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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: This study is classified as reliable with restrictions because there are no statements indicating if the study was conducted according to GLPs or other accepted guidelines, and the endpoint measured was not mortality.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1994
Report Date:
1994

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The effect of acute inhalation exposure to the test substance on neurobehaviour, specifically the shortening of the duration of maximal tonic extension in male rats and the slowing of the development of tonic extension in female mice, was examined. Rats or mice were exposed to the test substance, then exposed to an electrical impulse. The effect of the exposure on the reaction to the impulse was measured.
GLP compliance:
not specified
Test type:
other: acute inhalation neurotropic effects
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): n-pentane
- Substance type: C5 aliphatic
- Physical state: Vapour
- Analytical purity: 100%

Test animals

Species:
other: rat (males) and mouse (females)
Strain:
other: Wistar albino and H
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source:
- Age at study initiation: Males: 0.5 to 1 year; Females: 2 to 4 months
- Weight at study initiation: Males: mean of 350 g; Females: not reported
- Housing: Males: 4 per cage; Females: 16 per cage
- Diet (e.g. ad libitum): Males: 12 grams per day; Females: ad libitum
- Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Climatized
- Photoperiod (hrs dark / hrs light): 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: glass chamber, diffusion tubes used for stabilization of air concentration
- Exposure chamber volume: 80 litre
- Method of holding animals in test chamber: animals placed in small plastic boxes
- Temperature, humidity, pressure in air chamber: dynamic conditions

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography
- Samples taken from breathing zone: yes
Analytical verification of test atmosphere concentrations:
yes
Remarks:
gas chromatography
Duration of exposure:
h
Remarks on duration:
4 hours for male rats and 2 hours for female mice
Concentrations:
3 concentrations, not reported
No. of animals per sex per dose:
Males: 4; Females: 8 (see details below)
Control animals:
yes
Details on study design:
- Duration of observation period following administration: animals were used for multiple experiments, and were observed accordingly
- Frequency of observations and weighing: not reported
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, body weight
Statistics:
All data were analyzed using linear regression analysis.

Results and discussion

Effect levelsopen allclose all
Sex:
male
Dose descriptor:
other: Isoeffective air concentration
Effect level:
21 000 ppm
Exp. duration:
4 h
Remarks on result:
other: 90% CL: 3200 ppm; calculated as the concentration resulting in in 37% depression of the critical effect level (i.e., shortening of the tonic extension of hindlimbs by 3 seconds)
Sex:
female
Dose descriptor:
other: Isoeffective air concentration
Effect level:
23 500 ppm
Exp. duration:
2 h
Remarks on result:
other: 90% CL: 6800 ppm; calculated as the concentration resulting in in 30% depression of the critical effect level (i.e., lengthening of the latency of extension by 0.6 seconds)
Mortality:
No mortality reported
Clinical signs:
Not reported
Body weight:
Not reported
Gross pathology:
Not reported
Other findings:
None reported

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Not classified because LC50 is greater than the requirements for a Category 4 vapour toxicant (20 mg/L) Criteria used for interpretation of results: EU
Conclusions:
No mortality was seen at exposures > 20,000 ppm for either rats or mice, so the test substance is not classified under the EU classification scheme.
Executive summary:

In an acute inhalation toxicity study, groups of young adult male Wistar strain albino rats (4 per dose level) and female H strain mice (8 per dose level) were exposed by inhalation route to n-pentane for 4 hours (males) or 2 hours (females) to whole body at 3 concentrations. 

 

Animals were examined for neurotropic effects, specifically depression of seizure responses after exposure to an electrical impulse. Mortality was not reported, and no long-term systemic effects were reported. No NOAEL was reported, and the LC50 was not calculated. The concentration resulting in 37% depression of the shortening of the tonic extension of hindlimbs by 3 seconds in male rats was found to be 21000 ppm, while the concentration resulting in 30% depression of the lengthening of the latency of extension by 0.6 seconds in mice was found to be 23500 ppm.

 

This study received a Klimisch score of 2 and is classified as reliable with restrictions because there are no statements indicating if the study was conducted according to GLPs or other accepted guidelines, and the endpoint measured was not mortality.