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EC number: 234-371-7 | CAS number: 11128-29-3
- 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
Developmental toxicity / teratogenicity
Administrative data
- Endpoint:
- developmental toxicity
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- No data
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see justification for type of information
- Justification for type of information:
- Meets acceptable scientific standards with acceptable restrictions. Read-across is justified on the following basis: The family of zinc borates that include Zinc Borate 500, Zinc Borate 2335 and Zinc Borate 415 (also known as Zinc Borate 411). Zinc borate 500 is anhydrous Zinc Borate 2335 and Zinc Borate 415 has different zinc to boron ratio. Zinc borate 2335 (in common with other zinc borates such as Zinc borate 415 and 500) breaks down to Zinc Hydroxide (via Zinc oxide) and Boric Acid, therefore the family of zinc borates shares the same toxicological properties. Zinc borates are sparingly soluble salts. Hydrolysis under high dilution conditions leads to zinc hydroxide via zinc oxide and boric acid formation. Zinc hydroxide and zinc oxide solubility is low under neutral and basic conditions. This leads to a situation where zinc borate hydrolyses to zinc hydroxide, zinc oxide and boric acid at neutral pH quicker than it solubilises. Therefore, it can be assumed that at physiological conditions and neutral and lower pH zinc borate will be hydrolysed to boric acid, zinc oxide and zinc hydroxide. Hydrolysis and the rate of hydrolysis depend on the initial loading and time. At a loading of 5% (5g/100ml) zinc borate hydrolysis equilibrium may take 1-2 months, while at 1 g/l hydrolysis is complete after 5 days. At 50 mg/l hydrolysis and solubility is complete (Schubert et al., 2003). At pH 4 hydrolysis is complete. Zinc Borate 2335 breaks down as follows: 2ZnO • 3B2O3 •3.5H2O + 3.5H2O + 4H+ ↔ 6H3BO3 + 2Zn2+ 2Zn2+ + 4OH- ↔ 2Zn(OH)2 ____________________________________________________________ Overall equation 2ZnO • 3B2O3 •3.5H2O + 7.5H2O ↔ 2Zn(OH)2 + 6H3BO3 The relative zinc oxide and boric oxide % are as follows: Zinc borate 2335:zinc oxide = 37.45% (30.09% Zn) B2O3 = 48.05% (14.94% B) Water 14.5% Zinc borate 415: zinc oxide = 78.79%; (63.31% Zn) B2O3 = 16.85% (5.23% B) Water 4.36% Zinc borate, anhydrous: Zinc oxide = 45 % B2O3= 55% (17.1 % B)
Data source
Reference
- Reference Type:
- publication
- Title:
- Benchmark dose analysis of developmental toxicity in rats exposed to boric acid.
- Author:
- Allen, B.C., Strong, P.L., Price, C.J., Hubbard, S.A. & Daston, G.P.
- Year:
- 1 996
- Bibliographic source:
- Fundamental and Applied Toxicology 32: 194 - 204.
Materials and methods
Test guideline
- Qualifier:
- no guideline required
- Principles of method if other than guideline:
- Developmental toxicity risk assessment has typically relied on the estimation of reference doses or reference concentrations based on the use of NOAELs divided by uncertainty factors. The benchmark dose (BMD) approach has been proposed as an alternative basis for reference value calculations. In this analysis of the developmental toxicity observed in rats exposed to boric acid in their diet, BMD analyses have been conducted using two existing studies. By considering various endpoints (rib XIII effects, variations of the first lumbar rib) and fetal weight changes and various modelling approaches for those endpoints, the best approach for incorporating all of the information available from the studies was determined. In this case, the approach involved combining data from two studies which were similarly designed and were conducted in the same laboratory to calculate BMDs that were more accurate and more precise than from either study alone.
- GLP compliance:
- not specified
- Remarks:
- not applicable (it is a publication)
- Limit test:
- 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
Constituent 1
Test animals
- Species:
- rat
- Strain:
- Sprague-Dawley
Administration / exposure
- Route of administration:
- oral: feed
- Vehicle:
- not specified
- Analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- 20 days
- Frequency of treatment:
- continuously in diet
Doses / concentrationsopen allclose all
- Dose / conc.:
- 0 mg/kg bw/day (nominal)
- Remarks:
- (Heindel et al., 1992) - Study A
- Dose / conc.:
- 78 mg/kg bw/day (nominal)
- Remarks:
- (Heindel et al., 1992) - Study A
- Dose / conc.:
- 163 mg/kg bw/day (nominal)
- Remarks:
- (Heindel et al., 1992) - Study A
- Dose / conc.:
- 330 mg/kg bw/day (nominal)
- Remarks:
- (Heindel et al., 1992) - Study A
- Dose / conc.:
- 539 mg/kg bw/day (nominal)
- Remarks:
- (Heindel et al., 1992) - Study A
- Dose / conc.:
- 0 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- Dose / conc.:
- 19 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- Dose / conc.:
- 36 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- Dose / conc.:
- 55 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- Dose / conc.:
- 76 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- Dose / conc.:
- 143 mg/kg bw/day (nominal)
- Remarks:
- (Price et al., 1994, 1995) - Study B
- No. of animals per sex per dose:
- - 29 time-mated females/group (study A);
- 60 time-mated females/group (study B). - Control animals:
- yes, plain diet
- Details on study design:
- The studies consist of two phases:
- Phase I: developmental toxicity termination on gd 20;
- Phase II: Postnatal recovery termination on pnd 21 (has not been considered in the analyses dicussed in the publication)
Results and discussion
Results: maternal animals
Effect levels (maternal animals)
open allclose all
- Dose descriptor:
- BMD:
- Effect level:
- 59 mg/kg bw/day
- Based on:
- test mat.
- Basis for effect level:
- other: developmental toxicity
- Remarks on result:
- other: Decreased foetal body weight provided the best basis for BMD calculations. The benchmark dose is defined as the 95% lower bound on the dose corresponding to a 5% decrease in the mean fetal weight (BMDL05).
- Remarks:
- Results are based on the studies of Heindel et al. (1992), Price, Marr & Myers (1994) and Price et al. (1996) (cited in Allen et al., 1996).
- Dose descriptor:
- BMD:
- Effect level:
- 10.3 mg/kg bw/day
- Based on:
- element
- Basis for effect level:
- other: developmental toxicity
- Remarks on result:
- other: Results are based on the studies of Heindel et al. (1992), Price, Marr & Myers (1994) and Price et al. (1996) (cited in Allen et al., 1996).
Results (fetuses)
- Details on embryotoxic / teratogenic effects:
- Embryotoxic / teratogenic effects:yes
Details on embryotoxic / teratogenic effects:
- incidence of total malformations, enlarged lateral ventricles in the brain, agenesis or shortening of rib XIII , and variations of the first lumbar rib, as well as decreased fetal weights.
Effect levels (fetuses)
open allclose all
- Dose descriptor:
- BMD:
- Effect level:
- 59 mg/kg bw/day
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: developmental toxicity
- Remarks on result:
- other: Decreased foetal body weight provided the best basis for BMD calculations. The benchmark dose is defined as the 95% lower bound on the dose corresponding to a 5% decrease in the mean fetal weight (BMDL05).
- Remarks:
- Results are based on the studies of Heindel et al. (1992), Price, Marr & Myers (1994) and Price et al. (1996) (cited in Allen et al., 1996).
- Dose descriptor:
- BMD:
- Effect level:
- 10.3 mg/kg bw/day
- Based on:
- element
- Sex:
- male/female
- Basis for effect level:
- other: developmental toxicity
- Remarks on result:
- other: Results are based on the studies of Heindel et al. (1992), Price, Marr & Myers (1994) and Price et al. (1996) (cited in Allen et al., 1996).
Fetal abnormalities
- Abnormalities:
- not specified
Overall developmental toxicity
- Developmental effects observed:
- not specified
Applicant's summary and conclusion
- Conclusions:
- Developmental toxicity risk assessment has typically relied on the estimation of reference doses or reference concentrations based on the ues of NOAELs divided by uncertainty factors. The benchmark dose approach has been proposed as an alternative basis for reference value calculations. In the analysis presented of the developmental toxicity of rats exposed to boric acid in their diet, BMD analyses have been conducted using two existing studies. By considering various endpounts (rib XIII effects, variations of the first lumbar rib) and fetal weight changes and various modelling approachesfor those endpoints the best approach for incorporating all the information was determined. Decreased foetal body weight provided the best basis for BMD calculations. The BMD was calculated as 59 mg/kg bw/day.
- Executive summary:
A benchmark dose developed by Allen et al. (1996) was based on the studies of Heindel et al. (1992), Price, Marr & Myers (1994) and Price et al. (1996). The benchmark dose is defined as the 95 % lower bound on the dose corresponding to a 5 % decrease in the mean fetal weight (BMDL05). The BMDL05of 10.3 mg/kg body weight per day as boron is close to the Price et al. (1996) NOAEL of 9.6 mg/kg body weight per day.
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