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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
Developmental toxicity / teratogenicity
Administrative data
- Endpoint:
- developmental toxicity
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment (SIDS score: 1b).
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 1 994
- Report date:
- 1994
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 414 (Prenatal Developmental Toxicity Study)
- GLP compliance:
- yes
- Limit test:
- no
Test material
- Reference substance name:
- Difluoromethane
- EC Number:
- 200-839-4
- EC Name:
- Difluoromethane
- Cas Number:
- 75-10-5
- Molecular formula:
- CH2F2
- IUPAC Name:
- difluoromethane
- Details on test material:
- Name of test material: difluoromethane
Source: ICI Chemicals and Polymers
Batch number: A108 and A110
Purity: 99.9% v/v
Constituent 1
Test animals
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or test system and environmental conditions:
- TEST ORGANISMS:
- Source: Interfauna UK (Huntingdon, Cambridgeshire, UK)
- Age: 16-24 weeks
- Weight at study initiation: 3030-4020 g
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 3
- Humidity (%): 50 +/- 15
- Photoperiod (hrs dark / hrs light): 14 / 10
Administration / exposure
- Route of administration:
- inhalation
- Type of inhalation exposure (if applicable):
- whole body
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Atmosphere generation: The pressurised gas passed from the cylinder supplied through a manifold to 3 feedlines each one connected to an exposure chamber. The rate of gas flow to each chamber was controlled by an in-line needle valve and monitored by an in-line flow tube (Meterate Glass Precision Engineering Ltd). The gas entered the base of an aluminium and glass elutriation column where it was mixed with diluent air. Different chamber concentrations of HFC 32 were achieved by varying the rate at which the gas was introduced into the diluent air stream. The total gas/air mixture flow to each chamber was maintained at 200 l/minute.
TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography with flame ionisation detector. - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Samples of chamber air were withdrawn at approximately hourly intervals during exposure. Samples were withdrawn into gas tight syringes and injected into a gas chromatograph via a gas sample loop (Pye Unicam Series 204 chromatograph, inluding a 1m x 3mm Porapak Q 80-100 mesh column and coupled to a flame ionisation.
- Details on mating procedure:
- Females were mated with males of proven fertility; once cairns had been observed, each female was allowed to remain with the male for at least one hour. On successfully completing coitus, each doe had been injected intravenously with 25 IU of Chorulon (luteinizing hormone) to ensure that ovulation had taken place. The day of mating was considered as Day 0 of pregnancy.
- Duration of treatment / exposure:
- from gestation days 6 to 18
- Frequency of treatment:
- 6 hours/day
- Duration of test:
- 29 days post coitum
- No. of animals per sex per dose:
- 24 females/group
- Control animals:
- yes, concurrent vehicle
- Details on study design:
- The study was conducted in two phases because of the constraints of the exposure chambers in relation to the number of animals used. Both phases consisted of 48 animaIs supplied in three consecutive batches: the first batch of animals for the second phase of the study was delivered 4 days after termination of the first phase.
Statistical analyses of bodyweight and litter data showed that there were no interaction between exposure and phase allowing presentation of the combined data from the two phases.
Examinations
- Maternal examinations:
- PARAMETERS ASSESSED DURING STUDY:
- Clinical observations: at least once daily
- Maternal mortality: at least once daily
- Maternal body weight: on gestation days 0, 2, 6, 8, 10, 14, 19, 23 and 29
- Food consumption: recorded on gestation days 0, 2, 6, 8, 10, 14, 19, 23 and 29 - Ovaries and uterine content:
- On day 29 of pregnancy, the females were killed by cervical dislocation and the fetuses removed by Caesarean section. Uteri and their content were examined: number of corpora lutea; number and position of implantation sites, classified as live fetuses, early intra-uterine deaths (presence of decidual or placental tissue only) or late intra-uterine deaths (presence of embryonic/fetal tissue plus placental tissue).
Calculated parameters:
Pre-implantation loss (%) = [(number of corpora lutea - number of implantations) / number of corpora lutea] x 100 .
Post-implantation loss (%) = [(number of implantation sites - number of live fetuses) / number of implantation sites] x 100. - Fetal examinations:
- Number of live and dead fetuses, weight of individual fetuses, sex ratio, external examination, head examination, skeletal examination (modified Dawson technique).
Morphological abnormalities were classified as malformations (rare and/or probably lethal), anomalies (minor differences from "normal" but relatively frequent) or variants (differences regularly observed in the control group). - Statistics:
- Analysis of variance followed by a William's test or Kruskal-Wallis test followed by a Shirley's test.
Results and discussion
Results: maternal animals
Maternal developmental toxicity
- Details on maternal toxic effects:
- Maternal toxic effects:no effects
Details on maternal toxic effects:
CLINICAL OBSERVATIONS:
No exposure-related clinical signs were observed.
MATERNAL MORTALITY:
There were no mortalities at 15000 and 50000 ppm. At 5000 ppm there was one mortality post commencement of exposure and this was considered to be unrelated to treatment.
MATERNAL BODY WEIGHT:
At 50000 ppm, there was no obvious effect on bodyweight during the first 2 days of exposure (Days 6 to 8 of pregnancy). During Days 8 to 10, however, there was a slight but statistically significant effect on bodyweight; a group mean weight loss of 22 g was recorded for treated rabbits during this period (9/20 animals showed weight loss) compared with a mean weight gain of 28 g among controls (5/22 animals showed weight loss). From Day 10, recovery was recorded, with weight gains being generally comparable with controls. There was no obvious or statistically significant effect on bodyweight at 5000 and 15000 ppm.
FOOD CONSUMPTION:
There was no obvious effect on food intake.
Effect levels (maternal animals)
- Dose descriptor:
- NOAEL
- Effect level:
- 50 000 ppm
- Basis for effect level:
- other: maternal toxicity
Results (fetuses)
- Details on embryotoxic / teratogenic effects:
- Embryotoxic / teratogenic effects:no effects
Details on embryotoxic / teratogenic effects:
LITTER PARAMETERS:
The number of corpora lutea, implants and litter sizes from treated groups did not significantly differ from control values. Pre- and post-implantation loss values were comparable in all groups. The only statistically significant change was the mean for total embryonic deaths that was lower in the high-dose group (0.7) when compared to control (1.3) but this finding has no toxicological significance. Fetal weight was unaffected by treatment and no significant changes were observed on sex ratio.
EXAMINATION OF FOETUSES:
- Malformations: The number of malformed foetuses/litters observed in control, low, mid and high-dose groups were 4 (4), 6 (6), 2 (2) and 8 (5) respectively, the differences being not statistically significant. Although the incidence of malformed foetuses at 50000 ppm is higher than in controls, as there is no consistent pattern to the type of structural defects observed among foetuses in this group, this finding is considered likely to be coincidental. This increased incidence of malformations in the high-dose group was essentially due to 4 foetuses with microphthalmia compared to 0 in the control group, confined in only 2 litters out of 20 and from study phase 2. Since microphthalmia was not observed among phase 1 litters and overall only 2/20 litters were affected, the higher incidence in this group is considered to be coincidental and unrelated to maternaI exposure. The mean percentage incidence of malformed foetuses at 5000 and 15000 ppm was comparable with controls. No foetuses in these groups showed microphthalmia.
- Minor anomalies: There was no obvious adverse effect of exposure on the incidence of foetuses showing visceral anomalies or keletal anomalies.
- Skeletal variants: The percentage incidence of foetuses displaying variant sternebrae and 13 ribs were comparable in all groups and did not indicate any adverse effects of exposure.
Effect levels (fetuses)
open allclose all
- Dose descriptor:
- NOAEL
- Effect level:
- 50 000 ppm
- Basis for effect level:
- other: teratogenicity
- Dose descriptor:
- NOAEL
- Effect level:
- 50 000 ppm
- Basis for effect level:
- other: fetotoxicity
Fetal abnormalities
- Abnormalities:
- no effects observed
Overall developmental toxicity
- Developmental effects observed:
- no
Applicant's summary and conclusion
- Conclusions:
- At 50000 ppm, the maternal response to exposure was minimal and confined to a slight and transient loss of body weight during gestation days 8 to 10. There were no obvious adverse effects on fetuses. So the NOAEL for maternal toxicity and for foetus development were both considered to be equal or greater than 50000 ppm.
- Executive summary:
Groups 24 mated female New-zealand rabbits were exposed to 5000, 15000 and 50000 ppm HFC-32 in the day 6-18 of pregnancy for 6 hrs/day. Animals were housed individually in metal cages and exposed whole body in chambers. HFC-32 concentrations were monitored at 1 hour interval during the exposure periods.
All females were subjected to daily examination for clinical signs of toxicity. Body weight gain and food consumption were measured regularly during exposure. On day 29 of pregnancy the animals were killed and examined for pathological changes. Developmental and teratogenic potential of HFC-125 was assessed in the litter and fetuses by examination of the typical parameters as the number of corpora lutea, number and distribution of live young, number and distribution of embryofoetal deaths, individual and litter foetal weight and foetal abnormalities.
At 50000 ppm, the maternal response to exposure was minimal and confined to a slight and transient loss of body weight during gestation days 8 to 10. There were no obvious adverse effects on fetuses. So the NOAEL for maternal toxicity and for foetus development were both considered to be equal or greater than 50000 ppm.
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