Docket Number: EPA-HQ-OPP-2012-0811

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Triclosan Registration Review Team

Human Health

William Hazel (now retired)

Timothy Leighton

Tim McMahon

Environmental Fate and Effects

James Breithaupt

Srinivas Gowda

Pat Jennings

William Erickson

Najm Shamim

Donna Randall

Risk Management

Sandra O’Neill

Rose Kyprianou

Office of General Counsel

Philip Ross

Andrea Medici
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Contents

List of Tables .................................................................................................................................. 4

List of Figures................................................................................................................................. 5

1 Introduction............................................................................................................................. 6

1.1 Statutory and Regulatory Authority ................................................................................. 6

1.2 Updates to the Work Plan................................................................................................. 7

1.3 Case Overview ............................................................................................................... 10

1.4 Chemical Identification and Properties.......................................................................... 10

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

1.5.1 Summary of Registered Uses.................................................................................. 12

1.5.2 Usage Information .................................................................................................. 14

1.6 Regulatory History ......................................................................................................... 15

1.6.1 Recent/Pending Regulatory Actions....................................................................... 16

1.6.2 Tolerance Information ............................................................................................ 19

1.7 Incidents......................................................................................................................... 19

1.7.1 Human Health ......................................................................................................... 19

1.7.2 Ecological ............................................................................................................... 19

2 Anticipated Data Needs ........................................................................................................ 20

3 Human Health Risk Assessment........................................................................................... 24

3.1 Existing Toxicological Endpoints.................................................................................. 24

3.2 Dietary Exposure............................................................................................................ 26

3.3 Occupational and Residential Exposures....................................................................... 26

3.3.1 Occupational Handler Exposures............................................................................ 27

3.3.2 Residential Handler Exposures............................................................................... 27

3.3.3 Residential Post-Application Exposures................................................................. 27

3.4 Aggregate and Cumulative Exposure............................................................................. 28

3.4.1 Aggregate Exposures.............................................................................................. 28

3.4.2 Cumulative Exposures............................................................................................ 28

4 Environmental Risk Assessment........................................................................................... 29

4.1 Environmental Conceptual Model Exposure Pathways................................................. 29

4.2 Ecological Effects Assessment....................................................................................... 31
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4.2.1 Mechanism of Action.............................................................................................. 31

4.2.2 Measures of Effect (Ecotoxicology Endpoints)...................................................... 32

4.3 Exposure Analysis Plan.................................................................................................. 33

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates ............................................ 33

4.3.2 Textile Manufacturing Monitoring Data................................................................. 34

4.3.3 Water Quality.......................................................................................................... 36

4.3.4 Screening-Level of Potential Risks to Aquatic Organisms from Pesticidal Uses of 

Triclosan Potentially Released to Wastewater Treatment Plants (WWTPs)........................ 37

4.4 Effects Analysis Plan ..................................................................................................... 38

5 Endocrine Disruptor Screening Program (EDSP)................................................................. 38

6 Next Steps............................................................................................................................. 39

7 References............................................................................................................................. 39

APPENDIX A: Toxicology Profile .............................................................................................. 41

APPENDIX B: Environmental Fate ............................................................................................. 60

APPENDIX C: Ecotoxicity Profile............................................................................................... 81

APPENDIX D: Environmental Fate and Ecotoxicity Data for Appendices B and C................. 104

APPENDIX E: Web-ICE and ECOSAR Results........................................................................ 119

APPENDIX F: For Ecological Assessment- Dioxins of Concern and Equivalency Factors ..... 129

List of Tables

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

Triclosan ............................................................................................................................. 9

Table 2 - Anticipated Registration Review Schedule..................................................................... 9

Table 3 - Chemical Identification of Triclosan............................................................................. 10

Table 4 - Physical-Chemical Properties for Triclosan.................................................................. 11

Table 5 - Triclosan Antimicrobial Use Summary......................................................................... 12

Table 6 – Studies Anticipated as Needed for Registration Review of Triclosan.......................... 21

Table 7 –Data Needs Required by the October 5, 2011 Data Call-In for the Triclosan RED...... 22

Table 8 - Toxicological Endpoints Used for the Triclosan RED.................................................. 24

Table 9 - Occupational Handler Exposure Scenarios for Triclosan ............................................. 27

Table 10 - Effects Endpoints for the Ecological Risk Assessment of Triclosan .......................... 32

Table 11—Textile Facility Characteristics During the Triclosan Monitoring Studies................. 35

Table 12—Triclosan and Methyl Triclosan Monitoring Data from Two Textile Manufacturing 

Facilities............................................................................................................................ 36
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Table 13 - Acute Toxicity Profile for Triclosan ........................................................................... 41

Table 14 - Non-Acute Toxicity Studies for Triclosan .................................................................. 42

Table 15 - Abiotic Degradation of Triclosan and Degradate Formation ...................................... 63

Table 16 - Metabolism of Triclosan with Formation of Degradates ............................................ 66

Table 17 - Effect of pH on the Ionization of Triclosan at 20 oC................................................... 68

Table 18 - Leaching and Adsorption-Desorption of Triclosan to Soil and Sediment .................. 69

Table 19 - Terrestrial Field Dissipation, Surface Runoff, Leaching, and Crop Uptake ............... 70

Table 20 - Environmental Monitoring Studies for Triclosan ....................................................... 73

Table 21 – Biological Field Monitoring of Aquatic Organisms................................................... 77

Table 22 WWTP Studies for Triclosan......................................................................................... 79

Table 23 - Textile Monitoring Facility Characteristics................................................................. 80

Table 24 - Textile Triclosan and Methyl Triclosan Monitoring Concentrations.......................... 80

Table 25 - Toxicity of Triclosan to Birds ..................................................................................... 81

Table 26 - Acute Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature ................................................................................................ 86

Table 27 - Acute Toxicity of Triclosan to Aquatic Animals from Open Literature Provided by 

OW.................................................................................................................................... 89

Table 28 - Chronic Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature ................................................................................................ 91

Table 29 - Chronic Toxicity of Triclosan to Aquatic Animals from Open Literature Provided by 

OW.................................................................................................................................... 93

Table 30 - Toxicity of Triclosan to Sediment Benthos from Submitted Studies.......................... 94

Table 31 - Toxicity of Triclosan to Aquatic Plants from Submitted Studies................................ 95

Table 32 - Toxicity of Triclosan to Aquatic Plants from Open Literature Reviewed by OW...... 96

Table 33 - Other Chronic Data on the Effects of Triclosan on Aquatic Organisms from Open 

Literature Reviewed by OW............................................................................................. 98

Table 34 - Acute Toxicity of Methyl Triclosan to Aquatic Organisms from Open Literature 

Provided by OW ............................................................................................................. 102

Table 35 - Dioxin Congeners of Toxicological Concern; Toxicity equivalency factors for 

mammals, birds and fish associated with each isomer are from U.S. EPA 2008b ......... 129

List of Figures

Figure 1 - Conceptual Model for Environmental Exposure from Treatment of Textiles with 

Triclosan ........................................................................................................................... 30

Figure 2 - Conceptual Model for Environmental Exposure from In-Service Use of Triclosan in 

Plastic Agricultural Film and Mulch................................................................................. 31
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1 Introduction

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

Plan (FWP) for triclosan. The FWP document explains what EPA's Office of Pesticide Programs 

knows about triclosan, 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 triclosan’s review.

The memorandum titled “Triclosan Response to Comments Memo” addresses public comments 

received during the comment period concerning the Preliminary Work Plan (PWP), which is

posted in the triclosan registration review docket (EPA-HQ-OPP-2012-0811). The memo is also 

posted in the triclosan registration review docket. This document makes final the work plan for 

the triclosan 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 U.S.

Environmental Protection Agency (USEPA, EPA, or the agency) based on scientific data

showing that they will not cause unreasonable risks to human health or the environment when

used as directed on product labeling. The registration review program is intended to make sure

that, as the ability to assess risk evolves and as policies and practices change, all registered

pesticides continue to meet the statutory standard of no unreasonable adverse effects to human

health or the environment. Changes in science, public policy, and pesticide use practices will

occur over time. Through the registration review program, the agency periodically reevaluates

pesticides to make sure that as change occurs, products in the marketplace can be used safely.

Information on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/.

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

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

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

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

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

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

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

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

Triclosan PWP was published on March 27, 2013 and the 60-day comment period ended on May 

28, 2013. 

Documents associated with this registration review can be viewed at www.regulations.gov in

docket EPA-HQ-OPP-2012-0811. Below is a summary of the issues relevant to this registration

review case.
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1.2 Updates to the Work Plan

Since the publication of the PWP, comments received resulted in a modification to the 

anticipated data needs identified in the Triclosan PWP. The anticipated data needs in the 

Triclosan PWP were modified for the following reasons: (1) open literature reviews were 

completed for some biotic metabolism fate studies resulting in removal of those anticipated data 

requirements; (2) waivers were submitted for two anticipated fate data requirements and were 

accepted as meeting data requirements for those anticipated data needs; and (3) the 850.3300 (or 

OECD 209) Activated Sludge, Inhibition Respiration (ASRI) study was added as an anticipated 

data requirement to support registration review of the textile/fabric use pattern.

The agency has made the following updates, divided into two categories, 1.) updates made as a 

result of the comments received concerning the PWP, and 2.) other updates:

Updates made as a result of the comments received to the triclosan PWP:

• Added the 850.3300 (or OECD 209) ASRI as an anticipated data requirement to support 

registration review of the textile/fabric use pattern.

• Clarified that EPA’s aggregate assessment to account for exposure to triclosan for

children under 6 years old will include the most up-to-date information provided the 

information complies with EPA’s Rule on Protections for Subjects in Human Research 

Involving Pesticides (Section 3.4). 

• Updated characterization of the ecotoxicity data that were available at the time of the 

2008 RED in Section 4.

• Added discussion about triclosan degradates to Section 4.3 Exposure Analysis Plan.

• Clarified the reasons that, in the case of pesticidal material preservative uses of triclosan, 

the environmental exposure pathway consisting of leaching of triclosan from in-service 

use of these materials with subsequent releases to wastewater was identified as a low 

likelihood of contributing to environmental risks of concern.

• Defined the term “PCE” under the figures in the Environmental Conceptual Model 

Exposure Pathways, Section 4.1.

• Changed Table 7 and 10 and the Benthic Invertebrate subsection of Appendix C to clarify 

that chronic, spiked-sediment benthic invertebrate testing for two freshwater and one 

estuarine/marine species is already required under the post-RED DCI (issued on October 

5, 2011) which is why they are not identified in Table 6 as additional anticipated data 

requirements for registration review.

• Corrected errors and missing data in the Web-ICE and ECOSAR Appendix E, and the 

resulting correction of the acute mysid value in the Ecotoxicity Profile Appendix C.

• Modified Section 4 Tables 11, 12, 23 and 24; and Appendices C, E, and D based on 

technical corrections of the textile effluent monitoring data, comment numbers 48-54 in 

the “Triclosan Response to Comments Memo.”

Other Updates:

• Correction of the anticipated registration review schedule (Table 2).
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• Deleted data requirements no longer anticipated to be required to support registration 

review since these are to be addressed in the submission of the remaining anticipated 

exposure data requirements: 

o 875.1600: Data Reporting and Calculations;

o 875.2900: Data Reporting and Calculations.

• Added Section 4.3.4 on the screening level down the drain analysis for in service use of 

materials preserved with triclosan.

• Clarified in the Exposure Analysis Plan that additional open literature regarding fate

would be identified and included.

• Updated Section 5 EDSP language to reflect that a second list of chemicals was identified 

for EDSP screening.

• The results of the water quality portion of Section 6.1.2 from the PWP were movedinto 

Section 4.3.3 of this FWP.

• Updated text and tables in Appendix B Environmental Fate to address completed review 

of waiver requests and the following open literature studies: Ying et al. (2007); Xu et al. 

(2009); Carr et al. (2011); Ying et al. (2011).

• Added a section on wastewater treatment studies in Appendix B, and moved wastewater 

studies out of the existing biotic fate tables to a separate table addressing wastewater 

treatment studies specifically, this is now Table 22.

• Updated tables in Appendix B Environmental Fate to include information on temperature, 

% purity and source information where it was missing, and moved incorrectly placed 

studies to the correct table.

• Split the references for citations in the Ecotoxicity Profile Appendix C into a separate 

Appendix D and added references for citations in the Environmental Fate Assessment 

Appendix B into the new Appendix D.

The agency received over 150 individual comments from 11 organizations and one private 

citizen concerning the materials included in the initial docket. Most comments were received 

from clean water agencies and clean water advisory boards voicing concerns about the EPA’s

approach to risk assessments for triclosan. These clean water organizations also made 

suggestions for refinements. These commenters were the Bay Area Clean Water Agencies 

(BACWA), the Central Valley Regional Water Quality Control Board, the San Francisco Bay 

Regional Water Quality Control Board, the California Stormwater Quality Association 

(CASQA), the Hampton Roads Sanitation District (HRSD), the National Association of Clean 

Water Agencies (NACWA), and Tri-Tac.

Vivimed Labs - a triclosan manufacturer, the Colgate Palmolive Company, and several other 

interested stakeholders also provided comments during the public comments period. 

A summary of the comments received and the agency’s responses are presented in the Triclosan 

Response to Comments Memo, which can be viewed at www.regulations.gov in docket EPAHQ-OPP-2012-0811.

Tables 1-2 below summarize 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 of Triclosan

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) Yes1 2008 Updated None

Dietary (drinking water) Yes1 2008 Updated None

Occupational Handler Yes 2008 Updated Dermal and inhalation exposure 

scenarios

Residential Handler No (see 3.3) 2008 None None

Residental PostApplication – Incidental 

Oral and Dermal

Yes1 2008 Updated None

Residential PostApplication – Inhalation No (see 3.3) N/A None None

Aggregate Yes1 2008 Updated None

Cumulative No (see 3.4.2) N/A None None

Tolerance Review Yes (see 1.5.3) N/A None None

Ecological Yes 2008 Updated

Acute mysid shrimp and 

mollusk; daphnid, mysid and 

fish life cycle tests; leaching 

from agricultural film and 

mulch,

2 activated sludge 

respiration inhibition

*Table 1 is a summary of the anticipated risk assessments and data needs for Registration Review. For data called in through the postRED DCI, see Table 7.

1 Dietary (food and drinking water) and residential exposure are part of the general population biological monitoring data from 

NHANES and will be accounted for in the anticipated aggregate assessment.

2 EPA has received a request to terminate the use of triclosan in agricultural films and mulches. If the cancellation order becomes 

effective and all product labels are amended to remove the use, this anticipated data should no longer be needed.

Table 2 - Anticipated Registration Review Schedule

Anticipated Activity Target Date1 Completion Date

Phase 1: Opening the Docket

Open Docket and 60-Day Public Comment Period for Preliminary 

Work Plan 2013-03 2013-03-27

Close Public Comment Period 2013-05 2013-05-28

Phase 2: Case Development

Issue Final Work Plan 2014-03 2014-04

Issue Data Call-In (DCI) 2015-03

Receive Data to be Considered in Risk Assessment 2017-03
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Open 30-Day Public Comment Period for Preliminary Risk 

Assessment 2018-09

Close Public Comment Period 2018-10

Phase 3: Registration Review Decision and Implementation

Open 60-Day Public Comment Period for Proposed Decision 2019-03

Close Public Comment Period 2019-05

Issue Final Decision 2019-09

Begin Post-Decision Follow-up 2019

Total (years) 6

1 The anticipated schedule will be revised as necessary (e.g., on any need arising under the Endocrine Disruptor 

Screening Program with respect to the active ingredients in this case).

1.3 Case Overview

The triclosan case (case #2340) contains one chemical, 2,4,4’-trichloro-2’-hydroxydiphenyl ether

(PC Code 054901) referred herein by its standard pharmaceutical name triclosan. Triclosan is a 

chlorinated aromatic compound. Triclosan was first registered by the United States on June 19, 

1969 as a bacteriostat. Presently, there are 9 registered products under PC Code 054901. There 

are no approved inert uses for triclosan. Triclosan is registered for use as a bacteriostat and 

fungistat in plastics, polymers, and textile products during the manufacturing process to impart 

antibacterial properties. It is also registered for use on hard non-porous surfaces of heating, 

ventilation and air conditioning (HVAC) exchange coils as a bacteriostat, fungistat and 

mildewstat. The agency completed a Reregistration Eligibility Decision (RED) Document for 

triclosan in September 2008. 

1.4 Chemical Identification and Properties

The chemical identification information for triclosan is listed in Table 3. Triclosan 5-Chloro-2-

(2,4-dichlorophenoxy) phenol (PC Code 054901) is a substituted diphenyl ether compound 

containing chlorine atoms in the 2, 4, and 4’ position. It includes both phenol and ether 

functional groups. 

Table 3 - Chemical Identification of Triclosan

Common Name Triclosan

Chemical Name 5-Chloro-2-(2,4-dichlorophenoxy) phenol

Classification Diphenyl ether; Polychloro phenoxy phenol

PC Code 054901

CAS No. 3380-34-5

Molecular Formula C12H7Cl3O2

Molecular Weight 289.541
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Molecular Structure:

The product chemistry information (source: MRIDs 42027902, 45358502, 42027904, 43022601, 

43277801 and 45358506) relevant to risk assessment for Triclosan is summarized in Table 4. 

Details of the fate properties are discussed in Appendix B.

Table 4 - Physical-Chemical Properties for Triclosan

Guideline 

Number Physical and Chemical Properties Triclosan

830.1550 Product identity and composition Refer to Table 3

830.1650 Description of Formulation Process Confidential Business Information (CBI)

830.6302 Color White crystalline powder

830.6303 Physical State Solid

830.6304 Odor Faint odor; slight aromatic/phenolic odor.

830.6313 Stability to normal and elevated 

temperature, metals/metal ions

Stable under ordinary conditions.

No thermal effect.

Stable when exposed to metals.

Triclosan exposed to zinc and zinc ions showed the 

same decrease in percent active ingredient (ai) as 

control.

Triclosan exposed to iron ions showed a greater 

decrease in percent ai than the control.

830.7000 pH Not applicable

830.7050 UV/Visible Absorption Degrades in sunlight

830.7200 Melting point 56.5°C

830.7220 Boiling point Triclosan is a solid and, therefore, has no boiling 

point. Decomposition temperature: >280°C

830.7300 Density 1.55 g/cm3 at 22°C

830.7370 Dissociation Constant in water pKa=8.14 at 20°C

830.7550 Partition coefficient (n-octanol/water) Log Kow 4.8 at 25oC 

830.7840 Solubility in water

Soluble in water at 0.012 g/l at 20 ̊C. Triclosan is 

considered sparingly soluble in water, moderately 

soluble in dilute alkaline solutions (1M sodium 

hydroxide). 

830.7860 Solubility in organic solvents

Readily soluble in most organic solvents such as 

ethanol, methanol, diethyl ether.

n-hexane 8.5 g/100 g at 25°C

acetone > 100 g/100 g at 25°C

830.7950 Vapor pressure 5.2 x 10-6 mm Hg at 25°C

N/A Henry’s Law Constant 5 x 10-9 (estimated) atm-m3/mole at 25°C
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1.5 Use/Usage Description

The products containing triclosan as the active ingredient (ai) include ready-to-use, 

pelleted/tableted, emulsifiable concentrate, and soluble concentrate formulations and 

impregnated materials. Concentrations of triclosan in these products range widely from 0.69% 

to ≥99%.

1.5.1 Summary of Registered Uses

Table 5 presents a summary of the registered uses of triclosan. There are currently 6 registrants 

and a total of 9 registered products. Triclosan is currently registered under FIFRA as a 

bacteriostat, fungistat, and mildewstat for use as a material preservative of products used in 

residential, public access, commercial, institutional and industrial premises. 

Except for the HVAC use product, triclosan is incorporated into or coated onto materials at 

manufacturing facilities by liquid pour and solid/powder pour (unless restricted to closed 

loading). For the HVAC use product, triclosan is sprayed as a fine mist onto exchange coils by a 

service contractor. This product is not available for use by home owners. There are no EPA 

registered products containing triclosan that can be applied directly by the homeowner; however, 

articles treated with triclosan are used by consumers and have the potential for post-application 

residential exposure. Triclosan-treated articles that may routinely be used in the residential 

market include, but are not limited to, material preservative uses in mattresses, clothing, bibs, 

tooth brush bristles, plastic toys, plastic cutting boards, garbage bags, paper, playground 

equipment, sponges, furniture, carpeting, rugs, flooring, floor waxes and sealers, and footwear. 

Table 5 - Triclosan Antimicrobial Use Summary

Use

Application

Method (liquid 

pour, solid/

powder pour)

Product 

Application

Rate

EPA 

Registration # 

and 

Formulation

Materials Preservative

Textiles: hosiery, nurses’ uniforms, laboratory coats, intimate 

apparel, surgical and examination gowns, scrub suits, wall 

coverings, upholstery fabric, drapery fabric, blankets, cubicle 

curtains, mattress pads and covers, sheets and pillow covers, 

mattress filling materials, pillow filling fibers and air filters.

Incorporation 2.00-5.00 % 10466-27

Synthetic & Cellulosic Sponges Incorporation 1.5-3.00 % 10466-42

Pigment Presscakes, Dispersions, Inks Incorporation 0.3-5.0 % 

Polymeric Systems Incorporation 2.00-5.00 % 

Fabrics1 Incorporation 0.8-1.5 %

Water-Base Emulsions/Adhesives Incorporation 0.8-1.5 %

Polymer Systems Incorporation 0.8-1.5 %

 1 Includes mattress covers, tickings and pads, pillow tickings, and hosiery.
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Use

Application

Method (liquid 

pour, solid/

powder pour)

Product 

Application

Rate

EPA 

Registration # 

and 

Formulation

Feathers & Down Incorporation 0.8-1.5 %

Apparel: aprons, athletic shirts, bibs, dresses, footwear (including 

socks & innersoles), general wear, gloves (consumer), gowns 

(medical & consumer), hosiery, intimate apparel, linings, running 

gear, sports apparel, trimmings, uniforms (service, medical, 

dental, sports), wet suits.

Incorporation 0.1-1.00 %

Construction & building materials: adhesives, awnings, bathtubs 42182-1

and bathtub enclosures, caulking (tub & tile), coatings (aqueous, 

solvent based; liquid, powder; metallic coating for plumbing 

fixtures, door handles, serving utensils, bed pans, floor drains, 

grease traps), concrete, flooring (concrete, epoxy, component 

fibers, & coatings), grout, handles & knobs, shower stalls, tile, 

wall coverings, whirlpools.

Incorporation 0.1-1.00 %

Films: agricultural and mulch films2, bags (blanket, garbage, 

garment, vacuum), curtains (window, shower, cubicle), liners 

(garbage, trays), wraps (silage).

Incorporation 0.1-1.00 %

Floor coverings: carpets, rugs, mats, sealer/wax components. Incorporation 0.1-1.00 %

Home furnishings: blankets, cloths, countertops, curtains, 

draperies, furniture & fabrics, linens (towels, sheets, pillowcases, 

etc.) mattress & pillow ticking, mattress pads, napkins, shower 

curtains.

Incorporation 0.1-1.00 %

Housewares: cutting boards, humidifier components, storage 

containers (for clothing, cosmetics, flowers, instruments, 

electronics, food & condiments), vacuum cleaner components.

Incorporation 0.1-1.00 %

Industrial: air filters, air filtration media, appliance housings, 

automotive interiors, brooms, brushes, buckets, carts, closure 

gaskets, conveyer belts, countertops (& covers), earplugs, 

garbage cans, hosing (non food; non-potable water transfer), 

janitorial supplies, mops, respirator mask components, tabletops, 

trays, wipes.

Incorporation 0.1-1.00 %

42182-1

Ice making equipment (water pans, piping, tubing, guards) Incorporation 0.1-0.5 %

Personal care products: bristles & handles of brushes (tooth, 

hair), combs, incontinence care products, razors. Incorporation 0.1-1.00 %

Sporting goods: boating/marine equipment, exercise & gym 

equipment, playground equipment. Incorporation 0.1-1.00 %

Miscellaneous: cards, currency, paper & paperboard (including 

menu materials & mulch), phones, toilets & toilet 

components/accessories, toys, wheels.

Incorporation 0.1-1.00 %

Textiles and Fabrics; Apparel trimmings and linings, aprons 

(food service, home), athletic wear, awnings (indoor and 

outdoor), bibs, blanket bags, blankets, brushes, carpets and rugs, 

Incorporation 0.1-2.00 % 86110-1

 2 EPA has received a request to terminate the use of triclosan in agricultural films and mulches. If the cancellation 

order becomes effective and all product labels are amended to remove the use, this table will be updated 

accordingly.
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Use

Application

Method (liquid 

pour, solid/

powder pour)

Product 

Application

Rate

EPA 

Registration # 

and 

Formulation

conveyor belts, covers for counter tops, covers for table tops, 

cubicle curtains, door and floor mats, dresses, exercise 

equipment, floor coverings, food services wipes (towels), 

furniture fabrics, garment bags, gloves (non-medical), gowns 

(medical & consumer), hair brushes, hosiery and socks, intimate 

apparel (underwear), janitorial brushes and brooms, linens 

(towels, sheets, pillowcases, mattress covers, etc.), mattress and 

pillow ticking, medical and dental clothing, mops, paper mulch, 

pillow and mattress stuffing, quilt fabric, running apparel, 

uniforms, shoes, shoe inner soles and linings, shower curtains, 

silage wraps, sporting team uniforms, sportswear, sweatshirts/tshirt, table clothes, napkins, tooth brush bristles, uniforms, wall 

coverings, wet suits, window curtain and draperies

Textiles and Fabrics; Incontinence care products (diapers and 

under pads) Incorporation 0.2-2.00 %

Polymers and plastics; adhesives, agricultural & mulch films2, 

combs & brushes, containers for cosmetics, conveyor belts, 

counter and table tops, currency, cushions, cutting boards, door 

& floor mats, exercise & gym equipment, floor coverings (wax, 

sealers, and coatings), flooring (concrete, epoxy, component, 

fibers, & coatings of urethane, epoxy etc.), floral containers, food 

distribution carts, food service trays, furniture coverings, 

furniture foam cushions, garbage bags and trash can liners, 

garbage cans, grease traps, medical & dental trays, menu 

materials, playground equipment & furniture, portable toilets, 

sponges (cellulose), shoe inner soles, storage containers (for 

clothing, instruments, electronics, food & condiments), tile (wall 

& floor) & grout, toilet seats, toilets and urinals, tooth brush 

handles, mop buckets toys, mops & mop components, pallets, 

paper and paperboard products, personnel cards (credit cards, 

driver's license, etc), tray liners, waste bins, wheel for medical 

carts, x-ray holders, metallic coatings for plumbing fixtures, door 

handles, serving utensils, bed pans, and floor drains

Incorporation 0.1-1.00%

Industrial Processes and Water Systems

HVAC coils Airless sprayer Not listed 82523-1

1.5.2 Usage Information

According to the Kline Biocides Report for 2004/2005 (Kline, 2005), the estimated volume 

consumption for triclosan in 2004 was 120,000 pounds and this entire amount was used in 

plastics. Triclosan makes up 16 percent of the estimated U.S. consumption of specialty biocides 

in plastics by volume and 6 percent by value. The consumption in plastics was forecasted to 

grow at an annual rate of 1.5 percent through 2009. 
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The Kline Report also notes that: “The exceptional growth previously expected for triclosan over 

the last five years has not realized due to several factors, including the EPA’s ruling on public 

health claims. This “Treated Articles Exemption” only allows for claims that biocides protect 

the integrity of the plastic, and disallows antimicrobial claims, for instance for an antimicrobial 

cutting board or countertop, unless that consumer product itself is registered with the EPA”

1.6 Regulatory History

The most recent comprehensive risk assessment performed by OPP on triclosan was conducted 

in support of the 2008 Reregistration Eligibility Decision (RED). As part of the RED, OPP 

performed a comprehensive review of the hazards, exposures and risks to human health and the 

environment resulting from the registered pesticidal uses of triclosan. In support of the RED an 

aggregate exposure risk assessment was performed for post-application residential exposures to 

triclosan using the National Health and Nutrition Examination Survey (NHANES) biological 

monitoring data collected by the Center for Disease Control and Prevention (CDC). NHANES is 

a program designed to assess the health and nutritional status of adults and children in the United 

States by examining a nationally representative sample of about 5,000 persons each year 

(http://www.cdc.gov/nchs/nhanes/about_nhanes.htm). The aggregate risk assessment took all

post-application exposures to triclosan into account including both EPA-registered antimicrobial 

uses and US Food and Drug Administration (FDA) - regulated uses such as triclosan-containing 

toothpaste, hand soaps, and deodorants. Based on available data at that time, the agency

concluded that total exposure to triclosan from all sources did not present risks of concern for 

human health. 

The agency conducted a qualitative environmental risk assessment as part of the RED using 

existing ecotoxicity studies, USGS monitored levels of triclosan found in waterways and 

consumer product environmental modeling. The agency determined that estimated 

concentrations of triclosan in surface water, when adjusted to represent concentrations from 

pesticidal uses only, did not exceed levels of concern for acute risk and were not likely to result 

in chronic risk. The agency issued a post-RED Data Call-In (DCI) requiring monitoring data on 

the effluent of manufacturing facilities using triclosan. These monitoring data, along with effects

data anticipated to be needed for the registration review, will be utilized to conduct a quantitative 

risk assessment during registration review. All currently registered pesticidal uses of triclosan 

were found eligible for reregistration in 2008. (Use of triclosan as a material preservative in paint 

was found ineligible. The registrant requested voluntary cancellation; the paint uses for triclosan 

will be removed from product labels prior to risk assessment, see section 1.6.1.) 

In response to the research on human health effects (US EPA / Office of Research and 

Development) that was ongoing at the time of the RED and public concern regarding triclosan, 

the agency decided to undertake another comprehensive review of triclosan under the 

Registration Review Program in Fiscal Year 2013. Since 2008, OPP has engaged in several key 
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efforts that will ensure that our review of triclosan is timely, scientifically sound and transparent, 

with appropriate public participation.

In the RED, the agency acknowledged scientific literature suggesting potential endocrine effects 

of triclosan and committed to examining the endocrine interactions of triclosan further. Since 

2008, the Office of Pesticide Programs has collaborated with the EPA’s Office of Research and 

Development (ORD) on the conduct of additional studies to investigate the endocrine effects of 

triclosan. In particular, ORD investigated the effects on the androgen, estrogen, and thyroid 

hormone systems using a variety of experimental approaches. The agency presented some of this 

information as part of a case study during the “Integrated Approaches to Testing and Assessment 

strategies (IATA): Use of New Computational and Molecular Tools” FIFRA Scientific Advisory 

Panel (SAP) consultation in May, 2011. The triclosan case study presented to the SAP was not a 

full risk assessment. 

As background information for the case study presented at the SAP, the agency also released an 

updated draft exposure assessment for triclosan that incorporated NHANES data that became 

available after the completion of the 2008 RED. The draft exposure assessment included 

NHANES data for ’05-’06 and ’07-’08 in addition to the ’03-’04 data that the agency utilized for 

the RED risk assessment. The agency has not developed any new conclusions regarding the 

impacts of triclosan on human health as a result of the case study or updated exposure 

assessment. Both the research conducted by ORD and the updated NHANES data will be taken 

into account during the comprehensive human health risk assessment that will be performed as 

part of the registration review of triclosan. Documents related to the SAP can be found at 

regulations.gov in docket EPA-HQ-OPP-2011-0284.

1.6.1 Recent/Pending Regulatory Actions

In March 2013 the agency received a request to amend triclosan labels for EPA registration 

numbers 42182-1 and 42182-7 to terminate the use in agricultural films and mulches. The 

amendment for EPA Reg. No. 42182-1 now incorporates the recommendations made in the 2008 

RED. EPA registration number 42182-7 is under review. EPA published a notice in the Federal 

Register announcing the receipt of the request pursuant to FIFRA section 6(f) on July 25, 2013, 

the notice can be found on regulations.gov in docket EPA-HQ-OPP-2013-0480-0001. In 2012 

and 2013 the EPA published Cancellation Orders for EPA Registration Numbers 2829-139, 

2829-145, 4822-429, 3090-165, 5383-127 and 10466-24 as a result of requests for voluntary 

cancellation. EPA Registration Number 83884-7 was cancelled in 2012.

Citizen’s Petition for a Ban on Triclosan

On January 14, 2010 Beyond Pesticides and Food & Water Watch submitted The Citizens 

Petition for a Ban on Triclosan to the U.S. Environmental Protection Agency (EPA).

The petition specifically requested that the agency take the following steps under each of the 

following statutes:
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FIFRA and FFDCA: (1) reopen the Reregistration Eligibility Decision (RED) (2) issue a 

notice of cancellation of the registrations of all products containing triclosan and (3) 

concurrently issue an emergency order to immediately suspend the existing triclosan 

registrations;

CWA: (1) impose technology-based effluent limitations, (2) establish health-based toxic 

pollutant water quality pretreatment requirements and (3) impose biosolids regulation for 

triclosan;

SDWA: (1) conduct a comprehensive assessment of the appropriateness of regulating 

triclosan under SDWA; and

ESA: (1) conduct a biological assessment and (2) engage in consultation with the 

Secretary of the Interior and the Secretary of Commerce.

All information submitted as part of the petition and during the comment period for the petition 

is available in docket EPA-HQ-OPP-2010-0548. The agency’s response will also be made 

available in that docket. The response to the petition’s requests for relief under FIFRA will be a 

final action by EPA independent of the registration review process. However, the petitioners, 

along with the public in general, will have multiple opportunities to participate in the registration 

review when they can contribute to the discussion of any scientific issues in relation to data 

developed since the RED, as well as any data that are submitted as part of this registration 

review.

Assessments by Other Regulatory Agencies

In December of 2013, FDA issued a proposed rule3 that would require manufacturers to provide 

additional data to support the safety and effectiveness of consumer antiseptic handwashes. For 

triclosan, FDA's focus is on the use by consumers on a regular basis in hand soaps and body 

washes. The FDA may require additional data to determine the potential for hormonal effects as 

well as the relevance of antimicrobial resistance to the consumer setting. However, the EPA does 

not anticipate the need to require additional endocrine data for the pesticidal uses of triclosan. 

Prior to release of the proposed rule, the EPA and the FDA closely collaborated on science and 

regulatory issues related to triclosan. FDA’s regulations implementing NEPA (21 CFR part 25) 

do not require an environmental assessment or environmental impact statement for FDA’s

proposed rule because it will not result in an increase in the use of the active ingredients that are 

 3 FDA’s proposed rule is available at: https://www.federalregister.gov/articles/2013/12/17/2013-29814/safety-andeffectiveness-of-consumer-antiseptics-topical-antimicrobial-drug-products-for
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the subject of the proposed rule, including triclosan. In the Preliminary Regulatory Impact 

Analysis for the proposed rule, FDA estimates that a benefit of the proposed rule would be a 

significant reduction in triclosan exposure. A decrease in human exposure from these uses would 

translate to a decrease in environmental impact.

In 2012, Health Canada and Environment Canada jointly published a preliminary assessment4 of 

the human health effects and environmental toxicity of triclosan. In Canada, triclosan is subject 

to regulation under the Pest Control Products Act (PCPA) (Canada 2002), the Food and Drugs 

Act (Canada 1985) and the Canadian Environmental Protection Act, 1999 (CEPA 1999) (Canada 

1999). In that preliminary assessment, triclosan exposure and risk were assessed from exposure 

to triclosan in consumer products treated with or containing triclosan (including, but not limited 

to, cosmetic products, treated textiles and food contact materials, such as cutting boards and 

countertops), drinking water contaminated with triclosan, breast milk, and contaminated 

household dust. Exposure of the general population to triclosan was characterized using the 

available biomonitoring data for triclosan from the US National Health and Nutrition 

Examination Surveys (NHANES). In the absence of Canadian-specific data for the general 

population, the biomonitoring data for the US population were used. Additional Canadian 

biomonitoring data were used to characterize the exposure of children under the age of 6 years to 

triclosan. Environmental exposures were assessed using measured data for concentrations of 

triclosan at WWTPs as well as in receiving surface water. Under CEPA 1999, Health and 

Environment Canada concluded that triclosan is not entering the environment in a quantity or 

concentration or under conditions that constitute or may constitute a danger in Canada to human 

life or health. However, it was concluded that with respect to the environment, triclosan “is 

entering or may enter the environment in a quantity or concentration or under conditions that 

have or may have an immediate or long-term harmful effect on the environment or its biological 

diversity.” Under the PCPA, Health Canada concluded that the use of pest control products 

containing triclosan in Canada does not pose an unacceptable risk to human health. While use of 

these products may contribute to environmental exposure to triclosan, given the registered uses 

and the life cycle of triclosan treated products (e.g., treated plastics, textiles, leather, paper and 

rubber), pest control products are not expected to contribute significantly to the risks to aquatic 

organisms. 

In 2009, the National Industrial Chemicals Notification and Assessment Scheme (NICNAS) 

within the Australia Government Department of Health and Ageing published a full risk 

assessment5 on the public health, occupational health and safety, and environmental effects of 

industrial uses of triclosan. Triclosan is not manufactured in Australia but is imported for use in 

the formulation of personal care and cosmetic products; therapeutic products; cleaning agents; in 

 4 Health Canada and Environment Canada’s preliminary assessment is available at 

http://www.chemicalsubstanceschimiques.gc.ca/plan/approach-approche/triclosan-eng.php 5 NICNAS’ risk assessment is available at:

http://www.nicnas.gov.au/Publications/CAR/PEC/PEC30/PEC_30_overview_PDF.pdf
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the treatment of textiles and in plastics manufacture; in the formulation of some oil-based paints; 

and in grouting material. That assessment concluded that under normal conditions of exposure 

for occupational workers and under normal conditions of use for residential populations, the risk 

of adverse effects from exposure to triclosan was low. It was acknowledged that repeated use of 

cosmetic products containing triclosan could lead to increased levels of exposure and thus to 

increased risk. With regard to environmental risk, it was concluded that there was no evidence 

that the use of triclosan was leading to development of triclosan-resistant bacterial populations or 

any increased risk to humans regarding antibiotic resistance. The assessment identified that 

triclosan is highly toxic to a number of freshwater aquatic organisms, with freshwater algae 

being the most sensitive species. The major environmental release of triclosan in Australia was 

identified as from wastewater treatment plants. As such, the assessment concluded that at 

current levels of use, the release of triclosan to the environment, the risk to fish and aquatic 

plants are at worst ‘marginal,’ but that adverse effects on algae could result from current levels in 

the environment. The application of biosolids containing triclosan to fields was identified as an 

area of concern for which more study of the effect of triclosan on microbial soil populations was 

identified. 

1.6.2 Tolerance Information

There are no tolerances or tolerance exemptions for triclosan. The need for tolerances or 

tolerance exemptions will be revisited during registration review.

1.7 Incidents

1.7.1 Human Health 

Eight triclosan related cases have been reported in OPP’s Incident Data System (IDS) for the 

time period spanning 2002 to 2011. Among the reported incidents, only one incident is 

considered triclosan-specific. The incident was reported to the agency in January of 2011 and 

involved symptoms in an individual who had hand washed a small amount of clothing with an 

anti-bacterial hand soap containing 0.15% triclosan. The individual reported symptoms including 

allergic reactions, headache, chemical taste in the mouth, complete loss of appetite, muscle 

twitches, and atrophy. The individual also reported that he had developed a full blown chemical 

sensitivity to triclosan. These symptoms were reported by the individual and no further details of 

the symptoms were provided, nor were these symptoms verified by a doctor or other health 

professional. The specific amount of triclosan to which the individual was exposed could not be 

determined from the description provided. 

1.7.2 Ecological

No incidents involving triclosan were reported in the following databases as of February 7, 2013: 

Ecological Incident Information System, version 2.1.1, the Aggregate Incident Data System, and 

the Avian Incident Monitoring System (AIMS)6. 

 6 http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm
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2 Anticipated Data Needs

Several studies were required as confirmatory data from the assessment of Triclosan in the RED. 

In addition to the already-required RED DCI data, the following studies as listed in Table 6 are

expected to be needed for the registration review of Triclosan. Table 7 outlines the data 

requirements required by the post-RED DCI issued on October 5, 2011. The agency anticipates 

reviewing any data received in response to the post-RED DCI as well as data requested for this 

registration review prior to conducting the registration review risk assessments for triclosan. 
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Table 6 – Studies Anticipated as Needed for Registration Review of Triclosan

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

Special Study1,2

Leaching from 

plastic agricultural 

mulch

TGAI 24 Environmental Fate, 

Ecological

Plastic/polymer agricultural 

mulch/film In-service use

850.1025

3,5

or 850.1055 Acute mollusk TGAI 12 Ecological Textile application, plastic/polymer agricultural mulch/film

Effluent discharge 

and in-service use, 

respectively

850.10353,5 Mysid acute TGAI 12 Ecological Textile application, plastic/polymer 

agricultural mulch/film

Effluent discharge 

and in-service use, 

respectively

850.13003,4,5 Daphnid Life Cycle 

study TGAI 12 Ecological Textile application, plastic/polymer agricultural mulch/film

Effluent discharge 

and in-service use, 

respectively

850.13503,5 Mysid life cycle TGAI 12 Ecological Textile application, plastic/polymer 

agricultural mulch/film

Effluent discharge 

and in-service use, 

respectively

850.15001, 3, 4,5 Freshwater fish full 

life cycle TGAI 24 Ecological Textile application, plastic/polymer agricultural mulch/film

Effluent discharge 

and in-service use, 

respectively

850.3300 or 

OECD 209

Activated Sludge,

Respiration 

Inhibition (ASRI)

TGAI 24 Environmental Fate, 

Ecological

Textile application, plastic/polymer 

agricultural mulch/film

Discharge to 

WWTP, effluent 

discharge

875.1200 Indoor Exposure, 

Dermal MP; EP 24 Occupational HVAC coils Airless sprayer

875.1400 Indoor Exposure, 

Inhalation MP; EP 24 Occupational HVAC coils Airless sprayer

1 The anticipated DCI will require that a protocol be submitted to the Agency for review and approval prior to conduct of the study. 2 EPA has received a request to terminate the use of triclosan in agricultural films and mulches. If the cancellation order becomes effective and all product labels 

are amended to remove the use, this anticipated data requirement should no longer be needed. 3 This study, previously held in reserve in the RED, is expected to be required for registration review (see Appendix C).
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4 An acute value is expected to be required for the same species used in the fish full life cycle test to allow calculation of an acute-to-chronic ratio (ACR) for use 

in predicting a chronic value for the most acutely sensitive freshwater species.

5

The anticipated DCI will require that testing under acidic, neutral and basic pH conditions be tested or alternatively, at a minimum that the study be conducted 

under acidic pH conditions that optimize the unionized state, which is generally considered the more bioavailable and toxic state, but which would also still be 

within the guideline biological pH range for the test species. With a pKa of around 7.9-8.1, at pH conditions of around 7.9-8.1 half of the triclosan is expected to 

be in the unionized and half in the ionized state.

Table 7 –Data Needs Required by the October 5, 2011 Data Call-In for the Triclosan RED

GLN Study Name Test Substance

Time Frame 

(Measured in 

months from 

DCI Receipt)

Risk Assessment(s) 

Data Will Support

Use Site(s) Triggering Data 

Requirement

Applicable Exposure 

Scenario

850.1730 Fish BCF PAIRA; TGAI 12 Environmental Fate, 

Ecological

Residential and public access 

premises; materials preservatives; 

aquatic non-food industrial use 

 

850.1710 Oyster BCF PAIRA; TGAI 12 Ecological

Residential and public access 

premises; materials preservatives; 

aquatic non-food industrial use

850.18501 Aquatic Food Chain 

Transfer PAIRA; TGAI 24 Ecological 

Residential and public access 

premises; materials preservatives; 

aquatic non-food industrial use 

SS-22 Chronic Sediment 

Toxicity MP; PAI; TGAI 24 Ecological

Residential and public access 

premises; materials preservatives; 

aquatic non-food industrial use

875.1200 Indoor Exposure, 

Dermal MP; EP 24 Occupational Materials preservatives Powder pour

875.1400 Indoor Exposure, 

Inhalation MP; EP 24 Occupational Materials preservatives Powder pour

875.1700 Product Use 

Information ALL 12 All All All

875.2300 Indoor Surface 

Residue Dissipation EP 24 Residential Material preservative use in plastics (toys) 

 

Mouthing plastic toys
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GLN Study Name Test Substance

Time Frame 

(Measured in 

months from 

DCI Receipt)

Risk Assessment(s) 

Data Will Support

Use Site(s) Triggering Data 

Requirement

Applicable Exposure 

Scenario

875.2700 Product Use 

Information ALL 12 All All All

875.2800 Description of Human 

Activity ALL 12 All All All

Source of post-RED DCI: EPA Docket EPA-HQ-OPP-2007-0513-0066, GDCI 054901-30197 1

Study held in reserve in the RED pending the outcome of surface water monitoring studies, the fish bioconcentration factor, and the oyster bioconcentration 

factor studies

2

Three chronic spiked-sediment studies are required, two with freshwater (midge and amphipod (Hyallela azteca)) and one with an estuarine/marine amphipod 

species.
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3 Human Health Risk Assessment

3.1 Existing Toxicological Endpoints

The endpoints listed in Table 8 were used in the human health risk assessments for the Triclosan 

RED. All information, including existing toxicology studies, valid scientific literature and the

studies that are expected to be required for registration review will be considered in the final risk

assessment for OPP.

Summary information on the interaction of triclosan with the endocrine hormone system,

including interaction with the thyroid, estrogen, and androgen hormone systems, was included in 

the 2008 RED. As part of the registration review, these data about interaction of triclosan with 

the endocrine system will be included in the risk assessment. 

With respect to human health risk assessments, the petition raised the issue of whether triclosan 

may result in human exposure to dioxins. The agency will evaluate available information to 

determine the extent to which this registration review will address potential human exposure to 

dioxins from triclosan.

Table 8 - Toxicological Endpoints Used for the Triclosan RED 

Exposure

Scenario

Dose Used in Risk 

Assessment 

Uncertainty factors 

for Risk Assessment Study and Toxicological Effects

Acute Dietary

(gen. pop.)

NOAEL = 30 

mg/kg

aRfD = 0.03 

mg/kg/day

Interspecies = 10x

Intraspecies = 10x

DB* = 1x 

UF = 100

Chronic Toxicity study in 

Baboons

MRID 133230

Acute Dietary

(females 13+)

No appropriate endpoint identified in the database

Chronic Dietary

(all populations)

NOAEL = 30 

mg/kg

cRfD = 0.03 

mg/kg/day

Interspecies = 10x

Intraspecies = 10x

DB* = 1x 

UF = 100

Chronic Toxicity study in 

Baboons

MRID 133230

LOAEL = 100 mg/kg/day, based 

on clinical signs of toxicity
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Exposure

Scenario

Dose Used in Risk 

Assessment 

Uncertainty factors 

for Risk Assessment Study and Toxicological Effects

Short-Term/ 

IntermediateTerm Incidental 

Oral (1-30 days; 

30 days- 6 

months)

NOAEL = 30 

mg/kg 

Interspecies = 10x

Intraspecies = 10x

DB* = 1x 

UF = 100

Chronic Toxicity study in 

Baboons

MRID 133230

LOAEL = 100 mg/kg/day, based 

on clinical signs of toxicity

Dermal (shortterm)NOAEL = 0.6 

mg/animal (100 

μg/cm2

) Interspecies = 3x

Intraspecies = 3x

DB* =1x

MOE = 10

14-day dermal toxicity study in 

the mouse 

MRID 44389708

LOAEL = 1.5 mg/kg/day, based 

on treatment-related dermal 

irritation at the treatment site and 

on increased liver weights

Dermal 

(intermediate 

term)

NOAEL = 40 

mg/kg

Interspecies = 10x

Intraspecies = 10x

DB* =1x

MOE = 100

90-day Dermal Toxicity in Rats

MRID 43328001

LOAEL = 80 mg/kg/day, based 

on increased incidence occult 

blood in the urine.

Dermal (longterm)NOAEL = 40 

mg/kg

Interspecies = 10x

Intraspecies = 10x

DB* =3x (lack of 

chronic dermal 

study)

MOE = 300

90-day Dermal Toxicity in Rats

MRID 43328001

LOAEL = 80 mg/kg/day, based 

on increased incidence occult 

blood in the urine.
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Exposure

Scenario

Dose Used in Risk 

Assessment 

Uncertainty factors 

for Risk Assessment Study and Toxicological Effects

Inhalation (all 

durations)

NOAEL = 50 

mg/m3 or 3.21 

mg/kg/day

Where mg/kg/day 

= ((0.0087 m3/hr 

* mg/m3 * 2 

hr/day) /0.271 

b.w. 

MOE = 1000

21-Day Inhalation Toxicity study 

in the rat

MRID 0087996

LOAEL = 0.115 mg/L, based on 

increased total leukocyte count 

and increased serum alkaline 

phosphatase

Cancer (oral) In accordance with the EPA Final Guidelines for Carcinogen Risk 

Assessment (March 29, 2005), the HED CARC classified triclosan as “Not 

Likely to be Carcinogenic to Humans”. 

UF = uncertainty factor, DB = database uncertainty [special sensitivity] factor, NOAEL = no observed adverse 

effect level, LOAEL = lowest observed adverse effect level, PAD = population adjusted dose (a = acute, c = 

chronic) RfD = reference dose, MOE = margin of exposure, LOC = level of concern, NA = Not Applicable

3.2 Dietary Exposure 

The use of products containing triclosan may result in indirect dietary exposure, i.e. exposure to 

food as a result of the use of triclosan in paper, adhesives, countertops, cutting boards, icemaking equipment, and conveyor belts. Exposure attributable to these uses was included in the 

aggregate assessment in the 2008 RED, and no dietary risks of concern were identified. Potential 

secondary (or indirect) dietary exposure will be included in the aggregate assessment for this 

registration review (see 3.4.1) based on the National Health and Nutrition Examination Surveys

(NHANES) biological monitoring data because these data reflect all exposures. 

3.3 Occupational and Residential Exposures

Representative occupational handler exposures were assessed in the 2008 RED for HVAC coil 

applications, painting scenarios, and pulp and paper mill use. Surrogate unit exposure data 

primarily from the proprietary Chemical Manufacturers Association (CMA) Antimicrobial 

Exposure Study (USEPA, 1999) and the Pesticide Handlers Exposure Database (PHED; USEPA, 

1999) were used to assess handler risk. Use of triclosan as a material preservative in paint was 

found ineligible. The registrant requested voluntary cancellation. The paint uses for triclosan will 

be removed from product labels prior to risk assessment; therefore, a residential handler 

exposure assessment is not anticipated to be needed for registration review. 
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3.3.1 Occupational Handler Exposures

EPA anticipates the need to conduct an occupational exposure assessment on the HVAC use and 

on open pouring/mixing of triclosan during material preservation.

Table 9 - Occupational Handler Exposure Scenarios for Triclosan 

Scenario Exposure 

Route(s) Duration

Occupational Exposures

Airless spray application to HVAC coils Dermal 

Inhalation Short, Intermediate 

Open pouring/mixing of powder during material 

preservation6

Dermal 

Inhalation 

Short, Intermediate, and Long 

Term

6

These data have already been required by the Post-RED DCI issued on October 5, 2011.

3.3.2 Residential Handler Exposures

Because residential handler exposure is not expected to occur, a residential handler exposure 

assessment is not anticipated for this registration review. 

3.3.3 Residential Post-Application Exposures

Residential post-application exposure is expected to occur from the use of EPA-registered 

products containing triclosan in textiles and fabrics (e.g., mattresses and clothing/bibs) and 

plastic products (e.g., toys, cutting boards, etc). Potential exposures also include EPA-registered 

uses where there is the possibility of indirect migration to food, including paper/pulp use, use in 

ice-making equipment, adhesives, cutting boards, and counter tops as well use in conveyer belts. 

In addition to EPA-regulated uses, residential post-application exposure is expected to occur 

from the FDA-regulated uses such as toothpaste, hand soaps, and deodorants. 

Residential post-application exposures for this registration review will be included in the 

aggregate assessment (see 3.4.1) based on the NHANES biological monitoring data. 

For the 2008 RED, EPA conducted the residential post-application exposure assessment for 

triclosan using the biomonitoring data available through NHANES. This approach was adopted 

by EPA because of the need to assess aggregate exposure that is expected from co-use of 

different consumer products containing triclosan. The NHANES monitoring data provides the 

most representative measure of aggregate exposures to daily use products. In the case of 

triclosan, population-based biological monitoring data are available to assess the co-occurrence 

of uses to develop an aggregate exposure assessment for ages 6 years and older. The populationbased biological monitoring data are the best predictor of aggregate exposure because not only 

are the data triclosan specific, they are also based on actual consumer use of the various triclosan 

products as they co-occur in practice and would include drinking water exposures as well. EPA 
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intends to use the latest available NHANES biomonitoring data for assessment of residential 

post-application exposures to triclosan in the registration review risk assessment. 

3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures

In examining aggregate exposure, EPA takes into account the available and reliable information 

concerning exposures to pesticide residues in food and drinking water, as well as nonoccupational (i.e. residential) pesticide exposures. An aggregate exposure assessment for 

triclosan was presented as part of the background documentation for the 2011 FIFRA SAP 

meeting using the NHANES database. 

For this registration review, EPA plans to conduct an aggregate assessment to account for 

exposure to triclosan from dietary and residential post-application exposures. The aggregate 

assessment will estimate risk based on the aggregated exposure of EPA and FDA uses using the 

NHANES biological monitoring data. The NHANES databases are a series of U.S. national 

surveys of the health and nutrition status of the non-institutionalized civilian population 

conducted by the Centers for Disease Control and Prevention (CDC). EPA believes the 

NHANES dataset provides the most comprehensive data on exposure to triclosan from all

sources (dietary and non-dietary as well as both EPA- and FDA-registered uses) and is the best 

dataset for estimating aggregate risk to triclosan. These data account for both indirect dietary 

exposures and exposures through drinking water more effectively than the standard models 

normally used by the agency to estimate exposures. However, because the NHANES 

methodology used to collect the samples from the general population does not allow EPA to 

distinguish the contribution of products regulated by EPA and those regulated by FDA, the 

residential assessment planned for registration review will estimate residential risk from all uses 

for triclosan. For the 2008 RED, NHANES data were available for triclosan only for the 2003-

2004 survey cycle. Subsequently, CDC has released the triclosan results for the 2005-2006, 

2007-2008, and 2009-2010 survey years. These data will be used for the registration review risk 

assessment of triclosan exposure. 

Although the aggregate exposures presented using the NHANES data are considered to include

all triclosan exposures, it does not include exposures to children under the age of 6 years old. 

Children under the age of 6 years exhibit unique activities that do not occur at older ages. 

Therefore, a separate estimate for children under 6 years old will be included in the registration 

review risk assessment and the most up-to-date information available will be considered 

provided the information complies with EPA’s Rule on Protections for Subjects in Human 

Research Involving Pesticides.

3.4.2 Cumulative Exposures

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 for 
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triclosan and any other substances. For the purposes of this registration review, therefore, EPA 

has not assumed that triclosan 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 the policy statements 

released by EPA’s Office of Pesticide Programs concerning common mechanism determinations 

and procedures for cumulating effects from substances found to have a common mechanism on 

EPA’s website at http://www.epa.gov/pesticides/cumulative/.

4 Environmental Risk Assessment

An ecological risk assessment was conducted for the RED (EPA 2008). Due to lack of available 

ecotoxicity data, that assessment only addressed acute risk to freshwater fish and invertebrates, 

and risks to aquatic plants and acute hazards to birds and mammals. Acute risks to 

estuarine/marine fish and invertebrates and chronic, reproductive risks to freshwater fish and 

invertebrates and estuarine/marine fish and invertebrates were not assessed. Exposure to aquatic 

organisms was based on monitoring data reported in the published literature, including U. S. 

Geological Survey (USGS) monitoring data for U. S. waterways, and from down-the-drain 

modeling. However, the waterway concentrations include all sources of triclosan, not just 

antimicrobial uses. To evaluate risks attributable to the antimicrobial pesticidal uses (rather than 

monitoring data which is primarily from personal care product uses or a mixture of these two), 

studies specifically designed to monitor the pesticidal textile and plastic manufacturing uses were 

called-in as part of the post-RED DCI (GDCI 054901-30197, October 5, 2011).

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

determination for triclosan. The ecological risk assessment planned during registration review 

will allow the agency to determine whether uses of triclosan have '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.

4.1 Environmental Conceptual Model Exposure Pathways

The conceptual model for the triclosan pesticidal use with potential environmental exposure is in 

Figure 1. The triclosan use scenarios with potential for environmental exposures of concern 

include material preservative uses which result in discharge to waste water treatment plants such 

as application to textiles. Discharge to WWTPs from leaching of triclosan during in-service use 

of treated textiles in homes, institutions, etc. is identified as not likely to contribute significantly 

to risks from the pesticidal uses of triclosan, as reflected by dashed lines in Figure 1. EPA 

performed a screening-level assessment to determine whether triclosan released to municipal 

wastewater treatment plants (WWTPs) from in-service uses of any materials preserved with 

triclosan (pesticidal uses) would be expected to lead to potential risks of concern to aquatic 
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organisms downstream of WWTPs7. No environmental exposure from the application of 

triclosan to plastic is expected because the label prohibits use in plastic manufacturing processes 

which would result in contact and transfer of triclosan with process water that would be 

discharged to a WWTP or to surface water. Of the in-service uses of plastic, the agricultural 

films and mulch have the potential to result in leaching to agricultural fields. None of the other 

material preservative uses and application methods (e.g., incorporation in concrete, adhesives, 

etc.) would result in contact and discharge of triclosan to wastewater. The conceptual models for 

uses with potential environmental exposure are in Figure 1and Figure 2.

8

PCEs (primary constituent elements) are those physical and biological features of a landscape that a species needs to survive and reproduce. 

For federally listed species, PCEs are listed with the critical habitat http://nctc.fws.gov/resources/knowledgeresources/Pubs9/critical_habitat00.pdf. 

Figure 1 - Conceptual Model for Environmental Exposure from Treatment of Textiles with 

Triclosan

 7 For more information about the screening level assessment assumptions, see Section 4.3.4 of this FWP. 8

EPA has received a request to terminate the use of triclosan in agricultural films and mulches. If the cancellation 

order becomes effective and all product labels are amended to remove the use, these conceptual models will be 

adjusted accordingly.

Stressor

Source

Receptors 

and Exposure 

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs related 

to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to 

habitat

Surface Water/Sediment

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake or sorption/cell, roots, 

leaves, 

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/ 

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals (terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Waste Water Treatment Plant (WWTP)

Key

Most likely

exposure pathway 

contributing to risk

Low likelihood of 

contributing to risk

WWTP 

microorganisms

Uptake or 

sorption

Population

Respiration 

inhibition

Textile (Exhaust, Padding) 

Treatment Process

Facility Drain

In-Use Service of 

Treated Textiles

Washing/Leaching
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PCEs (primary constituent elements) are those physical and biological features of a landscape that a species needs to survive and reproduce. 

For federally listed species, PCEs are listed with the critical habitat http://nctc.fws.gov/resources/knowledgeresources/Pubs9/critical_habitat00.pdf.

Figure 2 - Conceptual Model for Environmental Exposure from In-Service Use of Triclosan 

in Plastic Agricultural Film and Mulch

4.2 Ecological Effects Assessment

Ecological effects data are used as measures of direct and indirect effects to biological receptors.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the

available open literature will be used to evaluate the potential direct and indirect effects of

triclosan to aquatic and terrestrial receptors. Current selected ecotoxicological endpoints are

summarized in Table 10. A more detailed description of the ecotoxicity studies is provided in

Appendix C.

4.2.1 Mechanism of Action

IFDA (2008) identifies that triclosan has two mechanisms of action. One mechanism is via 

insertion into bacterial cell membranes and disruption of membrane activities without causing 

leakage of intracellular components. The second mechanism of action is inhibition of bacterial 

fatty acid synthesis at the enoyl-acyl carrier protein reductase step. Fatty acid synthesis is critical 

Stressor

Source

Receptors 

and Exposure 

Routes

Attribute

Change(s)

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Modification of PCEs related 

to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to 

habitat

Surface Water/Sediment

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Ingestion Ingestion

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake or sorption/cell, roots, 

leaves, 

Piscivorous*

Invertebrates

Vertebrates

Phytoplanktivore/ 

Herbivore

Invertebrates

Vertebrates

*As used here this term refers to animals (terrestrial or aquatic) that eat not just fish but any aquatic animal (e.g., amphibians, mollusks, crustaceans, etc.)

Ingestion

Key

Most likely

exposure pathway 

contributing to risk

Low likelihood of 

contributing to risk

In-Service Use of Plastic Agricultural Mulch Treated

Leaching and Run-off
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for building of cell membranes and reproduction. This enzyme is found in bacteria, fungi, and 

some plants. In algae triclosan has been observed to compromise lipid biosynthesis, cell 

membrane integrity and photosynthesis.

4.2.2 Measures of Effect (Ecotoxicology Endpoints)

Current selected ecotoxicological endpoints for conducting the risk assessment are provided in 

Table 10. All available ecotoxicity endpoints from studies submitted by registrants are tabulated 

in Appendix C. The agency recognizes that there are additional data available on triclosan 

effects in the open literature. Part of the analysis plan includes a literature search and review of 

such data for inclusion in the risk assessment as needed. The agency uses the most sensitive 

acceptable toxicity values for assessing risk to each receptor group. Endpoint data gaps are 

indicated.

No endpoints were selected for dioxin or methyltriclosan transformation products. From a 

preliminary examination of which dioxins are formed from triclosan in chlorinated waters (2,7-

dibenzodichloro-p-dioxin; 2,8-dichloro-p-dioxin; 1,2,8- and 2,3,7-trichlorodioxins and 1,2,3,8-

tetrachlorodioxin), they are not among congeners of toxicological concern (see Appendices B

and F) and no endpoints were selected for the assessment. Additionally, methyltriclosan was not 

detected in effluent monitoring studies for textiles (<1.9 nanograms per liter (ng/L)) and 

therefore no endpoints are included. 

Table 10 - Effects Endpoints for the Ecological Risk Assessment of Triclosan 

Receptor Group Surrogate 

Species Risk Scenario Toxicity Endpoint Comment

Reference/

Study 

Classification

Freshwater fish

Fathead 

minnow Acute 96-h LC50 = 288a μg ai/L 43969301

Rainbow 

trout Chronic Fish full life cycle data 

required

An acceptable 

acute 96-h LC50

study is expected 

to be required for 

the species used in 

the fish full life 

cycle to allow 

calculation of an 

ACR

Freshwater 

invertebrates Waterflea Acute 48-h EC50 = 390 μg ai/L 430460-02

Chronic Data required

Freshwater benthic 

invertebrates Midge Chronic NOAEC >100 mg ai/kg 475866-01

Estuarine/marine 

fish

Sheepshead 

minnow

Acute 96-h LC50 = 716,000 μg 

ai/L Web-ICE v3.1

Chronic Data anticipated to be 

required

Plan to model 

from acute-tochronic ratios 

(ACRs).
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Receptor Group Surrogate 

Species Risk Scenario Toxicity Endpoint Comment

Reference/

Study 

Classification

Estuarine/marine 

invertebrates

Mysid 

Shrimp 

Acute Data anticipated to be 

required

Chronic Data anticipated to be 

required

Oyster Acute Data anticipated to be 

required

Estuarine/marine 

benthic 

invertebrates

Chronic

No data in addition to 

that already required

under the post-RED DCI 

are anticipated

Algae and 

Cyanobacteria Green algae

EC50 0.7 μg ai/L

Orvos et al. 2002

NOAEC 0.5 μg ai/L

Aquatic vascular 

plants Duckweed

EC50 EC50 >62.5 μg ai/L 44422801

NOAEC Not determined

Birds Mallard

Acute LD50 = 822 mg ai/kg bw 43022602

Chronic Not required NA

Mammals Rat

Acute LD50 >5000 mg/kg 43206901

Chronic NOAEC = 50 mg ai/kgbw/day 40623701

Nontarget insects Acute Not required N/A

a Value reported here was calculated using mean measured concentration. Because triclosan was not stable during 

the study, a value using concentrations measured at the end of the exposure period will be evaluated.

4.3 Exposure Analysis Plan

During the risk assessment phase of registration review, the agency will review environmental 

fate and exposure from submitted guideline studies, open literature, and government databases. 

Impacts on the understanding of the fate of triclosan and its major degradates, and the exposure 

approach and risk assessment approach described in this work plan will be taken into 

consideration during the risk assessment phase of registration review.

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates

In order to address the risk hypothesis, estimates of environmental exposure will be based on the 

use for textile treatment (which consists of discharge from textile manufacturing sites) and the 

in-service use of agricultural mulch conceptual models. For in-service use of agricultural mulch 

impregnated with triclosan, PRZM/EXAMS will be used to estimate runoff and loading to 

surface water from agricultural fields covered with agricultural mulch impregnated with 

triclosan9

. No information on the leach rate from plastic agricultural mulch is available for use 

 9 EPA has received a request to terminate the use of triclosan in agricultural films and mulches. If the cancellation 

order becomes effective and all product labels are amended to remove the use, this section will be updated 

accordingly.
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in PRZM modeling. Conservative estimates of triclosan leaching from plastic, such as 100% 

leaching, will be used unless information on leaching from plastics is submitted or found from 

open literature to refine estimates of leaching. In the 2008 RED, surface water monitoring data 

was used to characterize risk from pesticidal uses, but the available monitoring data was not 

specifically designed to identify exposure specifically from pesticidal (e.g., material 

preservative) uses and more likely reflected contributions from FDA-regulated uses. Monitoring 

data specific to material preservative uses were called-in as part of the post-RED generic data 

call-in (GDCI-054901-30197). These data have been submitted and found to be acceptable for 

use in the risk assessment. This monitoring data will be used to characterize exposure for use in 

the registration review. A discussion of the monitoring data for the textile manufacturing use is 

discussed in Section 4.3.2.

4.3.2 Textile Manufacturing Monitoring Data

In accordance with the analysis performed for the re-registration of triclosan, EPA required

monitoring data on triclosan contained in effluents from textile manufacturing facilities as part of 

the post-RED DCI. In support of this request, select direct-discharging (holding valid NPDES 

Permits) textile manufacturing facilities, using triclosan as a material preservative, were used to 

determine the concentration of triclosan in textile manufacturing effluent. ENVIRON

International Corporation on behalf of Microban International, Ltd conducted monitoring in 

2012. Two textile facilities were chosen to collect data on the concentrations of triclosan and 

methyl triclosan present in their effluent after triclosan was applied to textiles using the 

exhaustion process. This process uses a dye-bath (i.e. jet machine) to apply triclosan and other 

ingredients to textiles at high temperature. The spent or remaining solution from the exhaustion 

process is discharged to on-site wastewater treatment plants before the resulting effluent is 

discharged to surface waters. The discharge to surface waters at these facilities is conducted 

under National Pollutant Discharge Elimination System (NPDES) permits. Sampling intervals 

and frequencies were determined based on facility production operations, wastewater treatment 

operations, and the hydraulic retention times for the unit processes, ensuring that the effluent 

samples would be representative of facility effluent during triclosan-impregnation operations. 

Additional WWTP process parameters collected during the sampling periods provided support 

that WWTPs were operating normally during sampling periods. The triclosan use pattern and 

WWTP characteristics for these two facilities are summarized in Table 11. Results from the 

monitoring, which are summarized in Table 12 will be used to characterize discharge and 

environmental exposure from the textile material preservative use. The estimated in-stream 

concentrations for these specific facilities were based on the facilities’ permitted discharge flow 

rate and the receiving water body low-flow condition (specifically 7Q10 flow10).

 

10 "The streamflow that occurs over 7 consecutive days and has a 10-year recurrence interval period, or a 1 in 10

chance of occurring in any one year. Daily stream flows in the 7Q10 range are general indicators of prevalent 
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Table 11—Textile Facility Characteristics During the Triclosan Monitoring Studies

Characteristic Facility # 1 Facility # 2 Notes

Triclosan application 

pattern during study Intermittently used Constantly used --

Number of days each 

facility was processing 

textiles in study period

15 11

Amount (lbs) of triclosancontaining formulation

applied in study

327 636 --

Number of influent streams 

into WWTP

1 textile process WW

1 non-contact cooling 

water WW (0.037 MGD)

1 remediation 

groundwater (0.005 

MGD)

1 chemical (nutrientsdehydrated) influent to 

aeration lagoon

1 textile process WW

1 utility WW (0.144 

MGD)

1 stormwater 

collection system 

(0.021 MGD)

1 chemical (nutrients60 mL/min) influent 

to aeration lagoon

WWTP effluent flow rates 

(MGD)

Min: 0.09

Avg: 0.21

Max:0.7

Min:1.04

Avg: 1.47

Max: 1.81

--

Hydraulic retention time 

(days)

Min: 13

Avg: 43

Max: 100

Min:6

Avg: 7

Max: 10

--

Aeration lagoon(1) volume 

(MG) 2.25

3.8 each

(two lagoons in 

series)

Facility #2 has an 

equalization basin prior to 

flow into aeration lagoons

Aeration lagoon mixedliquor suspended solids 

concentration

2500 mg/L NR

Clarifier volume (MG) 0.147 each

(2 parallel)

0.542 each

(2 parallel)

Facility #2 has a flash 

mixing/flocculation tank 

for chemical coagulation, 

if needed, prior to clarifier

Polishing pond volume 

(MG) 6.5 --

Post-aeration tank (MG) -- 0.033382

Avg: average; MG: million gallons; MGD: million gallons per day; Max: maximum; Min: minimum; NR: 

not reported; WW: wastewater

(1) Biological treatment stage.

 

drought conditions which normally cover large areas. 7Q10 values are also used by the State for regulating water 

withdrawals and discharges into streams." (USGS)
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Table 12—Triclosan and Methyl Triclosan Monitoring Data from Two Textile 

Manufacturing Facilities

Facility

Triclosan Concentration

(ng/L)

Methyl 

Triclosan 

(ng/L)

Whole Effluent(1) Effluent Supernatant(2) In-Stream(4)

Avg Max Med Avg Max Med Avg Max Max

No. 1 99 190 80 73.6 130 63 3.2(3) 6.1(3) ND(5)

(1.8-1.9)

No. 2 138 180 130 88.8 110 84 33.1 43.2 ND (1.8)

(1) Five consecutive, 24-hour composite effluent samples collected from each facility’s WWTP effluent 

channel. (2) Supernatant from sample subjected to centrifugation at 100,000 ms-2

. (3) In-stream wastewater concentration (IWC) factor of 3.2% (dilution ratio of 31.25) as per NPDES 

permit.

(4) IWC factor of 24% (dilution ratio of 4.167) as per NPDES permit.

(5) Values in parentheses represent Method Detection Limits (MDLs) for the samples.

4.3.3 Water Quality

Triclosan is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act, based on information provided at the agency’s National 

Pesticides Cause of Impairment of Waters website (searched February 22, 2013)11,12. In 

addition, no Total Maximum Daily Loads (TMDL) have been developed for triclosan, based on 

information provided at the agency’s National Pesticide TMDL web site (searched February 22, 

2013)13. More information on impaired water bodies and TMDLs can be found at 

http://www.epa.gov/owow/tmdl/. 

From a preliminary examination, the dioxins formed from triclosan in chlorinated waters (2,7-

dibenzodichloro-p-dioxin; 2,8-dichloro-p-dioxin; 1,2,8- and 2,3,7-trichlorodioxins and 1,2,3,8-

tetrachlorodioxin), are not among congeners of toxicological concern (see Appendices B and F). 

Dioxin congeners considered of environmental toxicological concern are listed in Table 34. 

Because the dioxin congeners are not those of concern, a search of impaired waters due to 

dioxins of environmental concern was not performed for triclosan.

 11 . http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 12 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T#causes_303d 13http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES
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4.3.4 Screening-Level of Potential Risks to Aquatic Organisms from Pesticidal Uses of 

Triclosan Potentially Released to Wastewater Treatment Plants (WWTPs)

EPA performed a screening-level assessment using E-FAST (USEPA 2007) to determine 

whether triclosan that might be released to municipal WWTPs from pesticidal in-service uses of 

materials treated with triclosan would be expected to lead to potential risks to aquatic organisms 

downstream of WWTPs. This screening-level assessment assumes that: (1) the entire maximum 

annual consumption volume of triclosan is released to WWTPs; (2) removal of triclosan during 

wastewater treatment would be 80 percent; and (3) concentrations of concern (COCs) based on 

effects endpoints for aquatic organisms (Table 10 and Appendix C) that reflect the highest 

potential for toxicity. This screening level assessment demonstrates that even if the entire 

maximum annual consumption volume of triclosan was released to municipal WWTPs over a 

one-year period, there would be no potential risks to listed and nonlisted aquatic organisms 

downstream of these WWTPs.

The results of this screening-level analysis based on a high-end scenario assuming 80 percent 

removal of triclosan during wastewater treatment and 54,000 kilograms per year of triclosan 

entering municipal WWTPs are as follows: 

• At a COC of 0.5 ppb, which is a chronic COC representative of listed aquatic nonvascular plants, the COC is exceeded 17 days per year;

• At a COC of 0.7 ppb, which is a chronic COC representative of non-listed aquatic nonvascular plants, the COC is exceeded 9 days per year;

• At a COC or 14.4 ppb, which is an acute COC representative of listed freshwater fish, the 

COC is exceeded for less than 1 day per year (i.e., 0.007).

COCs for other measurement endpoints in Table 10 would be higher and the corresponding 

number of days of exceedance would be even lower than the COCs examined in this screeninglevel analysis. If an acute COC for a listed or nonlisted aquatic organism is exceeded on 1 day or 

more, then potential acute risks to aquatic organisms in the receptor group the organism 

represents are indicated. If a chronic COC for a listed or nonlisted aquatic organism is exceeded 

on 20 days or more, then potential chronic risks to aquatic organisms in the receptor group the 

organisms represents are indicated. Consequently, these results demonstrate negligible potential 

for acute and chronic risks to aquatic organisms downstream of municipal WWTPs to which 

pesticidal triclosan could be released.

Note that the input value of 54,000 kilograms of triclosan per year assumed for WWTP influent 

volume is a vast overestimate of the amount of pesticidal triclosan that would be expected to 

enter a wastewater treatment plant. First, not all of the antimicrobial uses of triclosan listed in 

Table 5 would have the potential to come in contact with water that would eventually be released 

down-the-drain to a municipal WWTP. In addition, it is highly unlikely that 100 percent of the 

triclosan in all of these products would leach out of these products over a 1-year period. The 
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value used as an input for the wastewater treatment plant influent volume of the DtD model was 

54,000 kilograms triclosan per year (Kline, 2005). This estimate is based on the estimated 

volume consumption of triclosan reported in 2004 (i.e., 120,000 pounds). The percent removal 

of triclosan during wastewater treatment was assumed to be 80 percent based on a study by Lee 

et al. (2003). 

Concentrations of concern (COCs) for aquatic organisms that were used in this screening-level 

assessment are based on measurement endpoints in Table 10 for which the toxicity of triclosan 

was highest. These include: (1) the NOAEC for green algae of 0.5 ug/L, which is the highest 

chronic toxicity value for any nonlisted aquatic species; (2) the EC50 for green algae of 0.7 ug/L, 

which is the highest chronic toxicity value for any listed aquatic species; and (3) the COC of 14.4 

ug/L, which is the acute COC for listed freshwater fish that is derived from the LC50 of 288 ug/L 

determined for the fathead minnow, a representative freshwater fish species. (COCs for acute 

toxicity for non-listed aquatic organisms are determined by dividing the LC50 by 2 and COCs for 

acute toxicity for listed aquatic organisms are determined by dividing the LC50 by 20. COCs for 

chronic toxicity are based on the measurement endpoint, which is usually a NOAEC.) 

4.4 Effects Analysis Plan

Open literature studies for effects data on triclosan and its major degradates will be identified

through EPA’s ECOTOXicology (ECOTOX) database14, which employs a literature search

engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The

ECOTOX database will be searched when the risk assessment for triclosan is prepared.

Endpoints more sensitive than those already selected will be reviewed for use in the risk 

assessment.

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 

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

taxonomic groups. As part of its 2008 reregistration decision for triclosan, 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), triclosan is subject to 

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

 14 http://cfpub.epa.gov/ecotox/ 

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.
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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, 201315 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 list of 

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

website16.

6 Next Steps

EPA will issue a DCI to all registrants of triclosan products requiring submission of the 

anticipated data listed under the “Anticipated Data Needs” section of this document. The agency 

expects to issue the DCI by March 2015. The agency will conduct the human health and 

environmental fate and ecological hazard assessments necessary to determine whether products 

that contain triclosan continue to meet the FIFRA standard for registration. 

7 References

Ellis DD et al; Arch Environ Contam Toxicol 11: 373 - 82 (1982). Environmental Protection

Agency. High Production Volume Information System (HPVIS).

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

Lee, H.B., K. Sarafin, T.E. Peart, and M.L. Svoboda. 2003. Acidic Pharmaceuticals in 

Sewage—Methodology, Stability Test, Occurrence, and Removal from Ontario Samples. 

Water Qual. Res. J., Canada (38(4): 667-682.

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

chemicals. 16 http://www.epa.gov/endo/
Docket Number: EPA-HQ-OPP-2012-0811

Page 40 of 130

Miller et al; Estogenic Activity of Phenolic Additives Determined by an In Vitro Yeast Bioassay,

Environmental Health Perspectives, Volume 109, Number 2, pp. 133-138, February.

2001.

Proia, L., S. Morin, M. Peipoch, A.M. Romani, and S. Sabater. 2011. Resistance and recovery 

of river biofilms receiving short pulses of triclosan and diuron. Sci. Total Environ. 

409(17): 3129-3137.

Routledge and Sumpter; Structural Features of Alkylphenolic Chemicals Associated with

Estrogenic Activity, Journal of Biological Chemistry, Volume 272, Issue 6, pp 3280-

3288, February 7, 1997.

Soto, AM et al: The E-Screen Assay as a Tool to Identify Estrogen - An Update on Estrogenic

Environmental Pollutants, Environmental Health Perspectives, Vol. 103, Supplement 7,

pp 113-122, October 1995

Tollefsen et al; Estrogenicity of Alkylphenols and Alkylated Non-Phenolics in a Rainbow Trout

(Oncorhynchus mykiss) Primary Hepatocyte Culture. Ecotoxicology and Environmental

Safety 71, pp 370-383, 2008.

United States Environmental Protection Agency (USEPA). 2007. Exposure and Fate 

Assessment Screening Tool (E-FAST), 

http://www.epa.gov/opptintr/exposure/pubs/efast.htm.

United States Food & Drug Administration (FDA). 2008. Nomination Profile Triclosan [CAS 

3380-34-5] Supporting Information for the Toxicological Evaluation by the National 

Toxicology Program. July 2008.

Yamasaki et al; Immature Rat Uterotrophic Assay of 18 Chemicals and Hershberger Assay of 30

Chemicals. Toxicology 183, pp 93-115, 2003.
Docket Number: EPA-HQ-OPP-2012-0811

Page 41 of 130

APPENDIX A: Toxicology Profile

Hazard/Toxicity

Acute Toxicity for Product Labeling

A complete database of acute toxicity data for triclosan was available to the agency at the time 

the RED was written. A summary of the findings, which are detailed in the RED, is included 

below in Table 13. Acute toxicity studies in experimental animals with technical grade triclosan 

show that by the oral and dermal routes, triclosan is of low acute toxicity (Toxicity Category IV; 

MRIDs 43206501 and 94044). By the inhalation route of exposure, triclosan was assigned 

Toxicity Category II for acute exposures and is thus of higher acute toxicity by inhalation 

exposure than by oral or dermal exposures (MRID 42306902 and 43310501). Triclosan 

produces moderate irritation to the eyes (MRID 94045) and skin (MRID 42306903) with a 

Toxicity Category III assigned for both for acute exposures. Triclosan was not a dermal 

sensitizer in guinea pigs using the Buehler method (MRID 43206502).

Table 13 - Acute Toxicity Profile for Triclosan

Guideline 

Number

Study Type/

Test substance (% ai)

MRID Number/

Citation Results Toxicity Category

870.1100

(§81-1)

Acute Oral- Rat Triclosan 

(99.7% ai) 43206901 LD50: >5000 mg/kg IV

870.1200

(§81-2)

Acute Dermal- Rabbit

Triclosan (97% ai) 94044 LD50: >9300 mg/kg IV

870.1300

(§81-3)

Acute Inhalation- Rat

Triclosan (100.5% a.i.)

42306902, 

43310501 LC50: >0.15 mg/L II

870.2400

(§81-4)

Primary Eye IrritationRabbit

Triclosan (97% ai)

94045 moderately irritating II

870.2500

(§81-5)

Primary Dermal IrritationRabbit

Triclosan (% ai not 

provided)

42306903 PII: 3.5 at 72 hours III

870.2600

(§81-6)

Dermal SensitizationGuinea Pig

Triclosan (99.7% ai)

43206502 Not a Sensitizer NA
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Page 42 of 130

Non-Acute Toxicity

The toxicology database for the triclosan registration review case is comprised principally of 

studies that were available to the agency when the RED was written in 2008. Additional 

published research on triclosan completed after 2008 is also included in the table below. These 

data were included as part of the background materials for the 2011 SAP meeting. The 

toxicology database for triclosan is large. The non-acute toxicology studies comprising the 

database are summarized in tabular format in this scoping document. Full summaries of these 

studies can be found in the Toxicology Disciplinary Chapter in support of the RED in 

regulations.gov in docket number EPA-HQ-OPP-2007-0513-0036.

Table 14 - Non-Acute Toxicity Studies for Triclosan

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.3100 (§82-1)

90-day Oral – Rat

Triclosan Purity: Not 

Reported

133545

Acceptable/Guideline

0, 1000, 3000, and 6000 ppm

NOAEL: 1000 ppm 

The test compound caused nonspecific 

dose-related liver toxicity at 3000 and 6000 

ppm 

870.3100 (§82-1)

90-day Oral – Rat

Triclosan Purity: 99.7%

43022605

Acceptable/Guideline

0, 25, 75, 200, 350, 750, and 

900 mg/kg/day

LOAEL = 25 mg/kg/day based on the 

changes in clinical chemistry and 

hematology parameters as well as lesions in 

the liver.

NOAEL = Not Determined

870.3100 (§82-1)

28-day Oral - Mouse

Triclosan Purity: >99%

44389707

Acceptable - Guideline

0, 6.48, and 135.59 mg/kg/day 

(M), 0, 8.25, and 168.78 

mg/kg/day (F)

LOAEL (M): 135.59 mg/kg/day 

LOAEL (F): 168.78 mg/kg/day based on 

biochemical and morphological effects on 

the liver.

NOAEL(M): 6.48 mg/kg/day

NOAEL (F): 8.25 mg/kg/day

870.3150 (§82-1)

Oral Subchronic (nonrodent) Triclosan Purity: 

Not Reported

96102

Acceptable-Guideline

0, 12.5, 25, 50, and 100 

mg/kg/day

NOAEL: 12.5 mg/kg/day

LOAEL: 25 mg/kg/day based on 

histopathologic changes in the liver of 

treated dogs

870.3250 (§82-2)

90-day Dermal - Rat

Triclosan Purity: 99.7%

43328001

Acceptable/Guideline

0, 10, 40, or 80 mg/kg/day

NOAEL: 40 mg/kg/day (excluding dermal 

findings)

LOAEL: 80 mg/kg/day

Non-guideline

14-day Repeated Dose 

Dermal Toxicity –

Mouse

Triclosan Purity: 99.3%

44389708

Acceptable - Non-Guideline 

0, 0.3, 0.6, 1.5, 3.0, or 6.0 

mg/animal/day

LOAEL: 1.5 mg/animal/day based on 

treatment-related dermal irritation at the 

treatment site and on increased liver weights 

in this treatment group.

NOAEL: 0.6 mg/animal/day

Non-guideline

14-day Repeated Dose 

Dermal Toxicity – Rat

Triclosan Purity: 99.3%

44389710

Acceptable - Non-Guideline

0, 0.3, 0.6, 1.5, 3.0, or 6.0 

mg/animal/day

LOAEL: 6.0 mg/animal/day based on 

treatment-related dermal irritation at the 

treatment site

NOAEL: 3.0 mg/animal/day
Docket Number: EPA-HQ-OPP-2012-0811

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Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.3700a (§83-3)

Developmental – Rat 

(oral)

Triclosan Purity: 99.8%

43817502, 43717503

Acceptable - Guideline

30, 100, or 300 mg/kg/day

Maternal:

LOAEL: 300 mg/kg/day

NOAEL: 100 mg/kg/day

At 300 mg/kg/day, transient diarrhea, 

retarded body weight gain during the period 

of treatment, and reduced food consumption 

and increased water consumption from the 

onset of treatment, throughout the gestation 

period. 

Developmental:

LOAEL: Not Determined (> 300 

mg/kg/day) 

NOAEL: >300 mg/kg/day

No evidence of pre- or postnatal 

developmental toxicity 

870.3700a (§83-3) 

Developmental - Rabbit 

(oral) Triclosan Purity: 

99.8%

43820401, 43022607

Acceptable/- Guideline

15, 50, or 150 mg/kg/day

Maternal: 

LOAEL: 150 mg/kg/day 

NOAEL: 50 mg/kg/day

Developmental:

LOAEL: Not Determined (>150 mg/kg/day)

NOAEL: ≥ 150 mg/kg/day 

870.3800 (§83-3) 

Reproduction - Rat 

(oral) Triclosan Purity: 

≥99%

40623701

Acceptable

0, 300, 1000, and 3000 ppm

(0, 15, 50, and 150 mg/kg/day)

Reproductive:

NOAEL: 50 mg/kg/day

LOAEL: 150 mg/kg/day for decreased 

viability

Systemic /Parental:

NOAEL: 50 mg/kg/day

LOAEL: 150 mg/kg/day for a decrease in 

body weights and food consumption at 

various points during premating, gestation,

and lactation for both F0 and F1 parents

Developmental:

NOAEL: 50 mg/kg/day

LOAEL: 150 mg/kg/day for decreased body 

weight and increased mortality

870.4300 (§83-3)

Chronic Toxicity -

Baboon (oral)

Triclosan Purity: Not 

Reported

133230

Acceptable/Guideline

30, 100, and 300 mg/kg/day

NOAEL: 30 mg/kg/day

LOAEL: 100 mg/kg/day based on clinical 

signs of toxicity.
Docket Number: EPA-HQ-OPP-2012-0811

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Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.4300 (§83-3) 

Chronic/Carcinogenicity 

– Rat

Triclosan Purity: 99% 

42027906

Minimum

2-year study: 0, 300, 1000, or 

3000 ppm (0, 15.3, 52.4, and 

168.0 mg/kg/day in males; 0, 

20.0, 66.9, and 217.4 

mg/kg/day in females)

52 week study: 6000 ppm.

Systemic Toxicity:

NOAEL: 52.4 mg/kg/day based on the 

increase in non-neoplastic liver pathology 

observed in male rats at the 168.0 

mg/kg/day dose.

LOAEL: 168.0 mg/kg/day based on the 

histopathological incidence of hepatic 

necrosis

No evidence of carcinogenicity in this study

870.4200 (§83-3) 

CarcinogenicityMouse

Triclosan Purity: 99%

See, Norman A. (1996)

FDA Review

0, 10, 30, 100, or 200 

mg/kg/day

NOAEL: 10 mg/kg/day in regard to 

tumorigenicity (and all other effects with 

the exception of reduced plasma 

cholesterol)

Increased incidence of liver neoplasms at 30 

mg/kg/day and above.

870.4300 (§83-3) 

Chronic/Carcinogenicity 

– Hamster

Triclosan Purity: 99.5%

44874001, 44751101

Acceptable/Guideline

0, 12.5, 75, and 250 mg/kg/day

NOAEL: 75 mg/kg/day 

LOAEL: 250 mg/kg/day based on 

increased mortality (males), nephropathy, 

histopathologic findings in the stomach and 

testes and general clinical condition 

deterioration - lethargy, hunched posture, 

pallor, thin appearance, unsteady gait

No evidence of carcinogenicity in this study

870.5100 (§84-2)

Bacterial Reverse 

Mutation Test

Triclosan Purity: ≥99%

43533301

Acceptable/Guideline 

0.015, 0.050, 0.15, 0.5, or 1.5 

ug/plate

Negative

Triclosan was cytotoxic at 1.5 ug/plate 

without S9 and at doses of ≥ 0.5 ug/plate 

with S9. No mutagenic response was seen 

at any dose levels with or without S9. 
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Page 45 of 130

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.5100 (§84-2)/

Bacterial Reverse 

Mutation Test/

Triclosan Purity: 

100.5%

44389705

Acceptable/Guideline

TA100 and TA1538 were 

exposed to 0.005-5,000 ug/plate 

(-S9) and 0.005-50 ug/plate 

(±S9). Strains TA98, TA100, 

TA1535, TA1537, and 

TA2538, were evaluated for 

mutagenicity at 0.05 - 5.0 

ug/plate (+S9) and all except 

TA100 at 0.00167-0.167 

ug/plate (-S9). Without S9, 

TA100 was evaluated for 

mutagenicity at 0.00167-0.167 

ug/plate. 

Negative

There were no reproducible, dose-related 

differences in the number of revertant 

colonies in any tester strain at any dose 

level/condition compared to the vehicle 

controls. 

870.5300 (§84-2)/

In Vitro Mammalian 

Cell Gene Mutation 

Test/

Triclosan Purity: > 99%

44389704

Acceptable/Guideline

1 to 25 ug/ml (-S9) and from 1 

to 20 ug/mL (+S9)

Negative

Triclosan was negative for inducing forward 

mutations at the TK locus in mouse L5178Y 

cells both with and without metabolic 

activation. 

870.5375 (§84-2)/

In Vitro Mammalian 

Chromosome Aberration 

Test/

Triclosan Purity: > 99%

47276601

Acceptable/Guideline

0 (DMSO), 0.1, 0.3, 0.5, and 

1.0 ug/ml (+S9) and 0, 4.8, 9.5, 

19, 30, and 38 ug/ml (-S9)

Negative

There was no treatment-related increase in 

clastogenicity at any dose. 

870.5375 (§84-2)/

In Vitro Mammalian 

Chromosome Aberration 

Test/

Triclosan Purity: 99% -

100%

43740801

Acceptable/Guideline

Nonactivated doses of 1 ug/mL 

(7-hour cell harvest), 0.1-3 

ug/ml (18-hour harvest), or 3 

ug/ml (28-hour harvest) and S9-

activated concentrations of 3 

ug/ml (7- and 28-hour cell 

harvests) or 0.1-3 ug/ml (18-

hour harvest). 

Positive

Nonactivated FAT 80’023/Q at 1 and 3 

ug/mL (18-hour harvest) induced a doserelated increase in the yield of cells with 

abnormal chromosome morphology. The 

response was significant (p ≤ 0.001) at the 

higher concentration. A significant increase 

(p ≤ 0.001 was also seen at 3 ug/ml (28-

hour harvest). The most frequently observed 

type of chromosome damage was exchange 

figures. In the presence of S9 activation, 

nonsignificant but concentration dependent 

increases in cells bearing exchange figures 

were also seen at 1 and 3 ug/ml (18-hour 

harvest). The data are, therefore, sufficient 

to conclude that FAT 80’023/Q is active in 

this test system.
Docket Number: EPA-HQ-OPP-2012-0811

Page 46 of 130

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.5385/

Mammalian Bone 

Marrow Chromosomal

Aberration Test/ 

Triclosan Purity: 99% -

100%

43740802

Acceptable/Guideline

4000 mg/kg

Negative 

No signs of overt toxicity or cytotoxicity 

effects on the target organ were seen in any 

treatment group. There was also no 

indication of a clastogenic effect at any 

sacrifice time.

870.5550/

Unscheduled DNA 

Synthesis in Mammalian 

Cells in Culture/

Triclosan Purity: 

100.5% ai

47276602

Acceptable/Guideline

0.25, 0.5, 1.0, and 2.5 μg/mL

Negative

There was no UDS in cultured rat 

hepatocytes at the concentrations tested. 

The positive controls functioned as 

expected.

870.7485/

General Metabolism 

Hamster/

Triclosan Purity: 99% ai

45307501, 45307502

Acceptable/Guideline

2 or 200 mg/kg

After single or repeated oral doses of 2.0 or 

200 mg/kg 14C-triclosan, urine was the 

major route of elimination for triclosan 

radioactivity (60-80% of the administered 

radioactivity). Fecal elimination 

represented from 12-35% of administered 

radioactivity across the oral dose groups. 

Compared to the low dose, administration 

of a single high or repeated dose resulted in 

a shift toward urinary elimination and a 

decrease in fecal elimination.

Peak plasma and blood concentrations of 

triclosan-derived radioactivity occurred at 

one hour post-dose for both the low and

high oral doses. Concentration in plasma 

appeared higher than in whole blood at each 

sampling time. There did not appear to be 

any significant sex differences in blood or 

plasma kinetics at the low or high dose. 

The major urinary metabolite detected after 

oral administration was the glucuronide 

conjugate of triclosan. The major fecal 

metabolite was parent triclosan in all oral 

dose groups (1-8). After intravenous 

administration, triclosan glucuronide was 

also detected as the major urinary 

metabolite. Tissue metabolite analysis 

showed that the glucuronide and sulfate 

conjugates of triclosan were the major 

metabolites detected at the low and high 

oral single doses. 
Docket Number: EPA-HQ-OPP-2012-0811

Page 47 of 130

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.7485/

General Metabolism 

Mouse/

Triclosan Purity: 99% ai

45307503

Acceptable/Guideline

2 or 200 mg/kg

The test material was rapidly absorbed 

following oral administration, and was 

eliminated primarily through the feces, via 

biliary excretion. Urinary excretion was 

secondary to that in the gastrointestinal 

tract. This excretory pattern was consistent 

following I.V. administration as well. 

Primary excreted compounds in the urine 

following single oral exposures included the 

unmetabolized parent compound and two 

parent conjugates (parent sulfate and parent 

glucuronide); fecal excretion was primarily 

that of the free parent compound, as small 

amounts of glucuronide were detected, and 

no sulfate was detected

870.7485/

Metabolism/Kinetics

Multiple species/

Triclosan purity: 99.5%

149464

Acceptable

Intravenous, intraduodenal, or 

gavage at 10 mg/kg (mice), 0.4 

mg/kg (rats), 5 mg/kg (rats, 

rabbits, dogs), or 50 mg/kg 

(rabbits). 

Absorption in rats calculated between 70-

80%. Data not generated for other species 

for absorption. Peak blood levels occurred 

within 30 minutes in rats following a single 

oral or intravenous dose of 5 mg/kg and at 

2-4 hours for dogs. Based upon data from 

rats, tissue burdens declined appreciably 

over 24 hours with no indication of 

accumulation/sequestration. 

Urinary excretion accounted for 3-17% of 

the administered oral dose in rats over a 

168-hour period, and 8.3-8.8% in dogs over 

a 120-hour period. Urinary elimination in 

dogs was somewhat greater following 

intravenous administration; 12.9-17.7% 

over 120 hours. For rabbits, urinary 

excretion was a significant route of 

elimination and accounted for 74.1% of a 

single 50 mg/kg oral dose and 60.4% of a 

single 5 mg/kg oral dose over a 72-hour 

period. The biliary secretion data in rats 

showed that most of the fecal radioactivity 

could be attributed to biliary elimination 

products rather than unabsorbed test 

material. Metabolite data in rats revealed 

glucuronide conjugates and unchanged 

parent compound as biliary metabolites.
Docket Number: EPA-HQ-OPP-2012-0811

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Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.7485/

Metabolism/Kinetics

Rats, Dogs, Baboons, 

Mice/

68161

Unacceptable

14C-triclosan (>98% 

radiochemical purity, lot/batch 

no. not specified) was 

administered to male rats by 

gavage at doses of 5 or 30 

mg/kg (single or 14-day 

repeated). In addition, two 

male beagle dogs and two male 

baboons received single 5 

mg/kg doses in gelatin capsules 

and 10 male mice were given a 

single 10 mg/kg intravenous 

dose.

Peak concentrations in rats were attained 

within three hours after a single oral dose of 

5 mg/kg and the concentrations declined 

approximately five-fold within 24 hours. 

For dogs, somewhat greater blood tmax

values were observed but were variable (2-

8 hours) for the two dogs tested. Timecourse analysis of tissues from mice given a 

single intravenous dose (10 mg/kg) of 14Ctriclosan showed that the highest 

concentrations of radioactivity were initially 

associated with highly perfused 

organs/tissues. These levels significantly 

declined within 30 minutes but the decline 

was somewhat less rapid for organs /tissues 

associated with metabolism and elimination 

and notably increased for the gall bladder.

For monkeys, urinary excretion accounted 

for 56.69% of the administered dose and 

fecal elimination accounted for 25.15%. 

For dogs, urinary and fecal elimination 

accounted for 12.16% and 68.30%, 

respectively, of the administered dose. In 

both species, most of the urinary and fecal 

excretion occurred within 48 hours.
Docket Number: EPA-HQ-OPP-2012-0811

Page 49 of 130

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.7485/

Metabolism/Kinetics

Rats/

47261405

Acceptable

14C-labeled triclosan (99% ai, 

Batch # B-71.32A) was 

administered to two groups of 

10 Wistar rats/dose and four 

groups of 36 Wistar rats/dose.

Groups 1 and 2 were 

administered a single dose of 

2.3 mg/kg or 211 mg/kg of 

radiolabeled triclosan, 

respectively, by gavage and 

sacrificed at 96 hours. Groups 3 

and 4 were administered a 

single dose of 2.2 mg/kg or 199 

mg/kg of radiolabeled triclosan, 

respectively, by gavage and 

groups of 4 rats were sacrificed 

at 0.5, 1, 2, 4, 8, 24, 48, 72, or 

96 hours. Groups 5 and 6 were 

administered thirteen doses of 

2.0 mg/kg or 201 mg/kg of nonradiolabeled triclosan, 

respectively, through food 

followed by a single gavage 

dose of radiolabeled triclosan. 

Fecal excretion predominated at both dose 

levels and dosing regimes. Urine accounted 

for 10-11% of the administered dose, and 

feces 70-80% of the administered dose. Half 

lives for triclosan and its equivalents in the 

plasma ranged from 10.0-12.6 hours, single 

(12.6 or 10 hours, low- or high-dose, 

respectively) and repeated (11.7 or 10.7 

hours, low- or high-dose, respectively) dose 

groups were comparable. 

Repeated doses of triclosan did not cause 

significant changes to the pharmacokinetics 

of triclosan and/or its metabolites in the rat, 

as compared to single dose administration. 

In addition, the results indicate that triclosan 

exhibits saturation of absorption and a 

higher conjugating/metabolizing capacity at 

approximately 200 mg/kg, as compared to 

approximately 2 mg/kg. 

870.7485/

Metabolite Identification

Dogs/Baboons/

79590

Acceptable/non-guideline

Two baboons and two dogs 

were administered a single oral 

dose (5 mg/kg) of [14C]-GP 41 

353 (radiochemical purity 99%; 

chemical purity 99.5%; 

batch/lot nos. not provided)

In the dog, glucuronide conjugates 

accounted for 7% of blood radioactivity and 

sulfate conjugates accounted for 88% of 

radioactivity sampled at three hours. At six 

hours, ~86% of radioactivity in the blood 

was associated with glucuronide/sulfate 

conjugates. For the baboon, glucuronide 

conjugates represented about 25% and 

sulfate conjugates represented about 33% of 

radioactivity at 8 hours postdosing. Similar 

analysis with blood collected at 12 hours 

postdosing revealed somewhat greater 

amounts of sulfate conjugates (~88%). For 

the baboon, analysis of 0-72 hour urine 

samples revealed that approximately 6% of 

the urinary radioactivity was due to 

unchanged triclosan. Up to 75% of the 

urinary radioactivity underwent 

spontaneous hydrolysis presumably due to 

endogenous urinary β-glucuronidase. 
Docket Number: EPA-HQ-OPP-2012-0811

Page 50 of 130

Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

870.7600/

Dermal Absorption

Rabbit/

Triclosan Concentration: 

3%

34335

Acceptable/Guideline

48% of the applied dermal dose was 

absorbed

Liver Biochemical 

Induction –Mouse (oral)

Triclosan Purity: Not 

Reported

44389702

Acceptable/non-guideline

0, 25, 75, 350, and 900 mg/kg 

bw for M and 0, 25, 350, and 

900 mg/kg bw for F

The test article is a strong, but reversible 

barbiturate-type and peroxisome 

proliferator-type inducer of foreign 

compound metabolizing enzymes in male 

and female mice

Liver Biochemical 

Induction –Rat/

Triclosan Purity: Not 

Reported

44389703

Acceptable/non-guideline

0, 300, 1500, and 6000 ppm

Food consumption was reduced in all test 

groups with the exception of the 6000 ppm 

dose group which had a reduced food intake 

on day 1 and then an almost 3-fold increase 

over the control group. Group mean body 

weight was not significantly changed except 

in the 6000 ppm group which was slightly 

decreased (4-8%) over the first 8 days of the 

study. At the end of the study, rats receiving 

6000 ppm showed a significant increased 

absolute and relative liver weight.

Significant effects were observed for 

several biochemical parameters in the liver 

at the 6000 ppm dose level. Cytochrome P450 content was approximately doubled in 

the high dose group, while activity of 

glutathione-S-transferase was increased by 

65%. Other enzymes affected at the 6000 

ppm dose level included an increase in 

lauric acid hydroxylation and an increase in 

PROD and EROD activity. In general, those 

animals allowed to recover for 28 days 

following the 14-day administration of test 

chemical showed no significant induction or 

inhibition of enzyme activities.

Liver Biochemical 

Induction –Hamster/

Triclosan Purity: 99.5% 

44389706

Acceptable/Non-Guideline 

0, 700, 5,000, and 15,000 ppm 

[approximately 0, 49.9, 309.8, 

799.0 mg/kg/day (M) and 46, 

314.3, and 958.8 mg/kg/day 

(F)] or 0 or 15000 ppm 

(recovery groups) 

Systemic Toxicity

NOEL: 700 ppm 

LOEL: 5000 ppm based on induction of 

total cytochrome P-450, EROD, and PROD 

in male and female hamsters, and induction 

of Mab clo4 immunoreactive protein 

(CYP4A peroxisome proliferators inducible 

P-450) in male hamsters.
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Guideline Number/

Study Type/

Test Substance (% ai)

MRID Number (Year)/

Citation/

Classification/ Doses

Results

Liver Cell Proliferation 

–Mouse/

Triclosan Purity: Not 

Reported

44389701

Acceptable/Guideline

0, 25, 75, 200, 350, or 900 

mg/kg/day

NOAEL(M): 25 mg/kg/day

NOAEL(F): 75 mg/kg/day

Liver Cell Proliferation 

–Mouse/

Triclosan Purity: Not 

Reported

Eldridge, 1995 

44389701

Acceptable/Guideline

0, 25, 75, 200, 350, 750, or 900 

mg/kg/day

An increase in the labeling index was 

apparent at 200 mg/kg/day and above for 

male and female mice. The labeling index 

was increased at day 45 in both sexes at 350 

and 900 mg/kg/day, and as noted, this 

continued at these dose levels at 90 days as 

well as the increase observed at 200 

mg/kg/day at 90 days for both sexes. The 

observation of an increase in labeling index 

from this study, in conjunction with other 

data which show toxicity to the liver of rats 

and mice, indicate cytolethality of triclosan 

which is followed by induced cellular 

regeneration. However, there may be 

species differences in the response to 

triclosan hepatotoxicity.

In the report, it was noted that the mode by 

which a chemical induces cell proliferation 

is an important consideration. In the case of 

triclosan, the evidence suggests a 

hepatotoxic effect followed by regenerative 

cell turnover, in contrast to agents which act 

as direct mitogens. For chemicals producing 

increased cell turnover through 

cytolethality, a threshold can be inferred 

below which these effects would not occur. 

This scenario could apply to triclosan based 

on the available data.

Other Toxicological Effects

In addition to the effects of triclosan related to cellular proliferation (summarized in the table 

above), triclosan has also been shown to have effects on the mammalian endocrine system. The 

studies conducted on these effects are summarized below. 

Anti-estrogenic/Androgenic Effects

Gee et al. (2007) reported displacement of 3H-estradiol from the estrogen receptor of human 

MCF7 breast cancer cells by triclosan and inhibition of the estrogen-responsive ERE-CAT 

reporter gene by triclosan at 10-5 M in the presence of 10-10 M estradiol. Triclosan was also 
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shown to have anti-androgenic activity in this study as shown by displacement of 3H-testosterone 

from the rat androgen receptor, although a 1000-fold molar excess of triclosan was needed to 

produce a 49% displacement of testosterone. Using a mouse mammary tumor cell line with a 

stably-transfected androgen reporter gene (LTR-CAT), induction of CAT activity by testosterone 

was inhibited in the presence of triclosan at 10-5 M and above. The proliferative response of these 

mouse mammary tumor cells to testosterone was also inhibited by triclosan. 

Ahn et al. (2008) examined the biological activity of triclosan in in vitro, cell-based, and nuclear 

receptor-responsive bioassays for the aryl hydrocarbon (Ah), estrogen (E), and androgen (A) 

receptors. As reported in the study, triclosan at a concentration of 10 μM induced luciferase 

expression to 40% of that seen with 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD), but it 

inhibited the induction of luciferase expression by TCDD by approximately 30%. These 

agonist/antagonist results are consistent with TCS being a partial agonist of the Ah receptor. In 

both the ER- and AR-responsive bioassays, triclosan exhibited antagonistic activity in this study. 

Chen et al. (2007) examined the anti-androgenic potential of triclosan using a cell-based stably 

transfected cell line lacking critical steroid metabolizing enzymes. Triclosan alone exhibited no 

androgenic activity at concentrations up to 10 μM, but transcriptional activity in the presence of 

0.125 nM testosterone was inhibited by 10 μM triclosan by 92%, and by 38.8% at 1.0 μM 

triclosan. 

Estrogenic Effects

Tamura et al. (2006) studied the androgen receptor (AR) activity of listed chemicals, so called 

SPEED 98, by the Ministry of the Environment, Japan, and structurally related chemicals was 

characterized using MDA-kb2 human breast cancer cells stably expressing an androgen 

responsive luciferase reporter gene, MMTV-luc. Based on results generated above suggesting 

that chemicals with diverse structures were capable of disrupting the endocrine systems mediated 

by AR, a comparative molecular field analysis (C0MFA) model was developed to analyze the 

structural requirements necessary to disrupt AR function. Triclosan had AR antagonist activity 

with an IC50 value of 7.5 μM, which was as potent as linuron based on in vitro MDA-kb2 

reporter gene assay. 

Stoker et al. (2010) examined the potential estrogenic effects of triclosan using the rat weanling 

uterotrophic assay, an assay for detection of uterine growth in response to estrogen agonists. No 

changes in mean wet or blotted uterine weight were observed following dosing with triclosan 

alone for three days (1.18 to 300 mg/kg triclosan). However, there was a significant dosedependent increase in the mean uterine wet and blotted weight in the cotreated groups who

received 4.69 to 37.5 mg/kg triclosan plus 3 ug/kg ethinyl estradiol for three days. The data from 

the uterotrophic assay showed that triclosan enhanced the uterine response to ethinyl estradiol. 

Triclosan appeared to stimulate this estrogen dependent response by enhancing the activity of 

exogenously administered estrogen and not by a direct stimulation of the estrogen receptor, as 
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triclosan doses as high as 300 mg/kg without cotreatment with EE did not alter uterine weight or 

histology. 

Effects on Thyroid 

Recent in vivo data from rats provides evidence that triclosan alters thyroid hormone 

homeostasis. Crofton et al (2007) demonstrated that short-term (4-day) oral exposure to 

triclosan decreased serum total T4 concentrations and increased liver weights. Using a 

benchmark response of 20%, the benchmark dose (BMD) and lower bound (BMDL) for T4 were 

69.7 and 35.6 mg/kg/day, respectively. This study discussed the possibility of more than one 

mechanism involved in the decrease of T4 levels after oral exposure to triclosan, including 

activation of the human pregnane X receptor (PXR; Jacobs et al., 2005) resulting in increases in 

sulfonation or glucuronidation activity.

The effect of triclosan on thyroid has also been investigated using the pubertal assay (US EPA, 

2008). Weanling male rats were dosed by oral gavage for 30 days starting on postnatal day 23 

with 0, 3, 30, 100, 200 or 300 mg/kg/day of triclosan. Triclosan did not alter pubertal 

development, reproductive tract development or gonadal histopathology, T4 concentrations 

decreased by 47.4, 49.8, 80, and 81% at 30, 100, 200, and 300 mg/kg respectively. 

Triiodothyronine (T3) was only significantly decreased at 200 mg/kg, while thyroid stimulating 

hormone (TSH) levels were unaffected at any dose level. Thyroid histology was also not altered 

at 100 and 200 mg/kg. Histology at 300 mg/kg is currently under examination. Mean liver 

weight of dosed male rats was increased significantly at the 100 mg/kg dose and above, 

suggestive of hepatic enzyme induction and increased clearance of thyroid hormone. Using a 

BMR of 20% and the BMD was calculated as 14.51 mg/kg with a benchmark dose limit 

(BMDL) of 7.23.

The mechanism of action for the decrease in T4 levels observed in juvenile rats in this study was 

not investigated. Mean liver weight of dosed male rats was increased significantly at the 100 

mg/kg dose and above, suggestive of hepatic enzyme induction and increased clearance of 

thyroid hormone. However, the study noted no induction of liver UDP-glucuronyl transferase at 

the 3 or 30 mg/kg dose levels. In a shorter term study in which weanling female Long-Evans rats 

were exposed by oral gavage for 4 consecutive days to triclosan at 0, 10, 30, 100, 300, or 1000 

mg/kg (Crofton et al., 2007), significant decreases in serum T4 concentrations were observed at 

100 mg/kg and above in a dose-related manner. This study discussed the possibility of more than 

one mechanism involved in the decrease of T4 levels after oral exposure to triclosan, including 

activation of the human pregnane X receptor (PXR; Jacobs et al., 2005) resulting in increases in 

sulfonation or glucuronidation activity. Further research is needed in this area. 

While there are some uncertainties with respect to the pharmacodynamics of triclosan, the 

pharmacokinetics of triclosan, which has been studied in several animal species and in humans, 

shows similar half-life of elimination in experimental animal species studied (rat, hamster, 
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mouse) in comparison to humans. It has been observed, however, that enterohepatic circulation 

of triclosan occurs in the rat, and that a significant first-pass effect occurs in humans. 

Comparison of comparable oral doses administered to rats and humans shows smaller area under 

the curve (AUC) values for humans compared to rats, suggesting less overall systemic exposure. 

In addition, it is also known that the rat is a more sensitive species than the human with respect 

to perturbations in thyroid homeostasis, based on the shorter half-life of T4 in the rat (12-24 

hours) compared to humans (5-9 days), and the lack of the high affinity binding protein 

thyroxine binding globulin in rats (Capen, 1996). 
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REFERENCES TOXICOLOGY DATA

MRID 34335: Stierlin, H. (1968) “Percutaneous Absorption of GP 41 353 in the Rat and the 

Rabbit.” (Unpublished study; prepared by J.R. Geigy, AG, submitted by Ciba-Geigy Corp., 

Greens- boro, N.C.; CDL:000506-M) 

MRID 43429: Stenger, E.G.; Scharer, (1963) “Local Effects on Rabbit's Eye.” (Unpublished 

study; prepared by J.R. Geigy, AG, Switzerland, submitted by Ciba-Geigy Corp., Greensboro, 

N.C.; CDL:108210-J) 

MRID 96102: Burther, B.R.; Gordon, D.E. (1973) “Report to Ciba-Geigy Corporation: 90-day 

Subacute Oral Toxicity Study with Irgasan DP-300 in Beagle Dogs: IBT No. C1435.” 

(Unpublished study; prepared by Industrial Bio-Test Laboratories, Inc., submitted by Ciba-Geigy 

Corp., Greensboro, N.C.; CDL:008400-C) 

MRID 100178/130187: Schoenig, G. (1967) “Report to Geigy Chemical Company: Acute 

Dermal Toxicity Study on CH 3565: IBT No. A5460.” (Unpublished study; prepared by 

Industrial Bio-Test Laboratories, Inc., submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:000503-D) 

MRID 133545: Goldsmith, L. (1983) 90-Day Oral Toxicity Study in Rats with Fat 80’023/H: 

LBI Project No. 22188. Final Report. (Unpublished study received Dec. 23, 1983 under 100-

502; submitted by Ciba-Geigy Corp.)

MRID 251773: Drake, J.C. & Buxtorf, A. (1976) 1 Year Oral Toxicity Study in Baboons with 

Compound FAT 80 023/A. Geigy Pharmaceuticals, Toxicology Department. 

MRID 40623701: Morseth, S.L. (1988) “Two-Generation Reproduction Study in Rats with FAT 

80’02390” Hazleton Laboratories America, Inc. 

MRID 42027906: Study 1 - Yau, E.T. and Green, J.D. (1986) Fat 80’023 2 Year Oral 

Administration to Rats; Study 2 – Parkes, D.G. (1986) Determination of Fat 80’023 in Blood and 

Tissue Samples Taken During a Two-Year Chronic Oral Toxicity/Oncogenicity Study in Albino 

Rats (24-month Final Report). Ciba-Geigy Corporation. 

MRID 42306902, 43310501: Duchosal F. and Ph. Thevenaz (1990) “4-Hour Acute Inhalation

Toxicity Study with FAT 80’023/Q in Rats” Ciba-Geigy Ltd. 

MRID 42306903: Sachsse, K.; Ullman, L. (1975) Skin Irritation in the Rabbits after Single 

Application of FAT 80’023/A. Unpublished Study Conducted by Ciba Geigy Ltd., Basel 
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Page 56 of 130

Switzerland. Project No. Siss 4719. Submitted to EPA by Chemical Division of Ciba Geigy 

Corp. (9/11/75).

MRID 43022605: Trutter, Janet A. (1993) “13-Week Subchronic Oral Toxicity Study of 

Triclosan in CD-1® Mice.” Hazleton Washington, Inc. 

MRID 43206501: Wnorowski, Gary. (1994) “Acute Toxicity Limit Test for Triclosan 

(Irgasan® DP 300) Product Safety Labs.

MRID 43206502: Wnorowski, G. (1994) Dermal Sensitization Test-Buehler Method for 

Triclosan (Irgasan® DP 300) Lot No. 5.2.0211.0. Product Safety Labs; Study No. 2635. 

Submitted to EPA by Ciba-Geigy Corp. Unpublished.

MRID 43328001: Trimmer, Gary W. (1994) “90-Day Subchronic Dermal Toxicity Study in the 

Rat with Satellite Group with Irgasan DP300 (MRD-92-399)” Exxon Biomedical Sciences, Inc.

MRID 43533301: Jones, E., Wilson, L.A. (1988) “Ames Metabolic Activation Test to Address 

the Potential Mutagenic Effect of Triclosan (Irgasan DP 300)” Huntingdon Research Center, Ltd. 

Cambridgeshire, England. 

MRID 43740801: Heidemann, A. (1990) “Chromosome Aberration Assay in Chinese Hamster 

V79 Cells In Vitro with FAT 80’023/Q (Irgasan® DP 300); Cytotest Cell Research GMBH & 

Co. KG, Federal Republic of Germany; Study No. 179100. Unpublished. 

MRID 43740802: Volkner, W. (1991) “Chromosome Aberration Assay in Bone Marrow Cells of 

the Rat with FAT 80’023/Q (Irgasan® DP300); Cytotest Cell Research GMBH & Co. KG, 

Federal Republic of Germany; Study No. 218305. Unpublished. 

MRID 43817502, 43817503: Denning, H.J., Sliwa, S., and Willson, G.A. (1992) “Triclosan: 

Effects on Pregnancy and Post-Natal Development in Rats: Volume 1, Volume 2 and 

Appendices 1-17” Unilever Research, Colworth/ Welwyn Lab.

MRID 43820401, 43022607: Schroeder, R.E. et al. (1992) “A Segment II Teratology Study in 

Rabbits with Irgacare MP” Bio/dynamics Inc. 

MRID 44389701: Eldrige, S. (1993) Cell Proliferation in Rodent Liver: (Triclosan): Final 

Report: Lab Project Number: 142. Unpublished study prepared by Pathology Associates, Inc. 14 

p.

MRID 44389702: Molitor, E., Persohn, E., Thomas, H. “The Effect of FAT 80’023/Q (Irgasan 

DP 300) on Selected Biochemical Liver Parameters Following Subchronic Dietary 

Administration to Male and Female Mice. Ciba-Geigy Limited, Switzerland, Report CB 91/18, 

May 22, 1992. 
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MRID 44389703: Molitor, E.; Persohn, E. (1993) The Effects of FAT 80’023/Q (Irgasan DP 

300) on Selected Biochemical and Morphological Liver Parameters Following Dietary 

Administration to Male Rats: Lab Project Number: CB 92/28. Unpublished study prepared by 

Ciba-Geigy Ltd. 70p.

MRID 44389704: Henderson, L.M., et al. (1988) An Assessment of the Mutagenic Potential of 

Triclosan Using the Mouse Lymphoma TK Locus Assay. Huntingdon Research Center Ltd., 

Huntingdon, Cambridgeshire, PE18 6ES, England. Study No. ULR 216/88644. Unpublished.

MRID 44389705: Stankowski, L.F., Jr. et al. (1993) Amended Final Report, Ames/Salmonella 

Plate Incorporation Assay on Test Article 39316 (CC #14663-09). Pharmakon USA, P.O. Box 

609, Waverly, PA. Laboratory Study Report No. PH 301-CP-001-93. Unpublished.

MRID 44389706: Thomas, Rer. Nat. H. (1994) The Effect of FAT 80’023/Q and the Model 

Inducers Phenobarbitone, 3-Methylcholanthrene, Pregnenolone 16 ∞ -carbonitrile and Nafenopin 

on Selected Biochemical and Morphological Liver Parameters in the Syrian Hamster. Study 

conducted by Ciba-Geigy Limited. Study number CB 93/40. Unpublished.

MRID 44389707: Thevenaz, Dr. Phil. (1987) Final Report: FAT 80023: 28-Day Toxicity Study 

in Mice (Administration in Feed) with Special Reference to Histopathology. Ciba-Geigy Ltd., 

Basle, Switzerland. Unpublished.

MRID 44389708: Burns, J.M. (1997) 14-Day Repeated Dose Dermal Study of Triclosan in CD-1 

Mice. Corning Hazleton Incorporated (CHV), 9200 Leesburg Pike, Vienna, Virginia. 

Laboratory Study No. CHV 2763-100. April 29, 1997. Unpublished. 

MRID 44389710: Burns, J.M. (1997) 14-Day Repeated Dose Dermal Study of Triclosan in Rats. 

Corning Hazleton Incorporated (CHV), 9200 Leesburg Pike, Vienna, Virginia. Laboratory 

Study No. CHV 6718-102. Unpublished.

MRID 44874001, 44751101: Chambers, P.R. (1999) “Potential Tumorigenic and Chronic 

Toxicity Effects in Prolonged Dietary Administration to Hamsters.” Huntingdon Life Sciences 

Ltd., Huntingdon, England. CBG 756/972896.

MRID 45307501, 45307502: Van Dijk, Dr. A. (1994) “14C- Triclosan: Absorption, Distribution, 

Metabolism, and Elimination after Single/Repeated Oral and Intravenous Administration to 

Hamsters.” RCC Umweltchemie AG. RCC Project No. 351707. 
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MRID 45307503: Van Dijk, Dr. A. (1995) “14C- Triclosan: Absorption, Distribution, 

Metabolism, and Elimination after Single/Repeated Oral and Intravenous Administration to 

Mice.” RCC Umweltchemie AG. RCC Project No. 337781. 

Tox Record No. 001955, 001956 (1968) 

Tox Record No. 001968 (1977) 

Broker, P.C., Gray, V.M., Howell, A. (1988) “Analysis of Metaphase Chromosomes Obtained 

from CHO Cells Cultured in vitro and Treated with Triclosan.” Huntingdon Research Center, 

Ltd. ULR 214/88731; Unilever Test #: KC880171. Unpublished.

Capen, C. Toxic Responses of the Endocrine System. In: Casarett and Doull’s Toxicology: The 

Basic Science of Poisons, 5th ed., Curtis D. Klaassen, Ph.D., editor. McGraw-Hill. 

Chen, J. et al. (2007): Antiandrogenic properties of parabens and other phenolic containing small 

molecules in personal care products. Toxicol. Appl. Pharnacol. 221: 278-284. 

Crofton, KM; Paul, KB; DeVito, PB; Hedgea, JH. 2007. Short-term in vivo exposure to the 

water contaminant triclosan: Evidence for disruption of thyroxine. Environmental Toxicology 

and Pharmacology 24: 194–197. 

Eldrige, S. (1995) Cell Proliferation in Rodent Liver. Study conducted by Pathology Associates, 

Inc. Submitted to EPA (no MRID). Unpublished.

Gee, R.H., Taylor, C.N., Darbre, P.D. (2008): Oestrogenic and androgenic activity of triclosan in 

breast cancer cells. J. Appl. Toxicol. 28: 78-91. 

San Sebastian, J.R., Morgan, J.M. (1993) “Rat Hepatocyte Primary Culture/DNA Repair Test on 

39317” Pharmakon Research International, Inc. Pharmakon Study #: PH311-CP-001-93. 

Unpublished. 

See, Norman A. (1996) Review and Evaluation of Pharmacology and Toxicology Data Division 

of Dermatologic and Dental Drug Products (HFD-540) Food and Drug Administration.

Stoker, T.E., Gibson, E.K., Zorrilla, L.M. (2010) Triclosan exposure modulates estrogendependent responses in the female Wistar rat. Toxicol. Sci. 177(1):45-53.

Tamura,H., Y. Ishimoto., T. Fujikawa et al. (2006). Use of Structural basis for androgen receptor 

agonists and Antagonists: Interaction of SPEED 98-listed chemicals and Related compounds 
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with the androgen receptor based on an In vitro reporter gene assay and 3D-QSAR. MRID to be 

Assigned. Bioorganic & Medicinal Chemistry. 14:7160-7174. 

U.S. EPA 2008). T. E. Stoker and W. Setzer. The Endocrine Disrupting Effects of Triclosan, a 

common pharmaceutical and personal care product: Alteration of the Thyroid Axis Following a 

Peri-juvenile Exposure in the Male Wistar Rat. EPA/600/X-08/010. 
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APPENDIX B: Environmental Fate

For the registration review of triclosan, the agency will review environmental fate and exposure 

from submitted guideline studies, open literature, and government databases. This final work 

plan is based on the 2008 RED (http://www.epa.gov/oppsrrd1/REDs/2340red.pdf ) and 

additional data from guideline and literature studies that have become available since the 2008 

RED.

Under aqueous conditions because triclosan has a pKa of 8.14 (MRID 42027904), it is expected

to exist in a chemically-neutral (non-electrically-charged) form at pH < 7.5. The neutral or nonionized state is generally the more bioavailable and toxic form. As the pH of soil or water 

becomes higher or more basic, triclosan is more likely to be negatively-charged and therefore 

also more mobile in soil as soil too becomes more negatively charged under higher pH. Based 

on the log Kow value of 4.8, bioconcentration in aquatic organisms is indicated. Oyster and fish 

bioconcentration data were required by the post-RED DCI for triclosan with monitoring of its 

major toxic metabolites such as methyl triclosan.

Open literature studies would indicate that wastewater treatment is likely to remove more than 

80% of triclosan and that under anaerobic conditions concentrations in sludge can be expected to 

increase because the sludge is degrading faster than triclosan. The primary degradation products 

in chlorinated water treatment include 4-chloro triclosan, 6-chloro triclosan, and 4,6-dichloro 

triclosan. These open literature studies will be formally reviewed by the agency during 

registration review. 

A detailed discussion of environmental fate properties of triclosan and its major transformation 

products methyl triclosan (methoxy triclosan), 2,4-dichlorophenol, chlorinated triclosan (4-

chloro-, 6-chloro-, and 4,6-dichloro-), and the predominant dioxins such as 2,7/2,8-

dichlorodioxin based on these sources is provided in this appendix. For exposure modeling, a 

total toxics residue approach will be used in the risk assessment. This means that estimates of 

exposure will include consideration of both parent and its major toxic degradates.

Methyl triclosan (methyoxy triclosan) is formed by microorganisms in the presence of oxygen. 

It has been observed to form at significant (>10 %) of applied triclosan in aerobic soil (nonflooded top layer of soil) and in WWTPs to a lesser extent. 

Chlorophenol compounds (2,4-dichloro, 4,6-dichloro-, 2,6-dichloro-, and 2,4,6-trichloro) are 

formed as a result of photodegradation in water (43022608, acceptable study) and the 

combination of photodegration in water and aquatic metabolism (Buth, 2009). In the Buth (2009 

article), dioxins were formed at approximately 1,000X less than the parent triclosan 

concentration. The Buth (2009) article will be formally reviewed in Registration Review. 
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Chlorinated triclosan (4-chloro-, 6-chloro-, and 4,6-dichloro-) were formed in the Buth (2009) 

study as a result of chlorination of wastewater. The Buth (2009) article will be formally

reviewed in Registration Review.

Dioxins are formed from triclosan that is exposed to sunlight in water. The predominant dioxins 

formed include 2,7- and 2,8-dichlorodioxin, but others with 3 or 4 chlorine atoms have been 

observed and include: 1,2,8- and 2,3,7- trichlorodioxins and 1,2,3,8-tetrachlorodioxin (TCDD) 

in natural waters (Buth, 2009 and Buth, 2010). The Buth (2009 and 2010) articles will be 

formally reviewed in Registration Review. From a preliminary examination of which dioxins are 

formed in these studies, they are not among the congeners of concern for humans or ecological 

receptors (i.e., have no 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) toxicity equivalency 

factors17,18). Appendix F contains a list of the 17 congeners of ecological concern.

To refine estimates of exposure concentrations in surface waters from textile and plastic material 

preservative use sites, monitoring of textile and plastic material preservative use site effluent 

wastewater was also required as part of the post-RED DCI (as noted in Table 7, the special study 

for Surface Water Monitoring). Investigation of the plastic manufacturing process where 

triclosan is used revealed that they are limited to those where the plastic does not come into 

contact with industrial process water. Such a lack of contact means there is no environmental 

exposure pathway for aquatic and terrestrial wildlife. Because there are those plastic 

manufacturing processes where the plastic does come into contact with industrial process water, 

the label has been changed to limit the use of triclosan as a material preservative to plastic 

manufacturing that does not come into contact with process water. Monitoring at two textile 

facilities was recently completed and submitted to the agency for review (MRID 48858101). 

The results of this study showed that average and maximum in-stream wastewater concentrations 

(IWC) for triclosan were 3.2 ng/L and 6.1 ng/L for Facility 1, and 33.1 ng/L and 43.2 ng/L for 

Facility 2, respectively. . Methyltriclosan was below detection (<1.9 ng/L) at both facilities. The 

study was found to be acceptable.

To eliminate unnecessary decimals in values, most concentration units in this document are 

expressed either as nanograms per liter (ng/L) for liquids, nanograms per gram (ng/g) for solids 

(mostly sludge), or picograms per gram (pg/g) for solids (e.g., dioxins in sediments). These units 

translate to parts-per-trillion (ppt) for liquid [1 x 10-10 %], parts-per-trillion (ppb) for sewage 

sludge [1 x 10-7 %], or parts-per-trillion for dioxin in sediments. 

The physical-chemical properties of triclosan reveal that triclosan has relatively low water 

solubility (12 ppm or mg/l), a relatively low vapor pressure (5.2 x 10-6 mm Hg at 25 oC) (MRID 

42027904), but has limited tendency to volatilize from water with a Henry’s Law values of 5 x 

10-9 atm-m3/mol. As a result, it is not expected to volatilize (move from soil or water to air) 

 17 http://www.epa.gov/raf/files/tefs-for-dioxin-epa-00-r-10-005-final.pdf 18 http://www.epa.gov/raf/tefframework/index.htm
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significantly (criteria for non-volatility is vapor pressure <10-6 mm Hg). It is expected to exist in 

a chemically-neutral (non-electrically-charged) form in acidic and neutral pH conditions and a 

charged state under more basic or alkaline conditions because the pKa is 8.14 (MRID 

42027904). At pH values equivalent to the pKa half of the triclosan is neutral and half is in a 

charged state, as the pH drops below the pKa value the neutral state is predominant and as the 

pH increases above the pKa the charged state is predominant (Price et al., 2010). For aquatic 

animals the charged state is usually less toxic than the neutral state of a compound. As the pH of 

the soil increases, both the soil/sediment and triclosan become more negatively-charged and the 

like charges will lead to more association with water in the presence of soil and sediment. 

The agency has received and summarized numerous peer-reviewed literature studies on the 

environmental fate of triclosan following the publication of the RED. Given the wide range of 

values and varying information, the agency anticipates reviewing critical environmental fate data 

before publication of the FWP.

Abiotic Degradation of Triclosan and Transformation Products

The agency has received studies on hydrolysis (835.2120) and photodegradation in water 

(835.2240) that satisfy these data requirements. The studies demonstrate that triclosan is stable 

to abiotic hydrolysis but degrades rapidly in the presence of light. The hydrolysis study (MRID 

42027908) was a preliminary study but it was sufficient to demonstrate the stability of triclosan 

at 50 o

C. In the photodegradation in water study (MRID 43022608), triclosan degraded with a 

half-life of 41 minutes and formed the degradate 2,4-dichlorophenol (2,4-DCP) which reached 

97 % of the applied parent compound and was stable. Photodegradation in water is expected to 

be the primary route of dissipation for triclosan in shallow, well-mixed water with no suspended 

or bottom sediment. However, this route of dissipation in water will be limited in nature by 

water depth and light attenuation, suspended sediment, shading, and sorption to bottom sediment. 

Six aqueous photoloysis studies were found in the literature, and are also cited in Table 15. 

These studies will be reviewed as part of the registration review action because they appear to 

provide additional information on longer half-lives in the environment as well as the presence of 

additional degradation products such as dioxins and dichlorohydroxydiphenyl ether (DCHD). 

From a preliminary examination of which dioxins are formed in these studies, they are not those 

identified as either of concern for human health or ecological receptors (i.e., have no 2,3,7,8-

tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) toxicity equivalency factors19,20). Table 15 also 

includes a predicted half-life for photodegradation in air (835.2370) which is not anticipated to 

be critical for the risk assessment because triclosan will not be present in air based on its vapor 

pressure (5.2 x 10-6 mm Hg) and Henry’s Law constant (5 x 10-9 atm m3 mol-1

). 

 19 http://www.epa.gov/raf/files/tefs-for-dioxin-epa-00-r-10-005-final.pdf 20 http://www.epa.gov/raf/tefframework/index.htm
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Table 15 - Abiotic Degradation of Triclosan and Degradate Formation

Parameter

Half-lives 

(parent triclosan unless 

specified)

Source (Open literature study unless specified)/

Study Classification/

Comments

Hydrolysis 

(OPPTS 835.2120, 161-1)

pH 4

pH 7

pH 9

Stable at 50°C Pointurier, 1990; Guideline study, MRID 42027908/

Supplemental (preliminary study only), but no 

additional data expected to be required/

Langer et al., 1972; MRID 00046300/

Not reviewed because it only addressed theories of 

dioxin formation

Aqueous photolysis 

(OPPTS 835.2240, 161-2)

Guideline study

41 min Spare, 1993; Guideline study, MRID 43022608/

Acceptable/

Degradate: 2,4-dichlorophenol (DCP) increased to 

94-97 % by end of study and did not degrade.

Photolysis in water and 

degradate formation 

(OPPTS 835.2210, 

literature studies)

5 hours in Deionized water 

and Suwanee River water in 

U.S.

Latch et al., 2004; No MRID assigned/

Quality unknown, study not formally reviewed/

Degradate: 2,4-DCP formed at up to 3.1 % of applied 

triclosan

Degradate: 2,8-dichlorobenzo-p-dioxin (2,8-DCDD) 

formed at 4-12 % of applied triclosan (higher amounts 

at higher pHs)

4-6 min (sunlight)

5-8 min (artificial UV light)

in irradiated wastewater 

samples from Spain

Sanchez-Prado et al., 2006; No MRID assigned/

Quality unknown, study not formally reviewed/

Primary degradation products were 2,8-DCDD and 

dichlorohydroxydiphenyl ether (DCHD). 2,8-DCDD 

reached 100 % of applied triclosan by 5-10 minutes 

with half-life of ~20 minutes.

DCHD reached 100 % by 2 minutes with a half-life of 

~25 minutes.

8 days (freshwater)

4 days (saltwater) 

26 days (2,8-DCDD in 

freshwater)

11 days (2,8-DCDD in salt 

water)

Aranami and Readman, 2007; No MRID assigned/

Quality unknown, study not formally reviewed/

Primary degradation product was 2,8-DCDD in freshand salt water. 

2,8-DCDD peaked at 20 days for both fresh- and saltwater (study length of 120 days).

2,8-DCDD reached 60 and 90 % of triclosan in freshand salt-water 

23 hours (deionized water)

18 hours (wastewater) 

Mezcua et al., 2004; No MRID assigned/

Quality unknown, study not formally reviewed/

Photodegradation of triclosan in water and wastewater 

in Spain
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Parameter

Half-lives 

(parent triclosan unless 

specified)

Source (Open literature study unless specified)/

Study Classification/

Comments

Photolysis in water and 

degradate formation 

(OPPTS 835.2210, 

literature studies)

No specific half-lives of 

parent triclosan or 

degradates in the study 

Buth et al., 2009; MRID 49159301/

Quality unknown, study not formally reviewed/

Formation of 1,2,8- and 2,3,7- trichlorodioxins and 

1,2,3,8-tetrachlorodioxins at up to 2.5 % of 4-chloro 

triclosan, 6-chloro triclosan, and 4,6-dichlorotriclosan 

in irradiated buffer solutions and natural waters. 

Indirect photodegradation of dissolved organic matter 

slower than direct photodegradation of chlorinated 

triclosans.

Photoproducts of triclosan

and dioxin conogers in 

sediment cores of 

Mississippi River and 

Lake Pepin in Minnesota 

where water treatment 

plant outlet was located

(No guideline numbers)

Mississippi River

Triclosan increased to 10 

ng/g in 1998 and decreased 

to four (4) ng/g in 2008 (last 

analysis)

2,8-DCDD, 1,2,8-TriCDD, 

2,3,7--Tri-CDD, and 

1,2,3,8-TCDD increased to 

80, 3, 3, and 4 pg/g by 2003, 

respectively. 

Concentrations declined to 

20, 1, 1, and 1 pg/g by 2008 

(last analysis), respectively

Lake Pepin

Triclosan increased to 13-14 

ng/g in 1998-2003 (last 

analysis)

2,8-DCDD, 1,2,8-TriCDD, 

2,3,7--Tri-CDD, and 

1,2,3,8-TCDD increased to 

85, 3, 3, and 4 pg/g by 

2003-2008, 1990, 1990-

2008, and 2008, 

respectively. 

2,8-DCDD concentrations 

declined to 70 pg/g by 2008 

(last sample), respectively.

Buth et al., 2010; MRID 49159302/

Quality unknown, study not formally reviewed/

Cores taken in 2008

Dioxin congeners present in sediment at about 1,000 

times lower than triclosan (pg/g versus ng/g (partsper-trillion versus parts-per billion))

Dioxins in sediment reached 31 % by mass in later 

depositions

2,8-DCDD was primary dioxin present in samples 

(>90 %).

Photolysis in Air 

(OPPTS 835.2370, 161-4)

8 hours (seasonal mean) EPI-Web 4.1 Program (AOP Program (v1.92) Results 

for reaction with hydroxyl radicals

Laboratory Metabolism Properties of Triclosan

The agency requires laboratory metabolism studies to provide a measure of the biotic 

degradation potential of a compound in the environment, without the bias from dissipation by 

leaching or runoff. The agency has received acceptable guideline studies on laboratory aerobic 

soil metabolism (835.4100) and aerobic aquatic metabolism (835.4300). The anaerobic soil 
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metabolism (835.4200) data requirement is satisfied with two supplemental open literature 

studies and the anaerobic aquatic metabolism (835.4400) data requirement has been waived.

The agency has also received supplemental guideline studies for soil nitrification (OECD 216) 

and soil respiration (OECD 217) for triclosan that satisfy these data requirements. Table 16

contains the results and additional details for all laboratory metabolism studies for triclosan.

Aerobic soil metabolism studies represent degradation in the top layer of soil under oxygenated 

conditions. In the acceptable guideline aerobic soil metabolism study (MRID 47261401), 

triclosan was found to degrade rapidly and form the transformation product methyl triclosan 

(methoxy triclosan) at up to 17.5 % of applied parent triclosan. The half-lives of parent triclosan 

and methyl triclosan were 2.5-11 and 39-153 days, respectively. Three open literature studies

also provided supplemental and useable information on the persistence of parent triclosan but did 

not measure degradates. Estimates of persistence for parent triclosan were 5.9-8.9 days by Carr 

et al. (2011), 12.7-15.7 days by Xu et al. (2009), and 18 days by Ying et al. (2007). 

Ying et al. (2007) and Carr et al. (2011) open literature studies provide supplemental and useable 

information on the persistence of parent triclosan in the flooded, anaerobic, top layer of soil. The 

results of these studies appear to be contradictory because degradation was present in the Carr et 

al. (2011) study but not the Ying et al. (2011) study. However, differences in soil acclimatization 

between the two studies are believed by the agency to be the reason for these differences. The 

Carr et al. (2011) study used acclimatized soils to maximize degradation and the anaerobic halflives of parent triclosan were found to be 15.3-28.8 days. However in the Ying et al. (2007) 

study where the soils were not acclimatized, parent triclosan was observed to be stable to 

anaerobic degradation. Therefore, the agency considers the Ying et al. (2007) study to be more 

representative of the environment in general than the Carr et al. (2011) study because the lack of 

acclimated microorganisms in most anaerobic soils will create persistence or stability of 

triclosan. 

The anaerobic aquatic metabolism (835.4400) data requirement for triclosan has been waived as 

a result of the findings from the submitted open literature anaerobic soil metabolism studies 

(Carr et al., 2011 and Ying et al., 2007). Anaerobic aquatic metabolism studies represent the 

environmental fate of a compound under low oxygen conditions in sediment in the presence of 

water. It is reasonable to assume that a compound that is stable under anaerobic conditions in 

soil will also be stable in sediment. 

The acceptable guideline aerobic aquatic metabolism study (MRID 47261402) represents aerobic 

(oxygenated) surface water that is associated with sediment. Under aerobic conditions in a 

water and sediment system (total system), triclosan partitions from the water phase to the 

sediment phase by sorption. The water and total system half-lives were 1.2-1.4 days and 41-58 

days, respectively. No major or significant degradates (>10 % of applied triclosan) were 

detected. The minor degradate methyl triclosan was formed at 3.4-4.8 % of applied triclosan. 

The agency has received guideline studies for soil nitrification (OECD 216) and soil respiration 

(OECD 217) for triclosan. While these studies are considered to contain

supplemental information, no additional data are expected to be required. At up to 2 ppm 

(mg/kg) in soil, parent triclosan did not inhibit soil nitrification (MRID 47261403) or soil 

respiration (MRID 47261404).
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Table 16 - Metabolism of Triclosan with Formation of Degradates

Parameter Half-life of Triclosan (unless 

specified)

Source (Open literature unless 

specified)/

Study Classification/

Comments

Aerobic Soil Metabolism 

(OPPTS 835.4100, 162-1)

Gartenecker loam, 1.73 % OC, 

Swiss soil, 20 o

C

Speyer 5M, sandy loam, 1.39 % OC, 

German soil, 10 o

C

Speyer 5M, sandy loam, 1.39 % OC, 

German soil, 20 o

C

Senozoan clay loam, 1.04 % OC, 

French soil, 20 o

C

Half-lives

2.7 days (parent)

39 days (methyl triclosan)

11 days (parent)

Stable (methyl triclosan)

2.5 days (parent)

97 days (methyl triclosan)

3.3 days (parent)

153 days (methyl triclosan)

Adam, 2007; Guideline study MRID 

47261401/

Acceptable

Unknown triclosan source, purity 99.3 %

Methyl triclosan purity 99.6 %

Methyl Triclosan 

(Max of 13.4 % by 14 days, declining to 

4.2 % by 124 days(end of study)

Max of 14.5 % by 61 days, declining to 

13.3 % by 124 days

Max of 17.5 % by 28 days, declining to 

12.5 % by 124 days

Max of 24 % by 28 days, declining to 

17.3 % by 124 days

Loam soil, Study conducted at 22 oC 18 days in non-sterile loam 

soil

Stable in sterile loam soil

Ying et al., 2007; MRID 49197201/

SUPPLEMENTAL//

Triclosan from Fluka Chemicals, 

unknown purity

No degradate analysis

Loam soils, Temperature not 

specified

5.9 and 8.9 days in WWTPexposed and non-WWTP 

exposed loam soils

Stable in sterile loam soil

Carr et al., 2011; MRID 49197202/

SUPPLEMENTAL/

Triclosan from Sigma Aldrich Labs, >98 

% pure

No degradate analysis

Loamy sand, sandy loam, silty clay, 

and silt loam

Study conducted at 20 + 2 oC

13.6, 14.2, 12.7, and 15.7

days

Loamy sand, sandy loam, silty 

clay, and silt loam 

35.4 days in sterile loamy sand 

20 days in non-sterile loamy 

sand 

Xu et al., 2009; MRID 49159303/

SUPPLEMENTAL/

No degradate analysis

Anaerobic Soil Metabolism 

(835.4200, 162-2)

Loam soil, Study conducted at 22 o

C

Stable in non-sterile and 

sterile anaerobic loam soil

Ying et al., 2007; MRID 49197201/

SUPPLEMENTAL/

Triclosan from Fluka Chemicals, 

unknown purity

No degradate analysis
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Parameter Half-life of Triclosan (unless 

specified)

Source (Open literature unless 

specified)/

Study Classification/

Comments

Loam soil, Temperature not 

specified

28.8 and 15.3 days in WWTPexposed and non-WWTP 

exposed loam soils

Stable in sterile anaerobic 

loam soil

Carr et al., 2011; MRID 49197202/

SUPPLEMENTAL/

Triclosan from Sigma Aldrich Labs, >98 

% pure

No degradate analysis

Anaerobic Aquatic Metabolism 

(OPPTS 835.4400)

Waived Waived because Carr (2011) and Ying 

(2007) studies in soil support conclusion 

of stability in anaerobic aquatic sediment.

Aerobic Aquatic Metabolism 

(OPPTS 835.4400)

Pond Water

Pond Sediment

Pond System

River Water

River Sediment

River System

1.4 days (parent)

No significant degradates

56 days (parent)

Formation decline analysis 

based on sorption to sediment

58 days (parent)

Whole system

1.2 days (parent)

No significant degradates

56 (parent)

No significant degradates

Formation decline analysis 

based on sorption to sediment

41 days (parent)

Whole system

Adam, 2006; Guideline study MRID 

47261402, /Acceptable

Study conducted at 20 + 2 oC

Unknown triclosan source, purity 99.3 %

Methyl triclosan purity 99.6 %

Methyl triclosan formed at 3.4-4.8 % of 

applied triclosan

No significant degradates formed 

(>10 % of applied parent triclosan)

Soil respiration (OECD 217) No effect of triclosan 

treatments up to 2 ppm

Volkel, 2006, Guideline study/

MRID 47261403

Supplemental but no additional data

expected to be required

Soil nitrification (OECD 216) No effect of triclosan 

treatments up to 2 ppm

Volkel, 2007; Guideline study, MRID 

47261404/

Supplemental but no additional data 

expected to be required/

Ionization of Triclosan and Environmental pHs

Like most compounds with an acid ionizable functional group, triclosan will exist in both an unionized (protonated) and ionized (non-protonated) forms depending on the environmental pH 

range. The pH at which triclosan exists in even amounts (50 %) of both un-ionized and ionized 

forms is the pKa, which for triclosan is 8.14 at 20 o

C. While temperature variations can affect the 

amount of ionization by pH, 20 o

C is a representative environmental temperature and is relevant 
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for environmental risk assessment. At pH values that are one, two, and three units below the 

pKa, 90, 99, and 99.9 % of triclosan is expected to be in the un-ionized (protonated form). At 

pH values that are above the pKa, 90, 99, and 99.9 % of triclosan is expected to be in the ionized 

(non-protonated) state. The absence or presence or ionization is calculated by the HendersonHasselback Equation (http://chemistry.about.com/od/acidsbase1/a/hendersonhasselbalch.htm). 

Typical soil pH values range from pH 5 to 7 in more humid areas, while soils in more arid areas 

can range up to pH 9. Therefore, 90-99 % of triclosan in soil is expected to be present in the 

non-ionized form in more humid areas and up to 90 % may be present in the ionized form in arid 

areas. Table 17 below provides information on the extent of non-ionization/ionization of 

triclosan by pH. 

Table 17 - Effect of pH on the Ionization of Triclosan at 20 o

C

pH Non-Ionized 

Triclosan (%) Ionized Triclosan (%)

5.14 99.9 0.1

6.14 99 1

7.14 90 10

8.14 (pKa) 50 50

9.14 10 90

Leaching-Adsorption-Desorption (835.1230)

The agency is aware of three open literature leaching-adsorption-desorption studies for triclosan

(Xu et al., 2009; Cha and Cupples, 2010; Duran-Alvarez et al., 2012). The Xu et al (2009) study

was reviewed and classified as supplemental information. The results indicate that parent 

triclosan is strongly sorbed to soil. The remaining studies by Cha and Cupples (2010) and 

Duran-Alvarez et al., (2012) have not been reviewed but the agency anticipates reviewing these 

studies prior to the risk assessment. 

Table 18 below contains the leaching and adsorption-desorption data for triclosan. The extent of 

sorption to soil in the presence of water will depend on the environmental pH and the degree of 

non-ionization/ionization of triclosan (Thompson and Goyne, 2012). The hydroxyl functional 

group of triclosan will carry a neutral charge in more humid areas with lower pH values and a 

negative charge in arid areas with high pH values. Because soil has a negative charge, sorption 

will decrease as the pH of the soil increases.
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Table 18 - Leaching and Adsorption-Desorption of Triclosan to Soil and Sediment

Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

Leaching-Adsorption-Desorption 

(OPPTS 835.1230, 163-1)

Kd values of 9.7, 133, 273, 

and 52 ml/g

Koc values of 2,188, 23,988, 

8,709, and 3,631 ml/g in 

loamy sand, sandy loam, silty 

clay, and silt loam soils 

Xu et al., 2009; MRID 49159303

SUPPLEMENTAL/

Study conducted at 20 + 2 oC

Kd values of 33, 55, and 51 

ml/g in loamy sand, sandy 

loam, and sand soils

Koc values of 5,613, 6,310, 

and 3,968 ml/g

Cha and Cupples, 2010; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Sorption coefficients (Kd) for 

triclosan in the smectite-based 

(shrink-swell) silty clay 

topsoil and clay subsoil

Kd values for triclosan were 

64.9 ml/g and 19.2 ml/g, 

respectively. Triclosan 

sorption was irreversible. 

The organic carbon content of 

the soils and sludge were 2.5, 

1.8, and 181 mg/g with a pH 

range of 8.0-8.1 for soil and 

7.6 for sludge. The preexisting triclosan 

concentrations were 9.7, 6.3, 

and 1,401 ng/g or ng/l, 

respectively.

Duran-Alvarez et al., 2012; No MRID 

assigned/

Quality unknown, study not formally 

reviewed.

Terrestrial Field Dissipation, Leaching, Runoff, and Crop Uptake (835.6100)

Triclosan has been commonly detected in sewage sludge both in the United States and in other 

countries. As a result triclosan may potentially be applied to agricultural fields as a contaminant 

of sewage sludge land applications. Triclosan input from EPA registered pesticidal use patterns 

is expected to be primarily from industrial uses in textile manufacturing and would therefore 

have limited geographic impact. The geographically-widespread nature of the detections in the 

environment indicates that that while the EPA registered antimicrobial uses may potentially 

contribute to the exposure in some localized areas with industrial sources, the primary 
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contribution is expected to be from the personal care product uses. The agency is aware of 14

field dissipation studies from the open literature; these are listed in Table 19. None of these 

studies have been reviewed by the agency, but they will be reviewed during the risk assessment 

phase to determine their usefulness in the risk assessment. Some of the studies appear more than 

once in the table because they contain information on overall environmental fate and not just 

dissipation. 

Table 19 - Terrestrial Field Dissipation, Surface Runoff, Leaching, and Crop Uptake

Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

Degradation in sewagesludge amended soils (no 

guideline number)

Half-lives of 0.4-12.5 and 0.6-7 days 

in sandy loam soil

Degradation faster in liquid 

municipal biosolids than in dewatered municipal biosolids

Al-Rajab et al., 2009/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Canada

No characterization of significant nonextractable residues

Half-lives of 13.6, 14.2, 12.7, and 

15.7 days in loamy sand, sandy loam 

silt loam, and silty clay soils

Xu et al., 2009/

No MRID assigned

Quality unknown, study not formally 

reviewed.

No degradate analysis

Half-lives of 29-83 days for loamy 

sand, sandy loam, and sandy soils

After 100 days, 21-25, 16-43, and 

20-45 % of triclosan remained

Cha and Cupples, 2010/

No MRID assigned

Quality unknown, study not formally 

reviewed.

No degradate analysis

Half-life and 90 % dissipation of 23 

and 77 days 

LOQ was reached by 111 days 

Topp et al., 2008/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Ontario, Canada

Silt loam soil with wheat stubble

No degradate analysis

Triclosan at up to 100 mg/kg (ppm) 

did not affect the degradation of 

estrogen molecules 

The half-lives for 10 and 100 mg/kg 

triclosan were about 14-days but 

1,000 ppm rate did not reach half-life 

Total degradation of estrogens by 14

days at 10-100 mg/kg triclosan

Limited degradation of estrogens at 

1,000 mg/kg triclosan

Shareef et al., 2009/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Australia

Sandy soil
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Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

Topp et al., 2008/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Australia

Sandy soil

Surface runoff from treated 

soil

Runoff concentrations of 26 and 258 

ng/l from injected and surfaceapplied liquid sludge 

/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Tile drainage concentrations Triclosan present in water for 9 

months.

Maximum concentration of 230 ng/l 

in tile water. 

Sewage concentrations of 240-3,680 

ng/l in 2005 and 2006

Bester and Schafer, 2009

/

No MRID assigned

Quality unknown, study not formally 

reviewed.Kd of 160 ml/g

Triclosan Maximum concentration of 

14,000 ng/g in treated soil 

reached 74 ng/l in tile water. 

There was no measurable crop 

uptake in wheat.

Edwards et al., 2012/

Edwards et al., 2009bNo MRID assigned

Quality unknown, study not formally 

reviewed.

Field dissipation, leaching, 

and crop uptake

Triclosan reached 74 ng/l in tile 

drainage at 3,676 ng/l from surface 

application

There was no measurable crop 

uptake in tiles

Lapen et al., 2012

No MRID assigned

Ontario, Canada

Quality unknown, study not formally 

reviewed.

Leaching in sludge-treated 

fields (no guideline)

Triclosan detected in tile drainage at 

150 ng/l

Up to 2.2 % of applied triclosan in 

leachate (max in sandy loam soil)

Lapen et al., 2010/

2.1 % OC, Clay loamNo MRID assigned

Quality unknown, study not formally 

reviewed.

No degradate analysis

Soil columns from MexicoTriclosan 

concentrations in UK.

Up to 2.2 % of applied triclosan in 

leachate (max in sandy loam soil)

Gibson et al., 2012/

No MRID assigned

Quality unknown, study not formally 

reviewed.Soils in Mexico treated with 

sludge repeatedly for 10-90 years and 

cropped
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Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

Sorption coefficients (Kd) for

triclosan present in top 10 cm as 

either parent compound or methyl 

triclosan were 64.9 ml/g and 27-42 % 

methyl triclosan).

The organic carbon content of the 

soils and sludge were 2.5, 1.8, and 

181 mg/g with a pH range of 8.0-8.1 

for soil and 7.6 for sludge. The preexisting triclosan concentrations 

were 9.7, 6.3, and 1,401 ng/g or ng/l, 

respectively.

Butler et al., 2012/

No MRID assigned

Quality unknown, study not formally 

reviewed.

Sandy clay loam Half-life of 182-193 days

Detectable residues (>56 ng/g) up to 

858 days in outdoor pots

Walters et al., 2010/

No MRID assigned

Quality unknown, study not formally 

reviewed

U.S. soils with high treatment rate

Environmental Monitoring Studies for Triclosan 

Triclosan has been detected in surface water and sediment. The geographically-widespread 

nature of the detections in the environment indicates that that while the EPA uses may contribute 

to the exposure in some localized areas with industrial sources, the main contributor is the 

personal care product uses in most areas without industrial sources21. Surface water and 

sediment exposure most likely result from the effluent from WWTPs which contains small 

amounts of triclosan relative to the portion that is sorbed onto sewage sludge. The studies cited 

below in Table 20 demonstrate that triclosan is typically found in water in the ng/l (parts-pertrillion, ppt) concentration range and in sediment in the ng/g (parts-per-billion, ppb) 

concentration range. There were 17 articles for surface water occurrence, five for finished 

reclaimed wastewater and ground water, and one for bottom sediment. The higher detections in 

surface water and bottom sediment and the lower concentrations in the landfill leachate and wells 

are consistent with the fact that triclosan has a limited water solubility (12 mg/l) and appears to 

be strongly sorbed to soils and sediments. The Buth (2010) article also contains information on 

 21 According to the 200-2005 Kline Report around 120,000 pounds of triclosan are used annually for antimicrobial 

pesticidal uses; this makes up less than 1% of the overall annual production of triclosan in the U.S. of around 10 

million pounds (Kline, 2005). 
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the relative amounts of the chlorinated triclosan transformation products formed in the 

environment. None of these studies have been formally reviewed, but will be reviewed during

Registration Review to determine their usefulness in risk assessment. 

Table 20 - Environmental Monitoring Studies for Triclosan

Medium Range Unit Average Median No. 

Samples

No. 

Detections

Percent 

Detection

References (Open literature study 

unless specified)/ 

Study Classification/

Comments 

Surface 

Water

0.01-2.3 ng/l 0.19 0.05 85 45 53 

Barnes et al., 2002; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Various streams in U.S., USGS 

<3-10 ng/l NA NA NA NA NA

Bester (2005); No MRID assigned/

Quality unknown, study not formally 

reviewed/

Ruhr River Catchment in Germany

1.6-29 ng/l 10.9 12.4 29 21 72

Boyd et al, 2004; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Stormwater canals and Bayou St. John 

in New Orleans

60-80 ng/l 70 70 3 2 66

Coogan et al, 2007; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Denton, TX

0.398-

1.02 ng/l 0.627 NA 2 2 100

DeLorenzo et al, 2008; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Toxicity of triclosan and formation of 

methyl triclosan in estuarine systems,

USGS.

4.9-13.7 ng/l 7.5 NA 13.7 13.7 100

Fair et al, 2009; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Estuarine water in Charleston Harbor
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Medium Range Unit Average Median No. 

Samples

No. 

Detections

Percent 

Detection

References (Open literature study 

unless specified)/ 

Study Classification/

Comments 

0.021-1 

(RL=1) ng/l

0.89 

(includes 

ND)

1 5 47 10.6

Focazio et al., 2008; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

49 locations

18 states and Puerto Rico

Unfiltered samples USGS

110-640 ng/l NA

200 and 

110 for 

1st and 

second 

downstream 

locations

10 for 

each 

location

6

7 60-70 

Glassmeyer et al., 2005; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Downstream of 10 WWTPs, USGS

2,300 

(maximum) ng/l 176 50 145 90 62

Kolpin et al, 2002; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Streams with minimal dilution

Unfiltered water samples, USGS

10-4,010 ng/l 193 186 36 36 100

Lishman et al., 2006; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Thames River, Canada 

12 WWTP plants in Canada with 

1,215-105,000 m3/day treated input.

Lagoon, activated sludge, and activated 

sludge/ filtration treatments

35-100 % residential 

70-650 ng/l NA NA NA NA NA

Poiger et al., 2003 and Linstrom et al., 

2002; No MRID assigned/

Quality unknown, study not formally/

34-92 % removal

p. 172 of Australia Report

12 ng/l 12 12 3 1 33

Vanderford and Snyder, 2006; No 

MRID assigned/

Quality unknown, study not formally 

reviewed/

Stream with >90 % treated wastewater

4o treatment
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Medium Range Unit Average Median No. 

Samples

No. 

Detections

Percent 

Detection

References (Open literature study 

unless specified)/ 

Study Classification/

Comments 

0.4-85 

(dry 

weight)

ng/g N/A N/A 24 24 (>0.4 ng/l) 100

Venkatesan et al., 2010; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Sediment in Minnesota freshwater 

bodies

58 % of samples downstream of 

WWTPs were greater than upstream

1-9

26

ng/l

ng/g

3 water

26 sediment

NA

41 water

12 sediment

12 NA

Wilson et al, 2009; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Lower Hudson River Estuary 

1,130 

(maximum)ng/l NA NA 14 9 64

Young et al, 2008; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Baltimore City and County watersheds

9-60 % removal

193 ng/l NA NA 4 1 25

Yu and Chu, 2009; No MRID assigned/

Quality unknown, study not formally 

reviewed

West Prong Little River, East 

Tennessee

Finished 

Reclaimed 

Waste 

Water and 

Ground 

Water

0.021-1 

(RL=1) ng/l

0.89 

(includes 

ND)

1 47 5 10.6

Barnes et al., 2008; No MRID assigned/

Quality unknown, study not formally 

reviewed/

25 samples in 12 states and Puerto Rico

441 wells sampled, USGS

<1.0 NA NA NA 5 3 60

Buszka et al, 2009; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Leachate from landfills in GW in 

Indiana, USGS

No 

detection

s

NA NA NA 11 0 0

Katz and Griffin, 2008; No MRID 

assigned/

Quality unknown, study not formally 

reviewed/

Compounds in Karst water in Florida
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Medium Range Unit Average Median No. 

Samples

No. 

Detections

Percent 

Detection

References (Open literature study 

unless specified)/ 

Study Classification/

Comments 

280-

2,110 ng/l 1,430 NA 6 3 50

Loraine and Pettigrove, 2006; No 

MRID assigned/

Quality unknown, study not formally 

reviewed/

Reclaimed wastewater in California

Bottom 

Sediment

4-10

13-14

ng/g

10 (1998)

4 (2008)

13.5 

(1998-

2003)

10 

(1998)

4 (2008)

13.5 

(1998-

2003)

2 2 100

Buth et al., 2010; MRID 49159302/

Quality unknown, study not formally 

reviewed/

Concentrations of 4-chloro triclosan, 6-

chloro triclosan, and 4,6-dichloro 

triclosan reached 1-80 pg/g in 

Mississippi River (most<20 pg/g)

50-85 pg/g for 2,8-DCDD

Up to 4 pg/g for others in Lake Pepin.

Triclosan

Mississippi River sediment in 

Minnesota, and Lake Pepin sediment 

triclosan concentrations, respectively

Bioconcentration in Fish (835.1730) and other Aquatic Organisms

Triclosan and its transformation product methyl triclosan have been detected in fish, snails, 

dolphins, and algae in both freshwater and brackish/salt water (Table 21). Acceptable studies for 

bioconcentration in fish (850.1230) and in oysters (850.1710) are still needed because none have 

been submitted to the agency and in general the information in the open literature appears to be 

correlative in nature but do not provide a bioconcentration values which can be used in a 

quantitative risk assessment. The agency required the bioconcentration in fish and oyster studies 

as part of the post-RED DCI. Triclosan and methyl triclosan are likely to accumulate in aquatic 

organisms because the log P (log Kow) values are 4.76 and 5.2 (>3, level of concern for 

bioconcentration and bioaccumulation), respectively, and both compounds will need to be 

addressed in each study. The field monitoring studies in Table 21will be reviewed to gain any 

additional information that may be used for risk characterization. 
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Table 21 – Biological Field Monitoring of Aquatic Organisms 

Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

BCF (ratio of 

organism 

concentration to 

water 

concentration) 

(OPPTS 

850.1730, 165-4)

Concentration range of 10,687-16,492 and 

51,041-92,504 ng/g for triclosan and methyl 

triclosan, respectively.

Triclosan detected in few fish samples

Concentration in bream has increased since 

1990’s

Methyl triclosan detected in all.

Boehmer et al., 2004; No MRID assigned

Quality unknown, study not formally reviewed/

Methyl triclosan studied

German Rivers

Triclosan detected at 0.24-4.4 ug/g in fish 

upstream of STP

35-120 ug/g in caged fish in sewage waste

Triclosan detected at 14-80 ug/ml of bile 

No evidence of estrogenic activity

Houtman et al., 2004; No MRID assigned/

Quality unknown, study not formally reviewed/

Netherlands

No degradates analyzed

Bottlenose dolphins (Tursiops truncatus) 

0.12-0.27 ng/g (mean of 0.18 ng/g) with 31 

% detection frequency at Charleston. 

Influent and effluent concentrations of 

2,800-3,400 and 190 ng/l at Charleston, SC.

Bottlenose dolphins (Tursiops truncatus)

0.025-0.11 ng/g (mean of 0.072) with 23 % 

detection in Florida. Charleston estuarine 

concentrations were 4.9-14 ng/l (7.5 ng/l 

average).

Fair et al., 2009; No MRID assigned/

Quality unknown, study not formally reviewed/

United States

No degradates analyzed

Methyl triclosan was detected in all 29 male 

common carp (Cyprinus carpio) from Las 

Vegas Bay with a mean concentration of 

596 ng/g wet weight. The halogenated 

analogs were detected less frequently 

(21%–76%) and at much lower 

concentrations (<51 μg/g ww)

Leiker et al., 2008; No MRID assigned/

Quality unknown, study not formally reviewed/

United States, USGS

Methyl triclosan

BCF value of 1.7X in Mediterranean mussel 

(Mytilus galloprovincialis)

30-day concentration of 461 ng/g dry 

weight of triclosan in 300 ng/l

Depuration half-life of 12 days—slower 

than uptake rates

Gatidou et al., 2010; No MRID assigned/

Quality unknown, study not formally reviewed.

Greece
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Parameter Value

Source (Open literature study unless 

specified)/

Study Classification/

Comments

Bioconcentration 

in snails and algae 

(no guideline)

Triclosan concentrations of 112, 59,000, 

and 162,000 ppt in water, snails, and algae

BCF values of 500 and 1,400 in snails and 

algae.

Methyl triclosan concentrations of 0.041, 

50, and 50 ppb in water, snails, and algae

BCF values of 1,200 in snails and algae

Methyl triclosan concentrations of 4.2-365 

ng/g lipid in different fish (most <100 ng/g)

Coogan and LaPoint, 2008; No MRID 

assigned/

Quality unknown, study not formally reviewed/

United States

Methyl triclosan

Dissertation at: 

http://digital.library.unt.edu/ark:/67531/metadc

3986/m2/1/high_res_d/dissertation.pdf

Wastewater Treatment Studies

Activated Sludge, Respiration Inhibition

The agency is anticipating requiring activated sludge respiration inhibition (ASRI) data because 

of the potential for triclosan to be discharged to WWTPs and affect the microbial components of 

WWTPs receiving effluent from textile and fabric materials preservative uses. ASRI data allows 

the agency to evaluate the potential hazard to such systems from triclosan loading.

Activated Sludge, Sorption Isotherm

The agency is assuming a removal of 80 % for parent triclosan by sorption to activated sludge 

based on the results of Lee et al. (2003). This literature study measured triclosan concentrations 

in water in WWTPs before and after sludge sorption, and average percent removal was 80 %.

Biotic Degradation

The agency has received data for the dissipation of triclosan under WWTP conditions. The 

acceptable guideline WWTP guideline studies for the environmental fate of triclosan

(Christensen 1994a and 1994b) demonstrate the degradation of triclosan under aerobic 

conditions with a half-life of 5.2 days in aerobic sludge, but also demonstrate the lack of 

degradation under anaerobic conditions. The unreviewed Behera (2010) literature study on 

sorption to activated carbon may be representative of the sorption to activated sludge, and the 

appropriateness and usefulness of the study will be addressed prior to risk assessment. Table 22

contains the results of WWTP studies for triclosan. 
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Table 22 WWTP Studies for Triclosan

Parameter Half-life of Triclosan (unless 

specified)

Source (Open literature unless 

specified)/

Study Classification/

Comments

Simulation Tests to Assess the 

Primary and Ultimate 

Biodegradability of Chemicals 

Discharged to Wastewater (OCPPS

835.3280)

Stable in anaerobic sludge Christensen, 1994a; Guideline study, 

MRID 47261406/

Acceptable

Simulation Tests to Assess the 

Primary and Ultimate 

Biodegradability of Chemicals 

Discharged to Wastewater (OCPPS 

835.3280)

5.2 days in aerobic sludge Christensen, 1994b; Guideline study, 

MRID 47261407/

Acceptable/

57.1 % CO2 evolution by 57 days

10.2 % organic volatiles by 57 days

Sorption to Activated Carbon (no 

test guideline)

Freundlich Kf values of 1.13-

3.03 million

Behera et al., 2010; No MRID assigned/

Quality unknown, study not formally 

reviewed/

Environmental Exposure from Textile Impregnation Facilities

The agency as part of the post-RED DCI required field monitoring studies (sent on October 5, 

2011, # GDCI 054901-30197)) for EPA registered uses in plastic and textile manufacturing 

facilities. The technical manufacturing label was modified to limit use in plastic manufacturing 

to those where the plastic does not come into contact with water during manufacturing. Based 

on this label change there should be no environmental exposure from use at plastic 

manufacturing facilities and the field monitoring requirement was dropped. The registrants 

submitted an acceptable textile monitoring study in response to the post-RED DCI (MRID 

48858101). Two textile facilities were chosen to collect data on the concentrations of triclosan 

and methyl triclosan present in their effluent wastewaters after triclosan was applied to textiles 

using the exhaustion process (Table 23). This process uses a jet machine to apply triclosan and 

other ingredients to textiles at high temperature. At the two facilities selected the spent or 

remaining solution from the exhaustion process is discharged to the on-site wastewater treatment 

plants before the resulting effluent is discharged to surface waters. Monitoring specifically at 

facilities that have their own treatment facilities allows better identification of triclosan 

attributable to its material preservative use from FDA uses. The discharge to surface waters at 

these facilities is conducted under National Pollutant Discharge Elimination System (NPDES) 

permits. 

In order to obtain good sample regimes, it was determined that for facility 1, stable operations 

could possibly be achieved in 2 to 3 weeks following the initiation of the production run. It was 
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further noted that stable effluent concentration of the active attained peak concentration in 7 day 

cyclic fashion consecutively.

For facilities 1 and 2, the best sample regime was obtained through a 5 consecutive, 24 hour 

composite effluent samples.

In all 22 samples were analyzed for presence and quantification of triclosan and methyl triclosan 

for both facilities. The average and maximum triclosan and methyl triclosan concentrations in 

effluent and in-stream under 7Q10 conditions are listed in Table 23 

Table 23 - Textile Monitoring Facility Characteristics

Application/ 

Parameter/ 

Characteristics 

Facility # 1 Facility # 2 Comments

Use pattern Intermittently used Constantly used -

Number of days each 

facility was processing

textiles in study period

327 pounds 636 pounds -

WWTP effluent flow 

rates (MGD)

Min: 0.09, Avg: 0.21, 

Max:0.7

Min:1.04, Avg: 1.47, 

Max: 1.81 -

Hydraulic retention 

time (days)

Min: 13, Avg: 43, Max: 

100 Min:6, Avg: 7, Max: 10 -

Aeration lagoon 

volume (MG) 2.25 2 EQ Basin for Fac#2

Aeration lagoon 

MLSS 2500 mg/L 3.8 Aeration lagoon 1 & 2

Clarifier volume 

(MG)

0.147MG 0.021 MG Mixed/Floc tank

Polishing pond 

volume (MG) 6.5 0.542 Clarifier 1

Polishing pond depth 4 ft 0.542 MG Clarifier 2

Polishing pond area 5 acres each 0.033382 MG Post Aeration

Avg: average; MG: million gallons; MGD: million gallons per day; Min: minimum; Max: 

maximum

Table 24 - Textile Triclosan and Methyl Triclosan Monitoring Concentrations

Analyte Average (μg/L) Maximum (μg/L)

Triclosan Facility 1 0.099 0.190

Triclosan Facility 2

Triclosan Facility 1 IWC 0.0032 0.0061

Triclosan Facility 2 IWC 0.0331 0.0432

Methyl triclosan: Facility 1 

and Facility 2 <0.0018 <0.0018

IWC: in-stream waste concentration (based on NPDES 7Q10 flow).
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APPENDIX C: Ecotoxicity Profile

Terrestrial Organisms 

Birds 

The requirement for acute oral toxicity data for triclosan is satisfied. An acute oral toxicity study 

using the technical grade of the active ingredient (TGAI) is used to establish the toxicity of 

triclosan to birds. The preferred test species is either the mallard (Anas platyrhynchos) or the 

northern bobwhite (Colinus virginianus). Three studies have been submitted (Table 24). One 

study each with the mallard and northern bobwhite with TGAI categorize triclosan as being 

slightly to practically nontoxic to birds (LD50 values = 825 and >2150 mg ai/kg bw/day, 

respectively). A formulation containing 3.89% ai was found to be practically nontoxic (northern 

bobwhite LD50 >2000 mg ai/kg bw/day).

The requirement for subacute dietary toxicity data for triclosan is satisfied. A subacute dietary 

study using the TGAI is required on a case-by-case basis depending on the results of lower-tier 

ecological studies and pertinent environmental fate characteristics in order to establish the 

toxicity of a chemical to avian species. The results of two subacute dietary toxicity studies, 

submitted for triclosan, are provided in Table 24, one with triclosan (99.7% ai) and one a 

formulation of triclosan (3.89%). An LC50 of greater than 5000 ppm ai categorizes triclosan as 

practically nontoxic to birds on an acute dietary basis.

For the triclosan use patterns chronic exposure is not considered likely, so an avian reproductive 

study is not expected to be required at this time. 

Table 25 - Toxicity of Triclosan to Birds

Species

Chemical,

% Active 

Ingredient

(ai)

Endpoint Toxicity 

Category

Study 

Classification/

Source/

Comments

Mallard duck

(Anas 

platyrhynchos), 19 

weeks old

Triclosan

99.7%

LD50 >2143 mg ai/kg-bw

NOAEL > 2143 mg ai/kg-bw

Relatively 

nontoxic

Acceptable/

Pedersen and 

Helsten, 1993a 

MRID 43022603/

- 14-day test duration

Bobwhite quail

(Colinus 

virginianus), 21 

weeks old

Triclosan

99.7%

LD50 = 822 mg ai/kg-bw

NOEL = <147mg ai/kg-bw 

(diarrhea, lethargy)

Slightly toxic

Acceptable/

Pedersen and 

Helsten, 1993b 

MRID 43022602/

- 14-day test duration
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Species

Chemical,

% Active 

Ingredient

(ai)

Endpoint Toxicity 

Category

Study 

Classification/

Source/

Comments

Bobwhite quail

(Colinus 

virginianus), adults

Triclosan 

(Issue Plus II)

3.89%

LD50 > 77.8 mg ai/kg-bw

(LD50 > 2000 mg f/kg-bw)

NOAEL >77.8 mg ai/kg-bw

(NOAEL > 2000 mg f/kg-bw)

No mortality or sublethal 

effects

Formulation 

is Relatively 

nontoxic

Acceptable for 

formulated product/

Terrell, 1989a MRID 

41008910/

Bobwhite quail

(Colinus 

virginianus), 13 days 

old

Triclosan

99.7%

LC50 (diet) >4985 ppm ai

(LC50 (diet) > 5000 ppm f)

(at highest treatment 40% 

mortality, 95% CI 12.1 –

73.8% mortality)

NOAEC = 1246 ppm ai

(mortality)

Relatively 

nontoxic

Supplemental/

Pedersen and 

Helsten, 1993c 

MRID 43022604/

- 8-day test duration 

(5 days exposed, 3 

days post exposure)

Bobwhite quail

(Colinus 

virginianus), 7-10 

days old

Triclosan

(Issue Plus II) 

3.89%

LC50 (diet) > 194 ppm ai

(LC50 (diet) > 5000 ppm f)

NOAEC = N.R.

No mortality or sulblethal 

effects at limit dose

Formulation 

is Relatively 

nontoxic

Acceptable/

Terrell, 1989b MRID 

41008911/

- 8-day test duration 

(5 days exposed, 3 

post-exposure)

Mammals 

Wild mammal testing is higher tier effects testing and is not typically required by the agency. In 

most cases, rat toxicity values obtained from studies conducted to support data requirements for 

human health risk assessments substitute for wild mammal testing. Acute oral toxicity and twogeneration rat reproduction data are available for triclosan. Refer to Appendix A, Toxicology 

Profile, of this document for a description of laboratory mammalian toxicity data. Information

about triclosan’s potential as an endocrine disruptor is also described in Appendix A.

Based on submitted mammalian data triclosan is considered practically nontoxic to mammals on 

an acute basis (rat LD50: >5000 mg ai/kg-bw; MRID 432069-01). The 

reproductive/developmental NOAEL is l000 ppm (50 mg ai/kg-bw/day; MRID 406237-01). No 

additional mammalian data are expected to be required at this time to conduct a risk assessment 

for mammalian wildlife.
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Nontarget Beneficial Terrestrial Insects 

The triclosan use patterns are not expected to result in exposure of nontarget beneficial terrestrial 

insects. Data are not expected to be required for the triclosan uses. 

Toxicity to Aquatic Receptors

In the water column triclosan is highly acutely toxic to freshwater fish and invertebrates, and also 

has a detrimental impact on reproduction in the parts per billion range (Table 25). One available 

subchronic sediment toxicity study indicates that triclosan does not adversely impact survival, 

emergence or development rate of freshwater benthic invertebrates (Table 25). Acute and 

chronic data are lacking for estuarine/marine fish and crustaceans but are needed for risk 

assessment. Prediction models were run to obtain estimates of triclosan toxicity for 

estuarine/marine fish and a shrimp. Acute data is also lacking for an estuarine/marine mollusk. 

A study is expected to be required.

Freshwater Fish and Amphibians-Triclosan

For triclosan, material preservative uses, an acute toxicity study with a coldwater and a warm 

water species, and a chronic test using the TGAI is used to establish the toxicity of triclosan to 

freshwater fish. The preferred acute test species are rainbow trout (Oncorhynchus mykiss) and 

bluegill sunfish (Lepomis macrochirus). Because there is potential for endocrine effects, a fish 

full life cycle rather than an early life stage is used to establish chronic reproductive effects from 

triclosan. Acute toxicity for the species tested in the fish full life cycle test is used in the

calculation of an acceptable acute-to-chronic ratio (ACR) to extrapolate the chronic value for the 

most acutely sensitive fish species. Effects data for fish are generally used as surrogate data for 

amphibians. When amphibian data is available it is used within the risk assessment. For 

triclosan because it can exist in unionized and ionized states at environmentally relevant pHs 

(pKa is around 7.9-8.1), a relationship of toxicity with pH is desirable which means testing of the 

same species under different pH conditions. However as an alternative, studies conducted under 

pH conditions that optimize the unionized state, which is generally considered the more 

bioavailable and toxic state, would be conservatively used to represent toxicity at higher more 

alkaline conditions under which the ionized form would dominate.

A rainbow trout (cold water species) and a fathead minnow (warm water species) study with 

technical grade triclosan were submitted to the agency to support registration (Table 25). Both 

studies are classified as Supplemental information. The rainbow trout study was originally 

classified as an Acceptable study but upon further examination of the stability of triclosan it 

declined by over 50% during the exposure period which is not sufficiently stable. From other 

similar studies triclosan needs frequent replacement such as flow-through conditions to ensure 

stable exposure concentrations. Values based on nominal or average measured concentrations 

potentially underestimate sensitivity to triclosan.
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There are several acute freshwater fish and amphibian studies in the open literature, a 

preliminary list of public literature obtained by the Office of Water and provided to AD is 

provided in Table 26. The agency has started but not completed the review of these data for use 

in performing the risk assessment. As discussed in Section 4.4 Effects Analysis Plan, a search of 

the public literature for triclosan effect studies and a review of the relevant studies found is 

planned as part of the risk assessment phase. There are a limited number of open literature 

studies that have been reviewed at this point. Public literature that has previously been reviewed 

are studies looking at endocrine effects using Japanese medaka, a non-native North American 

species and these results are summarized in Table 25. In the Foran, Bennett, and Benson (2000) 

study the control results are not reported and without this information the study quality cannot be 

verified and is therefore Unacceptable at this time. In the other reviewed study, Ishibashi et al

(2004), the reported triclosan concentrations were not sufficiently stable (decline >30%) over the 

renewal period. Acute toxicity values range for the Supplemental studies from 260 μg ai/L for 

the fathead minnow (Pimephales promelas) to 602 μg ai/L for the Japanese medaka. While there 

is uncertainty in the use of this data because of the instability of triclosan, the measured 

concentrations at the end of the renewal period can be used to provide a reasonable lower bound 

so at this time no additional acute data is being required.

A number of the studies in the open literature in Table 26 are identified as conducted under static 

conditions with no analytical measurements of triclosan concentrations and are therefore not 

suitable for use in a risk assessment.

Three additional acute studies were conducted with a triclosan formulation, Issue Plus II, one 

study with Zebrafish which was found to be Unacceptable and one study each with rainbow trout 

and bluegill sunfish.

No chronic data have been submitted by the registrant. There are several early life stage 

freshwater fish studies in the open literature, a preliminary list of public literature obtained by the 

Office of Water and provided to AD is provided in Table 28. The agency has started but not 

completed the review of these data for use in performing the risk assessment. In this case to 

establish chronic toxicity, a fish full life cycle test is used to address endocrine effect concerns

on reproduction. 

As discussed in Section 4.4, the Effects Analysis Plan, a search of the public literature for 

triclosan effect studies and a review of the relevant studies found is planned as part of risk 

assessment phase of registration review. There are two open literature studies looking at the 

potential for endocrine effects that have been reviewed and these are listed in Table 27. Both 

studies were conducted using Japanese medaka (Oryzias latipes). The first study reported was 

with Japanese 2 day post-hatch medaka fry (Oryzias latipes) which were exposed for 14 days to 

triclosan (1, 10, 100 ppb) (Foran, Bennett, and Benson, 2000). While there was a solvent control 

included in the experimental design there was no negative control so effects of the solvent on 

study results cannot be discounted. No significant effects on sex ratio or on female phenotypic 

sex characteristics as measured by sexually dimorphic fin shape and size were observed up to the 
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highest concentration tested, 100 ppb (nominal). There was a significant increase in fin size in 

males at the highest concentration tested. Foran, Bennett, and Benson (2000) concluded that 

while there was no statistically significant effect on sex ratio there appeared to be a weak trend 

of increasing males with increasing triclosan concentration and taken with the increased male fin 

length at the highest concentration suggested that triclosan could be weakly anti-estrogenic/ 

androgenic. There are statistical tests that can better evaluate the existence of a trend than the 

tests used. The data in the journal article are insufficient to independently conduct such an 

analysis. Additionally triclosan was toxic at 100 ppb, significantly reducing the number of 

animals as compared to lower treatment levels. The later work with mature Japanese medaka by 

Ishibashi et al. (2204) also showed that triclosan has high toxicity on the early life stages (100% 

mortality (96-h LC50 399 ppb, nominal; NOAEC for 156 ppb for hatching success and time-tohatch). When the medaka were exposed to triclosan at 20, 100 and 200 ppb nominal (8.3, 46.4, 

112 ppb average measured concentrations, respectively, prior to renewal at 24 hours), there was 

a significant reduction in the length of F0 females relative to control. A metabolite of triclosan 

may be a weak estrogenic compound with the potential to induce vitellogenin in male medaka 

but with no adverse effect on reproductive success and offspring (Ishibashi, et. al., 2004). None 

of the studies are full life cycle tests and a fish full life cycle study is expected to be required.

Freshwater Invertebrates-Triclosan

For triclosan, material preservative uses, an acute and chronic toxicity study with Daphnia 

magna or Daphnia pulex using the TGAI, is used to establish the toxicity of triclosan to 

freshwater invertebrates. Three acute studies with D. magna using technical triclosan (>98% ai) 

have been submitted. One of the studies upon review was classified as unacceptable because 

measured triclosan concentrations were highly erratic and therefore actual exposure 

concentrations were not evident (MRID 42322102). The other two studies are classified as 

supplemental (MRID 43046002 and 43740701). Both of these two studies were conducted as 

static tests. Because in one of these studies triclosan was not measured at all treatment levels, a 

definitive EC50 could not be reasonably determined (MRID 43740701). For this study the test 

only establishes a 48-h EC50 as >139 ppb ai from measured data, which is not an acceptable limit 

test (i.e., >100,000 ppb ai or limit of triclosan solubility whichever is lower). In the remaining

study (MRID 43046002),) measured concentrations showed triclosan was not stable and while a

48-h EC50 of 390 ppb ai based on nominal concentrations was reported, use of this value will 

underestimate sensitivity and risk. A value based on measured data will be developed from the 

data and used within the assessment unless alternative data from the open literature is found to be 

acceptable and more sensitive. The data categorize the TGAI (99.7% ai) as being highly toxic to 

invertebrates (48-h EC50 = 390 μg ai/L). 

There is no acceptable chronic data submitted for invertebrates. A life cycle study is expected to 

be required.
Docket Number: EPA-HQ-OPP-2012-0811

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For triclosan because it can exist in un-ionized and ionized states at environmentally relevant 

pHs (pKa is around 7.9-8.1), a relationship of toxicity with pH is desirable which means testing 

of the same species under different pH conditions. However as an alternative, studies conducted 

under pH conditions that optimize the unionized state, which is generally considered the more 

bioavailable and toxic state, would be conservatively used to represent toxicity at higher more 

alkaline conditions under which the ionized form would dominate.

Table 26 - Acute Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature 

Species % Purity

Test Type/ 

Temp/ 

pH/ 

Hardness 

or 

Salinityb

Endpoint

(ug ai/L)a

Toxicity 

Category

Study Classification/

Source/

Comments

FRESHWATER

Fathead minnow

(Pimephales 

promelas), 0.04 

g, 15 mm

Triclosan

99.7%

S, U/ 22 

o

C/ 7.5 / 

46

96-h LC50 = 260

96-h NOAEC = 100

Highly 

toxic

Supplemental

Bowman, 1990, 1994

MRID 43046001 and 

43295601/

Triclosan concentration 

were not measured

Rainbow Trout 

(Oncorhynchus 

mykiss), 0.44 g, 

34 mm

Triclosan

99.3%

S, M/ 12 

o

C/ 6.8 –

8.1/ 130 -

160

96-h LC50 = 288

96-h NOAEC = 100

Probit Slope = NA

Highly 

toxic

Supplemental/

Sword et al., 1996

MRID 43969301/

Triclosan concentrations 

were not stable 

throughout the test

Japanese 

medaka 

(Oryzias 

latipes), 2 day 

post-hatch fry

Triclosan 

pharmaceutical 

grade % 

NR

SR/

25 o

C/

NR/

NR

48-h LC50 = 352 Highly 

toxic

Unacceptable

Foran, Bennett, Benson 

2000

Control results were not 

reported, insufficient 

raw data provided to 

independently evaluate 

result, spread between 

concentrations is too 

large, solvent 

concentration not 

reported
Docket Number: EPA-HQ-OPP-2012-0811

Page 87 of 130

Species % Purity

Test Type/ 

Temp/ 

pH/ 

Hardness 

or 

Salinityb

Endpoint

(ug ai/L)a

Toxicity 

Category

Study Classification/

Source/

Comments

Japanese 

medaka 

(Oryzias 

latipes), <24-hrpost-fertilized 

embryos

Triclosan

>98.0%

SR, M/

25 o

C/

NR/

NR

96-h LC50 = 399 (nominal) Highly 

toxic

Supplemental

Ishibashi et al., 2004

Triclosan concentrations 

were not sufficiently 

stable over the renewal 

period, not clear if 

nominal or measured 

values were used but 

believe nominal, pH not 

reported, solvent 

concentration too high

Japanese 

medaka 

(Oryzias 

latipes), 24-hrold larvae

Triclosan

>98.0%

S, M/

25 o

C/

NR/

NR

96-h LC50 = 602 (nominal) Highly 

toxic

Supplemental

Ishibashi et al., 2004

Triclosan concentrations 

were not sufficiently 

stable over the renewal 

period, not clear if 

nominal or measured 

values were used but 

believe nominal, pH not 

reported, solvent 

concentration too high

Rainbow Trout 

(Oncorhynchus 

mykiss), 2 g

Triclosan

(Issue Plus 

II)

3.89%

S, U/ 17 

o

C/ 6.3 –

6.8 /NR

96-h LC50 = 910

(96-h LC50 = 23,400 f)

96-h NOAEC = 700

(96-h NOAEC = 18,000 f)

Probit Slope = 13.303

ai basis 

Highly 

toxic

Supplemental/

Terrell, 1988a MRID 

41008912/

Acceptable formulation 

test for a spray drift 

event but triclosan 

would not be expected 

to be stable under 

these exposure 

conditions

Bluegill sunfish 

(Lepomis 

macrochirus), 

2 g

Triclosan

(Issue Plus 

II)

3.89%

S, U/

22 o

C/

NR/

NR

96-h LC50 = 1,450

(96-h LC50 = 37,200 f)

96-h NOAEC = 18,000

(96-h NOAEC = 700 f)

Probit Slope = 7.794

ai basis 

Moderatel

y toxic

Supplemental/

Terrell, 1988b

MRID 41008913/

Acceptable formulation 

test for a spray drift 

event but triclosan 

would not be expected 

to be stable under these 

exposure conditions
Docket Number: EPA-HQ-OPP-2012-0811

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Species % Purity

Test Type/ 

Temp/ 

pH/ 

Hardness 

or 

Salinityb

Endpoint

(ug ai/L)a

Toxicity 

Category

Study Classification/

Source/

Comments

Zebrafish 

(Brachydanio 

rerio), 127 days 

old, 0.24 g, 

30 mm

Triclosan

(Issue Plus 

II)

3.89%

S, M/

21.4 -

24.1 o

C/

7.8 – 8.4/

NR

-- --

Unacceptable/

Bottcher, 1990

MRID 42322101

Triclosan concentrations 

not stable throughout 

study, no solvent control

Water flea 

(Daphnia 

magna), <24 h 

old

Triclosan

99.7%

S, M/

20 - 21 o

C/ 

7.9 – 8.5/

160

48-h EC50 = 390

48-h NOAEC = 100

Highly 

toxic

Supplemental/

Forbis and Muckeman, 

1990 MRID 43046002/

Nominal concentrations, 

triclosan measured but 

results highly erratic, 

shown not to be stable in 

some studies, at study 

pH conditions > half 

would be in an ionized 

form versus the more 

bioavailable nonionized 

state

Water flea 

(Daphnia 

magna), <24 h 

old

Triclosan

>99.0%

S, M/

19.5 –

22.4 o

C/

8.2 – 8.9/

256 –

278c

48-h EC50 > 139

Supplemental

Wuthrich, 1990b MRID 

43740701/

triclosan analytical 

confirmation design was 

inadequate, stability not 

demonstrated, does not 

meet conditions for a 

limit test and does not 

result in a definitive 

EC50 value

Water flea 

(Daphnia 

magna), <24 h 

old

Triclosan

Technical

S, M/

20.0 –

20.5 o

C/

8.0 – 8.4/

NR

-- --

Unacceptable/

Wuthrich, 1990a MRID 

42322102/

Measured concentrations 

were highly erratic 

therefore actual 

exposure concentration 

unknown

Water flea 

(Daphnia 

magna), <24 h 

old

Triclosan

(Issue Plus 

II)

3.89%

S, U/

NR/

NR/

NR

48-h EC50 = 16.3

(48-h EC50 = 420 f)

48-h NOAEC = 9.34

(48-h NOAEC = 240 f)

Highly 

toxic

Supplemental/

Terrell, 1988c MRID 

41008914/

lack of pH and DO 

measurements, triclosan 

not measured
Docket Number: EPA-HQ-OPP-2012-0811

Page 89 of 130

Species % Purity

Test Type/ 

Temp/ 

pH/ 

Hardness 

or 

Salinityb

Endpoint

(ug ai/L)a

Toxicity 

Category

Study Classification/

Source/

Comments

Water flea 

(Daphia 

magna), eggcarrying adults 

of various ages 

(first offspring 

were discarded)

Pharmaceutical 

grade 

Triclosan 

% NR

SR, U/

25 o

C/

8.4/

NR

6-d LC50 > 100 ppb

6-d NOAEC > 100 ppb

(survival and length of 

adults and neonates, 

ephippium production, 

fecundity, and proportion 

of male broods produced)

Unacceptable

Flaherty and Dodson 

2005

Control results were not 

provided, triclosan was 

not measured, water not 

frequently enough given 

its instability. only 3 

concentrations were 

tested and spacing is that 

of a range-finding test 

(1, 10, and 100 ppb).

f = formulation; S = Static; SR = static renewal; SS = spiked sediment; M = measured concentration; NA = Not 

applicable; NR = not reported; U = unmeasured, nominal concentrations

a Except where noted in the table.

b Water hardness as mg/L calcium carbonate (CaCO3) for freshwater tests and salinity as parts per thousand (ppt) for 

estuarine/marine tests.

c Converted from the German degrees hardness (dH) value to U.S. units, where 1 dH = 17.8 mg/L CaCO3.

Table 27 - Acute Toxicity of Triclosan to Aquatic Animals from Open Literature Provided 

by OW 

Species Method1 Chemical 

Purity Endpoint pH Effect Conc.(μg/L)

Reference/ 

Comments

FRESHWATER

Cladoceran (<24 hr),

Ceriodaphnia dubia R, M ≥96.1% 48-h EC50 6.8-7.0 130*(120* union.)

Orvos et al. 2002/

fed

Cladoceran (<24 hr),

Ceriodaphnia dubia R, M ≥96.1% 48-h EC50 7.4-7.6 175*(140* union.)

Orvos et al. 2002/

fed

Cladoceran (<24 hr),

Ceriodaphnia dubia R, M ≥96.1% 48-h EC50 8.0-8.2 235*(130* union.)

Orvos et al. 2002

fed

Cladoceran (<24 hr),

Ceriodaphnia dubia R, M ≥96.1% 48-h EC50 8.2-8.5 410*(115* union.)

Orvos et al. 2002

fed

Cladoceran (<24 hr),

Daphnia magna R, M ≥96.1% 48-h EC50 390

Orvos et al. 2002* AD 

believes study is the 

same as MRID 

43046002

Cladoceran,

Daphnia magna S, U - 48-h EC50 260 Harada et al. 2008

Crustacean (<24 hr),

Thamnocephalus 

platyurus

96-h LC50 - 470 Kim et al. 2009

Excessive solvent

Rainbow Trout,

Oncorhynchus mykiss 96-h LC50 350 Ciba 1998**
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Species Method1 Chemical 

Purity Endpoint pH Effect Conc.(μg/L)

Reference/ 

Comments

Fathead minnow,

Pimephales promelas S, U ≥96.1% 96-h LC50 260

Orvos et al. 2002

AD believes study is the 

same submitted as MRID 

43046001

Bluegill, 

Lepomis macrochirus S, U ≥96.1% 96-h LC50 370 Orvos et al. 2002

Japanese medaka 

(adult),

Oryzias latipes

R, U 96-h LC50 1700 Nassef et al. 2009

Japanese Medaka 

(2dph),

Oryzias latipes

48-h LC50 - 352 Foran et al. 2000

Duration insufficient

Japanese Medaka 

(24hpf),

Oryzias latipes

96-h LC50 - 399 Ishibashi et al. 2004

Excessive solvent

Japanese Medaka (24 

hr),

Oryzias latipes

96-h LC50 - 602 Ishibashi et al. 2004

Excessive solvent

Japanese Medaka (24 

hr),

Oryzias latipes

96-h LC50 - 600 Kim et al. 2009

Excessive solvent

Zebrafish (embryos),

Danio rerio S,U ≥97% 96-h LC50 7.0 420 Oliveira et al. 2009

Zebrafish (adults),

Danio rerio R,U ≥97% 96-h LC50 7.0 340 Oliveira et al. 2009

Southern leopard frog 

(Gosner stage 30),

Rana sphenocephala

S,U - 96-h LC50 - 562 Palenske 2009

Southern leopard frog 

(Gosner stage 36),

Rana sphenocephala

S,U - 96-h LC50 - 476 Palenske 2009

Woodhouse’s toad 

(Gosner stage 30),

Bufo woodhousii 

woodhousii

S,U - 96-h LC50 - 152 Palenske 2009

Woodhouse’s toad 

(Gosner stage 36),

Bufo woodhousii 

woodhousii

S,U - 96-h LC50 - 433 Palenske 2009

Blanchard’s cricket 

frog

(Gosner stage 22), 

Acris crepitans 

blanchardii

S,U - 96-h LC50 - 265 Palenske 2009

Blanchard’s cricket 

frog

(Gosner stage 30), 

Acris crepitans 

blanchardii

S,U - 96-h LC50 - 367 Palenske 2009

South African clawed 

frog, Xenopus laevis S, U - 96-h EC50 820 Harada et al. 2008
Docket Number: EPA-HQ-OPP-2012-0811

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Species Method1 Chemical 

Purity Endpoint pH Effect Conc.(μg/L)

Reference/ 

Comments

South African clawed 

frog (Gosner stage 

22), Xenopus laevis

S,U - 96-h LC50 - 343 Palenske 2009

South African clawed 

frog (Gosner stage 

30), Xenopus laevis

S,U - 96-h LC50 - 259 Palenske 2009

South African clawed 

frog (Gosner stage 

36), Xenopus laevis

S,U - 96-h LC50 - 443 Palenske 2009

South African clawed 

frog (Gosner stage 

46), Xenopus laevis

S,U - 96-h LC50 - 664 Palenske 2009

SALTWATER

Brown mussel 

(embryo),Perna perna S, U - IC50

7.87-8.03

Sl=35ppt 135 Cortez et al. 2012

Brown mussel 

(sperm),

Perna perna

S, U 60 min IC50

7.87-8.03

Sl=35ppt 490

Duration insufficient

Effect measured 

fertilization inhibition 1 F = flowthrough; R = static renewal; S = static; M = measured concentrations used; U = unmeasured (nominal) concentrations 

used; Sl = salinity

* Estimated from Figure 3 found in Orvos et al. 2002.

**Reported in Palenske 2009. (i.e., total triclosan versus unionized (union) triclosan).

Table 28 - Chronic Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature 

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardness 

or Salinitya

Endpoint

(ug ai/L)a

Study Classification/

Source/

Comments

FRESHWATER

Japanese medaka 

(Oryzias latipes), 

<24 h postfertilized embryos

Triclosan

>98.0%

SR, M/

25 o

C/

NR/

NR

ELS NOAEC = 156 (nominal) 

(time-to-hatch, hatching success)

Supplemental

Ishibashi et al., 2004

Triclosan concentrations were not 

sufficiently stable over the renewal 

period; growth of surviving larvae 

was not determined-insufficient 

exposure duration for growth and 

survival endpoints in an early life 

stage guideline study, nominal 

concentrations used rather than 

measured
Docket Number: EPA-HQ-OPP-2012-0811

Page 92 of 130

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardness 

or Salinitya

Endpoint

(ug ai/L)a

Study Classification/

Source/

Comments

Japanese medaka 

(Oryzias latipes), 

mature, 300 mg, 

30 mm

Triclosan

>98.0%

SR, M/

25 o

C/

NR/

NR

21-d NOAEC = 46.3c (female F0

total length)

NOEC > 112c (F0 body weight, 

female EROD and PROD activity, 

number fecundity, fertility, F1

time-to-hatch, last 24 h F1 group 

additional 90-d survival, total 

length, body weight, sex ratio)

Significant decrease in hatching 

success at 8.3c ppb but not at 46.3c

or 112c ppb

21 d parental exposure, 90 d 

observation of hatched larvae 

collected from last 24 hr exposure 

period, embryos were removed 

after fertilization and maintained 

in control water

Supplemental

Ishibashi et al., 2004

Triclosan concentrations were not 

sufficiently stable over the renewal 

period; pH not reported, 

insufficient exposure (embryos not 

exposed)

Japanese medaka 

(Oryzias latipes), 

2 day post-hatch 

fry

Triclosan 

pharmaceutical 

grade % 

NR

SR, U/

25 o

C 14 

day 

exposure, 

27 o

C post/ 

NR/

NR

NOEC > 100 (sex ratio)

NOEC = 10 (male fin length) 

(Minimum significant difference 

(MSD) in proportion of change in 

sex ratio was not provided or 

discussed)

Supplemental

Foran, Bennett, Benson 2000

14 days exposure

28 days post-exposure

triclosan was not measured, no 

negative control was included only 

a solvent control, unknown MSD, 

insufficient exposure duration and 

endpoints for a guideline fish early 

life stage study

Water flea 

(Daphnia magna), 

<24 h old

Triclosan

>99.0%

SR, M/

19.5 – 22.4 o

C/

8.2 – 8.9/

NR

21-d NOEC < 139

Parent survival, hatch success and 

survival

Supplemental/

MRID 437407-01

Growth not measured as a chronic 

endpoint, daily temperature 

unknown, triclosan analytical 

confirmation design was 

inadequate, stability not 

demonstrated
Docket Number: EPA-HQ-OPP-2012-0811

Page 93 of 130

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardness 

or Salinitya

Endpoint

(ug ai/L)a

Study Classification/

Source/

Comments

Water flea

(Daphnia magna), 

1st instar

Pharmaceutical 

grade 

Triclosan 

% NR

SR, U/

NR/

NR

NR

Significant increase in production 

of males in first brood, 72% over 

31% in controls at 10 ppb

32-d NOEC >100 ppb survival 

and length of adults, survival of 

neonates, fecundity 

Unacceptable

Flaherty and Dodson 2005

Control results were not provided, 

triclosan was not measured, 

specific concentrations tested were 

not reported, water not refreshed 

frequently enough (renewed every 

3 days) given triclosan instability, 

raw data insufficient for 

independent verification of results. 

NOAEC not provided, doseresponse unkown. Production of 

males in control in standard life 

cycle test invalidates the study. a Water hardness as mg/L calcium carbonate (CaCO3) for freshwater tests and salinity as parts per thousand (ppt) for 

estuarine/marine tests.

b GSI: gonadosomatic index; HSI: heptosomatic index; VTG: vitellogenin

c Based on mean measured concentrations taken at 24 h prior to renewal

Table 29 - Chronic Toxicity of Triclosan to Aquatic Animals from Open Literature 

Provided by OW 

Species Test Type Chemical 

(% purity) pH

Chronic Limits 

(NOAEC-LOAEC)

(μg/L)

Reference/

Comments

FRESHWATER

Cladoceran,

Ceriodaphnia dubia LC ≥96.1% 7.0

6-12 (total)

Reproduction

(5.6-11.2 union.)

Orvos et al. 2002

Cladoceran

Ceriodaphnia dubia LC ≥96.1% 8.5

182-344

Reproduction

(51.8-97.9 union.)

Orvos et al. 2002

Cladoceran

Ceriodaphnia dubia LC ≥96.1% 7.0 50-108Survival Orvos et al. 2002

Cladoceran (<24 hr),

Ceriodaphnia dubia LC ≥96.1% 8.5 339->339Survival Orvos et al. 2002

Cladoceran,

Daphnia magna LC ≥96.1% 8.2-8.6

40-200

Reproduction

(18-88 union.)

Orvos et al. 2002

Rainbow trout,

Oncorhynchus mykiss ELS ≥96.1% 8.2

34.1-71.3

Survival

(15.1-31.6 union.)

Orvos et al. 2002

Northern leopard frog,

Rana pipiens ELS - 23-230Survival Fraker and Smith 2004
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Species Test Type Chemical 

(% purity) pH

Chronic Limits 

(NOAEC-LOAEC)

(μg/L)

Reference/

Comments

Northern leopard frog

Rana pipiens ELS - 230->230Growth Fraker and Smith 2004

North American bullfrog

Rana catesbeiana ELS ≥97% 7.7

1.2-16.6

Growth Veldhoen et al. 2006

S. African clawed frog,

Xenopus laevis 21 d 7.0-7.3 32.3->32.3Survival and growth Fort et al. 2010

ELS = early life stage; LC = full life cycle

MATC = maximum allowable toxicant concentration which is the geometric mean of the NOAEC and LOAEC

Table 30 - Toxicity of Triclosan to Sediment Benthos from Submitted Studies

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardness 

or Salinityb

Endpoint

(ug ai/L)a

Study Classification/

Source/

Comments

Chironomus 

riparius, midge, 2-

3 day old-1st 

instar larvae

Triclosan

95% 14C

99.6%

SS, S, M/

NR/

NR/

NR

28-d NOAEC > 100 mg/kgsediment

(Survival, Emergence Ratio, 

Development Rate)

Supplemental

MIRD 475866-01

Developmental study. No growth 

measurements (length/weight) made on 

the larvae, no reproduction effect 

measurements 

Estuarine/Marine Fish and Invertebrates-Triclosan

For triclosan, material preservative uses, an acute toxicity study with an estuarine/marine fish, a 

mollusk22, and a shrimp23 and a chronic test with the shrimp using the TGAI are used to establish 

the toxicity of triclosan to estuarine/marine animals. To establish a saltwater ACR, the acute 

shrimp value is divided by its chronic value. No acute or chronic toxicity data have been 

submitted for estuarine/marine fish. In a preliminary list of public literature obtained from the 

Office of Water and provided to AD (Table 26), no estuarine/marine fish or shrimp data are 

listed. There is one acute mollusk study. The study will be reviewed as part of the risk 

assessment phase of registration review. An acute mollusk and mysid (shrimp) study were held 

in reserve in the RED. A chronic test with the mysid is expected to be required for registration 

review.

In the interim, where acute data for saltwater fish and mysid were missing, values were modeled 

using Web-ICE (see Appendix E) and ECOSAR as alternative sources of data. Web-ICE v3.1 

results were considered the most reasonable and result in estimates of a 96-h LC50 of 716 ppb for 

Sheepshead minnow (Cyprinodon variegatus) and a 96-h LC50 of 152 ppb for the mysid, 

Americamysis bahia. 

 22 Embryo-larvae or shell deposition 23 Penaeidae or Mysidacea
Docket Number: EPA-HQ-OPP-2012-0811

Page 95 of 130

Benthic Invertebrates

For triclosan, material preservative uses, chronic sediment toxicity studies are used because 

triclosan and methyl-triclosan are expected to adsorb to aquatic sediments (Koc = 8417-23,380 

ml/g) and the half-life in sediment is greater than ten days. One developmental study (MRID 

47586601) but no chronic reproduction study has been submitted for triclosan. No adverse 

impacts on midge larva emergence or development rate occurred at sediment concentrations up 

to 100 mg ai/kg sediment. Chronic testing is required for three species, two freshwater species (a 

midge and an amphipod (Hyallela azteca) and an estuarine/marine amphipod). These studies 

were already required as part of the post-RED DCI (GDCI 054901-30197 Docket EPA-HQOPP-2007-0513-0066) and no sediment testing in addition to these is anticipated to be required

for registration review.

Aquatic Plants

For triclosan, material preservative uses, testing with four nonvascular species (a freshwater 

diatom24, a marine diatom25, a green algae26, and a cyanobacterium27) and one vascular species 

(duckweed) using TGAI are used to establish toxicity of triclosan to aquatic plants. ). The 

registrant submitted an acceptable duckweed (L. gibba) study and three acceptable nonvascular 

species studies (freshwater diatom, Navicula pelliculosa; marine diatom, Skeletonema costatum; 

blue-green algae, Anabaena flos-aquae) but did not submit an acceptable green algae 

(Pseudokerscheneria subcapitatum [formerly Selanastrum capricornutum]) study. However, 

acceptable green algae (Scenedesmus subspicatus) data was obtained from open literature Orvos 

et al. (2002). Collectively these studies indicate that nonvascular aquatic plants, especially green 

algae (IC50 = 0.7 μg ai/L) and cyanobacteria (IC50 = 1.2 μg ai/L) are highly susceptible to 

triclosan. Duckweed (IC50 >62.5 μg ai/L) is much less susceptible than algae. No additional 

aquatic plant data are expected to be needed for triclosan. 

Table 31 - Toxicity of Triclosan to Aquatic Plants from Submitted Studies

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardb

Endpoint

(ug ai/L)

Study Classification/

Source/

Comments

Pseudokirchneriella 

subcapitata, Green 

algae (or 

Raphidocelis 

subcapitata)

99.5 S 96-h IC50 = 3.4 ppb

NOEC = 2.5 ppb

Acceptable

MRID 444228-01

 24 Navicula pelliculosa 25 Skeletonema costatum 26 Pseudokerscheneria subcapitatum [formerly Selanastrum capricornutum] 27 Anabaena flos-aquae
Docket Number: EPA-HQ-OPP-2012-0811

Page 96 of 130

Species % Purity

Test Type/ 

Temp/ pH/ 

Hardb

Endpoint

(ug ai/L)

Study Classification/

Source/

Comments

Anabaena flosaquae, freshwater 

cyanobacteria

99.5 S 96-h IC50 = 1.2 ppb

NOEC < 0.5 ppb

Acceptable

MRID 444228-01

Navicula 

pelliculosa, 

freshwater diatom

99.5 S 96-h IC50 = 16 ppb

NOEC < 0.5 ppb

Acceptable

MRID 444228-01

Skeletonema 

costatum, Marine 

diatom

99.5 S 96-h IC50 > 66 ppb

NOEC < 12 ppb

Acceptable

MRID 444228-01

Lemna gibba, 

Duckweed 99.5 S 7-d IC50 > 62.5 ppbNOEC < 12,5 ppb

Acceptable

MRID 444228-01

Table 32 - Toxicity of Triclosan to Aquatic Plants from Open Literature Reviewed by OW

Species Purity Method 1

Study 

Duration

(days)

Effect Measured pH NOEC

(μg/L)

LOEC

(μg/L)

ICx

(μg/L) Reference

FRESHWATER

Green alga

Closterium ehrenbergii >97% S, U 4

Growth rate

(asexual 

reproduction)

7.5 250 500 Ciniglia et al.

2005

Green alga

Closterium ehrenbergii >97% S, U 4

IC50 Growth rate 

(asexual 

reproduction)

7.5 - - 620 Ciniglia et al.

2005

Green alga

Closterium ehrenbergii >97% S, U 4 Zygospore production 

(sexual reproduction) 7.5 625 937.5 Ciniglia et al.

2005

Green alga

Pseudokirchneriela 

subcapitata

≥96.1% S, U 4 IC25

(growth)

7.3-

7.7 - - 2.44 Orvos et al.

2002

Green alga

Pseudokirchneriela 

subcapitata

≥96.1% S, U 4 IC50

(growth)

7.3-

7.7 - - 4.46 Orvos et al.

2002

Green alga

Pseudokirchneriela 

subcapitata

- S, U 4 IC50

(growth) - - - 12 Harada et al.

2008

Green alga,

Pseudokirchneriella 

subcapitata

Analytical 

grade

S, U 3 IC25

(Growth) - - - 3.4 Tatarazako et 

al. 2004

Green alga

Pseudokirchneriella 

subcapitata

Analytical 

grade

S, U 3 IC50

(Reduced growth) - - - 4.7 Tatarazako et 

al. 2004

Green alga,

Pseudokirchneriella 

subcapitata

98% S, U 3

IC50

(growth) (biomass via 

optical density)

7.7-

8.7 0.53 Yang et al.

2008

Green alga,

Pseudokirchneriella 

subcapitata

98% S, U 3

Growth Inhibition

(biomass via optical 

density)

7.7-

8.7 0.20 0.40 Yang et al.

2008
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Page 97 of 130

Species Purity Method 1

Study 

Duration

(days)

Effect Measured pH NOEC

(μg/L)

LOEC

(μg/L)

ICx

(μg/L) Reference

Green alga

Pseudokirchneriela 

subcapitata

99.5% S, U 3

IC50

(growth-biomass via 

optical density)

7.0 - - 2.50 Yang et al.

2011

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 4 IC50

(growth -biomass)

7.5-

7.8 - - 0.7 Orvos et al.

2002

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 4 Growth –biomass 7.5-

7.8 0.5 1.2 Orvos et al.

2002

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 4 IC50

(growth -biomass)

7.5-

7.8 - - 1.4 Orvos et al.

2002

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 4 Growth –biomass 7.5-

7.8 0.69 1.5 Orvos et al.

2002

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 3 IC50

(growth rate)

7.5-

7.8 - - 2.8 Orvos et al.

2002

Green alga

Scenedesmus

Subspicatus

≥96.1% S, M 3 Growth rate 7.5-

7.8 0.5 1.2 Orvos et al.2002

Green alga 

Scenedesmus 

vacuolatus

99.8% S, U 1 IC50 (reproductive 

inhibition) <7.0 1.9 Franz et al.

2008

Blue-green 

algaAnabaena flosaquae

≥96.1% S, M 4 IC25

(growth) 7.5 - - 0.67 Orvos et al.

2002

Blue-green 

algaAnabaena flosaquae

≥96.1% S, M 4 IC50

(growth) 7.5 - - 0.97 Orvos et al.2002

Blue-green 

algaAnabaena flosaquae

≥96.1% S,U 4 IC50

(growth – biomass) 7.5 - - 1.6 Orvos et al.

2002

Blue-green 

algaAnabaena flosaquae

≥96.1% S,U 4 Growth – biomass) 7.5 0.81 1.6 Orvos et al.

2002

Diatom 

Navicula pelliculosa ≥96.1% S, U 4 IC25

(growth)

7.2-

7.7 - - 10.7 Orvos et al.

2002

Diatom

Navicula pelliculosa ≥96.1% S, U 4 IC50(growth)

7.2-

7.7 - - 19.1 Orvos et al.2002

Duckweed

Lemna gibba ≥96.1% S, U 7 IC25 and IC50(growth)

7.7-

8.7 - - >62.5 Orvos et al.2002

Duckweed

Lemna minor >99% S, U 7 IC50(growth) - - - 26.3 Küster et al. 2007

SALTWATER

Diatom

Skeletonema costatum ≥96.1% S, U 4 IC25 and IC50(growth)

8.2-

8.5 - - >66.0 Orvos et al.2002

1 F = flowthrough; R = static renewal; S = static; M = measured concentrations used; U = unmeasured (nominal) concentrations 

used

2 MATC = maximum allowable toxicant concentration which is the geometric mean of the NOAEC and LOAEC
Docket Number: EPA-HQ-OPP-2012-0811

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Table 33 - Other Chronic Data on the Effects of Triclosan on Aquatic Organisms from 

Open Literature Reviewed by OW

Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC

(μg/L)

Reference/ 

Comments

PLANTS

Green alga,

Selenastrum sp. - 14 d Growth 7.8 10 >10 >10 Lawrence et al. 2009Only 3 concs

Green alga,

Ulothrix sp. - 14 d Growth 7.8 10 >10 >10 Lawrence et al. 2009Only 3 concs

Green alga,

Ankistrodesmus 

falcatus

- 14 d Growth 7.8 100 >100 >100 Lawrence et al. 2009

Only 3 concs

Green alga

Closterium ehrenbergii >97% 4 days Cell size and viability 7.5 250 500 353.6 Ciniglia et al. 2005Endpoint

Green alga,

Dunaliella tertiolecta - 4 day

EC50

(Growth – cell 

density)

- - - 3.55

DeLorenzo and Fleming 

2008

Excessive solvent

Green alga,

Dunaliella tertiolecta - 4 day Growth – cell 

density - 1.6 4.9 2.8

DeLorenzo and Fleming 

2008

Excessive solvent

Green alga

Scenedesmus

Subspicatus

- 4 d ? ? 2.6 >2.6 >2.6 Ferrari et al. 2002

Details

Green alga

Scenedesmus

quadricauda

- 14 d Growth 7.8 1 10 3.16 Lawrence et al. 2009

Only 3 conce

Diatom,

Nitzchia palea 99.8% 24 hr

EC50

Photosynthesis 

inhibition 

(biofilm)

≤7.0 - - 430 Franz et al. 2008

Biofilm

Diatom,

Nitzchia palea 99.8% 24 hr

EC50

Photosynthesis 

inhibition 

(suspension)

≤7.0 - - 390 Franz et al. 2008

Suspension

Diatom,

Synedra sp. - 14 d Growth 7.8 100 >100 >100 Lawrence et al. 2009Only 3 concs

Duckweed,

Lemna minor >99% 24 hr Fluorescence inhibition EC50 1,692 Küster et al. 2007Duration

Macrophyte,

Elodea canadensis >97% 72 hr Chlorophyll-a 8.8-9.0 <3 3 <3 Heilman 2008Duration

Macrophyte,

Potamogeton 

perfoliatus

>97% 72 hr Chlorophyll-a 8.8-

9.0 300 3,000 948.7 Heilman 2008

Duration

Macrophyte,

Eclipta prostrata - 28 d

Growth –

biomass (fresh 

weight)

- 8.9 55 22.12

Stevens et al. 2009

Deionized water as dilution 

water

Macrophyte,

Sesbania herbacea - 28 d

Growth –

biomass (fresh 

weight)

- 55 396 147.58

Stevens et al. 2009

Deionized water as dilution 

water

Macrophyte,

Bidens frondosa - 28 d

Growth –

biomass (fresh 

weight)

- 396 >396 >396

Stevens et al. 2009

Deionized water as dilution 

water

INVERTEBRATES

Rotifer, 

Brachionus calyciflorus - 2 d NR - 50 >50 >50

Ferarri et al. 2002

No Endpoint

Zebra mussel (20 mm),

Dreissena polymorpha 97% 96 hr Increased 

DNA damage 7.5 <0.29 0.29 <0.29

Binelli et al. 2009a

Fed
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Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC

(μg/L)

Reference/ 

Comments

Zebra mussel (20 mm),

Dreissena polymorpha 97% 96 hr

Destabilization 

of lysosomal 

membranes

7.5 0.58 0.870 0.71

Binelli et al. 2009a

Fed

Midge (12 d),

Chironomus dilutes ≥97% 10 d EC50,Growth 8.4 - - 280 Dussault et al. 2008Excessive solvent

Midge (12 d),

Chironomus dilutes ≥97% 10 d EC50,Survival 8.4 - - 400 Dussault et al. 2008Excessive solvent

Cladoceran (<24 hr),

 Ceriodaphnia dubia

Analytical 

grade 7 days

IC25 

Reproduction 

(Fecundity)

7.0-

7.5 - - 170

Tatarazako et al. 2004

Unmeasured short-term 

chronic test

Cladoceran (<24 hr),

 Ceriodaphnia dubia

Analytical 

grade 7 days

IC50 

Reproduction

(Fecundity)

7.0-

7.5 - - 220

Tatarazako et al. 2004

Unmeasured short-term 

chronic test

Cladoceran,

 Ceriodaphnia dubia - 7 days

NR (assumed 

survival and 

reproduction)

- 4 >4 >4

Ferarri et al. 2002

No Endpoint

Cladoceran 

(adult with eggs),

 Daphnia magna

Analytical 

grade 6 days LC50 Survival 8.4 100 >100 >100

Flaherty and Dodson 2005

Duration;

Unmeasured subchronic test

Cladoceran

(adult with eggs),

 Daphnia magna

Analytical 

grade 6 days Growth

(length) 8.4 100 >100 >100

Flaherty and Dodson 2005

Duration;

Unmeasured subchronic test

Cladoceran

(adult with eggs),

 Daphnia magna

Analytical 

grade 6 days Resting egg 

production 8.4 100 >100 >100

Flaherty and Dodson 2005

Duration;

Unmeasured subchronic test

Cladoceran

(adult with eggs),

 Daphnia magna

Analytical 

grade 6 days Fecundity 8.4 100 >100 >100

Flaherty and Dodson 2005

Duration;

Unmeasured subchronic test

Cladoceran

(adult with eggs),

 Daphnia magna

Analytical 

grade 6 days

Sex ratio

(proportion of 

male broods 

produced)

8.4 100 >100 >100

Flaherty and Dodson 2005

Duration;

Unmeasured subchronic test

Cladoceran (<24 hr),

 Daphnia magna

Analytical 

grade 30 days LC50 Survival 8.4 10 >10 >10 Flaherty and Dodson 2005Unmeasured schronic test

Cladoceran (<24 hr),

 Daphnia magna

Analytical 

grade 30 days Growth(length) 8.4 10 >10 >10 Flaherty and Dodson 2005Unmeasured chronic test

Cladoceran (<24 hr),

 Daphnia magna

Analytical 

grade 30 days Resting egg production 8.4 10 >10 >10 Flaherty and Dodson 2005Unmeasured chronic test

Cladoceran (<24 hr),

 Daphnia magna

Analytical 

grade 30 days Fecundity 8.4 10 >10 >10 Flaherty and Dodson 2005Unmeasured chronic test

Cladoceran (<24 hr),

 Daphnia magna

Analytical 

grade 30 days Sex ratio 8.4 1 10 3.162 Flaherty and Dodson 2005Unmeasured chronic test

Cladoceran (<24 hr),

 Daphnia magna ≥96.1% 21 days Survival - 200 1000 447.2 Orvos et al. 2002Unmeasured chronic test

Amphipod (7-14 d), 

Hyalella azteca ≥97% 10 d LC50 7.7 - - 200 Dussault et al. 2008Excessive solvent

Amphipod (7-14 d), 

Hyalella azteca ≥97% 10 d EC50,Growth 7.7 - - 250 Dussault et al. 2008Excessive solvent

FISH

Japanese medaka 

(24hpf),

Oryzias latipes

98% 21 days Growth

(females) - 60.8 136.9 83.24 Ishibashi et al. 2004

Excessive solvent

Japanese medaka 

(24hpf),

Oryzias latipes

98% 14 days

Decreased 

hatchability of 

fertilized eggs

- - 313 313 Ishibashi et al. 2004

Excessive solvent

Japanese medaka 

(24hpf),

Oryzias latipes

98% 14 days Time to 

hatching - - 313 313 Ishibashi et al. 2004

Excessive solvent
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Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC

(μg/L)

Reference/ 

Comments

Japanese medaka 

(24hpf),

Oryzias latipes

98% 21 days Growth - 136.9 - >136.9 Ishibashi et al. 2004

Excessive solvent

Japanese medaka 

(mature),

Oryzias latipes

98% 21 days

Increased 

hepatic 

vitellogenin

- - 12.8 12.8 Ishibashi et al. 2004

Excessive solvent, endpoint

Japanese medaka (2 

dph),

Oryzias latipes

- 14 days Dorsal and 

anal fin lengths - 10 100 31.62 Foran et al. 2000

Duration

Japanese medaka (2 

dph), Oryzias latipes - 14 days

Gender 

development 

(sex ratio)

- 100 >100 >100 Foran et al. 2000

Duration

Japanese medaka 

(eggs),

Oryzias latipes

Analytical 

grade 14 dph IC25

Survival 7.0 - - 290 Tatarzako et al. 2004

Duration

Japanese medaka 

(eggs),

Oryzias latipes

Analytical 

grade 14 dph IC50

Survival 7.0 - - 400 Tatarzako et al. 2004Duration

Zebrafish (eggs),

Danio rerio

Analytical 

grade 9 dph IC25Survival 7.0 - - 160 Tatarzako et al. 2004Duration

Zebrafish (eggs),

Danio rerio

Analytical 

grade 9 dph IC50Survival 7.0 - - 220 Tatarzako et al. 2004Duration

Zebrafish,

Danio rerio - 10 dph

NR (assume 

hatchability 

and survival)

- 200 >200 >200 Ferarri et al. 2002

Duration

Zebrafish (embryos),

Danio rerio ≥97% 72 hr Decreased hatchability 7.0 300 500 387.30 Oliveira et al. 2009Duration

AMPHIBIANS

North American 

bullfrog 

(Gosner stage 31-33)

Rana catesbeiana

≥97% 96 hr

Reduced 

growth

(Weight loss)

7.7 0.13 Veldhoen et al. 2006

Fed

North American 

bullfrog

(Gosner stage 31-33)

Rana catesbeiana

≥97% 11 days

Increased 

hindlimb 

development

7.7 0.13 Veldhoen et al. 2006

Fed

North American 

bullfrog (Gosner stage 

31-33),

 Rana catesbeiana

>97% 18 days Hindlimb 

development 16.6 >16.6 >16.6 Veldhoen et al. 2006

Duration

North American 

bullfrog (Gosner stage 

31-33),

 Rana catesbeiana

>97% 11 days

Abundance of 

TRα, TRß & 

PCNA mRNA

7.7 16.6 >16.6 >16.6

Veldhoen et al. 2006

Duration;

Endpoint

Southern leopard frog

(Gosner stage 30)

Rana catesbeiana

- 96 hr Decreased 

metabolic rate - 280 561 396.33 Palenske 2009

Endpoint

Southern leopard frog

(Gosner stage 30)

Rana catesbeiana

- 96 hr Increased heart 

rate - 31 47 38.17 Palenske 2009

Endpoint, U-shaped curve

Southern leopard frog

(Gosner stage 36)

Rana catesbeiana

- 96 hr Decreased 

heart rate - 63 125 88.74 Palenske 2009

Endpoint

Northern leopard frog 

(Gosner stage 26),

 Rana pipiens

- 24 days Activity level - - 0.23 0.23

Fraker and Smith 2004

Duration;

Endpoint
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Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC

(μg/L)

Reference/ 

Comments

Northern leopard frog 

(Gosner stage 26),

 Rana pipiens

- 24 days Startle 

response - 23 230 72.73

Fraker and Smith 2004

Duration;

Endpoint

Blanchard’s cricket 

frog

(Gosner stage 22)

Acris crepitans 

blanchardii

- 96 hr Heart rate - 375 >375 >375 Palenske 2009

Endpoint

Blanchard’s cricket 

frog

(Gosner stage 30)

Acris crepitans 

blanchardii

- 96 hr Heart rate - 375 >375 >375 Palenske 2009

Endpoint

Blanchard’s cricket 

frog

(Gosner stage 30)

Acris crepitans 

blanchardii

- 96 hr Metabolic rate - 367 >367 >367 Palenske 2009

Endpoint

American toad (Gosner 

stage 26),

Bufo americanus

- 14 days Increased 

activity level 8.5 - 230 230

Smith and Burgett 2005

Endpoint, high control 

mortality (18.75%)

Woodhouse’s toad

(Gosner stage 30)

Bufo woodhousii 

woodhousii

- 96 hr Metabolic rate - 152 >152 >152 Palenske 2009

Endpoint

Woodhouse’s toad

(Gosner stage 30)

Bufo woodhousii 

woodhousii

- 96 hr Increased heart 

rate - 31 47 38.17 Palenske 2009

Endpoint

Woodhouse’s toad

(Gosner stage 36)

Bufo woodhousii 

woodhousii

- 96 hr Decreased 

heart rate - - 31 31 Palenske 2009Endpoint

South African clawed 

frog 

(Gosner stage 22),

 Xenopus laevis

- 96 hr Increased heart 

rate - - 47 47

Palenske 2009

Endpoint, U-shaped curve 

(decreased at 375)

South African clawed 

frog 

(Gosner stage 30),

 Xenopus laevis

- 96 hr Increased heart 

rate - 250 375 306.19 Palenske 2009

Endpoint

South African clawed 

frog 

(Gosner stage 36),

 Xenopus laevis

- 96 hr Decreased 

heart rate - 63 94 76.95 Palenske 2009

Endpoint, U-shaped curve

South African clawed 

frog 

(Gosner stage 36),

 Xenopus laevis

- 96 hr Increased heart 

rate - 250 375 306.19 Palenske 2009

Endpoint

South African clawed 

frog 

(Gosner stage 22),

 Xenopus laevis

- 96 hr Metabolic rate - 343 >343 >343

Palenske 2009

Endpoint, U-shaped curve 

(decreased at 375)

South African clawed 

frog 

(Gosner stage 30),

 Xenopus laevis

- 96 hr Metabolic rate - 443 >443 >443 Palenske 2009

Endpoint
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Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC

(μg/L)

Reference/ 

Comments

South African clawed 

frog 

(Gosner stage 36),

 Xenopus laevis

- 96 hr Metabolic rate - 664 >664 >664 Palenske 2009

Endpoint, U-shaped curve

South African clawed 

frog 

(Gosner stage 36),

 Xenopus laevis

- 96 hr Decreased 

metabolic rate - - 130 130 Palenske 2009

Endpoint

South African clawed 

frog 

(male, 50-60 g),

 Xenopus laevis

>98% 14 days Growth

(weight) - 200 >200 >200

Matsumura et al. 2005

Duration;

Unmeasured chronic

South African clawed 

frog 

(male, 50-60 g),

 Xenopus laevis

>98% 14 days Growth

(weight) - 200 >200 >200

Matsumura et al. 2005

Duration;

Unmeasured chronic

South African clawed 

frog,

 Xenopus laevis

- 21 days

Survival, 

growth, and 

metamorph.

7.0-

7.3 - 32.3 32.3 Fort et al. 2010details

Aquatic Organisms - Methyl Triclosan

For methyl triclosan, a potential reaction product under certain environmental conditions, there is 

a lack of ecological toxicity data. There is one aquatic plant study for methyl-triclosan and it 

shows methyl triclosan as being less toxic to algae than the parent material. One study was also 

submitted for a daphnid. However, an EC50 was not established because of the poor solubility of 

triclosan at concentrations exceeding 180 μg ai/L. No mortality or immobilization was observed 

at test concentrations less than or equal to 55 μg ai/L; one of 20 daphnids was reported to be 

immobile at the end of the 48-h test at 180 μg ai/L. No chronic data are available. No methyl 

triclosan was detected in effluent from textile manufacturing and is therefore not considered a 

concern for the uses being assessed. Monitoring demonstrated a lack of methyl triclosan formed 

in effluent from textile plants; therefore, it is not considered a transformation product of concern 

at this time and no additional data are expected to be required.

Table 34 - Acute Toxicity of Methyl Triclosan to Aquatic Organisms from Open Literature 

Provided by OW

Species % Purity

Test Type/ 

Temp/ 

pH/ Hard

Endpoint

(ug ai/L)

Toxicity 

Category

Study Classification/

Source/

Comments

Water flea 

(Daphnia 

magna), <24 h 

old

Methyl 

Triclosan

99.6%

S, U/

20 o

C/

7.8 – 7.9/

250

48-h EC50 > 180 

48-h NOAEC >180

Supplemental/

MRID 475866-03

Poor solubility, not 

measured, total not 

soluble concentration
Docket Number: EPA-HQ-OPP-2012-0811

Page 103 of 130

Scenedesmus 

subspicatus, 

freshwater green 

algae

Methyl 

Triclosan

S, M/

23 – 24 o

C/

8.0 – 8.9

72-h IC50 = 120 ppb

72-h NOAEC = 40 ppb

Supplemental/

MRID 475866-02

Several deviations with 

significant ones 

including: insufficient 

exposure duration, 

insufficient vessel 

volume, species not a 

standard test species
Docket Number: EPA-HQ-OPP-2012-0811

Page 104 of 130

APPENDIX D: Environmental Fate and 

Ecotoxicity Data for Appendices B and C

Adolfsson-Erici, M., M. Pettersson, J. Parkkonen and J. Sturve. 2002. Triclosan, a commonly 

used bactericide found in human milk and in the aquatic environment in Sweden. 

Chemosphere 46(9-10): 1485-1489.

Aranami, K. and J.W. Readman. 2007. Photolytic degradation of triclosan in freshwater and 

seawater. Chemosphere 66(6): 1052-1056.

Balmer, M.E., T. Poiger, C. Droz, K. Romanin, P.A. Bergqvist, M.D. Muller and H.R. Buser. 

2004. Occurrence of methyl triclosan, a transformation product of the bactericide triclosan, 

in fish from various lakes in Switzerland. Environ. Sci. Technol. 38(2): 390-395.

Balmer, M.E., H. Buser, M.D. Muller and T. Poiger. 2005. Occurrence of some organic UV 

filters in wastewater, in surface waters, and in fish from Swiss lakes. Environmental Sci. 

Technol. 39(4): 953-962.

Barber, L.B., S.H. Keefe, R.C. Antweiler, H.E. Taylor and R.D. Wass. 2006a. Accumulation of 

contaminants in fish from wastewater treatment wetlands. Environ. Sci. Technol. 40(2): 

603-611.

Barber, L.B., S.F. Murphy, P.L. Verplanck, M.W. Sandstrom, H.E. Taylor and E.T. Furlong. 

2006b. Chemical loading into surface water along a hydrological, biogeochemical, and land 

use gradient: A holistic watershed approach. Environ. Sci. Technol. 40(2): 475-486.

Barnes, K.K., D.W. Kolpin, M.T. Meyer, M.E. Thurman, E.T. Furlong, S.D. Zaugg and L.B. 

Barber. 2002. Water-quality data for pharmaceuticals, hormones, and other organic 

wastewater contaminants in U.S. streams, 1999-2000. U.S. Geological Survey Open-File 

Report 02-94.

Bätscher, R. 2006a. Methyl-triclosan: Acute toxicity to Daphnia magna in a 48-hour 

immobilization test. RCC Ltd. Environmental Chemistry & Pharmanalytics, Itlingen, 

Switzerland. Study Number A34931.

Bätscher, R. 2006b. Methyl-triclosan: Toxicity to Scenedesmus subspicatus in a 72-hour algal 

growth inhibition test. RCC Ltd. Environmental Chemistry & Pharmanalytics, Itlingen, 

Switzerland. Study Number A34918. 448 Priority Existing Chemical Assessment Report 

No. 30.
Docket Number: EPA-HQ-OPP-2012-0811

Page 105 of 130

Behera, S., S. Oh, and H. Park. 2010. Sorption of triclosan onto activated carbon, kaolinite and 

montmorillonite: Effects of pH, ionic strength, and humic acid. Journal of Hazardous 

Materials 179 (684-691).

Bendz, D., N.A. Paxeus, T.R. Ginn and F.J. Loge. 2005. Occurrence and fate of 

pharmaceutically active compounds in the environment, a case study: Hoeje River in 

Sweden. J. Hazard. Materials 122(3): 195-204.

Bester, K. 2005. Fate of triclosan and triclosan-methyl in sewage treatment plants and surface 

waters. Arch. Environ. Contam. Toxicol. 49(1): 9-17.

Binelli, A., D. Cogni, M. Parolini, C. Riva and A. Provini. 2009a. In vivo experiments for the 

evaluation of genotoxic and cytotoxic effects of triclosan in zebra mussel hemocytes. 

Aquat. Toxicol. 91(3): 238-244.

Binelli, A., D. Cogni, M. Parolini, C. Riva and A. Provini. 2009b. Cytotoxic and genotoxic

effects of in vitro exposure to triclosan and trimethoprim on zebra mussel (Dreissena 

polymorpha) hemocytes. Comp. Biochem. Physiol. C. 150(1): 50-56. 

Boyd, G.R., H. Reemtsma, D.A. Grimm and S. Mitra. 2003. Pharmaceuticals and personal care 

products (PPCPs) in surface and treated waters of Louisiana, USA and Ontario, Canada. 

Sci. Total Environ. 311(1-3): 135-149.

Boyd, G.R., J.M. Palmeri, S. Zhang and D.A. Grimm. 2004. Pharmaceuticals and personal care 

products (PPCPs) and endocrine disrupting chemicals (EDCs) in stormwater canals and 

Bayou St. John in New Orleans, Louisiana, USA. Sci. Total Environ. 333(1-3): 137-148.

Borgmann, U., D.T. Bennie, A.L. Ball and V. Palabrica. 2007. Effect of a mixture of seven 

pharmaceuticals on Hyalella azteca over multiple generations. Chemosphere. 66: 1278-

1283.

Brain, R.A., M.L. Hanson, K.R. Solomon and B.W. Brooks. 2008. Aquatic plants exposed to 

pharmaceuticals: Effects and risks. Rev. Environ. Contam. Toxicol. 192: 67-115.

Brun, E.M., E. Bonet, R. Puchades and A. Maquieira. 2008. Selective enzyme-linked 

immunosorbent assay for triclosan. Application to wastewater treatment plant effluents. 

Environ. Sci. Technol: 42: 1665-1672.

Buth, J.M.; M. Grandbois; P.J. Vikesland; K. McNeill; W.A. Arnold. Aquatic photochemistry of

chlorinated triclosan derivatives: potential source of poychlorodibenzo-p-dioxins. Environ. 

Toxicol. Chem. 2009, 28(12), 2555-2563. MRID 49159301
Docket Number: EPA-HQ-OPP-2012-0811

Page 106 of 130

Buth, J.M.; P.O. Steen; C. Sueper; D. Blumentritt; P.J. Vikesland; W.A. Arnold; K. McNeill. 

2010. Dioxin photoproducts of triclosan and its chlorinated derivatives in sediment cores. 

Environ. Sci. Technol. 44(12), 4545-4551. MRID 49159302

Canesi, L., C. Ciacci, L.C. Lorusso, M. Betti, G. Gallo, G. Poiana and A. Marcomini. 2007. 

Effects of triclosan on Mytilus galloprovincialis hemocyte function and digestive gland 

enzyme activities: Possible modes of action on non target organisms. Comp. Bioch. 

Physiol. Part C: 145: 464-472.

Capdevielle M., R. Van Egmond, M. Whelan, D. Versteeg, M. Hofmann-Kamensky, J. Inauen, 

V. Cunningham and D. Woltering. 2008. Consideration of exposure and species sensitivity 

of triclosan in the freshwater environment. Integ. Environ. Assess. Mgmt: 4(1): 15-23.

Carr, D.L., A.N. Morse, J.C. Zak, and T.A. Anderson. 2011. Microbially Mediated Degradation 

of Common Pharmaceuticals and Personal Care Products in Soil under Aerobic and 

Reduced Oxygen Conditions. Water Air Soil Pollut. 216:633-642. MRID 49197202

Cha, J., and A. Cupples. 2010. Triclocarban and triclosan biodegradation at field concentrations 

and the resulting leaching potentials in three agricultural soils. Chemosphere 81(494-499).

Chalew, T.E.A. and R.U. Halden. 2009. Environmental exposure of aquatic and terrestrial biota 

to triclosan and triclocarban. J. Am. Water Resour. Assoc. 45(1): 4-13.

Chen, J., K.C. Ahn, N.A. Gee, S.J. Gee, B.D. Hammock and B.L. Lasley. 2007. Antiandrogenic 

properties of parabens and other phenolic containing small molecules in personal care 

products. Toxicol. Appl. Pharm. 221: 278-284.

Christensen, K. (1994) Triclosan - Determination of Anaerobic Aquatic Biodegradation. Project 

Number: 93/12/5076. Unpublished study prepared by Springborn Laboratories Inc. 71 p. 

MRID 47261406

Christensen, K. (1994) Triclosan - Aerobic Biodegradation in Water. Project Number: 

93/4/4731. Unpublished study prepared by Springborn Laboratories Inc. 75 p. MRID 

47261407

Ciba. 1998. Irgasan DP 300/Irgacare MP. Toxicological and ecological data. Ciba official 

registrations 2521. Ciba Specialty Chemicals Inc.

Ciniglia, C., C. Cascone, R.L. Giudice, G. Pinto and A. Pollio. 2005. Application of methods for 

assessing the geno- and cytotoxicity of triclosan to C. ehrenbergii. J. Hazard. Materials. 

122: 227-232.

Coogan, M.A. and T.W. LaPoint. 2008. Snail bioaccumulation of triclocarban, triclosan, and 

methyl-triclosan in a North Texas, USA, stream affected by wastewater treatment plant 

runoff. Environ. Toxicol. Chem. 27(8): 1788-1793.
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Coogan, M.A., R.E. Edziyie, T.W. LaPoint and B.J. Venables. 2007. Algal bioaccumulation of 

triclocarban, triclosan, and methyl-triclosan in a North Texas wastewater treatment plant 

receiving stream. Chemosphere 67: 1911-1918.

Cortez, F.S., C.D.S. Pereira, A.R. Santos, A. Cesar, R.B. Choueri, G. A. Martini and 

M.B.Bohrer-Morel. 2012. Biological effects of environmentally relevant concentrations of 

the pharmaceutical Triclosan in the marine mussel Perna perna (Linnaeus, 1758). Environ. 

Pollut. 168: 145-150.

Cuderman, P. and E. Heath. 2007. Determination of UV filters and antimicrobial agents in 

environmental water samples. Anal. Bioanal. Chem. 387(4): 1343-1350.

DeLorenzo, M. E. and J. Fleming. 2008. Individual and mixture effects of selected 

pharmaceuticals and personal care products on the marine phytoplankton species

Dunaliella tertiolecta. Arch. Environ. Contam. Toxicol. 54(2): 203-210. 

DeLorenzo, M. E., J.M. Keller, C.D. Arthur, M.C. Finnegan, H.E. Harper, V.L. Winder and D.L. 

Zdankiewicz. 2008. Toxicity of the antimicrobial compound triclosan and formation of the 

metabolite methyl-triclosan in estuarine systems. Environ. Toxicol. 23(2): 224-232.

Duran-Alvarez, J.C., B. Prado-Pano, and B. Jiminez-Cisneros. 2012. Sorption and Desorption 

of Carbamazepine, Naproxen, and Triclosan in a Soil Irrigated with Raw Wastewater: 

Estimation of the Sorption Parameters by Considering the Initial Mass of the Compounds 

in the Soil. Chemosphere 88 (2012) 84-90.

Dussault, E.B., V.K. Balakrishnan, E. Sverko, K.R. Solomon and P.K. Sibley. 2008. Toxicity of 

human pharmaceuticals and personal care products to benthic invertebrates. Environ. 

Toxicol. Chem. 27(2): 425-432.

European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC). 2007. Intelligent 

testing strategies in ecotoxicology: Mode of action approach for specifically acting 

chemicals. Technical Report 102.

Fair, P. A., H.B. Lee, J. Adams, C. Darling, G. Pacepavicius, M. Alaee, G.D. Bossart, N. Henry 

and D. Muir. 2009. Occurrence of triclosan in plasma of wild Atlantic bottlenose dolphins 

(Tursiops truncatus) and in their environment. Environ. Pollut. 157(8-9): 2248-2254.

Fang, J-L., R.L. Stingley, F.A. Beland, W. Harrouk, D.L. Lumpkins, and P. Howard. 2010.

Occurrence, Efficacy, Metabolism, and Toxicity of Triclosan. Journal of Environmental 

Science and Health, Part C: Environmental Carcinogenesis and Ecotoxicology Reviews 

28(3):147-171. DOI: 10.1080/10590501.2010.504978. 

http://www.tandfonline.com/doi/pdf/10.1080/10590501.2010.504978
Docket Number: EPA-HQ-OPP-2012-0811

Page 108 of 130

Faust, M., R. Altenburger, T. Backhaus, H. Blanck, W. Boedeker, P. Gramatica, V. Hamer, M. 

Scholze, M. Vighi and L.H. Grimme. 2001. Predicting the joint toxicity of multicomponent s-triazine muxtures at low-effect concentrations of individual toxicants. Aquat. 

Toxicol. 56:13-32.

Federle, T.W., S.K. Kaiser and B.A. Nuck. 2002. Fate and effects of triclosan in activated 

sludge. Environ. Toxicol. Chem. 21(7): 1330-1337.

Ferarri, B., N. Paxeus, G. Pinto, A. Pollio, R. Andreozzi, R. Marotta, D. Vogna, G. Lyberatos 

and J. Garric. 2002. Fate and effect of triclosan in the aquatic ecosystems: Data for a risk 

assessment [poster]. In: Society of Environmental Toxicology and Chemistry Annual 

Meeting in Europe; 2002May 12-16; Vienna, Austria. Brussels (BE): SETAC Europe. 

Poster 73-04.

Flaherty C.M. and S.I. Dodson. 2005. Effects of pharmaceuticals on Daphnia survival, growth, 

and reproduction. Chemosphere. 61: 200-207.

Focazio, M.J., D.W. Kolpin, K.K. Barnes, E.T. Furlong, M.T. Meyer, S.D. Zaugg, L.B. Barber 

and M. E. Thurman. 2008. A national reconnaissance for pharmaceuticals and other 

organic wastewater contaminants in the United States—II) Untreated drinking water 

sources. Sci. Total. Environ. 402: 201-216.

Foran, C.M., E.R. Bennett and W.H. Benson. 2000. Developmental evaluation of a potential 

non-steroidal estrogen: triclosan. Mar. Environ. Res. 50: 153-156.

Fraker, S.L. and G.R. Smith. 2004. Direct and interactive effects of ecologically relevant 

concentrations of organic wastewater contaminants on Rana pipiens tadpoles. Environ. 

Toxicol. 19(3): 250-256.

Fort, D.J., R.L. Rogers, J.W. Gorsuch, L. Navarro, R. Peter and J.R. Plautz. 2010. Triclosan and 

anuran metamorphosis: No effect on thyroid-mediated metamorphosis in Xenopus laevis. 

Toxicological Sciences 113(2): 392-400.

Franz, S., R. Altenburger, H. Heilmeier and M. Schmitt-Jansen. 2008. What contributes to the 

sensitivity of microalgae to triclosan? Aquat. Toxicol. 90(2): 102-108.

Fulton, B.A., R.A. Brain, S. Usenko, J.A. Back, R.S. King and B.W. Brooks. 2009. Influence of 

nitrogen and phosphorus concentrations and ratios on Lemna gibba growth responses to 

triclosan in laboratory and stream mesocosm experiments. Environ. Toxicol. Chem. 28(12): 

2610-2621.

Giddings, J.M. 2007. Review of Proposed Plant-Based Acetochlor Class 2 Water Quality 

Standards for Minnesota. Compliance Services International.
Docket Number: EPA-HQ-OPP-2012-0811

Page 109 of 130

Glassmeyer, S.T., E.T. Furlong, D.W. Kolpin, J.D. Cahill, S.D. Zaugg, S.L. Werner, M.T. Meyer 

and D.D. Kryak. 2005. Transport of chemical and microbial compounds from known 

wastewater discharges: Potential for use as indicators of human fecal contamination. 

Environ. Sci. Tech. 39(14): 5157-5169.

Gomez, M.J., M.J. Martinez Bueno, S. Lacorte, A.R. Fernandez-Alba and A. Agueera. 2007. 

Pilot survey monitoring pharmaceuticals and related compounds in a sewage treatment 

plant located on the Mediterranean coast. Chemosphere 66(6): 993-1002.

Greyshock, A.E. and P.J. Vikesland. 2006. Triclosan reactivity in chloraminated waters. Environ. 

Sci. Tech. 40(8): 2615-2622.

Haggard, B.E., J.M. Galloway, W.R. Green and M.T. Meyer. 2006. Pharmaceuticals and other 

organic chemicals in selected North-Central and Northwestern Arkansas streams. J. 

Environ. Qual. 35(4): 1078-1087.

Halden, R.U. and D.H. Paull. 2005. Co-occurrence of triclocarban and triclosan in U.S. water 

resources. Environ. Sci. Tech. 39(6): 1420-1426.

Harada, A., K. Komori, N. Nakada, K. Kitamura and Y. Suzuki. 2008. Biological effects of 

PPCPs on aquatic lives and evaluation of river waters affected by different wastewater 

treatment levels. Wat. Sci. Tech. 58(8): 1541-1546.

Heidler J. and R.U. Halden. 2007. Mass balance assessment of triclosan removal during 

conventional sewage treatment. Chemosphere. 66: 362-369.

Heilman, K.E. 2008. Sublethal effects of triclosan on Potamogeton perfoliatus and Elodea 

canadensis. M.S. Thesis, Hood College, Frederick, MD. 57 p. 

Hua, W., E.R. Bennett and R.J. Letcher. 2005. Triclosan in waste and surface waters from the 

upper Detroit River by liquid chromatography-electrospray-tandem quadrupole mass 

spectrometry. Environ. Int. 31: 621-630.

Ishibashi, H., N. Matsumura, M. Hirano, M. Matsuoka, H. Shiratsuchi, Y. Ishibashi, Y. Takao 

and K. Arizono. 2004. Effects of triclosan on the early life stages and reproduction of 

medaka Oryzias latipes and induction of hepatic vitellogenin. Aquat. Toxicol. 67: 167-179.

Kasprzyk-Hordern, B., R.M. Dinsdale and A.J. Guwy. 2009. The removal of pharmaceuticals, 

personal care products, endocrine disruptors and illicit drugs during wastewater treatment 

and its impact on the quality of receiving waters. Water Res. 43: 363-380.

Kim, J.W., H. Ishibashi, R. Yamauchi, N. Ichikawa, Y. Takao, M. Hirano, M. Koga and K. 

Arizono. 2009. Acute toxicity of pharmaceutical and personal care products on freshwater 
Docket Number: EPA-HQ-OPP-2012-0811

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crustacean (Thamnocephalus platyurus) and fish (Oryzias latipes). J. Toxicol. Sci. 34(2): 

227-32. 

Kline, 2005. Specialty Biocides North America 200-2005, Volume II: United States, Kline and 

Company, Inc. 

Kobayashi, N., S. Masunaga and J. Nakanishi. 2003. Source identification and behavior of 

PCDD/Fs and dioxin-like PCBs in Japanese river water. J. Jap. Soc. Wat. Environ. 26(1): 

655-662.

Kolpin, D.W., E.T. Furlong, M.T. Meyer, E.M. Thurman, S.D. Zaugg, L.B. Barber and H.T. 

Buxton. 2002. Pharmaceuticals, hormones, and other organic wastewater contaminants in 

U.S. streams, 1999-2000: A national reconnaissance. Environ. Sci. Tech. 36(6): 1202-1211.

Kolpin, D.W., M. Skopec, M.T. Meyer, E.T. Furlong and S.D. Zaugg. 2004. Urban contribution 

of pharmaceuticals and other organic wastewater contaminants to streams during differing 

flow conditions. Sci. Total Environ. 328(1-3): 119-130.

Küster A., K. Pohl and R. Altenburger. 2007. A fluorescence-based bioassay for aquatic 

macrophytes and its suitability for effect analysis on non-photosystem II inhibitors 

Environ. Sci. Pollut. Res. 14(6): 377-383.

Latch, D.E., J.L. Packer, B.L. Stender, J. VanOverbeke, W.A. Arnold and K. McNeill. 2005. 

Aqueous photochemistry of triclosan: formation of 2,4-dichlorophenol, 2,8-

dichlorodibenzo-p-dioxin, and oligomerization products. Environ. Toxicol. Chem. 24(3): 

517-525.

Lawrence, J.R., B. Zhu, G.D. Swerhone, J. Roy, L.I. Wassenaar, E. Topp and D.R. Korber. 2009. 

Comparative microscale analysis of the effects of triclosan and triclocarban on the structure 

and function of river biofilm communities. Sci. Total Environ. 407(10): 3307-16. 

Lee, H.B., K. Sarafin, T.E. Peart, and M.L. Svoboda. 2003. Acidic Pharmaceuticals in 

Sewage—Methodology, Stability Test, Occurrence, and Removal from Ontario Samples. 

Water Qual. Res. J., Canada (38(4): 667-682.

Lee, C.J. and T.J. Rasmussen. 2006. Occurrence of organic wastewater compounds in effluentdominated streams in Northeastern Kansas. Sci. Total Environ. 371(1-3): 258-269.

Leiker, T.J., S.R. Abney, S.L. Goodbred and M.R. Rosen. 2009. Identification of methyl 

triclosan and halogenated analogues in male common carp (Cyprinus carpio) from Las 

Vegas Bay and semipermeable membrane devices from Las Vegas Wash, Nevada. Sci. 

Total Environ. 407(6): 2102-14.

Lindstrom, A., I.J. Buerge, T. Poiger, P.-A. Bergqvist, M.D. Muller and H.-R. Buser. 2002. 
Docket Number: EPA-HQ-OPP-2012-0811

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Occurrence and environmental behavior of the bactericide triclosan and its methyl 

derivative in surface waters and in wastewater. Environ. Sci. Tech. 36(11): 2322-2329.

Loraine G.A. and M.E. Pettigrove. 2006. Seasonal variations in concentrations of 

pharmaceuticals and personal care products in drinking water and reclaimed wastewater in 

southern California. Environ. Sci. Technol. 40: 687-695.

Loos, R., J. Wollgast, T. Huber and G. Hanke. 2007. Polar herbicides, pharmaceutical products, 

perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and nonylphenol and its 

carboxylates and ethoxylates in surface and tap waters around Lake Maggiore in Northern 

Italy. Anal. Bioanal. Chem. 387(4): 1469-1478.

Lyndall, J., P. Fuchsman, M. Bock, T. Barber, D. Lauren, K. Leigh, E. Perruchon and M. 

Capdevielle. 2010. Probabilistic risk evaluation for triclosan in surface water, sediment, 

and aquatic biota tissues. Integ. Environ. Assess. Manag. doi:10.1897/ieam_2009-072.1.

Matsumara, N., H. Ishibashi, M. Hirano, Y. Nagao, N. Watanabe, H. Shiratsuchi, T. Kai, T. 

Nishimura, A. Kashiwagi and K. Ariizano. 2005. Effects of nonylphenol and triclosan on 

production of plasma vitellogenin and testosterone in male South African clawed frogs. 

Bio. Pharm. Bull. 28(9): 1748-1751.

Mayer, F.L. and M.R. Ellersieck. 1986. Manual of acute toxicity: Interpretation and data base 

for 410 chemicals and 66 species of freshwater animals. Resour. Publ. No. 160, U.S. Dep. 

Interior, Fish Wildl. Serv., Washington, DC. 505 p.

McAvoy, D.C., B. Schatowitz, M. Jacob, A. Hauk and W.S. Eckhoff. 2002. Measurement of 

triclosan in wastewater treatment systems. Environ. Toxicol. Chem. 21:1323-1329. 

McDonnell, G.E. 2007. Antisepsis, disinfection, and sterilization: Types, action, and resistance. 

American Society for Microbiology Press, Washington, D.C.

McLeod, R., S.P. Muench, J.B. Rafferty, D.E. Kyle, E.J. Mui, M.J. Kirisits, D.G. Mack, C.W. 

Roberts, B.U. Samuel, R.E. Lyons, M. Dorris, W.K. Milhous and D.W. Rice. 2001. 

Ticlosan inhibits the growth of Plasmodium falciparum and Toxoplasma gondii by 

inhibition of Apicomplexan Fab I. Int. J. Parasitol. 31: 109-113.

Memmert, U. 2006. Triclosan: Effects of the development of sediment-dwelling larvae of 

Chironomus riparius in a water-sediment system with spiked sediment. RCC Ltd., Itingen, 

Switzerland, Study No. A34896.

Minnesota Pollution Control Agency (MPCA). 2006. Outline of Basis for Draft Proposed 

Acetochlor and Metolachlor Class 2 Water Quality Standards. Available at: 

http://www.pca.state.mn.us/water/standards/rulechange08.html.
Docket Number: EPA-HQ-OPP-2012-0811

Page 112 of 130

Miyazaki, T., T. Yamagishi and M. Matsumoto. 1984. Residues of 4-chloro-1-(2,4-

dichlorophenoxy)-2-methoxybenzene (triclosan methyl) in Aquatic Biota. Bull. Environ. 

Contam. Toxicol. 32(2): 227-232.

Miyoshi, N., T. Kawano, M. Tanaka, T. Kadano, T. Kosaka, M. Kunimoto, T. Takahashi and H. 

Hosoya. 2003. Use of paramecium species in bioassays for environmental risk 

management: Determination of IC50 values for water pollutants. J. Health Sci. 49(6): 429-

435.

Moldovan, Z. 2006. Occurrences of pharmaceutical and personal care products as 

micropollutants in rivers from Romania. Chemosphere 64(11): 1808-1817.

Moldovan, Z., G. Schmutzer, F. Tusa, R. Calin and A.C. Alder. 2007. An overview of 

pharmaceuticals and personal care products contamination along the River Somes 

watershed, Romania. J. Environ. Monit. 9(9): 986-993.

Morrall, D., D. McAvoy, B. Schatowitz, J. Inauen, M. Jacob, A. Hauk and W. Eckhoff. 2004. A 

field study of triclosan loss rates in river water (Cibolo Creek, TX). Chemosphere 54(5): 

653-660.

Nakada, N., H. Shinohara, A. Murata, K. Kiri, S. Managaki, N. Sato and H. Takada. 2007. 

Removal of selected pharmaceuticals and personal care products (PPCPs) and endocrinedisrupting chemicals (EDCs) during sand filtration and ozonation at a municipal sewage 

treatment plant. Water Research 41: 4373-4382.

Nakada, N., K. Kiri, H. Shinohara, A. Harada, K. Kuroda, S. Takizawa and H. Takada. 2008. 

Evaluation of pharmaceuticals and personal care products as water-soluble molecular 

markers of sewage. Environ. Sci. Technol. 42: 6347-6353.

Nassef, M, S. Matsumoto, M. Seki, I.K. Kang, J. Moroishi, Y. Shimasaki and Y. Oshima. 2009. 

Pharmaceuticals and personal care products toxicity to Japanese medaka fish (Oryzias 

latipes). J. Fac. Agric. Kyushu Univ. 54(2): 407-411.

Okumura, T. and Y. Nishikawa. 1996. Gas chromatography-mass spectrometry determination of 

triclosan in water, sediment and fish samples via methylation with diazomethane. Anal. 

Chimica Acta. 325(3): 175-184. 

Oliveira, R., I. Domingues, C.K. Grisolia, A.M.V.M. Soares. 2009. Effects of triclosan on 

zebrafish early-life stages and adults. Environ. Sci. Pollut. Res. 16: 679-688.

Orvos D.R., D.J. Versteeg, J. Inauen, M. Capdevielle, A. Rothenstein and V. Cunningham. 2002. 

Aquatic toxicity of triclosan. Environ. Toxicol. Chem. 21(7): 1338-1349.
Docket Number: EPA-HQ-OPP-2012-0811

Page 113 of 130

OW/ORD Emerging Contaminants Workgroup. 2008a. Aquatic life criteria for contaminants of 

emerging concern. Part I. General challenges and recommendations. White Paper. June 3, 

2008.

OW/ORD Emerging Contaminants Workgroup. 2008b. Aquatic life criteria for contaminants of 

emerging concern. Part II. Illustration of recommendations using data for 17αethynylestradiol (EE2). White Paper. June 3, 2008.

Palenske, N.M. 2009. Effects of triclosan, triclocarban, and caffeine exposure on the 

development of amphibian larvae. Ph.D. thesis. University of North Texas, Denton, TX. 

Parrott, J.L. and D.T. Bennie. 2009. Life-cycle exposure of fathead minnows to a mixture of six 

common pharmaceuticals and triclosan. J. Toxicol. Environ. Health A. 72(10): 633-41.

Paxeus, N. 2004. Removal of selected non-steroidal anti-inflammatory drugs (nsaids), 

gemfibrozil, carbamazepine, [beta]-blockers, trimethoprim and triclosan in conventional 

wastewater treatment plants in five EU countries and their discharge to the aquatic 

environment. Wat. Sci. Technol. 50(5): 253-260. 

Pedersen, J.A., M. Soliman and I.H. Suffet. 2005. Human pharmaceuticals, hormones, and 

personal care product ingredients in runoff from agricultural fields irrigated with treated 

wastewater. J. Agri. Food Chem. 53(5): 1625-1632.

Peng, X., Y. Yu, C. Tang, J. Tan, Q. Huang and Z. Wang. 2008. Occurrence of steroid estrogens, 

endocrine-disrupting phenols and acid pharmaceutical residues in urban riverine water of 

the Pearl River Delta, South China. Sci. Total Environ. 397: 158-166.

Price, O.R., R.J. Williams, R. van Egmond, M.J. Wilkinson, and M.J. Whelan. 2010. Predicting 

accurate and ecologically relevant regional scale concentrations of triclosan in rivers for 

use in higher-tier aquatic risk assessments. Environment International 36 (2010) 521–526.

Quinlan, E., C. Nietch, A. Batt, K. Blocksom, D. Klemm, J. Lazorchak. 2010. Stream periphyton 

exposure to tetracycline and triclosan in an experimental mesocosm. Unpublished 

powerpoint presentation. U.S. EPA. Cincinnati, OH.

Reiss, R., N. Mackay, C. Habig and J. Griffin. 2002. An ecological risk assessment for triclosan 

in lotic systems following discharge from wastewater treatment plants in the United States. 

Environ. Toxicol. Chem. 21(11): 2483-2492.

Remberger, M., J. Sternbeck and K. Strömberg. 2002. Screening of triclosan and some 

brominated phenolic substances in Sweden. IVL Svenska Miljöinstitutet AB.

Sabaliunas, D., S.F. Webb, A. Hauk, M. Jacob and W.S. Eckhoff. 2003. Environmental fate of 

Triclosan in the River Aire Basin, UK. Wat. Res. 37(13): 3145-3154.
Docket Number: EPA-HQ-OPP-2012-0811

Page 114 of 130

Schneegurt M.A., D. M. Sherman and L.A. Sherman. 1997. Growth, physiology, and 

ultrastructure of a diazotrophic cyanobacterium, Cyanothece sp. strain ATTC 51142, in 

mixotrophic and chemoheterotrophic cultures. J. Phycol. 33:632-642.

Singer, H., S. Muller, C. Tixier and L. Pillonel. 2002. Triclosan: occurrence and fate of a widely 

used biocide in the aquatic environment: field measurements in wastewater treatment 

plants, surface waters, and lake sediments. Environ. Sci. Tech. 36(23): 4998-5004.

Smith, G.R. and A.A. Burgett. 2005. Effects of three organic wastewater contaminants on 

American toad, Bufo Americanus, tadpoles. Ecotoxicol. 14:477-482.

Snyder, S.A., J. Leising, P. Westerhoff, Y. Yoon, H. Mash and B. Vanderford. 2004. Biological 

and physical attenuation of endocrine disruptors and pharmaceuticals: implications for 

water reuse. Ground Wat. Monitor. Remed. 24(2): 108-118.

Spare, W.C. 1993. Aqueous photolysis of triclosan. Report 12208. Ciba Specialty Chemical, 

Basel, Switzerland.

Standley, J. R.A. Rudel, C.H. Swartz, K.R. Attfield, J. Christian, M. Erickson and J.G. Brody. 

2008. Wastewater-contaminated groundwater as a source of endogenous hormones and 

pharmaceuticals to surface water ecosystems. Environ. Toxicol. Chem 27(12): 2457-2468.

Stasinakis, A. S., A.V. Petalas, D. Mamais, N. S. Thomaidis, G. Gatidou and T. D. Lekkas. 

2007a. Investigation of triclosan fate and toxicity in continuous-flow activated sludge 

systems. Chemosphere. 68: 375-381.

Stasinakis, A. S., D. Mamais, N. S. Thomaidis, E. Danika, G. Gatidou and T. D. Lekkas. 2007b. 

Inhibitory effect of triclosan and nonylphenol on respiration rates and ammonia removal in 

activated sludge systems. Ecotoxicol. Environ. Saf. doi:10.1016/j.ecoenv.2007.12.011.

Stasinakis, A. S., G. Gatidou. D. Mamais, N.S. Thomaidis and T.D. Lekkas. 2008. Occurrence 

and fate of endocrine disrupters in Greek sewage treatment plants. Water Research. 42: 

1796-1804.

Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman and W.A. Brungs. 1985. 

Guidelines for deriving numerical national water quality criteria for the protection of 

aquatic organisms and their uses. PB85-227049. National Technical Information Service, 

Springfield, VA.

Stevens, K.J., S. Kim, S. Adhikari, V. Vadapalli and B.J. Venables. 2009. Effects of triclosan on 

seed germination and seedling development of three wetland plants: Sesbania herbacea, 

Eclipta prostrate, and Bidens frondosa. Environ. Toxicol. Chem. 28(12): 2598-2609.
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Stickler, D.J. and G.L. Jones. 2008. Reduced susceptibility of Proteus mirabilis to triclosan. 

Antimicrob. Agents Chemotherapy 52(3): 991-994.

Sullivan C., C. L. Mitchelmore, R.C. Hale and P.A. Van Veld. 2007. Induction of CYP1A and 

DNA damage in the fathead minnow (Pimephales promelas) following exposure to 

biosolids. Sci. Total Environ. 384:221-228.

Tatarazako N., H. Ishibashi, K. Teshima, K. Kishi and K Arizono. 2004. Effects of triclosan on 

various aquatic organisms. Environ. Sci. 11:133-140.

Thompson, A. and K. Goyne. 2012. Introduction to the Sorption of Chemical Constituents in 

Soils. Nature Education Knowledge 3(10):7. 

http://www.nature.com/scitable/knowledge/library/introduction-to-the-sorption-ofchemical-constituents-94841002

Tixier, C., H.P. Singer, S. Canonica and S.R. Mueller. 2002. Phototransformation of triclosan in 

surface waters: A relevant elimination process for this widely used biocide - laboratory 

studies, field measurements, and modeling. Environ. Sci. Tech. 36(16): 3482-3489.

Topp, E., S. C. Monteiro, A. Beck, B. B. Coelho, A.B.A. Boxall, P.W. Duenk, S. Kleywegt, D.R. 

Lapen, M. Payne, L. Sabourin, H. Li and C.D. Metcalfe. 2008. Runoff of pharmaceuticals and 

personal care products following application of biosolids to an agricultural field. Sci. Total 

Environ. doi:10.1016/jscitotenv.2008.02.011.

Toropov, A.A. and E. Benfenati. 2006. QSAR models for Daphnia toxicity of pesticides based 

on combinations of topological parameters of molecular structures. Bioorgan. Med. Chem. 

14(8): 2779-2788.

U.S. EPA. 1983b. Water quality standards regulation. Federal Register 48:51400. November 8.

U.S. EPA. 1986. Chapter 1-Stream design flow for steady-state modeling. In: Book VI-Design 

conditions. In: Technical guidance manual for performing waste load allocation. Office of 

Water, Washington, DC. August.

U.S. EPA. 1987. Permit writers guide to water quality-based permitting for toxic pollutants. 

EPA-440/4-87-005. Office of Water, Washington, DC.

U.S. EPA. 1991. Technical support document for water quality-based toxics control. 

EPA-505/2-90-001. Office of Water, Washington, DC, March; or PB91-127415, National 

Technical Information Service, Springfield, VA.

U.S. EPA. 1994. Water Quality Standards Handbook. 2nd Ed. EPA-823-B-94-005b. Office of 

Water, Washington, D.C.
Docket Number: EPA-HQ-OPP-2012-0811

Page 116 of 130

U.S. EPA Science Advisory Board (SAB). 2008. SAB advisory on aquatic life water quality 

criteria for contaminants of emerging concern. EPA-SAB-09-007. Ecological Processes 

and Effects Committee, Science Advisory Board, U.S. EPA. Washington, D.C. [Available 

at: 

http://yosemite.epa.gov/sab/SABPRODUCT.NSF/b5d8a1ce9b07293485257375007012b7/E37

FB6980DCDD9B585257532005F6F2C/$File/EPA-SAB-09-007-unsigned.pdf].

U.S. EPA. 1998. Guidelines for ecological risk assessment. EPA/630/R-95/002F. Federal 

Register 63(93):26846-26924.

U.S. EPA. 2010. Technical support document for the development of aquatic life criteria for 

contaminants of emerging concern. Draft.

U.S. Geological Survey. 2005. Effects of nonpoint and selected point contaminant sources on 

stream-water quality and relations to land use in Johnson County, Northeastern Kansas, 

October 2002 through June 2004. Scientific Investigations Report 2005-5144.

Valters, K., H. Li, M. Alaee, I. D'Sa, G. Marsh, A. Bergman and R.J. Letcher. 2005. 

Polybrominated diphenyl ethers and hydroxylated and methoxylated brominated and 

chlorinated analogues in the plasma of fish from the Detroit River. Environ. Sci. Tech. 

39(15): 5612-5619.

van Wezel, A.P. and T. Jager. 2002. Comparison of two screening level risk assessment 

approaches for six disinfectants and pharmaceuticals. Chemosphere 47(10): 1113-1128.

Veldhoen N., R.C. Skirrow, H. Osachoff, H. Wigmore, D.J. Clapson, M.P. Gunderson, G. Van 

Aggelen and C.C. Helbing. 2006. The bactericidal agent triclosan modulates thyroid 

hormone-associated gene expression and disrupts postembryonic anuran development. 

Aquat. Toxicol. 80:217-227.

Waltman, E.L., B.J. Venables and W.T. Waller. 2006. Triclosan in a North Texas wastewater 

treatment plant and the influent and effluent of an experimental constructed wetland. 

Environ. Toxicol. Chem. 25(2): 367-372.

Walters, E., K. McClellan, and R. Halden. 2010. Occurrence and loss over three years of 72 

pharmaceuticals and personal care products from biosolids-soil mixtures in outdoor 

mesocosms. Water Research 44 (6011-6020).

Weigel, S., U. Berger, E. Jensen, R. Kallenborn, H. Thoresen and H. Huhnerfuss. 2004. 

Determination of selected pharmaceuticals and caffeine in sewage and seawater from 

Tromso/Norway with emphasis on ibuprofen and its metabolites. Chemosphere 56(6): 583-

592.

White, K.L., B.E. Haggard, M.D. Matlock and J. Kim. 2005. Periphytic chlorophyll-a response 
Docket Number: EPA-HQ-OPP-2012-0811

Page 117 of 130

to triclosan exposure: Application of a passive diffusion periphytometer. Appl. Eng. Agric. 

21:307-311.

Wilkison, D.H., D.J. Armstrong, S.D. Zaugg and D.W. Blevins. 2000. Use of wastewater 

indicators to assess the impacts of combined sewer overflows on two urban streams. 

National Groundwater Association Emerging Issues Conference, June 7-8, 2000, 

Minneapolis, MN.

Wilson, B.A., V. H. Smith, F. DeNoyelles and C.K. Larive. 2003. Effects of three 

pharmaceutical and personal care products on natural freshwater algal assemblages. 

Environ. Sci. Technol. 37:1713-1719.

Wind, T. 2004. Prognosis of environmental concentrations by geo-referenced and generic 

models: A comparison of GREAT-ER and EUSES exposure simulations for some 

consumer-product ingredients in the Itter. Chemosphere 54(8): 1145-1153.

Wu, J.L., N.P. Lam, D. Martens, A. Kettrup and Z. Cai. 2007. Triclosan determination in water 

related to wastewater treatment. Talanta 72: 1650-1654.

Xie, Z., R. Ebinghaus, G. Floser, A. Caba and W. Ruck. 2008. Occurrence and distribution of 

triclosan in the German Bight (North Sea). Environ. Pollut. 156(3): 1190-1195.

Xu, J.; L. Wu; A.C. Chang. 2009. Degradation and adsorption of selected pharaceuticals and 

personal care products (PPCPs) in agricultural soils. Chemospere 77:1299-1305. MRID 

49159303.

Yang, L.H., G.G Ying, H.C. Su, J.L. Stauber, M.S. Adams and M.T. Binet. 2008. Growthinhibiting effects of 12 antibacterial agents and their mixtures on the freshwater microalga 

Pseudokirchneriella subcapitata. Environ. Toxicol. Chem. 27(5): 1201-1208.

Ying, G. and R.S. Kookana. 2007. Triclosan in wastewaters and biosolids from Australian 

wastewater treatment plants. Environ. Intl. 33: 199-205.

Ying, G.G., X.Y. Yu, and R.S. Kookana. 2007. Biological Degradation of Triclocarban and 

Triclosan in a Soil under Aerobic and Anaerobic Conditions and Comparison with 

Environmental Fate Modelling. Environmental Pollution 150:300-305. MRID 49197201.

Yang, B., G.G. Ying, J.L. Zhao, L.J. Zhang, Y.X. Fang and L.D. Nghiem. 2011. Oxidation of 

triclosan by ferrate: Reaction kinetics, products identification and toxicity evaluation. J. 

Haz. Mat. 186: 227-235. 

Zhang, S., Q. Zhang, S. Darisaw, O. Ehie and G. Wang. 2007. Simultaneous quantification of 

polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and 

pharmaceuticals and personal care products (PPCPs) in Mississippi river water, in New 
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Orleans, Louisiana, USA. Chemosphere 66: 1057-1069.

Zhao, J., G. Ying, L. Wang, J. Yang, X. Yang, L. Yang and X. Li. 2009. Determination of 

phenolic endocrine disrupting chemicals and acidic pharmaceuticals in surface water of the 

Pearl Rivers in South China by gas chromatography—negative chemical ionization—mass 

spectrometry. Sci. Total Environ. 407: 962-974.

Zhao, J., G. Ying, Y. Liu, F. Chen, J. Yang and L. Wang. 2010. Occurrence and risks of triclosan 

and triclocarban in the Pearl River system, South China: From source to the receiving 

environment. J. Hazard. Mater. doi:10.1016/j.jhazmat.2010.02.082.
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APPENDIX E: Web-ICE and ECOSAR 

Results

Saltwater Fish and Shrimp Predicted Values

The utility of ECOSAR v1.11 for predicting triclosan effect endpoints for saltwater fish and 

shrimp was checked by examining its success at predicting values for fresh water fish and the 

waterflea as compared to actual freshwater fish and daphnid data. In both cases ECOSAR values 

were less toxic than actual data (ECOSAR 96-h LC50 for fish = 476 ppb versus 260 ppb for 

fathead minnow; ECOSAR 48-hr EC50 for daphnid = 469 ppb versus 390 ppb (which is an 

underestimate of toxicity) for actual Daphnia magna data), so in this case the ECOSAR model 

appears to underestimate triclosan toxicity to aquatic organisms. Therefore predictions using 

Web-ICE v3.1 were examined as an alternative. 

The most sensitive fish species was the fathead minnow (MRID 430460-01). The second most 

sensitive fish species was the rainbow trout (MRID 439693-01). The utility of the Web-ICE 

model using rainbow trout for triclosan was checked by predicting the fathead minnow value 

using the rainbow trout. This species model resulted in a fathead minnow value ((95% lower 

confidence limit, mean) 514.8, 714.8) which underestimates toxicity (actual value (260 ppb)). 

Use of the fathead minnow as the surrogate species resulted in ecotoxicity values for other fish 

species that did not underestimate toxicity, therefore the fathead minnow value was used to 

predict a value for saltwater fish. 

There are only four chemical data points that Ceriodaphnia dubia (the more sensitive freshwater 

crustacean species) and Americamysis bahia have in common which means there is a high degree 

of uncertainty in estimates made using C. dubia. For the model predicting A. bahia from D. 

magna there is 135 data points. Therefore the model using D. magna to predict A. bahia

triclosan toxicity was used. 

The ECOSAR and WEB-ICE runs are provided at the end of this appendix:

ECOSAR Version 1.11 Results Page

SMILES : O(c(c(O)cc(c1)CL)c1)c(c(cc(c2)CL)CL)c2

CHEM : Phenol, 5-chloro-2-(2,4-dichlorophenoxy)-

CAS Num: 003380-34-5

ChemID1: 

MOL FOR: C12 H7 CL3 O2 

MOL WT : 289.55

Log Kow: 4.663 (EPISuite Kowwin v1.68 Estimate)

Log Kow: (User Entered)

Log Kow: 4.76 (PhysProp DB exp value - for comparison only)

Melt Pt: (User Entered for Wat Sol estimate)

Melt Pt: 54.00 (deg C, PhysProp DB exp value for Wat Sol est, 54-57.3)
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Wat Sol: 23.45 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Wat Sol: (User Entered)

Wat Sol: 10 (mg/L, PhysProp DB exp value)

--------------------------------------

Values used to Generate ECOSAR Profile

--------------------------------------

Log Kow: 4.663 (EPISuite Kowwin v1.68 Estimate)

Wat Sol: 10 (mg/L, PhysProp DB exp value)

------------------------------------------------

Available Measured Data from ECOSAR Training Set

------------------------------------------------

 No Data Available

--------------------------------------

ECOSAR v1.1 Class-specific Estimations

--------------------------------------

Phenols

 Predicted

ECOSAR Class Organism Duration End Pt mg/L (ppm)

=========================== ================== ======== ====== ==========

Phenols : Fish 96-hr LC50 0.476

Phenols : Daphnid 48-hr LC50 0.469

Phenols : Green Algae 96-hr EC50 1.665

Phenols : Fish ChV 0.071

Phenols : Daphnid ChV 0.089

Phenols : Green Algae ChV 0.756

Phenols : Fish (SW) 96-hr LC50 0.131

Phenols : Earthworm 14-day LC50 21.919 *

Phenols : Lemna gibba 7-day EC50 0.175

=========================== ================== ======== ====== ==========

Neutral Organic SAR : Fish 96-hr LC50 0.965

(Baseline Toxicity) : Daphnid 48-hr LC50 0.701

 : Green Algae 96-hr EC50 1.443

 : Fish ChV 0.126

: Daphnid ChV 0.136

: Green Algae ChV 0.653

Note: * = asterisk designates: Chemical may not be soluble enough to

 measure this predicted effect. If the effect level exceeds the

 water solubility by 10X, typically no effects at saturation (NES)

 are reported.

------------------------------

Class Specific LogKow Cut-Offs

------------------------------

If the log Kow of the chemical is greater than the endpoint specific cut-offs

presented below, then no effects at saturation are expected for those endpoints.

Phenols:

-------

Maximum LogKow: 7.0 (Fish 96-hr LC50, Daphnid LC50)

Maximum LogKow: 6.4 (Earthworm, Lemna)

Maximum LogKow: 7.0 (Green Algae EC50

Maximum LogKow: 8.0 (ChV)

Maximum LogKow: 5.0 (Fish (SW) 96-hr LC50, Mysid)

Baseline Toxicity SAR Limitations:

---------------------------------
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Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

Web-ICE 

Surrogate Species Predicted 

Species

Predicted Values Actual Value

Acute 95% C.L. df, R2

Rainbow trout (288 ppb at pH 6.8-

8.1) Fathead minnow 715 515, 992 79, 0.888 260 at pH 7.5

Fathead minnow (260 ppb at pH 7.5) Rainbow trout 141 97, 206 79, 0.826 288 at pH 6.8-8.1

Fathead minnow (260 ppb at pH 7.5) Bluegill sunfish 188 121, 293 66, 0.933 370 at pH 

Ceriodaphnia dubia (235 ppb at pH 

8.0-8.2) Daphnia magna 143 17, 1196 6, 0.897 390 at pH 7.9-8.5

df = degrees of freedom; R2 = r-squared or coefficient of determination

Surrogate Species Predicted 

Species

Predicted Values

Acute 95% C.L. df, R2

Fathead minnow (260 ppb at pH 7.5) Sheepshead 

minnow 716 257, 1997 12, 0.537

Ceriodaphnia dubia (235 ppb at pH 

8.0-8.2)

Mysidopsis 

bahia1 152 107, 216 135, 0.689

1 Name in model is former name, current nomenclature is Americamysis bahia

Calculator - Aquatic Species

Surrogate Species: Rainbow trout (Oncorhynchus mykiss)

Predicted Species: Fathead minnow (Pimephales promelas)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

288 μg/L (2.45) 714.82 μg/L (2.85)

Select Confidence Interval: Lower Limit Upper Limit

95% 514.86 μg/L 992.45 μg/L

Model Information

Intercept: 0.669768

Slope: 0.888200

Degrees of Freedom (N-2): 79

R2: 0.825954

p-value: 0.000000
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Average value of surrogate (log value): 1077.24 (3.03)

Minimum value of surrogate (log value): 0.671479 (-0.172967)

Maximum value of surrogate (log value): 9799999.99 (6.99)

Mean Square Error (MSE): 0.372276

Sum of Squares (Sxx): 176.91

Cross-validation Success (%): 82.71

Taxonomic Distance: 4

Surrogate Species: Fathead minnow (Pimephales promelas)

Predicted Species: Rainbow trout (Oncorhynchus mykiss)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

260 μg/L (2.41) 141.46 μg/L (2.15)

Select Confidence Interval: Lower Limit Upper Limit

95% 97.28 μg/L 205.72 μg/L

Model Information

Intercept: -0.095072

Slope: 0.929919

Degrees of Freedom (N-2): 79

R2: 0.825954

p-value: 0.000000

Average value of surrogate (log value): 2307.11 (3.36)

Minimum value of surrogate (log value): 1.18 (0.075366)
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Maximum value of surrogate (log value): 10599999.99 (7.02)

Mean Square Error (MSE): 0.389762

Sum of Squares (Sxx): 168.97

Cross-validation Success (%): 87.65

Taxonomic Distance: 4

Surrogate Species: Fathead minnow (Pimephales promelas)

Predicted Species: Bluegill (Lepomis macrochirus)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

260

μg/L (2.41) 188.76 μg/L (2.27)

Select Confidence Interval: Lower Limit Upper Limit

95% 121.54 μg/L 293.17 μg/L

Model Information

Intercept: 0.022235

Slope: 0.933218

Degrees of Freedom (N-2): 66

R2: 0.790938

p-value: 0.000000

Average value of surrogate (log value): 1843.51 (3.26)

Minimum value of surrogate (log value): 1.18 (0.075366)

Maximum value of surrogate (log value): 10600000.00 (7.02)

Mean Square Error (MSE): 0.475436

Sum of Squares (Sxx): 136.31

Cross-validation Success (%): 80.88

Taxonomic Distance: 4
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Calculator - Aquatic Species

Surrogate Species: Fathead minnow (Pimephales promelas)

Predicted Species: Sheepshead minnow (Cyprinodon variegatus)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

260

μg/L (2.41) 715.97 μg/L (2.85)

Select Confidence Interval: Lower 

Limit Upper Limit

95% 256.71 

μg/L 1996.82 μg/L

Model Information

Intercept: 1.62

Slope: 0.507579

Degrees of Freedom (N-2): 12

R2: 0.536675

p-value: 0.002883

Average value of surrogate (log value): 2230.26 (3.34)

Minimum value of surrogate (log value): 2.68 (0.428134)

Maximum value of surrogate (log value): 186000.00 (5.26)

Mean Square Error (MSE): 0.358983

Sum of Squares (Sxx): 19.36

Cross-validation Success (%): 78.57

Taxonomic Distance: 4
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Surrogate Species: Daphnid (Ceriodaphnia dubia)

Predicted Species: Daphnid (Daphnia magna)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

235 μg/L 

(2.37)

143.17 μg/L (2.15)

Select Confidence Interval: Lower Limit Upper Limit

95% 17.13 μg/L 1196.11 μg/L

Model Information

Intercept: 0.309565

Slope: 0.778676

Degrees of Freedom (N-2): 6

R2: 0.804347

p-value: 0.002535

Average value of surrogate (log value): 911.76 (2.95)

Minimum value of surrogate (log value): 0.150395 (-0.822764)

Maximum value of surrogate (log value): 8808000.00 (6.94)

Mean Square Error (MSE): 1.06

Sum of Squares (Sxx): 43.42

Cross-validation Success (%): 37.5

Taxonomic Distance: 2
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Surrogate Species: Daphnid (Ceriodaphnia dubia)

Predicted Species: Mysid (Americamysis bahia)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

235

μg/L (2.37) 172.48 μg/L (2.23)

Select Confidence Interval: Lower Limit Upper Limit

95% 3.70 μg/L 8031.21 μg/L

Model Information

Intercept: 0.090613

Slope: 0.905133

Degrees of Freedom (N-2): 2

R2: 0.964719

p-value: 0.017798

Average value of surrogate (log value): 905.88 (2.95)

Minimum value of surrogate (log value): 0.050000 (-1.30)

Maximum value of surrogate (log value): 8097999.99 (6.90)

Mean Square Error (MSE): 0.580494

Sum of Squares (Sxx): 38.74

Cross-validation Success (%): 0.00

Taxonomic Distance: 5
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Surrogate Species: Daphnid (Daphnia magna)

Predicted Species: Mysid (Americamysis bahia)

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

260 μg/L (2.59) 152.19 μg/L (2.18)

Select Confidence Interval: Lower Limit Upper Limit

95% 107.28 μg/L 215.89 μg/L

Model Information

Intercept: 0.087748

Slope: 0.808413

Degrees of Freedom (N-2): 135

R2: 0.688969

p-value: 0.000000

Average value of surrogate (log value): 375.54 (2.57)

Minimum value of surrogate (log value): 0.070000 (-1.15)

Maximum value of surrogate (log value): 839999.99 (5.92)

Mean Square Error (MSE): 0.822216

Sum of Squares (Sxx): 376.22

Cross-validation Success (%): 64.96

Taxonomic Distance: 5
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APPENDIX F: For Ecological AssessmentDioxins of Concern and Equivalency 

Factors

The term “dioxins” is used to represent polychlorinated dibenzo-p-dioxins (PCDDs) and 

polychlorinated dibenzofurans (PCDFs). There are 210 different congeners of dioxins (75 

PCDDs and 135 PCDFs); however, only 17 congeners are considered to be of toxicological 

concern (listed in Table 34). For these 17 congeners, evidence is sufficient to conclude that a 

common mechanism of action, involving binding of the chemicals to the aryl hydrocarbon 

receptor (AHR) as the initial step, underlies 2,3,7,8-TCDD-like toxicity elicited by these PCDDs, 

PCDFs, and Polychlorinated biphenyls (PCBs) (Van den Berg et al., 1998, 2006; Hahn, 2002). 

Another possible source of toxicity from the use of triclosan is the presence of dioxins from 

interaction with chlorinated water. Dioxin congeners that form from triclosanare 2,7-

dibenzodichloro-p-dioxin, 2,8-dichloro-p-dioxin, 1,2,8- and 2,3,7- trichlorodioxins and 1,2,3,8-

tetrachlorodioxin in natural waters. These congeners are not among the 17 (listed below) that are 

of toxicological concern for mammals, birds, and fish.

Table 35 - Dioxin Congeners of Toxicological Concern; Toxicity equivalency factors for 

mammals, birds and fish associated with each isomer are from U.S. EPA 2008b

Congener* Mammal TEF Bird TEF Fish TEF

2378-TCDF 0.1 1 0.05

12378-PeCDF 0.03 0.1 0.05

23478-PeCDF 0.3 1 0.5

123478-HxCDF 0.1 0.1 0.1

123678-HxCDF 0.1 0.1 0.1

234678-HxCDF 0.1 0.1 0.1

123789-HxCDF 0.1 0.1 0.1

1234678-HpCDF 0.01 0.01 0.01

1234789-HpCDF 0.01 0.01 0.01

OCDF 0.0003 0.0001 <0.0001

2378-TCDD 1 1 1

12378-PeCDD 1 1 1

123478-HxCDD 0.1 0.05 0.5

123678-HxCDD 0.1 0.01 0.01

123789-HxCDD 0.1 0.1 0.01

1234678-HpCDD 0.01 <0.001 0.001

OCDD 0.0003 0.001 <0.001

*Abbreviations are as follows: TCDD = tetrachlorodibenzodioxin; PeCDD = pentachlorodibenzodioxin; HxCDD = 

hexachlorodibenzodioxin; HpCDD = Heptachlorodibenzodioxin; OCDD = Octachlorodibenzodioxin; TCDF = 
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Tetrachlorodibenzofuran; PeCDF = Pentachlorodibenzofuran; HxCDF = Hexachlorodibenzofuran; HpCDF = 

Heptachlorodibenzofuran; OCDF = octachlorodibenzofuran

Research has been conducted to characterize the toxicities of PCDDs and PCDFs especially 

relative to each other, since these compounds are often present together in the environment. 

Demonstrated toxic effects of 2,3,7,8-TCDD and other similar-acting PCDD, PCDF and PCB 

congeners in fish, birds, and mammals include adverse effects on reproduction, development, 

and endocrine functions; wasting syndrome; immunotoxicity; and mortality in both laboratory 

and field settings (U.S. EPA 2008b). The EPA (U.S. EPA 2008b) and the World Health 

Organization (Van Den Berg et al. 1998 and 2006) have established toxicity equivalency factors 

(TEFs) for dioxins as they relate to mammals, to birds and to fish (Table 34). In the TEF 

approach, the toxicities of individual congeners are related to 2,3,7,8-TCDD, which is the most 

toxic congener of dioxins to animals For each PCDD and PCDF, the concentration (or mass) of 

the chemical is multiplied by its TEF. The sum of the product for each PCDD and PCDF 

represents the toxicity equivalent (TEQ) concentration relative to 2,3,7,8-TCDD (Equation 1; 

U.S. EPA 2008b). 

Equation 1. = ∑n

n TEFn TEQ Concentration *

Dioxins, and HCB are both listed under the Stockholm Convention as Persistent Organic 

Pollutants (POPs). These chemicals are persistent, bioaccumulative and subject to long range 

transport. In general, chronic toxicity endpoints for mammals and birds exposed to pesticides are 

expressed in terms of mg pesticide/kg-bw. The toxicity of 2,3,7,8-TCDD is expressed in units of 

ng/kg-bw, which indicates that this chemical is orders of magnitude more toxic than pesticides 

which are typically assessed by OPP. When using the TEQ approach, the exposure concentration 

of each dioxin congener is adjusted relative to the toxicity of 2,3,7,8-TCDD. Based on the 

dioxin congeners formed from triclosan, calculation of total TEQ is not required, as the 

congeners formed are not of toxicological concern.