UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

   OFFICE OF

                                                                        
                                    PREVENTION, PESTICIDES AND 

            TOXIC SUBSTANCES

September 11, 2008

MEMORANDUM

SUBJECT:		Revised Ecological Hazard and Environmental Risk Assessment
Science Chapter for the Triclosan Reregistration Eligibility Decision
(RED) Document

			DP Barcode:  343548		Reregistration Case No.:  2340

FROM:		Richard C. Petrie, Agronomist, Team 3 Leader

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510P)

TO:			Mark Hartman, Branch Chief

Diane Isbell, Team Leader

Regulatory Management Branch II

Antimicrobials Division (7510P)

Timothy McMahon, Risk Assessor

THRU:		Norman Cook, Branch Chief

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510P)

Chemical Name	PC Code	CAS#		Common Names

5-Chloro-2-	54901		3380-34-5	Triclosan

  (2,4-dichlorophenoxy)phenol

Attached is the Ecological Hazard and Environmental Risk Assessment
Science Chapter for the Triclosan RED Document.

ECOLOGICAL HAZARD AND ENVIRONMENTAL 

REVISED RISK ASSESSMENT CHAPTER

Triclosan

PC Code: 054901

CASE No.: 2340

09/11/08

Richard C. Petrie, Agronomist, Team 3 Leader

Antimicrobials Division

Office of Pesticide Programs

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW

Washington, DC 20460

Table of Contents

												    Page

Executive Summary
………………………………………………………………
……………… 5

1.  Ecological Toxicity Data . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6  

A.  Toxicity to Terrestrial Animals . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . .6 

1.  Birds, Acute  . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . 6

2.  Birds, Subacute. . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . 8 

3.  Mammals, Acute and Chronic . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . .9  

B.  Toxicity to Aquatic Animals . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . .9 

1.  Freshwater Fish, Acute . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .9  

2.  Freshwater Invertebrates, Acute . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .10  

3.  Estuarine and Marine Organisms, Acute . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . .11

4.  Aquatic Organisms, Chronic . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .12 

C.  Toxicity to Plants . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . ..12

II.  Risk Assessment and Risk Characterization . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .  . . ..13

A.  Environmental Fate Assessment Summary . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .. . . . .14 

B.  Environmental Exposure And Qualitative Environmental Risk
Assessment… . .. . . . . ..15 

C.  Endangered Species Considerations . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . .  . . . . . . . . . . .17

III.  Confirmatory Data Required. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .. . . . . . . . . ..18   

IV.  Label Hazard Statements for Terrestrial and Aquatic Organisms. . .
. . . . . . . .  . . . . . . . . .. 19

V.  References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . . . . . 20

LIST OF TABLES

																			  Page

Table 1 – Acute Oral Toxicity of Triclosan to Birds. …. . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .8 

				

Table 2 – Subacute Oral Toxicity of Triclosan to Birds. . . . . . ….
. . . . . . . . . . . . . . . . . . . . . . 9

Table 3 – Acute Toxicity of Triclosan to Freshwater Fish. . . . . . .
. . . . . …. . . . . . . . . . . . . . . 10

Table 4 – Acute Toxicity of Triclosan to Freshwater Invertebrates. . .
. . . …. . . . . . . . . . . . . . 11 

Table 5 – Chronic Toxicity of Triclosan to Freshwater Organisms. . . .
…. . . . . . . . . . . . . . . . 12

Table 6 – Toxicity of Triclosan to Aquatic Plants. . . . . . . . . . .
. …. . . . . . . . . . . . . . . . . . . . ..13

Ecological Hazard and Environment Risk Assessment

For Triclosan

Executive Summary:

	Only a small portion of the uses of triclosan are regulated by the U.S.
EPA and therefore covered in this document.  Triclosan is currently
registered by the EPA as a bacteriostat, fungicide/fungistat and
mold/mildewcide for materials preservation, residential and public
access premises and commercial, institutional and industrial premises
and equipment.   Its materials preservation uses include: adhesives,
fabrics, vinyl, latex, plastics, polyethylene, polyurethane, synthetic
polymers, styrene, floor wax emulsions, rope, textiles, caulking
compounds, sealants, coatings, polypropylene, rubber, inks, cellulosic
materials, slurries, films and latex paints.  The residential and public
access premises uses include: brooms, mulch, floors, shower curtains,
awnings, tents, mattresses, toothbrushes, toilet bowls, urinals, garbage
cans, refuse container liners, insulation, concrete mixtures, grouts,
air filter materials, upholstery fabrics, and rugs/carpets.  The
commercial, institutional and industrial premises and equipment uses
include: conveyor belts, fire hoses, dye bath vats and ice making
equipment. 

	Assessment Based on Published Literature Including USGS Monitoring:  An
ecological risk assessment is not typically conducted for the types of
uses registered for triclosan.  However, since triclosan has been
detected in natural waters, EPA performed a qualitative environmental
risk assessment using monitoring levels of triclosan found in waterways
and toxicity values from the tables in section I to develop risk
quotients (RQs) and compare them to levels of concern (LOCs) for
triclosan.  LOCs were not exceeded for fish but were exceeded for
aquatic plants.  There were no acceptable acute toxicity studies for
freshwater invertebrates or estuarine and marine organisms nor were
there any acceptable chronic toxicity studies available for aquatic
organisms.  Therefore, risk to these species could not be assessed.

	Assessment Based On Consumer Environmental Modeling:  Additionally, EPA
performed consumer environmental modeling for triclosan [see attached
Appendix (Estimates of Exposures and Risks To Aquatic Organisms From
Releases of Triclosan to Surface Water as a Result of Uses Under EPA’s
Jurisdiction) and the revised environmental fate chapter for triclosan].
  The outcome of this consumer environmental modeling is that EPA
concludes that for aquatic animals and plants (vascular and
non-vascular), estimated concentrations of triclosan in surface water do
not exceed concentrations of concern for acute risk presumptions for any
of these organisms.  What this means is that the Agency can reasonably
conclude that the antimicrobial uses of triclosan (e.g.,
triclosan-treated plastic and textile items in households) are unlikely
to contribute significant quantities of triclosan into household
wastewater and eventually to surface water.

	Assessment For Industrial Use Scenarios:  As discussed in the revised
environmental fate chapter, little is known about how much, if any,
triclosan is released from industrial sites (where triclosan is
incorporated into plastic and textile items) into effluents and the
environment (e.g., surface waters).  Considering this, the Agency is
requiring that the registrants perform environmental modeling and
monitoring to address this issue.  Until EPA receives these data we are
unable to calculate risk quotients specific to these industrial
scenarios.

Data Gaps:  

	Environmental modeling and monitoring specific to plastic and textile
facilities, where triclosan is incorporated into these items, is
required.  The registrant is required to sample effluents from such
facilities and receiving (surface) waters adjacent to these facilities,
determining the extent and duration of triclosan and major
degradates/metabolites (e.g., triclosan methyl). Prior to beginning the
environmental monitoring the registrant must submit a protocol to the
Agency for approval.

The available published literature indicates the potential for triclosan
to bioconcentrate and bioaccumulate in the environment.  In order to
better characterize this, the Agency is requiring the following four
studies: 

Oyster bioconcentration study – BCF (850.1710) [Technical Grade Active
Ingredient (TGAI)] or Pure Active Ingredient, Radio-Labeled (PAIRA);

Fish bioconcentration study – BCF (850.1730) (TGAI or PAIRA);

Chironomid sediment toxicity test (850.1790) (TGAI or PAIRA); and

Aquatic food chain transfer test (850.1850) (TGAI or PAIRA).

	Prior to beginning these four studies the registrant must submit
protocols to the Agency for approval.

	Additionally, depending upon the results of the modeling and monitoring
effort and the above four studies, the following ecological effects data
may be required:

Freshwater invertebrate acute study (850.1010) [Technical Grade Active
Ingredient (TGAI)];

Estuarine/marine fish acute study (850.1075) (TGAI)];

Estuarine/marine shrimp acute study (850.1035) (TGAI);

Estuarine/marine mollusk acute study (850.1025) (TGAI);

Fish early life-stage (freshwater) study (850.1400) (TGAI);

Aquatic invertebrate (freshwater) life-cycle study (850.1300) (TGAI);

Fish life-cycle study (850.1500) (TGAI);

Oyster bioconcentration study – BCF (850.1710) (major
degradate/metabolite of triclosan – e.g., methyl triclosan);

Fish bioconcentration study – BCF (850.1730) (major
degradate/metabolite of triclosan – e.g., methyl triclosan);

Chironomid sediment toxicity test (850.1790) (major degradate/metabolite
of triclosan – e.g., methyl triclosan);

Aquatic food chain transfer (850.1850) (major degradate/metabolite of
triclosan – e.g., methyl triclosan);

Acute sediment toxicity to freshwater invertebrates (850.1735) (TGAI);

Acute sediment toxicity to estuarine invertebrates (850.1740) (TGAI);

Chronic sediment toxicity to freshwater and/or estuarine invertebrates
(no guideline number) (TGAI); and

Additional plant toxicity testing:  an additional algal toxicity test
(850.5400) with the freshwater green alga, Selenastrum capricornutum
(TGAI); and studies on the rooted freshwater macrophyte, rice (Oryza
sativa) – 850.4225 and 850.4250 (2 tests on seedling emergence and
vegetative vigor) [Typical End-use Product (TEP)].

Label Hazard Statements/Use Recommendations:

Triclosan labels must state:  

“This pesticide is toxic to fish and aquatic invertebrates.”

"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries, oceans, or other waters unless in accordance with the
requirements of a National Pollutant Discharge Elimination System
(NPDES) permit and the permitting authorities are notified in writing
prior to discharge.  Do not discharge effluent containing this product
to sewer systems without previously notifying the local sewage treatment
plant authority.  For guidance contact your State Water Board or
Regional Office of the EPA."

I.	Ecological Toxicity Data

	The toxicity endpoints presented below are based on the results of
ecotoxicity studies submitted to EPA to meet the Agency’s data
requirements for the uses of triclosan.

	A.	Toxicity to Terrestrial Animals

(1)	Birds, Acute 

	In order to establish the toxicity of triclosan to avian species, the
Agency requires an acute oral toxicity study using the technical grade
active ingredient (TGAI).  The preferred-test species is either mallard
duck (a waterfowl) or bobwhite quail (an upland game bird).  The results
of three acute oral toxicity studies, submitted for triclosan, are
provided in the following table (Table 1).



Table 1.  Acute Oral Toxicity of Triclosan to Birds

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint

(mg/kg)	

Toxicity Category	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Mallard duck

(Anas platyrhynchos)	Triclosan 99.7%	LD50 = >2150

NOAEL = 2150

	Relatively nontoxic	Yes (core)

- 14-day test duration

- 19 weeks of age	430226-03

Bobwhite quail

(Colinus virginianus)	Triclosan 99.7%	LD50 = 825

NOAEL = <147	Slightly toxic	Yes (core)

- 14-day test duration

- 21 weeks of age	430226-02

Bobwhite quail

(Colinus virginianus)	Triclosan 3.89%	LD50 = >2000

NOAEL = N.R.

	Relatively nontoxic	Yes (core for formulated product)

	410089-10



	These three acceptable acute oral toxicity studies indicate that
triclosan is slightly toxic to relatively nontoxic to birds on an acute
oral basis. The guideline requirement OPPTS 850.2100/(71-1) is
satisfied.  

(2)	Birds, Subacute

	A subacute dietary study using the TGAI may be 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.  This testing was
required for triclosan.  The preferred-test species is either the
mallard duck or bobwhite quail.  The results of two subacute dietary
toxicity studies, submitted for triclosan, are provided in the following
table (Table 2).



Table 2.  Subacute Oral Toxicity of Triclosan to Birds

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint

(ppm)	

Toxicity Category	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Bobwhite quail

(Colinus virginianus)	Triclosan 99.7%	LC50 (diet) = >5000

NOAEC = 1250	Relatively nontoxic	Yes (core)

-	8-day test duration

-	13 days of age	430226-04

Bobwhite quail

(Colinus virginianus)	Triclosan 

3.89%	LC50 (diet) = >5000

NOAEC = N.R.	Relatively nontoxic	Yes (core for formulated product)

- 8-day test duration

- 7-10 days of age 	410089-11



	The results of these two acceptable studies indicate that triclosan is
relatively nontoxic to avian species through subacute dietary exposure.
These studies fulfill guideline requirement OPPTS 850.2100/ (71-2a –
Bobwhite quail/71-2b – Mallard duck). 

 (3)	Mammals, Acute and Chronic Toxicity

Wild mammal testing is not 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.  Refer to the human toxicology chapter of this RED for
mammalian toxicity data.  Also, refer to the toxicology chapter for
information on triclosan’s potential as an endocrine disruptor.

B.	Toxicity to Aquatic Animals

	The Agency requested that aquatic toxicity studies be conducted with
triclosan since, under typical use conditions, it may be introduced into
the aquatic environment.

(1)	Freshwater Fish, Acute

	In order to establish the acute toxicity of triclosan to freshwater
fish, the Agency requires freshwater fish toxicity studies using the
TGAI.  The preferred test species are rainbow trout (a coldwater fish)
and bluegill sunfish (a warmwater fish).  The results of 5 freshwater
fish acute studies submitted for triclosan are presented in Table 3.



 Table 3.  Acute Toxicity of Triclosan to Freshwater Fish 

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint

(mg/L)	

Toxicity Category	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Rainbow Trout (Oncorhynchus mykiss)	Triclosan

99.3%	LC50 = 0.288

NOAEC = 0.100	Highly toxic	Yes (core)

-	96-hr test duration

-	static test system	439693-01

Fathead minnow

(Pimephales promelas)	Triclosan

99.7%	LC50 = 0.26

LOEC = 0.18

NOAEC = 0.10

	Highly toxic	No (supplemental)

-	96-hr test duration

-	static test system

-  nominal concentrations not verified	430460-01

Bluegill sunfish (Lepomis macrochirus)	Triclosan 3.89%	LC50 = 37.2 

NOAEC = N.R.	Slightly toxic	Yes (core for formulated product)

-  96-hr test duration

-  static test system	410089-13

Rainbow Trout (Oncorhynchus mykiss)	Triclosan 3.89%	LC50 = 23.4

NOAEC = N.R.	Slightly toxic	Yes (core for formulated product)

-	96-hr test duration

-	static test system	410089-12



	Freshwater acute toxicity tests indicate that triclosan is highly toxic
to slightly toxic to fish on an acute basis.  These studies fulfill
guideline requirement OPPTS 850.1075 (72-1a&b).  Because acute toxicity
to fish is <1.0 mg/L, the environmental hazard section of triclosan
labels must state: “This pesticide is toxic to fish.”

	(2)	Freshwater Invertebrates, Acute

	The Agency requires a freshwater aquatic invertebrate study using the
TGAI to establish the acute toxicity to freshwater invertebrates.  The
preferred test species is Daphnia magna.  The results of two studies
submitted for triclosan are provided in the following table (Table 4). 
Note that in a search of the available data on triclosan, the U.S.
EPA’s Office of Water found an EC50 as low as 0.13 mg/L for the
Cladoceran Ceriodaphnia dubia (U.S. EPA, 2007).



	Table 4.  Acute Toxicity of Triclosan to Freshwater Invertebrates

 

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint

(mg/L)	

Toxicity Category	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Waterflea (Daphnia magna)	Triclosan

99.7%	EC50 = 0.39 

NOAEC = 0.10 (a.i.)	Highly toxic	No (supplemental)

-	48-hr test duration

-	static test system

-  nominal concentrations not verified	430460-02

Waterflea (Daphnia magna)	Triclosan 

3.89%	LC50 = 0.42

NOAEC = N.R.	Highly toxic	No (supplemental)

-  48-hr test                duration

-  static test system

-  lack of pH and DO measurements and formulated product used	410089-14





	The results of these studies indicate that triclosan is highly toxic to
freshwater invertebrates.  These studies do not fulfill guideline
requirement OPPTS 850.1010 (72.2a).  However, this data requirement is
dependent upon the results of environmental modeling and monitoring
which are required to support reregistation of triclosan.  Because the
acute aquatic invertebrate toxicity values are < 1.0 mg/L, the
environmental hazard section of triclosan labels must state:  “This
pesticide is toxic to aquatic invertebrates.”

(3)	Estuarine and Marine Organisms, Acute

	Acute toxicity testing with estuarine and marine organisms using the
TGAI is required when the end-use product is intended for direct
application to the marine/estuarine environment or effluent containing
the active ingredient is expected to reach this environment.  The
preferred fish test species is the sheepshead minnow.  The preferred
invertebrate test species are mysid shrimp and eastern oysters.  At this
time this testing is not required for triclosan, but is dependent upon
the results of environmental fate data which may be required.  (See
triclosan environmental fate chapter and comments above on potential
data requirements).  No studies have been submitted to fulfill these
data requirements (OPPTS 850.1075/(72-3a), OPPTS 850.1035/(72-3c) and
OPPTS 850.1025/(72-3b)).



(4)	Aquatic Organisms, Chronic

	Chronic toxicity testing (fish early life stage and aquatic
invertebrate life cycle) is required for pesticides when certain
conditions of use and environmental fate apply.  The preferred
freshwater fish test species is the fathead minnow.  The preferred
freshwater invertebrate is Daphnia magna.  At this time this testing is
not required for triclosan, but is dependent upon the results of
environmental modeling and monitoring which are required to support
reregistation of triclosan.  (See revised triclosan environmental fate
chapter and comments above on potential data requirements).  The results
of one toxicity study submitted for triclosan is presented in Table 5. 
Note that in a search of the available data on triclosan, the U.S.
EPA’s Office of Water found a NOEC as low as 0.006 mg/L for the
Cladoceran Ceriodaphnia dubia (U.S. EPA, 2007).

Table 5.  Chronic Toxicity of Triclosan to Freshwater Organisms

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint

(mg/L)	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Waterflea 

(Daphnia magna)	Triclosan

% purity unknown	LOEC = <0.1388

NOAEC = N.R.

	No (supplemental)

-  21-day test             duration 

-  static renewal test     system

-  growth not measured as a chronic endpoint

-  % a.i. not given 

-  raw data missing

-  concentration analysis insufficient	437407-01

	

No fathead minnow study has been submitted. The study on the waterflea
does not fulfill the guideline requirement for a chronic aquatic
invertebrate study (OPPTS 850.1300).

Toxicity to Plants

	Non-target plant phytotoxicity testing is required for pesticides when
certain conditions of use and environmental fate apply.  At this time
this testing is not required for triclosan, but is dependent upon the
results of environmental fate data which may be required.  (See
triclosan environmental fate chapter and comments above on potential
data requirements).  However, testing has been conducted with triclosan
on several aquatic plant species.  Testing is normally conducted with
one species of aquatic vascular plant (Lemna gibba) and four species of
algae:  (1) freshwater green alga, Selenastrum capricornutum, (2) marine
diatom, Skeletonema costatum, (3) freshwater diatom, Navicula
pelliculosa, and (4) bluegreen cyanobacteria, Anabaena flos-aquae.  The
rooted aquatic macrophyte rice (Oryza sativa) is also tested in seedling
emergence and vegetative vigor tests.

	Four studies that evaluate the toxicity of triclosan to freshwater
aquatic plants have been submitted. Results of these studies are
presented in Table 6.  Note that in a search of the available data on
triclosan, the U.S. EPA’s Office of Water found an EC50 as low as
0.0007 mg/L for the green alga Scenedesmus subspicatus and an EC25 as
low as 0.00067 mg/L for the blue-green alga Anabaena flos-aquae (U.S.
EPA, 2007).

Table 6.  Toxicity of Triclosan to Aquatic Plants

Species	

Chemical,

% Active Ingredient

(a.i.)

Tested	

Endpoint 

(mg/L)	

Satisfies Guidelines/

Comments	

Reference

(MRID No.)

Marine Diatom (Skeletonema costatum)	Triclosan 

99.5%	EC50 = >0.066

NOEC = 0.0126	Yes (core)

-  96-hour test duration

-  static test system	444228-01

Freshwater Diatom (Navicula pelliculosa)	Triclosan 

99.5%	EC50 = 0.016

NOEC = 0.005	Yes (core)

-  96-hour test duration

-  static test system	444228-01

Bluegreen Cyanobacteria (Anabaena flos-aquae)	Triclosan 

99.5%	EC50 = 0.0012

NOEC = N.R.	Yes (core)

-  96-hour test duration

-  static test system	444228-01

Duckweed (Lemna gibba)	Triclosan 

99.5%	EC50 = >0.0625

NOEC = 0.0125	Yes (core)

-	7-day test duration

-	static test system	444228-01



	

The guideline requirement for an algal toxicity test (850.5400, 123-2)
is partially fulfilled.  One additional algal toxicity test under
850.5400 is outstanding: a test with the freshwater green alga,
Selenastrum capricornutum.  The other non-target aquatic plant toxicity
requirement, floating freshwater aquatic macrophyte duckweed (Lemna
gibba) – guideline 850.4400 - is satisfied.  Studies on the rooted
freshwater macrophyte rice (Oryza sativa) – 850.4225 and 850.4250 (2
tests on seedling emergence and vegetative vigor) -- have not been
submitted.  

II.	Risk Assessment and Characterization

	The triclosan uses that EPA regulates are classified as “indoor”
uses.  An ecological risk assessment is not typically conducted for the
types of uses registered for triclosan.  However, since triclosan has
been detected in natural waters (see triclosan environmental fate
chapter), EPA has performed a qualitative environmental risk assessment
using monitoring levels of triclosan found in waterways and toxicity
values from the tables in section I to develop risk quotients (RQs) and
compare them to levels of concern (LOCs) for triclosan.

	 A.        Environmental Fate Assessment Summary 

	Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol] is a white
crystalline powder with low solubility in water (12 ppm).  Triclosan is
hydrolytically stable under abiotic and buffered conditions over the pH
4-9 range based on data from a preliminary test at 50°C. 
Photolytically, Triclosan degrades rapidly under continuous irradiation
from artificial light at 25°C in a pH 7 aqueous solution, with a
calculated aqueous photolytic half-life of 41 minutes.  One major
transformation product has been identified, DCP (2,4-dichlorophenol),
which was a maximum of 93.8-96.6% of the applied at 240 minutes
post-treatment.

	In soil, triclosan is expected to be immobile based on an estimated Koc
of 9,200.  Triclosan is not expected to volatilize from soil (moist or
dry) or water surfaces based on an estimated Henry’s Law constant of
1.5 x 10-7 atm-m3/mole.  Triclosan exists partially in the dissociated
form in the environment based on a pKa of 7.9, and anions do not
generally adsorb more strongly to organic carbon and clay than their
neutral counterparts.  In aquatic environments, triclosan is expected to
adsorb to suspended solids and sediments and may bioaccumulate (Kow
4.76), posing a concern for aquatic organisms.  There is a low to
moderate potential for bioconcentration in aquatic organisms based on a
BCF range of 2.7 to 90.

	Hydrolysis is not expected to be an important environmental fate
process due to the stability of triclosan in the presence of strong
acids and bases.  However, triclosan is susceptible to degradation via
aqueous photolysis, with a half-life of <1 hour under abiotic
conditions, and up to 10 days in lake water.  An atmospheric half-life
of 8 hours has also been estimated based on the reaction of triclosan
with photochemically produced hydroxyl radicals.  Additionally,
triclosan may be susceptible to biodegradation based on the presence of
methyl-triclosan following wastewater treatment.

	  SEQ CHAPTER \h \r 1 Of the published literature studies on the
occurrence of triclosan in waste water treatment plants, treatment plant
efficiency, and open water measurements of triclosan, the majority
suggest that aerobic biodegradation is one of the major and most
efficient biodegradation pathways (70-80%) through which triclosan and
its by-products are removed from the aquatic environment, with actual
efficiencies ranging from 53-99% (Kanda et al., 2003) in activated
sludge plants, and trickle down filtration ranging from 58-86% (McAvoy
et al., 2002).  Another pathway of removing triclosan from water in
wastewater treatment plants is through the sorption of triclosan and
associated by-products to particles and sludge (10-15%) because of the
chemical’s medium to high hydrophobicity.  Benchtop fate testing of
triclosan found that 1.5-4.5% was sorbed to activated sludge and 81-92%
was biodegraded (Federle et al., 2002).

  

B.	Environmental Exposure and Qualitative Environmental Risk Assessment

Risk assessment integrates the results of the exposure and ecotoxicity
data to evaluate the likelihood of adverse ecological effects. One
method of integrating the results of exposure and ecotoxicity data is
called the quotient method.  For this method, risk quotients (RQs) are
calculated by dividing exposure estimates by ecotoxicity values, both
acute and chronic:  

       

           RQ = EXPOSURE/TOXICITY 

 

RQs are then compared to levels of concern (LOCs).  These LOCs are
criteria used by OPP to indicate potential risk to nontarget organisms
and the need to consider regulatory action.  The criteria indicate that
a pesticide used as directed has the potential to cause adverse effects
on nontarget organisms.  LOCs currently address the following risk
presumption categories: (1) acute - the potential for acute risk is
high, regulatory action may be warranted in addition to restricted use
classification; (2) acute restricted use - the potential for acute risk
is high, but this may be mitigated through restricted use
classification; (3) acute endangered species - the potential for acute
risk to endangered species is high, and regulatory action may be
warranted, and (4) chronic risk - the potential for chronic risk is
high, and regulatory action may be warranted, (5) non-endangered plant
risk – potential for effects in non-target plants, and (6) endangered
plant risk – potential for effects in endangered plants.   Currently,
EFED does not perform assessments for chronic risk to plants, acute or
chronic risks to nontarget insects, or chronic risk from granular/bait
formulations to birds or mammals.

The ecotoxicity test values (measurement endpoints) used in the acute
and chronic risk quotients are derived from required studies.  Examples
of ecotoxicity values derived from short-term laboratory studies that
assess acute effects are: (1) LC50 (fish and birds), (2) LD50 (birds and
mammals), (3) EC50 (aquatic plants and aquatic invertebrates) and (4)
EC25 (terrestrial plants).  Examples of toxicity test effect levels
derived from the results of long-term laboratory studies that assess
chronic effects are: (1) LOAEC (birds, fish, and aquatic invertebrates),
and (2) NOAEC (birds, fish and aquatic invertebrates). For birds and
mammals, the NOAEC generally is used as the ecotoxicity test value in
assessing chronic effects, although other values may be used when
justified. However, the NOAEC is used if the measurement endpoint is
production of offspring or survival.

Risk presumptions, along with the corresponding RQs and LOCs are
tabulated below.



Risk Presumptions for Terrestrial Animals



Risk Presumption	

RQ	

LOC



Birds and Wild Mammals



Acute Risk	

EEC1/LC50 or LD50/sqft2 or LD50/day3	

0.5



Acute Restricted Use	

EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 mg/kg)	

0.2



Acute Endangered Species	

EEC/LC50 or LD50/sqft or LD50/day 	

0.1



Chronic Risk	

EEC/NOAEC	

1

 1  abbreviation for Estimated Environmental Concentration (ppm) on
avian/mammalian food items   

 2    mg/ft2             	3  mg of toxicant consumed/day

   LD50 * wt. of bird             	LD50 * wt. of bird  

Risk Presumptions for Aquatic Animals	 



Risk Presumption	

RQ 	

LOC



Acute Risk	

EEC1/LC50 or EC50	

0.5



Acute Restricted Use	

EEC/LC50 or EC50	

0.1



Acute Endangered Species	

EEC/LC50 or EC50	

0.05



Chronic Risk	

EEC/MATC2 or NOAEC	

1



 1  EEC = (ppm or ppb) in water

 2  MATC = maximum allowable toxicant concentration

Risk Presumptions for Plants	

	





Risk Presumption	

RQ	

LOC



Terrestrial and Semi-Aquatic Plants 



Acute Risk	

EEC/EC25	

1



Acute Endangered Species	

EEC/EC05 or NOAEC	

1



Aquatic Plants



Acute Risk	

EEC1/EC50	

1



Acute Endangered Species	

EEC/EC05 or NOAEC 	

1



EEC = (ppb/ppm) in water 

Risk Quotients – Based On Published Literature, Submitted Data, and
USGS Monitoring Data

	Triclosan was found in approximately 36 US streams (Kolpin et al.,
2002), where effluent from activated sludge waste water treatment
plants, trickle down filtration, and sewage overflow are thought to
contribute to the occurrence of triclosan in open water. For this study,
the U.S. Geological Survey surveyed a network of 139 streams across 30
states during 1999 and 2000.  The selection of sampling sites was biased
toward streams susceptible to contamination (i.e. downstream of intense
urbanization and livestock production). The median concentration of
triclosan was 140 ng/L and the maximum concentration detected was 2300
ng/L (Kolpin et al., 2002).  Discharge into U.S. surface waters has
resulted in other researchers finding triclosan from the low ng/L levels
to a maximum of 2.3 µg/L (U.S. EPA, 2007).

From the toxicity tables in section I above, the highest toxicity in an
acceptable fish study was achieved in a study on the rainbow trout
(Oncorhynchus mykiss).  The LC50 value obtained in this study was 0.288
mg/L (MRID 439693-01).  There were no acceptable acute toxicity studies
for freshwater invertebrates or estuarine and marine organisms nor were
there any acceptable chronic toxicity studies available for aquatic
organisms.  Therefore, risk to these species cannot be assessed.  The
highest toxicity in an acceptable aquatic plant toxicity study was
achieved in a study on the bluegreen cyanobacteria (Anabaena
flos-aquae).  The EC50 value obtained in this study was 0.0012 mg/L and
no NOEC was reported (MRID 444228-01).   

For aquatic animals the LOC ranges from 0.05 for endangered species to 1
for chronic risks.  Comparing the maximum concentration of triclosan
found in U.S. surface waters (2.3 µg/L or 0.0023 mg/L) to the highest
toxicity found in a fish acute study (0.288 mg/L), an RQ of 0.008 is
obtained.  This is less than all LOCs for aquatic animals and therefore
the potential for triclosan to cause adverse effects on fish is not
high.

For aquatic plants the LOC is 1.  Comparing the maximum concentration of
triclosan found in US streams (2.3 µg/L or 0.0023 mg/L) to the highest
toxicity found in aquatic plants (0.0012 mg/L), an RQ of 1.92 is
obtained.  This is higher than the LOC and therefore the potential for
acute risk to aquatic plants from triclosan exists.  An evaluation of
the effects of triclosan on natural freshwater algae located above and
below a wastewater treatment plant indicates that a concentration of
0.00015 mg/L caused a significant reduction in Chlamydomonas sp. (RQ of
15.33).  This is considered supplemental data, but points to the need
for further research on shifts in algal communities, reductions in
biomass, and effects on higher trophic levels (Wilson et al., 2003).  A
meta-analysis of literature, plus exposure modeling were used to conduct
a probabilistic assessment of triclosan.  This analysis sheds light on
the difficulties associated with relating laboratory data to field
effects and concludes that additional studies may be needed to refine
scientific knowledge of metabolites and degradates, bioaccumulation
factors, endocrine-related effects, and community level impacts.  The
exposure models used in this study (GREAT-ER and PhATE) have not been
peer reviewed by the Agency (Capdevielle et al., 2008).  

The triclosan degradation product methyl triclosan was studied by the
National Oceanic and Atmospheric Administration’s (NOAA) Hollings
Marine Laboratory to assess it’s toxicity to the estuarine organisms
grass shrimp (Paleamonetes pugio), bioluminescent bacterium (Vibrio
fischeri), and the phytoplankton Dunaliella tertiolecta.  Methyl
triclosan is believed to be more persistent in the environment that its
parent and have a higher potential to bioaccumulate since it is more
lipophilic.  However, mechanisms of transformation (and subsequent
uptake) if by microbes in the gut or in the seawater, are unclear
(DeLorenzo et al, 2007).  Uncertainties exist as to the potential for
triclosan degradates to contribute to acute and/or chronic impacts on
aquatic organisms and ecosystems.

Risk Quotients – Based On Consumer Environmental Modeling

For a full discussion of the assumptions, approaches, and techniques
used in the Agency’s (consumer) environmental modeling effort for
triclosan, the reader is referred to the attached Appendix (Estimates of
Exposures and Risks To Aquatic Organisms From Releases of Triclosan to
Surface Water as a Result of Uses Under EPA’s Jurisdiction) and the
environmental fate chapter for triclosan.  These documents discuss in
detail how the Agency performed this modeling effort.  Thus, for brevity
only the conclusions of this consumer environmental modeling will be
presented here.

Consumer Environmental Modeling Results:  As outlined in the attached
Appendix, the Agency performed screening level environmental modeling
and concluded that, if all of the triclosan produced annually for
antimicrobial uses is released to surface water as a result of consumer
uses, then:

Aquatic Animals:  Estimated concentrations of triclosan in surface water
do not exceed concentrations of concern for acute risk presumptions for
aquatic animals.  (See Appendix, Table 2.)

Aquatic Animals:  Estimated concentrations of triclosan in surface water
do not exceed concentrations of concern for endangered species risk
presumptions for aquatic animals.  (See Appendix, Table 3.)

Aquatic Vascular Plants:  Estimated concentrations of triclosan in
surface water do not exceed concentrations of concern for endangered
species risk presumptions for aquatic vascular plants (e.g., duckweed,
Lemna gibba).  (See Appendix, Table 4.)

Aquatic Non-Vascular Plants:  Estimated concentrations of triclosan in
surface water do exceed concentrations of concern for acute risk
presumptions for species that represent non-vascular freshwater plants
(i.e., algae).  The number of days of exceedance of the concentration of
concern is 1 day for blue-green algae, 5 days for green algae, and 57
days for Chlamydomonas sp.  (See Appendix, Table 4.)

Adjustments to Consumer Environmental Modeling Results:  As indicated
above, the Agency performed this environmental modeling in an effort to
estimate:

(1) Concentrations of triclosan in surface water [from antimicrobial
uses of triclosan (e.g., triclosan-treated plastic and textile items in
households) to which aquatic organisms may be exposed as a result of
potential releases of triclosan from these consumer uses; and

(2) Number of days per year that the concentration of triclosan in
surface water exceeds the concentration of concern for aquatic
organisms.

A critical assumption in this screening level, modeling analysis was
that all of the triclosan produced annually for antimicrobial uses is
released to surface water as a result of consumer uses.  That is, 100 %
of all triclosan produced annually is released into household wastewater
during washing and rinsing of products treated with triclosan as a
materials preservative or as a functional component.

However, in an effort to check this 100 % release value used above for
consumer scenarios, EPA reexamined available textile leaching data and
determined that the 100 % assumption (for release of triclosan into
household wastewater) is highly unlikely.  Specifically, available data
for textile leaching of triclosan indicate that triclosan leaches from a
variety of fabrics in the range of 0.00 % to 0.55 %. 

Conclusions Based On Adjusted Consumer Environmental Modeling Results: 
Considering the above textile leaching data, one can reduce all
calculations (for estimated triclosan concentrations and concentrations
of concern) presented in the attached Appendix by a factor of 100.  In
doing so, EPA concludes that for aquatic animals and plants (vascular
and non-vascular), estimated concentrations of triclosan in surface
water do not exceed concentrations of concern for acute risk
presumptions for any of these organisms.  What this means is that the
Agency can reasonably conclude that the antimicrobial uses of triclosan
(e.g., triclosan-treated plastic and textile items in households) are
unlikely to contribute significant quantities of triclosan into
household wastewater and eventually to surface water.

Risk Quotients – Industrial Use Scenarios (e.g., Triclosan
Incorporation Into 	Plastics or Textiles In Industrial Setting)

	As discussed in the revised environmental fate chapter, little is known
about how much, if any, triclosan is released from industrial sites
(where triclosan is incorporated into plastic and textile items) into
effluents and the environment (e.g., surface waters).  Considering this,
the Agency is requiring that the registrants perform environmental
modeling and monitoring to address this issue.  Until EPA receives these
data we are unable to calculate risk quotients specific to these
industrial scenarios.

  

      Endangered Species Considerations

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2),
requires all federal agencies to consult with the National Marine
Fisheries Service (NMFS) for marine and anadromous listed species, or
the United States Fish and Wildlife Services (FWS) for listed wildlife
and freshwater organisms, if they are proposing an "action" that may
affect listed species or their designated habitat.  Each federal agency
is required under the Act to insure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse modification
of designated critical habitat.  To jeopardize the continued existence
of a listed species means "to engage in an action that reasonably would
be expected, directly or indirectly, to reduce appreciably the
likelihood of both the survival and recovery of a listed species in the
wild by reducing the reproduction, numbers, or distribution of the
species.  "50 C.F.R. 402.02”.

To facilitate compliance with the requirements of the Endangered Species
Act subsection (a)(2) the Environmental Protection Agency, Office of
Pesticide Programs has established procedures to evaluate whether a
proposed registration action may directly or indirectly reduce
appreciably the likelihood of both the survival and recovery of a listed
species in the wild by reducing the reproduction, numbers, or
distribution of any listed species (U.S. EPA 2004).  After the
Agency’s screening-level risk assessment is performed, if any of the
Agency’s Listed Species LOC Criteria are exceeded for either direct or
indirect effects, a determination is made to identify if any listed or
candidate species may co-occur in the area of the proposed pesticide
use.  If determined that listed or candidate species may be present in
the proposed use areas, further biological assessment is undertaken. 
The extent to which listed species may be at risk then determines the
need for the development of a more comprehensive consultation package as
required by the Endangered Species Act.

For certain use categories, the Agency assumes there will be minimal
environmental exposure, and only a minimal toxicity data set is required
(Overview of the Ecological Risk Assessment Process in the Office of
Pesticide Programs U.S. Environmental Protection Agency - Endangered and
Threatened Species Effects Determinations, 1/23/04, Appendix A, Section
IIB, pg.81).  Chemicals in these categories therefore do not undergo a
full screening-level risk assessment.

	This preliminary analysis indicates that there is a potential for
triclosan use to overlap with listed species and that a more refined
assessment is warranted, to include direct, indirect and habitat
effects.  The more refined assessment should involve clear delineation
of the action area associated with proposed use of triclosan and best
available information on the temporal and spatial co-location of listed
species with respect to the action area.  This analysis has not been
conducted for this assessment.  An endangered species effect
determination will not be made at this time.  

Confirmatory Data Required:

	Environmental modeling and monitoring specific to plastic and textile
facilities, where triclosan is incorporated into these items, is
required.  The registrant is required to sample effluents from such
facilities and receiving (surface) waters adjacent to these facilities,
determining the extent and duration of triclosan and major
degradates/metabolites (e.g., triclosan methyl). Prior to beginning the
environmental monitoring the registrant must submit a protocol to the
Agency for approval.  

	The available published literature indicates the potential for
triclosan to bioconcentrate and bioaccumulate in the environment.  In
order to better characterize this, the Agency is requiring the following
four studies: 

Oyster bioconcentration study – BCF (850.1710) [Technical Grade Active
Ingredient (TGAI)] or Pure Active Ingredient, Radio-Labeled (PAIRA);

Fish bioconcentration study – BCF (850.1730) (TGAI or PAIRA);

Chironomid sediment toxicity test (850.1790) (TGAI or PAIRA); and

Aquatic food chain transfer test (850.1850) (TGAI or PAIRA).

	Prior to beginning these four studies the registrant must submit
protocols to the Agency for approval.

	Additionally, depending upon the results of the modeling and monitoring
effort and the above four studies, the following ecological effects data
may be required:

Freshwater invertebrate acute study (850.1010) [Technical Grade Active
Ingredient (TGAI)];

Estuarine/marine fish acute study (850.1075) (TGAI)];

Estuarine/marine shrimp acute study (850.1035) (TGAI);

Estuarine/marine mollusk acute study (850.1025) (TGAI);

Fish early life-stage (freshwater) study (850.1400) (TGAI);

Aquatic invertebrate (freshwater) life-cycle study (850.1300) (TGAI);

Fish life-cycle study (850.1500) (TGAI);

Oyster bioconcentration study – BCF (850.1710) (major
degradate/metabolite of triclosan – e.g., methyl triclosan);

Fish bioconcentration study – BCF (850.1730) (major
degradate/metabolite of triclosan – e.g., methyl triclosan);

Chironomid sediment toxicity test (850.1790) (major degradate/metabolite
of triclosan – e.g., methyl triclosan);

Aquatic food chain transfer (850.1850) (major degradate/metabolite of
triclosan – e.g., methyl triclosan);

Acute sediment toxicity to freshwater invertebrates (850.1735) (TGAI);

Acute sediment toxicity to estuarine invertebrates (850.1740) (TGAI);

Chronic sediment toxicity to freshwater and/or estuarine invertebrates
(no guideline number) (TGAI); and

Additional plant toxicity testing:  an additional algal toxicity test
(850.5400) with the freshwater green alga, Selenastrum capricornutum
(TGAI); and studies on the rooted freshwater macrophyte, rice (Oryza
sativa) – 850.4225 and 850.4250 (2 tests on seedling emergence and
vegetative vigor) (TEP).

	

IV.	 Label Hazard Statements for Terrestrial and Aquatic Organisms:

Triclosan labels must state:  

“This pesticide is toxic to fish and aquatic invertebrates.”

"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries, oceans, or other waters unless in accordance with the
requirements of a National Pollutant Discharge Elimination System
(NPDES) permit and the permitting authorities are notified in writing
prior to discharge.  Do not discharge effluent containing this product
to sewer systems without previously notifying the local sewage treatment
plant authority.  For guidance contact your State Water Board or
Regional Office of the EPA."

V.  REFERENCES

41008910.  Terrell, Y.  1985.  Acute Oral Toxicity Study of Issue Plus
II; ID No. 88-472; Prepared by American Standards Biosciences Corp. for
Diversey Wyandotte Corporation, Wyandotte, Michigan.

41008911.  Terrell, Y.  1988.  Avian Dietary Quaily (Litmus Test) of
Issue Plus in Bobwhite Quail; Project No. 88-471; Prepared by American
Standard Biosciences Corp. for Diversey Wyandotte Corporation,
Wyandotte, Michigan.

41008912.  Terrell, Y.  1988.  The Acute Toxicity Bioassay of Issue Plus
on Rainbow Trout; Project No. 88-474; Prepared by American Standard
Biosciences Corp. for Diversey Wyandotte Corporation, Wyandotte,
Michigan.

41008913.  Terrell, Y.  1988.  The Acute Toxicity Bioassay of Issue Plus
on Bluegill Sunfish; Project No. 88-473; Prepared by American Standard
Biosciences Corp. for Diversey Wyandotte Corporation, Wyandotte,
Michigan.

41008914.  Terrell, Y.  1988.  Acute Toxicity of Issue Plus on Daphnia
magna; Project No. 88-475; Prepared by American Standard Biosciences
Corp. for Diversey Wyandotte Corporation, Wyandotte, Michigan.

42322101.  Boettcher, J.  1990.  Report on the Acute Toxicity (96h) of
FAT 80, 023/Q to Zebrafish.  Test No. G 069 04.  Prepared by Ciba-Geigy,
Ltd., D&C Product Ecotoxicology, Basel, Switzerland.  Submitted by
Ciba-Giegy Corporation, Greensboro, North Carolina.

42322102.  Wuethrich, V.  1990.  48-Hour Acute Toxicity of FAT 80, 023/Q
to Daphnia magna (OECD-Immobilization Test).  Project No. 262923. 
Prepared by RCC Umweltchemie AG, Itingen, Switzerland.  Submitted by
Ciba-Giegy Corporation, Greensboro, North Carolina.

43022602.  Pedersen, C.A. and B.R. Helsten.  1993.  Triclosan (IRGASAN
DP300(): 14-Day Acute Oral LD50 Study in Bobwhite Quail.  Study
performed by Bio-Life Associates, Ltd., Neillsville, Wisconsin. 
Laboratory Project No. 102-024-03.  Submitted by CIBA-GEIGY Corporation,
Greensboro, North Carolina.

43022603.  Pedersen, C.A. and B.R. Helsten.  1993.  Triclosan (IRGASAN
DP300(): 14-Day Acute Oral LD50 Study in Mallard Ducks.  Study performed
by Bio-Life Associates, Ltd., Neillsville, Wisconsin.  Laboratory
Project No. 102-023-04.  Submitted by CIBA-GEIGY Corporation,
Greensboro, North Carolina.

43022604.  Pedersen, C.A. and B.R. Helsten.  1993.  Triclosan (IRGASAN
DP300(): 8-Day Acute Dietary LC50 Study in Bobwhite Quail.  Study
performed by Bio-Life Associates, Ltd., Neillsville, Wisconsin. 
Laboratory Project No. 102-022-01.  Submitted by CIBA-GEIGY Corporation,
Greensboro, North Carolina.

43046001.  Bowman, J.H.  1990.  Acute Toxicity of D1063.01 (Triclosan:
Irgasan DP300) to Fathead Minnow (Pimephales promelas).  Laboratory
Project ID No. 38655.  Prepared by Analytical Bio-Chemistry
Laboratories, Inc, Columbia, Missouri.  Submitted jointly by Proctor and
Gamble Company and Ciba-Geigy Corp.

43046002.  Forbis, A.D. and J.G. Muckerman.  1990.  Acute Toxicity of
D1063.01 (Triclosan: Irgasan DP300) to Daphnia magna.  Laboratory
Project ID No. 38656.  Prepared by Analytical Bio-Chemistry
Laboratories, Inc, Columbia, Missouri.  Submitted jointly by Proctor and
Gamble Company and Ciba-Geigy Corp.

43740701.  Wuethrich, V.  1990.  Influence of FAT 80023/Q (Irgasan
DP300) on Reproduction of Daphnia magna.  Project No. 262934.  Prepared
by RCC Umweltchemie AG, Itingen, Switzerland.  Submitted by Ciba-Giegy
AG, Basel, Switzerland.

43969301.  Sword, M.C.  1996.  Static Acute Toxicity of Triclosan to
Rainbow Trout.  Study performed by ABC Laboratories, Inc., Columbia,
Missouri.  Laboratory Report No. 42997.  Sponsored by CIBA Chemical
Division, Greensboro, North Carolina.

44422801.  Staveley, J.P. and T.L. Williams.  1997.  Effects of
Triclosan on the Growth and Reproduction of Aquatic Plants.  Study
performed by Carolina Ecotox, Inc., Durham, North Carolina.  Laboratory
Report ID: 21-02-1.  Sponsored by Ciba-Geigy Corporation, Greensboro,
North Carolina.

Capdevielle, M.  R.V. Egmond, M. Whelan, D. Versteeg, M.
Hofmann-Kamensky, J. Inauen, V. Cunningham, and D. Woltering.  2008. 
Consideration of Exposure and Species Sensitivity of Triclosan in the
Freshwater Environment.  Integrated Environmental Assessment and
Management.  Vol. 4 (1):  15-23.  

DeLorenzo, M.E., J.M. Keller, C.D. Arthur, M.C. Finnegan, H.E. Harper,
V.L. Winder, and D.L. Zdankiewicz.  2007.  Toxicity of the Antimicrobial
Compound Tricolsan and Formation of the Metabolite Methyl-Tricolsan in
Estuarine Systems.  Environmental Toxicology.  Vol. 23(2):  224-232.

Federle, T.W., Kaiser, S.K., and Nuck, B.A. 2002. Fate and Effects of
Triclosan in Activated Sludge.  Environmental Toxicology and
Chemistry/SETAC.  21(7): 1330-7.

Kanda, R., Griffin, P., and James, H.A., et al. 2003. Pharmaceutical and
Personal Care Products in Sewage Treatment Works.  Journal of
Environmental Monitoring.  5(5): 823-30.

Kolpin, D.W., Furlong, E.T., Meyer, M.T., et al. 2002. Pharmaceuticals,
Hormones, and Other Organic Wastewater Contaminants in U.S. Streams,
1999-2000: A National Reconnaissance. Environmental Science and
Technology. 36(6): 1202-11.

McAvoy, D.C., Schatowitz, B., Martin, J., et al. 2002. Measurement Of
Triclosan In Wastewater Treatment Systems. Environmental Toxicology and
Chemistry. 21 (7): 1323-9.

U.S. Environmental Protection Agency, Office of Water.  Summary of
Available Aquatic Toxicity Data for Aquatic Life Water Quality Criteria
Development for Triclosan.  Draft: August 16, 2007.

Wilson, G.A., V.H. Smith, F. Denoyelles, Jr., C.K. Larive.  2003. 
Effects of Three Pharmaceutical and Personal Care Products on Natural
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Vol. 37 (9):  1713-1719.



Appendix:

Estimates Of Exposures And Risks To Aquatic Organisms From Releases Of
Triclosan To Surface Water As A Result Of Uses Under EPA’S
Jurisdiction

[NOTE:  Confidential Business Information (CBI) has been removed from
this document]

ESTIMATES OF EXPOSURES AND RISKS TO AQUATIC ORGANISMS FROM RELEASES OF
TRICLOSAN TO SURFACE WATER AS A RESULT OF USES UNDER EPA’S
JURISDICTION

INTRODUCTION

The Regulatory Management Branch II of the Antimicrobials Division (AD)
requested the Risk Assessment and Science Support Branch (RASSB) of AD
to provide estimates of exposures and risks to aquatic organisms from
surface water releases of triclosan from uses under EPA’s
jurisdiction.  Triclosan is regulated by both the U.S. Environmental
Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA).
 The EPA regulates the antimicrobial uses of triclosan when used as a
bacteriostat, fungistat, mildewistat, and deodorizer.  The
FDA-registered uses of triclosan include hand soaps, toothpaste,
deodorants, laundry detergent, fabric softeners, facial tissues,
antiseptics for wound care, and medical devices.  General categories of
antimicrobial uses of triclosan include use in commercial,
institutional, and industrial premises and equipment; residential and
public access premises; and as a materials preservative.  Specific
information on the use profile for triclosan used as an antimicrobial
pesticide is posted on EPA’s website at   HYPERLINK
"http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm" 
http://www.epa.gov/oppsrrd1/REDs/factsheets/triclosan_fs.htm .  Some
common specific uses of triclosan include its use as a materials
preservative in textiles and plastics.

METHODOLOGY AND SCOPE OF THIS ANALYSIS

The Antimicrobials Division of EPA evaluates exposures and risks to
aquatic organisms from releases of antimicrobial pesticides to surface
water.  Antimicrobial pesticides may potentially be released to surface
water during their manufacture, processing, industrial use, commercial
use, and consumer use.  The Exposure and Fate Assessment Screening Tool,
Version 2.0 (E-FAST 2) developed by EPA/OPPTS/OPPT is a screening-level
computer tool that is used to estimate concentrations of a chemical in
surface water to which aquatic organisms may be exposed as a result of
these releases.  The data and tools needed to estimate exposure to
aquatic organisms from releases of a chemical to surface water from
manufacture, processing, industrial use, and commercial use are
different from those needed to estimate exposures to aquatic organisms
from consumer use.  The general population and ecological exposures from
industrial uses module of E-FAST 2 is used to estimate exposure to
aquatic organisms from releases of a chemical to surface water from
manufacture, processing, industrial use, and commercial use.  The
Down-the-Drain module of E-FAST 2 is used to estimate exposure to
aquatic organisms from releases of a chemical to surface water from
consumer use.

Data Required for the General Population and Ecological Exposures Module

Analysis of exposures to aquatic organisms from releases of chemicals to
surface water from manufacture, processing, industrial use, and
commercial use requires data including: (1) the amount of chemical
released on a daily basis to surface water from each facility that
discharges the chemical of concern; (2) the location of facilities that
discharge the chemical of concern to surface water or if that
information is not available, the representative Standard Industrial
Classification (SIC) code for facilities that discharge the chemical of
concern to surface water; (3) the number of days of release per year for
each facility or facility classification that discharges the chemical of
concern; (4) the number of industrial facilities releasing the chemical
of concern to surface water; and (5) concentrations of the chemical of
concern to aquatic organisms.  The ChemSteer model developed by OPPT or
an approach based on this model can be used to estimate the amount of
chemical released to surface water for each day of discharge for each
discharge site.  This information, along with the other input parameters
delineated above can be used to run the general population and
ecological exposures from industrial uses module of E-FAST 2.

Data Required for the Down-the-Drain Module

Analysis of exposures to aquatic organisms from releases of chemicals to
surface water from consumer use requires data including: (1) an estimate
of the wastewater treatment plant influent volume; (2) the percent
removal of the chemical during wastewater treatment; and (3)
concentrations of the chemical of concern to aquatic organisms.  These
input parameters are used to run the Down-the-Drain module of E-FAST 2. 

Approach for Estimating Exposures from Down-the-Drain Releases

For this screening level analysis of exposures to aquatic organisms from
uses of triclosan under EPA’s jurisdiction, a simplifying assumption
is that all of the triclosan under EPA’s jurisdiction is released to
surface water as a result of consumer uses.  Estimates of exposures to
aquatic organisms from releases to surface water from its manufacture,
processing, industrial use, and commercial use are therefore, assumed to
be negligible.  Releases of triclosan to surface water from consumer
uses are assumed to result entirely from disposal of consumer products
into household wastewater. Triclosan is assumed to be released into
household wastewater during washing and rinsing of products treated with
triclosan as a materials preservative or other functional component. 
For this analysis, AD used the Down-the-Drain module of E-FAST to
provide screening-level estimates of potential exposures and risks to
aquatic organisms from releases to household wastewaters from consumer
uses of triclosan.

The methodology for the Down-the-Drain module assumes that household
wastewater undergoes treatment at a local wastewater treatment plant and
that treated effluent is subsequently discharged into surface waters. 
The Down-the-Drain module provides estimates of exposure to aquatic
organisms and exposure to humans from ingestion of drinking water and
fish that may be exposed to these household wastewater releases.  In
addition, there is a probabilistic dilution model (PDM) option that
provides estimates of the number of days per year that the concentration
of a chemical in surface water exceeds the concentration of concern for
aquatic organisms.

This analysis focused on exposure of aquatic organisms to triclosan and
did not consider potential exposure to humans from ingestion of drinking
water and fish contaminated with triclosan.  The PDM option of the
Down-the-Drain module was used to estimate the number of days of
exceedance of concentrations of concern for aquatic organisms downstream
of waste water treatment plants (WWTPs).  Input parameters needed to run
the Down-the-Drain module of E-FAST 2 include: (1) the wastewater
treatment plant (WWTP) influent volume of the chemical; (2) the percent
of chemical removed during wastewater treatment; (3) the
bioconcentration factor (BCF) of the chemical in fish; and (4) the
duration of exposure.  These last two input parameters are used to
estimate exposure to humans from ingestion of drinking water and fish
and are not used to estimate potential exposures to aquatic organisms.
Table 1 presents data for input parameters used to run the
Down-the-Drain module of E-FAST 2.

   TABLE 1- INPUT DATA FOR THE DOWN-THE-DRAIN MODULE OF E-FAST 2

WWTP Influent Volume (kg/yr)	Value removed

Bioconcentration Factor in Fish (BCF)	Value removed 

Percent WWTP removal of Triclosan 	Value removed

Exposure duration (years of use)	Value removed



The percent of chemical removed during wastewater treatment was assumed
to be (Value removed) percent.  Measurements reported from benchtop fate
testing indicated that 81-92 percent of triclosan was biodegraded
(Federle et al., 2002).  There is also potential for triclosan
undergoing wastewater treatment to adsorb to sludge and other solids. 
After a review of available literature and modeling results regarding
the environmental fate of triclosan during wastewater treatment, (…
rest of statement removed…).  Companies that manufacture and import
triclosan reported annual volumes for uses under EPA’s jurisdiction to
be (… rest of statement removed…).  As a simplifying assumption, all
of the triclosan reported to be produced or imported for uses under
EPA’s jurisdiction was assumed to enter the influent of wastewater
treatment plants that receive household wastewaters.

For the PDM option of the Down-the-Drain module, values of the
concentrations of triclosan of concern to aquatic organisms were
selected for acute and endangered species risk presumptions for aquatic
animals and plants using acute toxicity endpoint values for species
intended to represent freshwater fish, freshwater invertebrates, and
aquatic plants.  For the acute risk presumption for aquatic animals, the
concentration of concern was calculated by multiplying the estimated
surface water concentration of triclosan by 0.5.  For the endangered
species risk presumption for aquatic animals, the concentration of
concern was calculated by multiplying the estimated surface water
concentration of triclosan by 0.05.  For the acute and endangered
species risk presumptions for aquatic plants, the concentration of
concern was assumed to be equal to the estimated surface water
concentration for triclosan.  The measurement endpoint used for the
acute risk presumption for aquatic plants is the EC50.  The measurement
endpoint used for the endangered species risk presumption for aquatic
plants is the NOAEC.  Estimates of the number of days of exceedance of
concentrations of concern for aquatic organisms downstream of waste
water treatment plants were generated for both high-end and average case
scenarios.

The Down-the-Drain module of E-FAST 2 provides both high-end
time-averaged surface water concentrations and median time-averaged
surface water concentrations of a chemical released by a wastewater
treatment facility receiving household wastewater. The high-end scenario
uses surface water concentrations based on the 10th percentile stream
dilution factor for streams to which wastewater treatment facilities
that receive household wastewaters discharge.  The average case scenario
uses surface water concentrations based on the 50th percentile stream
dilution factor for streams to which wastewater treatment facilities
that receive household wastewaters discharge.  A stream dilution factor
is calculated by dividing the flow that represents  the receiving stream
flow downstream of a wastewater treatment plant by the wastewater
treatment plant effluent flow.  The stream flow data and stream dilution
factors are ranked and the results are reported in terms of percentiles
of the distribution of data.  To estimate potential acute and chronic
aquatic life impacts, the PDM option uses 1Q10 and 7Q10 stream flows. 
The 1Q10 is the lowest flow for a single day during any 10-year period. 
The 7Q10 is the lowest consecutive 7-day average flow during any 10-year
period.  Estimates for a high-end scenario are based on the averaged
probability of exceedance of the 10 percent of WWTPs that have the
highest probability of exceedance of the COC following treatment based
on the estimated typical daily per capita wastewater volume released. 
Estimates for an average case scenario are based on WWTPs that have an
average probability of exceedance of the COC following treatment based
on the estimated typical daily per capita wastewater volume released. 

AQUATIC EXPOSURE AND RISK ASSESSMENT

Results of the assessment of exposure and risk to aquatic organisms from
uses of triclosan under EPA’s jurisdiction that are disposed in
household wastewaters entering wastewater treatment plants are presented
for acute risk presumptions for aquatic animals; endangered species risk
presumptions for aquatic animals; and acute and endangered species risk
presumptions for aquatic plants.  Table 2 presents concentrations of
concern for acute risk presumptions for aquatic animals and the
corresponding numbers of days of exceedance for these levels of concern
based on high-end and average case scenarios.  When using the PDM option
of E-FAST 2, EPA/OPPT considers risks to be significant if the acute
toxicity value for the most sensitive freshwater fish or invertebrate
tested exceeds the concentration of concern in surface water for 4 days
or more.  Estimated concentrations of triclosan in surface water did not
exceed concentrations of concern for acute risk presumptions for aquatic
animals.

TABLE 2 – NUMBER OF DAYS EXCEEDANCE OF CONCENTRATIONS OF CONCERN FOR
ACUTE RISK PRESUMPTIONS FOR AQUATIC ANIMALS

Test Species	Measurement Endpoint (mg/L)	Concentration of Concern (ug/L)
Basis of Concentration of Concern	High-End Scenario

(# days COC exceeded)	Average Scenario (# days COC  exceeded)

Rainbow trout (Oncorhynchus mykiss)	freshwater fish acute LC50 = 0.288
144	Core data from OPP guideline study	0	0

Cladoceran (Ceriodaphnia dubia)	freshwater invertebrate acute EC50 =
0.13	65	EPA Office of Water (U.S. EPA, 2007	0	0

Waterflea (Daphnia magna)	freshwater invertebrate acute EC50 = 0.39	195
Supplemental data from OPP study that does not meet guideline
requirements	0	0



Table 3 presents concentrations of concern for endangered species risk
presumptions for aquatic animals and the corresponding numbers of days
of exceedance for these levels of concern based on high-end and average
case scenarios.  Estimated concentrations of triclosan in surface water
did not exceed concentrations of concern for endangered species risk
presumptions for aquatic animals.

TABLE 3 – NUMBER OF DAYS EXCEEDANCE OF CONCENTRATIONS OF CONCERN FOR 
ENDANGERED SPECIES RISK PRESUMPTIONS FOR AQUATIC ANIMALS

Test Species	Measurement Endpoint (mg/L)	Concentration of Concern (ug/L)
Basis of Concentration of Concern	High-End Scenario

(# days COC exceeded)	Average Scenario (# days COC  exceeded)

Rainbow trout (Oncorhynchus mykiss)	freshwater fish acute LC50 = 0.288
144	Core data from OPP guideline study	0	0

Cladoceran (Ceriodaphnia dubia)	freshwater invertebrate acute EC50 =
0.13	65	EPA Office of Water (U.S. EPA, 2007	0	0

Waterflea (Daphnia magna)	freshwater invertebrate acute EC50 = 0.39	195
Supplemental data from OPP study that does not meet guideline
requirements	0	0



Table 4 presents concentrations of concern for acute risk presumptions
for aquatic plants and the corresponding numbers of days of exceedance
for these levels of concern based on high-end and average case
scenarios.  Note that measurement endpoints based on EC05 or NOAEC that
could be used for endangered species risk presumptions for non-vascular
freshwater plants were not available.  However, a NOAEC value of 0.0125
mg/L based on core data from an OPP guideline study was available for a
representative vascular aquatic plant species, the duckweed, Lemna
gibba.  This NOAEC value corresponds to a concentration of concern for
triclosan in surface water of 12.5 ug/L.  The PDM option of the
Down-the-Drain module of E-FAST 2 predicted no exceedances of the
concentration of concern for triclosan for endangered species risk
presumptions for aquatic vascular plants..  

Although estimated concentrations of triclosan in surface water were not
predicted to exceed concentrations of concern for acute risk
presumptions for species tested to represent vascular freshwater plants,
concentrations of triclosan in surface water were predicted to exceed
concentrations of concern for acute risk presumptions for species that
represent non-vascular freshwater plants (i.e., algae).    When using
the PDM option of E-FAST 2, for the most sensitive algal species tested,
if the concentration of concern is exceeded for 4 days or less, OPPT
determines the potential for significant risk on a case-by-case basis. 
The number of days of exceedance of the concentration of concern is 1
day for blue-green algae, 5 days for green algae, and 57 days for
Chlamydomonas sp.  The concentration of concern of 0.15 ug/L for the
algal species, Chlamydomonas, that was used to run the PDM option of the
Down-the-Drain module of E-FAST 2 was based on findings of a significant
reduction of this genera of algae based on an evaluation of the effects
of triclosan on natural freshwater algae located above and below a
wastewater treatment plant (Wilson et al. 2003).  Although this
evaluation is considered supplemental data, it indicates the need for
additional investigation of shifts in algal communities, reductions in
biomass, and effects on higher trophic levels (Wilson et al. 2003). 
Data on the high toxicity of triclosan to different types of algae and
on concentrations of triclosan measured in surface waters indicate that
the presence of triclosan in surface water at levels of concern to algae
may have the potential to affect the structure and function of algal
communities in freshwater stream ecosystems, particularly immediately
downstream of effluents from wastewater treatment facilities that treat
household wastewaters.  Significant adverse effects to aquatic algae,
which are primary producers in aquatic ecosystems, might potentially
impair or destroy the balance of aquatic ecosystems.  

TABLE 4 – NUMBER OF DAYS EXCEEDANCE OF CONCENTRATIONS OF CONCERN FOR 
ACUTE RISK PRESUMPTIONS FOR AQUATIC PLANTS

Test Species	Measurement Endpoint (mg/L)	Concentration of Concern (ug/L)
Basis of Concentration of Concern	High-End Scenario

(# days COC exceeded)	Average Scenario (# days COC  exceeded)

Chlamydomonas sp.	Concentration in freshwater that caused a significant
reduction in this species is 0.00015 	0.15	Supplemental data (Wilson et
al. 2003)	57	6

Green algae (Scenedesmus subspicatus)	Non-vascular aquatic plant EC50 =
0.0007	0.7	EPA Office of Water (U.S. EPA 2007)	5	<1

Blue-green cyanobacteria (Anabaena flos-aquae)	Non-vascular aquatic
plant EC50 = 0.0012	1.2	Core data from OPP guideline study	1	0

Duckweed (Lemna gibba)	Vascular aquatic plant NOAEC = 0.0125	12.5	Core
data from OPP guideline study	0	0

	

 As discussed in the revised triclosan environmental fate chapter, only
acute concentrations of concern were evaluated for aquatic organisms
since acceptable chronic aquatic data are not available.  However,
considering the low probability of triclosan being released into
household wastewater and surface waters, EPA also concludes that chronic
aquatic risks are unlikely from consumer uses of triclosan-treated
plastic and textile items.

 As discussed in the revised triclosan environmental fate chapter, only
acute concentrations of concern were evaluated for aquatic organisms
since acceptable chronic aquatic data are not available.  However,
considering the low probability of triclosan being released into
household wastewater and surface waters, EPA also concludes that chronic
aquatic risks are unlikely from consumer uses of triclosan-treated
plastic and textile items.

  EPA assumes that leaching values for plastic are of the same magnitude
as for textile products.  Note that the Agency used the 0.55 % leaching
value in its evaluation for children who may mouth (incidental oral
ingestion) plastic items (e.g., toys).

 The Agency is making this statement because published literature
indicates that triclosan and triclosan transformation products are being
detected in various environmental components and there are outstanding
environmental modeling and monitoring data.   (Also, see revised
triclosan environmental fate chapter).

 NOTE:  Confidential Business Information (CBI) has been removed from
this document.

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