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EC number: 235-231-8 | CAS number: 12136-78-6
- 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
Description of key information
In an acute oral toxicity study (OECD 401) young adult Crl:CD (SD) rats (5 animals per sex and dose) were orally exposed to the source substance Sodium molybdate in corn oil at concentrations of 3200, 5000 and 6400 mg/kg bw. Mortality occurred within the different dose groups. The oral LD50 for both sexes was considered to be 4233 mg/kg body weight. This value equals 3136 mg/kg bw of the target substance Molybdenum disilicide.
In an acute inhalation toxicity study equivalent to OECD 403, groups of young male and female Sprague-Dawley rats (5 per sex) were exposed via the inhalation route to the source substance Sodium molybdate (99.7% purity) for 4 hours to the whole body at a mean concentration of 1.93 mg/L. No mortality or distinct clinical signs were observed after exposure to Sodium molybdate. The LC50 for both sexes was considered to be greater than 1.93 mg/L.
Key value for chemical safety assessment
Acute toxicity: via oral route
Link to relevant study records
- Endpoint:
- acute toxicity: oral
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- For justification of read-across please refer to the read-across report attached to IUCLID section 13.
- Reason / purpose for cross-reference:
- read-across source
- Sex:
- male/female
- Dose descriptor:
- LD50
- Effect level:
- 4 233 mg/kg bw
- Based on:
- test mat.
- Mortality:
- After a single oral dose of Sodium molybdate at a concentration of 3200 mg/kg bw three male and one female died within 5 hours after treatment. At 5000 mg/kg bw one male died and two female animals died within 2 days after treatment. After treatment with 6400 mg/kg bw all animals died within 2 hours after treatment.
- Clinical signs:
- other: Piloerection was observed in all rats within five minutes after treatment. This sign was accompanied on Day 1 and/or later intervals by: - hunched posture, waddling and pallor of the extremities in all rats dosed at 3200 and 5000 mg/kg bw , less commonly
- Gross pathology:
- No macroscopic abnormalities were observed
- Interpretation of results:
- GHS criteria not met
- Conclusions:
- In conclusion, the oral LD50 value in rats after treatment with Sodium molybdate was 4233 mg/kg body weight.
- Executive summary:
In an acute oral toxicity study (OECD 401) young adult Crl:CD (SD) rats (5 animals per sex and dose) were orally exposed to Sodium molybdate in corn oil at concentrations of 3200, 5000 and 6400 mg/kg bw. Animals were observed for 14 days. All animals died in the high dose group. At 5000 mg/kg bw one male died and two female animals died and at 3200 mg/kg bw three male and one female died. There were treatment related clinical signs and slight changes in body weight. No treatment-related gross pathology abnormalities were observed after 14 days. Based on the mortality occured after treatment with Sodium molybdate, the oral LD50 value both in female and male Crl:CD (SD) rats was considered to be 4233 mg/kg body weight. Based on the LD50 for administered Sodium molybdate the LD50 for the target substance Molybdenum disilicide can be calculated with 3136 mg/kg bw (not accounting for differences in solubility/bioavailability).
This information is used in a read-across approach in the assessment of the target substance.
For justification of read-across please refer to the attached read-across report (see IUCLID section 13).
Reference
Preliminary study:
The results indicated that the acute median lethal oral dose (LD50) to male and female rats of Sodium molybdate was greater than 1000 mg/kg body weight.
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Dose descriptor:
- LD50
- Value:
- 3 136 mg/kg bw
- Quality of whole database:
- Guideline study
Acute toxicity: via inhalation route
Link to relevant study records
- Endpoint:
- acute toxicity: inhalation
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- For justification of read-across please refer to the read-across report attached to IUCLID section 13.
- Reason / purpose for cross-reference:
- read-across source
- Analytical verification of test atmosphere concentrations:
- yes
- Sex:
- male/female
- Dose descriptor:
- LC50
- Effect level:
- > 1.93 mg/L air
- Based on:
- test mat.
- Exp. duration:
- 4 h
- Mortality:
- There were no deaths during the study.
- Clinical signs:
- other: During exposure: Partial closing of the eyes was seen in rats exposed to Sodium molybdate. This sign is considered to be consistent with a non-specific response to exposure to high concentration of dust. During the observation period: No signs of toxicity
- Body weight:
- Small losses in body weight or a reduced rate of body weight gain were observed in rats exposed to Sodium molybdate for up to three days after exposure. Subsequently the rate of body weight gain of the exposed rats was similar to that of the control rats.
- Gross pathology:
- Macroscopic pathology:
The lungs of two control rats had dark areas on the surface of the lungs and the lungs of one male rat exposed to Sodium molybdate were congested (animal 95).
Microscopic pathology:
No changes considered to be of toxicological significance were observed in the lung sections examined. - Other findings:
- Food consumption:
Food consumption was reduced for two days following exposure to Sodium molybdate. Subsequently, food consumption for exposed rats was similar to that for control rats.
Water consumption:
Water consumption was increased on Day 3 of the observation period and also, in male rats only, on day 4 after exposure.
Lung to body weight ratio:
The lung weight for one male rat (animal 95) exposed to Sodium molybdate was higher than normal. The ratio was considered to be within normal limits for all other rats. - Interpretation of results:
- GHS criteria not met
- Conclusions:
- In conclusion, under the conditions of the test, the LC50 of Sodium molybdate is greater than 1.93 mg/L.
- Executive summary:
In an acute inhalation toxicity study equivalent to OECD 403, groups of young male and female Sprague-Dawley rats (5 per sex) were exposed via inhalation route to Sodium molybdate (99.7% purity) for 4 hours to the whole body at a mean concentration of 1.93 mg/L. Animals then were observed for 14 days. No mortality or distinct clinical signs were observed after exposure to Sodium molybdate. Since no mortality occured during the 14-day observation period, the LC50 for both sexes is greater than 1.93 mg/L.
This information is used in a read-across approach in the assessment of the target substance.
For justification of read-across please refer to the attached read-across report (see IUCLID section 13).
Reference
Table 1: Concentrations of Sodium Molybdate | |||
Sample | Time | Test Item in air (mg/L) | |
2.1 | 0h : 30 min | 2.01 | |
2.2 | 1h : 00 min | 1.85 | |
2.3 | 2h : 00 min | 1.94 | |
2.4 | 3h : 00 min | 1.93 | |
2.5 | 3h : 50 min | 1.91 | |
mean | 1.93 |
Variation: 8%
Table 2: Particle Size Distribution | |||||||
Sample | Time taken | Stage | Particle size range (µm) | Amount collected (mg) | % of total | % respirable (< 3.5 µm a.d.) | |
PSD1 | 1h : 40 min | 3 | 9.80 | 0.37 | 42.50 | 31.00% | |
4 | 6.00 | 0.09 | 10.30 | ||||
5 | 3.50 | 0.14 | 16.10 | ||||
6 | 1.55 | 0.27 | 31.00 | ||||
7 | 0.93 | 0.00 | 0.00 | ||||
8 | 0.52 | 0.00 | 0.00 | ||||
Filter | 0.00 | 0.00 | 0.00 | ||||
PSD2 | 3h : 30 min | 3 | 9.80 | 0.34 | 30.60 | 20.70% | |
4 | 6.00 | 0.31 | 27.90 | ||||
5 | 3.50 | 0.23 | 20.70 | ||||
6 | 1.55 | 0.23 | 20.70 | ||||
7 | 0.93 | 0.00 | 0.00 | ||||
8 | 0.52 | 0.00 | 0.00 | ||||
Filter | 0.00 | 0.00 | 0.00 | ||||
mass median aerodynamic diameter: 6.9 µm; standard geometric diviation: 2.71 |
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
Acute toxicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
No data is available for Molybdenum disilicide (target substance). Thus, available data from Sodium molybdate was used in a read-across approach. Due to a lower water solubility of Molybdenum disilicide compared to Sodium molybdate the resulting bioavailability (toxicity potential) would also be expected to be lower. Therefore, the read across to the source substance Sodium molybdate is adequately protective. Details on the read-across rational are provided in section 13.
In an acute oral toxicity study (OECD 401) young adult Crl:CD (SD) rats (5 animals per sex and dose) were orally exposed to Sodium molybdate in corn oil at concentrations of 3200, 5000 and 6400 mg/kg bw. Mortality occurred within the different dose groups. The acute median lethal oral dose (LD50) to male and female rats was calculated using the method of Finney (1971, Probit Analysis). The oral LD50 for both sexes was calculated to be 4233 mg/kg body weight. This value equals 3136 mg/kg bw of the target substance Molydenum disilicide.
In an acute inhalation toxicity study equivalent to OECD 403, groups of young male and female Sprague-Dawley rats (5 per sex) were exposed via the inhalation route to Sodium molybdate (99.7% purity) for 4 hours to the whole body at a mean concentration of 1.93 mg/L (higher concentrations technically not possible). No mortality or distinct clinical signs were observed after exposure to Sodium molybdate. The LC50 for both sexes was considered to be greater than 1.93 mg/L.
Justification for classification or non-classification
Based on the available data Molybdenum disilicide does not warrant classification for acute toxicity. LD50 values for the oral route are above the limit values of the relevant OECD guidelines. The LC50 value received from an acute inhalation study was greater than 1.93 mg/L (as Sodium molybdate).
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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