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EC number: 200-839-4 | CAS number: 75-10-5
- 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
Acute inhalation toxicity of difluoromethane is very low with no mortality or other significant effects in rats after 4 hours exposure up to 520000 ppm (1107000 mg/m3).
Key value for chemical safety assessment
Acute toxicity: via oral route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Acute toxicity: via inhalation route
Link to relevant study records
- Endpoint:
- acute toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP compliant, near guideline study, available as unpublished report, no restrictions, fully adequate for assessment (SIDS score: 1).
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 403 (Acute Inhalation Toxicity)
- GLP compliance:
- yes
- Test type:
- standard acute method
- Limit test:
- no
- Species:
- rat
- Strain:
- other: Wistar-derived
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Harlan Olac Limited, Blackthorn, Bicester, Oxon, UK.
- Age at study initiation: young adults
- Weight at study initiation: 264-313 g (males) and 206-251 g (females)
- Housing: 5 per cage (sexes separately)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: not specified
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15-24
- Humidity (%): 50+/-15
- Air changes (per hr): 20-30
- Photoperiod (hrs dark / hrs light): 12/12 - Route of administration:
- inhalation: gas
- Type of inhalation exposure:
- nose only
- Vehicle:
- other: unchanged (no vehicle)
- Details on inhalation exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure generation: The test atmosphere was generated by passing HFC 32 from the stoch cylinder through a copper coil (4 mm id, length approximately 3-4 m) immersed in a water bath maintained at 40°C. The resulting gas was metered at a flow rate of 2.5 l/min into a monitored airstream (mixture of nitrogen and oxygen at a combined flow rate of 2.5 l/min) and into the bottom level of a PERSPEX Serial Dilution Exposure Chamber. At successively higher levels in the chamber, the atmosphere was further diluted by the addition of clean, dry air (dried and filtered using equipment supplied by Atlas-Copco, Sweden) and the removal of atmosphere via a vacuum line. Air flow rates were measured using variable area flowmeters, recorded at frequent intervals and were altered as necessary to maintain the target concentrations.
- Exposure chamber volume: length 37 cm, width 33 cm, height 20 cm
- Method of holding animals in test chamber: restraining tubes supplied by Battelle
- Method of conditioning air: mixture of nitrogen and oxygen, at successively higher levels further diluted by addition of clean, dry air
- Temperature, humidity in air chamber: 20.5-21.4°C, 39-55%
TEST ATMOSPHERE
- Brief description of analytical method used: By sampling the test atmosphere using a gas tight syringe. The samples were injected on to a gas chromatograph equipped with a flame ionisation detector.
- Nominal/analytical concentrations (NC/AC): The nominal atmospheric concentration is a concentration based on the known flow rates of test material and dilution air during the exposure period. This represents the maximum concentration to which the animals could be exposed assuming no losses within the generation or exposure systems. The nominal concentration of the test material during the exposure generation period was calculated from the following formula: NC = (FR1 / FR1 + FR2) x NC1 where FR1 and FR2 are the flow rates (l/min) of atmosphere from previous level and of dilution air respectively, NC1 is the nominal concentration of previous level.
For the highest exposure level (first stage in the dilution chamber), the nominal concentration of the previous level is 10E6ppm (ie the neat test material). To maintain an oxygen content of 20-21%, an "artificial" atmosphere was generated using a mixture of oxygen and nitrogen added to the stream of HFC32. - Analytical verification of test atmosphere concentrations:
- yes
- Remarks:
- Concentrations monitoring: every 20 minutes samples were taken during each exposure and were analysed by gas chromatography (Chromatograph: Pye Unicam Series 204, Column: Porapak PS. (80/100 Mesh) 1.5 m x 2 mm I.D., flame ionisation detector)
- Duration of exposure:
- 4 h
- Concentrations:
- Nominal and analytical concentrations are as follows (NC/AC): 17280/7510 ± 4700, 10800/85900 ± 29400 and 500000/520000 ±19200 ppm.
- No. of animals per sex per dose:
- 5
- Control animals:
- yes
- Details on study design:
- Duration of observation: 14 days
- Clinical signs: examined once daily
- Mortality: recorded once daily
- Body weight: measured on days 1, 2, 3, 8 and 15.
- Necropsy:
macroscopic examination of the main organs with particular attention to abdominal and thoracic viscera.
lungs (with trachea and larynx attached) were weighed.
microscopic examination: lungs (with bronchi) and any abnormal tissue were fixed with 10% neutral buffered formaldehyde for possible examination. - Statistics:
- two-sided Student's t-test
- Key result
- Sex:
- male/female
- Dose descriptor:
- LC0
- Effect level:
- > 520 000 ppm
- Based on:
- test mat.
- Exp. duration:
- 4 h
- Mortality:
- No deaths occurred during the study.
- Clinical signs:
- other: - During exposure: Treatment-related findings seen during exposure were confined to animals exposed to 85900 or 520000 ppm HFC 32 and these included auditory hypoaesthesia (in both groups) and increased breathing depth and reduced breathing rate in anima
- Body weight:
- There were no toxicologically significant effects on bodyweights of treated animals when compared to controls.
- Gross pathology:
- There were neither significant effects on absolute or relative lung weights nor gross findings at necropsy which were considered to be related to treatment.
- Interpretation of results:
- practically nontoxic
- Remarks:
- Migrated information
- Conclusions:
- Nose-only exposure for 4 hours to analysed atmospheric concentrations of 7510, 85900 or 520000 ppm v/v HFC 32 resulted in no mortalities and no severe toxicity. It is concluded that the median lethal concentration of HFC 32 in the rat exceeds 520000 ppm.
- Executive summary:
In an OECD guideline study (Parr-Dobrzanski RJ et al., 1992), 10 Wistar rats (5 males and 5 females) were exposed until 520,000 ppm (1,107,000 mg/m3) of difluoromethane (HFC-32) in atmosphere for 4 hours. The acute inhalation toxicity of difluoromethane was very low with no mortality. Minor clinical signs were observed in the animals exposed to the two highest concentrations (85900 ppm (183,000 g/m3) and 520000 ppm (1,107,000 g/m3) during and after exposure: reduced breathing rate, reduced activity, salivation, tail erections. Affected animals showed a rapid reversal of effects after the end of exposure.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LC50
- Value:
- 1 107 000 mg/m³ air
- Quality of whole database:
- Good with a reliable study.
Acute toxicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
In accordance with section 2 of REACH Annex XI, an acute oral and an acute dermal toxicity study do not need to be conducted as the substance is a gas.
The acute inhalation toxicity of difluoromethane is very low with no mortality in rats after 4 hours exposure to atmospheric concentrations of 7510, 85900 or 520000 ppm. Minor clinical signs were observed in the animals exposed to the two highest concentrations (85900 ppm (183000 mg/m3) and 520000 ppm (1107000 mg/m3)) during and after exposure: reduced breathing rate, reduced activity, salivation, tail erections. Affected animals showed a rapid reversal of effects after the end of exposure.
Justification for classification or non-classification
No mortality or other major significant effects occurred after exposure to 520000 ppm (1107000 mg/m3) difluoromethane for 4 hours. Therefore, the substance does not need to be classified for acute toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.
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