Potassium metaborate

Toxicity to reproduction

Administrative data

Endpoint:

reproductive toxicity, other

Remarks:

various methods are presented in this report

Type of information:

experimental study

Remarks:

publication / peer-reviewed report

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

peer-reviewed

Data source

Reference

Reference Type:

review article or handbook

Title:

Final Report on the Safety Assessment of Sodium Borate and Boric Acid

Author:

CIR

Year:

1983

Bibliographic source:

JOURNAL OF THE AMERICAN COLLEGE OF TOXICOLOGY, Volume 2, Number 7, 1983 Mary Ann Liebert, Inc., Publishers

Materials and methods

Test guideline

Qualifier:

no guideline required

Principles of method if other than guideline:

Review of literature data

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Boric acid

EC Number:

233-139-2

EC Name:

Boric acid

Cas Number:

10043-35-3

Molecular formula:

H3BO3

IUPAC Name:

Boric acid

Constituent 2

Reference substance name:

1303-96-4

EC Number:

603-411-9

Cas Number:

1303-96-4

IUPAC Name:

1303-96-4

Details on test material:

Boric Acid (CAS No. 10043-35-3) is an inorganic acid that conforms to the formula, H3B03. It is also called boracic acid and orthoboric acid. Sodium Borate (CAS No. 1303-96-4) is an inorganic salt that conforms to the formula, Na2B4O7*10H2O. It is also called borax and sodium tetraborate. Sodium Borate occurs in pentahydrate and anhydrous forms as well as the decahydrate form. The decahydrate is the Sodium Borate that appears in the FDA product formulation computer printout and the use of the name, Sodium Borate, in the chemistry section of this report refers to the decahydrate. In references appearing in other sections of this report the specific Sodium Borate has not usually been identified.
Boric Acid occurs as colorless, odorless, transparent, triclinic crystals or white granules or powder that is slightly oily to the touch. It has a molecular weight of 61.84 and a specific gravity of 1.435. A 0.1 M solution of Boric Acid has a pH of 5.1. Boric Acid is stable in air but volatile in steam without decomposition. Its melting point is approximately 171°C when heated in a closed space. With continued heating and higher temperatures, Boric Acid loses water in stages. It becomes metaboric acid, HBO2, and then pyroboric acid, H2B4O7, followed by the oxide, B2O3. Boric Acid is soluble in hot and cold water, alcohol, and glycerin. Its solubility in water is increased by citric, hydrochloric, and tartaric acids. It is slightly soluble in acetone and not very soluble in ether.
Sodium Borate occurs colorless to white, hard, odorless, monoclinic crystals or powder. It is efflorescent in dry air and crystals are often coated with white powder. It has a molecular weight of 381.37 and a specific gravity of 1.73. An aqueous solution of Sodium Borate has a pH of approximately 9.5. When heated rapidly, Sodium Borate has a melting point of 75°C. It becomes anhydrous at 320°C. Sodium Borate is soluble in hot and cold water, and glycerin. It is very slightly soluble in alcohol and is insoluble in acid.

Test animals

Species:

rat

Strain:

other: various

Sex:

male/female

Details on test animals or test system and environmental conditions:

no data

Administration / exposure

Route of administration:

oral: unspecified

Applicant's summary and conclusion

Conclusions:

The present information was based on a literature review (peer-reviewed) of sodium borate and boric acid studies. Most, but not all reviewed studies indicated that boron had adverse effects on reproduction, more specific on the gonads of the males. Nevertheless, due to the limited information, obvious threshold and some deviating results, data does not suffice for classification as Repr. 1B; Repr. 2 is rather indicated.

Executive summary:

A literature review of sodium borate and boric acid showed that these borates interfere with reproduction, mainly by effects on the gonads of the males. Data does not suffice for classification as Repr. 1B; Repr. 2 is rather indicated.