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EC number: 273-761-1 | CAS number: 69012-64-2 Amorphous silicon dioxide particles from the volatilization and vaporization of furnace feed materials in the manufacture of ferrosilicon and silicon.
- 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
Repeated dose toxicity: inhalation
Administrative data
- Endpoint:
- chronic toxicity: inhalation
- Type of information:
- migrated information: read-across based on grouping of substances (category approach)
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: read-across to synthetic amorphous silica
Data source
Reference
- Reference Type:
- other: proceedings
- Title:
- Chronic effects of inhaled amorphous silicas in animals.
- Author:
- Groth, D. H., Moorman, W. J., et al.
- Year:
- 1 981
- Bibliographic source:
- Proc. of Symposium on Health Effects of Synthetic Silica Particulates, Marbella, Spain. ASTM STP 732, Dunnom, D.D (Ed), American Society for Testing and Materials, 1981, pp. 118-143.
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 452 (Chronic Toxicity Studies)
- GLP compliance:
- not specified
Test material
- Reference substance name:
- Automatically generated during migration to IUCLID 6, no data available
- IUPAC Name:
- Automatically generated during migration to IUCLID 6, no data available
- Details on test material:
- - Name of test material (as cited in study report): silica gel, precipitated silica, fume silica
- Molecular formula (if other than submission substance):
- Molecular weight (if other than submission substance):
- Smiles notation (if other than submission substance):
- InChl (if other than submission substance):
- Structural formula attached as image file (if other than submission substance): see Fig.
- Substance type:
- Physical state:
- Analytical purity:
- Impurities (identity and concentrations):
- Composition of test material, percentage of components:
- Isomers composition:
- Purity test date:
- Lot/batch No.:
- Expiration date of the lot/batch:
- Radiochemical purity (if radiolabelling):
- Specific activity (if radiolabelling):
- Locations of the label (if radiolabelling):
- Expiration date of radiochemical substance (if radiolabelling):
- Stability under test conditions:
- Storage condition of test material:
- Other:
Constituent 1
Test animals
- Species:
- other: rat, guinea pig and monkey
- Strain:
- other: Sprague-Dawley rats, Hartley guinea pigs, and Cynomolgus monkeys
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Laboratory Supply Company, Inc., Indianapolis, Ind. (rats), Sweetwater Farms, Hillsboro, Ohio (guine pigs), Primate Imports Corp., Long Island, N.Y. (monkeys)
- Age at study initiation: adult monkeys
- Weight at study initiation: 300-380 g (rats), 400-800 g (guinea pigs), 2300-5400 g (monkeys)
- Fasting period before study:
- Housing: all three species individually housed during the exposures, rats and guine pigs two to four animals per cage at all other times
- Diet (e.g. ad libitum): standard laboratory pellet diets (Rodent Laboratory Chow, Guinea Pig Chow, and Monkey Chow-Jumbo from Ralston Purina, St. Louis, Mo.); monkeys were given fresh fruit (oranges, bananas, or apples) twice a week
- Water (e.g. ad libitum): tap water ad libidum
- Acclimation period: rats and guinea pis were quarantined for two weeks, monkeys for one month
ENVIRONMENTAL CONDITIONS
- Temperature (°C):
- Humidity (%):
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):
Administration / exposure
- Route of administration:
- inhalation: dust
- Type of inhalation exposure:
- whole body
- Remarks on MMAD:
- MMAD / GSD: Amount of particles <4.7 μm: 65% (pyrogenic silica), 62% (silica gel), 46% (precipitated silica)
- Details on inhalation exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel inhalation chamber 60 in. long by 57 in. wide by 57 in. high (160ft3)
- Method of holding animals in test chamber: stainless and galvanized steel open wire-mesh cages were used as exposure cageing to provide adequate distribution of the dust aerosols within the exposure chambers
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols: Silica gel and precipitated silica dust aerosols were generated by Wright dust feed mechanisms, which were affixed to each exposure chamber. Fume silica was generated with a modified fluidized bed.
- Temperature, humidity, pressure in air chamber:
- Air flow rate: dynamic flow conditions with tangential airfeed manifolds maintained at 40 L/min with a pressure pf -0.254 cm H2O
- Air change rate:
- Method of particle size determination:
- Treatment of exhaust air:
TEST ATMOSPHERE
- Brief description of analytical method used:
- Samples taken from breathing zone: yes/no
VEHICLE (if applicable)
- Justification for use and choice of vehicle:
- Composition of vehicle:
- Type and concentration of dispersant aid (if powder):
- Concentration of test material in vehicle:
- Lot/batch no. of vehicle (if required):
- Purity of vehicle: - Duration of treatment / exposure:
- up to 18 months
- Frequency of treatment:
- 5.5-6 hours/day, 5 days/week
Doses / concentrations
- Remarks:
- Doses / Concentrations:
15 mg/m3
Basis:
- No. of animals per sex per dose:
- 80 rats/dose, 20 guinea pigs/dose, 10 monkeys/dose
- Control animals:
- yes
Examinations
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes / No / No data
- Time schedule:
- Cage side observations checked in table [No.?] were included.
DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:
BODY WEIGHT: Yes / No / No data
- Time schedule for examinations:
FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes / No / No data
FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data
WATER CONSUMPTION: Yes / No / No data
- Time schedule for examinations:
OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: Yes
- Time schedule for collection of blood:
- Anaesthetic used for blood collection: Yes (identity) / No / No data
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked in table [No.?] were examined.
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked in table [No.?] were examined.
URINALYSIS: Yes / No / No data
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes / No / No data
- Animals fasted: Yes / No / No data
- Parameters checked in table [No.?] were examined.
NEUROBEHAVIOURAL EXAMINATION: No
OTHER: Pulmonary function in monkeys was tested prior the study. - Sacrifice and pathology:
- Autopsies on rats were performed after 3, 6 and 12 months of exposure, and on guinea pigs and monkeys after 10 to 18 months of exposure.
- Statistics:
- Multivariate one-way analyses of covariance between the control and each exposed group were calculated. The dependent variables (pulmonary functions) were placed into two groups for this analysis. The ventilatory mechanisms group included resistance at low frequency (RLLF), compliance at low frequency (CLLF), forced expiratory flow at 25 percent vital capacity (FEF25), forced expiratory flow at 10 percent vital capacity (FEF10%), closing volume (CV), nitrogen washout (N2), and volume of isoflow (VISFL). The lung volume group included forced vital capacity (FVC), inspiratory capacity (IC), residual volume (RV), and total lung capacity (TLC). If the multivariate analysis indicated a significant difference, then each response variable was analyzed individually by adjusted univariate analysis.
Results and discussion
Results of examinations
- Body weight and weight changes:
- not examined
- Food consumption and compound intake (if feeding study):
- not examined
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- not examined
- Haematological findings:
- no effects observed
- Clinical biochemistry findings:
- no effects observed
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- effects observed, treatment-related
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Details on results:
- CLINICAL SIGNS AND MORTALITY
BODY WEIGHT AND WEIGHT GAIN
HAEMATOLOGY
No statistically significant changes.
CLINICAL CHEMISTRY
No statistically significant changes in rats and guinea pigs. Alkaline phosphatase levels in fume silica monkeys were elevated compared to controls (however, elevation did not correlate with pathology and was probably not the result of exposure).
ORGAN WEIGHTS
GROSS PATHOLOGY
HISTOPATHOLOGY: NON-NEOPLASTIC
The most significant finding was the deposition of large quantities of amorphous silica in macrophages in the lungs and tracheal lymph nodes of exposed monkeys. Regardless of the type of amorphous silica to which they were exposed, the lungs of each monkey contained large numbers of macrophage and mononuclear cell aggregates. The size of cell aggregates varied from 40 to 600 μm in diameter and they were found in the walls of respiratory bronchioles, alveolar ducts, around venules and arterioles, and occasionally in alveolar walls distant from the aforementioned structures. More and larger aggregates appeared in the lungs exposed to precipitated silica, slightly fewer and smaller ones in the lungs exposed to fumed silica, and considerably fewer and smaller ones in the lungs exposed to silica gel. Relatively few or no macrophages containing particles of amorphous silica were found in the lungs and lymph nodes of the guinea pigs and rats. Fumed silica induced early nodular fibrosis in the lungs of the monkeys, 5– 50% of the aggregates contained collagen in varying amounts in six of the nine monkeys exposed to fumed silica. In three of the monkeys, little or no collagen was present in the aggregates.
HISTOPATHOLOGY: NEOPLASTIC (if applicable)
HISTORICAL CONTROL DATA (if applicable)
OTHER FINDINGS
Lung-function studies indicated statistically significant differences in lung volume and ventilatory mechanics between the monkeys exposed to fumed silica and the control group. In addition, monkeys exposed to precipitated silica demonstrated significantly lower lung volumes compared with controls, while monkeys exposed to silica gel had significant changes in ventilatory performance and mechanical properties.
Effect levels
- Dose descriptor:
- LOAEL
- Effect level:
- 15 mg/m³ air
- Sex:
- male
- Basis for effect level:
- other: rat, monkey; for respirable particles (<4.7 μm) about 6 to 9 mg/m³
Target system / organ toxicity
- Critical effects observed:
- not specified
Applicant's summary and conclusion
- Executive summary:
In a chronic inhalation study of Groth et al. (1981), rats, guinea pigs, and monkeys were exposed by inhalation for up to 18 months to fume, gel and precipitated synthetic amorphous silica. The concentration used was 15 mg/m3and the exposure was performed 5.5 to 6 h/day, 5 days/week. Exposure with monkeys showed the most significant findings: deposition of amorphous silica in macrophages in the lungs and tracheal lymph nodes, induction of early nodular fibrosis in the lungs, and differences in lung volume and ventilatory mechanics measurements between exposed and controls. LOAEL for amorphous silica was 15 mg/m3(total dust).
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