### Docket Number EPA-HQ-OPP-2012-0809 www.regulations.gov



# Sodium Carbonate (formerly Weak Mineral Bases) Preliminary Work Plan

Registration Review: Initial Docket Case Number 4066

Approved 

## by:

Date: 

# December 2012

Je pn if e r McLain

- Acting Director Antimicrobials Division

Page 

### 1 of26

### Page 2 of 26 Sodium Carbonate (formerly Weak Mine ral Acids) Registration Review Team

Human Health & Environmental Effects Timothy Dole Jenny Tao William Hazel Jonathan Chen Srinivas Gowda Najm Shamim David Bays Pat Jennings

Risk Management Seiichi Murasaki Lance Wormell

Office of General Counsel Philip Ross

### Page 3 of 26 

## Table of Contents
1 Introduction .................................................................................................................. ........... 5
1.1 Statutory and Regulatory Authority ................................................................................. 5

1.2 Case Overview ................................................................................................................. 6

1.3 Chemical Identification and Properties ............................................................................ 7

1.4 Use/Usage Description ..................................................................................................... 8

1.4.1 Registrations ............................................................................................................. 8

1.4.2 Summary of Regist ered Uses .................................................................................... 8

1.4.3 Usage Information .................................................................................................... 9

1.5 Regulatory History ........................................................................................................... 9

1.5.1 Recent/Pending Regulatory Actions ....................................................................... 10

1.5.2 Tolerance Information ............................................................................................ 10

1.6 Incidents ..................................................................................................................... .... 10

1.6.1 Human Health ......................................................................................................... 10

1.6.2 Ecological ............................................................................................................... 10

2 Anticipated Data Needs ........................................................................................................ 10

3 Human Health Risk Assessment ........................................................................................... 10

3.1 Existing Toxicological Endpoints .................................................................................. 11

3.2 Dietary Exposure ............................................................................................................ 1 1

3.3 Occupational and Residential Exposures ....................................................................... 11

3.4 Aggregate and Cumulative Exposure ............................................................................. 11

3.4.1 Aggregate Exposures .............................................................................................. 11

3.4.2 Cumulative Exposures ............................................................................................ 11

4 Environmental Risk Assessment........................................................................................... 11

4.1 Environmental Conceptual M odel Exposure Pathways ................................................. 12

4.2 Ecological Effects Assessment ....................................................................................... 12

4.2.1 Mechanism of Action .............................................................................................. 13

4.2.2 Measures of Effect (Ecotoxicology Endpoints) ...................................................... 13

4.3 Exposure Analysis Plan .................................................................................................. 13

4.4 Effects Analysis Plan ..................................................................................................... 13

5 Endocrine Disruptor Screen ing Program (EDSP) ................................................................. 14

6 Guidance for Commenters .................................................................................................... 15

6.1 Preliminary Work Plan ................................................................................................... 15

6.1.1 Trade Irritants .......................................................................................................... 15

### Page 4 of 26 6.1.2 Water Quality .......................................................................................................... 15

6.1.3 Environmental Justice ............................................................................................. 16

6.1.4 Structure Activity Relationships ............................................................................. 17

6.1.5 Additional Information ........................................................................................... 18

7 Next Steps .................................................................................................................... ......... 18

8 References .................................................................................................................... ......... 18

Appendix A Environmental Fate ............................................................................................. 19 Appendix B Ecotoxicology Profile .......................................................................................... 22

List of Tables Table 1 - Summary of Anticipated Ri sk Assessments and Data Needs ......................................... 6 Table 2 - Anticipated Registration Review Schedule ..................................................................... 6 Table 3 - Chemical Identificat ion of Sodium Carbonate ................................................................ 7 Table 4 - Physical-Chemical and Fate Properties for Sodium Carbonate ...................................... 7 Table 5 - Summary of Sodium Ca rbonate Registered Uses ........................................................... 8 Table 6 – Existing Effects Endpoints for Ri sk Assessment of Sodium Carbonate ...................... 13 Table 7 – Aquatic Organism Sodium Ca rbonate and Bicarbonate Toxicology............................ 22

List of Figures Figure 1 Total Alkalinity in Surface Wate rs of the Contiguous United States ............................. 21

### Page 5 of 26 

## 1 Introduction

1.1 Statutory and Regulatory Authority The Food Quality Protection Act (FQPA) of 1996 mandated a regi stration review program. All pesticides distributed or sold in the United St ates generally must be registered by the U.S. Environmental Protection Agency (USEPA, EPA, or the Agency ) based on scientific data showing that they will not cause unreasonable ri sks to human health or the environment when used as directed on product labeling. The regist ration review program is intended to make sure that, as the ability to assess risk evolves and as policies and practices change, all registered pesticides continue to meet th e statutory standard of no unreas onable adverse effects to human health or the environment. Changes in science, public policy, and pesticide use practices will occur over time. Through the registration review program, the Agency periodically reevaluates pesticides to make sure that as change occurs , products in the marketpl ace can be used safely. Information on this program is provided at http://www.epa.gov/oppsrrd 1/registration_review/.

The Agency is implementing the registration revi ew program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered pesticide every 15 years to determine whether it continues to meet th e FIFRA standard for registration. The regulations governing registra tion review begin at 40 CFR 155.40. The Agency will consider benefits information and data as required by FIFRA. The public phase of registration review begins when the initial docket is opened for each case. The docket is the Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses and data or information it believes are needed to make a registrati on review decision. After reviewing and responding to comments and data received in the docke t during this initial comment period, the Agency will develop and commit to a Final Work Plan (FWP) and anticipated schedule for the Sodium Carbonate Case.

Documents associated with this registration re view can be viewed at http://www.regulations.gov in docket EPA-HQ-OPP-2012-0809. Below is a summ ary of the issues relevant to this registration review case.

### Page 6 of 26 Table 1 - Summary of Anticipated Risk Assessments and Data Needs

Risk Assessment Assessment Necessary to Support Registration Review Date of Most Recent Assessment Type of Assessment Required (New/Updated) Data Anticipated as Needed Dietary (food) No 4/2/2007 None None Dietary (drinking water) No 4/2/2007 None None Occupational No 4/2/2007 None None

Residential No 4/2/2007 None None Aggregate No 4/2/2007 None None

Cumulative No N/A None None

Tolerance Review No N/A None None Ecological No N/A None None N/A = Not applicable


### Table 2 - Anticipated Registration Review Schedule
Anticipated Activity Target Date 1 Completion Date Phase 1: Openin g the Docket Open Docket and 60-Day Comment Period for Preliminary Work Plan 2012-12 2012-12-12 Close Public Comment Period 2013-02 Phase 2: Case Development Issue Final Work Plan 2013-06 Issue Data Call-In (DCI) N/A Receive Data to be Considered in Risk Assessment N/A Open 30-Day Public Comment Period fo r Preliminary Risk Assessment(s) N/A Close Public Comment Period N/A Phase 3: Registration Review Decision and Implementation Open 60-Day Public Comment Period for Proposed Decision 2013-09 Close Public Comment Period 2013-11 Issue Final Decision 2014-03 Begin Post-Decision Follow-up 2014 Total (years) 2

1 The anticipated schedule will be revised as necessary base d, for example, on any need arising under the Endocrine Disruptor Screening Program with respect to the active ingredients in this case.



## 1.2 Case Overview Case 4066 was formerly known as the Weak Minera l Bases Case (or “Mineral Bases, Weak”) and included the chemically similar active ingredients sodium carbonate (PC Code 073506), potassium carbonate (PC Code 073504), sodi um sesquicarbonate (PC Code 073507), and calcium hydroxide (PC Code 075601). Calcium hydroxide has since been moved to Case 5104 1 

### to be assessed with the active i ngredient (a.i.) calcium oxide. Si nce sodium carbonate is the only remaining chemical in the case with registered products, the case name will be changed from "Weak Mineral Bases" to "Sodium Carbonate" to re flect that the only chem ical to be reviewed under this registration review case will be sodium carbonate. The docket for the Sodium

1 Case 5104 Calcium Hydroxide/Calcium Oxide at http ://www.regulations.gov in docket EPA-HQ -OPP-2010-0693

### Page 7 of 26 Carbonate Case (Case 4066) has been estab lished at http://www.regulations.gov in docket number EPA-HQ-OPP-2012-0809.



## 1.3 Chemical Identifica tion and Properties Table 3 presents the active ingredient to be a ssessed in Case 4066: sodium carbonate (PC Code 073506). Relevant sodium carbonate product chemistr y information is summarized in Table 4.

Table 3 - Chemical Identifica tion of Sodium Carbonate
Chemical Name Sodium Carbonate 1 Synonyms carbonic acid, disodium salt; disodium carbonate; calcined soda; washing soda; soda ash Classification Weak mineral base, Inorganic carbonate
PC Code 073506
CAS No. 497-19-8 Molecular Formula Na 2 CO 3 Molecular Weight 105.9784 g/mol
Molecular Structure:

1 Source: OECD SIDS, 2002


### Table 4 - Physical-Chemical and Fate Properties for Sodium Carbonate

OPPTS Guideline Physical and Chemical Properties Sodium Carbonate 1

830.1550 Product identity and composition Refer to Table 3

830.6302 Color White solid 830.6303 Physical State Solid, hygroscopic 830.6304 Odor Odorless

830.6313 Stability to sunlight, normal and elevated temperature, metals/metal ions Stable. Hygroscopic. Stable at room temperature in closed containers under normal storage and handling conditions.

830.7000 pH 11.6 (0.1 Molar solution); 11.5 (1% solution in water). At pH 11.6 a 1% solution of sodium carbonate is a mixture of sodium carbonate and sodium bicarbonate 830.7200 Melting point 851 °C (anhydrous) 830.7220 Boiling point 1633 °C (anhydrous) 830.7300 Density 2.54 g/cm 3 at 20 oC (anhydrous)

830.7370 Dissociation Constant The pK a of CO 3 2- is 10.33, (at a pH of 10.33, both carbonate and bicarbonate are present in equal amounts). The pK a of aqueous H 2 CO 3 (combined aqueous CO 2 and H 2 CO 3 ) is 6.3 at 25 o C and 0 ionic strength (at pH 6.3, about half the molar concentration exists as aqueous carbo nic acid and half as bicarbonate (HCO 3 - )).

830.7520 Particle size The average particle size diameter (d50) of light sodium carbonate is in the range of 90 to 150 μ m and of dense sodium carbonate is in the range of 250 to 500 μ m.

830.7550 Partition coefficient ( n -octanol/water) K ow is not determined for inorganic ionic substances
830.7840 Solubility in water 71 g/L (0 o C), 215 g/L (20 o C), 455 g/L (100 o C) 830.7950 Vapor pressure No measureable vapor pressure at room temperature

1 Source: OECD SIDS, 2002

### Page 8 of 26 

## 1.4 Use/Usage Description Products containing sodium carbona te are registered for use as a mildewcide, fungicide and fungistat in hard surface and soft fabric surface disinfectants and sanitizers, as a pre-treatment on building and construction materials and for use in mold remediation and prevention following flooding or water damage clean-up, and as an antimicrobial material preservative. Sodium carbonate is also approved as a food and non- food use inert ingredient (PC Code 873506).

1.4.1 Registrations

There are four EPA registered products that contain sodium car bonate as an active ingredient (a.i.). The percent a.i. ranges fr om 0.416 percent to 3 percent and the formulations include readyto-use solutions and liquid soluble concentrates.

1.4.2 Summary of Registered Uses

Table 5 presents a summary of the registered us es of sodium carbonate. Sodium carbonate can be applied by the following application methods: m op, wipe, spray, cold fogger, brush, roller, and immersion.

Table 5 - Summary of Sodium Carbonate Registered Uses

Use Application Method Application Rate Commercial, Industrial, Institutional, Residential a Premises b and Equipment

Hard surfaces Spray, Mop, Wipe 2.8 fl. oz. of 3.0% a.i. per gallon (area treated per gallon not stated, frequency of treatment not stated) Spray (hand, electronic, compression), Wipe, Cold fogger, Paint brush, Roller, or Immersion 0.08 – 0.16 fl. oz. 0.95% solution/ft 2 reapply weekly or if growth or odor reappears

Fabric, Upholstery, Cushions Spray (hand, electronic, compression), Wipe, Cold fogger, Paint brush, Roller, or Immersion 0.08 – 0.16 fl. oz. 0.95% solution/ft 2 reapply every 28 days or if growth or odor
reappears Food Handling/Storage Areas Premises and Equipment – Indirect Food Contact

Hard surfaces Spray, Mop, Wipe 2.8 fl. oz. of 3.0% a.i. per gallon (area treated per gallon not stated, frequency of treatment not stated) Food Handling/Storage Areas in Hospitals and Institutio ns – Direct Food Contact

Food processing equipment and food contact items Spray, Mop, Wipe 2.8 fl. oz. of 3.0% a.i. per 5 gallons (area treated per gallon not stated, frequency of treatment not stated) Medical/Dental/Veterinary Premises and Equipment

Hard surfaces Wipe 0.05%

### Page 9 of 26 Use Application Method Application Rate

Medical Instruments Immersion (10 minutes, precleaned and rinsed instruments) 0.416% solution

Material Preservatives

Building materials, pulp and paper (non-foodcontact), home furnishings, house wares (nonfood contact only), floor coverings, sporting goods, apparel, films c , industrial, electronics and computer equipment, cards, currency, toys, musical instruments, Spray, cold fogger, brush, roller, or immersion: apply until evenly wet and then allow treated surface to dry completely (may wipe dry) 0.08 – 0.16 fl. oz per square foot

Incorporation % by weight of manufactured product is not specified Mold, Mildew, Fungi Remedi ation Surface Treatment Walls, floors, building and construction materials, building contents and furnishings, interiors of airplanes, boats, trains, and vehicles [includes treatment of materials to be disposed from use sites] Spray (hand, electric or compression), Wipe: apply until evenly wet and then allow treated surface to dry completely (may wipe dry) 0.08 – 0.16 fl. oz/ft 2 0.95%, reapply weekly on hard surfaces and every 28 days for fabric if growth or odor
reappears.

a Includes garages, tool sheds
b Includes interiors of vehicles, airplanes, trains, and boats

c Film includes agricultural and mulch films and silage wraps



### 1.4.3 Usage Information

Production volume data in the EPA Section Seve n Tracking System (SSTS) for the years 2004 through 2009 indicate that no more than 150,000 k ilograms of pesticidal sodium carbonate are sold per year in the United States 2



### .



## 1.5 Regulatory History The first product containing sodium carbonate as an a.i. was registered in the United States in 1964. The Food and Drug Administration assessed the toxicity of carbonates and bicarbonates in 1975 and continues to list sodium carbonate as generally recognized as safe (GRAS) 3 

### . The Agency completed a Reregistration Eligibility Decision (RED) for S odium Carbonate; Weak Mineral Acids in 2006 4 

### . In the RED, the Agency concluded that sodium carbonate poses no risks of concern when used according to EPA-approved product labeling. 

### After the risk assessments were completed to support the RED, uses were expand ed in 2005 to include mold, mildew, and fungi remediation on hard surfaces of commercial, indust rial, institutional, and residential building and construction materials, buildi ng premises, contents and furn ishings, and pre-treatment of building and construction materials; in 2007 to include fabric surfaces; and in 2008 to include material preservative uses. When each new use was added, the Agency confirmed that the additional uses of sodium carbonate pose no risks of concern.

2 Data for the years 2010 through 2012 were not used in this estimate since data collection is still in progress.
3 21 CFR §184.1742 (2012)
4 http://www.epa.gov/opp00001/chem_search/reg_acti ons/reregistration/red_PC-073506_26-Jan-06.pdf

### Page 10 of 26 1.5.1 Recent/Pending Regulatory Actions There are no recent regulatory actions for s odium carbonate. EPA anticipates issuing the postRED product-specific data call-in (PDCI) in the near future.

1.5.2 Tolerance Information

EPA has not established a tolerance or toleranc e exemption for residues of sodium carbonate in or on food. FDA lists sodium carbonate as Generally Recognized As Safe (GRAS) when used as a direct food additive substan ce (21 CFR §184.1742); no limit is placed on the amount of sodium carbonate added to food except curre nt good manufacturing practice.



## 1.6 Incidents

1.6.1 Human Health

No sodium carbonate human poisoning incidents have been reported in OPP’s Incident Data System (IDS) between 1992 and 2012.

1.6.2 Ecological

No sodium carbonate ecological incidents resultin g from its use as a registered antimicrobial have been reported in the Agency’s Ecologica l Incident Information System (EISS, v2.10) through 2012.



## 2 Anticipated Data Needs

The Agency does not anticipate the need to requi re additional data to s upport this registration review.



## 3 Human Health Risk Assessment

The Agency does not anticipate the need to condu ct a human health risk assessment for sodium carbonate nor does the Agency expect to require additional data for use in conducting the registration review. Comprehensiv e reviews of the toxicology of sodium carbonate have been conducted by regulatory organi zations including the EPA, the FDA, and the Food and Agriculture Organization FAO) /World Health Organization (WHO). In the 2006 RED, the Agency reviewed toxicology data, which incl uded unpublished studies submitted to the Agency and published literature, and conc luded that the toxicological da tabase for sodium carbonate was sufficient for reregistration. Base d on previous reviews and the currently registered uses, the Agency believes that the toxicological inform ation of sodium carbonate is adequate for the purposes of registration review. Th ere are no endpoints of concern for oral, dermal, or inhalation exposure to sodium carbonate and no evidence of increased susceptibility in a developmental toxicity study; therefore, a quantitative human health risk assessment was not conducted for the RED and is not expected to be needed for registration review.

### Page 11 of 26 

## 3.1 Existing Toxicological Endpoints There are no toxicological endpoi nts of concern for oral, dermal , or inhalation exposure to sodium carbonate and there is no evidence of increas ed susceptibility in a developmental toxicity study.



## 3.2 Dietary Exposure

There are no toxicological endpoint s of concern for oral exposure to sodium carbonate; therefore, dietary and drinking water exposures are not expected to be assessed.



## 3.3 Occupational and Resi dential Exposures There are no toxicological endpoi nts of concern for dermal, i nhalation, and incidental oral exposures to sodium carbonate; therefore, o ccupational and residen tial exposures are not expected to be assessed.



## 3.4 Aggregate and Cumulative Exposure

3.4.1 Aggregate Exposures

There are no toxicological endpoint s of concern for oral, dermal, inhalation, and incidental oral exposures to sodium carbonate; therefore, aggregat e exposures are not exp ected to be assessed.

3.4.2 Cumulative Exposures With respect to cumulative exposure, unlike other pesticides for which EPA has followed a cumulative risk approach based on a common me chanism of toxicity, EPA has not made a common mechanism of toxicity finding as to s odium carbonate and any other substances and sodium carbonate does not appear to produce a toxic metabolite produced by other substances. For the purposes of this registration review, therefore, EPA has not assumed that sodium carbonate has a common mechanism of toxicity with other substances. For information regarding EPA’s efforts to determine which chemicals ha ve a common mechanism of toxicity and to evaluate the cumulative effect s of such chemicals, see http://www.epa.gov/pesticides/cumulative/.



## 4 Environmental Risk Assessment
The Agency does not anticipate the need to condu ct a quantitative ecological risk assessment for sodium carbonate. The hard surface and fabric san itizer, disinfectant, and fungicide use patterns of sodium carbonate are expected to result in minor or insignifi cant amounts reaching or being disposed of down-the-drain as compared to the loading of sodium and carbonates from their uses for non-antimicrobial purposes such as a water supply softener and in soaps and detergents. Therefore, these uses are not expected to result in large changes in pH or buffering capacity of surface waters. The registered materi al preservative uses are also not expected to result in any significant amounts of sodium carbonate reaching su rface waters; additionall y, the use of treated agricultural and mulch films are not expected to si gnificantly change the soil pH and alkalinity at use sites.

### Page 12 of 26 Based on the low hazard and exposure, the Agency inte nds to conclude that the registered uses of sodium carbonate will have 'no effect' (NE) on e ndangered or threatened terrestrial or aquatic species, or their designated critical habitats, as listed by the U.S. Fish and Wildlife Service (USFWS) and the National Oceanic and Atmo spheric Administration's (NOAA) National Marine Fisheries Service (NMFS) . EPA anticipates conducting no further analysis of potential risks to endangered or threaten ed species unless public comment or other submissions provide data or information that would otherwise inform the Agency's determination.



## 4.1 Environmental Conceptual Model Exposure Pathways

For hard surface disinfectant, sanitizer, and f ungicide uses of sodium carbonate, the primary release of sodium carbonate will occur from disposal of used solutions down the drain ( e.g ., mop water, medical instrument used solution). Comp ared to volumes of soda ash (sodium carbonate) consumed annually in the United States for pH a nd alkalinity adjustment in water treatment and buffering and pH balance in soaps and detergents 5 

### , input into the wastew ater treatment stream from hard surface use is not expect ed to have a significant impact.

Treated porous and semi-porous materials wi ll soak up solution, and when the solution evaporates salts will crystallize. Solid sodium carbonate has negligible vapor pressure and will not decompose, or photolyze and should esse ntially remain with treated materials in situ . Except for material preservative uses in agricultural a nd mulch films and silage wraps, uses of treated articles are not likely to be in environments where non-target organisms of concern would be exposed and releases of sodium carbonate to the environment from the use of the treated articles are expected to be negligible when compared to background. Wh ile agricultural and mulch films and silage wraps will be used outdoors where non-target orga nisms could be present, any leaching of sodium carbonate to the surrounding soil is expected to be negligible and not change the soil pH or alkalinity. To result in an unacceptable adverse change in pH 6 

### or alkalinity 7



### , significant quantities of carbonate would need to be discharge d, and such quantities are not expected for the registered uses.



## 4.2 Ecological Effects Assessment

Ecological effects data are used as measures to ev aluate the potential direct and indirect effects of sodium carbonate and its degradates to aquatic and terrestrial receptors. The registrants have not submitted any ecological effects data in s upport of registration and the ecotoxicological endpoints summarized in Table 6 are based on th e peer-reviewed literature. A more detailed description of the ecoto xicity studies is prov ided in Appendix B .

5 Reported annual U.S. consumption of soda ash from 2007 through 2011 ranged around 5 to 6 million metric tons, with water treatment use consisting of around 1-2%, and soap and detergents use consisting of approximately 10- 13% –0.55 to 0.9 million metric tons annually. http://m inerals.er.usgs.gov/minerals/pubs/commodity/soda_ash/mcs2012-sodaa.pdf.
6 The Water Quality Criterion for pH is 6.5 to 9 for freshwater and 6.5 to 8.5 for salt water. The maximum change allowed in pH for seawater is ≤ 0.2 pH units (www.epa.gov/waterscien ce/criteria/library/goldbook.pdf).
7 The Water Quality Chronic Criterion for alkalinity is a minimum of 20 mg /L as calcium carbonate except where alkalinity is naturally lower. http://minerals.er.usgs.gov/minerals/pubs/ commodity/soda_ash/mcs-2012-sodaa.pdf.

### Page 13 of 26 4.2.1 Mechanism of Action

Toxicity to sodium carbonate in animals is likely caused by disruption of the mechanisms responsible for ionic regulation, and maintena nce of acid-base balance in the blood and hemolymph, and increase of the pH (O ECD SIDS 2002; Fagar and Harper, 2012).

4.2.2 Measures of Effect (Ecotoxicology Endpoints) Available ecotoxicological endpoint s are summarized in Table 6. A more detailed description of the ecotoxicity studies ar e provided in Appendix B .

Table 6 – Existing Effects Endpoints fo r Risk Assessment of Sodium Carbonate

Receptor Group Surrogate Species Risk Scenario Toxicity Endpoint Comment Reference HCO 3 - Alkalinity as CaCO 3

Freshwater fish Rainbow trout ( Oncorhyncus mykiss ) Acute 96-hr LC 50 = 5699
ppm 96-hr LC 50 = 5699 ppm Farag and Harper, 2012 Pallid sturgeon ( Scaphirhynchus albus ) Acute 96-hr LC 50 = 831
ppm 96-hr LC 50 = 608 ppm Acceptable Farag and Harper, 2012 Chronic Data not required for Na 2 CO 3 for these uses

Freshwater invertebrates Freshwater mussel ( Lampsilis siliquoidea ) Acute 96-hr LC 50 = 844
ppm 96-hr LC 50 = 670 ppm Acceptable Farag and Harper, 2012 Chronic Data not required for registered Na 2 CO 3 uses Estuarine/ Marine fish Acute Data not required for registered Na 2 CO 3 uses Chronic Data not required for registered Na 2 CO 3 uses

Estuarine/ Marine invertebrates Shrimp Acute Data not required for registered Na 2 CO 3 uses Chronic Data not required for registered Na 2 CO 3 uses Mollusk Acute Data not required for registered Na 2 CO 3 uses

Algae Green algae Chronic (EC 50 ) Data not required for registered Na 2 CO 3 uses

Chronic (NOAEC) Data not required for registered Na 2 CO 3 uses Aquatic Vascular plants Lemna sp. Chronic Data not required for registered Na 2 CO 3 uses Birds Acute Data not required for registered Na 2 CO 3 uses

Mammals Rat Acute LD 50 = 2800 mg Na 2 CO 3 /kg-bw OECD SIDS 2002 Chronic Data not required for registered Na 2 CO 3 uses



## 4.3 Exposure Analysis Plan The Agency does not anticipate the need to furt her refine exposure from sodium carbonate uses for the registration review.



## 4.4 Effects Analysis Plan As part of the the data requi red to be submitted at the time of registration, EPA generally requires the following ecological toxicity information: one avian acute oral study, one acute freshwater fish study, one acute freshwater invertebrate study, and a green algae study.

### Page 14 of 26 Acceptable results are available for freshwater fish and invertebrate studies (Table 6 and Appendix B ). An avian study is not required for the registered uses of sodium carbonate since environmental exposure is not expected. An alga l study is not required si nce the only basis for toxicity to algae is an increase in pH from the release of sodium carbonate into the environment. This release could occur afte r down-the-drain disposal of compounds containing sodium carbonate. Because waste water is treated by water tr eatment plants before effluents are released into the environment to adjust to appropriate pH limits and diluti ons in relation to the natural pH and buffering capacity of the receiving water, adverse effects to the aquatic environment, including algae, are not expect ed to result from the use a nd disposal of sodium carbonate containing pesticidal pro ducts (OECD SIDS, 2002).



## 5 Endocrine Disruptor Screening Program (EDSP)

As required by FIFRA and FFDCA, EPA reviews num erous studies to asse ss potential adverse outcomes from exposure to chemicals. Collectiv ely, these studies includ e acute, subchronic and chronic toxicity, including asse ssments of carcinogenicity, ne urotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include e ndpoints which may be susceptible to endocrine influe nce, including effects on endocri ne target organ histopathology, organ weights, estrus cyclicity, sexual maturatio n, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess gr owth, developmental and reprod uctive effects in different taxonomic groups. A human health risk assessment identifying the most sensitive endpoints has not been conducted for sodium carbonate. As required by FFDCA section 408(p), sodium carbonate is subject to the endoc rine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whet her certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or ot her such endocrine effect s as the Administrator may designate.” The EDSP employs a two-tiered approach to making th e statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrog en, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go th rough Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stag e of the EDSP where EPA will determine which, if any, of th e Tier 2 tests are necessary base d on the available data. Tier 2 testing is designed to identify a ny adverse endocrine-related eff ects caused by the substance, and establish a dose-response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must scre en all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/dat a call-ins for the firs t group of 67 chemicals, which contains 58 pesticide activ e ingredients and nine inert i ngredients. Sodium carbonate is not among the group of 58 pesticide active ingredient s on the initial list to be screened under the EDSP. Accordingly, as part of registration revi ew, EPA will issue future EDSP orders/data callins, requiring the submissi on of EDSP screening assays for sodium carbonate.

### Page 15 of 26 For further information on the status of the ED SP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening ba ttery, please visit our website: http://www.epa.gov/endo/.



## 6 Guidance for Commenters

6.1 Preliminary Work Plan The public is invited to comment on EPA’s Preliminary Work Plan and rationale. The Agency will carefully consider all comments as well as any additional information or data provided in a timely manner prior to issuing a final work plan for the Sodium Carbonate registration review

case.

6.1.1 Trade Irritants Through the registration review process, the Ag ency intends to solicit information on trade irritants and, to the extent feas ible, take steps toward facilitating irritant resolution. The Agency will work to harmonize tolerances and international maximum residue limits (MRLs) and may modify tolerance levels to do so, when possible. Stakeholders are asked to comment on any trade irritant issues resulting fr om lack of MRLs or disparities between U.S. tolerances and MRLs in key export markets, providing as much specificity as possible re garding the nature of the concern.

6.1.2 Water Quality

Sodium carbonate is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act 8 

### . However, carbonate alkalinity, which increases when sodium carbonate is dissolved in an aqueous medium, is identified as a cause of impairment, as defined under sec tion 303(d) of the Clean Water Act, for five waterbodies: one in South Dakota and four in Florida, based on information provided at EPA’s website 9 

### . High pH was identified as a cause of impairment in 39 waterbodies: three in California, three in Louisiana, three in Massachusetts, one in Maryland, and 29 in Nebraska 9,10 

### ; pH—unidentified as high or low, is identified as th e cause of impairment in 4,050 wa terbodies. Sodium is identified as a cause of impairment, as defined under se ction 303(d) of the Clea n Water Act, in seven waterbodies: four in California, one in Connecticut, and two in Montana 9



### . Of the sodium listings according to Califor nia Regional Board 6 – Lahontan Region, the two listings for the West Fork Carson River were placed on the 303(d) list for Percent Sodium 11 

### rather than sodium but were listed as “sodium ” because it was the only choice available in the database in use at that time. Pe rcent Sodium is the ratio of sodi um ion concentration to the sum of the concentrations of calcium, magnesium a nd potassium ions. Percent Sodium is an older

8 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy .cause_detail_303d?p_cause_group_id=885 (accessed October 4, 2012)
9 http://ofmpub.epa.gov/tmdl _waters10/attains_nation_cy.cause_detail_ 303d?p_cause_group_id=1188 (accessed October 4, 2012)
10 http://ofmpub.epa.gov/tmdl _waters10/attains_impair ed_waters.control?p_cause _name=PH,%20HIGH (accessed October 4, 2012)
11 http://www.waterboards.c a.gov/lahontan/water_issues/programs/ tmdl/303d_305b/factsh eets/01425.shtml (accessed October 4, 2012)

### Page 16 of 26 irrigation water criterion and has being repl aced with a new objective “Sodium Adsorption Ratio” or SAR 12 

### . The California Regional Board recognized that in certain surface waters of the West Fork Carson River watershed where higher SAR values occur as a result of natural sources ( e.g ., geothermal), the affected water bodies or water body segments will not be considered to be in violation of the applicable SAR objective. The West Fork Carbon River listings for sodium were proposed for removal from the Section 303(d ) list under Section 4 of the Listing Policy because the new SAR objective ha s been obtained in 19 out of 19 years. Sodium in one of the Montana sites is attributed to flow and agricultural sources 13



### . In Montana, high levels of sodium bicarbonate (>1,000 mg/L) o ccur in areas resulting from wastewater disposal from coal-b ed natural gas drilling. There is neither an EPA nor State of Montana water quality criterion fo r sodium bicarbonate. Results from an effort to develop site specific criteria have recently been published (Farag and Harper, 2012).

In addition, Total Maximum Daily Loads (TMDL) have been devel oped for alkalinity addressing 25 impaired water bodies located in four states (North Carolina, Ohio, Tennessee, and Virginia), for high pH in one water body in Arizona, and for pH—unidentified as high or low for 1,819 water bodies located in 23 states 14 

### and the District of Columbia based on information provided at the website 15,16 

### . More information on impaired water bodies and TMDLs can be found at EPA’s website 17



### . The Agency invites submission of wa ter quality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of the OPP Standard Operating Procedure: Inclusi on of Impaired Water Body and Other Water Quality Data in OPP’s Registration Review Ri sk Assessment and Management Process 18 

### in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

6.1.3 Environmental Justice

EPA seeks to achieve environmenta l justice, the fair tr eatment and meaningful involvement of all people, regardless of race, color, national origi n, or income, in the deve lopment, implementation, and enforcement of environmental laws, regulati ons, and policies. To help address potential environmental justice issues, the Agency seeks information on any groups or segments of the population who, as a result of thei r location, cultural practices, or other factors, may have atypical, unusually high exposure to sodium carbonate compared to the general population. Please comment if you are aware of any sub- populations that may have atypical, unusually high exposure compared to the general population.

12 http://www.waterboards.ca.gov/rwqcb6/water_issues /programs/basin_plan/docs/na_amdts_adopted.pdf
13 http://cwaic.mt.gov/wqrep/2006/FINA L_PART_E_PUBLIC_PARTICIPATION.pdf
14 Alabama, Arizona, Colorado, Georgia, Indiana, Illinois, Kansas, Kentucky, Maryland, Missouri, Mississippi, Montana, New Hampshire, New Mexico, Nevada, Ohio, Oregon, Pennsylvania, South Carolina, Tennessee, Virginia, Washington, West Virginia
15 http://ofmpub.epa.gov/tmdl _waters10/attains_nation_cy .control?p_report_type=T#t mdl_by_pollutant (accessed October 4, 2012)
16 http://ofmpub.epa.gov/tmdl_waters10/a ttains_nation.tmdl_polluta nt_detail?p_pollutant_g roup_id=1188&p_polluta nt_group_name=PH/ACIDITY /CAUSTIC CONDITIONS ( accessed October 4, 2012)
17 http://www.epa.gov/owow/tmdl/
18 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm

### Page 17 of 26 6.1.4 Structure Activity Relationships EPA must rely upon information of appropriate qual ity and reliability for each decision made by the Agency. In the Office of Pesticide Program s (OPP), the evaluation process for a pesticide chemical traditionally begins with the applicant’ s submission of a set of studies conducted with the specific pesticide chemical of interest. The us e of the results of such testing (measured data) is a logical, scientifically rigorous proce ss that identifies the physical, chemical, and environmental fate properties of the pesticide, as well as the dose and endpoints at which an adverse effect can occur in various animal species.

Today, there is significant interest in alternat ive techniques, i.e., tech niques other than data generation that could significantly inform the Agency’s decision-making process. Recently, OPP has made increasing use of stru cture activity relationship (SAR ) as part of its regulatory decision-making process. In the SAR process, a ch emical's molecular structure is compared to that of other chemicals for which data are availabl e. These structural similarities are then used to make predictive judgments about a chemical’s physical, chemical, and biological properties. Thus, the chemical’s physical, chemical, and biol ogical properties are a f unction of (or directly related to) the chemical’s molecular structure. Quantitative SAR is referred to as QSAR. To develop a QSAR, a selected set of measured da ta on a single physical, chemical, or biological property is used to derive a model (an equatio n) to predict the valu e of that property.

Since SAR assessments and QSAR modeling are anothe r set of tools that are available to Agency scientists, OPP has begun a proce ss shift that envisions shifting from the current study-by-study approach to an approach in which the use of pr edicted data, generated us ing validated models, is considered along with information from open litera ture and studies specifically generated under Part 161 requirements. All relevant information w ould be considered as pa rt of a weight-of-theevidence evaluation.

At this time, EPA believes that for certain e ndpoints, especially physi cal/chemical and fate properties, that SAR and QSAR might be effect ively utilized to fulfill these data requirements for many antimicrobial pesticide chemicals. When considering biological prope rties, at this time, EPA believes that SAR and QSAR can be most effectively utilized in the evaluation of chemicals that exhibit lower toxicity for human health and/or ecotoxicity parameters. This is appropriate because the risk assessment for lower toxicity chemicals can be stream-lined, i.e., a screening-level assessment procedure rather than multiple tiers of assessments with progressively more data requirements.

If stakeholders believe that submission of predic ted data can fulfill one of the data needs for the Sodium Carbonate Case, then the Agency invite s submission of this information. The submitter would be expected to supply a ra tionale describing the utility of the information and provide documentation on the scientific va lidity of the information. The de termination that the predicted data fulfills the data requirement would be at the sole discretion of the Agency. Pre-submission consultation with the Agency is encouraged.

### Page 18 of 26 6.1.5 Additional Information

The Agency is interested in receiving the following information:

1. Confirmation on the following label information: A. Sites of application B. Formulations C. Application methods and equipment D. Maximum application rates E. Frequency of application, applicatio n intervals and maximum number of applications F. Geographic limitations on use 2. Use or potential use distribution 3. Use history 4. Usage/use information for non-agricultura l uses (e.g., material s preservation) 5. Typical application interval 6. State or local use restrictions 7. Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and mammalian mortalities) not alr eady reported to the Agency 8. Monitoring data



## 7 Next Steps

After the 60-day comment period closes in February 2012, the Agency will review and respond to any comments received in a timely manner, and then issue a Final Work Plan for the Sodium Carbonate Case.



## 8 References

OECD SIDS. 2002. Sodium Ca rbonate, CAS No: 497-19-8. http://www.inchem.org/documents/sids/sids/Naco.pdf

Farag, A. M. and Harper, D.D. eds. 2012 The pot ential effects of sodium bicarbonate, a major constituent of produced waters from coalbed natural gas production, on aquatic life. U.S. Geological Survey, Scientific Investig ations Report 2012-5008. Preparation in cooperation with Montana Fish, Wildlife, and Parks, U.S. Bureau of Land Management, and the U.S. Environmental Protection Agency. 101 p. http://pubs.usgs.gov/sir/2012/5008/

### Docket Number EPA-HQ-OPP-2012-0809 www.regulations.gov

Page 19 of 26 

# Appendix A Environmental Fate

The registered sodium carbonate active product is the anhydrous form (Na 2 

### CO 3 

### ), which means it contains no water of hydration. Anhydrous sodium carbonate (Na 2 

### CO 3 

### ) is an inorganic ionic substance; it is highly water sol uble and dissociates in water comp letely to form sodium ions (Na + 

### ) and carbonate ions (CO 3 -2 

### ). Sodium carbonate’s high water so lubility and negligible vapor pressure means that it will be associated pr imarily with the aquatic environment. From environmental fate perspective, photodegrad ation and biodegradation pathways are not applicable for sodium carbonate or its ions.

The carbonate incorporates into the natural organic and inorganic carbon cycle. The carbonate ions will react with water, resulting in the fo rmation of bicarbonate, carbonic acid and carbon dioxide. The chemistry of carbonate in solution is that of carbonic acid (H 2 

### CO 3 

### ) equilibrium chemistry and is based on the following three universal reactions:

CO ଶ ஼௔௥௕௢௡ ௗ௜௢௫௜ௗ௘ ሺ௔௤௨௘௢௨௦ሻ 

### ൅ H ଶ 

### O

ௐ௔௧௘௥ 

### ՞ H 2 

### CO ଷ
஼௔௥௕௢௡௜௖ ௔௖௜ௗ 

### Equation 1

H 2 

### CO ଷ
஼௔௥௕௢௡௜௖ ௔௖௜ௗ 

### ՞ H CO ଷ ି

஻௜௖௔௥௕௢௡௔௧௘ ௜௢௡ 

### ൅ H ା

ு௬ௗ௥௢௡௜௨௠ ௜௢௡ 

### Equation 2

HCO 3 ି

஻௜௖௔௥௕௢௡௔௧௘ ௜௢௡ 

### ՞ CO ଷ ଶି

஼௔௥௕௢௡௔௧௘ ௜௢௡ 

### ൅ H ା

ு௬ௗ௥௢௡௜௨௠ ௜௢௡ 

### Equation 3

The form of carbonate in soluti on depends on the pH of the aque ous solution (Farag and Harper, 2012). In a recent study, it has been shown that at a low pH (4.3), sodium carbonate mostly exists as carbonic acid (H 2 

### CO 3 

### ). Between the pH range of 4.3 to 12.3, the bicarbonate ion (HCO 3 - 

### ) is the predominate moiety form of carbonate. Arou nd pH 8.3, some carbonate also exists as the carbonate ion (CO 3 2 

### ), but it is the predominant form in the most basic range (pH 12 to 14). Carbonic acid in solution is in equili brium with dissolved carbon dioxide (CO 2 

### ). The amount of dissolved CO 2 

### is controlled by the partial pressure of CO 2 

### in the atmosphere. These equilibria are the major buffer of pH for fres hwater and saltwater systems.

In natural waters, alkalinity 19 

### of the medium is attributable primarily to the presence of HCO 3 - 

### /CO 3 2- 

### species due to the common occurrence and dissolution of car bonate rocks and CO 2 

### in the atmosphere. Other common natural components ca n contribute to alkalin ity including borate (B(OH) 4 - 

### ), hydroxide (OH - 

### ), phosphate (PO 4 3- 

### , HPO 4 2- 

### ), silicate (SiO(OH) 3 - 

### ), nitrate (NO 3 - 

### ), and conjugate bases of some organic bases of some organic acids and sulf ide. Alkalinity of the medium implies the buffering capacity of the medium. Higher buffering capacity increases the

19 Alkalinity is equal to the stoichiometric sum of bases in solution: Alkalinity Total = ቂ HCO 3 - ቃ

T +2 ቂ CO 3 2- ቃ

T + ቂ B ሺ OH ሻ 4 - ቃ

T + ቂ OH ቃ

T +2 ቂ PO 4 3- ቃ

T + ቂ HPO 4 2- ቃ

T + ሾ SiO ሺ OH ሻ ଷ ି ሿ T - ൣ H + ൧ SWS - ቂ HSO 4 - ቃ

T Brackets indicate concentration and the T subscript mean s the total concentration of the species in solution. Common natural constituents contributing to alkalinity include carbonate (HCO 3- , CO 3 2- ), borate (B(OH) 4 - ), hydroxide (OH - ), phosphate (PO 4 3- , HPO 4 2- ), silicate (SiO(OH) 3 - ), nitrate (NO 3 - ), and conjugate bases of some organic bases of some organic acids and sulfide, While a number of constituents can contribute to alkalinity, HCO 3- and CO 3 2- predominate in most natural systems.

### Page 20 of 26 capacity to resist the change in pH. This characteristic drives th e aquatic and terrestrial ecotoxic effects of sodium carbona te/sodium bicarbonate.

Bicarbonate and Alkalinity in surface waters

Bicarbonate is present univ ersally in global rivers from 20 mg /L (low level)) to 190 mg/L (high level). Based on 77 rivers in North-America, Sout h-America, Asia, Africa, Europe and Oceania, the 10th-percentile, mean, and 90th-percentile of the bicarbonate concentration were 20, 106 and 195 mg/l, respectively (UNEP, 1995 cited in OECD SIDS, 2002). A map of the alkalinity (in microequivalents per liter) of surface waters in the contiguous United St ates is provided in Figure 1.

Background concentration of sodium in surface waters (from OECD SIDS, 2002)

The sodium ion is ubiquitously pr esent in the environment and it has been measured extensively in aquatic ecosystems. Sodium and chloride concen trations in water are ti ghtly linked. They both originate from natural weathering of rock, from atmospheric transport of oceanic inputs and from a wide variety of anthropogenic sources. The natura l sodium content of freshwater ranges from 0 mg/L to over 500 mg/L. The sodium concentration was reported for a total number of 75 rivers in North and South America, Africa, Asia, Euro pe and Oceania, with a 10th percentile of 1.5 mg/l, median of 28 mg/l and 90th percentile of 68 mg/l (UNEP, 1995). Seawater contains generally about 10,500 mg/L of sodium.Page21of26Figure 1 Total Alkalinity in Surface Watersof the Contiguous United States

### Page 22 of 26 

# Appendix B Ecotoxicology Profile Toxicity to Terrestrial Receptors

Birds

For indoor uses, an acute oral t oxicity study using the technical grade of the active ingredient (TGAI) is typically required for us e in establishing the toxicity of sodium carbonate to birds. A dietary study with a mallard duck using sodium carbonate was submitted to the Agency (MRID 00019437). Acceptability of the study has yet to be determined and the review is anticipated as being completed by the time of the Final Work Plan posting. However, based on the registered uses, environmental avian exposure to sodium car bonate is not expected, and additional studies are not expected to be required. 

# Toxicity to Aquatic Receptors

Freshwater Fish

For indoor uses, an acute study with a coldwater species using the T GAI is used to establish the toxicity of sodium carbonate to freshwater fish. No study with sodium carbonate has been submitted. Open literature values for carbonate toxi city from testing with sodium bicarbonate for seven fish species exist and are provided in Tabl e 7. This information is considered sufficient for hazard assessment purposes for effect of carbonate , and no additional information is expected to be needed at this time.

Table 7 – Aquatic Organism Sodium Ca rbonate and Bicarbonate Toxicology

Test Organisms Exposure Scenario and

Comments Test Substance (% Purity) Acute Toxicity Endpoints 1 Study Classification/ Toxicity Classification Reference NaHCO 3

(mg/L) Alkalinity as CaCO 3

(mg/L) HCO 3 - (mg/L)

Pallid sturgeon ( Scaphirhynchus albus ), 4 day post-hatch Freshwater 2,3 pH 8.16-8.95, 19

o C Control Alk/Carb/Bicarb 4 172/ 0 /210 NaHCO 3 96-h LC 50 = 1295 96-h LC 50 = 846 96-h LC 50 =

939 Acceptable Farag and Harper,

2012

Pallid sturgeon ( Scaphirhynchus albus ), 4 day post-hatch Freshwater 2,3 pH 8.06-8.76, 19

o C Control Alk/Carb/Bicarb 4 207/ 0 /252 NaHCO 3 96-h LC 50 = 1356 96-h LC 50 = 608 96-h LC 50 =

831 Acceptable Farag and Harper,

2012

Pallid sturgeon ( Scaphirhynchus albus ), 4 day post-hatch Freshwater 2,3 pH 8.06-8.76, 19

o C Control Alk/Carb/Bicarb 4 207/ 0 /252 NaHCO 3 96-h LC 50 = 1249 Acceptable Farag and Harper,

2012

### Page 23 of 26 Test Organisms Exposure Scenario and

Comments Test Substance (% Purity) Acute Toxicity Endpoints 1 Study Classification/ Toxicity Classification Reference NaHCO 3

(mg/L) Alkalinity as CaCO 3

(mg/L) HCO 3 - (mg/L)

Freshwater mussel ( Lampsilis siliquoidea ), newly transformed juveniles Freshwater 5 Static-renewal, pH 8.3-9.2, 19-22

o C Control Alk/Carb/Bicarb 4 182-204/ 10-13.1 /211-235 NaHCO 3 96-h LC 50 = 1120 (mean of 3

LC 50 s) 96-h LC 50 = 670 (mean of 3

LC 50 s) 96-h LC 50 =

844 (mean

of 3 LC 50 s) Acceptable Farag and Harper,

2012

White sucker ( Catostomus commersoni ), 2 days post-hatch Freshwater 2,5 Static-renewal pH 7.97-8.74, 16- 17 o C Control Alk/Carb/Bicarb 4 172/ 0 /210 NaHCO 3 96-h LC 50 = 4494 96-h LC 50 = 2668 96-h LC 50 = 3208 Supplemental Farag and Harper,

2012

White sucker ( Catostomus commersoni ), 2 days post-hatch Freshwater 2,5 Static-renewal pH 8.06-8.68, 16- 17 o C Control Alk/Carb/Bicarb 4 234/ 8 /274 NaHCO 3 96-h LC 50 = 5648 96-h LC 50 = 3852 96-h LC 50 = 4276 Supplemental Farag and Harper,

2012

White sucker (C. commersoni), 69 days post-hatch, 19.3 mm, 0.038
grams Freshwater Static-renewal Control Alk/Carb/Bicarb 4 177/ 0 /217 NaHCO 3 Supplemental Farag and Harper,

2012

Rainbow trout ( Oncorhynchus mykiss ), 2 days post-hatch sac fry Freshwater 3 pH 7.93-8.38, 10- 11 o C Control Alk/Carb/Bicarb 4 208/ 5.06 /248 NaHCO 3 96-h LC 50 = 8070 96-h LC 50 = 5134 96-h LC 50 =

5699 Acceptable Farag and Harper,

2012

Fathead minnow ( Pimphales promelas ), 4 days post-hatch Freshwater 2,3,7 pH 8.2-8.8, 23-26

o C Control Alk/Carb/Bicarb 4 172/ 0 /210 NaHCO 3 96-hr LC 50 >4000 mg/L (23% mortality) Supplemental Farag and Harper,

2012

Fathead minnow ( P

. promelas ), 2 days post-hatch Freshwater 2,3,7 pH 8.2-8.8, 23-26

o C Control Alk/Carb/Bicarb 4 210/ 11 /243 NaHCO 3 96-h LC 50 = 1749 96-h LC 50 = 1139 96-h LC 50 =

1254 Acceptable Farag and Harper,

2012

### Page 24 of 26 Test Organisms Exposure Scenario and

Comments Test Substance (% Purity) Acute Toxicity Endpoints 1 Study Classification/ Toxicity Classification Reference NaHCO 3

(mg/L) Alkalinity as CaCO 3

(mg/L) HCO 3 - (mg/L)

Fathead minnow ( P. promelas ), 4 days post-hatch Freshwater 2,3,7 pH 8.05-8.69, 24- 26 o C Control Alk/Carb/Bicarb 4 201/ 8 /193 NaHCO 3 96-h LC 50 = 2078 96-h LC 50 = 1089 96-h LC 50 =

1418 Acceptable Farag and Harper,

2012

Fathead minnow ( P. promelas ), fertilization to 60 days post-hatch Freshwater NaHCO 3 NOAEC

Walleye ( Sander vitreus ), 1 day post-hatch Freshwater 8 Static-renewal pH o C Control Alk/Carb/Bicarb 4 172/ 1 /209 NaHCO 3 96-h LC 50 = 3249 96-h LC 50 = 2022 96-h LC 50 = 2352 Acceptable Farag and Harper,

2012

Shovel nose sturgeon ( Scaphirhynchus platorynchus ), 1 day post-hatch Freshwater 8 pH o C Control Alk/Carb/Bicarb 4 94.5/ <1 / 115 NaHCO 3 96-h LC 50 = 1430 96-h LC 50 = 880 96-h LC 50 =

1038 Acceptable Farag and Harper,

2012

Northern pike ( Esox lucius ), 1 day post-hatch Freshwater 9 Control Alk/Carb/Bicarb 4 89.3/ 0 /108.9 NaHCO 3 96-h LC 50 = >8000 96-h LC 50 = >4181 96-h LC 50 = >8000 Supplemental Farag and Harper,

2012

African clawed frog ( Xenopus laevis ), <24 hr post-fertilization Freshwater 9 Static-renewal, pH 8.2-9.1, 22-24

o C Control Alk/Carb/Bicarb 192/ 12.3 /220 NaHCO 3 96-h LC 50 = 1940 (mean of 4 LC 50 s)

Non-lethal abnormalities: mild stunting and mild dorsal and lateral flexure of the tail 96-h EC 50 = 1108 (mean of 4 LC 50 s) 96-h LC 50 = 856 (mean of 4

LC 50 s) 96-h LC 50 =

914 (mean

of 4 LC 50 s) Acceptable Farag and Harper,

2012

Tubifex ( Tubifex tubifex ) Freshwater 9 Static-renewal, pH 7.3-9.2, 17-19

o C Control Alk/Carb/Bicarb 4 176/ 55.1 /207 NaHCO 3 96-h LC 50 = 3297 96-h LC 50 = 2119 96-h LC 50 = 2395 Acceptable Farag and Harper,

2012

### Page 25 of 26 Test Organisms Exposure Scenario and

Comments Test Substance (% Purity) Acute Toxicity Endpoints 1 Study Classification/ Toxicity Classification Reference NaHCO 3

(mg/L) Alkalinity as CaCO 3

(mg/L) HCO 3 - (mg/L)

Tubifex ( Tubifex tubifex ) Freshwater 9 Static-renewal, pH 8.2-9.3, 17-19

o C Control Alk/Carb/Bicarb 4 192/ 3.23 /229 NaHCO 3 96-h LC 50 = 3367 96-h LC 50 = 2427 96-h LC 50 = 2532 Acceptable Farag and Harper,

2012

Amphipod ( Hyalella azteca ), adults Freshwater 9 Static-renewal, pH 8.6-8.8, 23 o C Control Alk/Carb/Bicarb 4 156/ 8.98 /147 NaHCO 3 96-h LC 50 = 1419 96-h LC 50 = 966 96-h LC 50 =

1031 Acceptable Farag and Harper,

2012

Amphipod ( Hyalella azteca ), adults Freshwater 9 Static-renewal, pH 8.1-9.0, 23 o C Control Alk/Carb/Bicarb 4 199/ 6.15 /192 NaHCO 3 96-h LC 50 = 3851 96-h LC 50 = 966 96-h LC 50 =

1031 Acceptable Farag and Harper,

2012

Chironomid ( Chironomus dilutus ), 1-2 week old larvae Freshwater 9 Static-renewal, pH 8.1-9.5, 24-27

o C Control Alk/Carb/Bicarb 4 156/ <1.00 /190 NaHCO 3 48-h LC 50 = 4947 48-h LC 50 = 2903 48-h LC 50 = 3593 Supplemental Farag and Harper,

2012

Chironomid ( Chironomus dilutus ), 1-2 week old larvae Freshwater 9 Static-renewal, pH 8.1-9.3, 21-23

o C Control Alk/Carb/Bicarb 4 320/ 112 /254 NaHCO 3 48-h LC 50 = 8014 48-h LC 50 = 3874 48-h LC 50 =

5820 Supplemental Farag and Harper,

2012

Water flea, Ceriodaphnia dubia Freshwater Na 2 CO 3 48-h LC 50 = 220-227
ppm as Na 2 CO 3 Unacceptable 10 Warne et al. 1999 as

cited in OECD SIDS 2002

Water flea, Ceriodaphnia dubia , neonates Freshwater 11 Static-renewal, pH 8.4-9.2, 24-27

o C Control Alk/Carb/Bicarb 4 204/ 1 /249 NaHCO 3 48-h LC 50 = 989 48-h LC 50 = 734 48-h LC 50 =

699 Acceptable Farag and Harper,

2012

### Page 26 of 26 Test Organisms Exposure Scenario and

Comments Test Substance (% Purity) Acute Toxicity Endpoints 1 Study Classification/ Toxicity Classification Reference NaHCO 3

(mg/L) Alkalinity as CaCO 3

(mg/L) HCO 3 - (mg/L)

Water flea, C. daphnia dubia
, neonates Freshwater 11 Static-renewal, pH 8.1-9.3, 24-27

o C Control Alk/Carb/Bicarb 4 212/ 16 /239 NaHCO 3 48-h LC 50 = 1355 48-h LC 50 = 883 48-h LC 50 =

769 Acceptable Farag and Harper,

2012

Water flea, C. daphnia dubia
, neonates Freshwater 11 Static-renewal, pH 8.1-9.3, 24-27

o C Control Alk/Carb/Bicarb 4 212/ 16 /239 NaHCO 3 48-h LC 50 = 1288 48-h LC 50 = 8463 48-h LC 50 =

842 Acceptable Farag and Harper,

2012

1 Except as noted values based on measured concentrations.
2 Control water was reconstituted well water from Jackson Field Research Station. Control treatment for reconstituted water was 175 mg NaHCO 3 /L for Tongue River species except for with White sucker where control contained 267 mg NaHCO 3 /L and control was 194 mg NaHCO3/L for Powder River except with White sucker where 323 mg NaHCO3/L was used.
3 Unless specified otherwise, testing was conducted following USEPA 2002 protocols, used three replicates ten organisms each, 16 L:8 D
4 Conducted following protocol developed by Wang et al . (2007) and American Societ y for Testing and Materials International (2006); four replicates with five mussels per replicate.
5 Two replicates with eight fish per repli cate in the reconstituted Powder River water
6 Five fish per replicate in th e reconstituted Powder River water
7 Four replicates with five organisms per replicate
8 Four replicates with ten individuals per replicate
9 Conducted following standard guide for Conducting Frog Embryo Teratogenesis Assay-Xenopus (FETAX, American Society for Testing and Materi als International, 1998), two replicates per treatment with 25 embryos per replicate; test was repeated three times
10 SIDS document identified this study as invalid
11 Ten replicates with one individual per replicate