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 

Jepnifer McLain -

Acting Director 

Antimicrobials Division 

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Sodium Carbonate (formerly Weak Mineral 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 

 
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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 Registered 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 ............................................................................................................ 11

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 Model 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 Screening Program (EDSP) ................................................................. 14

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

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

6.1.1 Trade Irritants .......................................................................................................... 15
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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 Risk Assessments and Data Needs ......................................... 6

Table 2 - Anticipated Registration Review Schedule ..................................................................... 6

Table 3 - Chemical Identification of Sodium Carbonate ................................................................ 7

Table 4 - Physical-Chemical and Fate Properties for Sodium Carbonate ...................................... 7

Table 5 - Summary of Sodium Carbonate Registered Uses ........................................................... 8

Table 6 – Existing Effects Endpoints for Risk Assessment of Sodium Carbonate ...................... 13

Table 7 – Aquatic Organism Sodium Carbonate and Bicarbonate Toxicology............................ 22

List of Figures 

Figure 1 Total Alkalinity in Surface Waters of the Contiguous United States ............................. 21

 
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1 Introduction 

1.1 Statutory and Regulatory Authority 

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States generally must be registered by the U.S. 

Environmental Protection Agency (USEPA, EPA, or the Agency) based on scientific data 

showing that they will not cause unreasonable risks to human health or the environment when 

used as directed on product labeling. The registration review program is intended to make sure 

that, as the ability to assess risk evolves and as policies and practices change, all registered 

pesticides continue to meet the statutory standard of no unreasonable adverse effects to human 

health or the environment. Changes in science, public policy, and pesticide use practices will 

occur over time. Through the registration review program, the Agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used safely. 

Information on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/. 

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The Agency 

will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

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

comment period, the Agency will develop and commit to a Final Work Plan (FWP) and 

anticipated schedule for the Sodium Carbonate Case. 

Documents associated with this registration review can be viewed at http://www.regulations.gov 

in docket EPA-HQ-OPP-2012-0809. Below is a summary of the issues relevant to this 

registration review case. 

 
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Table 1 - Summary of Anticipated Risk Assessments and Data Needs 

Risk Assessment 

Assessment Necessary to 

Support Registration 

Review 

Date of Most 

Recent 

Assessment 

Type of Assessment 

Required 

(New/Updated) 

Data 

Anticipated as 

Needed 

Dietary (food) 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 Date1Completion Date

Phase 1: Opening 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 for 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 based, 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 Mineral Bases Case (or “Mineral Bases, Weak”) 

and included the chemically similar active ingredients sodium carbonate (PC Code 073506), 

potassium carbonate (PC Code 073504), sodium sesquicarbonate (PC Code 073507), and 

calcium hydroxide (PC Code 075601). Calcium hydroxide has since been moved to Case 51041

to be assessed with the active ingredient (a.i.) calcium oxide. Since 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 reflect that the only chemical 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 
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Carbonate Case (Case 4066) has been established at http://www.regulations.gov in docket 

number EPA-HQ-OPP-2012-0809. 

1.3 Chemical Identification and Properties 

Table 3 presents the active ingredient to be assessed in Case 4066: sodium carbonate (PC Code 

073506). Relevant sodium carbonate product chemistry information is summarized in Table 4. 

Table 3 - Chemical Identification of Sodium Carbonate 

Chemical Name Sodium Carbonate1

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 Na2CO3

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 Carbonate1

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/cm3 at 20 oC (anhydrous) 

830.7370 Dissociation Constant 

The pKa of CO3

2- is 10.33, (at a pH of 10.33, both carbonate and bicarbonate are 

present in equal amounts). The pKa of aqueous H2CO3 (combined aqueous CO2

and H2CO3) is 6.3 at 25 o

C and 0 ionic strength (at pH 6.3, about half the molar 

concentration exists as aqueous carbonic acid and half as bicarbonate (HCO3

-

)). 

830.7520 Particle size The average particle size diameter (d50) of light sodium carbonate is in the range 

of 90 to 150 μm and of dense sodium carbonate is in the range of 250 to 500 μm. 

830.7550 Partition coefficient 

(n-octanol/water) Kow is not determined for inorganic ionic substances 

830.7840 Solubility in water 71 g/L (0 oC), 215 g/L (20 oC), 455 g/L (100 oC) 

830.7950 Vapor pressure No measureable vapor pressure at room temperature 

1

 Source: OECD SIDS, 2002 
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1.4 Use/Usage Description 

Products containing sodium carbonate 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 carbonate as an active ingredient 

(a.i.). The percent a.i. ranges from 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 uses of sodium carbonate. Sodium carbonate can be 

applied by the following application methods: mop, wipe, spray, cold fogger, brush, roller, and 

immersion. 

Table 5 - Summary of Sodium Carbonate Registered Uses 

Use Application Method Application Rate

Commercial, Industrial, Institutional, Residentiala Premisesb 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/ft2 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/ft2 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 Institutions – 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%
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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-food 

contact), home furnishings, house wares (nonfood contact only), floor coverings, sporting 

goods, apparel, filmsc, 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 Remediation 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/ft2 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 Seven Tracking System (SSTS) for the years 2004 

through 2009 indicate that no more than 150,000 kilograms of pesticidal sodium carbonate are 

sold per year in the United States2. 

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 Sodium Carbonate; Weak 

Mineral Acids in 20064

. 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 expanded in 2005 to include mold, mildew, and fungi 

remediation on hard surfaces of commercial, industrial, institutional, and residential building and 

construction materials, building premises, contents and furnishings, 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_actions/reregistration/red_PC-073506_26-Jan-06.pdf 
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1.5.1 Recent/Pending Regulatory Actions 

There are no recent regulatory actions for sodium 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 tolerance 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 substance (21 CFR §184.1742); no limit is placed on the amount of sodium 

carbonate added to food except current 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 resulting from its use as a registered antimicrobial 

have been reported in the Agency’s Ecological Incident Information System (EISS, v2.10) 

through 2012. 

2 Anticipated Data Needs 

The Agency does not anticipate the need to require additional data to support this registration 

review. 

3 Human Health Risk Assessment 

The Agency does not anticipate the need to conduct a human health risk assessment for sodium 

carbonate nor does the Agency expect to require additional data for use in conducting the 

registration review. Comprehensive reviews of the toxicology of sodium carbonate have been 

conducted by regulatory organizations 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 included unpublished studies submitted to the Agency 

and published literature, and concluded that the toxicological database for sodium carbonate was 

sufficient for reregistration. Based on previous reviews and the currently registered uses, the 

Agency believes that the toxicological information of sodium carbonate is adequate for the 

purposes of registration review. There 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. 
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3.1 Existing Toxicological Endpoints 

There are no toxicological endpoints of concern for oral, dermal, or inhalation exposure to 

sodium carbonate and there is no evidence of increased susceptibility in a developmental toxicity 

study. 

3.2 Dietary Exposure 

There are no toxicological endpoints of concern for oral exposure to sodium carbonate; therefore, 

dietary and drinking water exposures are not expected to be assessed. 

3.3 Occupational and Residential Exposures 

There are no toxicological endpoints of concern for dermal, inhalation, and incidental oral 

exposures to sodium carbonate; therefore, occupational and residential exposures are not 

expected to be assessed. 

3.4 Aggregate and Cumulative Exposure 

3.4.1 Aggregate Exposures 

There are no toxicological endpoints of concern for oral, dermal, inhalation, and incidental oral 

exposures to sodium carbonate; therefore, aggregate exposures are not expected 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 mechanism of toxicity, EPA has not made a 

common mechanism of toxicity finding as to sodium 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 have a common mechanism of toxicity and to 

evaluate the cumulative effects of such chemicals, see 

http://www.epa.gov/pesticides/cumulative/. 

4 Environmental Risk Assessment 

The Agency does not anticipate the need to conduct a quantitative ecological risk assessment for 

sodium carbonate. The hard surface and fabric sanitizer, disinfectant, and fungicide use patterns 

of sodium carbonate are expected to result in minor or insignificant 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 material preservative uses are also not expected to result in any 

significant amounts of sodium carbonate reaching surface waters; additionally, the use of treated 

agricultural and mulch films are not expected to significantly change the soil pH and alkalinity at 

use sites. 
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Based on the low hazard and exposure, the Agency intends to conclude that the registered uses of 

sodium carbonate will have 'no effect' (NE) on endangered 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 Atmospheric Administration's (NOAA) National 

Marine Fisheries Service (NMFS). EPA anticipates conducting no further analysis of potential 

risks to endangered or threatened 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 fungicide 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). Compared to volumes of soda ash (sodium carbonate) 

consumed annually in the United States for pH and alkalinity adjustment in water treatment and 

buffering and pH balance in soaps and detergents5, input into the wastewater treatment stream 

from hard surface use is not expected to have a significant impact. 

Treated porous and semi-porous materials will 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 essentially remain with treated materials in situ. Except 

for material preservative uses in agricultural and 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. While agricultural and mulch films 

and silage wraps will be used outdoors where non-target organisms 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 pH6 or alkalinity7, 

significant quantities of carbonate would need to be discharged, and such quantities are not 

expected for the registered uses. 

4.2 Ecological Effects Assessment 

Ecological effects data are used as measures to evaluate 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 support of registration and the ecotoxicological 

endpoints summarized in Table 6 are based on the peer-reviewed literature. A more detailed 

description of the ecotoxicity studies is provided 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://minerals.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/waterscience/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 maintenance of acid-base balance in the blood and 

hemolymph, and increase of the pH (OECD SIDS 2002; Fagar and Harper, 2012). 

4.2.2 Measures of Effect (Ecotoxicology Endpoints) 

Available ecotoxicological endpoints are summarized in Table 6. A more detailed description of 

the ecotoxicity studies are provided in Appendix B . 

Table 6 – Existing Effects Endpoints for Risk Assessment of Sodium Carbonate 

Receptor Group Surrogate Species Risk 

Scenario 

Toxicity Endpoint 

Comment Reference HCO3

- Alkalinity as 

CaCO3

Freshwater fish 

Rainbow trout 

(Oncorhyncus mykiss) Acute 96-hr LC50 = 5699 

ppm 

96-hr LC50 = 

5699 ppm 

Farag and 

Harper, 2012 

Pallid sturgeon 

(Scaphirhynchus albus) Acute 96-hr LC50 = 831 ppm 

96-hr LC50 = 

608 ppm Acceptable Farag and Harper, 2012 

 Chronic Data not required for Na2CO3 for these uses 

Freshwater 

invertebrates 

Freshwater mussel 

(Lampsilis siliquoidea) Acute 96-hr LC50 = 844 

ppm 

96-hr LC50 = 

670 ppm Acceptable Farag and 

Harper, 2012 

 Chronic Data not required for registered Na2CO3 uses 

Estuarine/ Marine 

fish 

 Acute Data not required for registered Na2CO3 uses 

 Chronic Data not required for registered Na2CO3 uses 

Estuarine/ Marine 

invertebrates 

Shrimp Acute Data not required for registered Na2CO3 uses 

Chronic Data not required for registered Na2CO3 uses 

Mollusk Acute Data not required for registered Na2CO3 uses 

Algae Green algae 

Chronic 

(EC50) Data not required for registered Na2CO3 uses 

Chronic 

(NOAEC) Data not required for registered Na2CO3 uses 

Aquatic Vascular 

plants Lemna sp. Chronic Data not required for registered Na2CO3 uses 

Birds Acute Data not required for registered Na2CO3 uses 

Mammals Rat Acute LD50 = 2800 mg 

Na2CO3/kg-bw 

OECD SIDS 

2002 

Chronic Data not required for registered Na2CO3 uses 

4.3 Exposure Analysis Plan 

The Agency does not anticipate the need to further refine exposure from sodium carbonate uses 

for the registration review. 

4.4 Effects Analysis Plan 

As part of the the data required 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 algal study is not required since 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 after down-the-drain disposal of compounds containing sodium 

carbonate. Because waste water is treated by water treatment plants before effluents are released 

into the environment to adjust to appropriate pH limits and dilutions in relation to the natural pH 

and buffering capacity of the receiving water, adverse effects to the aquatic environment, 

including algae, are not expected to result from the use and disposal of sodium carbonate 

containing pesticidal products (OECD SIDS, 2002). 

5 Endocrine Disruptor Screening Program (EDSP) 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. 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 endocrine screening part of the Endocrine Disruptor Screening 

Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and nine inert ingredients. Sodium carbonate is 

not among the group of 58 pesticide active ingredients on the initial list to be screened under the 

EDSP. Accordingly, as part of registration review, EPA will issue future EDSP orders/data callins, requiring the submission of EDSP screening assays for sodium carbonate. 
Page 15 of 26

For further information on the status of the EDSP, the policies and procedures, the list of 67 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/. 

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 Agency intends to solicit information on trade 

irritants and, to the extent feasible, 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 from lack of MRLs or disparities between U.S. tolerances and 

MRLs in key export markets, providing as much specificity as possible regarding the nature of 

the concern. 

6.1.2 Water Quality 

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 Act8

. However, carbonate alkalinity, which 

increases when sodium carbonate is dissolved in an aqueous medium, is identified as a cause of 

impairment, as defined under section 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 website9. 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 Nebraska9,10; pH—unidentified as 

high or low, is identified as the cause of impairment in 4,050 waterbodies. Sodium is identified 

as a cause of impairment, as defined under section 303(d) of the Clean Water Act, in seven 

waterbodies: four in California, one in Connecticut, and two in Montana9. 

Of the sodium listings according to California Regional Board 6 – Lahontan Region, the two 

listings for the West Fork Carson River were placed on the 303(d) list for Percent Sodium11

rather than sodium but were listed as “sodium” because it was the only choice available in the 

database in use at that time. Percent Sodium is the ratio of sodium ion concentration to the sum 

of the concentrations of calcium, magnesium and 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_impaired_waters.control?p_cause_name=PH,%20HIGH (accessed 

October 4, 2012) 

11 http://www.waterboards.ca.gov/lahontan/water_issues/programs/tmdl/303d_305b/factsheets/01425.shtml 

(accessed October 4, 2012) 
Page 16 of 26

irrigation water criterion and has being replaced with a new objective “Sodium Adsorption 

Ratio” or SAR12. 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 has been obtained in 19 out of 19 years. Sodium in one of the 

Montana sites is attributed to flow and agricultural sources13. 

In Montana, high levels of sodium bicarbonate (>1,000 mg/L) occur in areas resulting from 

wastewater disposal from coal-bed natural gas drilling. There is neither an EPA nor State of 

Montana water quality criterion for 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 developed 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 states14 and the District of Columbia based on information provided at 

the website15,16. More information on impaired water bodies and TMDLs can be found at EPA’s 

website17. The Agency invites submission of water quality data for this pesticide. To the 

extent possible, data should conform to the quality standards in Appendix A of the OPP 

Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water Quality 

Data in OPP’s Registration Review Risk Assessment and Management Process18 in order to 

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

6.1.3 Environmental Justice 

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

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

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

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

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

atypical, unusually high exposure to 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/FINAL_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#tmdl_by_pollutant (accessed 

October 4, 2012) 

16http://ofmpub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_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 quality and reliability for each decision made by 

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

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

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

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

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

adverse effect can occur in various animal species. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

appropriate because the risk assessment for lower toxicity chemicals can be stream-lined, i.e., a 

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

more data requirements. 

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

Sodium Carbonate Case, then the Agency invites submission of this information. The submitter 

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

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

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

consultation with the Agency is encouraged. 
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, application intervals and maximum number of 

applications 

F. Geographic limitations on use 

2. Use or potential use distribution 

3. Use history 

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

5. Typical application interval 

6. State or local use restrictions 

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

mammalian mortalities) not already reported to the Agency 

8. Monitoring data 

7 Next Steps 

After the 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 Carbonate, CAS No: 497-19-8. 

http://www.inchem.org/documents/sids/sids/Naco.pdf 

Farag, A. M. and Harper, D.D. eds. 2012 The potential effects of sodium bicarbonate, a major 

constituent of produced waters from coalbed natural gas production, on aquatic life. U.S. 

Geological Survey, Scientific Investigations 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 (Na2CO3), which means it 

contains no water of hydration. Anhydrous sodium carbonate (Na2CO3) is an inorganic ionic 

substance; it is highly water soluble and dissociates in water completely to form sodium ions 

(Na+

) and carbonate ions (CO3

-2). Sodium carbonate’s high water solubility and negligible vapor 

pressure means that it will be associated primarily with the aquatic environment. From 

environmental fate perspective, photodegradation 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 formation of bicarbonate, carbonic acid and carbon 

dioxide. The chemistry of carbonate in solution is that of carbonic acid (H2CO3) equilibrium 

chemistry and is based on the following three universal reactions: 

COଶ

஼௔௥௕௢௡ ௗ௜௢௫௜ௗ௘ ሺ௔௤௨௘௢௨௦ሻ

൅ HଶO

ௐ௔௧௘௥

 

՞ H2COଷ

஼௔௥௕௢௡௜௖ ௔௖௜ௗ

 Equation 1 

H2COଷ

஼௔௥௕௢௡௜௖ ௔௖௜ௗ

 

՞ HCOଷ

ି

஻௜௖௔௥௕௢௡௔௧௘ ௜௢௡

൅ Hା

ு௬ௗ௥௢௡௜௨௠ ௜௢௡

 Equation 2 

HCO3

ି

஻௜௖௔௥௕௢௡௔௧௘ ௜௢௡

 

՞ COଷ

ଶି

஼௔௥௕௢௡௔௧௘ ௜௢௡

൅ Hା

ு௬ௗ௥௢௡௜௨௠ ௜௢௡

 Equation 3 

The form of carbonate in solution depends on the pH of the aqueous 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 (H2CO3). Between the pH range of 4.3 to 12.3, the bicarbonate ion (HCO3

-

) is 

the predominate moiety form of carbonate. Around pH 8.3, some carbonate also exists as the 

carbonate ion (CO3

2

), but it is the predominant form in the most basic range (pH 12 to 14). 

Carbonic acid in solution is in equilibrium with dissolved carbon dioxide (CO2). The amount of 

dissolved CO2 is controlled by the partial pressure of CO2 in the atmosphere. These equilibria are 

the major buffer of pH for freshwater and saltwater systems. 

In natural waters, alkalinity19 of the medium is attributable primarily to the presence of HCO3

-

/CO3

2- species due to the common occurrence and dissolution of carbonate rocks and CO2 in the 

atmosphere. Other common natural components can contribute to alkalinity including borate 

(B(OH)4

-

), hydroxide (OH-), phosphate (PO4

3-, HPO42-), silicate (SiO(OH)3-

), nitrate (NO3

-

), and 

conjugate bases of some organic bases of some organic acids and sulfide. 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: 

AlkalinityTotal= ቂHCO3

-

ቃ

T

+2 ቂCO3

2-ቃ

T

+ ቂBሺOHሻ4

-

ቃ

T

+ ቂOHቃ

T

+2 ቂPO4

3-ቃ

T

+ ቂHPO4

2-ቃ

T

+ሾSiOሺOHሻଷ

ିሿT-ൣH+൧

SWS-ቂHSO4

-

ቃ

T

 

Brackets indicate concentration and the T subscript means the total concentration of the species in solution. 

Common natural constituents contributing to alkalinity include carbonate (HCO3-, CO3

2-), borate (B(OH)4-

), 

hydroxide (OH-

), phosphate (PO4

3-, HPO42-), silicate (SiO(OH)3-

), nitrate (NO3

-

), and conjugate bases of some 

organic bases of some organic acids and sulfide, While a number of constituents can contribute to alkalinity, HCO3-

and CO3

2- predominate in most natural systems. 
Page 20 of 26

capacity to resist the change in pH. This characteristic drives the aquatic and terrestrial ecotoxic 

effects of sodium carbonate/sodium bicarbonate. 

Bicarbonate and Alkalinity in surface waters 

Bicarbonate is present universally in global rivers from 20 mg/L (low level)) to 190 mg/L (high 

level). Based on 77 rivers in North-America, South-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 States is provided in 

Figure 1. 

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

The sodium ion is ubiquitously present in the environment and it has been measured extensively 

in aquatic ecosystems. Sodium and chloride concentrations in water are tightly linked. They both 

originate from natural weathering of rock, from atmospheric transport of oceanic inputs and from 

a wide variety of anthropogenic sources. The natural 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, Europe 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. 
Page 21 of 26

Figure 1 Total Alkalinity in Surface Waters of the Contiguous United States 
Page 22 of 26

Appendix B Ecotoxicology Profile 

Toxicity to Terrestrial Receptors 

Birds

For indoor uses, an acute oral toxicity study using the technical grade of the active ingredient 

(TGAI) is typically required for use 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 carbonate 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 TGAI 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 toxicity from testing with sodium bicarbonate for 

seven fish species exist and are provided in Table 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 Carbonate and Bicarbonate Toxicology 

Test Organisms 

Exposure 

Scenario and 

Comments 

Test 

Substance

(% 

Purity) 

Acute Toxicity Endpoints1 Study 

Classification/ 

Toxicity 

Classification 

Reference

NaHCO3

(mg/L) 

Alkalinity 

as CaCO3

(mg/L) 

HCO3

-

(mg/L)

Pallid sturgeon 

(Scaphirhynchus 

albus), 4 day 

post-hatch 

Freshwater2,3

pH 8.16-8.95, 19 

o

C 

Control 

Alk/Carb/Bicarb4

172/ 0 /210 

NaHCO3

96-h LC50 = 

1295 

96-h LC50

= 846 

96-h 

LC50 = 

939 

Acceptable 

Farag and 

Harper, 

2012 

Pallid sturgeon 

(Scaphirhynchus 

albus), 4 day 

post-hatch 

Freshwater2,3

pH 8.06-8.76, 19 

o

C 

Control 

Alk/Carb/Bicarb4

207/ 0 /252 

NaHCO3

96-h LC50 = 

1356 

96-h LC50

= 608 

96-h 

LC50 = 

831 

Acceptable 

Farag and 

Harper, 

2012 

Pallid sturgeon 

(Scaphirhynchus 

albus), 4 day 

post-hatch 

Freshwater2,3

pH 8.06-8.76, 19 

o

C 

Control 

Alk/Carb/Bicarb4

207/ 0 /252 

NaHCO3

96-h LC50 = 

1249 Acceptable 

Farag and 

Harper, 

2012 
Page 23 of 26

Test Organisms 

Exposure 

Scenario and 

Comments 

Test 

Substance

(% 

Purity) 

Acute Toxicity Endpoints1 Study 

Classification/ 

Toxicity 

Classification 

Reference

NaHCO3

(mg/L) 

Alkalinity 

as CaCO3

(mg/L) 

HCO3

-

(mg/L)

Freshwater 

mussel 

(Lampsilis 

siliquoidea), 

newly 

transformed 

juveniles 

Freshwater5

Static-renewal, 

pH 8.3-9.2, 19-22 

o

C 

Control 

Alk/Carb/Bicarb4

182-204/ 10-13.1 

/211-235 

NaHCO3

96-h LC50 = 

1120 

(mean of 3 

LC50s) 

96-h LC50

= 670 

(mean of 3 

LC50s) 

96-h 

LC50 = 

844 

(mean 

of 3 

LC50s) 

Acceptable 

Farag and 

Harper, 

2012 

White sucker 

(Catostomus 

commersoni), 2 

days post-hatch 

Freshwater2,5 

Static-renewal 

pH 7.97-8.74, 16-

17 o

C 

Control 

Alk/Carb/Bicarb4

172/ 0 /210 

NaHCO3

96-h LC50 = 

4494 

96-h LC50

= 2668 

96-h 

LC50 = 

3208 

Supplemental 

Farag and 

Harper, 

2012 

White sucker 

(Catostomus 

commersoni), 2 

days post-hatch 

Freshwater2,5 

Static-renewal 

pH 8.06-8.68, 16-

17 o

C 

Control 

Alk/Carb/Bicarb4

234/ 8 /274 

NaHCO3

96-h LC50 = 

5648 

96-h LC50

= 3852 

96-h 

LC50 = 

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/Bicarb4

177/ 0 /217 

NaHCO3 Supplemental 

Farag and 

Harper, 

2012 

Rainbow trout 

(Oncorhynchus 

mykiss), 2 days 

post-hatch sac fry 

Freshwater3

pH 7.93-8.38, 10-

11 o

C 

Control 

Alk/Carb/Bicarb4

208/ 5.06 /248 

NaHCO3

96-h LC50 = 

8070 

96-h LC50

= 5134 

96-h 

LC50 = 

5699 

Acceptable 

Farag and 

Harper, 

2012 

Fathead minnow 

(Pimphales 

promelas), 4 days 

post-hatch 

Freshwater2,3,7

pH 8.2-8.8, 23-26 

o

C 

Control 

Alk/Carb/Bicarb4

172/ 0 /210 

NaHCO3

96-hr LC50

>4000 mg/L 

(23% 

mortality) 

 Supplemental 

Farag and 

Harper, 

2012 

Fathead minnow 

(P. promelas), 2 

days post-hatch 

Freshwater2,3,7

pH 8.2-8.8, 23-26 

o

C 

Control 

Alk/Carb/Bicarb4

210/ 11 /243 

NaHCO3

96-h LC50 = 

1749 

96-h LC50

= 1139 

96-h 

LC50 = 

1254 

Acceptable 

Farag and 

Harper, 

2012 
Page 24 of 26

Test Organisms 

Exposure 

Scenario and 

Comments 

Test 

Substance

(% 

Purity) 

Acute Toxicity Endpoints1 Study 

Classification/ 

Toxicity 

Classification 

Reference

NaHCO3

(mg/L) 

Alkalinity 

as CaCO3

(mg/L) 

HCO3

-

(mg/L)

Fathead minnow 

(P. promelas), 4 

days post-hatch 

Freshwater2,3,7

pH 8.05-8.69, 24-

26 o

C 

Control 

Alk/Carb/Bicarb4

201/ 8 /193 

NaHCO3

96-h LC50 = 

2078 

96-h LC50

= 1089 

96-h 

LC50 = 

1418 

Acceptable 

Farag and 

Harper, 

2012 

Fathead minnow 

(P. promelas), 

fertilization to 60 

days post-hatch 

Freshwater NaHCO3 NOAEC 

Walleye (Sander 

vitreus), 1 day 

post-hatch 

Freshwater8

Static-renewal 

pH o

C 

Control 

Alk/Carb/Bicarb4

172/ 1 /209 

NaHCO3

96-h LC50 = 

3249 

96-h LC50

= 2022 

96-h 

LC50 = 

2352 

Acceptable 

Farag and 

Harper, 

2012 

Shovel nose 

sturgeon 

(Scaphirhynchus 

platorynchus), 1 

day post-hatch 

Freshwater8

pH oC 

Control 

Alk/Carb/Bicarb4

94.5/ <1 / 115 

NaHCO3

96-h LC50 = 

1430 

96-h LC50

= 880 

96-h 

LC50 = 

1038 

Acceptable 

Farag and 

Harper, 

2012 

Northern pike 

(Esox lucius), 1 

day post-hatch 

Freshwater9

Control 

Alk/Carb/Bicarb4

89.3/ 0 /108.9 

NaHCO3

96-h LC50 = 

>8000 

96-h LC50

= >4181 

96-h 

LC50 = 

>8000 

Supplemental 

Farag and 

Harper, 

2012 

African clawed 

frog (Xenopus 

laevis), <24 hr 

post-fertilization 

Freshwater9

Static-renewal, 

pH 8.2-9.1, 22-24 

o

C 

Control 

Alk/Carb/Bicarb 

192/ 12.3 /220 

NaHCO3

96-h LC50 = 

1940 (mean of 

4 LC50s) 

Non-lethal 

abnormalities: 

mild stunting 

and mild dorsal 

and lateral 

flexure of the 

tail 

96-h EC50 = 

1108 (mean of 

4 LC50s) 

96-h LC50

= 856 

(mean of 4 

LC50s) 

96-h 

LC50 = 

914 

(mean 

of 4 

LC50s) 

Acceptable 

Farag and 

Harper, 

2012 

Tubifex (Tubifex 

tubifex) 

Freshwater9

Static-renewal, 

pH 7.3-9.2, 17-19 

o

C 

Control 

Alk/Carb/Bicarb4

176/ 55.1 /207 

NaHCO3

96-h LC50 = 

3297 

96-h LC50

= 2119 

96-h 

LC50 = 

2395 

Acceptable 

Farag and 

Harper, 

2012 
Page 25 of 26

Test Organisms 

Exposure 

Scenario and 

Comments 

Test 

Substance

(% 

Purity) 

Acute Toxicity Endpoints1 Study 

Classification/ 

Toxicity 

Classification 

Reference

NaHCO3

(mg/L) 

Alkalinity 

as CaCO3

(mg/L) 

HCO3

-

(mg/L)

Tubifex (Tubifex 

tubifex) 

Freshwater9

Static-renewal, 

pH 8.2-9.3, 17-19 

o

C 

Control 

Alk/Carb/Bicarb4

192/ 3.23 /229 

NaHCO3

96-h LC50 = 

3367 

96-h LC50

= 2427 

96-h 

LC50 = 

2532 

Acceptable 

Farag and 

Harper, 

2012 

Amphipod 

(Hyalella azteca), 

adults 

Freshwater9

Static-renewal, 

pH 8.6-8.8, 23 o

C 

Control 

Alk/Carb/Bicarb4

156/ 8.98 /147 

NaHCO3

96-h LC50 = 

1419 

96-h LC50

= 966 

96-h 

LC50 = 

1031 

Acceptable 

Farag and 

Harper, 

2012 

Amphipod 

(Hyalella azteca), 

adults 

Freshwater9

Static-renewal, 

pH 8.1-9.0, 23 o

C 

Control 

Alk/Carb/Bicarb4

199/ 6.15 /192 

NaHCO3

96-h LC50 = 

3851 

96-h LC50

= 966 

96-h 

LC50 = 

1031 

Acceptable 

Farag and 

Harper, 

2012 

Chironomid 

(Chironomus 

dilutus), 1-2 

week old larvae 

Freshwater9

Static-renewal, 

pH 8.1-9.5, 24-27 

o

C 

Control 

Alk/Carb/Bicarb4

156/ <1.00 /190 

NaHCO3

48-h LC50 = 

4947 

48-h LC50

= 2903 

48-h 

LC50 = 

3593 

Supplemental 

Farag and 

Harper, 

2012 

Chironomid 

(Chironomus 

dilutus), 1-2 

week old larvae 

Freshwater9

Static-renewal, 

pH 8.1-9.3, 21-23 

o

C 

Control 

Alk/Carb/Bicarb4

320/ 112 /254 

NaHCO3

48-h LC50 = 

8014 

48-h LC50

= 3874 

48-h 

LC50 = 

5820 

Supplemental 

Farag and 

Harper, 

2012 

Water flea, 

Ceriodaphnia 

dubia

Freshwater Na2CO3 

48-h 

LC50 = 

220-227 

ppm as 

Na2CO3

Unacceptable10

Warne et 

al. 1999 as 

cited in 

OECD 

SIDS 2002

Water flea, 

Ceriodaphnia 

dubia, neonates 

Freshwater11

Static-renewal, 

pH 8.4-9.2, 24-27 

o

C 

Control 

Alk/Carb/Bicarb4

204/ 1 /249 

NaHCO3

48-h LC50 = 

989 

48-h LC50

= 734 

48-h 

LC50 = 

699 

Acceptable 

Farag and 

Harper, 

2012 
Page 26 of 26

Test Organisms 

Exposure 

Scenario and 

Comments 

Test 

Substance

(% 

Purity) 

Acute Toxicity Endpoints1 Study 

Classification/ 

Toxicity 

Classification 

Reference

NaHCO3

(mg/L) 

Alkalinity 

as CaCO3

(mg/L) 

HCO3

-

(mg/L)

Water flea, C. 

daphnia dubia, 

neonates 

Freshwater11

Static-renewal, 

pH 8.1-9.3, 24-27 

o

C 

Control 

Alk/Carb/Bicarb4

212/ 16 /239 

NaHCO3

48-h LC50 = 

1355 

48-h LC50

= 883 

48-h 

LC50 = 

769 

Acceptable 

Farag and 

Harper, 

2012 

Water flea, C. 

daphnia dubia, 

neonates 

Freshwater11

Static-renewal, 

pH 8.1-9.3, 24-27 

o

C 

Control 

Alk/Carb/Bicarb4

212/ 16 /239 

NaHCO3

48-h LC50 = 

1288 

48-h LC50

= 8463 

48-h 

LC50 = 

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 NaHCO3/L for Tongue River species except for with White sucker where control 

contained 267 mg NaHCO3/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 Society for Testing and Materials 

International (2006); four replicates with five mussels per replicate. 

5

 Two replicates with eight fish per replicate in the reconstituted Powder River water 6

 Five fish per replicate in the 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 Materials 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