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EC number: 237-262-2 | CAS number: 13709-94-9
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Skin irritation / corrosion
Administrative data
- Endpoint:
- skin irritation: in vivo
- Type of information:
- experimental study
- Remarks:
- publication / peer-reviewed report
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Remarks:
- peer-reviewed
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
see target record
Cross-reference
- Reason / purpose for cross-reference:
- read-across source
- Remarks:
- target record
Reference
- Endpoint:
- skin irritation: in vivo
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Remarks:
- publication / peer-reviewed report
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Remarks:
- peer-reviewed, read-across
- Justification for type of information:
- 1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Borates in general dissociate immediately upon contact with water and are converted rapidly into i.a. boric acid. This includes salts of boric acid (borates), metaboric acid (metaborates), hydrated borates (hydroborates) or borax. Boron compounds are highly soluble in water, and upon dissolving form essentially two species, undissociated boric acid (H3BO3) and borate anion (B(OH)4- [Soucek, Environmental Toxicology and Chemistry, Vol. 30, No. 8, pp. 1906–1914, 2011]. Orthoboric acid (Short: Boric acid, H3BO3) is a weak monobasic acid, which does not act as a proton donator but OH- acceptor (Lewis base) according to the following equilibrium:
B(OH)3 + 2 H2O ↔ B(OH)4- + H3O+ pKs = 9.2
Metaboric acid ((HBO2)n is formed during heating >90°C via intermolecular condensation while releasing a water molecule. Upon solubilisation in water, orthoboric acid is formed again. In diluted solutions practically only the monomeric H3BO3 are present [Riedel, Anorganische Chemie, de Gruyter, 1999]. A study by Zhu et al. [Zhu FY, Journal of Molecular Structure, Volume 1070, 24 July 2014, Pages 80-85] shows that the main borate species in aqueous KB(OH)4 solutions is B(OH)4−. This ion is in an equilibrium with H3BO3.
So in aqueous solutions at physiological and acidic pH, low concentrations of simple inorganic borates such as boric acid, disodium tetraborate decahydrate, disodium tetraborate pentahydrate, boric oxide and disodium octaborate tetrahydrate will predominantly exist as undissociated boric acid [WHO, Environmental Health Criteria 204, boron, World Health Organization, Geneva, 1998]. Also borax readily dissolves in water to form undissociated boric acid (H3BO3) and borate anion (B(OH)4-) [Soucek, 2011]. Most of the simple inorganic borates exist predominantly as undissociated boric acid in dilute aqueous solution at physiological pH [Hubbard SA, Biological Trace Element Research Vol. 66, 1998]. In aqueous solution, the metaborate ion is rapidly converted to the borate anion and the weakly dissociated boric acid by the sequential reactions shown by the following equations [Antia NJ, 1975, J. Fish. Res. Board Can. 32: 2487-2494]:
BO2- + 2 H2O → B(OH)4-
B(OH)4- + H3O+ ↔ B(OH)3 + 2 H2O
So if metaboric acid (resp. borates) is dissolved in water, orthoboric acid is formed [Riedel, 1999].
So summarizing, upon contact with water, potassium metaborate dissociates immediately into potassium and metaborate ions, whereas the latter is converted rapidly into boric acid.
As stated above, in diluted solutions and biologically relevant pH values, only undissociated boric acid is present, irrespective of which borate was dissolved in water, which so also applies to potassium metaborate. This is applicable for both ecotoxicity tests (usual limit concentration: 100 mg/l) as well as toxicological studies. Borates are readily absorbed orally in humans and animals [Hubbard, 1998], so the expected plasma levels are maximally as high as the applied dose, which still indicates that the boron species dissolved in plasma is H3BO3.
In consequence, data from boric acid and also all types of borates mentioned above, may be used to cover data gaps for potassium metaborate via read-across.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Target: Potassium metaborate, CAS 13709-94-9, EC 237-262-2, BKO2, MW = 81.9081 g/mol, SMILES [K+].[O-]B=O
Source: Boric acid / Orthoboric acid, CAS 10043-35-3, EC 233-139-2, H3BO3, MW = 61.83 g/mol, SMILES OB(O)O
Source: Borax / di-Sodium tetraborate decahydrate / sodium borate, CAS 1303-96-4, EC 603-411-9, Na2B4O7 *10H2O, MW = 381.365, SMILES (anhydrous) [Na+].[Na+].[O-]B(OB=O)OB([O-])OB=O
Source: Sodium tetraborate pentahydrate / Boron sodium oxide, pentahydrate, CAS 12179-04-3, EC 601-808-1, B4-O7.2Na.5H2-O, MW = 291.291 g/mol, SMILES B(=O)OB([O-])OB([O-])OB=O.O.O.O.O.O.[Na+].[Na+]
Source: Disodium octaborate tetrahydrate / Boron sodium oxide, tetrahydrate, CAS 12280-03-4, EC 602-894-3, B8Na2O13
Source: Sodium metaborate tetrahydrate / Boric acid, sodium salt, tetrahydrate, CAS 10555-76-7, EC 600-663-1
Source: Dipotassium tetraborate / boron potassium oxide, CAS 1332-77-0, EC 215-575-5, B4K2O7, MW = 233.4358, SMILES [K+].[K+].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-]
Source: Diammonium tetraborate tetrahydrate / azane;2-hydroxy-4-[(4-hydroxy-1,3,2,4-dioxadiboretan-2-yl)oxy]-1,3,2,4-dioxadiboretane;tetrahydrate, CAS 10135-84-9; 12228-87-4, B4H16N2O11, MW = 263.371, SMILES B1(OB(O1)OB2OB(O2)O)O.N.N.O.O.O.O
Source: Zinc borate, hydrate / dodecaboron tetrazinc docosaoxide heptahydrate / Boron zinc hydroxide oxide / hexaboron dizinc undecaoxide, CAS 138265-88-0, EC 235-804-2, B12Zn4(OH)14O15, MW = 425.7 g/mol
There are no impurities known in neither target nor source chemical(s) which may affect the feasibility of the read-across approach.
3. ANALOGUE APPROACH JUSTIFICATION
As obvious in detail from the available data matrix, all borates exhibit similar (eco-)toxicological properties.
With regard to ecotoxicity, all available studies on various borates on fish, invertebrates, and algae, both short and long term, consistently indicate that, recalculated from the molecular weight, Potassium metaborate does not need to be classified as aquatic toxic (acute and chronic) according to Regulation 1272/2008 and amendments.
Similarly, with regard to human-relevant endpoints, Potassium metaborate does not need to be classified as acutely toxic, as consistently indicated by various borates in also various species.
Both boric acid and borax do not trigger classification as skin sensitizing, no further study data is available, However, Sodium Borate and Boric Acid are used in cosmetics in various functions, and no sensitizing reactions induced by these cosmetic products have been reported.
Borax and Boric acid were similarly non-mutagenic in the Ames Test, and the non-genotoxic potential is further supported by a negative chromosome aberration test. Both Borax and Boric however gave in different species, although via partially species-specific mode of actions, indication that they interfere via a certain threshold with reproduction. Proof via human data is however not available.
Further, all borates chosen for read-across, incl. the registered substance itself, are highly soluble in water, and upon dissolving form essentially two species, undissociated boric acid (H3BO3) and borate anion (B(OH)4-. Hence, read-across is further based on common breakdown products.
So summarizing, read-across is justified via similar (eco-)toxicological effects and common breakdown products.
4. DATA MATRIX
See attachment - Reason / purpose for cross-reference:
- read-across source
- Qualifier:
- no guideline required
- Principles of method if other than guideline:
- Review of literature data
- GLP compliance:
- no
- Species:
- other: mainly rabbits, also guinea pigs
- Strain:
- not specified
- Remarks:
- sometimes "albino" is mentioned
- Details on test animals or test system and environmental conditions:
- no details available
- Type of coverage:
- occlusive
- Preparation of test site:
- other: various, intact, abraded, shaved
- Vehicle:
- other: various: water, undiluted, urine, bath preparation
- Controls:
- not specified
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- Boric Acid, rabbits
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 1.7
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild irritation
- Remarks:
- Ten ml of 5% boric acid (aqueous) were applied under occlusion to the clipped intact and abraded skin of six rabbits.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- Boric acid, guinea pigs
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 2.1
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild or moderate irritation
- Remarks:
- Ten ml of 5% boric acid (aqueous) were applied under occlusion to the clipped intact and abraded skin of six guinea pigs.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- sodium borate, rabbits
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 2
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild or moderate irritation
- Remarks:
- Ten ml of 5% Sodium Borate (aqueous) were applied under occlusion to the clipped intact and abraded skin of six rabbits.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- sodium borate, guinea pigs
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 1.4
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild irritation
- Remarks:
- Ten ml of 5% Sodium Borate (aqueous) were applied under occlusion to the clipped intact and abraded skin of six guinea pigs.
- Remarks on result:
- no indication of irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH of 3.81 (unadjusted),
- Remarks on result:
- other: moderate irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 7.38, adjusted with ammonium carbonate
- Remarks on result:
- other: mild irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 6.86, adjusted with ammonium carbonate
- Remarks on result:
- other: slight irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 7.87, adjusted with sodium hydroxide
- Remarks on result:
- other: marked irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 8.16, adjusted with ammonium carbonate and an ammonia solution
- Remarks on result:
- no indication of irritation
- Remarks:
- rabbits, 5% Boric Acid solution in freshly passed human urine
- Irritation parameter:
- erythema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: not available
- Irritation parameter:
- edema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: not available
- Interpretation of results:
- study cannot be used for classification
- Remarks:
- no erythema and edema scores given
- Conclusions:
- The present information was based on a literature review (peer-reviewed) of sodium borate and boric acid studies, which gave inconsistent results ranging from not irritating to irritating. Edema and erythema scores as indicated in Regulation 1272/2008, which are required for classification, are not given. Further, due to inconsistent results, no conclusion based on expert judgement can be drawn.
- Executive summary:
A literature review of sodium borate and boric acid showed that these borates induced none to irritating responses, no conclusion on classification can be drawn.
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:
- 1 983
- 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
Test material
- 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
- 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.
Constituent 1
Constituent 2
Test animals
- Species:
- other: mainly rabbits, also guinea pigs
- Strain:
- not specified
- Remarks:
- sometimes "albino" is mentioned
- Details on test animals or test system and environmental conditions:
- no details available
Test system
- Type of coverage:
- occlusive
- Preparation of test site:
- other: various, intact, abraded, shaved
- Vehicle:
- other: various: water, undiluted, urine, bath preparation
- Controls:
- not specified
Results and discussion
In vivo
Resultsopen allclose all
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- Boric Acid, rabbits
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 1.7
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild irritation
- Remarks:
- Ten ml of 5% boric acid (aqueous) were applied under occlusion to the clipped intact and abraded skin of six rabbits.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- Boric acid, guinea pigs
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 2.1
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild or moderate irritation
- Remarks:
- Ten ml of 5% boric acid (aqueous) were applied under occlusion to the clipped intact and abraded skin of six guinea pigs.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- sodium borate, rabbits
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 2
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild or moderate irritation
- Remarks:
- Ten ml of 5% Sodium Borate (aqueous) were applied under occlusion to the clipped intact and abraded skin of six rabbits.
- Irritation parameter:
- primary dermal irritation index (PDII)
- Remarks:
- sodium borate, guinea pigs
- Basis:
- mean
- Time point:
- other: 24&72h
- Score:
- 1.4
- Max. score:
- 8
- Reversibility:
- not specified
- Remarks on result:
- other: indicative of mild irritation
- Remarks:
- Ten ml of 5% Sodium Borate (aqueous) were applied under occlusion to the clipped intact and abraded skin of six guinea pigs.
- Remarks on result:
- no indication of irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH of 3.81 (unadjusted),
- Remarks on result:
- other: moderate irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 7.38, adjusted with ammonium carbonate
- Remarks on result:
- other: mild irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 6.86, adjusted with ammonium carbonate
- Remarks on result:
- other: slight irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 7.87, adjusted with sodium hydroxide
- Remarks on result:
- other: marked irritation
- Remarks:
- rabbits, 5% aqueous solutions of Boric Acid, pH 8.16, adjusted with ammonium carbonate and an ammonia solution
- Remarks on result:
- no indication of irritation
- Remarks:
- rabbits, 5% Boric Acid solution in freshly passed human urine
- Irritation parameter:
- erythema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: not available
- Irritation parameter:
- edema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: not available
Applicant's summary and conclusion
- Interpretation of results:
- study cannot be used for classification
- Remarks:
- no erythema and edema scores given
- Conclusions:
- The present information was based on a literature review (peer-reviewed) of sodium borate and boric acid studies, which gave inconsistent results ranging from not irritating to irritating. Edema and erythema scores as indicated in Regulation 1272/2008, which are required for classification, are not given. Further, due to inconsistent results, no conclusion based on expert judgement can be drawn.
- Executive summary:
A literature review of sodium borate and boric acid showed that these borates induced none to irritating responses, no conclusion on classification can be drawn.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.