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Acute Toxicity: inhalation

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Administrative data

acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, non-guideline study, some restrictions in reporting, acceptable for assessment

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
Test type:
standard acute method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
tert-butyl methyl ether
EC Number:
EC Name:
tert-butyl methyl ether
Cas Number:
Molecular formula:
tert-butyl methyl ether
Details on test material:
MTBE, X-801-25, 100%

Test animals

other: Charles River albino
Details on test animals or test system and environmental conditions:
The animals had a average body weight of 240 grams.
The animals were housed individually.
The animals were permitted a standard laboratory diet plus water ad libitum.

- Temperature (°C): 23-25
- Test atmosphere pressure (inches Hg): 29.90-30.24

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
not specified
Details on inhalation exposure:
Exposure was in a Plexiglas inhalation chamber of 70 liters. The chamber was designed so that the animals could be introduced to the test atmosphere after 99 percent of the desired vapour concentration was established.
Vapour was generated by bubbling a stream of clean dry air through the undiluted test material. The resulting air-vapour stream was then introduced into the exposure chamber at the top center, dispersed by a baffle plate and exhausted at the bottom of the chamber.
Average nominal vapour generation were calculated by dividing the total weight of test material vaporized by the total volume of air used during each inhalation exposure.
Analytical verification of test atmosphere concentrations:
not specified
Duration of exposure:
4 h
44, 65, 86, 99, 167 and 395 mg/l
No. of animals per sex per dose:
Control animals:
not specified
Details on study design:
Each experiment was designed to run for a four-hour period during which time observations were made with respect to incidence of mortality and reactions displayed. At the end of the exposure period, the rats were returned to their stock cages and observed for the following 14 days.
A body weight was determined for each animal at the end of the 14-day observation period. Gross pathologic examinations were scheduled to be conducted upon all animals which might succumb during the test period as well as those sacrificed at the end of the 14 day observation period.
The LC50 was calculated using the techniques of Litchfield and Wilcoxon.
For analysis of the effects, no details were reported.

Results and discussion

Effect levels
Dose descriptor:
Effect level:
85 mg/L air
95% CL:
> 79 - < 91
Exp. duration:
4 h
In the 86 mg/l group, six animals died and in the higher dose groups, all animals died. In the 86 mg/l concentration group, the time of death varied from 110 to 225 minutes after the start of exposure, in the 99 mg/l concentration group, the time of death varied from 96-240 minutes, in the 167 mg/l concentration group, the time of death varied from 59-80 minutes and in the high dose group, the time was 25-51 minutes.
Clinical signs:
other: The clinical signs included ataxia, tremors, lacrimation, clonia, unconsciousness and hyperactivity. Surviving animals appeared normal the morning after exposure.
Body weight:
No adverse effects were observed.
Gross pathology:
Necropsy of the animals which died revealed slight to moderate hyperemia in the lungs. The animals that survived the 14-day observation period had minimal to mild lung hyperemia.

Applicant's summary and conclusion