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EC number: 231-130-8 | CAS number: 7440-21-3
- 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

Basic toxicokinetics
Administrative data
- Endpoint:
- basic toxicokinetics in vivo
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.
Cross-reference
- Reason / purpose for cross-reference:
- reference to same study
Data source
Reference
- Reference Type:
- publication
- Title:
- Pulmonary chemokine and mutagenic responses in rats after subchronic inhalation of amorphous and crystalline silica.
- Author:
- Johnston, C. J., K. E. Driscoll, et al.
- Year:
- 2 000
- Bibliographic source:
- Toxicol Sci.56(2): 405-13.
Materials and methods
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- In a subchronic inhalation study, rats were exposed 6h/d, 5 d/wk to 50 mg SiO2/m3 of hydrophilic pyrogenic silica (Aerosil® 200, MMAD 0.81 µm) or cristobalite (MMAD 1.3 μm) 3 mg/m3 for up to 13 weeks. The lung burden was measured after 6.5 and 13 weeks of exposure and after 3 and 8 months of recovery.
- GLP compliance:
- not specified
Test material
- Reference substance name:
- pyrogenic silica (amorphous silica)
- IUPAC Name:
- pyrogenic silica (amorphous silica)
- Reference substance name:
- cristobalite (crystalline silica)
- IUPAC Name:
- cristobalite (crystalline silica)
- Details on test material:
- - tradename of pyrogenic silica: Aerosil® 200 (hydrophilic)
- Mass Median Aerodynamic Diameter (MMAD): 0.81 µm for pyrogenic silica and 1.3 µm for cristobalite
Constituent 1
Constituent 2
- Radiolabelling:
- no
Test animals
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- Male Fisher rats weighting 200-250 g in the time of study initiation were kept in whole body chambers in compartmental 300 l horizontal laminar flow.
Administration / exposure
- Route of administration:
- inhalation: dust
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- TYPE OF INHALATION EXPOSURE: whole body
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Aerosols were generated by a screw-feed mechanism in combination with a venturi -type dust feeder - Duration and frequency of treatment / exposure:
- 6 hours/day, 5 days/week, up to 13 weeks
Doses / concentrations
- Remarks:
- Doses / Concentrations:
50 mg/m3 (pyrogenic silica) or 3 mg/m3 (cristobalite)
- No. of animals per sex per dose / concentration:
- 4 rats/group
- Control animals:
- yes, concurrent no treatment
- Positive control reference chemical:
- cristobalite
- Details on dosing and sampling:
- After 6.5 or 13 weeks of exposure or after 3 and 8 months recovery period rats were killed by pentobarbital followed by exsanguination of abdominal aorta and lung burdens of silica were analysed using emission spectroscopy at a wavelength of 251.612.
- Statistics:
- no
Results and discussion
Toxicokinetic / pharmacokinetic studies
- Details on distribution in tissues:
- Lung burden after 6.5 and 13 weeks exposure was 759 and 883 μg SiO2/lung for amorphous silica, respectively, and 336 and 819 μg SiO2/lung for crystalline silica. Lung burden of amorphous silica reduced rapidly after the exposure: three months after exposure, the lung burden was 165 μg SiO2/lung (81% reduction) and after 8 months it had decreased further to 93 μg SiO2/lung, which represents a 90% reduction. The burden of crystalline silica remained relatively unchanged post exposure being 658 and 743 μg SiO2/lung after 12 and 32 weeks, respectively. The authors explained the rapid clearance of amorphous silica by its better solubility. Silica levels of control rats varied between 28-59 μg SiO2/lung.
Applicant's summary and conclusion
- Conclusions:
- Interpretation of results (migrated information): other: no significant lung accumulation
Amorphous silica caused a steep increase in silica levels during the first 6.5 weeks, but after this time point the increment was significantly lower suggesting that the equilibrium between retention and elimination was reached. When compared to crystalline silica the clearance rate of amorphous silica was relatively rapid. - Executive summary:
In a subchronic inhalation study of Johnston et al. (2000), rats were exposed 6h/d, 5 d/wk to 50 mg SiO2/m3of hydrophilic pyrogenic silica (Aerosil® 200, MMAD 0.81 µm) or cristobalite (MMAD 1.3 μm) 3 mg/m3 for up to 13 weeks. The lung burden was measured after 6.5 and 13 weeks of exposure and after 3 and 8 months of recovery. Lung burden after 6.5 and 13 weeks exposure was 759 and 883 μg SiO2/lung for amorphous silica, respectively, and 336 and 819 μg SiO2/lung for crystalline silica. The lower increasement between 6.5 and 13 weeks of exposure suggests a phase in which retention and elimination are in equilibrium. Lung burden of amorphous silica reduced rapidly after the exposure: three months after exposure, the lung burden was 165 μg SiO2/lung (81% reduction) and after 8 months it had decreased further to 93 μg SiO2/lung, which represents a 90% reduction. The burden of crystalline silica burden remained relatively unchanged post exposure being 658 and 743 μg SiO2/lung after 12 and 32 weeks, respectively. The authors explained the rapid clearance of amorphous silica by its better solubility
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