1,1-difluoroethane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labelling and/or risk assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1975

Report date:

1975

Materials and methods

Principles of method if other than guideline:

Male rats were exposed to the test substance at 6.64, 17.52, 31.9, 38.3, and 45.75% for 4 hours and were observed for 14 day after treatment. Gross pathology was performed on surviving rats after 14 days.

GLP compliance:

not specified

Test type:

other: Acute Lethal Concentration (ALC) Test

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,1-difluoroethane

EC Number:

200-866-1

EC Name:

1,1-difluoroethane

Cas Number:

75-37-6

Molecular formula:

C2H4F2

IUPAC Name:

1,1-difluoroethane

Details on test material:

- Purity: >99.9%

Test animals

Species:

rat

Strain:

other: Chr-CD

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Not reported
- Weight at study initiation: 240-297 g
- Fasting period before study: No
- Housing: Not reported
- Diet (e.g. ad libitum): Not reported
- Water (e.g. ad libitum): Not reported
- Acclimation period: Not reported

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Not reported
- Humidity (%): Not reported
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): Not reported

Administration / exposure

Route of administration:

inhalation: gas

Type of inhalation exposure:

not specified

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Exposure chamber; no further details provided
- Exposure chamber volume: Not reported
- Method of holding animals in test chamber: Not reported
- Source and rate of air: Not reported
- Method of conditioning air: Not reported
- System of generating particulates/aerosols: The gas was regulated through a calibrated flowmeter into a mixing chamber. Regulated flows of air and/or oxygen were used as the carrier gas from the mixing chamber to the exposure chamber. For the exposure with an analytical concentration of 6.64% (v/v), only air was used as the carrier gas. Starting with the 17.52% exposure, the chamber oxygen concentrations were 16-17%, which can cause hypoxemic symptoms. All subsequent exposures had oxygen added in an amount sufficient to maintain a chamber oxygen concentration of ~20%.
- Treatment of exhaust air: Not reported
- Temperature, humidity, pressure in air chamber: Not reported

TEST ATMOSPHERE
- Brief description of analytical method used: Atmospheres were sampled at 30-minute intervals and analyzed by thermal conductivity gas chromatography. Concentrations were determined from a standard curve.
- Samples taken from breathing zone: yes

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Thermal conductivity gas chromatography

Duration of exposure:

4 h

Concentrations:

6.64, 17.52, 31.9, 38.3, and 43.75%. (66400, 175200, 319000, 383000, and 437500 ppm)

No. of animals per sex per dose:

6 males per concentration

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: Not reported
- Frequency of weighings: Not reported
- Necropsy of survivors performed: yes

Results and discussion

Effect levels

Sex:

male

Dose descriptor:

LC50

Effect level:

> 43.75 other: % (437500 ppm)

Exp. duration:

4 h

Remarks on result:

other: Mortality in 2/6 at 43.75% and 1/6 at 38.3%. At ≥ 17.52% lethargy, laboured breathing, reduced responsiveness to sound were observed. At 6.64% only hyperaemia and shallow breathing were observed.

Mortality:

Mortality ratio of 1/6 occurred at 38.3% (383000 ppm) and 2/6 occurred at 43.75% (437500 ppm).

Clinical signs:

other: Shallow breathing and hyperaemia were observed at 6.64%. During subsequent exposures additional signs observed included laboured breathing, lethargy, and unresponsiveness to sound were observed during exposure. Laboured breathing was more noticeable as

Gross pathology:

No gross changes were observed.

Applicant's summary and conclusion

Conclusions:

The study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).

4-hour ALC = 38.3% (v/v) with oxygen added to maintain a chamber level of ca. 20% O2.

Executive summary:

Male rats were exposed to 6.64, 17.52, 31.90, 38.3, or 43.75% (v/v) (66400, 175200, 319000, 383000 or 437500 ppm) of the test substance for 4 hours and were observed for 14 days. At the end of 14 days all surviving rats were given a gross necropsy. The 4-hour ALC (approximate lethal concentration) was 38.3% (v/v; 383000 ppm) with oxygen added to maintain a chamber level of ~20%.