 23p.

MRID 45578401. Sinning, D. (2001) Leach Rate Determination of No Foul SN-1 Black 

Antifouling Paint Containing Sea Nine 211 (RH-287) Antifouling Agent: Lab Project Number: 

2140-05. Unpublished study prepared by Case Consulting Laboratories, Inc. 20 p.

MRID 45578402. Sinning, D. (2001) Leach Rate Determination of No Foul SN-1 Blue 

Antifouling Paint Containing Sea Nine 211 (RH-287) Antifouling Agent: Lab Project Number: 

2140-04. Unpublished study prepared by Case Consulting Laboratories, Inc. 20 p.

MRID 45673201. Sinning, D. (2002) Leach Rate Determination of Sigma Nexxium 20 Paint 

Containing Sea Nine 211 and AFO28 Antifoulings: Lab Project Number: 630-16. Unpublished 

study prepared by Case Consulting Laboratories, Inc. 34 p.

MRID 45752201. Sinning, D. 2002. Leach Rate Determination of Sigmaplane Ecol HA 5294 

Brown Antifouling Paint Containing Sea NineTM (RH-287) Antifouling Agent. Unpublished 

study prepared by Case Consulting Laboratories, Inc. 22p.

MRID 45752202. Sinning, D. 2002. Leach Rate Determination of Sigmaplane Ecol HA 5294 

Green Antifouling Paint Containing Sea NineTM (RH-287) Antifouling Agent. Unpublished 

study prepared by Case Consulting Laboratories, Inc. 22p.

MRID 45752203. Sinning, D. 2002. Leach Rate Determination of Sigmaplane Ecol HA 5294 

Blue Antifouling Paint Containing Sea NineTM (RH-287) Antifouling Agent. Unpublished study 

prepared by Case Consulting Laboratories, Inc. 22p.

Page 55 of 77
MRID 46088608. Sinning, D. (2003) Leach Rate Determination of Sea Nine TM21 1 

Antifouling Agent and Zinc Omadine from Sea Grand Prix CF-10: Final Report. Project 

Number: 2750/03. Unpublished study prepared by Case Consulting Laboratories, Inc. 34 p.

MRID 46439601. Sinning, D. (2004) Leach Rate Study for Sea-Nine 211. Project Number: 

320/52. Unpublished study prepared by Case Consulting Laboratories, Inc. 22 p.

MRID 46780727. van der Kolk, J. (2002) RH-287 Technical: Determination of the Effects on 

Soil Microflora Activity: Final Report. Project Number: 01RC/142, 1007/079/747. Unpublished 

study prepared by Springborn Laboratories (Europe) Ag. 74 p.

MRID 46780735. Swales, S. (2002) (Carbon 14)-RH-287 Technical: Activated Sludge 

Adsorption Isotherm: Final Report. Project Number: 616/30, 616/30/D2149, 02RC/0029. 

Unpublished study prepared by Covance Laboratories, Ltd. 88 p.

MRID 46780741. Seyfried, B. (2003) Ready Biodegradability of N-(N-Octyl) Malonamic Acid 

in a CO2 Evolution (Modified Sturm) Test. Project Number: 843969, 24P/2002/026, 

GLP/2003/033. Unpublished study prepared by RCC Umweltchemie Ag. 44 p. 

MRID 46780742. Seyfried, B. (2003) Ready Biodegradability of N-(N-Octyl) Acetamide in a 

CO2 Evolution (Modified Sturm) Test. Project Number: 843970, 24P/2002/027, GLP/2003/034. 

Unpublished study prepared by RCC Umweltchemie Ag. 44 p.

MRID 46780743. Seyfried, B. (2003) Ready Biodegradability of RH-25,287 in a CO2 Evolution 

(Modified Sturm) Test. Project Number: 847085, 24P/2003/009. Unpublished study prepared by 

RCC Umweltchemie Ag. 38 p.

MRID 46780744. Marbo, M. (2001) Hydrolysis of (Carbon 14)-RH-5287 at pH 4,7, and 9, at 25 

and 40(Degrees) C. Project Number: TR/01/012, 24P/99/011, TD2001/090. Unpublished study 

prepared by Rohm and Haas Co. 108 p. 

MRID 46780750. Broughton, H. (2005) Leachates from RH-287 Treated Wood. Project 

Number: 24P/2005/043, GLP/2005/070, 226/519. Unpublished study prepared by BRE. 228 p.

MRID 46816305. Ward, T.; Kowalski, P.; Boeri, R. (1997) Activated Sludge Respiration 

Inhibition Test with RH-287. Project Number: 96RC/0129, 1034/RH. Unpublished study 

prepared by T.R. Wilbury Laboratories, Inc. 47 p.

MRID 46816306. Millais, A. (2005) (Carbon 14)-RH-5287: Degradability and Fate in the Water 

Sediment System. Project Number: 24P/2002/002, TR/05/93, RAS/262. Unpublished study 

prepared by Rohm and Haas Co. and Huntingdon Life Sciences, Ltd. 214 p.

MRID 46816307. Guo, I.; Jacobson, A.; Eisenschmied, M. (2004) Aerobic Transformation of 

RH-5287 in Surface Water. Project Number: 24P/2001/033, GLP/2004/26, 3969/08. 

Unpublished study prepared by Rohm and Haas Co. 192 p.

Page 56 of 77
MRID 48168201. Ashmore, J. (2010) Determination of RH-287 Leached from Southern Pine 

Treated with Kathon 287WT According to AWPA E11-97 Test Protocol. Project Number: 

GLP/2010/020, AWPA/E11/97. Unpublished study prepared by Rohm and Haas Co. 20 p.

MRID 48236002. Jin, L. (2009) Kathon 287-WT - Soil Depletion Study in Accordance with 

American Wood Protection Association Standard E20. Project Number: ELP001. Unpublished 

study prepared by Viance, LLC. 20 p.

MRID 48414312. Doshi, D. (2011) Determination of DCOIT in Water Leached from Southern 

Pine Treated with Ecolife One-Pack. Project Number: GLP/2011/011, 24P/2011/004. 

Unpublished study prepared by Dow Chemical Company. 12 p.

MRID 48424701. Laganella, D. (2011) Determination of Ecolife One-Pack Leaching Using 

AWPA E11 for Active Ingredient 4,5-Dichloro-2-n-Octyl-4-Isothiazolin-3-One (DCOIT, RH287). Project Number: 24P/2011/004, 24P/2011/005, GLP/2011/018. Unpublished study 

prepared by Dow Chemical Company. 19 p.

Page 57 of 77
Appendix C Ecotoxicology 

Profile

Toxicity to Terrestrial Receptors 

Birds, Acute and Subacute

For wood product uses, an acute oral toxicity study using the technical grade of the active 

ingredient (TGAI) is required to establish the toxicity of these chemicals to birds. The preferred 

test species is either mallard duck (a waterfowl) or northern bobwhite quail (an upland game 

bird). Several avian acute toxicity studies were found in the agency’s files for this chemical. 

Avian acute oral toxicity testing (850.2100/71-1), preferably using the bobwhite quail, is 

required to support the registration of this chemical. 

Avian dietary toxicity studies using the TGAI of these chemicals are not required for these uses. 

The results from the avian acute toxicity and dietary studies obtained from the agency’s files are 

summarized in the table below (Table C1).

Table C1 

Test and 

Organism 

Results LC50

(mg/L) or LD50

(mg/kg)

Toxicity Category Comments Reference

Avian dietary 

LC50 Bobwhite 

Quail (Colinus 

virginianus)

>4,639 

NOEC = 11,112 

Practically nontoxicCore study Pedersen & 

Helsten. 1992 

MRID# -

42214901 

Avian dietary 

LC50 Mallard 

Duck (Anas 

platyrhynchos)

>4.369 

NOEC = 529

Practically nontoxicCore study Pedersen & 

Helsten. 1992

MRID# -

42214902 

Eight –day avian 

dietary LC50

Mallard Duck 

(Anas 

platyrhynchos)

>10,000 Practically nontoxicCore Study Fink, R. 1976

ACC.# - 249935

Acute oral LD50

Mallard Duck 

(Anas

platyrhynchos)

>2,784 Practically nontoxicCore Study Fink, R. 1976

ACC# - 249935

Page 58 of 77
The results of the dietary avian studies indicate that Kathon is practically non-toxic to both 

mallard duck and bobwhite quail. In the acute oral study, the chemical was found to be 

practically non-toxic to mallard duck. All of these studies were considered to be core and met 

guideline requirements at the time they were submitted to the agency. 

Mammals

A wild mammal test is not required by the agency. Mammalian toxicity values obtained from 

studies conducted to support data requirements for human health risk assessments substitute for 

wild mammal testing. In subchronic toxicity testing RH-287 was administered to beagles in the 

diet for 13 weeks. No treatment–related effects were observed on survival, clinical or 

neurobehavioral findings, ophthalmology, physical examinations, organ weights or macroscopic 

pathology in either sex at < 1500 ppm (Serota, D.G. 2002: MRID# 45747201) 

A summary of mammalian toxicity of Kathon is presented in the “Evaluation of Toxicity 

Database for Registration Eligibility Decision Document Disciplinary Chapter”. 

Toxicity to Aquatic Receptors

Freshwater Fish, Acute

Freshwater fish toxicity studies using the TGAI are required to establish the toxicity of chemicals 

to fish. Data are generally required for only one species. Testing in two fish species is required 

for stable chemicals with high volume effluents (e.g., including, but not limited to, egg washing, 

fruit and vegetable rinses, swimming pools or materials preservatives) and if the LC50 in the first 

species is greater than (>) 1 ppm. The preferred test species are rainbow trout (a coldwater fish) 

and bluegill sunfish (a warmwater fish), although other test species identified in the OPPTS 

Guideline (i.e., OPPTS 850.1075 (e)(4)(i)(A)) may also be used. Several freshwater fish acute 

toxicity studies were identified from peer-reviewed literature (Table C2). Several freshwater fish 

acute toxicity studies were found in the Agency’s files (Table C3). Freshwater fish acute 

toxicity testing (850.1075/72-1) on both species, the rainbow trout and bluegill sunfish, are 

required to support the registration of this chemical. 

The results from freshwater fish acute toxicity studies obtained from the Agency’s files are 

summarized in the table below (Table C2). 

Page 59 of 77
Table C2 

Test and 

Organism 

Results LC50

(ug a.i./L)

Toxicity 

Category

Comments Reference

Acute 96-hr 

toxicity to 

Rainbow 

Trout 

determined 

under static 

conditions 

(Oncorhynchus 

mykiss)

25 mg ai/L Slightly toxic Supplemental 

Study

(Test chemical 

is Acetamide)

Rhodes, J.E., 

2002

MRID# -

467807-32 

Acute 96-hour 

Freshwater 

Fish Toxicity 

Bluegill 

Sunfish 

(Lepomis 

macrochirus)

1.4 Very Highly 

toxic

Core Study 1991

MRID# -

41465801

Acute 96-hour 

Freshwater 

Fish Toxicity 

Rainbow 

Trout 

(Oncorhynchus 

mykiss)

2.7 Very Highly 

toxic

Core Study 1991

MIRD# -

41465802

Acute Toxicity 

LC50 Bluegill 

Sunfish 

(Lepomis 

macrochirus)

22 Very Highly 

toxic

Supplemental 

Study

Buccafusco, 

R.J. 1977

ACC.# -

249935

Acute Toxicity 

LC50 Bluegill 

Sunfish 

(Lepomis 

macrochirus)

29 Very Highly 

toxic 

Supplemental 

Study

Buccafusco, 

R.J. 1976

ACC.# -

249935

Acute Toxicity 

LC50

Sheepshead 

minnow 

22 Very Highly 

toxic

Core Study Heitmuller, T. 

1983

Page 60 of 77
(Cyprindon 

variegates)

ACC.# -

249935

Acute Toxicity 

LC50 Rainbow 

Trout (Salmo 

gairdneri) 

10 Very Highly 

toxic

Supplemental 

Study

Buccafusco, 

R.J. 1977

ACC.# -

249935

Acute Toxicity 

96-hr LC50

Rainbow 

Trout 

(Oncorhynchus 

mykiss)

9.7 Very Highly 

toxic

Supplemental 

Study

Buccafusco, 

R.J. 1976

ACC.# -

249935

As shown in Table C2, the toxicity ranged from 1.4 to 29 ppb, which indicated that this chemical 

was very highly toxic to fish. 

Freshwater or Estuarine/Marine Fish, Chronic

Fish early life stage toxicity test using the TGAI is required to establish the chronic toxicity of a 

pesticide to fish. The preferred test species is the most sensitive species – freshwater or 

estuarine/marine. A fish early-life stage study testing the TGAI and using the most sensitive 

species, either freshwater or estuarine/marine is required for the registration of this 

chemical (850.1300/850.1400/72-4). Two studies were found in the agency’s files (See Table 

C3). 

Table C3

Test and 

Organism

Results Toxicity 

Category

Comments Reference

Marine Fish 

Early Life Stage 

Toxicity Test 

Sheepshead 

Minnow 

(Cyprinodon 

variegates)

NOEC = 2.9 ug 

a.i./L

LOEC = 6.0 ug 

a.i./L for 

percent hatch

Supplemental 

Study

Ward, T.J. & 

Boeri, R.L. 

1990 MRID# -

41741504

Freshwater Fish 

Early Life Stage 

Toxicity Test 

Rainbow Trout 

61 days posthatch (growth)

NOEC = 0.56 

ug a.i./L

Core Study Rhodes, J.E. 

2003

MRID# -

45865201

Page 61 of 77
(Oncorhynchus 

mykiss)

LOEC = 1.2 ug 

a.i./L

MATC = 0.82 

ug a.i./L 

As shown in table 3, the NOEC for marine fish was 2.9 ug a.i./L and for freshwater fish the 

NOEC was 0.56 ug a.i./L. The Agency re-examined the sheepshead minnow study and 

determined that the study would remain classified as supplemental, but would not need to be 

repeated by the registrant. The NOEC was revised to a lower number (2.9 instead of 6.0 ug 

a.i./L) and can be used in a risk assessment of this chemical. The rainbow trout study was core 

and the results can be used in a risk assessment.

Freshwater Invertebrates, Acute 

A freshwater aquatic invertebrate toxicity test using the TGAI is required to establish the toxicity 

of a pesticide to aquatic invertebrates. The preferred test species is Daphnia magna or Daphnia 

pulex. Several studies testing these organisms were found in the agency’s files (Table C4). 

Freshwater invertebrate acute toxicity testing (850.1010/72-2) is required for the registration of 

this chemical. 

Table C4

Test and 

Organism

Results Toxicity 

Category

Comments Reference

Acute toxicity 

to the water 

flea 

determined 

under static 

conditions, 

Daphnia 

magna

48-hr EC50 = 

28 mg ai/L

48-hr NOEC = 

9.5 mg ai/L

Slightly toxic Core Study 

(Test chemical 

is Acetamide)

Rhodes, J.E. 

2002 

MRID# -

467807-33 

Acute toxicity 

to the water 

flea under 

static 

conditions, 

Daphnia 

magna 

24-hr EC50 = 

>282 mg ai/L

48-hr EC50 = 

157 mg ai/L

48-hr NOEC = 

69 mg ai/L

Practically 

nontoxic

Supplemental 

Study

(Test chemical 

is Malonamic 

Acid)

Hahne, R. 2002

MRID# -

467807-31

Page 62 of 77
Freshwater 

invertebrate 

flow-thru 

toxicity 

Daphnia 

magna

48-hr. EC 50 = 

5.2 ug a.i./l

Very highly 

toxic

Core Study 1992

MRID# -

41741501 

Freshwater 

Invertebrate 

Static Acute 

Toxicity 

Daphnia 

magna

48-hr. LC50 = 8 

ug a.i./l

Very highly 

toxic

Core Study Buccafusco, 

R.J. 1977

ACC.# -

249935

Freshwater 

Invertebrate 

Static Acute 

Toxicity 

Daphnia 

magna

48-hr. LC50 = 

9.2 ug a.i./L 

Very highly 

toxic

Core Study Buccafusco, 

R.L. 1976

ACC.# -

249935

As shown in Table C4, this chemical is very highly toxic to aquatic invertebrates.

Freshwater and Marine Invertebrates, Chronic 

Chronic aquatic invertebrate testing (OPPTS 850.1350) is conditionally required for the currently 

registered wood preservative use of this chemical. Two studies were found in the agency’s files 

(Table C5).

Table C5

Test and 

Organism

Results Toxicity 

Category

Comments Reference

Chronic 

Toxicity in 

Whole Sediment 

to the 

Freshwater 

Midge 

(Chironomus 

riparius)

10-day survival 

LC50 or EC50 

= 13 mg/kg dry 

sediment, 

NOEC = 4.9 

mg/kg dry 

sediment

10-day dry 

weight LC50 or 

EC50 = >14 

mg/kg dry 

sediment, 

NOEC = 14 

Slightly toxic Core Study Aufderheide, J 

2003

MRID# -

468163-04

Page 63 of 77
mg/kg dry 

sediment

% adult 

emergence 

LC50 or EC50 

= 22 mg/kg dry 

sediment, 

NOEC = 9.7 

mg/kg dry 

sediment

Whole Sediment 

Chronic 

Toxicity Test 

Marine 

Invertebrate 

(Ampelisca 

abdita)

LC50 = 320 (mg 

ai/kg dry 

sediment)

NOEL 6.9 

mg/kg

Practically nontoxicSupplemental 

Study

Putt, A.E. 1994

MRID# -

44755903

Flow-Thru 

Chronic 

Toxicity 

Mysid 

(Americamysis 

bahia)

28-day LC50 = 

>2.5 ug/L

LOEC = 1.24 

ug/L

NOEC = 0.627 

ug/L

MATC = 0.882 

ug/L

None given Core study Ward, T.J. & 

Boeri, R.L. 

2000 

MRID# -

45153101 

Chronic 

Toxicity in 

Whole Sediment 

to the Marine 

Amphipod 

(Leptocheirus 

plumulosus)

28-day LC50 = 

>78 ug/kg dry 

sediment 

LOEC = 19 

mg/kg 

NOEC = 10 

mg/kg 

MATC = 14 

mg/kg

Slightly toxic Supplemental 

study

Jones, A. and 

Aufderheide, J. 

2003 

MRID# -

467807-36

Page 64 of 77
Chronic 

Toxicity in 

Whole Sediment 

to the Marine 

Polychaete 

(Neanthes 

arenaceodentata) 

28 day LC50 = 

>69 mg/kg dry 

sediment

LOEL = >69 

mg/kg

NOEC = 69 

mg/kg

Slightly toxic Invalid study Hughes, C. and 

Aufderheide, J. 

2003

MRID# -

467807-38

The results of the above study indicate that Kathon is practically non-toxic to a marine 

invertebrate in a whole sediment chronic toxicity test. The test was considered supplemental. 

This chemical was chronically toxic in ppb to the mysid. 

Estuarine and Marine Organisms

Acute toxicity testing with estuarine and marine organisms using the TGAI 

(850.1026/850.1035/850.1045/850.1075/72.3) is conditionally required for the registration of 

this chemical. Acute LC50 testing with an estuarine/marine fish, mollusk and shrimp 

species is required for the registration of this chemical. Several studies on marine/estuarine 

invertebrates were found in the agency’s files (Table C6).

Table C6

Test and 

Organism

Results Toxicity 

Category

Comments Reference

Acute toxicity in 

whole sediment 

to the marine 

amphipod 

(Leptocherirus 

plumulosus)

10-day LC50 = 

95.4 mg/kg dry 

sediment

NOEC 

(survival) = 

64.8 mg/kg dry 

sediment

LOEC 

(survival) = 

133 mg/kg dry 

sediment

Slightly toxic Supplemental 

Study

Aufderheide, 

J.A. 2002

MRID# -

467807-40

Acute Static 

Estuarine/Marine 

Invertebrate 

Toxicity, Mysid 

Shrimp 

96-hr. LC50 = 

4.7 ug a.i./L 

Very highly 

toxic 

Core Study 1992

MRID# - 

41741503

Page 65 of 77
(Mysidopsis 

bahia)

Acute Static 

Estuarine/Marine 

Mollusk Toxicity,

Eastern Oyster 

(Crassostrea 

virginica) 

48-hour EC50 = 

24 ug a.i./L 

(in natural 

seawater) 

Very highly 

toxic

Supplemental 

study

1992

MRID# -

41756801

Acute Flow-thru 

Estuarine/Marine 

Fish Toxicity, 

Sheepshead 

Minnow 

(Cyprinodon 

variegates) 

96-hr. LC50 = 

20.5 ug a.i./L

Very highly 

toxic

Core Study 1992

MRID# -

41741502

Acute Toxicity 

Embryos-larvae 

of Bay Mussels 

(Mytilus edulis)

48-hr. EC50 = 

1.9 ug a.i./L

Very highly 

toxic

Supplemental 

Study 

Hollister, T. 

1979

ACC.# -

249935

Acute Toxicity to 

Bay Mussels 

(Mytilus edulis) 

96-hr. LC50 = 

850 ug a.i./L

Very highly 

toxic

Supplemental 

Study

Heitmuller, T. 

1979 ACC.# -

249935

Acute Toxicity 

Fiddler Crabs 

(Uca pugilator) 

96-hour EC50

= 1.7 mg a.i./L

Moderately 

toxic

Supplemental 

Study

Heitmuller, T. 

1977 ACC.# -

249935

Acute Toxicity 

Brown Shrimp 

(Penaeus aztecus)

96-hour LC50

= 16 ug a.i./L

Very highly 

toxic

Core Study Heitmuller, T. 

1977 ACC.# -

249935

Acute Toxicity 

Embryos of 

Eastern Oysters 

(Crassostrea 

virginica)

48-hour EC50

= 9 ug a.i./L

Very highly 

toxic

Core Study Hollister, T. 

1977 ACC.# -

249935

Bivalve Acute 

Toxicity Test 

(Embryo-Larval) 

with the Bay 

48-hr EC50 = 

0.411 mg ai/L

Very highly 

toxic

Invalid study Boeri, R.L., 

Wyskiel, D.C. 

and Ward, T.J. 

Page 66 of 77
Mussel (Mytilus 

edulis)

2001 MRID 

467807-29 

As shown in Table C6, this chemical is very highly toxic to mysid shrimp, eastern oyster, 

sheepshead minnow, bay mussel, fiddler crab and brown shrimp.

Toxicity to Plants

Terrestrial and aquatic plant testing is required for the registration of this chemical. Several 

terrestrial and aquatic plant toxicity studies on this chemical were found in the agency’s files 

(Table C7).

Table C7

Test and 

Organism

Results Toxicity 

Category

Comments Reference

Toxicity to the 

Saltwater 

Diatom 

(Skeletonema 

costatum)

96-hr EC50 = 

0.19 mg ai/L

NOEC = 0.13 

mg ai/L

Not used for 

plant studies

Supplemental 

Study

(Test chemical 

is Malonamic 

Acid)

Hahne, R. 2002

MRID# -

468163-10

96-hr. Toxicity 

Test with the 

Unicellular 

Green alga 

(Selenastrum 

capricornutum)

96-hr EC50 = 

9.7 mg ai/L

NOEC = 5.9 

mg ai/L

Not used for 

plant studies

Core Study Rhodes, J.E. 

2002

MRID# -

467807-34

96-hr. Toxicity 

Test BlueGreen Alga 

(Anabaena 

flos-aquae)

EC50 = 0.0058 

mg a.i./kg

NOEC = 

0.0028 ug 

a.i./kg

Not used for 

plant studies

Core Study Hughes, C. 

2002

MRID# -

45865202

Toxicity to the 

unicellular 

green alga 

(Selenastrum 

capricornum) 

96-hr EC50 = 

6.64 mg ai/L 

96-hr NOEC = 

1.82 mg ai/L

Not used for 

plant studies

Core Study 

(Test chemical 

is Malonamic 

Acid)

Hahne, R. 2001 

MRID# -

467807-30

Page 67 of 77
96-hr Toxicity 

Test with 

Unicellular 

Green Alga 

(Selenastrum 

capricornutum)

96-hour EC50 = 

0.047 mg 

a.i./kg 

NOEC = 

0.0078 mg 

a.i./kg

Not used for 

plant studies

Core Study Hughes, C. 

2002

MRID# -

45862503

Effects of 

Seedling 

Emergence 

and Growth, 

canola 

(Brassica 

napus), red 

clover 

(Trifolium 

pretense), rice 

(Oryza sativa)

Red clover 

EC25 = 8.4 mg 

a.i./l = kg

NOEC = 5.0 

mg a.i./kg

Canola

EC25 = 13.0 

mg a.i./kg

NOEC = 5.0 

mg a.i./kg

Rice

EC25 = 11.0 

mg a.i./kg

NOEC = 10 mg 

a.i./kg

Not used for 

plant studies

Core Study Teixeira, D. 

2002

MRID# -

45870601

Effects of 

Vegetative 

Vigor, canola 

(Brassica 

nupus), red 

clover 

(Trifolium 

prantense), rice 

(Oryza sativa)

Red clover

EC25 = 0.94 

mg a.i./kg

NOEC = 0.12 

mg a.i./kg

Rice 

EC25 = 4.7 mg 

a.i./kg

NOEC = 0.64 

mg a.i./kg

None given Core study Teixeira, D. 

2002

MRID# -

45905001

Page 68 of 77
Canola

EC25 = 3.7 mg 

a.i./kg

NOEC = 2.6 

mg a.i./kg

Toxicity to 

Duckweed 

(Lemna gibba) 

static 

conditions

Frond # EC50 = 

0.166 mg 

a.i./kg

NOEC = 

0.0118 mg 

a.i./kg

Not used for 

plant studies

Core study Rhodes, J.E. 

2002

MRID# -

45865204

Toxicity to 

marine alga 

(Skeletonema 

costatum)

96-hour EC50

(decrease in 

chlorophyll) = 

26 ppb

96-hour EC50

(decrease in 

cell numbers) = 

18 ppb 

Not used for 

plant studies

Supplemental 

study

Hollister, T.A. 

1977 

ACC.# -

249935 

As shown in Table C7, Kathon was toxic to freshwater alga at microgram concentrations.

 

REFERENCES

ACC # 249935: Buccafusco, R.J. (1976) Acute toxicity of RH-287 to bluegill, rainbow trout, 

and the water flea. Fish 96-hour LC50 (Bluegill). EG&G, Bionomics.

ACC # 249935: Buccafusco, R.J. (1976) Acute toxicity of RH-287 to bluegill, rainbow trout, 

and the water flea. Aquatic invertebrate 48-hour LC50. EG&G, Bionomics.

ACC # 249935: Buccafusco, R.J. (1976) Acute toxicity of RH-287 to bluegill, rainbow trout and 

the water flea. Fish 96-hour LC50 (Rainbow Trout). EG&G, Bionomics.

ACC# 249935: Buccafusco, R.J. (1977) Acute toxicity of C-9211 Technical to bluegill, rainbow 

trout and the water flea. Aquatic invertebrate 48-hour LC50. EG&G, Bionomics.

ACC# 229935: Buccafusco, R.J. (1977) Acute toxicity of C-9211 to bluegill, rainbow trout, and 

the water flea. Fish 96-hour LC50 (Rainbow Trout). EG&G, Bionomics.

Page 69 of 77
ACC # 249935: Buccafusco, R.J. (1977) Acute toxicity of C-9211 Technical to bluegill, 

rainbow trout and the water flea. Fish 96-hour LC50 (bluegill). EG&G, Bionomics.

ACC# 249935: Fink, R. (1976) Acute oral LD50 – Mallard Duck. Project No. 129-112. 

Wildlife International, Ltd.

ACC# 249935: Fink, R. (1976) Eight-day dietary LC50 – Mallard Duck. Project No. 192-110. 

Wildlife International, Ltd. 

ACC# 249935: Heitmuller, T. (1977) Acute toxicity of C-9211 to brown shrimp (Penaeus 

aztecus). EG&G, Bionomics. 

ACC# 249935: Heimuller, T. (1977) Acute toxicity of C-9211 to fiddler crabs (Uca pugilator). 

EG&G, Bionomics.

ACC# 249935: Heimuller, T. (1977) Acute toxicity of C-9211 to sheepshead minnows 

(Cyprinodon variegates). EG&G, Bionomics.

ACC#s 249935: Heimuller, T. (1979) Acute Toxicity of Biocide C-9211 to bay mussels (Mytilus 

edulis). EG&G, Bionomics. 

ACC# 249935: Hollister, T (1977) Acute toxicity of C-9211 to embryos of eastern oysters 

(Crassostrea virginica). EG&G, Bionomics.

ACC# 249935: Hollister, T. (1979) Acute toxicity of biocide C-9211 to embryos-larvae of bay 

mussels (Mytilus edulis). EG&G, Bionomics.

ACC# 249935: Hollister, T.A. (1977) Toxicity of C-9211 to the marine alga Skeletonema 

costatum. EG&G, Bionomics.

MRID# 414658-01: (1991) Acute 96-hour freshwater fish toxicity, bluegill sunfish (Lepomis 

macrochirus). 

MRID# 414658-02: (1991) Acute 96-hour freshwater fish toxicity, rainbow trout 

(Oncorhynchus myiss).

MRID# 417415-01: (1992) Freshwater invertebrate flow-thru toxicity to Daphnia magna.

EnviroSystems Division, Resource Analysts, Inc.

MRID# 417415-02: (1992) Acute flow-thru estuarine/marine fish toxicity, sheepshead minnow 

(Cyprinodon variegates). EnviroSystems Division, Resource Analysts, Inc.

MRID# 417415-03: (1992) Acute Static estuarine/marine invertebrate toxicity, mysid shrimp 

(Mysidopsis bahia). EnviroSystems Division, Resource Analysts, Inc.

MRID# 417415-04: Ward, T.J. and Boeri, R.L. (1990). Early life stage 

toxicity of RH-287 to the sheepshead minnow, Cyprinodon variegates. EviroSystems

Division, Resource Analysts, Inc. 

Page 70 of 77
MRID# 417568-01: (1992). Acute Static estuarine/marine mollusk toxicity, eastern

oyster (Crassostrea virginica).

MRID# 422149-1: Pedersen, C.A. and Helsten, B.R. (1992). RH-287 Technical: 8-day acute 

dietary LC50 study in bobwhite quail. Laboratory study ID. BLAL No. 111-001-01. Bio-Life 

Associates, Ltd. 

MRID# 422149-02: Pedersen, C.A. and Helsten, B.R. (1992). RH-287 Technical: 8-day acute 

dietary LC50 study in mallard ducklings. Laboratory study ID. BLAL No. 111-002-02. Bio-Life 

Associates, Ltd. 

MRID# 447559-03: Putt, A.E. (1994). RH-287 Technical – acute toxicity to amphipods 

(Ampelisca abdita) during a 10-day sediment exposure under static conditions. Springborn 

laboratories, Inc. 

MRID# 451531-01: Ward, T.J., and Boeri, R.L. (2000). RH-287: Flow-through chronic toxicity 

to the mysid, Americamysis bahia. T.R. Wilbury Laboratories, Inc. 

MRID# 458652-01: Rhodes, J.E. (2003). Early life-stage Toxicity of RH-287 Technical to the 

rainbow trout (Oncorhynchus mykiss). Study No. 46578. ABC Laboratories, Inc. 

MRID# 458652-02: Hughes, C. (2002). Toxicity of RH-287 Technical to the blue-green alga 

Anabaena flos-aquae. ABC Laboratories, Inc.

MRID# 458652-03: Hughes, C. (2002). Toxicity of RH-287 Technical to the unicellular green 

alga, Selenastrum capricornutum. ABC Laboratories, Inc.

MRID# 458652-04: Rhodes, J.E. (2002). Toxicity of RH-287 Technical to Duckweed (Lemna 

gibba) G3, determined under static test conditions. ABC Laboratories, Inc. 

MRID# 458706-01: Teixeira, D. (2002). RH-287 Technical – Determination of effects on 

vegetative vigor of three plant species. Springborn Smithers Laboratories.

MRID# 458706-02: Teixeira, D. (2002). TH-287 Technical – Determination of effects on 

seedling emergence and seedling growth of three plant species. Springborn Smithers 

Laboratories. 

MRID# 467807-29: Boeri, R.L., Wyskiel, D.C. and Ward, T.J. (2001). RRH-287 Technical: 

Bivalve Acute Toxicity Test (Embryo-Larval) with the Bay Mussel, Mytilus edulis. T.R. 

Wilbury Laboratories, Inc. 

MRID# 467807-30: Hahne, R. (2001). Toxicity of N-(n-ocyl) Malonamic Acid, PMN to the 

Unicellular Green Alga, Selenastrum capricornutum. ABC Laboratories, Inc.

MRID# 467807-31: Hahne, R. (2002). Acute toxicity of N-(n-ocyl) Malonamic Acid, 

Technical, PMN, to the water flea, Daphnia magna, under static conditions. ABC Laboratories, 

Inc. 

Page 71 of 77
MRID# 467807-32: Rhodes, J.E. (2002). Acute toxicity of N-(n-ocyl) Acetamide t the 

Rainbow Trout, Oncorhynchus mykiss, determined under static conditions. ABC Laboratories, 

Inc. 

MRID# 467807-33: Rhodes, J.E. (2002). Acute toxicity of N-(n-ocyl) Acetamide to the water 

flea, Daphnia magna, determined under static test conditions. ABC Laboratories, Inc.

MRID# 467807-34: Rhodes, J.E. (2002). Toxicity of N-(n-ocyl) Acetamide to the Unicellular 

green alga, Selenastrum capricornutum, ABC Laboratories, Inc.

MRID# 467807-36: Jones, A. and Aufderheide, J. (2003). RH-287 Technical: Chronic Toxicity 

in Whole Sediment to the Marine Amphipod, Leptocherirus plumulosus. ABC Laboratories, 

Inc.

MRID# 467807-38: Hughes, C. and Aufderheide, J. (2003). RH-287 Technical: Chronic 

Toxicity I Whole Sediment to the Marine Polychaete, Neanthes arenaceodentata. ABC 

Laboratories, Inc. 

MRID# 467807-40: Aufderheide, J.A. (2002). Acute toxicity of RH-287 Technical in whole 

sediment to the marine amphipod (Leptocheirus plumulosus). ABC Laboratories, Inc. 

MRID# 468163-04: Aufderheide, J. (2003). RH-287 Technical: Chronic toxicity in whole 

sediment to the freshwater midge, Chironomus riparius. ABC Laboratories, Inc. 

MRID# 468163-10: Hahne, R. (2002). Toxicity of N-(n-ocyl) Malonamic Acid, Technical, 

PMN to the saltwater diatom, Skeletonema costatum. ABC Laboratories, Inc.

Page 72 of 77
Appendix D Screening Level 

Down-the-Drain Analysis

The Down-the-Drain (DtD) module of E-FAST (Exposure and Fate Assessment Screening Tool), 

[version 2] was used to screen for the potential for aquatic organisms downstream of domestic 

wastewater treatment plants to be exposed to DCOIT and its degradates. The Down-the-Drain 

module uses daily per capita release of household wastewaters, stream dilution factors, and 

wastewater treatment plant removal efficiency to provide both high-end and median (average) 

time-averaged surface water concentrations of chemicals discharged by domestic wastewater 

treatment plants. The high-end scenario uses surface water concentrations downstream of 

domestic wastewater treatment plants based on the 10th percentile stream dilution factor (SDF); 

the average scenario uses surface water concentrations based on the 50th percentile SDF. SDF is 

defined as the ratio of the stream flow downstream of a wastewater treatment plant to the 

wastewater treatment plant flow. Inputs used to run the DtD module included concentrations of 

concern (COCs) for aquatic organisms, percent removal during wastewater treatment, and 

hypothetical wastewater treatment plant influent volumes. The results of the DtD module are 

expressed as number of days of exceedance of COCs for aquatic organisms. COCs are grouped 

into 3 categories: acute, endangered/listed, and chronic. Acute COCs for freshwater fish and 

invertebrates were derived by dividing LC50 values for freshwater organisms by 2. 

Endangered/listed COCs for freshwater fish and invertebrates were derived by dividing LC50 

values by 20. EC50 values for plants were used to establish acute COCs for plants. NOAEC 

values for plants were used to establish endangered/listed COCs for plants. Chronic COCs for 

freshwater fish and invertebrates are based on NOAEC values. For acute and endangered listed 

COCs, there may be potential concern for freshwater organisms if the COC is exceeded for 1 day 

or more. For chronic COCs, there may be potential concern for freshwater organisms if the COC 

is exceeded 20 days or more.

The Down-the-Drain module was first run using a high-end scenario to determine whether the 

model predicted exceedances of concentrations of concern. The average–case scenario was run 

when exceedences were observed with the high end scenario results. 

Page 73 of 77
Appendix E Product Chemistry

3(2H)-isothiazolone, 4,5-dichloro-2-octyl- product chemistry information is summarized in 

Table E1 (Source: MRIDs 40808501, and 41351601).

Table E1 – Product Chemistry of Octhilinone 

Guideline 

No.

Physical and Chemical 

Properties 3(2H)-isothiazolone, 4,5-dichloro-2-octyl830.1550 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 GC/MS

830.1900 Submittal of samples CBI

830.6302 Color tan to brown

830.6303 Physical State waxy solid

830.6304 Odor pungent aromatic

830.6313 

Stability to normal and 

elevated temperature, 

metals/metal ions 

Accelerated thermal stability testing of RH-287 Technical (55°C-3 

months) showed no evidence of decomposition of RH-25,287 or 

appearance of new impurities. By-products RH-27,610 and RH-34,227 

gradually decomposed to give unknown non-volatile products and < 0.05 

wt. % HCL.

830.6314 Oxidation/Reduction None

830.6315 Flammability Not applicable

830.6316 Explodability Not applicable

830.6320 Corrosion Characteristic RH-287 Technical is corrosive to steel and stainless steel. It is stored in 

fluorinated high-density polyethylene containers or glass containers.

830.7000 pH Not applicable

830.7050 UV/Visible Absorption Not reported

830.7100 Viscosity Not applicable

830.7200 Melting point 40-41 C

830.7220 Boiling point not applicable

830.7300 Density 1.28 g/ml at 25C (melted and solidified)

830.7370 Dissociation Constant Not applicable

830.7550 Partition coefficient (noctanol/water) 2.8

830.7840 Solubility in water 14 ppm

830.7860 Solubility in organic solvents Acetone 40%

Ethanol 35%

Page 74 of 77
Guideline 

No.

Physical and Chemical 

Properties 3(2H)-isothiazolone, 4,5-dichloro-2-octylCellosolve - 40%

830.7950 Vapor pressure 4.5 x 10-6 mm Hg

Page 75 of 77
Appendix F Public Comments 

Received on the Preliminary 

Work Plan

During the public comment period following posting of the Preliminary Work Plan to the docket, 

the agency received comments from the FIFRA Endangered Species Task Force (FESTF) and 

Dow Chemical Company. The following comments or requests were made.

Comment 1 (FESTF): The FESTF has noted that 3(2H)-Isothiazolone, 4.5-dichloro-2-octyl 

(DCOIT) has not had a complete endangered species determination performed to allow the 

agency to determine whether the uses have “no effect” or “may effect” federally listed species or 

their designated critical habitats. At such time as an endangered species evaluation is conducted 

by EPA, the data developed by FESTF, in response to the agency’s endangered species data 

requirements, will address species proximity to 3(2H)-Isothiazolone, 4,5-dichloro-2-octyl 

(DCOIT) uses.

EPA response: The agency will review the information submitted by the FESTF as part of the 

registration review process.

Comment 1 (Dow Chemical Company): The Application Rates (listed in Table 5) are not 

representative of the maximum use rates which appear on all of the EPA approved labels for 

DCOIT containing products.

EPA response 1: The values were corrected in Table 5.

Comment 2: The Application Rates (listed in Table 5) for the use of DCOIT in Architectural 

Paints and Marine Antifoulant Paints vary such that we suggest these be split into two separate 

entries.

EPA response 2: Table 5 has been updated to reflect two entries for the two paints. 

Comment 3: The Residential Handler Exposure Scenario (listed in Table 9) for the use of 

DCOIT in do-it-yourself antifoulant paints should be removed as DCOIT is only approved for 

use in paints solely for commercial applications.

EPA response 3: EPA confirmed that labels require antifoulant paint applications to be made by 

commercial applicators and are not expected to be used by residential users. The do-it-yourself 

antifoulant paints use scenario has been removed. The term “latex” has been added in section 

3.3.2 Residential Handler Exposure to “for the application of treated ‘latex’ paints and stains.” 

This scenario will have an exposure assessment done.

Page 76 of 77
Comment 4: EPA is required to evaluate all uses as part of registration review. Review of the 

wood preservative uses of DCOIT is premature and unnecessary.

EPA Response 4: The agency is expecting a wood pressure treatment study from the 

Antimicrobial Exposure Assessment Task Force (AEATF). Upon receipt, the agency will assess 

all uses of DCOIT in registration review.

Comment 5: The request for additional toxicity studies is not warranted given the wealth of 

information available for the isothiazolinone family of preservatives.

EPA response 5: DCOIT is one active ingredient in the isothiazolinone group. EPA encourages 

the submission of existing data and/or bridging rationale that a company believes satisfy the data 

needs identified.

Comment 6: DCOIT should be regulated as an irritant. 

Comment 7: The choice of uncertainty factors is not appropriate given the MOA of the 

isothizolinones. 

Comment 8: The choice of NOAEL is overly conservative in some instances.

Comment 9: Systemic NOAELs cannot be derived from isothiazolinones.

Comment 10: Rejection of guideline studies despite justified modification is not acceptable.

EPA responses 6, 7, 8, 9 and 10: DCOIT toxicity concerns mentioned in comments 6-10 above 

will be presented to the agency’s toxicity science advisory committee (TOXSAC) in the near 

future. Appropriate toxicological endpoints will be selected as part of risk assessments planned 

for this registration review.

 

Page 77 of 77