Registration Dossier
Registration Dossier
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EC number: 237-222-4 | CAS number: 13701-59-2
- 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
Toxicological Summary
- Administrative data
- Workers - Hazard via inhalation route
- Workers - Hazard via dermal route
- Workers - Hazard for the eyes
- Additional information - workers
- General Population - Hazard via inhalation route
- General Population - Hazard via dermal route
- General Population - Hazard via oral route
- General Population - Hazard for the eyes
- Additional information - General Population
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 2.5 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 25
- Dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 61.7 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 70 mg/kg bw/d is corrected for breathing rate and activity level (/0.38 *0.67), the extent of oral absorption (50%) and inhalation absorption (100%)
- AF for dose response relationship:
- 1
- Justification:
- The substance is classified as a reproductive toxin based on testicular effects seen in male rats at the highest dietary concentration of 10000 ppm (~700 mg/kg bw/d) in the 90-day toxicity study. No testicular effects were observed at the intermediate dose level of 5000 ppm (~350 mg/kg bw/d) and an overall NOAEL of 1000 ppm (70 mg/kg bw/d) was derived for this study based on bodyweight effects. The NOAEL of 70 mg/kg bw/d for this study is used as the starting point for the derivation of long-term DNEL values; the use of this dose level represents additional safety factors of 5 and 10 over the NOAEL and LOAEL (respectively) for testicular toxicity seen in the 90-day study and is considered to be an adequately conservative approach for the protection of workers. The use of an additional assessment factor is therefore not proposed.
- AF for differences in duration of exposure:
- 2
- Justification:
- Extrapolation from sub-chronic study to chronic exposure
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- No adjustment for allometry required, addressed in the calculation to determine inhalation dose descriptor
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 5
- Justification:
- Default value (worker)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 3.5 mg/m³
- Most sensitive endpoint:
- neurotoxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 12.5
- Dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 44.1 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 50 mg/kg bw/d is corrected for breathing rate and activity level (1/0.38 *0.67), the extent of oral absorption (50%) and inhalation absorption (100%)
- AF for dose response relationship:
- 1
- Justification:
- Default value
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- No adjustment for allometry required, addressed in the calculation to determine inhalation dose descriptor
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 5
- Justification:
- Default value (worker)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 7 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 100
- Dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 700 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 70 mg/kg bw/d is corrected for the extent of oral absorption (50%) and dermal absorption (5%)
- AF for dose response relationship:
- 1
- Justification:
- The substance is classified as a reproductive toxin based on testicular effects seen in male rats at the highest dietary concentration of 10000 ppm (~700 mg/kg bw/d) in the 90-day toxicity study. No testicular effects were observed at the intermediate dose level of 5000 ppm (~350 mg/kg bw/d) and an overall NOAEL of 1000 ppm (70 mg/kg bw/d) was derived for this study based on bodyweight effects. The NOAEL of 70 mg/kg bw/d for this study is used as the starting point for the derivation of long-term DNEL values; the use of this dose level represents additional safety factors of 5 and 10 over the NOAEL and LOAEL (respectively) for testicular toxicity seen in the 90-day study and is considered to be an adequately conservative approach for the protection of workers. The use of an additional assessment factor is therefore not proposed.
- AF for differences in duration of exposure:
- 2
- Justification:
- Extrapolation from sub-chronic to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (rat study)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 5
- Justification:
- Default value (worker)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 10 mg/kg bw/day
- Most sensitive endpoint:
- neurotoxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 50
- Dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 500 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 50 mg/kg bw/d is corrected for the extent of oral absorption (50%) and dermal absorption (5%)
- AF for dose response relationship:
- 1
- Justification:
- Default value
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (rat study)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 5
- Justification:
- Default value (worker)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
Workers - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- no hazard identified
Additional information - workers
For repeated exposure, the critical study for BMBF is the 90-day rat oral toxicity which identifies a NOAEL of 70 mg/kg bw/d, based on bodyweight effects at the next highest dose level of 350 mg/kg bw/d. The highest dose level in this study (700 mg/kg bw/d) showed effects on the reproductive tract of male rats (testicular and epididymal spermatogenesis). This finding is consistent with those seen with other boron-containing substances such as boric acid and boric oxide. Findings with BMBF are also seen at dose levels comparable (following correction for boron content) to dose levels of boric acid and boric oxide also causing testicular effects. The dose level of 700 mg/kg bw/d BMBF is equivalent to a dose level of approximately 63 mg/kg bw/d boron; findings in a 90-day study with boric acid are seen at a dose level of 334 mg/kg bw/d, equivalent to approximately 59 mg/kg bw/d boron. A reproductive toxicity study performed with boric acid at the same dose level resulted in a marked reduction in fertility due to male sterility. It is a reasonable assumption, therefore, that the administration of BMBF would cause comparable reproductive effects. Testing of BMBF for reproductive toxicity is therefore not proposed. The substance is proposed to be classified for reproductive toxicity in Category 1B in line with boric acid and boric oxide. An SCL of 10.7% is proposed, in line with the SCL values agreed for boric acid (5.5%) and boric oxide (3.1%) and taking into account the lower boron content of BMBF.
For acute exposure, the critical study for BMBF is the acute neurotoxicity study in the rat, which identifies a NOAEL of 50 mg/kg bw based on behavioural effects apparent at dose levels of 100 mg/kg bw and higher.
The relevant starting points for the derivation of DNELs for BMBF are the NOAEL of 70 mg/kg bw/d from the 90-day rat study and the NOAEL of 50 mg/kg bw/d derived from the acute neurotoxicity study.
Inhalation DNELs
Systemic DNELs
A long-term inhalation systemic DNEL is derived from the NOAEL of 70 mg/kg bw/d from the 90-day rat study. A corrected (inhalation) starting point of 61.7 mg/m3derived, taking into account breathing rate (1/0.38*0.67) and the relative extent of oral (50%) and inhalation absorption (100%).
Applying assessment factors of 1 (for dose-response relationship), 2 (for duration of exposure), 1 (for allometric scaling), 2.5 (for other interspecies differences), 5 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 25. Applying the assessment factor of 25 to the corrected starting point gives a DNEL of 2.5 mg/m3.
BMBF is classified for reproductive toxicity based on effects seen in the 90-day study at a dose level of 700 mg/kg bw/d; the NOAEL for this effect is 350 mg/kg bw/d, whereas the overall study NOAEL is 70 mg/kg bw/d. Derivation of the DNEL from the overall study NOAEL therefore represents additional margins of safety of 5 and 10 over the NOAEL and LOAEL for testicular effects, respectively. This approach is considered to be adequately conservative for the protection of workers from the reproductive toxicity of BMBF. The use of additional assessment factors is therefore not proposed.
A short-term inhalation systemic DNEL is derived from the NOAEL of 50 mg/kg bw/d from the acute neurotoxicity rat study. A corrected (inhalation) starting point of 44.1 mg/m3is derived, taking into account breathing rate (1/0.38*0.67), and the relative extent of oral absorption (50%) and inhalation absorption (100%).
Applying assessment factors of 1 (for dose-response relationship), 1 (for allometric scaling), 2.5 (for other interspecies differences), 5 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 12.5. Applying the assessment factor of 12.5 to the corrected starting point gives a DNEL of 3.5 mg/m3.
Local inhalation DNEL values are not derived in the absence of any identified hazard.
Dermal DNELs
Systemic DNELs
A long-term dermal systemic DNEL is derived from the NOAEL of 70 mg/kg bw/d from the 90-day rat study. A corrected (dermal) starting point of 700 mg/kg bw/d derived taking into account the relative extent of oral absorption (50%) and dermal absorption (5%).
Applying assessment factors of 1 (for dose-response relationship), 2 (for duration of exposure), 4 (for allometric scaling), 2.5 (for other interspecies differences), 5 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 100. Applying the assessment factor of 100 to the corrected starting point gives a DNEL of 7 mg/kg bw/d. BMBF is classified for reproductive toxicity based on effects seen in the 90-day study at a dose level of 700 mg/kg bw/d; the NOAEL for this effect is 350 mg/kg bw/d, whereas the overall study NOAEL is 70 mg/kg bw/d. Derivation of the DNEL from the overall study NOAEL therefore represents additional margins of safety of 5 and 10 over the NOAEL and LOAEL for testicular effects, respectively. This approach is considered to be adequately conservative for the protection of workers from the reproductive toxicity of BMBF. The use of additional assessment factors is therefore not proposed.
A short-term dermal systemic DNEL is derived from the NOAEL of 50 mg/kg bw/d from the acute neurotoxicity rat study. A corrected (dermal) starting point of 500 mg/kg bw/d derived taking into account the relative extent of oral absorption (50%) and dermal absorption (5%).
Applying assessment factors of 1 (for dose-response relationship), 4 (for allometric scaling), 2.5 (for other interspecies differences), 5 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 50. Applying the assessment factor of 50 to the corrected starting point gives a DNEL of 10 mg/kg bw/d.
Local dermal DNELs are not derived in the absence of any hazard.
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.6 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 50
- Dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 30.4 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 70 mg/kg bw/d is corrected for breathing rate (/1.15), the extent of oral absorption (50%) and inhalation absorption (100%)
- AF for dose response relationship:
- 1
- Justification:
- The substance is classified as a reproductive toxin based on testicular effects seen in male rats at the highest dietary concentration of 10000 ppm (~700 mg/kg bw/d) in the 90-day toxicity study. No testicular effects were observed at the intermediate dose level of 5000 ppm (~350 mg/kg bw/d) and an overall NOAEL of 1000 ppm (70 mg/kg bw/d) was derived for this study based on bodyweight effects. The NOAEL of 70 mg/kg bw/d for this study is used as the starting point for the derivation of long-term DNEL values; the use of this dose level represents additional safety factors of 5 and 10 over the NOAEL and LOAEL (respectively) for testicular toxicity seen in the 90-day study and is considered to be an adequately conservative approach for the protection of the general population. The use of an additional assessment factor is therefore not proposed.
- AF for differences in duration of exposure:
- 2
- Justification:
- Extrapolation from sub-chronic to chronic exposure
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- No adjustment for allometry required, addressed in the calculation to determine inhalation dose descriptor
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.9 mg/m³
- Most sensitive endpoint:
- neurotoxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 25
- Dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 21.7 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 50 mg/kg bw/d is corrected for breathing rate (/1.15), the extent of oral absorption (50%) and inhalation absorption (100%)
- AF for dose response relationship:
- 1
- Justification:
- Default value
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- No adjustment for allometry required, addressed in the calculation to determine inhalation dose descriptor
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 3.5 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 200
- Dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 700 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 70 mg/kg bw/d is corrected for the extent of oral absorption (50%) and dermal absorption (5%)
- AF for dose response relationship:
- 1
- Justification:
- The substance is classified as a reproductive toxin based on testicular effects seen in male rats at the highest dietary concentration of 10000 ppm (~700 mg/kg bw/d) in the 90-day toxicity study. No testicular effects were observed at the intermediate dose level of 5000 ppm (~350 mg/kg bw/d) and an overall NOAEL of 1000 ppm (70 mg/kg bw/d) was derived for this study based on bodyweight effects. The NOAEL of 70 mg/kg bw/d for this study is used as the starting point for the derivation of long-term DNEL values; the use of this dose level represents additional safety factors of 5 and 10 over the NOAEL and LOAEL (respectively) for testicular toxicity seen in the 90-day study and is considered to be an adequately conservative approach for the protection of the general population. The use of an additional assessment factor is therefore not proposed.
- AF for differences in duration of exposure:
- 2
- Justification:
- Extrapolation from subchronic to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (rat study)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 5 mg/kg bw/day
- Most sensitive endpoint:
- neurotoxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 100
- Dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 500 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- The oral NOAEL of 50 mg/kg bw/d is corrected for the extent of oral absorption (50%) and dermal absorption (5%)
- AF for dose response relationship:
- 1
- Justification:
- Default value
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (rat study)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
General Population - Hazard via oral route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.4 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 200
- Dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 70 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- Not required - oral study used as starting point
- AF for dose response relationship:
- 1
- Justification:
- The substance is classified as a reproductive toxin based on testicular effects seen in male rats at the highest dietary concentration of 10000 ppm (~700 mg/kg bw/d) in the 90-day toxicity study. No testicular effects were observed at the intermediate dose level of 5000 ppm (~350 mg/kg bw/d) and an overall NOAEL of 1000 ppm (70 mg/kg bw/d) was derived for this study based on bodyweight effects. The NOAEL of 70 mg/kg bw/d for this study is used as the starting point for the derivation of long-term DNEL values; the use of this dose level represents additional safety factors of 5 and 10 over the NOAEL and LOAEL (respectively) for testicular toxicity seen in the 90-day study and is considered to be an adequately conservative approach for the protection of the general population. The use of an additional assessment factor is therefore not proposed.
- AF for differences in duration of exposure:
- 2
- Justification:
- Extrapolation from subchronic to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (Rat)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 0.5 mg/kg bw/day
- Most sensitive endpoint:
- neurotoxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 100
- Dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 50 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- Not required - oral study used as starting point
- AF for dose response relationship:
- 1
- Justification:
- Default value
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Default value (rat study)
- AF for other interspecies differences:
- 2.5
- Justification:
- Default value
- AF for intraspecies differences:
- 10
- Justification:
- Default value (general population)
- AF for the quality of the whole database:
- 1
- Justification:
- Default value
- AF for remaining uncertainties:
- 1
- Justification:
- Default value
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- no hazard identified
Additional information - General Population
For repeated exposure, the critical study for BMBF is the 90-day rat oral toxicity which identifies a NOAEL of 70 mg/kg bw/d, based on bodyweight effects at the next highest dose level of 350 mg/kg bw/d. The highest dose level in this study (700 mg/kg bw/d) showed effects on the reproductive tract of male rats (testicular and epididymal spermatogenesis). This finding is consistent with those seen with other boron-containing substances such as boric acid and boric oxide. Findings with BMBF are also seen at dose levels comparable (following correction for boron content) to dose levels of boric acid and boric oxide also causing testicular effects. The dose level of 700 mg/kg bw/d BMBF is equivalent to a dose level of approximately 63 mg/kg bw/d boron; findings in a 90-day study with boric acid are seen at a dose level of 334 mg/kg bw/d, equivalent to approximately 59 mg/kg bw/d boron. A reproductive toxicity study performed with boric acid at the same dose level resulted in a marked reduction in fertility due to male sterility. It is a reasonable assumption, therefore, that the administration of BMBF would cause comparable reproductive effects. Testing of BMBF for reproductive toxicity is therefore not proposed. The substance is proposed to be classified for reproductive toxicity in Category 1B in line with boric acid and boric oxide. An SCL of 10.7% is proposed, in line with the SCL values agreed for boric acid (5.5%) and boric oxide (3.1%) and taking into account the lower boron content of BMBF.
For acute exposure, the critical study for BMBF is the acute neurotoxicity study in the rat, which identifies a NOAEL of 50 mg/kg bw based on behavioural effects apparent at dose levels of 100 mg/kg bw and higher.
The relevant starting points for the derivation of DNELs for BMBF are the NOAEL of 70 mg/kg bw/d from the 90-day rat study and the NOAEL of 50 mg/kg bw/d derived from the acute neurotoxicity study.
Inhalation DNELs
Systemic DNELs
A long-term inhalation systemic DNEL is derived from the NOAEL of 70 mg/kg bw/d from the 90-day rat study. A corrected (inhalation) starting point of 30.4 mg/m3is derived, taking into account breathing rate (*1/1.15) and the relative extent of oral (50%) and inhalation absorption (100%).
Applying assessment factors of 1 (for dose-response relationship), 2 (for duration of exposure), 1 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 50. Applying the assessment factor of 50 to the corrected starting point gives a DNEL of 0.6 mg/m3.
BMBF is classified for reproductive toxicity based on effects seen in the 90-day study at a dose level of 700 mg/kg bw/d; the NOAEL for this effect is 350 mg/kg bw/d, whereas the overall study NOAEL is 70 mg/kg bw/d. Derivation of the DNEL from the overall study NOAEL therefore represents additional margins of safety of 5 and 10 over the NOAEL and LOAEL for testicular effects, respectively. This approach is considered to be adequately conservative for the protection of workers from the reproductive toxicity of BMBF. The use of additional assessment factors is therefore not proposed.
A short-term inhalation systemic DNEL is derived from the NOAEL of 50 mg/kg bw/d from the acute neurotoxicity rat study. A corrected (inhalation) starting point of 21.7 mg/m3is derived, taking into account breathing rate (*1/1.15), and the relative extent of oral absorption (50%) and inhalation absorption (100%).
Applying assessment factors of 1 (for dose-response relationship), 1 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 25. Applying the assessment factor of 25 to the corrected starting point gives a DNEL of 0.9 mg/m3.
Local inhalation DNEL values are not derived in the absence of any identified hazard.
Dermal DNELs
Systemic DNELs
A long-term dermal systemic DNEL is derived from the NOAEL of 70 mg/kg bw/d from the 90-day rat study. A corrected (dermal) starting point of 700 mg/kg bw/d derived taking into account the relative extent of oral absorption (50%) and dermal absorption (5%).
Applying assessment factors of 1 (for dose-response relationship), 2 (for duration of exposure), 4 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 200. Applying the assessment factor of 200 to the corrected starting point gives a DNEL of 3.5 mg/kg bw/d. BMBF is classified for reproductive toxicity based on effects seen in the 90-day study at a dose level of 700 mg/kg bw/d; the NOAEL for this effect is 350 mg/kg bw/d, whereas the overall study NOAEL is 70 mg/kg bw/d. Derivation of the DNEL from the overall study NOAEL therefore represents additional margins of safety of 5 and 10 over the NOAEL and LOAEL for testicular effects, respectively. This approach is considered to be adequately conservative for the protection of workers from the reproductive toxicity of BMBF. The use of additional assessment factors is therefore not proposed.
A short-term dermal systemic DNEL is derived from the NOAEL of 50 mg/kg bw/d from the acute neurotoxicity rat study. A corrected (dermal) starting point of 500 mg/kg bw/d derived taking into account the relative extent of oral absorption (50%) and dermal absorption (5%).
Applying assessment factors of 1 (for dose-response relationship), 4 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 100. Applying the assessment factor of 100 to the corrected starting point gives a DNEL of 5 mg/kg bw/d.
Local dermal DNELs are not derived in the absence of any hazard.
Oral DNELs
Systemic DNELs
A long-term oral systemic DNEL is derived from the NOAEL of 70 mg/kg bw/d from the 90-day rat study. Correction of the starting point is not required.
Applying assessment factors of 1 (for dose-response relationship), 2 (for duration of exposure), 4 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 200. Applying the assessment factor of 200 to the starting point gives a DNEL of 0.4 mg/kg bw/d. BMBF is classified for reproductive toxicity based on effects seen in the 90-day study at a dose level of 700 mg/kg bw/d; the NOAEL for this effect is 350 mg/kg bw/d, whereas the overall study NOAEL is 70 mg/kg bw/d. Derivation of the DNEL from the overall study NOAEL therefore represents additional margins of safety of 5 and 10 over the NOAEL and LOAEL for testicular effects, respectively. This approach is considered to be adequately conservative for the protection of workers from the reproductive toxicity of BMBF. The use of additional assessment factors is therefore not proposed.
A short-term oral systemic DNEL is derived from the NOAEL of 50 mg/kg bw/d from the acute neurotoxicity rat study. Correction of the starting point is not required.
Applying assessment factors of 1 (for dose-response relationship), 4 (for allometric scaling), 2.5 (for other interspecies differences), 10 (for intraspecies differences), 1 (for database quality) and 1 (for remaining uncertainties) results in an overall assessment factor of 100. Applying the assessment factor of 100 to the corrected starting point gives a DNEL of 0.7 mg/kg bw/d.
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