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Triclosan Registration Review Team

Human Health

William Hazel 

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 

Lance Wormell 

Office of General Counsel

Philip Ross 

Andrea Medici 
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Table of Contents 

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

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

1.2 Case Overview ................................................................................................................. 8

1.3 Chemical Identification and Properties ............................................................................ 8

1.4 Use/Usage Description ................................................................................................... 10

1.4.1 Summary of Registered Uses .................................................................................. 10

1.4.2 Usage Information .................................................................................................. 12

1.5 Regulatory History ......................................................................................................... 13

1.5.1 Recent/Pending Regulatory Actions ....................................................................... 14

1.5.2 Tolerance Information ............................................................................................ 16

1.6 Incidents ......................................................................................................................... 17

1.6.1 Human Health ......................................................................................................... 17

1.6.2 Ecological ............................................................................................................... 17

2 Anticipated Data Needs ........................................................................................................ 17

3 Human Health Risk Assessment ........................................................................................... 21

3.1 Existing Toxicological Endpoints .................................................................................. 21

3.2 Dietary Exposure ............................................................................................................ 22

3.3 Occupational and Residential Exposures ....................................................................... 23

3.3.1 Occupational Handler Exposures ............................................................................ 23

3.3.2 Residential Handler Exposures ............................................................................... 23

3.3.3 Residential Post-Application Exposures ................................................................. 23

3.4 Aggregate and Cumulative Exposure ............................................................................. 24

3.4.1 Aggregate Exposures .............................................................................................. 24

3.4.2 Cumulative Exposures ............................................................................................ 25

4 Environmental Risk Assessment........................................................................................... 25

4.1 Environmental Conceptual Model Exposure Pathways ................................................. 26

4.2 Ecological Effects Assessment ....................................................................................... 28

4.2.1 Mechanism of Action .............................................................................................. 28
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4.2.2 Measures of Effect (Ecotoxicology Endpoints) ...................................................... 29

4.3 Exposure Analysis Plan .................................................................................................. 31

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates ............................................ 31

4.3.2 Textile Manufacturing Monitoring Data ................................................................. 31

4.4 Effects Analysis Plan ..................................................................................................... 33

5 Endocrine Disruptor Screening Program (EDSP) ................................................................. 34

6 Guidance for Commenters .................................................................................................... 35

6.1 Preliminary Work Plan ................................................................................................... 35

6.1.1 Trade Irritants .......................................................................................................... 35

6.1.2 Water Quality .......................................................................................................... 35

6.1.3 Environmental Justice ............................................................................................. 36

6.1.4 Structure Activity Relationships ............................................................................. 36

6.1.5 Additional Information ........................................................................................... 37

7 Next Steps ............................................................................................................................. 37

8 References ............................................................................................................................. 38

APPENDIX A: Toxicology Profile .............................................................................................. 39

APPENDIX B: Environmental Fate ............................................................................................. 54

APPENDIX C: Ecotoxicology Profile .......................................................................................... 72

APPENDIX D: Web-ICE and ECOSAR Results ....................................................................... 107

APPENDIX E: For Ecological Assessment- Dioxins of Concern and Equivalency Factors ..... 115

List of Tables 

Table 1 - Summary of Anticipated Risk Assessments and Data Needs ......................................... 7

Table 2 - Anticipated Registration Review Schedule ..................................................................... 7

Table 3 - Chemical Identification of Triclosan ............................................................................... 8

Table 4 - Physical-Chemical Properties for Triclosan .................................................................... 9

Table 5 - Triclosan Antimicrobial Use Summary ......................................................................... 10

Table 6 – Studies Anticipated as Needed for Registration Review of Triclosan .......................... 18

Table 7 –Data Needs Required by the Data Call-In for the Triclosan RED ................................ 19

Table 8 - Toxicological Endpoints Used for the Triclosan RED .................................................. 21

Table 9 - Occupational Handler Exposure Scenarios for Triclosan ............................................. 23

Table 10 - Effects Endpoints for the Ecological Risk Assessment of Triclosan .......................... 29

Table 11—Textile Facility Characteristics During the Triclosan Monitoring Studies ................. 32
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Table 12—Triclosan and Methyl Triclosan Monitoring Data from Two Textile Manufacturing 

Facilities ........................................................................................................................................ 33

Table 13 - Acute Toxicity Profile for Triclosan ........................................................................... 39

Table 14 - Non-Acute Toxicity Studies for Triclosan .................................................................. 40

Table 15 - Abiotic Degradation of Triclosan and Degradate Formation ...................................... 57

Table 16 - Metabolism of Triclosan with Formation of Degradates ............................................ 60

Table 17 - Effect of pH on the Ionization of Triclosan at 20 oC ................................................... 62

Table 18 - Leaching and Adsorption-Desorption of Triclosan to Soil and Sediment .................. 62

Table 19 - Terrestrial Field Dissipation, Surface Runoff, Leaching, and Crop Uptake ............... 63

Table 20 - Environmental Monitoring Studies for Triclosan ........................................................ 66

Table 21 – Biological Field Monitoring of Aquatic Organisms ................................................... 69

Table 22 - Textile Monitoring Facility Characteristics ................................................................. 71

Table 23 - Textile Triclosan and Methyl Triclosan Monitoring Concentrations .......................... 71

Table 24 - Toxicity of Triclosan to Birds ..................................................................................... 72

Table 25 - Acute Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature ............................................................................................................ 77

Table 26 - Acute Toxicity of Triclosan to Aquatic Animals from Open Literature Provided by 

OW ................................................................................................................................................ 80

Table 27 - Chronic Toxicity of Triclosan to Aquatic Animals from Submitted Studies and 

Reviewed Open Literature ............................................................................................................ 82

Table 28 - Chronic Toxicity of Triclosan to Aquatic Animals from Open Literature Provided by 

OW ................................................................................................................................................ 84

Table 29 - Toxicity of Triclosan to Sediment Benthos from Submitted Studies .......................... 85

Table 30 - Toxicity of Triclosan to Aquatic Plants from Submitted Studies ................................ 86

Table 31 - Toxicity of Triclosan to Aquatic Plants from Open Literature Reviewed by OW ...... 87

Table 32 - Other Chronic Data on the Effects of Triclosan on Aquatic Organisms from Open 

Literature Reviewed by OW ......................................................................................................... 88

Table 33 - Acute Toxicity of Methyl Triclosan to Aquatic Organisms from Open Literature 

Provided by OW ........................................................................................................................... 93

Table 34 - Dioxin Congeners of Toxicological Concern; Toxicity equivalency factors for 

mammals, birds and fish associated with each isomer are from U.S. EPA 2008b ..................... 115

 

List of Figures 

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

Triclosan ....................................................................................................................................... 27

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

Plastic Agricultural Film and Mulch ............................................................................................. 28

 
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1 Introduction 

This document is the Environmental Protection Agency’s (EPA or “the Agency”) Preliminary 

Work Plan (PWP) for triclosan. The PWP 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 registration review process was designed to include a public participation component to 

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

docket, to inform the public of what it knows about triclosan and what types of new data or other 

information would be helpful for the Agency to receive as it moves toward a decision on 

triclosan. The Agency encourages all interested stakeholders to review the PWP and to provide 

comments and additional information that will help the Agency’s decision-making process for 

this chemical. 

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. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop and commit to a final work plan and schedule for the 

Triclosan Case (PC Code 054901) (Case Number 2340). 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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Table 1 - Summary of Anticipated Risk Assessments and Data Needs 

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 and mollusk; 

daphnid, mysid and fish life 

cycle tests; Post-RED ecotox 

data; leaching from agricultural 

film and mulch2

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 

Phase 2: Case Development 

Issue Final Work Plan 2014-09 

Issue Data Call-In (DCI) 2015-09 

Receive Data to be Considered in Risk Assessment 2017-09 

Open 30-Day Public Comment Period for Proposed Decision 2019-03 

Close Public Comment Period 2019-04 

Phase 3: Registration Review Decision and Implementation 
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Open 60-Day Public Comment Period for Proposed Decision 2020-09 

Close Public Comment Period 2020-11 

Issue Final Decision 2020-03 

Begin Post-Decision Follow-up 2020 

Total (years) 7 

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).

1.2 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. 

1.3 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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1.4 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%.

1.4.1 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 

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 % 

Pigment Presscakes, Dispersions, Inks Incorporation 0.3-5.0 % 10466-42 

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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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 % 

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

bathtubs 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 % 

42182-1 

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 % 

Ice making equipment (water pans, piping, tubing, guards) Incorporation 0.1-0.5 % 42182-1 

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 % 42182-1 

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, Conveyor belts, Covers for counter tops, Covers for 

table tops, Cubicle curtains, Door and floor mats, Dresses, 

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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Exercise equipment, Floor coverings, Food Services wipes 

(towels), Furniture fabrics, Garment bags, Gloves (nonmedical), 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 

1.4.2 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% through 2009. 

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 
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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” 

1.5 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 1.5.1.) 

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 has decided to undertake another comprehensive review of triclosan under the 

Registration Review Program beginning in Fiscal Year 2013, ten years earlier than originally 

planned. Since 2008, OPP has engaged in several key efforts that will ensure that our review of 

triclosan is timely, scientifically sound and transparent, with appropriate public participation. 
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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. 

1.5.1 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. EPA 

intends to publish a notice in the Federal Register in the near future announcing the receipt of the 

request pursuant to FIFRA section 6(f). 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 due to non-payment. 

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: 

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) 
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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 initiated with this PWP. 

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 2012, Health Canada and Environment Canada jointly published a preliminary assessment of 

the human health effects and environmental toxicity of triclosan (available at: 

http://www.chemicalsubstanceschimiques.gc.ca/plan/approach-approche/triclosan-eng.php). 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 
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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 

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

industrial uses of triclosan (available at: 

http://www.nicnas.gov.au/Publications/CAR/PEC/PEC30/PEC_30_overview_PDF.pdf).

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 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. 

1.5.2 Tolerance Information 

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

tolerance exemptions will be revisited during registration review. 
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1.6 Incidents 

1.6.1 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. 

1.6.2 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)3

. 

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. 

 

3

 http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm 
Docket Number: EPA-HQ-OPP-2012-0811 

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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 AnticipaData Requirement

Special Study1,2

Leaching from plastic agricultural mulch TGAI 24 Environmental Fate, Ecological Plastic/polymer agricultural mulch/film 

850.10252,4

or 850.1055 Acute mollusk TGAI 12 Ecological Textile application, plastic/polym

agricultural mulch/film 

850.10352,4 Mysid acute TGAI 12 Ecological Textile application, plastic/polym

agricultural mulch/film 

850.13002,4,5 Daphnid Life Cycle study TGAI 12 Ecological Textile application, plastic/polym

agricultural mulch/film 

850.13502 Mysid life cycle TGAI 12 Ecological Textile application, plastic/polym

agricultural mulch/film 

850.15001,2,4,5 Freshwater fish full life cycle TGAI 24 Ecological Textile application, plastic/polym

agricultural mulch/film 

875.1200 Indoor Exposure, Dermal MP; EP 24 Occupational HVAC coils 875.1400 Indoor Exposure, Inhalation MP; EP 24 Occupational HVAC coils 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 effect

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). 4 Study held in reserve in the RED pending the outcome of textile and plastic manufacturing studies. 5 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-ch

in predicting a chronic value for the most acutely sensitive freshwater species. 
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Table 7 –Data Needs Required by the 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

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 preservativesaquatic 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 

835.4400 Anaerobic Aquatic Metabolism PAIRA; TGAI 24 Environmental Fate Residential and public access premises; materials preservatives

aquatic non-food industrial use 

SS-1 

Surface Water Monitoring (textile, plastic manufacturing) 

MP; PAI; TGAI 24 Ecological 

Residential and public access premises; materials preservativesaquatic non-food industrial use 

SS-2 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 875.1400 Indoor Exposure, Inhalation MP; EP 24 Occupational Materials preservatives 875.1600 

Application Exposure Monitoring Data Reporting 

ALL 24 Occupational and Residential Materials preservatives; aquatic non-food industrial use 

875.1700 Product Use Information ALL 12 All All 
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875.2300 Indoor Surface Residue Dissipation EP 24 Residential Material preservative use in plastics (toys) 875.2700 Product Use Information ALL 12 All All 875.2800 Description of Human Activity ALL 12 All All 875.2900 Data Reporting/Calculations ALL 24 Residential Material preservative use in plastics (toys) 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 oy

factor studies. 
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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

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
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Exposure

Scenario

Dose Used in Risk 

Assessment 

Uncertainty factors 

for Risk Assessment Study and Toxicological Effects

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.

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. These uses were assessed in the 2008 RED and no 

dietary risks of concern were identified. Potential secondary (or indirect) dietary exposure for 

this registration review will be included in the aggregate assessment (see 3.4.1) based on the 

National Health and Nutrition Examination Surveys (NHANES) biological monitoring data 

because these data reflect all exposures. 
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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 tricosan 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. 

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 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. 
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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 

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. 
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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. 

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 

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 aquatic plants. 

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. 
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4.1 Environmental Conceptual Model Exposure Pathways 

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. No environmental exposure from the application of triclosan to plastic is 

expected because the label prohibits use in 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. The conceptual models for uses with potential environmental exposure are 

in Figure 1 and Figure 24

. 

 

4

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

Triclosan 

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 

TreatedTextiles

Washing/Leaching
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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 

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

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

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

detected in effluent monitoring studies for textiles 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 required 

Plan to model 

from acute-tochronic ratios 

(ACRs). 

Estuarine/marine Shrimp or Acute Data required 
Docket Number: EPA-HQ-OPP-2012-0811 

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Receptor Group Surrogate 

Species Risk Scenario Toxicity Endpoint Comment 

Reference/ 

Study 

Classification 

invertebrates oyster Chronic Data required 

Estuarine/marine 

benthic 

invertebrates 

 Chronic Data not required NA 

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

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4.3 Exposure Analysis Plan 

4.3.1 Aquatic and Terrestrial Wildlife Exposure Estimates 

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

and the in-service use of agricultural mulch conceptual models will be estimated. 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 triclosan and fate in surface water5. No information on the leach rate from 

plastic agricultural mulch is available for use 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 RED, monitoring data was used to characterize risk from pesticidal uses but it was also 

recognized that the available monitoring data was not specifically designed to identify exposure 

specifically from pesticidal (e.g., material preservative) uses but was more likely to reflect FDA 

permitted 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 in the re-registration requirements for 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. Environmental 

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 

 

5 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. 
Docket Number: EPA-HQ-OPP-2012-0811 

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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 flow6

). 

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 operating 

days during study 

triclosan was used 

15 11 

Amount (lbs) of triclosan 

applied during 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 

(nutrients-60 

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 

 

6

 "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 streamflows in the 7Q10 range are general indicators of prevalent 

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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Characteristic Facility # 1 Facility # 2 Notes 

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 

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

Manufacturing Facilities 

Facility Triclosan Concentration 

(ng/L) 

Methyl 

Triclosa

n (ng/L)

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

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 (1.8-

1.9) 

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

(1) Collected from effluent channel. Facility #1: five consecutive, 24-hour composite effluent 

samples. 

(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. 

4.4 Effects Analysis Plan 

Open literature studies will be identified through EPA’s ECOTOXicology (ECOTOX) database7, 

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 

 

7

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

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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 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). 

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. Triclosan is not among the 

group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. 

Accordingly, as part of registration review, EPA will issue future EDSP orders/data call-ins, 

requiring the submission of EDSP screening assays for triclosan. For further information on the 

status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test 

guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/. 
Docket Number: EPA-HQ-OPP-2012-0811 

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6 Guidance for Commenters 

6.1 Preliminary Work Plan 

The public is invited to comment on EPA’s Preliminary Work Plan and rationale. The Agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a final work plan for the triclosan registration review case. 

6.1.1 Trade Irritants 

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and 

other stakeholders are asked to comment on any trade irritant issues resulting from lack of 

Maximum Residue Limits (MRLs) or disparities between U.S. tolerances and MRLs in key 

export markets, providing as much specificity as possible regarding the nature of the concern. 

6.1.2 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)8,9. 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)10. More information on impaired water bodies and TMDLs can be found at 

http://www.epa.gov/owow/tmdl/. The Agency invites submission of water quality data for this 

pesticide. To the extent possible, data should conform to the quality standards in Appendix A of 

the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water 

Quality Data in OPP’s Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm), in order to ensure the 

data can be used quantitatively or qualitatively in pesticide risk assessments. 

From a preliminary examination of which 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), they are not among congeners of toxicological concern (see 

Appendices B and E). 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. 

 

8

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

9

 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T#causes_303d 10http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES 
Docket Number: EPA-HQ-OPP-2012-0811 

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6.1.3 Environmental Justice 

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to triclosan compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population. 

6.1.4 Structure Activity Relationships 

EPA must rely upon information of appropriate quality and reliability for each decision made by 

the Agency. In the Office of Pesticide Programs (OPP), the evaluation process for a pesticide 

chemical traditionally begins with the applicant’s submission of a set of studies conducted with 

the specific pesticide chemical of interest. The use of the results of such testing (measured data) 

is a logical, scientifically rigorous process that identifies the physical, chemical, and 

environmental fate properties of the pesticide, as well as the dose and endpoints at which an 

adverse effect can occur in various animal species. 

Today, there is significant interest in alternative techniques, i.e., techniques other than data 

generation that could significantly inform the Agency’s decision-making process. Recently, OPP 

has made increasing use of structure activity relationship (SAR) as part of its regulatory 

decision-making process. In the SAR process, a chemical's molecular structure is compared to 

that of other chemicals for which data are available. These structural similarities are then used to 

make predictive judgments about a chemical’s physical, chemical, and biological properties. 

Thus, the chemical’s physical, chemical, and biological properties are a function of (or directly 

related to) the chemical’s molecular structure. Quantitative SAR is referred to as QSAR. To 

develop a QSAR, a selected set of measured data on a single physical, chemical, or biological 

property is used to derive a model (an equation) to predict the value of that property. 

Since SAR assessments and QSAR modeling are another set of tools that are available to Agency 

scientists, OPP has begun a process shift that envisions shifting from the current study-by-study 

approach to an approach in which the use of predicted data, generated using validated models, is 

considered along with information from open literature and studies specifically generated under 

Part 161 requirements. All relevant information would be considered as part of a weight-of-theevidence evaluation. 

At this time, EPA believes that for certain endpoints, especially physical/chemical and fate 

properties, that SAR and QSAR might be effectively utilized to fulfill these data requirements 

for many antimicrobial pesticide chemicals. When considering biological properties, at this time, 

EPA believes that SAR and QSAR can be most effectively utilized in the evaluation of 

chemicals that exhibit lower toxicity for human health and/or ecotoxicity parameters. This is 

appropriate because the risk assessment for lower toxicity chemicals can be stream-lined, i.e., a 
Docket Number: EPA-HQ-OPP-2012-0811 

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screening-level assessment procedure rather than multiple tiers of assessments with progressively 

more data requirements. 

If stakeholders believe that submission of predicted data can fulfill one of the data needs for the 

triclosan case, then the Agency invites submission of this information. The submitter would be 

expected to supply a rationale describing the utility of the information and provide 

documentation on the scientific validity of the information. The determination that the predicted 

data fulfills the data requirement would be at the sole discretion of the Agency. Pre-submission 

consultation with the Agency is encouraged. 

6.1.5 Additional Information 

Stakeholders are also specifically asked to provide available information and data that will assist 

the Agency in refining its risk assessments, including any species-specific ecological effects 

determinations. The Agency is interested in receiving the following information: 

1. Confirmation on the following label information: 

A. Sites of application 

B. Formulations 

C. Application methods and equipment 

D. Maximum application rates 

E. Frequency of application, application intervals and maximum number of 

applications 

F. Geographic limitations on use 

2. Use or potential use distribution 

3. Use history 

4. Usage/use information for non-agricultural uses (e.g., materials preservation) 

5. Typical application interval 

6. State or local use restrictions 

7. Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency 

8. Monitoring data 

7 Next Steps 

After the close of the 60-day comment period in May 2013, the Agency will review and respond 

to any comments received in a timely manner, and then issue a Final Work Plan for the Triclosan 

case. 

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

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8 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/ 

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 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 

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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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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 - NonGuideline 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 - NonGuideline 

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 

Page 42 of 116

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

Page 43 of 116

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 44 of 116

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 45 of 116

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 

Page 46 of 116

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 47 of 116

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 non-radiolabeled 

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

Page 48 of 116

Guideline Number/ 

Study Type/ 

Test Substance (% ai)

MRID Number (Year)/ 

Citation/ 

Classification/ Doses

Results

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. 

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

Page 49 of 116

Guideline Number/ 

Study Type/ 

Test Substance (% ai)

MRID Number (Year)/ 

Citation/ 

Classification/ Doses

Results

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. 

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

Page 50 of 116

Guideline Number/ 

Study Type/ 

Test Substance (% ai)

MRID Number (Year)/ 

Citation/ 

Classification/ Doses

Results

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 3

H-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 

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

Page 51 of 116

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 

triclosan doses as high as 300 mg/kg without cotreatment with EE did not alter uterine weight or 

histology. 

Effects on Thyroid 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 52 of 116

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, 

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

Page 53 of 116

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

Page 54 of 116

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 preliminary 

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 

factors11,

12. Appendix E 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 facility 1 were: 3.2 ng/L and 6.1 ng/L respectively for triclosan and methyl-triclosan. 

The average and maximum IWC for facility 2 were: 33.1 ng/L and 43.2 ng/L respectively for 

triclosan and methyltriclosan. The study was found to be acceptable. 

To eliminate unnecessary decimals in values, most concentration units in this document are 

expressed either as nanograms/liter (ng/l) for liquids, nanograms/gram (ng/g) for solids (mostly 

sludge), or pg/g for solids (dioxins in sediments). These units translate to parts-per-trillion (ppt) 

for liquid [1 x 10-10 %], parts-per-billion (ppb) for sewage sludge [1 x 10-7 %], or parts-pertrillion 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 o

C) (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) 

significantly (criteria for non-volatility is vapor pressure <10-6 mm Hg). It is expected to exist in 

 

11 http://www.epa.gov/raf/files/tefs-for-dioxin-epa-00-r-10-005-final.pdf 12 http://www.epa.gov/raf/tefframework/index.htm 
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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 oC. 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 factors13,14). 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). 

 

13 http://www.epa.gov/raf/files/tefs-for-dioxin-epa-00-r-10-005-final.pdf 14 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/ 

Study Classification/ 

Comments 

Hydrolysis 

(OPPTS 835.2120, 161-1) 

pH 4 

pH 7 

pH 9 

Stable at 50°C MRID 42027908 

Supplemental (preliminary study only), but no 

additional data expected to be required 

MRID 00046300 not reviewed because it only 

addressed theories of dioxin formation 

Aqueous photolysis 

(OPPTS 835.2240, 161-2) 

Guideline study 

41 min 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 Latch et al., 2004 

Deionized water and Suwanee River water in 

U.S. 

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) 

Sanchez-Prado et al., 2006 

Irradiated wastewater samples in Spain 

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 

Quality unknown, study not formally 

reviewed. 

Primary degradation product was 2,8-DCDD 

in fresh- and salt water. 

2,8-DCDD peaked at 20 days for both freshand salt-water (study length of 120 days). 

2,8-DCDD reached 60 and 90 % of triclosan 

in fresh- and salt-water 
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Parameter 

Half-lives 

(parent triclosan unless 

specified) 

Source/ 

Study Classification/ 

Comments 

23 hours (deionized water) 

18 hours (wastewater) 

Mezcua et al., 2004 

Quality unknown, study not formally 

reviewed. 

Photodegradation of triclosan in water and 

wastewater in Spain 

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 

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 

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 (parts-per-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 has received acceptable studies on laboratory aerobic soil metabolism (835.4100), 

anaerobic soil metabolism (835.4200), anaerobic aquatic metabolism (835.4400), and aerobic 

aquatic metabolism (835.4300). These laboratory studies provide a measure of the biotic 

degradation potential of a compound in the environment, without the bias from dissipation by 
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leaching. Triclosan was found to degrades rapidly in the presence of oxygen in the top layer of 

soil, but be stable under anaerobic conditions (lack of oxygen) and in aquatic conditions. The 

transformation product methyl triclosan (methoxy triclosan) was formed at up to 17.5 % of 

applied triclosan. The aerobic soil metabolism study (MRID 47261401) represents the top layer 

of soil under oxygenated conditions, with half-lives of parent triclosan and the transformation 

product methyl triclosan of 2.5-11 and 39-153 days, respectively. In one aerobic soil, methyl 

triclosan was stable with no apparent degradation. Under anaerobic soil conditions (top layer of 

soil after a rain), triclosan was stable (MRID 47261401). 

Under aquatic conditions (water and sediment), triclosan partitions from the water phase to the 

sediment phase. The water and total system half-lives in the aerobic aquatic metabolism study 

(MRID 47261407) were 1.2-1.4 days and 41-58 days, respectively. No significant degradates 

were formed in the study. However, there was no apparent degradation under aquatic conditions 

in absence of oxygen (MRID 47261406). 

In addition, the Agency has received supplemental studies for soil nitrification (OECD 216) and 

soil respiration (OECD 217) for triclosan. While the studies are considered to be 

supplemental information, no additional data are expected to be required. These studies indicate 

that neither soil nitrification (MRID 47261403) nor soil respiration (MRID 47261404) are 

inhibited at concentrations up to 2 ppm (mg/kg) in soil. 

Additional studies on triclosan metabolism in environmental compartments were identified in the 

public literature. There are three public literature studies cited in Table 16 but these have not 

been formally reviewed to date. These studies will be reviewed as part of the fate assessment in 

registration review and acceptable results will be use to refine half-life values for use in the risk 

assessment. All of them provide longer parent triclosan half-lives than the guideline study 

(MRID 47261401) and one study, Christensen (1994b), also provides additional formation data 

on methyl triclosan. 

 
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Table 16 - Metabolism of Triclosan with Formation of Degradates 

Parameter Half-life of Triclosan (unless 

specified) 

Source/ 

Study Classification/ 

Comments 

Aerobic Soil Metabolism 

(OPPTS 835.4100, 162-1) 

Gartenecker loam, 1.73 % OC, 

Swiss soil 

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 

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 (stable) 

153 days (methyl triclosan) 

MRID 47261401; Adam, 2007 (Guideline 

study) 

Acceptable 

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 

 35, 29, and 17 days in silt 

loam, loam, and sandy loam 

soils treated with sewage 

sludge. 

Percent degradation was 77-93 

% (average of 83 %) with up 

to 62-80 % methyl triclosan 

formation. 

14-20 % mineralized to CO2

Christensen, 1994b 

Quality unknown, study not formally 

reviewed. 

 29-83 days for loamy sand, 

sandy loam, and sandy soil 

After 100 days, 21-25, 16-43, 

and 20-45 % of triclosan 

remained 

Cha and Cupples, 2010 

Quality unknown, study not formally 

reviewed. 

No degradate analysis 

Anaerobic Soil Metabolism 

(835.4200, 162-2) 

Stable MRID 47261401, Adam, 2007 

Acceptable 

Anaerobic Aquatic Metabolism 

(OPPTS 835.4300) 

Stable MRID 47261406, Christensen, 1994a 

Acceptable 
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Parameter Half-life of Triclosan (unless 

specified) 

Source/ 

Study Classification/ 

Comments 

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 

MRID 47261407, Adam, 2006 

Acceptable 

Soil respiration and nitrification No effect of triclosan 

treatments up to 2 ppm 

MRIDs 47261403 and 47261404 

Supplemental but no additional data 

expected to be required 

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 

U.S. soils 

Quality unknown, study not formally 

reviewed. 

High treatment rate 

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 

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 
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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 two open literature leaching-adsorption-desorption studies for triclosan. 

The Agency anticipates reviewing these studies prior to 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. 

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

Parameter Value Source/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 

Quality unknown, study not formally 

reviewed. 

No degradate analysis 

Kd values of 33, 55, and 51 

ml/g 

Koc values of 5,613, 6,310, 

and 3,968 ml/g in loamy sand, 

sandy loam, and sand soils 

Cha and Cupples, 2010 

Quality unknown, study not formally 

reviewed 

No degradate analysis 

Terrestrial Field Dissipation, Leaching, Runoff, and Crop Uptake (835.6100) 

Triclosan has been commonly detected in sewage sludge across the country. As a result triclosan 

may potentially be applied to agricultural fields as a contaminant of sewage sludge land 

applications. Triclosan input from EPA registered use patterns is expected to be primarily from 
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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 contribution is expected to be from the 

personal care product uses15. The Agency is aware of 13 field dissipation studies, one guideline 

study (Christensen, 1994b) and 12 open literature studies; 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/Comments

Degradation in sewage-sludge 

amended soils (no guideline 

number) 

Half-lives of 39, 29, and 10 days, 

respectively. 

77, 79, and 93 % reduction in 

triclosan concentrations in silt loam, 

loam, and sandy loam soils

Christensen, 1994b 

62-80 % was converted to methyl 

triclosan and 14-20 % was 

mineralized 

Quality unknown, study not formally 

reviewed.

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 

Quality unknown, study not formally 

reviewed. 

Canada 

No characterization of significant 

non-extractable 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 

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 

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 

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 halflife 

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 

Quality unknown, study not formally 

reviewed. 

Australia 

Sandy soil 
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Parameter Value Source/Comments

Surface runoff from treated soil Runoff concentrations of 26 and 258 

ng/l from injected and surfaceapplied liquid sludge 

Topp et al., 2008 

Quality unknown, study not formally 

reviewed. 

Ontario, Canada 

Silt loam soil with wheat stubble 

No degradate analysis 

Leaching through soil filters 

(activated)

83-140 ng/l flow rate (average of 

140 ng/l) with 90 % removal rate 

7-30 ng/l flow rate (average of 14 

ng/l) with 39 % removal rate 

Bester and Schafer, 2009 

Quality unknown, study not formally 

reviewed. 

Kd of 160 ml/g 

Tile drainage concentrations Triclosan present in water for 9 

months 

Maximum concentration of 14,000 

ng/g in treated soil 

Maximum concentration of 230 

ng/l in tile water. 

Sewage concentrations of 240-3,680 

ng/l in 2005 and 2006 

Edwards et al., 2009a 

Edwards et al., 2009b 

Quality unknown, study not formally 

reviewed. 

Field dissipation, leaching, and crop 

uptake 

Loam, loamy sand, and sandy loam 

soils in Canada 

Soils had 0.7-1.4 % OC and pH 

values of 5.7-6.1. 

Triclosan reached 74 ng/l in tile 

drainage, but did not reach ground 

water at >2 meters of depth. 

There was no measurable crop 

uptake in wheat. 

Gottschall et al., 2012 

Quality unknown, study not formally 

reviewed. 

Leaching in sludge-treated fields (no 

guideline) 

Triclosan detected in tile drainage at 

150 ng/l from subsurface application 

Triclosan detected in tile drainage at 

3,676 ng/l from surface application 

Detections occurred immediately 

after application 

Macropore flow was primary reason 

for detections in tiles 

Lapen et al., 2008 

Ontario, Canada 

2.1 % OC, Clay loam 

Quality unknown, study not formally 

reviewed. 

No degradate analysis 

 Soil columns from Mexico 

Triclosan concentrations in liquid 

sludge of 84-1,032 ng/l 

Up to 2.2 % of applied triclosan in 

leachate (max in sandy loam soil) 

Gibson et al., 2010 

Quality unknown, study not formally 

reviewed. 

Soils in Mexico treated with sludge 

repeatedly for 10-90 years and 

cropped 

Textures ranging from sandy loam to 

clay soils 

No degradate analysis 
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Parameter Value Source/Comments

 Triclosan applied to 774-949 ug/ha 

to loamy sand, sandy clay loam, and 

clay soils in UK. 

Most triclosan present in top 10 cm 

as either parent compound or methyl 

triclosan (2-8 % triclosan and 27-42 

% methyl triclosan). 

Triclosan residues present in 10-20 

cm of depth as either parent 

compound or methyl triclosan (2.5-5 

% triclosan and 9-18 % methyl 

triclosan). 

3-6.5 % of each compound in 20-30 

cm depth 

Total recovery of 49-84 % of 

triclosan and methyl triclosan . 

Remainder mineralized or sorbed. 

Butler et al., 2012 

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 

Quality unknown, study not formally 

reviewed. 

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 sources15. Surface water and 

 

15 According to the 2004 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 (Fang et al., 2010). 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 66 of 116

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 

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 Comments References 

Surface 

Water 

0.01-2.3 ng/l 0.19 0.05 85 45 53 Various streams 

in U.S. 

Barnes et al., 2002 

Quality unknown, 

study not formally 

reviewed. 

USGS 

<3-10 ng/l NA NA NA NA NA 

Ruhr River 

Catchment in 

Germany 

Bester (2005) 

Quality unknown, 

study not formally 

reviewed. 

1.6-29 ng/l 10.9 12.4 29 21 72 

Stormwater 

canals and 

Bayou St. John 

in New Orleans 

Boyd et al, 2004 

Quality unknown, 

study not formally 

reviewed. 

60-80 ng/l 70 70 3 2 66 Denton, TX 

Coogan et al, 2007 

Quality unknown, 

study not formally 

reviewed. 

0.398-

1.02 ng/l 0.627 NA 2 2 100 

Toxicity of 

triclosan and 

formation of 

methyl triclosan 

in estuarine 

systems 

DeLorenzo et al, 

2008 

Quality unknown, 

study not formally 

reviewed 

USGS 

4.9-13.7 ng/l 7.5 NA 13.7 13.7 100 

Estuarine water 

in Charleston 

Harbor 

Fair et al, 2009 

Quality unknown, 

study not formally 

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

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Medium Range Unit Average Median No. 

Samples

No. 

Detections 

Percent 

Detection Comments References 

0.021-1 

(RL=1) ng/l 

0.89 

(includes 

ND) 

1 5 47 10.6 

49 locations 

18 states and 

Puerto Rico 

Unfiltered 

samples 

Focazio et al., 2008 

Quality unknown, 

study not formally 

reviewed 

USGS 

110-640 ng/l NA 

200 and 

110 for 

1st and 

second 

downstr

eam 

location

s 

10 for 

each 

location 

6 

 7 60-70 Downstream of 10 WWTPs 

Glassmeyer et al., 

2005 

Quality unknown, 

study not formally 

reviewed 

USGS 

2,300 

(maximum) ng/l 176 50 145 90 62 

Streams with 

minimal dilution 

Unfiltered water 

samples 

Kolpin et al, 2002 

Quality unknown, 

study not formally 

reviewed 

USGS 

10-4,010 ng/l 193 186 36 36 100 

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 

Lishman et al., 2006 

Thames River, 

Canada 

Quality unknown, 

study not formally 

reviewed. 

70-650 ng/l NA NA NA NA NA None 

Poiger et al., 2003 

and Linstrom et al., 

2002 

34-92 % removal 

Quality unknown, 

study not formally 

reviewed. 

p. 172 of Australia 

12 ng/l 12 12 3 1 33 

Stream with >90 

% treated 

wastewater 

4o

 treatment 

Vanderford and 

Snyder, 2006 

Quality unknown, 

study not formally 

reviewed. 

0.4-85 

(dry 

weight) 

ng/g N/A N/A 24 24 (>0.4 

ng/l) 100 

Sediment in 

Minnesota 

freshwater 

bodies 

58 % of samples 

downstream of 

WWTPs were 

greater than 

upstream 

Venkatesan et al., 

2010 

Quality unknown, 

study not formally 

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

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Medium Range Unit Average Median No. 

Samples

No. 

Detections 

Percent 

Detection Comments References 

1-9 

26 

ng/l 

ng/g 

3 

26 

NA 

41 

12 

12 NA 

Lower Hudson 

River Estuary 

Water 

Sediment 

Wilson et al, 2009 

Quality unknown, 

study not formally 

reviewed. 

1,130 

(maximu

m) 

ng/l NA NA 14 9 64 

Baltimore City 

and County 

watersheds 

9-60 % removal 

Young et al, 2008 

Quality unknown, 

study not formally 

reviewed. 

193 ng/l NA NA 4 1 25 

West Prong 

Litte River, East 

Tennessee 

Yu and Chu, 2009 

Quality unknown, 

study not formally 

reviewed. 

Finished 

Reclaime

d Waste 

Water 

and 

Ground 

Water 

0.021-1 

(RL=1) ng/l 

0.89 

(includes 

ND) 

1 47 5 10.6 

25 samples in 

12 states and 

Puerto Rico 

441 wells 

sampled 

Barnes et al., 2008 

Quality unknown, 

study not formally 

reviewed 

USGS 

<1.0 NA NA NA 5 3 60 

Leachate from 

landfills in GW 

in Indiana 

Buszka et al, 2009 

Quality unknown, 

study not formally 

reviewed 

USGS 

No 

detection

s 

NA NA NA 11 0 0 

Compounds in 

Karst water in 

Florida 

Katz and Griffin, 

2008 

Quality unknown, 

study not formally 

reviewed. 

280-

2,110 ng/l 1,430 NA 6 3 50 

Reclaimed 

wastewater in 

California 

Loraine and 

Pettigrove, 2006 

Quality unknown, 

study not formally 

reviewed. 

Bottom 

Sediment 

4-10 

13-14 

ng/g 

for 

tricl

osan 

10 (1998) 

4 (2008) 

13.5 

(1998-

2003) 

10 

(1998) 

4 (2008)

13.5 

(1998-

2003) 

2 2 100 

Triclosan 

Mississippi 

River sediment 

in Minnesota 

Lake Pepin 

sediment 

triclosan 

concentrations 

Buth et al., 2010 

Concentrations of 4-

chloro triclosan, 6-

chloro triclosan, and 

4,6-dichloro 

triclosan 

1-80 pg/g for 

chlorinated 

derivatives in 

Mississippi River 

(most<20) 

50-85 pg/g for 2,8-

DCDD 

Up to 4 pg/g for 

others in Lake Pepin 

Quality unknown, 

study not formally 

reviewed. 
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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; the Agency required these 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 21 will be reviewed to gain any additional information that 

may be used for risk characterization. 

Table 21 – Biological Field Monitoring of Aquatic Organisms 

Parameter Value Source/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 

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 

Netherlands 

Quality unknown, study not formally reviewed. 

No degradates analyzed 

0.12-0.27 ng/g (mean of 0.18 ng/g) with 31 

% detection frequency at Charleston 

0.025-0.11 ng/g (mean of 0.072) with 23 % 

detection in Florida. 

Influent and effluent concentrations of 

2,800-3,400 and 190 ng/l at Charleston, SC. 

Charleston estuarine concentrations were 

4.9-14 ng/l (7.5 ng/l average)

Fair et al., 2009 

Bottlenose dolphins (Tursiops 

truncatus) 

United States 

Quality unknown, study not formally reviewed. 

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 

United States 

USGS 

Quality unknown, study not formally reviewed. 

Methyl triclosan 

BCF value of 1.7X 

30-day concentration of 461 ng/g dry 

weight of triclosan in 300 ng/l in 

Mediterranean mussel (Mytilus 

galloprovincialis) 

Depuration half-life of 12 days—slower 

than uptake rates 

Gatidou et al., 2010 

Mediterranean mussel (Mytilus 

galloprovincialis) 

Quality unknown, study not formally reviewed. 

Greece 
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Parameter Value Source/Comments 

Bioconcentration 

in snails and algae 

(no guideline) 

Triclosan concentrations of 112, 59,000, 

and 162,000 pptr 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 

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 (no guideline) 

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 22). 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 

further noted that stable effluent concentration of the active attained peak concentration in 7 day 

cyclic fashion consecutively. 

For facility 2, which is in used on a regular basis, 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 22. 
Docket Number: EPA-HQ-OPP-2012-0811 

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Table 22 - Textile Monitoring Facility Characteristics 

Application/ 

Parameter/ 

Characteristics 

Facility # 1 Facility # 2 Comments 

Use pattern Intermittently used Constantly used - 

Amount of triclosan 

used during study 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 a 3.8 MG Aeration lagoon 

1 & 2 

Clarifier volume 

(MG) 

0.147/operation 

(2 in operation) 0.021 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 23 - Textile Triclosan and Methyl Triclosan Monitoring Concentrations 

Analyte Average (μg/L) Maximum (μg/L) 

Triclosan Facility 1 

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

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APPENDIX C: Ecotoxicology 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 24 - 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 

Triclosan99.7

% 

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

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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. 

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

Page 75 of 116

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 a 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 

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

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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 

Page 77 of 116

Table 25 - 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 

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

Page 78 of 116

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-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 

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

Page 79 of 116

Species % Purity 

Test Type/ 

Temp/ 

pH/ 

Hardness 

or 

Salinityb

Endpoint 

(ug ai/L)a

Toxicity 

Category

Study Classification/ 

Source/ 

Comments 

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 80 of 116

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

Page 81 of 116

Species Method1 Chemical 

Purity Endpoint pH Effect Conc. (μg/L) 

Reference/ 

Comments 

Rainbow Trout, 

Oncorhynchus mykiss 96-h LC50 350 Ciba 1998** 

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 

Page 82 of 116

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 27 - 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 83 of 116

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 oC/ 

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 84 of 116

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 28 - 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 50-108 Survival Orvos et al. 2002 

Cladoceran (<24 hr), 

Ceriodaphnia dubia LC ≥96.1% 8.5 339->339 Survival 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 - 23-230 Survival Fraker and Smith 2004 

Northern leopard frog 

Rana pipiens ELS - 230->230 Growth Fraker and Smith 2004 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 85 of 116

Species Test Type Chemical 

(% purity) pH 

Chronic Limits 

(NOAEC-LOAEC)

(μg/L) 

Reference/ 

Comments 

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->32.3 Survival 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 29 - 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 

No growth measurements, no 

reproduction effect measurements 

(length/weight) made on the larvae 

Estuarine/Marine Fish and Invertebrates-Triclosan

For triclosan, material preservative uses, an acute toxicity study with an estuarine/marine fish, a 

mollusk16, and a shrimp17 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 D) 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 110 ppb for the mysid, 

Americamysis bahia. 

 

16 Embryo-larvae or shell deposition 

17 Penaeidae or Mysidacea 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 86 of 116

Benthic Invertebrates

For triclosan, material preservative uses, sediment toxicity studies are used because triclosan and 

methyl-triclosan are expected to adsorb to aquatic sediments (Koc = 8417-23,380 ml/g). One 

chronic study (no guideline no.) 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 

parent triclosan. No additional sediment testing is expected to be required. 

Aquatic Plants

For triclosan, material preservative uses, testing with four nonvascular species (a freshwater 

diatom18, a marine diatom19, a green algae20, and a cyanobacterium21) 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 30 - 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 

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 

 

18 Navicula pelliculosa 19 Skeletonema costatum 20 Pseudokerscheneria subcapitatum [formerly Selanastrum capricornutum] 21 Anabaena flos-aquae
Docket Number: EPA-HQ-OPP-2012-0811 

Page 87 of 116

Species % Purity 

Test Type/ 

Temp/ pH/ 

Hardb

Endpoint 

(ug ai/L) 

Study Classification/ 

Source/ 

Comments 

Lemna gibba, 

Duckweed 99.5 S 7-d IC50 > 62.5 ppb NOEC < 12,5 ppb 

Acceptable 

MRID 444228-01 

Table 31 - 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 

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

Page 88 of 116

Species Purity Method 1

Study 

Duration

(days) 

Effect Measured pH NOEC

(μg/L)

LOEC 

(μg/L) 

ICx 

(μg/L) Reference 

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 alga 

Anabaena flos-aquae ≥96.1% S, M 4 IC25(growth) 7.5 - - 0.67 Orvos et al.

2002 

Blue-green alga 

Anabaena flos-aquae ≥96.1% S, M 4 IC50(growth) 7.5 - - 0.97 Orvos et al.2002 

Blue-green alga 

Anabaena flos-aquae ≥96.1% S,U 4 IC50(growth – biomass) 7.5 - - 1.6 Orvos et al.

2002 

Blue-green alga 

Anabaena flos-aquae ≥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

Table 32 - 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. 2009 

Only 3 concs 

Green alga, 

Ulothrix sp. - 14 d Growth 7.8 10 >10 >10 Lawrence et al. 2009 Only 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. 2005 Endpoint 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 89 of 116

Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC 

(μg/L) 

Reference/ 

Comments 

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. 2009 Only 3 concs 

Duckweed, 

Lemna minor >99% 24 hr Fluorescence 

inhibition EC50 1,692 Küster et al. 2007 

Duration 

Macrophyte, 

Elodea canadensis >97% 72 hr Chlorophyll-a 8.8-

9.0 <3 3 <3 Heilman 2008 

Duration 

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 

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. 2008 

Excessive solvent 

Midge (12 d), 

Chironomus dilutes ≥97% 10 d EC50, Survival 8.4 - - 400 Dussault et al. 2008 Excessive 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 
Docket Number: EPA-HQ-OPP-2012-0811 

Page 90 of 116

Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC 

(μg/L) 

Reference/ 

Comments 

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 2005 Unmeasured schronic test

Cladoceran (<24 hr), 

Daphnia magna 

Analytical 

grade 30 days Growth (length) 8.4 10 >10 >10 Flaherty and Dodson 2005 Unmeasured chronic test

Cladoceran (<24 hr), 

Daphnia magna 

Analytical 

grade 30 days Resting egg 

production 8.4 10 >10 >10 Flaherty and Dodson 2005 

Unmeasured chronic test

Cladoceran (<24 hr), 

Daphnia magna 

Analytical 

grade 30 days Fecundity 8.4 10 >10 >10 Flaherty and Dodson 2005 Unmeasured chronic test

Cladoceran (<24 hr), 

Daphnia magna 

Analytical 

grade 30 days Sex ratio 8.4 1 10 3.162 Flaherty and Dodson 2005 Unmeasured chronic test

Cladoceran (<24 hr), 

Daphnia magna ≥96.1% 21 days Survival - 200 1000 447.2 Orvos et al. 2002 Unmeasured chronic test

Amphipod (7-14 d), 

Hyalella azteca ≥97% 10 d LC50 7.7 - - 200 Dussault et al. 2008 

Excessive solvent 

Amphipod (7-14 d), 

Hyalella azteca ≥97% 10 d EC50, Growth 7.7 - - 250 Dussault et al. 2008 Excessive 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 

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

Page 91 of 116

Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC 

(μg/L) 

Reference/ 

Comments 

Japanese medaka 

(eggs), 

Oryzias latipes 

Analytical 

grade 14 dph IC50

Survival 7.0 - - 400 Tatarzako et al. 2004 

Duration 

Zebrafish (eggs), 

Danio rerio 

Analytical 

grade 9 dph IC25Survival 7.0 - - 160 Tatarzako et al. 2004 Duration 

Zebrafish (eggs), 

Danio rerio 

Analytical 

grade 9 dph IC50Survival 7.0 - - 220 Tatarzako et al. 2004 

Duration 

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. 2009 

Duration 

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 

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

Page 92 of 116

Species Purity Duration Effect 

Measured pH NOEC(μg/L)

LOEC

(μg/L)

MATC 

(μg/L) 

Reference/ 

Comments 

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 2009 Endpoint 

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 

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. 2010 

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

Page 93 of 116

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 33 - 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 

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 94 of 116

REFERENCES—ECOTOXICOLOGY DATA 

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. 

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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. 

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Barber, L.B., S.H. Keefe, R.C. Antweiler, H.E. Taylor and R.D. Wass. 2006a. Accumulation of 

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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 

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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, 

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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. 
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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. 

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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. 

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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. 

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 

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http://yosemite.epa.gov/sab/SABPRODUCT.NSF/b5d8a1ce9b07293485257375007012b7/E37

FB6980DCDD9B585257532005F6F2C/$File/EPA-SAB-09-007-unsigned.pdf].
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stream-water quality and relations to land use in Johnson County, Northeastern Kansas, 

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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. 

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treatment plant and the influent and effluent of an experimental constructed wetland. 

Environ. Toxicol. Chem. 25(2): 367-372. 

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environment. J. Hazard. Mater. doi:10.1016/j.jhazmat.2010.02.082. 
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APPENDIX D: 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) 

Wat Sol: 23.45 (mg/L, EPISuite WSKowwin v1.43 Estimate) 
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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: 

--------------------------------- 

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50) 
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Maximum LogKow: 6.4 (Green Algae EC50) 

Maximum LogKow: 8.0 (ChV) 

Web-ICE 

Surrogate Species Predicted Species Predicted Values Actual Value Acute 95% LL 

Rainbow trout (288 ppb) Fathead minnow 714.8 514.8 260 

Fathead minnow (260 ppb) Rainbow trout 141 97 288 

Fathead minnow (260 ppb) Bluegill sunfish 188 121 370 

Ceriodaphnia dubia (235 

ppb) Daphnia magna 143 17 

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 

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 
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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) 
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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 

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 
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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 

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 
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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 

Surrogate Species: Daphnid (Daphnia magna) 

Predicted Species: Mysid (Americamysis bahia) 

Surrogate Acute Toxicity (log value) Predicted Acute Toxicity (log value) 

260

μg/L (2.41) 

109.65 μg/L (2.04) 

Select Confidence Interval: Lower Limit Upper Limit 

95% 77.17 μg/L 155.80 μg/L 

Model Information 

Intercept: 0.087748 

Slope: 0.808413 

Degrees of Freedom (N-2): 135 
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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 E: 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 34 - 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 = 

Tetrachlorodibenzofuran; PeCDF = Pentachlorodibenzofuran; HxCDF = Hexachlorodibenzofuran; HpCDF = 

Heptachlorodibenzofuran; OCDF = octachlorodibenzofuran 
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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 Concentrat ion *

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.