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EC number: 935-756-9 | CAS number: 1344-95-2
- 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
Endpoint summary
Administrative data
Link to relevant study record(s)
- Endpoint:
- basic toxicokinetics in vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1993
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- test procedure in accordance with generally accepted scientific standards and described in sufficient detail
- Remarks:
- performed under GLP
- Objective of study:
- other: elimination kinetics
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- Wistar rats were exposed to the test substance via intratracheal instillation into the lungs. The distribution of the test substance in the lung was analysed by scanning electron microscopy after 2 and 14 days, 1, 3, and 6 months to determine elimination kinetics.
- GLP compliance:
- yes (incl. QA statement)
- Radiolabelling:
- no
- Species:
- rat
- Strain:
- Wistar
- Sex:
- female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Wiga, Sulzfeld, FRG
- Age at study initiation: about 10 weeks
- Weight at study initiation: about 200 g
- Housing: Individually in polycarbonate (MakrolonTM) type III cages
- Diet: Commercail chow in pellet form (Altromin 1324 N), fresh diet offered every week
- Water: Fresh, filtered tap water, offered fresh weekly or more often if necessary
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
No data
IN-LIFE DATES:
No data - Route of administration:
- intratracheal
- Vehicle:
- other: 0.9% NaCl solution
- Details on exposure:
- TYPE OF INHALATION EXPOSURE: other: intratracheal instillation
TEST ATMOSPHERE:
Two fractions of the stock test materials were prepared using a dry sizing technique:
1) thoraric particulate mass, median aerodynamic diameter of 10 µm±1.0 µm, with a geometric standard deviation of 1.5 (±0.1)
2) respirable particulate mass, median aerodynamic diameter of 3.5 µm±0.3 µm, with a geometric standard deviation of 1.5 (±0.1) - Duration and frequency of treatment / exposure:
- Single exposure
- Dose / conc.:
- 2 other: mg fibres in 0.3 mL of 0.9% NaCl solution
- No. of animals per sex per dose / concentration:
- 30 animals/fraction or negative control
10 animals/positive control - Control animals:
- yes
- Positive control reference chemical:
- UICC crocidolite (substance with demonstrated high biopersistence)
- Details on study design:
- - Rationale for animal assignment (if not random): animals were allocated on a body weight bases to assure all animals had body weights within the mean weight ±20%
- Details on dosing and sampling:
- The following parameters were investigated:
- Distribution in the lungs, with Scanned Electron Microscopy (SEM)
- Body weight
- Lung weight
- Clinical signs
- Histopathology of the lung - Statistics:
- Dunnets procedure - body weight and lung weight multiple comparison of means
Comparison of regression coefficients (Sachs, 1992) - clearance kinetics of different test materials
Fishers exact test - homogeneity of contingency tables for histopathological data - Preliminary studies:
- Not relevant
- Details on absorption:
- Not relevant
- Details on distribution in tissues:
- Not relevant
- Details on excretion:
- Not relevant
- Details on metabolites:
- Not relevant
- Conclusions:
- Interpretation of results (migrated information): other: crystalline calcium silicate hydrate is eliminated from the lung very fast
Under the conditions of the study, elimination of crystalline calcium silicate hydrate from the lungs after intratracheal instillation was very fast. No half time could be calculated as 2 days after exposure, minimal presence of crystalline calcium silicate hydrate was observed in the lung. - Executive summary:
Wistar rats were exposed to xonotlite via intratracheal instillation into the lungs. The distribution of the test substance in the lung was analysed by scanning electron microscopy after 2 and 14 days, 1, 3, and 6 months to determine elimination kinetics.
A fraction of 0.5% of xonotlite crystals was found to be longer than 5 µm. No effects were observed on survival, body weight and wet lung weights. Furthermore, the histopathological examination of the lungs did not reveal changes which could be related to the test material.
The elimination kinetics of xonotlite from the lung was very fast, 2 days after intratracheal installation, minimal presence of xonotlite fibers or aggregations of such fibers in the lung was observed. Therefore, no half-time could be calculated (half-time<2). The fast elimination may be due to fast dissolution of xonotlite crystals as a result of the small diameter and large surface. The absence of lesions in the lung may also be explained by dissolution of xonotlite.
Reference
A fraction of 0.5% of xonotlite crystals was found to be longer than 5 µm. No effects were observed on survival, body weight and wet lung weights. Furthermore, the histopathological examination of the lungs did not reveal changes which could be related to the test material.
2 days after intratracheal instillation, SEM analysis showed minimal presence of xonotlite fibres or aggregations of such fibres in the lung. The estimated mass of single fibers was <10 µg per lung, in the thoraric fraction 0.4% of the mass fraction of single fibers present in the injected test material was detectable in the lungs, whereas only 0.08% of the alveolar fraction was detected. Furthermore, about 85 -89% of the agglomerates were eliminated. After 3 months, no fibers or agglomerates were detected. Based on the very rapid 2 -day clearance, it was not possible to calculate a half-time (half-time < 2 days).
Description of key information
- Molecular weight – xonotlite: 741.99g/mol, tobermorite 702.36 g/mol
- Water solubility – decomposes in water: 37 mg/L based on silicium analysis
-
Particle size distribution – D (0.5) is between 35.7 um and 61.3 um.
No particles were found under 0.417 µm and above 316.228 µm
- Log Kow – not applicable (inorganic)
- Vapour pressure – not applicable (inorganic)
Background
A key study is available in which the elimination of xonotlite/tobermorite from the lung was tested. Also the physicochemical properties are available to assess the toxicokinetics behaviour.
Physical and chemical properties
The physical/chemical properties that are of importance to assess the toxicokinetics behaviour of xonotlite/tobermorite are:
Absorption
The calcium silicate hydrate is xonotlite/tobermorite, which are inorganic substances. Therefore a log Kow and vapour pressure is not applicable. The water solubility is moderate; the crystalline structure decomposes in water and the elements are present as ions in solution. Based on the water solubility study, a hydrolysis rate of <6 days was estimated.
Exposure through inhalation of xonotlite/tobermorite particles is the main route of possible exposure. The elimination kinetics (biodurability) of xonotlite/tobermorite was investigated by Bellman (1994), in a study in which the substance was administered by intratracheal instillation in rats. Elimination from the lungs was studied by scanning electron microscopy after 2 and 14 days, 1, 3, and 6 months.
No effects were observed on survival, body weight and wet lung weights. Furthermore, the histopathological examination of the lungs did not reveal changes which could be related to the test material. The elimination kinetics of xonotlite from the lung was very fast, 2 days after intratracheal installation, minimal presence of xonotlite fibers or aggregations of such fibers in the lung was observed. Therefore, no half-time could be calculated (half-time<2 days). The fast elimination may be due to fast dissolution of xonotlite crystals as a result of the small diameter and large surface, and the absence of lesions in the lung by dissolution of xonotlite fibers. (Bellman, 1994)
Based on the molecular weight and the water solubility, absorption via the oral and dermal route is expected to be limited. This is supported by the absence of effects observed in the skin irritation and skin sensitization study.
Conclusion
Xonotlite/tobermorite can be absorbed after respiratory exposure, but the amount of absorption will be limited, due to the fast clearance of particles from the lungs, for which the half-time is <2 days. Based on the physical/chemical properties, oral absorption and dermal absorption are expected to be limited.
Key value for chemical safety assessment
Additional information
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