### Page 2 of 16 (wheelchairs, metal bed frame s, exteriors of toilets, cuntertops, metal surfaces, imaging equipment surfaces, metal, glass, acrylic, and porcelain) in hospitals, restrooms, schools, offices, gyms, and homes. Also, Mint -A- Kleen ® 

### a ready

- to -use liquid product containing chlorhexidine gl uconate was registered in 2010 for cleaning and co ntrol of microbial contamination in dental

unit waterlines

.

There are three active ingredients in the chlorhexidine d erivatives c ase 3038; however, one of these active ingredients, chlorhexidine dihydrochloride, does not have active registered products. This chemical is not being supported and is not addressed in this registration review.

The chlorhexidine diacetate and chlorhexidine digluconate are the only active ingredients in the case with active products. For chlorhexidine diacetate a Reregistration Eligibility Decision (RED) was issued by EPA in September 1996 but no RED was issued by EPA for chlorhexidine

di gluconate.

Table 1. Registered Active Products of Chlorhexidine diacetate

Registration # Reg istration Name Company Name Formulation Type % of Active Ingredient

1117-30 Fort Dodge Nolvasan

Solution Fort Dodge Animal

Health Soluble

Concentrate 2

1117-48 Fort Dodge Nolvasan S Fort Dodge Animal

Health Soluble

Concentrate 2

1117-62 Chlorhexidine Di acetate Fort Dodge Animal

Health Technical 99.3

3573-74 Cougar The Procter & Gamble Company Soluble

Concentrate 0.01

3573-94 Chlor hexidine Diacetate The Procter & Gamble Company Technical 99.3



### Table 2. Registered Active Product of Chlorhexidine digluc onate

Registration # Registration

Name Company Name Formulation Type % of Active Ingredient

70467-3 BioSURF Micrylium

Laboratories Liquid Spray 0.2

85298-2 Mint -A- Kleen ® Anodia Systems Ready

- to

- use Liquid 0.12



### Use Patterns

EPA Reg. No.1117-30

Nolvasa n® Solution

Ch1orhexidine diacetate

### Page 3 of 16 Scented Disinfectant

Bactericide Virucide For Animal Premises Use Only Active Ingredient: 1,1’- Hexamethylenebis -5- (p -chlorophenyl) biguanide) diacetate 2% For cleaning, disinfection, deodorizing inanimate surfaces

For d isinfection of veterinary or farm premises For use in federally inspected meat, poultry, rabbit and egg establishments For dipping teats as an aid in controlling bacteria that causes mastitis. For disinfection of inanimate objects to aid in control of bacteria and viruses

EPA Reg. No.1117-48

Nolvasan® S

Chlorhexidine diacetate

Scented Disinfectant

Bactericide Virucide For Animal Premises Use Only Active Ingredient: 1,1’- Hexamethylenebis [5

- (p -chlorophenyl) biguanide] diacetate 2% For cleaning, disinfection , deodorizing

For disinfection of veterinary or farm premises For disinfection of inanimate objects to aid in control of bacteria and viruses

EPA Reg. No.1117-62

Chiorhexidine Diacetate Technical 99.3% This is a manufacturing use product for the formulation of indoor use antimicrobial hard surface disinfectant products.

EPA Reg. No. 3573-74 Cougar Active Ingredients: Didecyl Dimethyl Ammonium Chloride 0.03%

Chlorhexidine Diacetate 0.01%

Sanitizer: For use on hard non-porous floors. Sanitizing Cleaner

. Wi th Cougar Antibacterial solution, 99.9% of the bacteria* on floors are eliminated/killed.

All In -One mopping system.

Antibacterial Cleaner Cleans and kills/eliminates/removes 99.9% of bacteria* on dining area/cafeteria floors.

Cleans and kills/eliminates 9 9.9% of bacteria* on public/school floors. Cleans, and removes bacteria*

Cleans and removes household bacteria*

Cleans and Sanitizes.

Cleans and sanitizes floors wall

- to

- wall.

For use on all washable floors For use on/Great for vinyl glazed ceramic laminat e, and finished wood floor surfaces.

### Page 4 of 16 For use on/Great for vinyl, glazed ceramic sealed marble laminate and finished wood floors. For vinyl, glazed ceramic, laminate, and finished wood floors. Great for! For Use on finished floors/glazed ceramic tile/vinyl surfaces. Kills 99.9% of bacteria* and (helps) eliminate(s) odors (with fresh scent). Kills 99.9% of bacteria* and (helps) eliminate(s) odors in the air (with fresh scent). Kills and, prevents the spread of 99.9% of Enterobacter aerogenes/E. aerogenes on t reated surfaces. 

### Kills and, prevents the spread of 99.9% of Staphylococcus aureus/S. aureus on treated surfaces.

Kills/Eliminates/Removes 99.9% Ente robacter aerogenes/E. aerogenes

Kills/Eliminates/Removes 99.9% of bacteria*

Kills/Eliminates/Removes 99.9% o f bacteria* on public/guest/school floors Kills/Eliminatès/Removes 99.9% of bactéria* on floor/public restroom/lobby floors

Kills/Eliminates/Removes 99.9% of household bacteria*

Kills Eliminates/Removes 99.9% Staphylococcus aureus/S. aureus

* Effective ag ainst/k llls/99.9% of Staphylococcus aureus and Enterobacter aerogenes.

EPA Reg. No. 3573-94

Chlorhexidine Diacetate Technical 99.3% This product is a manufacturing use product for the formulation of indoor use antimicrobial hard surface disinfectant products. This product is a manufacture use product for formulation use only.

EPA Reg. No. 70467-3

BioSURF Active Ingredients

Ethanol 70.5% Chlorhexidine gluconate 0.2%

Tuberculocidal Canine Parvovirucidal Pseudomonacidal

Hospital Hard Surface Disinfectant BioSURF is a ready to use hard surface disinfectant for nonporous surfaces • One Step. For use on hard, non-porous imaging equipment surfaces Restrooms • Schools • The Office •The Gym •At Home.

BioSURF Can be used on countertops metal surfaces and toilet ex teriors. May be used on wheelchairs, metal bed f rames and exteriors of toilets. Bio SURF may be used on nonporous hard surfaces (imaging equipment, metal, glass, acrylic, and porcelain).

EPA Reg. No. 85298-2

MINT -A- KLEEN ®

Ready

- to -use Liquid 

### Active Ingredient Chlorhexidine digluconate 0.12%

Dental Unit Waterline Cleaner For the cleaning and co ntrol of microbial contamination in den tal unit waterlines. For use in any

dental unit. Ready to Use. Do Not Dilute.

### Page 5 of 16 Science Findings

The Agency has conducted a rev iew of the available product chemistry, environmental fate, and ecotoxicity data for c hlorhexidine diacetate and chlorhexidine digluconate. The findings are summarized below.

All product chemistry data requirements have been satisfied for the active ingr edient s chlorhexidine diacetate and c hlorhexidine digluconate.

Table 3. Chemical Identity

Chlorhexidine diacetate C hlorhexidine di gluconate

Chemical

Name 1,1'

- hexamethylene bis [5

- (p

- chlorophenyl) biguanide] D iacetate

2,4,11,13

- Tetraazatetradecanediim idamide, N,N''

- bis(4

- chlorophenyl)

- 3,12

- diimino

- , diacetate 1,1'

- Hexamethylene bis(5

- (4

- chlorophenyl) biguanide) digluconate

2,4,11,13

- Tetraazatetradecanediimidamide, N,N"

- bis(4

- chlorophenyl)

- 3,12

- diimino, di -D- gluconate

Common

Name Chlorhexidine diace tate Chlorhexidine digluconate

Synonyms Chlorhexidine acetate Chlorhexidine gluconate

Trade

Name s Nolvasan, Arlacide A Bactigras , Hibitane

acetate, Chlorhexidine acetate technical Hibitane chlorhexidine gluconate

Molecular Weight 625.55 g/mol 897.8 g/ mol

PC Code 045502 045504

CAS No. 56

- 95

- 1 18472

- 51

- 0

Molecular

Formula C 22 H 30 Cl 2 N 10 · 2(C 2 H 4 O 2 ) C 22 H 30 Cl 2 N 10 · 2(C 6 H 12 O 7 )

Molecular

Structure:



### Chlorhexidine diacetate C hlorhexidine di gluconate

### Page 6 of 16 Table 4 . Product Chemistry Data Summary of Chlorhexidine diacetate and Chlorhexidine digluconat e
Guideline

No. Physical and Chemical Properties Chlorhexidine diacetate

99.9% Chlorhexidine digluconate 20% w/v Aqueous solution (Technical)

830.1550 Product identity and composition Refer to Table 3

. Refer to Table 3

.

830.1600 Description of materi als used to produce the product CBI CBI

830.1620 Description of production process CBI CBI

830.1650 Description of formulation process CBI CBI

830.1670 Discussion of formation of impurities CBI CBI

830.1700 Preliminary analysis CBI CBI

830.1750 Certified limits CBI CBI

830.1800 Enforcement analytical

method Polarographic methods Polarographic methods

830.1900 Submittal of samples N / A NA

830.6302 Color White or almost white Clear, water w hite to amber l iquid

830.6303 Physical State Powdered Solid Microcrystalline powder Liquid

830.6304 Odor Odorless or almost odorless Mild, practically odorless

Mild medicinal odor

It has a Bitter taste

830.6313 Stability to sunlight,

normal and elevated

temperature,
metals/metal ions Stable under ambient wa rehouse

conditions to moisture and simulated sunlight. Stability data at temperatures of

25 

### ° C and 30°C over a 48 mo nth period demonstrated that

chl orhexidine acetate is stable in both amber glass bottles and in tin plate lever lid containers for a period

o f 48 months. Chlorhexidine acetate technical is transported in plastic bags inside fiberboard tin plate lever

lid containers. The product is stable.

830.6314 Oxidation/Reduction:

Chemical Incompatibility Chlorhexidine acetate is compatible

with an oxidiz ing agent (potassium permanganate), a reducing agent (zinc powder), water and carbon dioxide. No significant increase in temperature was observed with any mixture tested although in the case of potassium permanganate, a rise in temperature of approximately 4°C was detected upon initial mixing but

this returned to ambient within 1 hr. N/A

830.6315 Flammability N/A Flash point > 100 °C N/A Flash point: 376.7 °C

830.6316 Explodability N/A N/A

### Page 7 of 16 Guideline

No. Physical and Chemical Properties Chlorhexidine diacetate

99.9% Chlorhexidine digluconate 20% w/v Aqueous solution (Technical)

830.6317 Storage Stability Stability data at temperatures of 25° and 30°C over a 48 month period

demonstrated that chlorhexidine acetate is stable in both amber glass bottles and in tin plate lever lid containers for a period of 48 months Shelf

- life is three years at 2

- 8°C. Storage Temp: 2

- 8°C

.

830.6319 Miscibility N/A Miscible with water

830.6320 Corrosion

Characteristics Stability studies have shown that the physical condition of the product in tin plate lever lid containers is satisfactory. There is no evidence to suggest that product pack interaction would be a pr oblem. Non

- corrosive in presence of glass.

830.6321 Dielectric breakdown voltage N/A N/A

830.7000 pH 6.8 (in 1% solution)

7 in solution 20% solution (w/v) 6.0

– 6.8 (1% soln/water): Neutral.

830.7050 UV/Visible Absorption Not Reported

. Not Reported

. 8 30.7100 Viscosity N/A NR

830.7200 Melting point 158.7 oC N/A

830.7220 Boiling point N/A The lowest known value is 100°C (212°F) (Water).

830.7300 Density Density: 1.2 g /cm 3 Sp Gr: 1.06 at 20°C Density: 1.06 g/mL at 25°C (lit.)

830.7370 Dissociation Cons tant N/A pKa = 10.78 in water 1

830.7550 Partition coefficient ( n

octanol/water) N/A Octanol/acetate buffer (pH 5) Log

D=0.08 N/A

- 0.33 (EPI Suite)

830.7840 Solubility in water Solubilizes 1.9 g/100 mL (20 oC) Soluble in water

. Easily soluble in cold w ater. Fully miscible

. Miscible with water

. 830.xxxx Solubility in organic

solvents Ethanol.....

. 6.7 gm/100 ml Glycerol.... slightly soluble Propane..... slightly soluble Soluble in ethanol & acetone.

Soluble in polar solvents such as lower alcohols, gly cols and other polyols.

830.7950 Vapor pressure N/A

Chlorhexidine acetate is a solid

which melts above 100 °C, vapor pressure is therefore not applicable. The highest known v alue is 17.535 mm of Hg (@ 20°C (Water).

N/A = Not applicable; TGAI=Technical Gr ade Active Ingredient; CBI= Confidential Business Information

### Page 8 of 16 Environmental Fate Summary

No definitive environmental fate assessment can be made because no data have been submitted regarding the chemical degradation, microbial metabolism or mobility of

chlorhexidine derivatives

.

The Agency did not conduct an environmental fate assessment for chlorhexidine

derivatives because of lack of data . However, the Agency needs to conduct an environmental

fate assessment for disinfectant/sanitizers used in animal premises that may potentially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic environments. For this assessment the Agency anticipates needing those data outlined on

page 11 of this document.

Water Qua lity

Chlorhexidine derivatives are not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=88

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

d erivatives , based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id =885&p_pollutant_group_name=PESTICIDES . 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 pe sticide. 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 Managemen t Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1- sop.pdf ), in order to ensure they can be used quantitatively or qualitatively in pesticide risk

assessments.

Ecological Effects Summary

The registrant has submitted ecological effects studies for both terrestrial and aquatic animals. These data are adequate to provide the Agency with sufficient information to determine appropriate label precau tions, and may be seen in Tables 5 and 6 below.

a. Toxicity to Terrestrial Animals

(1) Birds, Acute and Subacute

Chlorhexidine diacetate is slightly toxic to practically nontoxic to avian species on an acute oral and subacute dietary basis.

Chlorhexidi ne digluconate is slightly toxic to avian species on an acute oral and subacute dietary basis.

### Page 9 of 16 b. Toxicity to Aquatic Animals

(1) Freshwater Fish

Chlorhexidine diacetate is moderately toxic to cold water fish and highly toxic to

warm water fish.

Chlorh exidine digluconate is highly toxic to both cold and warm water fish.

(2) Freshwater Invertebrates

Chlorhexidine diacetate is highly toxic to aquatic invertebrates.

Chlorhexidine digluconate is highly toxic to aquatic invertebrates.

c. Toxicity to Aqua tic Plants

(1 ) Freshwater Algae

No algal toxicity data have been submitted

. For the ecological risk assessment, including an endangered species assessment for all uses, the Agency anticipates needing the algal toxicity data outlined on page 11 of this document.

Ecotoxicity data are adequate to provide the Agency with sufficient information to determine appropriate label precautions.

Table 5. Ecotoxicity Data Summary for Chlorhexidine diacetate

GUIDE

LINE COMMON

NAME TAXONOMIC

NAME TEST

TYPE %

AI STUDY

TIME DOSE

TYPE TOXI

CITY TOX

LEVEL NOEL STUDY

STATUS TOX

CATEGORY MRID

Avian Acute Oral Toxicity

850.2100 Bobwhite quail Colinus virginianus O 100 14 D LD 50 2013 MGK 292 Acceptable Slightly

toxic 42197501

Avian Subacute Dietary Toxicity

850.2200 Bo bwhite quail Colinus virginianus D 100 8 D LC 50 >5620 PPM 1780 Acceptable Practically

non toxic 42197502

850.2200 Mallard

duck Anas platyrhynchos D 100 8D LC 50 >5620 PPM 5620 Acceptable Practically

non toxic 42197503

Freshwater Fish Acute Toxicity

850.10 75 Rainbow

trout Oncorhynchus mykiss S 100 96 hr LC 50 1871 PPB 900 Acceptable Moderately

toxic 42197504

850.1075 Bluegill

sunfish Lepomis

macrochirus S 100 96 hr LC 50 600 PPB 300 Acceptable H ighly toxic 42197505

Freshwater Invertebrate Acute Toxicity

8 50.1010 Water

flea Daphnia

magna S 100 48 hr EC 50 63 PPB 32 Acceptable Very highly

toxic 42197506

### Page 10 of 16 Table 6. Ecotoxicity Data Summary for Chlorhexidine digluconate

GUIDE

LINE COMMON

NAME TAXONOMIC

NAME TEST

TYPE %

AI STUDY

TIME DOSE

TYPE TOXI

CITY TOX

LE VEL NOEL STUDY

STATUS TOX

CATEGORY MRID

Avian Acute Oral Toxicity

850.2100 Mallard

duck Anas platyrhynchos O 20.0

Tech 14 D LD 50 >2510

Eq to 502 mg/kg ai MGK Suppl emental Slightly

toxic 00030213

Avian Subacute Dietary Toxicity

850.2200 Mallard

duck Anas platyrhynchos D 20.0

Tech 8 D LC 50 >10000

Eq to 2000 ppm ai PPM 4640 Supplemental Slightly

toxic 124744

850.2200 Bobwhite quail Colinus virginianus D 20.0

Tech 8D LC 50 >10000

Eq to 2000 ppm ai PPM >10000 Supplemental Slightly

toxic 126034

Freshwate r Fish Acute Toxicity

850.1075 Rainbow

trout Oncorhynchus mykiss S 20.0

Tech 96 hr LC 50 2.3 PPM 1.21 Acceptable H ighly toxic 00124743

850.1075 Bluegill

sunfish Lepomis

macrochirus S 20.0

Tech 96 hr LC 50 0.51 PPM 0.21 Acceptable H ighly toxic 00124743

Freshwater Invertebrate Acute Toxicity

850.1010 Water

flea Daphnia

magna S 20.0

Tech 48 hr EC 50 0.42 Eq to 84 ppb PPM Acceptable Very highly

toxic 241539

045504



### Adverse Ecological Incidents

There are no reported incidents in the Agency' s Ecological Incident I nform ation System (EII S) regarding chlorhexidine derivatives. The absence of documented incidents does not necessarily mean that such incidents did not occur.

Ecological Effects Risk Assessment

An ecological risk assessment was not conducted on the chlorhexidine derivatives 

### ’s

disinfectant/sanitizer use 

### patterns described in this document. Chlorhexidine derivatives 

### uses in animal premises and dental unit water lines 

### that have potential for environmental exposure are

down the drain disinfectant/s anitizer 

### discharges. The Agency needs to conduct environmental fate and ecological risk assessments for disinfectant/sanitizers used in animal premises and dental

unit water lines 

### that potentially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic environments. For this ecological risk assessment, including an endangered species assessment for all uses, the Agency anticipates needing the algal toxicity data outlined on page 11 of this document.

The Agency has not conducted a risk assessment that supports a complete endangered species determination. The ecological risk assessment planned during registration review will allow the Agency to determine whether chlorhexidine derivatives 

### ’s use has “no effect or “may affect” federally listed threatened or endangered species (listed species) or their designed critical habitats. When an assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency will cons ult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Services (the Services), as appropriate.

### Page 11 of 16 Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work

Environmental fate and ecological risk assessments have not been condu cted for chlorhexidine derivatives. The Agency needs to conduct environmental fate and ecological risk

assessments for disinfectant/sanitizers used in animal premises and dental unit water lines that may potentially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic environments. Therefore, the Agency anticipates needing the proposed

environmental fate 

### and ecotoxicity data for chlorhexidine derivatives and/or any of its major degradation products that are of potential concern for all registered uses of chlorhexidine derivatives. The following environmental fate 

### and ecotoxicity data are needed to conduct an environmental fate and ecological risk assessment:



### • The Agency anticipates needing the following data to conduct a complete

environmental fate assessmen t for animal premises and dental unit water lines 

### uses :

o (GLN 835.2120) Hydrolysis;

o (GLN 835.2240) Photodegradation in water;

o (GLN 8 50.6800) Modified Activated Sludge Respiration Inhibition;

o (GLN 835.1110) A ctivat ed Sludge Sorption I sotherm; and

o (GLN 835.3110) R eady Biodegradability.

**•** The Agency anticipates needing the following data in order to conduct a complete ecological risk assessment, including an endangered species assessment:

o (GLN 850.5400) algal toxicity (Tier II) using freshwater green alga, Selenastrum capricornutum.

### Page 12 of 16 

## Appendix A. Environmental Fate Guideline Study Justifications

Guideline Number: 835.2120 Study Title: Hydrolysis
Practical Utility of the Data 1) What is the value of the study?

D ata characterizing the rate of hydrolytic degradation of chlorhexidine derivatives and/or the formation and decline of degradates is important in determining the persistence and concentrations of chlorhexidine

derivatives and potential degradates over time in various aquatic environments. For outdoor uses,

chlorhexidine derivatives can reach surface water through direct contact or discharge to WWTPs. Chlorhexidine derivatives may also reach surface water or groundwater through run-off or leaching

processe s. The Agency will evaluate the potential risks of concern.

2) How would the data be used? The data would establish the significance of chemical hydrolysis as a route for degradation and identify, if possible, the hydrolytic transformation products forme d that may adversely affect non

- target organisms and may contaminate water and food source of aquatic organisms. The data would also help establish the hydrolytic half

- life of chlorhexidine derivatives and possibly degradates, and assist in developing a

d egradation pathway.

3) How could the data affect the risk assessment? The results of hydrolysis data would indicate if chlorhexidine derivatives is persistent or if it degrades into other products that may adversely affect nontarget organisms and may cont aminate their food and water and possibly soil.

4) What is triggering the need for this data? Hydrolysis data is needed to conduct the fate assessment to support material preservatives uses for

chlorhexidine derivatives

.



### Guideline Number: 835.2240 Study Title: Photodegradation in water
Practical Utility of the Data 1) What is the value of the study? Biocides introduced into aqueous systems in the environment can undergo photolytic transformation by sunlight. Results from the photolysis study will indi cate the stability and persistence of chlorhexidine

derivatives and potential degradates in an aquatic environment when exposed to sunlight. The Agency will evaluate the potential risks of concern.

2) How would the data be used?

The data would establish the significance of chemical photolysis as a route for degradation and identify, if possible, the photolytic degradation products formed that may adversely affect non- target organisms and may contaminate water and food source of aquatic organisms. The dat a would also help establish the photolytic half

- life of chlorhexidine derivatives and possibly degradates, and assist in developing a degradation pathway.

3) How could the data affect the risk assessment? The results of photolysis data would indicate if chlorhexidine derivatives are persistent or if they degrade

into other chemical products that may adversely affect nontarget organisms by contaminating their food supply. The results of the photolysis data would expand the understanding of the results of t he hydrolysis data since environmental aquatic conditions usually involve exposure to sunlight.

### Page 13 of 16 Guideline Number: 835.2240 Study Title: Photodegradation in water 4) What is triggering the need for this data? Aqueous photodegradation data is needed to conduct the fate assessment to support material preservative

uses for chlorhexidine derivatives

.



### Guideline Number: 850.6800 Study Title: Modified Activated Sludge Respiration Inhibition
Rationale for Requiring the Data The modified activated sludge, respiration inhibition test is needed to identify whether this pestic ide could harm microorganisms found in biological wastewater treatment systems. The Agency will utilize

these data to conduct the environmental fate assessment and to determining the potential impact of this

chemical on waste water treatment plants (WWTPs ) via effects on WWTP microbes. This test is also necessary to enable EPA to establish correct concentrations for use in the ready biodegradability test. Practical Utility of the Data

1. How will the data be used? The data will be used to assess exposu re and risk to non -target endangered and non- endangered species. Exposure data are integral part s of the risk equation for determining the impact of pesticides to beneficial

non- target organisms through direct exposure from their food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions are needed. The study will identify the inhibitory effect of this chemical on the treatment plant’s microorganisms’ respiration at a particular c oncentration and will identify the EC 50 , the effective

concentration at which the respiratory rate is reduced by 50%. EPA will use the data to determine the

chemical’s potential to directly harm the non

- target organisms and/or the microbial treatment proc esses present in a WWTP. The data will also determine suitable non -inhibitory concentrations to be used in biodegradability tests.

2. How could the data impact the Agency’s future decision -making? If the data show a high degree of respiratory inhibition, higher- tiered environmental fate studies may be required and the risk a ssessments for this chemical m ay need to be revised to address the impact of the potential risk. The risk assessment may result in the Agency requiring label restrictions that would be necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA (e.g., changes t o the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not likely to jeopardize the continued existence of any endangered or threatened species or result in

the destruction or adverse modification of critical habitat” and to use the best scientific data available” in carrying out this obligation. The data EPA intends to call in are necessary to inform the determination required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the species or its critical habitat. Absent this data EPA may not be able to conclude tha t this pesticide will not harm endangered species and may therefore need to consider other limitations on the use of the pesticide in order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in use restrictions which are unnecessarily severe.

### Page 14 of 16 Guideline Number: 835.1110 Study Title: Activated Sludge Sorption Isotherm
Rationale for Requiring the Dat a Data from this study are needed to determine the sorption potential of activated sludge for the removal of specific chemical compounds in biological wastewater treatment plants (WWTPs). If the chemical is not sorbed or biodegraded

, then it would pass through a biological treatment system unaffected, potentially contaminating surface and drinking waters where it may then have the potential to adversely

affect nontarget organisms. EPA needs activated sludge sorption study data to assess the distribution of

the antimicrobial chemical among the solid, aqueous, and vapor phases of WWTPs. Specifically, this study identifies those chemicals which sorb to sludge biomass. Practical Utility of the Data

1. How will the data be used?

The data will be used to ass ess exposure and risk to non -target endangered and non- endangered species. Exposure data are integral part s of the risk equation for determining the impact of pesticides to beneficial nontarget organisms through direct exposure from their food sources and habitat

.

In addition, t he data will be used to determine whether or not additional studies and/or label restrictions are

needed. If the data indicate that the chemical does not sorb to sludge and instead partition s more readily to

water

, then the chemic al has the potential to pass through the WWTP and therefore could be discharged in to the aquatic environment. This determination could trigger further data requirements to assess the chemical’s impact upon release.

2. How could the data impact the Agen cy’s future decision -making? If the data show that the chemical negatively impacts the aquatic environment or the effectiveness of the WWTP, then the risk a ssessments for this chemical may need to be revised to reflect the magnitude of potential risk deriv ed from the new data. The risk assessment may result in the Agency requiring label restrictions that would be necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA (e.g., changes to the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not likely to jeopardize the continued existence of any endangered or threatened species or result in

the destruction or adverse modification of critical habitat” and to use the best scientific data available” in carrying out this obligation. The data EPA intends to call in are necessary to inform the determination required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not harm endangered species and may therefore need to consider other limitations on the use of the pesticide in

order to fulfi ll the Agency’s statutory obligations under the ESA. The lack of these data will limit the flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in use restrictions which are unnecessarily severe.

### Page 15 of 16 Gu ideline Number: 835.3110 Study Title: Ready Biodegradability
Rationale for Requiring the Data For antimicrobial chemicals that go down

- the

- drain and reach a WWTP, as part of its screening

- level environmental fate assessment, EPA will analyze the potent ial impact of the antimicrobial chemical on the microorganisms in the biological treatment processes of a WWTP. Biodegradation is an important environmental pathway in which the antimicrobial is broken down by bacteria. This study supplies information on the rate of breakdown and the completeness of the degradation to carbon dioxide and water. A ready biodegradability study would allow the Agency to determine whether the chemical achieves ‘‘pass levels’’ for ready biodegradability (e.g., 70% removal of dissolved organic carbon). Practical Utility of the Data

1. How will the data be used? The data will be used to assess exposure and risk to non-target endangered and non- endangered species. Exposure data are integral part s of the risk equation for determin ing the impact of pesticides to beneficial

non- target organisms through direct exposure from their food sources and habitat.

In addition, the data will be used to determine whether or not additional studies and/or label restrictions

are needed. If the chemical does not achieve a ‘‘pass level’’ for ready biodegradability, then the Agency would determine that the chemical has the potential to pass through the WWTP and therefore may be discharged in to the aquatic environment potentially resulting in exposur e to non

- target species. This determination would trigger further data requirements to assess the chemical’s impact on the aquatic environment upon release.

2. How could the data impact the Agency’s future decision -making?

If the chemical is found to b e readily biodegraded, then impact on WWTP would be identified as minimal and most likely no further studies or label restrictions would be required. If a low rate of biodegradability is identified, then higher

- tiered environmental fate studies may be tri ggered and the risk assessments for this chemical may need to be revised to reflect the magnitude of potential risk derived from the chemical’s lack of biodegradability. The risk assessment may result in the Agency requiring label restrictions that

would be necessary for the products to meet the “no unreasonable adverse effects” requirements of FIFRA (e.g., changes t o the directions for disposal).

In addition, EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not likely to jeopardize the continued existence of any endangered or threatened species or result in

the destruction or adverse modification of critical habitat” and to use the best scientific data available” in carrying out this obligation. The data EPA intends to call in are necessary to inform the determination required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the species or its critical habitat. Absent this data EPA may not be able to conclude tha t this pesticide will not harm endangered species and may therefore need to consider other limitations on the use of the pesticide in order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the flexibility that the Agency and registrants have in coming into compliance with the ESA and could result in use restrictions which are unnecessarily severe.

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## A ppendix B: Ecological Guideline Study Justifications

Guideline Number: 850.5400 Study Title: Algal toxicity (T ier II) using freshwater green alga, Selenastrum Capricornutum Practical Utility of the Data 1) What is the value of the study? As part of an initial risk assessment, one indicator plant species is tested for phytotoxicity. This study would allow the Ag ency to categorize chlorhexidine derivatives as toxic or non- toxic to plants. If toxic, additional higher tier plant tests would be needed. An endangered species assessment for endangered or threatened plants is not possible without this study.

2) How w ould the data be used? This study would be used to evaluate the toxicity of chlorhexidine derivatives to non- target plants in terrestrial and aquatic ecosystems.

3) How could the d ata affect the risk assessment?

Adverse effects to non

- target plants in terrestrial and aquatic ecosystems may result in mitigation to protect species at risk. Mitigation might include reduced label dosages, neutralization of effluents prior to discharge into water, restrictions on use in sensitive ecosystems or where endangered species are present, or other mitigation measures.

4) What is triggering the need for this data? Increased concern from state regulators and the public to evaluate impacts on WWTP operations, endangered species, and persistence in the environment, since initial registration, have triggered the need for this study. Green algae are critical to ecosyste m health and productivity.