(1-methylpropylidene)bis[tert-butyl] peroxide

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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

See attached document.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1979

Report date:

1979

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

no

Test type:

traditional method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Di-tert-butyl sec-butylidene diperoxide

EC Number:

218-507-2

EC Name:

Di-tert-butyl sec-butylidene diperoxide

Cas Number:

2167-23-9

Molecular formula:

C12H26O4

IUPAC Name:

2,2-bis(tert-butylperoxy)butane

Test material form:

liquid

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Fifty male and fifty female SPF-reared rats (Cpb; WU, Wistar Random) were obtained from the Central Institute for the Breeding of Laboratory Animals TNO, Zeist, The Netherlands. At the beginning of the study the mean body weight of the males was 180 g and that of the females 135 g.
During the 2-week observation period foll owing the exposure the animals were kept in stainless steel cages (5 to a cage), which were suspended in an open rack in an animal room. They received ad libitum the Institute's stock diet for rats and bottled unfluoridated water. However, during exposure the animals had no access to water and food.
The temperature and the relative humidity in the animal room were 21±1°C and 50 - 60 per cent respectively; they were automatically controlled.

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

>= 1.2 - <= 3.3 µm

Details on inhalation exposure:

Exposure chamber:
A stainless steel exposure chamber, having a capacity of 1.5 m^3 was used. The rats were kept individually during the exposure in wire-screen cages to prevent crowding and minimize filtration of inspired air by the animals' fur. They could be continuously observed through the hard glass entrance door of the chamber.

Aerosol generator
Trigonox D-B 50 was dispersed to a fine mist by means of a stainless steel/glass aerodynamic nozzle nebulizer. The nebulizer was provided with a baffle in order to remove the larger droplets from the mist produced. The mist was passed through the exposure chamber with a total airflow of 1.6 m^3/h for Trigonox D-B 50.

Analysis:
Analysis of the test atmosphere of Trigonox D-B 50 was performed gravimetrically. Samples of the atmosphere was taken by passing a measured quantity of the test atmosphere through a Cambridge glassfibre filter at intervals of about 1.5 hour. Particle size determinations and counts were carried out in samples taken from the atmosphere in the chamber with a Cascade Impactor.

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Concentrations:

2.42 mg/L

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

After the exposure period the animals were returned to their living cages for an observation period of 2 weeks. During the 2-week observation period the body weight of the animals was frequently recorded.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC0

Effect level:

> 2.42 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other:

Remarks:

49-51 % 2.2 -Di-tert-butylperoxy butane in dibutyl phthalate

Mortality:

No mortality occurred during the 4-hour exposure period and the subsequent observation period of 14 days

Clinical signs:

other: No information on the behaviour of the rats during the exposure is available, because the animals were completely invisible as a consequence of the dense mist prevailing in the inhalation chamber.

Body weight:

The males and females gained weight in a normal way during the 14-day observation period.

Gross pathology:

Not examined.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Executive summary:

The maximum attainable concentration of the Trigonox D-B 50 (ca 50% di-tert-butyl sec-butylidene diperoxidea in dibutyl phtalate) aerosol in the test atmosphere turned out to be 2.42 mg/L air. Droplet size determinations in impaction samples revealed a maximum droplet diameter of 6.7 µm. Ninety per cent of the mist consisted o.f droplets with a diameter of 1.2-3.3 µm. No information on the behaviour of the rats during the exposure is available, because the animals were completely invisible as a consequence of the dense mist prevailing in the inhalation chamber. No mortality occurred during the 4-hour exposure period and the subsequent observation period of 14 days. The males and females gained weight in a normal way during the 14-day observation period.