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:~"'" ~~. ~ u UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

S m WASHINGTON D.C., 20460 

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MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

February 15,2012 

Product Chemistry, Environmental Fate, and Ecological Effects Scoping 

Document in Support of Registration Review of Perboric acid, sodium 

salt, monohydrate (PBSM) 

PC Code: 011105 DP Barcode: 394845 

Decision No.: 455962 Registration Nos.: See Table 1 

Petition No(s).: NA Regulatory Action: Ecological 

Environmental Scoping Document 

for Registration Review 

Risk Assessment Type: Single Case No.: 5007 

chemical 

TXRNo.:NA CAS No.: 10332-33-9 

MRlD Nos.: See Page no. 4 40 CFR: None 

David 

Srinivas 

Bays, 

Gowda, 

PhD, 

Microbiologist/Science 

Microbiologist 

Coordinator Sroi ~ 

. 

V~ ~ 

Risk Assessment and Science Support Branch (RASSB) Ii J 1'1 ~ Antimicrobials Division (751OP) ~ /'-" /:?- --

Nader Elkassabany, PhD, Branch Chief / /' u' 

Donna 

Risk Assessment 

Randall, Ecological 

and Science 

Risk 

Support 

Assessment 

Branch 

Team 

(RASSB) 

Lea ~ 

Antimicrobials Division (751 OP) 

Mark Hartman, Branch Chief 

Lance Wormell, Team Leader 

Seiichi Murasaki, Chemical Review Manager 

Regulatory Management Branch II 

Antimicrobials Division (7510P) 

Page 1 of7 
Page 2 of 7

Executive Summary

Sodium perborate monohydrate (PBSM) is an inorganic, perboric acid salt, registered for 

use as a household laundry sanitizer. It was first registered in the United States on October 15, 

1998 as an active ingredient in Tide with Bleach, Tide with Bleach II, Gain with Bleach I, and 

Gain with Bleach II. A Reregistration Eligibility Decision (RED) has not been issued by the 

Agency for PBSM because the initial registration date was after the November 1984, federal

mandated cutoff for initiation of the RED process. Currently there is one company with two 

registered products, both are end-use products formulated as soluble concentrates, and the active 

ingredient declarations are 4.74 and 5.28 percent. All product chemistry data requirements have 

been satisfied for this active ingredient.

For these sanitizing laundry uses of PBSM the Agency will not require any additional 

environmental fate data or ecological effects data at this time. Due to its rapid reactivity and 

decomposition to oxygen, water, and boric acid—which are naturally occurring compounds 

widely found in soils, water, and food—these uses of PBSM are not expected to cause direct or 

indirect adverse effects to nontarget organisms. PBSM actually exists as a dimer anion in which 

two boron atoms are joined by two peroxo bridges, these peroxy functional groups make it very 

reactive, and it readily upon contact with aqueous medium hydrolyzes to hydrogen peroxide and 

borate. Hydrogen peroxide further rapidly breaks down into oxygen and water. The quantities of 

boric acid and sodium and ions introduced to the environment from the use of PBSM are 

considered modest compared to amounts used for other, non-pesticidal uses. Further, sodium, 

boric acid, and boron-containing salts are ubiquitous in the environment. Sodium and boron 

occur naturally in soils, water, fruits, vegetables, and forage crops. Boron is an essential nutrient 

for plants as well as an essential element for many organisms and sodium is an essential element 

for animals. Thus they are not considered as stressors in this assessment. At this time the agency 

does not feel that any environmental fate and transport data will be required to assess PBSM’s 

fate, effects or risk. Based on the rationale summarized above, the Agency expects that the 

registered uses of PBSM will have “no effect” 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 (NOAA).
Page 3 of 7

Introduction

Perboric acid, sodium salt, monohydrate (PBSM) was first registered as an active 

ingredient with EPA on October 15, 1998. It’s molecular formula NaBO3·H2O is a 

representation of the average chemical composition but it’s elementary structural unit is actually 

a dimer anion B2O4(OH)4

2-

, in which two boron atoms are joined by two peroxo bridges. 

Presently, two end-use products (EPs) are registered for use as a household laundry sanitizer and 

these are listed in Table 1. A Reregistration Eligibility Decision (RED) has not been issued by 

EPA for PBSM because the initial registration date was after November 1984, the federally 

mandated cutoff for initiation of the RED process.

Table 1. Registered Products of PBSM

Registration 

#

Registration

Name

Company

Name

Formulation 

Type

% of Active 

Ingredient

3573-56 Tide With Bleach II The Procter & Gamble 

Company

Soluble 

Concentrate

EP

5.28

3573-58 Gain With Bleach II The Procter & Gamble 

Company

Soluble 

Concentrate

EP

4.74

The Agency has conducted a review of the available product chemistry, environmental 

fate, and ecotoxicity data for PBSM. The findings are summarized below.

A. Product Chemistry Summary of the Perboric acid, sodium salt, monohydrate (95% 

TGAI Powder)

Common Name: Sodium Perborate Monohydrate

Chemical Name: Perboric acid, sodium salt, monohydrated (PBSM)

OPP Chemical Code: 011105

CAS Registry Number: 10332-33-9

Molecular Formula: NaBO3.H2O which exists as a dimer B2O4(OH)4

2-

Molecular weight: 99.81 g/mole

Molecular Structure:

Color: White.

Physical State: Solid Granules.

Odor: Odorless.

Stability: The product is stable under ambient conditions. 

pH: 10 (concentration 15.2 g/l)

UV/Visible absorption: Not applicable: ionic salt.

Melting point: Melting point is 63°C at which point it decomposes.
Page 4 of 7

Boiling Point: Not applicable, product is not a liquid.

Density: 0.4-0.65 g/ml

Dissociation Constant (pKa): Not applicable: ionic salt.

Log Ko/w: Not applicable because product is an inorganic compound 

that decomposes in water. 

Solubilities: Water: 15-16 g/l at 20 °C

Vapor Pressure: This is not applicable because of the ionic hydrated 

structure. It is considered to have negligible vapor pressure.

Enforcement Analytical

Method: Titration for available oxygen.

All product chemistry data requirements have been satisfied for the active ingredient

PBSM (Source: MRIDs 43603601, 44425602 and 45198501).

B. Environmental Fate Summary

For the laundry sanitizing use of PBSM the Agency will not require any environmental 

fate data at this time. PBSM has only two indoor use registrations. This chemical is an inorganic 

salt and environmental fate and transport test guidelines cannot be used to conduct the studies 

and obtain fate and transport parameters. In addition, it is a salt which contains a peroxy 

functional group which makes it very reactive, and it readily oxidizes/ breaks down in aqueous 

medium and is not likely to persist. Moreover, it will produce known ions which are already 

present in the environmental media like water and soils. At this time the agency does not feel that 

any environmental fate and transport data will be required to assess PBSM’s fate risk and 

characterization.

PBSM is considered to be a hydrogen peroxide releaser that also releases boric acid, a 

degradate that does not contribute to the pesticidal activity of PBSM. In both terrestrial and 

aquatic systems, PBSM rapidly degrades to form hydrogen peroxide, water, oxygen, and a minor 

(<10 % of applied) amount of borate by both abiotic and biotic means. There are no 

environmental concerns for any of the degradation products of PBSM based on their ubiquitous 

nature. In relation to boron, “Boric acid, borax, and boron-containing salts are ubiquitous in the 

natural environment. Boron occurs naturally in soil, water, fruits and vegetables and forage 

crops, and is an essential nutrient for plants as well as an essential element for many organisms. 

Humans ingest naturally occurring boron in the diet, and there is some data to suggest that trace 

levels are required in the human diet. Available boron occurs in nature in the form of a number 

of closely related compounds which differ chiefly in the water of hydration associated with the 

molecule and are not easily differentiated”.

1

 1 U.S. Environmental Protection Agency. 1993. Reregistration Eligibility Decision for Boric Acid And Its Sodium 

Salts. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs. September 1993.

EPA concluded that the relatively low levels of 

boron which would be added from pesticidal uses would not contribute to the already significant 

amounts of boron present in water and air. As a result, EPA waived the requirement for 

environmental fate data on boric acids and salts. Similarly, EPA waived the requirement for 

environmental fate data on hydrogen peroxide, based on the very rapid dissipation into water and 

oxygen. At this time there is no new information that changes this position for the PBSM 

registration review.
Page 5 of 7

Reaction of PBSM in Aqueous Solution

PBSM hydrolyzes in aqueous solution to release hydrogen peroxide and sodium metaborate. 

The following are the appropriate conversion factors for expressing concentrations of PBSM 

(CPBSM) as equivalent concentrations of:

• Boron: ; and

• Hydrogen peroxide: 

In aqueous solutions at room temperature equilibrium between PBSM and hydrogen peroxide

and sodium metaborate is instantly established (see reaction Equation I below).

Equation I

Further, the hydrogen peroxide is removed from the equilibrium—via degradation to active 

oxygen and water (reaction Equation II)—leading to an irreversible shift of the equilibrium given 

in Equation I to the degradation products sodium metaborate and water. The release of active 

oxygen also known as singlet oxygen (

1

O2) from hydrogen peroxide is the basis of the pesticidal 

activity of sodium perborate monohydrate.

–

Equation II

The degradation product, sodium metaborate, dissociates in water and is present primarily as 

dissociated boric acid or as boron (reaction Equation III and Equation IV). Boric acid and borates 

are naturally occurring compounds widely found in soils, water, and food. The bleaching activity 

of the perborates is associated with the hydrogen peroxide rather than the boric acid degradate.

Equation III

–

Equation IV

Reactions of PBSM and NOBS inside the Washing Machine 

PBSM and sodium nonanoyloxvbenzenesulfonate (NOBS; PC Code: 089053; 

CAS#91125-43-8) are active ingredients in the currently registered laundry detergent products 

Tide With Bleach II (EPA Reg. No. 3573-56) and Gain With Bleach II (EPA Reg. No. 3573-58)

by the Procter & Gamble Company. NOBS is a laundry bleach activator for hydrogen peroxide 

releasing chemicals such as PBSM. NOBS produces a highly active laundry bleach from the less 

reactive hydrogen peroxide.
Page 6 of 7

Detergent formulations containing NOBS are designed to help ensure rapid conversion of 

NOBS to the peroxy compound in the wash water. The peroxy compound itself is also shortlived due to rapid bleaching activity. To be effective in the wash cycle, the peracid precursor 

must be highly water-soluble, undergo rapid and total perhydrolysis, and produce a peracid 

bleach with surface activity. Bleach activators like NOBS essentially transfer active oxygen from 

the peroxide to the stain via the peracid. Reactions inside the washing machine are summarized 

below:

• PBSM supplies alkalinity (pH 10).

• PBSM hydrolyses, releasing hydrogen peroxide.

• Hydrogen peroxide perhydrolyzes NOBS, producing pernonanoic acid. NOBS is referred 

to as a “bleach activator” since it produces a highly active laundry bleach pernonanoic 

acid from the less reactive hydrogen peroxide. These reactions are largely complete 

within the first two minutes of the wash.

• Pernonanoic acid bleaches laundry soils by additions of oxygen and sanitizes laundry.

Most of the peracid bleach is consumed in the first eight minutes of the wash.

 

Sodium Nonanoyloxybenzensulfonate (NOBS) Hydrogen peroxide Pernonanoic acid laundry bleach

Water Quality

PBSM and boron (or borates) are not identified as a cause of impairment for any water 

bodies listed as impaired under section 303(d) of the Clean Water Act, based on information 

provided at the Agency’s National Pesticides Cause of Impairment of Waters website (searched 

April 7, 2011)2. In addition, no Total Maximum Daily Loads (TMDL) have been developed for

PBSM, based on information provided at the Agency’s National Pesticide TMDL web site 

(searched April 7, 2011)3

http://www.epa.gov/owow/tmdl/

. More information on impaired water bodies and TMDLs can be 

found at . 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 

Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf ), in 

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

 2 . http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 3

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

group_name=PESTICIDES
Page 7 of 7

C. Ecological Effects Summary

For the laundry sanitizing use of PBSM the Agency will not require any additional 

environmental effects toxicity data at this time, either for the parent or its major decomposition 

or degradate products. No exposure of nontarget organisms to PBSM is expected to occur in the 

environment because of its rapid reactivity and decomposition to oxygen, water, borates and 

boric acid. Water and oxygen are nontoxic degradates. As previously discussed in the 

Environmental Fate Summary section, sodium, boric acid, and boron-containing salts are 

ubiquitous in the environment. Sodium and boron occur naturally in soils, water, fruits, 

vegetables, and forage crops. Boron is an essential nutrient for plants as well as an essential 

element for many organisms and sodium is an essential element for animals. There is sufficient 

ecological effects data for boric acid and its sodium salts—discussed in the Boric Acid and Its 

Sodium Salt Reregistration Eligibility Decision4—documenting that boron is practically 

nontoxic to birds, fish and aquatic invertebrates.

Endangered Species Determination

Based on its rapid reactivity and decomposition to water, oxygen, and boric acid, the 

Agency expects that the registered indoor laundry sanitizing uses of PBSM will not lead to 

exposure and will have “no effect” on endangered or threatened terrestrial or aquatic species, or 

their designated critical habitats, as listed by the USFWS and the NOAA. However, the Agency

will review any comments made by the public on this document and will conduct an 

environmental risk assessment if new information warrants such action. An ecological risk 

assessment planned during registration review allows the Agency to determine whether an 

antimicrobial pesticide’s use has “no effect” or “may affect” federally listed threatened or 

endangered species (listed species) or their designated critical habitats. When an assessment 

concludes that a pesticide’s use “may affect” a listed species or its designated critical habitat, the 

Agency will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries 

Service (the Services), as appropriate.

Environmental Fate Data Gaps and Anticipated Work

For the laundry sanitizing use of PBSM the Agency will not require any additional 

environmental fate information. 

Ecotoxicity Data Gaps and Anticipated Work

Since no additional ecological effects studies are required, no ecotoxicity data gaps are 

present.

 4 U.S. Environmental Protection Agency. 1993. Reregistration Eligibility Decision for Boric Acid And Its Sodium 

Salts. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs. September 1993.