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The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
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EC number: 231-113-5 | CAS number: 7440-03-1
- 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:
- 23.5 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):
- 75
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 1 763 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- NOAECcorr = NOAELoral*(1/0.38 m³/kg bw/day)*(ABSinh-rat/ABSinh-human)*(6.7 m³ (8h)/10 m³ (8h)) = 1000 mg/kg bw/day * 6.7 / (10 x 0.38) = 1763 mg/m3
- AF for dose response relationship:
- 1
- Justification:
- NOEL was used as starting point
- AF for differences in duration of exposure:
- 6
- Justification:
- Extrapolation subacute to chronic exposure
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- AF not needed for inhalation route.
- AF for other interspecies differences:
- 2.5
- Justification:
- According to ECHA guidance document R8
- AF for intraspecies differences:
- 5
- Justification:
- For workers
- AF for the quality of the whole database:
- 1
- Justification:
- The whole database indicates no systemic toxicity of niobium and thus the data base is conclusive and of good quality.
- AF for remaining uncertainties:
- 1
- Justification:
- Although the analogue approach may present a remaining uncertainty, this is already covered by using a NOEL instead of a NOAEL as starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
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:
- 3.3 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):
- 300
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 1 000 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- Dermal NOAEL=NOAELoral*(ABSoral-rat/ABSdermal-human) = (1000 mg/kg bw/day)*(1/1) = 1000 mg/kg bw/day.
- AF for dose response relationship:
- 1
- Justification:
- NOEL was used as starting point
- AF for differences in duration of exposure:
- 6
- Justification:
- Extrapolation subacute to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- According to ECHA guidance document R8
- AF for other interspecies differences:
- 2.5
- Justification:
- According to ECHA guidance document R8
- AF for intraspecies differences:
- 5
- Justification:
- For workers
- AF for the quality of the whole database:
- 1
- Justification:
- The whole database indicates no systemic toxicity of niobium and thus the data base is conclusive and of good quality.
- AF for remaining uncertainties:
- 1
- Justification:
- Although the analogue approach may present a remaining uncertainty, this is already covered by using a NOEL instead of a NOAEL as starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
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
Niobium metal is not bioavailable via any foreseeable route of exposure. This entails a lack of toxicological hazards. Toxicological threshold values proposed for niobium metal are only achieved to support the conclusion that exposure to niobium is not significant.
Reliable OECD Guideline422 studies with the alloy ferro niobium and with the read-across substance diniobium pentoxide are available. Neither adverse systemic effects nor adverse findings in organs and tissues related to oral (gavage) treatment in male and female rats up to the limit dose of 1000 mg/kg bw/d (Takawale, 2010 and Rudragowda, 2010, respectively) were observed. Consequently the NOAEL was > 1000 mg/kg bw/d. For a detailed rational for read-across please refer to the respective subsection and the analogue justification attached in IUCLID section 13.
Conversion of oral NOAEL to inhalatory NAEC
Since there is no dose descriptor for every exposure route, the dose descriptor was converted into a correct starting point by route-to-route extrapolation based on the ECHA guidance document "Guidance on information requirements and chemical safety assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health", November 2012.
The conversion of an oral NOAEL (>1000 mg/kg bw/d) into an inhalatory NAEC is performed using the following equations; for workers the resulting concentration needs to be additionally corrected for the difference between basal caloric demand and caloric demand under light activity:
Corrected inhalatory NAEC = oral NOAEL x1/sRVratx ABSoral-rat/ABSinh-humanxsRVhuman/wRV
= oral NOAEL x 1/0.38m³/kg bw x 1 x 6.7 m³/10 m³
sRV: standard respiratory volume, ABS: absorption, wRV: worker respiratory volume
Thus, the corrected starting point for inhalation route was 1000 * 6.7 / (10 x 0.38) = 1763 mg/m3
DNEL derivation using the inhalatory NAEC
In the ECHA Guidance a factor of 2 is suggested for the extrapolation from oral to inhalation absorption. On the contrary, the Technical guidance document on risk assessment in support of Commission directive 93/67/EEC, 2003 appendix IV A and B gives a number of physico-chemical properties that normally determine oral, inhalation and dermal absorption. These parameters include molecular weight, log Kow, pKa values and for inhalation also particle size distribution, vapour pressure etc.
It is assumed that the absorption rate of Niobium metal via either route is negligible (<< 1%, see IUCLID section 7.1) as the substance is insoluble under physiological conditions. Therefore, absorption is limited to dissolution and equal absorption was assumed when extrapolating from oral to inhalation route. Thus, the factor of 2 is considered to be not relevant for niobium when extrapolating from oral to inhalation route. A factor of 6 for the differences in exposure duration was applied. The NOAEL of the sub-acute study is extrapolated to a chronic NOAEL. Factors applied for interspecies differences (2.5) and intraspecies differences (5) were applied according to ECHA guidance document; Chapter R.8. The whole database indicates no systemic toxicity of niobium and the data base is conclusive and of good quality. Additionally a NOEL was used as starting point. Thus no further AF were deemed necessary.
Thus, the inhalatory DNEL is calculated to be 23.5 mg/m3.
Conversion of oral NOAEL to dermal NAEL for systemic toxicity
No difference in absorption between routes is expected.
Thus, the corrected starting point for dermal route was 1000 mg/kg bw/d.
DNEL derivation of dermal long-term systemic effects
A factor of 6 for the differences in exposure duration was applied. The NOAEL of the sub-acute study is extrapolated to a chronic NOAEL. Factors applied for allometric scaling (4), interspecies differences (2.5) and intraspecies differences (5) were applied according to ECHA guidance document; Chapter R.8. The whole database indicates no systemic toxicity of niobium and the data base is conclusive and of good quality. Additionally a NOEL was used as starting point. Thus no further AF were deemed necessary.
Thus, the dermal systemic DNEL is calculated to be 3.3 mg/kg bw/d.
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 5.8 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):
- 150
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 869.6 mg/m³
- Explanation for the modification of the dose descriptor starting point:
- NOAECcorr = NOAELoral / (ABSinh-rat/ABSinh-human) = 1000 mg/kg bw/day / 1.15 m³/kg bw = 869.6 mg/m³
- AF for dose response relationship:
- 1
- Justification:
- NOEL was used as starting point
- AF for differences in duration of exposure:
- 6
- Justification:
- Extrapolation subacute to chronic exposure
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- AF not needed for inhalation route
- AF for other interspecies differences:
- 2.5
- Justification:
- According to ECHA guidance document R8
- AF for intraspecies differences:
- 10
- Justification:
- For general population
- AF for the quality of the whole database:
- 1
- Justification:
- The whole database indicates no systemic toxicity of niobium and thus the data base is conclusive and of good quality.
- AF for remaining uncertainties:
- 1
- Justification:
- Although the analogue approach may present a remaining uncertainty, this is already covered by using a NOEL instead of a NOAEL as starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
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:
- 1.67 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):
- 600
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 1 000 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- Dermal NOAEL=NOAELoral*(ABSoral-rat/ABSdermal-human) = (1000 mg/kg bw/day)*(1/1) = 1000 mg/kg bw/day.
- AF for dose response relationship:
- 1
- Justification:
- NOEL was used as starting point
- AF for differences in duration of exposure:
- 6
- Justification:
- Extrapolation subacute to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- According to ECHA guidance document R8
- AF for other interspecies differences:
- 2.5
- Justification:
- According to ECHA guidance document R8
- AF for intraspecies differences:
- 10
- Justification:
- For general population
- AF for the quality of the whole database:
- 1
- Justification:
- The whole database indicates no systemic toxicity of niobium and thus the data base is conclusive and of good quality.
- AF for remaining uncertainties:
- 1
- Justification:
- Although the analogue approach may present a remaining uncertainty, this is already covered by using a NOEL instead of a NOAEL as starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
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:
- 1.67 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):
- 600
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 1 000 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
- Not necessary
- AF for dose response relationship:
- 1
- Justification:
- NOEL was used as starting point
- AF for differences in duration of exposure:
- 6
- Justification:
- Extrapolation subacute to chronic exposure
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- According to ECHA guidance document R8
- AF for other interspecies differences:
- 2.5
- Justification:
- According to ECHA guidance document R8
- AF for intraspecies differences:
- 10
- Justification:
- For general population
- AF for the quality of the whole database:
- 1
- Justification:
- The whole database indicates no systemic toxicity of niobium and thus the data base is conclusive and of good quality.
- AF for remaining uncertainties:
- 1
- Justification:
- Although the analogue approach may present a remaining uncertainty, this is already covered by using a NOEL instead of a NOAEL as starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- no hazard identified
Additional information - General Population
Niobium is not bioavailable via any foreseeable route of exposure. This entails a lack of toxicological hazards. Toxicological threshold values proposed for niobium are only achieved to support the conclusion that exposure to niobium is not significant.
Reliable OECD Guideline 422 studies with the alloy ferro niobium and with the read-across substance diniobium pentoxide are available. Neither adverse systemic effects nor adverse findings in organs and tissues related to oral (gavage) treatment in male and female rats up to the limit dose of 1000 mg/kg bw/d (Takawale, 2010 and Rudragowda, 2010, respectively) were observed. Consequently the NOAEL was > 1000 mg/kg bw/d. For a detailed rational for read-across please refer to the respective subsection and the analogue justification attached in IUCLID section 13.
Conversion of oral NOAEL to inhalatory NAEC
Since there is no dose descriptor for every exposure route, the dose descriptor was converted into a correct starting point by route-to-route extrapolation based on the ECHA guidance document "Guidance on information requirements and chemical safety assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health", November 2012.
The conversion of an oral NOAEL (>1000 mg/kg bw/d) into an inhalatory NAEC is performed using the following equations; for general population the resulting concentration needs to be additionally corrected for the difference between basal caloric demand and caloric demand under light activity:
Corrected inhalatory NAEC = oral NOAEL * ABSinh-rat/ABSinh-human
= oral NOAEL / 1.15 m³/kg bw
ABS: absorption
Thus, the corrected starting point for inhalation route was 1000 / 1.15 = 869.6 mg/m3
DNEL derivation using the inhalatory NAEC
In the ECHA Guidance a factor of 2 is suggested for the extrapolation from oral to inhalation absorption. On the contrary, the Technical guidance document on risk assessment in support of Commission directive 93/67/EEC, 2003 appendix IV A and B gives a number of physico-chemical properties that normally determine oral, inhalation and dermal absorption. These parameters include molecular weight, log Kow, pKa values and for inhalation also particle size distribution, vapour pressure etc.
It is assumed that the absorption rate of niobium via either route is negligible (<< 1%, see IUCLID section 7.1) as the substance is insoluble under physiological conditions. Therefore, absorption is limited to dissolution and equal absorption was assumed when extrapolating from oral to inhalation route. Thus, the factor of 2 is considered to be not relevant for niobium when extrapolating from oral to inhalation route. A factor of 6 for the differences in exposure duration was applied. The NOAEL of the sub-acute study is extrapolated to chronic a NOAEL. Factors applied for interspecies differences (2.5) and intraspecies differences (10) were applied according to ECHA guidance document; Chapter R.8. The whole database indicates no systemic toxicity of niobium and the data base is conclusive and of good quality. Additionally a NOEL was used as starting point. Thus no further AF were deemed necessary.
Thus, the inhalatory DNEL is calculated to be 5.8 mg/m3.
Conversion of oral NOAEL to dermal NAEL for systemic toxicity
No difference in absorption between routes is expected.
Thus, no correction of the starting point for dermal route was needed.
DNEL derivation of dermal long-term systemic effects
A factor of 6 for the differences in exposure duration was applied. The NOAEL of the sub-acute study is extrapolated to chronic a NOAEL. Factors applied for allometric scalling (4), i
nterspecies differences (2.5) and intraspecies differences (10) were applied according to ECHA guidance document; Chapter R.8.
The whole database indicates no systemic toxicity of niobium and the data base is conclusive and of good quality. Additionally a NOEL was used as starting point. Thus no further AF were deemed necessary.
Thus, the dermal systemic DNEL is calculated to be 1.67 mg/kg bw/d.
DNEL derivation of oral long-term systemic effects
A factor of 6 for the differences in exposure duration was applied. The NOAEL of the sub-acute study is extrapolated to chronic a NOAEL. Factors applied for allometric scalling (4), interspecies differences (2.5) and intraspecies differences (10) were applied according to ECHA guidance document; Chapter R.8. The whole database indicates no systemic toxicity of niobium and the data base is conclusive and of good quality. Additionally a NOEL was used as starting point. Thus no further AF were deemed necessary.
Thus, the oral systemic DNEL is calculated to be 1.67 mg/kg bw/d.
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