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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non GLP, non-guideline, animal experimental study. Limitations in design and reporting but otherwise adequate for assessment.

Data source

Reference
Reference Type:
publication
Title:
Isobutane
Author:
Aviado DM, Zakheri S and Watanabe T
Year:
1977
Bibliographic source:
Non-Fluorinated Propellants and Solvents for Aerosols, chapter 6 pp 61-72. CRC Press, Cleveland, Ohio

Materials and methods

Test guideline
Qualifier:
no guideline available
Deviations:
not applicable
Remarks:
Pre-guideline study
Principles of method if other than guideline:
Groups of male mice were exposed to isobutane at various concentrations in air for 2 hours. Oxygen was added to prevent death from hypoxia.
GLP compliance:
no
Test type:
other: LC50

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Isobutane
- Substance type: A hydrocarbon
- Physical state: gas
- Composition of test material,

Test animals

Species:
mouse
Strain:
CF-1
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Wilmington, Massachusetts
- Weight: 20 to 25g

ENVIRONMENTAL CONDITIONS
- no data

IN-LIFE DATES
- no data

Administration / exposure

Route of administration:
inhalation: gas
Type of inhalation exposure:
whole body
Vehicle:
other: no data
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Glass chamber
- Exposure chamber volume: 10L
- Source and rate of air:The gaseous mixture was flushed into the chamber at a rate of 3L/min

Oxygen was added (25% of the volume of isobutane) to prevent death due to hypoxia
Analytical verification of test atmosphere concentrations:
not specified
Duration of exposure:
120 min
Concentrations:
36, 40, 50, 55, 55, 60 and 65 % v/v
No. of animals per sex per dose:
10 males
Control animals:
no
Details on study design:
- Duration of observation period following administration: none
Statistics:
An LC50 and 95% confidence limits were calculated by a probit method

Results and discussion

Effect levelsopen allclose all
Sex:
male
Dose descriptor:
LC50
Effect level:
52.04 other: %
95% CL:
48.78 - 55.3
Exp. duration:
120 min
Remarks on result:
other: Regression coefficient 0.9662
Sex:
male
Dose descriptor:
LC50
Effect level:
520 400 ppm
Exp. duration:
120 min
Sex:
male
Dose descriptor:
LC50
Effect level:
1 237 mg/L air
Exp. duration:
120 min
Mortality:
Mortality was 0, 10, 30, 50, 90 and 100% at concentrations of 36, 40, 50, 55, 55, 60 and 65 % respectively.
Clinical signs:
Signs of central nervous system depression, rapid and shallow respiration, loss of posture and apnea were observed.
Body weight:
Not reported

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: other: EU (DSD)
Conclusions:
The 2-hour LC50 of isobutane was determined to be 52.04% v/v (approximately 520,400 ppm or 1237 mg/L).
Executive summary:

The authors examined lethality in male mice exposed for 2 hours to isobutane in air.

The LC50was 52.04 +3.26 % v/v (approximately 520,400 ppm or 1237 mg/L) (MW 58.12)