### Page 2 of 27 Executive Summary

Sodium is a broad spectrum antimicrobial compound. Sodium omadine is registered for

use as a materi al preservative in metalworking cutting fluids, adhesives, caulks, paints (in

- can), janitorial products (in

- container), and hides/leather / leather products (surfaces). Sodium

omadine was first registered in the United States in 1968 for use as a material preservative. A Reregistration Eligibility Decision (RED) was issued by EPA for sodium omadine in January

1996 . Currently there are six companies that have twelve active registratio ns. One of these products is registered as a technical with an active ingredient declaration of 40%, and one is registered as an intermediate manufacturing use product with active ingredient declarations of 41.57%. The remaining ten products are end

- use products with active ingredient declarations of 1.2 to 41%; these products consist of soluble ready

- to

- use solutions and a flowable soluble

concentrate. All product chemistry data requirements have been satisfied for this active ingredient.

At the time of the RED, risk assessments were not conducted for industrial microbiocides unless products had a once

- through cooling water system use. To regulate these industrial microbiocide uses and associated risks to the aquatic environment, the Agenc y required that labels for sodium omadine products that require discharges to aquatic environments comply with a National Pollutant Discharge Elimination System (NPDES) permit. As part of the registration review process, risk assessments for material pres ervatives such as the metalworking cutting

fluids will be conducted.

To conduct these assessments, t he Agency data base for evaluating the environmental fate and transport of sodium omadine is incomplete

. Because of the down drain antimicrobial uses, th e Agency anticipates needing activated sludge sorption isotherm

, activated sludge respiration inhibition, one of four waste biodegradability tests ( ready biodegradability, porous
pot test, or one of two simulation tests) for material preservatives that pot entially pass through waste water treatment plants (WWTPs) and may be discharged into terrestrial and aquatic

environments. Additionally, an aquatic photolysis study is needed

. Based on environmental fate information currently inhouse, s odium omadine i s essentially stable with half

- li fe of at least 23 days, but no acceptable photolysis in water data ha s been submitted.

Sodium omadine is moderately toxic to avian species on an acute oral basis and slightly toxic to avian species on a subacute dietary ba sis; slightly toxic to mammals on an acute oral basis; and very highly toxic to freshwater fish and aquatic invertebrates. For the ecological risk assessment, including an endangered species assessment for all uses, t he Agency anticipates needing algal to xicity data , a freshwater fish early life stage study, an invertebrate life cycle study

, and a resubmittal of a rainbow trout acute toxicity study. From the information available

coldwater rainbow trout are more acutely sensitive to sodium omadine than bl ue gill sunfish, but

th e degree is unknown because the study did not provide a definitive LC 50 

### value for the rainbow trout ( i.e , 96

- h LC 50 

### < 7.3 ppb sodium omadine). To conduct a quantitative risk assessment a definitive acute toxicity value for this more sensitive species is needed.

### Page 3 of 27 Introduction

Sodium omadine was first registered in the United States in 1968 for use as a m aterial

preser vative

. Twelve products containing sodium omadine are currently registered which are

listed in Table 1. T hey are used in metalworking cutting fluids, cooling and lubricating fluids, adhesives, caulks, patching compounds, sealants, pastes and grouts, paints (in

- can), inks,

sponges, jani torial products (in

- container), hides / le ather / leather products (surfaces) , aqueous analytical and diagnostic reagents u sed in chemical and clinical analysis, aqueous synthetic fiber lubricating (spin finishes), carrageenan based gels used in solid air fresheners, dry wall and gypsum, pearlite, plaster

- like, mineral used in manufacture of tile, chrome or vegetable tanned

le ather, for the dry film preservation of natural, and synthetic adhesives, latexes, urethane foams, caulks, patching compounds, sealants, architectural paints, industrial paints and coatings (including wood coatings), glues, in

- can preservation of la tex emu lsions used in adhesives, laundry rinse additives, laundry detergents, carpet cleaners, s urface cleaners, floor cleaners, pigment slurries, building materials such as joint cements and concrete additives, materials in the textile, paper, polishes waxes, pr otein solutions, ceramic glazes, fire extinguishing materials, cleaning solutions and detergents as a materials preservative. A Reregistration Eligibility

Decisi on (RED) was issued by EPA for s odium omadine in January 199 6 1



### .

Table 1. Registere d Product s of Sodium o madine

Registration
# Registration

Name Company

Name Formulation Type % of Active Ingredient

1258

- 843 Sodium Omadine 40% Aqueous Solution Arch Chemicals, Inc. Ready

- to

- Use

Solution 40

1258

- 990 Triadine 10 Arch Chemicals, Inc. Ready

- to

- Use
Solution 6.56

1258

- 1205 Triadine 20 Industrial

Microbiostat Arch Chemicals, Inc. Ready

- to

- Use
Solution 3.69

1258

- 1213 Sodium Omadine 10% Aqueous Solution Arch Chemicals, Inc. Ready

- to

- Use
Solution 10

1258

- 1238 Sodium Omadine

- E 10% Aqueous Solution Arch Chemicals, Inc. Soluble

Concentrate 10

10350

- 56 Sodium Pyrithione 3M Soluble

Concentrate 41

39967

- 26 Preventol WB Plus Lanxess Corporation Soluble

Concentrate 1.2

43813

- 48 Sodium Pyrion 40% Aqueous Solution Janssen PMP Soluble

Concentrate 40

43813

- 49 Sodium Pyrion 40% MP Janssen PMP Technical
Chemical 40

1 http://www.epa.gov/oppsrrd1/REDs/0209.pdf

### Page 4 of 27 Registration
# Registration

Name Company

Name Formulation Type % of Active Ingredient

63898

- 2 Tomicide S API Corporation Soluble

Concentrate 41

87772

- 1 Phicide Sodium Manufacturing Concentrate Dublinchem, Inc Formulation

Intermediate 41.57

87772

- 2 Phicide Sodium (Sodium Pyrithione 41% Aqueous Solution) Dublinchem, Inc Soluble

Concentrate 41



### The Agency has conducted a review of the available product chemistry, environmental fate, and ecotoxicity data for sodium o madine

. The primary source of information for this

assessment was the 1996 Sodium o madine RED. The findings are summarized below.

The physical and chemical properties of the 90% TGAI and 40% TGAI Sodium o madine

are shown below

A. Product Chemistry Summary of the Sodium omadine (Min. 90% TGAI Solid)

Common Name: Sodium o madine Sodium pyrithione

Chemical Name: Sodium omadine exists as a mixture of two

tautomeric forms:

1

- hydroxy

- 2(1H)

- pyridinethione, sodium salt and

2

- pyridinethi o

- 1

- oxide, sodium salt

.

2

- (1H)

- Pyridinethione, 1

- hydroxy

- , sodium salt

2

- Mercaptopyridine

- N

- oxide sodium salt

Trade and Other Names: Omadine ® sodium,

sodium 2

- pyridinethiol 1

- oxide,

sodium 1

- hydroxypyridine

- 2

- thione,

sodium 2

- mercaptopyridine

- N

- oxide

OPP Chemical Code: 088004

CAS Registry Number: 15922

- 78

- 8

Case No. : 0209

Chemical Family: Mercaptan Pyridine

### Page 5 of 27 Molecular Formula: C 5 

### H 4 

### N O SNa ; C 5 

### H 5 

### NOS.Na

Molecular weight: 149.16 g/mole

Molecular Structure:

Color: Technical sodium omadine is an off

- white solid powder

.

Physical State: Solid, powder

Odor: None to Mild odor.

Stability: Sodium omadine is stable at 100 ° C for 120 hours, and at pH's above 7 but is in equilibrium with omadine acid below pH 7. The recommended pH range is 7

- 12.

Will gradually degrade when exposed to light and should be packaged in brown or opaque container.

Oxidation/Reduction: Not an oxidizer or reducing agent . Do not contain oxidizing or reducing agents

.

Flammability Not required because the product does not contain combustible liquids

.

Explodability: Not explosive. Contains no explosive ingredients

. Storage Stability: Stable: 3 month sample shows no degradation

. Accelerated storage stability (thermal stability) shows no degradation

.

Stability: I ts assay will remain unchanged after 2 years' storage while avoiding light.

### Page 6 of 27 97% Powder pH 7.14: The results revealed that there were no significant changes in the physical and chemical

p roperties viz, appearance (color, physical state, odo r), pH and active ingred ient of the test substance after the accelerated storage for a period of 14 days at 54 ± 2°C.

Miscibility: Not required because the product is not an emulsifiable liquid and is not to be diluted with petroleum solvents.

Corrosion Characteristics: Not corrosive to packaging material . No corrosion of

metals

.

Dielectric breakdown voltage: 

### Not applicable for products not intended to be used around electrical equipment

.

pH: 10% in water 9.4

– 9.8 ; 2% in water: 8.7 ; The mean pH of sodium pyrithione solid 97% was

7.11 ± 0.03 at 21.1 °C.

UV/Visible absorption: The UV

- Visible absorption spectra of sodium pyrithione solid 97% were determined at three different pH levels [viz., pH

- 7.15 (neutral solution), pH

- 1.97 (acidic solution) and pH 12.86 (basic solutio n)].

The UV absorbance was 0

. 255, 0.688 and 1.350 at wavelength 331.0, 281.0, and 243

. 0 nm respectively for neutral solution and the molar absorption coefficient ( ε 

### ) was 3990.61, 10766.82 and 21126 76, respectively

.

The UV absorbance was 0

. 287

, 0

. 587 and 0

. 733 at

wav elength 331.0, 271.0 and 218

. 0 nm respectively for acidic solution and the molar absorption coefficient ( ε 

### )

4681 .89, 9575.86 and 11957.5 9 , respectively.

The UV absorbance was 0.229, 0.683 and 1 .444 at wavelength 332.0, 282.0 and 243.0 nm, res pectively for basic solution and the molar absorption coefficient ( ε 

### ) was 3735.73, 11141.92 and 23556.28, respectively. Viscosity: Not applicable for solid products

.

Melting point: 252

- 257°C

, Decomposes.

Boiling Point: Not applicable for solids

.

Density: Bulk Density: 0.5 g/ml

### Page 7 of 27 The mean density of sodium pynthione solid 97% was

0. 7043 ± 0.0013 g/cm3 at 20 ± 1 °C.

Dissociation Constant (pKa) : 

### The mean dissociation constant of sodium pyrithione solid

97% was 5.61 ± 0.21 at 20°C.

Particle Size : 6 5 to less than 25 μ (90% Na om adine )

.

Log K o/w 

### : Not applicable.

- 2.72 (Source: EPI Suite)

.

Solubilit ies : The average value was 54.74 w/w % which is equivalent to 120.95 g per 100 ml of H 2 

### O.

The solubility of sodium pyrithione solid 97% in buffer water (pH 5.01) was> 1000 g/L at 20 ± 1 °C.

The solubility of sodium pyrithione solid 97% in buffer water (pH 7.03) was> 1000 g/L. at 20 ± 1 °C.

The solubility of sodium pyrithione solid 97% in buff er water ( pH 9.05) was> 1000 g/L at 20 ± 1 °C.

Vapor Pressure: 7 x 10 - 8 

### mm Hg at 2 2 ° C

. 2. 23 x 10 - 10 

### mm Hg (Source: EPI Suite)

.

Henry's Law Constant: 2.47 E

- 008 atm

- m 3 

### /mole at 25 ° C ( Source: EPI Suite)

.



### Enf orcement Analytical

Method: Iodometric determination

Ultravoilet Determination

Titrimetric Method Amperometric Titration

Product Chemistry Summary of Sodium omadine (40% of TGAI Solution)

Color: Clear a mber; dark or light yellow or amber transparent liquid

.

Physical State: Clear liquid

.

Odor: None to Mild odor

.

Stability: Stable under normal conditions. Sodium omadine is unaffected by pH values above 7. Below 7, it is in equilibrium with omadine acid.

### Page 8 of 27 Will gradually degrade when exposed to light and should be packaged in brown or op aque container.

Oxidation/Reduction: Not an oxidizer or reducing agent. Do not contain oxidizing or reducing agents. No temperature change was recorded during 24 hours and no corrosion or pitting was detected.

Flammability Not required because the product does not contain combustible liquids

.

Explodability: Not explosive. Contains no explosive ingredients.

Storage Stability: There were no significant chemical changes in any of the samples over the period of the study of 12 months. There

were no visible changes in the appearance of the products over the period of the study.

Miscibility: Not required because the product is not an emulsifiable liquid and is not to be diluted with petroleum solvents.

Corrosion Characteristics: Not corrosive to packaging material. No corrosion of

metals.

There was no evidence of corrosion to any of the

containers. The sodium omadine 40% solution remained a clear, amber

- colored liquid in all containers.

Dielectric breakdown voltage: 

### Not applicable for products not intended to be used around electrical equipment

.

pH: 8.5

- 10.5 or 9.8

.

UV/Visible absorption: The UV

- Visible absorption spectra of sodium pyrithione solid 97% were determined at three different pH levels [viz., pH

- 7.15 (neutral solution), pH

- 1.97 (a cidic solution) and pH 12.86 (basic solution)].

The UV absorbance was 0.255, 0.688 and 1.350 at wavelength 331.0, 281.0, and 243.0 nm respectively for neutral solution and the molar absorption coefficient ( ε ) was 3990.61, 10766.82 and 21126 76, respective ly.

The UV absorbance was 0.287, 0.587 and 0.733 at wavelength 331.0, 271.0 and 218.0 nm respectively for

### Page 9 of 27 acidic solution and the molar absorption coefficient ( ε ) 4681.89, 9575.86 and 11957.59, respectively.

The UV absorbance was 0.229, 0.683 and 1.444 a t wavelength 332.0, 282.0 and 243.0 nm, respectively for basic solution and the molar absorption coefficient ( ε ) was 3735.73, 11141.92 and 23556.28, respectively.

Viscosity: The viscosity of the five batches ranged from 9.94 to 11.89 cps. The average valu e was 10.98 cps.

Melting point: Not applicable

.

Boiling Point: 105oC

– 109oC

.

Density: 10.2 lb/gal; Sp

. Gr

. at 25oC 1.22 (1.19

- 1.26 g/ml)

.

Dissociation Constant (pKa): 4.56 + 0.01 at 21.9°C

.

Log K o/w 

### : Not applicable.

Solubilities: Soluble.

Vapor Pressure: 19 mm Hg @ 25 ° C

.

Enforcement Analytical

Method: Iodometric determination

Ultravoilet Determination

Titrimetric Method Amperometric Titration

All product chemistry data requirements have been satisfied for the active ingredient sodium o madine (S ource: MRID s 00159036, 00159037, 00159038, 0015903 9, 40170101, 40974101, and 41189901 ; 471266

- 4,

- 5,

- 6,

- 9,

- 10,

- 12,

- 14,

- 15,

- 16,

448431

- 01 & 449976

- 01 )

.

### Page 10 of 27 B. Environmental Fate Summary

No environmental fate assessment was performed for sodiu m omadine at the time of the registration. Available environmental fate guideline studies and the results are summarized

below.

The Agency's conclusions for the degradation, studies are as follows.

In the hydrolysis study, measurements at each combinati on of concentration (10 mg/l or 100 mg/l), temperature (5 ° C or 40 ° C), and pH (4, 7, or 10), indicate that a half

- life of 23 days

was obtained at 40 ° C, pH 10, and 10 mg/l concentration. At other levels of concentration, temperature, and pH, sodium omadi ne hydrolyzed more slowly, or was stable to hydrolysis. Hydrolytic products were more readily formed at an alkaline pH than at neutral and acidic pH. It has been hypothesized that omadine disulfide is formed by oxidation at all pH's, and at alkaline

condi tions omadine disulfide reacts with hydroxide ions to form omadine sulfinic acid (MRID 40383001).

There is no record of receipt of acceptable data on photodegradation in water, and the registrant should submit these data to support the continued use of this product. However, the RED dated January 1996 concluded that photolysis is probably a more important route of dissipation than hydrolysis, based on photolytic half

- lives of 40

- 126 minutes at a concentration of 100 mg/l and irradiation by natural sunli ght. Raw data were allegedly provided to the Agency by Olin Corporation, but the methodology was not documented in sufficient detail and decline of specific degradates was not addressed. Therefore, an additional st udy will need to be submitted.

The Agenc y did not conduct an environmental fate assessment for sodium omadine

because of lack of data. However, the Agency needs to conduct an environmental fate assessment for material preservatives (including sodium omadine) that may potentially pass through wa ste 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 1 5 of this document

.

Inform ation and data from other omadine (pyrithione) complexes will also be used to provide a complete characterization of the fate of sodium omadine in the environment. S odium

omadine would dissociate into sodium and omadine ions. The omadine ions would be expected to possible form metal complexes like zi nc and copper omadine (also referred to as zinc or copper pyrthione)

. Degradates that are expected are those c ommon to zinc and copper pyrthiones which are non

- chelated pyrithione and pyridine degradates :

**•** Pyrithione disulfide

**•** Pyrithione sulfinic acid

**•** Pyri thione sulfonic acid

**•** Pyrithione thiosulfonic acid

**•** Pyridine disulfide

**•** Pyridine sulfinic acid

**•** Pyridine sulfonic acid

**•** 2

- mercaptopyridine/2

- mercaptopyrine

- N

- oxide (mixed disulfides)

### Page 11 of 27 Water Quality

Sodium omadine is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act, based on information provided at the Agency’s National Pesticides Cause of Impairment of Waters website (searched April 7, 2011) 2



### . In addition, no Total Maximum Daily Loads (TMDL) have been developed for sodium omadine, based on information provided at the Agency’s National Pesticide TMDL web site (searched April 7, 2011) 3 

### . More information on impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/

. The Agency invites submission of water qu ality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of

the OPP Standard Operating Procedure: Inclusion of Impa ired Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/s ession1

- sop.pdf ), in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

C. Ecological Effects Summary

No ecological risk assessment was performed for sodium omadine at the time of the registration. Available ecotoxicity guideline studies for sodium omadine and the results are

summarized in Table 2. Potential data which may be used in the assessment inclu des information from metal omadine complexes and degradates; these data are summarized in Tables 3 and 4, respectively. Before use in the assessment this information will be normalized to the number of moles of omadine present. For evaluating effects to the estuarine environment, the metal complex data will be used to estimate toxicity from discharge of sodium omadine. The Agency's conclusions for the terrestrial and aquatic effects studies for sodium omadine are as follows.

a. Toxicity to Terrestrial Animals

Birds, Acute and Subacute

Sodium omadine is moderately toxic to avian species on an acute oral basis and slightly toxic to avian species on subacute dietary basis.

b. Toxicity to Mammals

Acute Oral: Sodium omadine is slightly toxic to mammals o n an acute oral basis.

2

- generation rat reproduction study: Slightly decreased number of pups per litter born in both generations (possibly a consequence of reduced mating success due

to hind limb atrophy), delayed development in pups from both generation s

2

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

3
http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_ group_name=PESTICIDES

### Page 12 of 27 (including open ears and eyes and startle response), and decreased pup body weight and weight gain in both sexes.

c. Toxicity to Aquatic Animals

Freshwater Fish and Invertebrates Sodium omadine was found to be very highly toxic to rainbow trout, bluegill sunfish and daphnia. From the information available coldwater rainbow trout are more acutely sensitive to sodium omadine than bluegill sunfish and daphnia, but the degree is unknown because the study did not provide a definitive LC 50 

### value

for th e rainbow trout ( i.e , 96

- h LC 50 

### < 7.3 ppb sodium omadine).

d. Toxicity to Aquatic Plants

Freshwater Algae

No algal toxicity data have been submitted. For the ecological risk assessment, including an endangered species assessment for all uses, t he Agenc y anticipates needing the algal toxicity data outlined on page 1 3 of this document

.

Table 2 . Ecotoxicity Data Summary for Sodium omadine

MRID

No. GUIDE

LINE COMMON

NAME TAXONOMIC

NAME TEST

TYPE %

AI STUDY

TIME DOSE TYPE TOXI CITY TOX

LEVEL NOEL STUDY
STATUS TOX

CATEGORY

00103228 850.1010 (72

- 2) Water flea Daphnia

magna S 40 .0 48 hr EC 50 0.022 (9.2 μ g ai/l) ppm 0.011 Acceptable Very highly

toxic

40494501

Lot No.

F113C 850.1075 (72

- 1d) Rainbow

trout Oncorhynchus mykiss S 41.9 96 hr LC 50 <0.076 ( < 7.3 μ g

ai/l) ppm N.R. Supplemental Very highly

toxic

40358501 850.1075 (72

- 1b) Bluegill

sunfish Lepomis

macrochirus S 41.9 96 hr LC 50 8.1 (8100 μ g

ai/l) ppm 0.89 Acceptable Very highly

toxic

40363401 850.2100 (71

- 1) Bobwhite quail Colinus virginianus O 41.9 14 D LD 50 441 (185 mg /kg

ai ) m g / k g

bw <150 Acceptable Moderately

toxic

00073656 850.2200 (71

- 2a) Bobwhite quail Colinus virginianus D 40 .0 8 D LC 50 3246 (1300 mg ai/l) p pm

diet 1000 Acceptable Slightly toxic

00073657 850.2200 (71

- 2b) Mallard

duck Anas platyrhynchos D 40 .0 8 D LC 50 9119 (3650 mg ai/l) p pm

diet 1000 Acceptable Slightly toxic

40247801 81

- 1 Rat

--------- ----- 40 .0

----- LD 50 1500 (M+F) m g/kg

bw ------ Acceptable III Slightly toxic

### Page 13 of 27 MRID

No. GUIDE

LINE COMMON

NAME TAXONOMIC

NAME TEST

TYPE %

AI STUDY

TIME DOSE TYPE TOXI CITY TOX

LEVEL NOEL STUDY
STATUS TOX

CATEGORY

41097201 83

- 4 Rat

-------- ----- 40.2

----- Parental

LOEL

Reproductive

LEL 1.5

3.5 mg/kg

bw/day

mg/kg

bw/day 0.5

1.5 Acceptable

Based on increased incidence of histologic atrophy in the upper

hindlimb skeletal muscles (reduction in fiber diameter) in F1 females (3/25), F0 males (7/23), and F1 males (9/25). Additional parental effects seen at 3.5 mg/kg/day included increased histologic atrophy in the upper hindlimb skeletal muscles in F0 females (19/24), and F1 females (20/23); and significantly decreased body weight in F0 and F1 females.

Based on slightly decreased number of pups per litter born in both generations (possibly a consequence of reduced mating

success due to hind limb atrophy), delayed development in pups from both generations (including open ears and eyes and startle response), and decreased pup body weight and weight gain in both sexes.
Test Type

— O: oral; D: dietary; F: flow

- through; S: Static ; Tox Level

— mg / k g

- bw : milligrams per kilogram

- body weight; ppm: parts per million (equivalent to milligrams per kilogram

- diet (mg/kg

- diet) for dietary exposure and milligrams per liter (mg/L) for aquatic exposures) Categories of acute toxicity for aquatic organisms (U.S. EPA, 2004) based on EC 50 /LC 50 (mg/L): < 0. 1 very highly toxic; 0.1

- 1 highly toxic;

>1

- 10 moderately toxic; >10

- 100 slightly toxic; >100 practically nontoxic. Categories of acute toxicity to terrestrial animals, avian and mammalian (U.S. EP A, 2004). LC 50 (ppm): < 50 very highly toxic; 50

- 500 highly toxic; 501

– 1000 moderately toxic; 1001

- 5000 slightly toxic; >5000 practically non

- toxic. LD50 (mg/kg bw): < 10 very highly toxic; 10

- 50 highly toxic; 51

- 500 moderately toxic; 501

- 2000 slig htly toxic; >2000 practically non

- toxic.



### Table 3

. Aquatic Ecotoxicity Data Summary for Zinc and Copper O madine

Test Species Test material
(% ai) 96

- h LC50 (μg ai/L) (95% CI) Toxicity Category MRID No./ Study Status

Rainbow trout zinc pyrithione (97.8) 3.6 (3.0

- 4.3) very highly

toxic 438646

- 13 / Acceptable

Fathead minnow zinc pyrithione (97.8) 2.6 (2.1

- 3.2) very highly

toxic 438646

- 06 / Acceptable

copper pyrithione (94.7) 4.3 (3.7

- 5.0) very highly

toxic 457743

- 18 / Acceptable

Waterflea copper pyrithione (94.7) 10.1 (7.9

- 13) very highly toxic 457743

- 16 / Acceptable

zinc pyrithione (97.8) 8.2 (5.2

- 25.8) very highly toxic 438646

- 04 / Acceptable

### Page 14 of 27 Sheepshead
minnow zinc pyrithione (97.8) 400 (200

- 590) highly toxic 438646

- 05 / Acceptable

Mysid shrimp zinc pyrithione (97.8) 4.7 (4.0

- 5.5) very highly

toxic 438646

- 07 / Acceptable

Eastern oyster copper pyrithione (94.7) 9.2 (0

- ∞) very highly

toxic 457743

- 17 / Acceptable

zinc pyrithione (97.8) 22.0 (18.9

- 27.3) very highly

toxic 438646

- 08 / Acceptable



### Table 4

. Acute Toxicity of Two Pyrithione Degradates to Fish and Aquatic Invertebrates Exposed in the Water Column

Test Species Test material
(% a.i. ) 96

- h LC 50 (μg a.i./L )
(95% CI) Toxicity
Category MRID No./ Study Status

Rainbow

trout pyridine sulfonic acid (98) 57,100 (48,300

- 69,800) slightly toxic 438646

- 27 / Acceptable

pyrithione sulfonic acid (98.5) 92,300 (73,600

- 124,000) slightly toxic 438646

- 16 / Acceptable

pyridine sulfonic acid (98) 68,500 (55,200

- 85,000) slightly toxic 438646

- 21 / Acceptable

pyrithione sulfonic acid (98.5) 58,800 (48,700

- 71,000) slightly toxic 438646

- 18 / Acceptable

Waterflea pyridine sulfonic acid (98) >122,000 practically

nontoxic 438646

- 22 / Acceptable

pyrithione sulfonic acid (98.5) >127,000 practically

nontoxic 438646

- 19 / Acceptable

Sheepshead
minnow pyridine sulfonic acid (98) >127,000 practically

nontoxic 438646

- 23 / Acceptable

pyrithione sulfonic acid (98.5) >137,000 practically

nontoxic 438646

- 17 / Acceptable

Mysid shrimp pyridine sulfonic acid (98) 71,000 (62,800

- 81,100) slightly toxic 438646

- 26 / Acceptable

pyrithione sulfonic acid (98.5) 70,300 (61,600

- 81,600) slightly toxic 438646

- 20 / Acceptable

### Page 15 of 27 Eastern
oyster pyridine sulfonic acid (98) 85.600 (73,300

- 102,500) slightly toxic 438646

- 24 / Acceptable

pyrithione sulfonic acid (98.5) 96,200 (89,313

- 104,560) slightly toxic 438646

- 15 / Acceptable



### Adverse Ecological Incidents

There are no reported incidents in the Agency's Ecological Incident Information System (EIIS) regarding sodium omadine. 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 sodium omadine’s use patterns

described in this document. Sodium omadine uses that have potential for environmental exposure are material preservatives discharges. The Agency needs to conduct environmental fate and ecological risk assessments for material preservatives that potentially pass through waste

water treatmen t plants (WWTPs) and may be discharged into terrestrial and aquatic

environments. For this ecological risk assessment, including an endangered species assessment for all uses, t he Agency anticipates needing a rainbow trout acute toxicity study, algal toxi city

data

, a freshwater fish early life stage study, an invertebrate life cycle study outlined on page 1 6

of this document

.

The Agency has not conducted a risk assessment for sodium omadine that supports a complete endangered species effects determinati on. The ecological risk assessment planned during registration review will allow the Agency to determine whether sodium omadine’s use has “no effect or “may affect” federally listed threatened or endangered species (listed species) or their designed criti cal habitats. When an assessment concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries Services (the Services), as appropriate.

Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work

Environmental fate and ecological risk assessments have not been conducted for sodium

omadine . The Agency needs to conduct environmental fate and ecological risk assessment s for material preservatives that 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 sodium omadine and/or any of its major degradation products that are of potential concern for all registered uses of sodium

omadine . The following environmental fate and ecotoxicity data are needed to conduct an environmental fate and ecological risk assessment:

### Page 16 of 27 **•** The Agency anticipates needing the following data to conduct a complete

environmental fate assessment for material preservative use s :

o Activated Sludge Sorption Isotherm ( GLN 835.1110);

o Photodegradation in water (GLN 8 35 .2240 ) ; and

o Ready biodegradability ( OCSPP 835.3110) , Porous Pot Test ( OCSPP 835.3220), or Simulation Tests to Assess the Biodegradability of Chemicals Discharged to

Wastewater ( OCSPP 835.3280), or Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units ( OCSPP 835.3240) 4



### .

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

o Rainbow trout acute toxicity test (GLN 850.1075);

o Algal toxicity (Tier II) using freshwater green alga, Selenastrum capricornutum (GLN 850.5400) (If the IC 50 

### is equal to or less than 1000 ppb, data for three additional algal species and an aquatic non

- vascular plant test would also be required);

o Freshwater invertebrate life cycl e study (GLN 850.1300);

o Fish early life stage test with rainbow trout (the most sensitive fish species) (GLN 850.1400);

o Activated Sludge Respiration Inhibition ( GLN 850.6800 or OECD 209 ) ;

Facility Emissions to WWTP Modeling

For assessing the fate of sodium omadine and its major toxic degradates, emitted to receiving waters from antimicrobial uses of sodium omadine such as metalworking cutting

fluids , photographic industry the Agency anticipates using the a vailable environmental f ate
information from guideline studies for sodium omadine and information for other omadine complexes and the following emission scenarios.

**•** Potential environmental releases and associated exposures of concern for antimicrobial

uses related to metalworking fuids will be those identified in "Emission Scenario

Documents on the Use of Metalworking Fluids ", Number 2 8 of OECD Series on Emission Scenario Documents dated July 6 , 20 11;

4 The results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which of these four biodegradation tests are required. If the ASRI test EC 50 is less than or equal to 20 mg/L, then either the (i) Biodegradation in Activated Sludge Study or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge

Units or the (iii) Porous Pot Test is required. If the ASRI test EC 50 is greater than 20 mg/L, then the applicant must choose either: (i) Ready Biodegradability or (ii) Biodegradation in Activated Sludge or (iii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or (iv) the Porous Pot T est. If the antimicrobial passes the

R eady B iodegradability study, then no further testing is required. If, however, the antimicrobial fails the R eady

B iodegradability study, then the (i) Biodegradation in Activated Sludge or (ii) Simulation Test

– Aerob ic Sewage Treatment A. Activated Sludge Units, or (iii) the Porous Pot study is required.

### Page 17 of 27 **•** Potential environmental releases and associated exposures of concern for antimicrobial

uses related to a dhesive preservatives will be those identified in "Emission Scenario

Document on Adhesive Formulation ", Number 2 0 of OECD Series on Emission Scenario

Do cuments dated April 24 , 20 09;

**•** Potential environmental releases and associated exposures of concern for antimicrobial

uses related to paints and coating preservatives will be those identified in "Emission

Scenario Document on Coating Industry (Paints, Laque rs and Varnishes) ", Number 2 2 of

OECD Series on Emission Scenario Documents dated April 24 , 20 09;

**•** To estimate exposure related to releases of sodium omadine to domestic wastewater treatment plants from use s such as sodium omadine in detergents

, laundry rinses, and

cleaners the Agency will rely on the Office of Chemical Safety and Pollution Prevention (OCSPP) model, Exposure and Fate Assessment Screening Tool (E

- FAST, version 2.0, 2007, or EFAST2). From this model, the Agency will use the “Down

- th e

- Drain” (DtD) module, which is designed to evaluate releases to domestic wastewater treatment plants.

It is suitable for all the indoor sources of d

- phenothrin that could potentially be exposed through a “down

- the

- drain” scenario. The model provides scr eening level estimate concentrations of chemicals in surface water that may result from household uses and the disposal of consumer products into wastewater using a few simple input parameters (production volume and fraction of the chemical removed during wastewater treatment).

Facility information needed to estimate aquatic exposures from emissions to WWTP for each emission scenario include the following:

**•** The number of metalworking fluid sites using sodium omadine or the maximum annual production volume o f sodium omadine used for metalworking fluids in the United States and its territories;

**•** The number of adhesive industrial or manufacturing sites using sodium omadine or the maximum annual production volume of sodium omadine used in the adhesive

formulation industry in the United States and its territories;

**•** How many of each of these facilities has on

- site and/or off

- site wastewater treatment.

**•** The production volume used in detergents and cleaners.

In the absence of information on the number of these facilit ies that use sodium omadine and how many of these facilities have on

- site and/or off

- site wastewater treatment, the Agency will assume that all such facilities in the United States have the potential to use sodium

omadine.

In the absence of appropriate t est data on biodegradation during wastewater treatment, the Agency will assume that there is no removal of sodium omadine and its major toxic degradates during wastewater treatment and that the amount of sodium omadine and its major toxic degradates releas ed with the effluent from a wastewater treatment facility will be the same as the amount entering the wastewater treatment facility.

### Page 18 of 27

### Page 19 of 27 

## Appendix A. Environmental Fate Guideline Study Justifications

Study Title: Activated Sludge Sorption Isotherm

Guideline Number: 835.1110
Test Substance: TGAI Rationale for Requiring the Data 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). No data is currently available. 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 t o adversely affect non

- target 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 assess removal of the antimicrobial as a result of sorption to activated sludge. Percent removal via sorption to activated sludge and percent removal via biodegradation are used to determine overall removal of the antimicrobial during wastewater treatment. Over all removal during wastewater treatment is a key input used to determine concentrations of the antimicrobial in surface water immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide immediately downstream of was tewater treatment plants are used to assess exposure and risk to non

target endangered and non

- endangered species. Exposure data are integral parts of the risk equation for determining the impact of pesticides to beneficial nontarget organisms through dir ect 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 data indicate that the chemical does not sorb to sludge and instead partition s more readily to water and that the chemical does not biodegrade to an appreciable extent then the chemical has the potential to pass through the WWTP and therefore could be discharged to the aquatic environment. This determination could trigger further data requirements to assess the chemical’s impact upon release. If the data indicates relatively high potential to sorb to sludge, a screening assessment of potential exposure to ecological organimsm as a result of biosolids use and disposal would be perf ormed.

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

- making?

If the data show that removal of the chemical during wastewater treatment is negligible, then the risk

assessments for this chemical would reflect the magnitude of potential risk de rived from this chemical’s negligible removal . 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 destructio n 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 registrati on 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 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

### Page 20 of 27 could result in use restrictions which are u nnecessarily severe.



### Study Title: Photodegradation in water
Guideline Number: 835.2240

Test Substance: TGAI 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 indicate the stability and persistence of sodium omadine and potential degradates in an aquatic environme nt 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 deg radation products formed that may adversely affect non

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

- life of sodium omadine 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 sodium omadine is persistent or if it degrades into degradation products that may adversely affect nontarget organisms and may contaminate their food. The results of the photolysis data would expand the understanding of the results of the hydrolysis data since environmental aquatic conditions usually involve exposure to sunlight.

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 sodium omadine

.

### Page 21 of 27 Study Titles: Ready Biodegradability; Porous Pot Test; or Simulation Test

– Aerobic Sewage

Treatment: A. Activated S ludge Units; or Simulation Tests to Assess the Biodegradability of Chemicals Discharged to Wastewater (particularly Biod egradation in Activated Sludge)
Guideline Numbers: 835.3110; 835.3220; 835.3240; or 835.3280 , respectively
Test Substance: TGAI 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 potential impact of the antimicrobial chemical on the microorganisms i n the biological treatment processes of a WWTP. Biodegradation is an important environmental pathway in which the antimicrobial is broken down by bacteria. These study results supply information on the rate of biological breakdown and the completeness of t he degradation to carbon dioxide and water. A Ready Biodegradability study would allow the Agency to determine whether or not the chemical achieves ‘‘pass levels’’ for ready biodegradability (e.g., 70% removal of dissolved organic carbon). The results of t he Activated Sludge Respiration Inhibition Test (ASRI) determine which of these four biodegradation tests are required. If the ASRI test EC 50 is less than or equal to 20 mg/L, then either the (i) Biodegradation in Activated Sludge Study or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or the (iii) Porous Pot Test is required. If the ASRI test EC 50 is greater than 20 mg/L, then the applicant must choose either: (i) Ready Biodegradability or (ii) Biodegradation in

Activated Slud ge or (iii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units or (iv) the Porous Pot Test. If the antimicrobial passes the Ready Biodegradability study, then no further testing is required. If, however, the antimicrobial fails the Rea dy Biodegradability study, then the (i) Biodegradation in Activated Sludge or (ii) Simulation Test

– Aerobic Sewage Treatment: A. Activated Sludge Units, or (iii) the Porous Pot study is required. Practical Utility of the Data

1. How will the data be used? The data from a biodegradation study will be used to determine the percent removal of the antimicrobial as a result of biodegradation of the antimicrobial by activated sludge microorganisms. Percent removal via biodegradation is a key input used to determine concentrations of the antimicrobial in surface water immediately downstream of wastewater treatment plants. The concentrations of antimicrobial pesticide immediately downstream of wastewater treatment plants are used to assess exposure and risk to non

target endangered and non

- endangered species. Exposure data are integral parts 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 additio n, 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 exposure to non

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

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

- making? If the chemical is found to be readily biodegraded, then activated sludge microorganisms would be identified as highly biodegradable (90% removal via biodegradation) . This result would be used in conjunction with wastewater treatment plant influent volume and measurement endpoints for aquatic organisms to determine concentrations of antimicrobial pesticide downstream of wastewater treatment plants. If high inhibitio n of activated sludge microorganisms (i.e., EC 50 less than or equal to 20 mg/L) is determined in an activated sludge respiration inhibition test, then higher

- tiered wastewater treatment plant (WWTP) biodegradation studies and/or an activated sludge sorptio n isotherm study may be triggered. If results of higher

- tier WWTP biodegradation tests indicate low or negligible removal by biodegradation,

### Page 22 of 27 the risk assessments for this chemical would reflect the magnitude of potential risk derived from the

chemical’s l ack 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 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 fu lfill 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 23 of 27 

## Appendix B: Ecological Guideline Study Justifications

Study Title: Fish acute toxicity test using rainbow trout, the most sensitive species
Guideline Number: 850.1075
Test Substance: TGAI Rationale for Requiring the Data The available study for this species indicates it is the more sensitive species tested, however, while the value itself is the lowest fish acute value it is a nondefinitive value (i.e., 96

- hr LC 50 <7.3 ppb). The use of the bluegill definitive value (8100 ppb) available to assess risk would underestimate acute toxicity. Alternatively, use of the existing rainbow trout data would also underestimate risk. Scientifically sound
freshwater fish data for sodium omadine is necessary because freshwater fish may b e exposed based on the antimicrobial use patterns of sodium omadine . The requested data would allow EPA to soundly

estimate risks to freshwater fish , including defining an action area for endangered species

. Without these data, the Agency would use the s upplemental data which would underestimate risk to an unknown degree

.

Practical Utility of the Data

1. How will the da ta be used? These data are needed for a registration review decision and for an endangered species assessment, which will be conducted as part of that decision. The freshwater fish acute study data would allow the Agency

to analyze acute lethal effects to freshwater fish from acute exposures due to sodium omadine use. The
effects data would be used to de termine the likelihood that the acute risks can potentially impact aquatic communities, either by direct effects on fish or by indirect effects by reducing food resou rces to species that rely on fish as a food resource

.

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

- making? Risk estimates (i.e., risk quotients or concentration of concern values) cannot be evaluated without these

data. In the absence of data, acute risks to freshwater fish would use the supplemental data but this would lead to an underestimation of risk, and the degree of underestimation would be unknown. T he lack of these data will limit the flexibility the Agency and registrants have in addressing risks or having confidence in declaring no affects to non

- listed and listed species and in coming into compliance with the Endangered Species Act, and could result in use restrictions or withdrawal of uses for sodium omadine which may otherwise be avoided, or which are unnecessarily severe.

Study Title : Aquatic Invertebrate Life

- Cycle (freshwater species )
Guideline Number: 850.13 0 0
Test Substance: TGAI Rationale for Requiring the Data

No chronic life cycle toxicity data for a freshwater invertebrate species ha s been submitted for sodium omadine. Chronic aquatic invertebrate data for sodium omadine is necessary because based on sodium

omadine ’s use pattern and fate information freshwater invertebrates may be repeated ly exposed to sodium omadine and its major degradates . The requested data would allow the Agency to estimate chronic risks to freshwater invertebrates from exposure to sodium omadine , including defining an action area for endangered species

. Without thes e data, the Agency is unable to evaluate the potential chronic risks to
freshwater invertebrates associated with chronic exposure to sodium omadine

. T he Agency would have to presume chronic risk to listed and non

- listed freshwater invertebrates

, but would not be able to quantify the

### Page 24 of 27 risk.

Practical Utility of the Data

1. How will the data be used? These data are needed for a registration review decision and for an endangered species assessment, which will be conducted as part of that decision. The aquatic invertebrate life

- cycle study would allow the Agency to analyze chronic effects, including effects on reproductive success , survival and growth, to
freshwater invertebrates due to exposure to sodium omadine . The effects data would be used to d etermine the likelihood that the chronic risks can potentially impact aquatic communities, either by direct effects on invertebrates or by indirect effects on fish by reducing their food sources.

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

- making? In the absence of data, chronic risks would be presumed to freshwater invertebrates under chronic exposure

conditions. T he lack of these data will limit the flexibility the Agency and registrants have in addressing

risks to non

- listed and listed species and in coming into compliance with the Endangered Species Act, and

could result in use restrictions or withdrawal of uses for sodium omadine which may otherwise be avoided, or which are unnecessarily severe.

Study Title: Fish Early

- life Stage Toxicity Test (freshwater species) using the most sensitive species
Rainbow trout
Guideline Number: 850.1400
Test Substance: TGAI Rationale for Requiring the Data

No fish early

- life stage toxicity test for sodium omadine has been submitted. The fish early

- life stage toxicity test provides the leth al and sublethal effects of a test substance on fish species. The study is necessary for sodium omadine because the antimicrobial use patterns and environmental fate

characteri stics are expected to result in repeated exp osure of freshwater organisms. The requested data
would allow the Agency to estimate chronic risks to freshwater fish from exposure to sodium omadine

, including defining an action area for endangered species

. W ithout these data, the Agency is unable to evaluate the potential risks to freshwater fish and aquatic

- phase amphibians (for which fish serve as surrogates) associated with chronic exposure to sodium omadine

. If the test is not conducted with the

most acu tely sensitive species, an acute toxicity test for the species used in the early life stage test needs
to be conducted to allow calculation of an acute

- to

- chronic ratio for use in predicting an early life stage result for the most acutely sensitive species

. Practical Utility of the Data

1. How will the data be used? The data from the fish early life stage test will be used to estimate the chronic risks to freshwater fish and amphibians associated with chronic exposures to sodium omadine. The data will reduce uncertainties associated with pot ential risks to freshwater fish and amphibians thereby facilitating sound environmental management of natural resources, particularly, freshwater fisheries.

2. How could the data impact the Agency’s future decisi on
- making? In the absence of data, chronic risks would be presumed to freshwater fish/amphibians under chronic exposure conditions. T he lack of these data will limit the flexibility the Agency and registrants have in addressing risks to non

- listed and lis ted species and in coming into compliance with the Endangered Species Act, and could result in use restrictions or withdrawal of uses for sodium omadine which may

### Page 25 of 27 otherwise be avoided, or which are unnecessarily severe.



### Guideline Number: 850.5400 Study Title: Algal toxicity (Tier II) Test Species: green alga
, Selenastrum capricornutum (if IC 50 

### < 1000 ppb three additional species are required : one freshwater diatom species, one estuarine/marine species, and one cyanobacterium species 

### )

Test substance : TGAI 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 Agency to categorize sodium omadine as toxic or non

- toxic to plants. If toxic (IC 50 , < 1000 ppb) additional species ( one freshwater diatom species, one estuarine/marine species, and one cyanobacterium species ) would be needed. An endangered species assessment for endangered or threatened plants is not possible without this study.

2) How would the data be used? This study would be used to evaluate the toxicity of sodium omadine to non

- target plants in terrestrial and aquatic ecosystems.

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

Adverse effects to non

- ta rget 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 o r 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 ecosystem health and productivity.

Study Title: Aquatic plant growth, floating vascular species ( Lemna sp. ), Tier II
Guideline Number: 850.4 400
Test Substance: TGA I Rationale for Requiring the Data

No non

- rooted vascular aquatic plant toxicity data ha s been submitted for sodium omadine. Based on its use patterns discharge of sodium omadine and its major degradates will be discharged to 

### surface waters

. If the algal toxicity study with Selenastrum capricornutum indicates that sodium omadine is toxic to aquatic plants data with a nonvascular aquatic plant is needed to characterize risk to higher tier plants. The requested data would allo w the Agency to estimate risks to aquatic plants from exposure to sodium

omadine , including defining an action area for endangered species

.

Practical Utility of the Data

1. How will the data be used? These data are needed for a registration review decision and for an endangered species assessment, which will be conducted as part of that decision. Mats of floating non

- rooted aquatic plants provide habitat for small invertebrates, food and shelter for f ish and amphibians, and food for waterfowl and marsh birds.

### Page 26 of 27 The floating vascular aquatic plant study would allow the Agency to evaluate effects to a critical component of the structure and function of the aquatic plant community. A toxicity study on a n on

- rooted vascular aquatic plant species is used to establish a dose response relationship of sodium omadine with

effects to non

- rooted aquatic plants in terms of yield, growth rate, and area under the growth curve . The
effects data would be used to determine the likelihood that losses to non

- rooted aquatic vascular plants will occur and that such losses would indirectly lead to loss of other aquatic organisms through impacts such as loss of a food resource, habita t, or habitat quality

.

2. How could the data impact the Agency's future decision

- making? If the algal toxicity study with Selenastrum capricornutum indicates that sodium omadine is toxic to algae, in the absence of sodium omadine data with a vascular aquatic plant sodium omadine would be

assumed to be toxic

. T he lack of these data will limit the flexibility the Agency and registrants have in addressing risks to non

- listed and listed species and in coming into compliance with the Endangered Species Act, and could result in use restrictions or withdrawal of uses for sodium omadine which may otherwise be avoided, or which are unnecessarily severe.



### Study Title: Modified Activated Sludge, Respiratio n Inhibition Test for Sparingly Soluble
Chemicals or Activated Sludge Respiration Inhibition Test

Guideline Number: 850.6800 or OECD 209 , respectively
Test Substance: TGAI Rationale for Requiring the Data An activated sludge, respiration inhibition test (ASRI) is needed to identify whether this pesticide could harm activated sludge microorganisms found in biological wastewater treatment systems. The Agency will use these data to determine the potential imp act of this chemical on waste water treatment plants (WWTPs) as a result of respiration inhibition of activated sludge microorganisms. This test is also necessary to enable EPA to establish correct concentrations for use in the biodegradability test, if

th at test is determined to be adequate for assessing biodegradation potential. Furthermore, the results of the Activated Sludge Respiration Inhibition Test (ASRI) determine which biodegradation test is required.
If the ASRI test EC 50 is less than or equal to 20 mg/L, then either the Biodegradation in Activated Sludge Study or the Porous Pot Test is required. If the ASRI test EC 50 is greater than 20 mg/L, then the applicant must choose either: (i) Ready Biodegradability or (ii) Biodeg radation in Activated Sludge or the Porous Pot Test. If the antimicrobial passes the ready biodegradability study, then no further testing is required. If, however, the antimicrobial fails the ready biodegradability study, then the Biodegradation in Acti vated Sludge or the Porous Pot study is required.

### Page 27 of 27 Practical Utility of the Data

1. How will the data be used? The data will be used to assess potential adverse effects to activated sludge microorganisms. In addition,
the data will be used to determine whether or not label restrictions are needed. The study will identify the inhibitory effect of this chemical on the treatment plant’s microorganisms’ respiration at different concentrations of the test substance and will identify the EC 50 , the effective c oncentration of the test substance at which the respiration rate is 50% of that shown by the control under conditions in this guideline. The data will also determine suitable non

- inhibitory concentrations to be used in biodegradability tests.

2. How coul d the data impact the Agency’s future decision

- making? If the data indicate a high degree of activated sludge respiration inhibition, a more rigorous test for biodegradation in wastewater treatment will be required than the ready biodegradability test. Al so, if a high degree of respiration inhibition is demonstrated and biodegradation and/or sorption is indicated to be negligible, the Agency may require label restrictions or mitigation measures to insure that activated sludge microorganisms will not be adv ersely impacted.