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EC number: 686-800-6 | CAS number: 12008-39-8
- 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
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
- Bioaccumulation potential:
- low bioaccumulation potential
- Absorption rate - oral (%):
- 100
- Absorption rate - dermal (%):
- 0.5
- Absorption rate - inhalation (%):
- 100
Additional information
There is little difference between animals and humans in absorption, distribution, and metabolism. A difference in renal clearance is the major determinant in the differences between animals and humans, with the renal clearance in rats approximately 3 times faster than in humans.
Boric acid is not metabolised in either animals or humans, owing to the high energy level required (523 kJ/mol) to break the B - O bond (Emsley, 1989). Other inorganic borates convert to boric acid at physiological pH in the aqueous layer overlying the mucosal surfaces prior to absorption. Most of the simple inorganic borates exist predominantly as undissociated boric acid in dilute aqueous solution at physiological and environmental pH, leading to the conclusion that the main species in the plasma of mammals is un-dissociated boric acid. Since other borates dissociate to form boric acid in aqueous solutions, they too can be considered to exist as undissociated boric acid under the same conditions. Additional support for this derives from studies in which more than 90 % of administered doses of inorganic borates are excreted in the urine as boric acid. Absorption of borates via the oral route is nearly 100 %. For the inhalation route also 100 % absorption is assumed as worst case scenario. Dermal absorption through intact skin is very low with a percent dose absorbed of 0.226 ± 0.125 in humans. Using the % dose absorbed plus standard deviation (SD) for boric acid, a dermal absorption for borates of 0.5 % (rounded from 0.45 %) can be assumed as a worse case estimate.
In the blood boric acid is the main species present and is not further metabolised. Boric acid is distributed rapidly and evenly through the body, with concentrations in bone 2 - 3 higher than in other tissues. Boric acid is excreted rapidly, with elimination half-lives of 1 h in the mouse, 3 h in the rat and < 27.8 h in humans, and has low potential for accumulation. Boric acid is mainly excreted in the urine.
Read Across
A number of these studies were conducted on an analogue substance. Read-across is justified on the following basis:
In aqueous solutions at physiological and acidic pH, low concentrations of simple inorganic borates such as boric acid B(OH)3, potassium pentaborate (K2B10O16.8H2O), potassium tetraborate (K2B4O7.4H2O), disodium tetraborate decahydrate (Na2B4O7.10H2O; borax), disodium tetraborate pentahydrate (Na2B4O7.5H2O; borax pentahydrate), boric oxide (B2O3), disodium octaborate tetrahydrate (Na2B8O13.4H2O), potassium octaborate (B8K2O13) and potassium octaborate tetrahydrate (B8K2O13.4H2O) will predominantly exist as undissociated boric acid. Above pH 9 the metaborate anion (B(OH)4-) becomes the main species in solution (WHO, 1998). This leads to the conclusion that the main species in the plasma of mammals and in the environment is undissociated boric acid. Since other borates dissociate to form boric acid in aqueous solutions, they too can be considered to exist as undissociated boric acid under the same conditions.
For comparative purposes, exposures to borates are often expressed in terms of boron (B) equivalents based on the fraction of boron in the source substance on a molecular weight basis. Some studies express dose in terms of B, whereas other studies express the dose in units of boric acid. Since the systemic effects and some of the local effects can be traced back to boric acid, results from one substance can be transferred to also evaluate the another substance on the basis of boron equivalents. Therefore data obtained from studies with these borates can be read across in the human health assessment for each individual substance. Conversion factors are given in the table below.
Substance |
Formula |
Conversion factor for equivalent dose of B (multiply by) |
|||
Boric acid |
H3BO3 |
0.1748 |
|||
Boric Oxide |
B2O3 |
0.311 |
|||
Disodium tetraborate anhydrous |
Na2B4O7 |
0.2149 |
|||
Disodium tetraborate pentahydrate |
Na2B4O7•5H2O |
0.1484 |
|||
Disodium tetraborate decahydrate |
Na2B4O7•10H2O |
0.1134 |
|||
Disodium octaborate tetrahydrate |
Na2B8O13·4H2O |
0.2096 |
|||
Sodium metaborate (anhydrous) |
NaBO2 |
0.1643 |
|||
Sodium metaborate (dihydrate) |
NaBO2·2H2O |
0.1062 |
|||
Sodium metaborate (tetrahydrate) |
NaBO2·4H2O |
0.0784 |
|||
Sodium pentaborate (anhydrous) |
NaB5O8 |
0.2636 |
|||
Sodium pentaborate (pentahydrate) |
NaB5O8∙5H2O |
0.1832 |
|||
Dipotassium tetraborate (anhydrous) | K2B4O7 | 0.185 | |||
Dipotassium tetraborate (tetrahydrate) | K2B4O7.4H2O | 0.1415 | |||
Potassium pentaborate (anhydrous) | B5KO8 | 0.244 | |||
Potassium pentaborate (tetrahydrate) | B5KO8.4H2O | 0.1843 | |||
Potassium octaborate (anhydrous) | B8K2O13 | 0.2321 | |||
Potassium octaborate (tetrahydrate) | B8K2O13.4H2O | 0.1945 |
References:
WHO. Guidelines for drinking-water quality, Addendum to Volume 1, 1998
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