2,2'-azobis[2-methylbutyronitrile]

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: low respirability of atmosphere noted. This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labeling and/or risk assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

only males were exposed

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,2'-azobis[2-methylbutyronitrile]

EC Number:

236-740-8

EC Name:

2,2'-azobis[2-methylbutyronitrile]

Cas Number:

13472-08-7

Molecular formula:

C10H16N4

IUPAC Name:

2,2'-diazene-1,2-diylbis(2-methylbutanenitrile)

Details on test material:

- Purity: >98 %

Test animals

Species:

rat

Strain:

other: Crl:CD®

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 7-8 week
- Weight at study initiation: 232-250 g
- Fasting period before study: No
- Housing: Singly in stainless steel, wire mesh cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 1 week

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: dust

Type of inhalation exposure:

nose only

Vehicle:

other: air

Details on inhalation exposure:

Generation: Dust atmospheres were generated with a 3-stage, hourglass-shaped system. A round flask at the bottom of the generator served as a dust reservoir. A cyclone-shaped flask, inserted above the reservoir, served as an elutriator. A cylindrical flask, inserted between the elutriator and the exposure chamber, served as a settling chamber to remove large particles. A motorized stirring rod with plastic paddles agitated dust in the generator. During the last exposure, surface vibrators were added to keep dust from accumulating on the generator’s walls. Air introduced as the bottom of the generator carried dust particles upward to the elutriator. Dilution air introduced at the elutriator swept airborne dust through the settling chamber and into the exposure chamber. Dust concentration was controlled by varying the two airflows.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

At 15- to 30-minute intervals, calibrated volumes of test atmosphere were drawn through pre-weighed glass fiber filters. Filters were weighed on a Cahn 26 Automatic Electrobalance®. Atmospheric concentration was determined from filter weight gain.

Duration of exposure:

4 h

Concentrations:

1.8, 3.7, and 8.9 mg/L

No. of animals per sex per dose:

6 males per dose

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days, weekends included when deemed necessary
- Frequency of observations and weighing: Daily
- Necropsy of survivors performed: No

Statistics:

None reported

Results and discussion

Effect levels

Sex:

male

Dose descriptor:

other: ALC

Effect level:

> 8.9 mg/L air

Exp. duration:

4 h

Mortality:

No mortality was observed.

Clinical signs:

other: During exposure, rats’ faces were covered with test material. Rats exposed to 1.8 mg/L exhibited no response to sound. At higher concentrations, observations could not be made due to the dense dust atmosphere in the chamber. Rats exposed to 1.8 and 3.7 m

Body weight:

All rats exhibited slight to severe weight loss 1 day post exposure. At 8.9 mg/L, 1 rat continued to lose weight for 1 more day. Weight loss was followed by normal weight gain.

Gross pathology:

Not performed.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

This study and the conclusions which are drawn from it fulfill the quality criteria (validity, reliability, repeatability).
The lethal concentration of the test substance is greater than 8.9 mg/L.

Executive summary:

Groups of 6 male Crl:CD® rats were exposed to dust atmospheres of the test substance for single, 4-hour periods. The lethal concentration of the test substance as supplied is greater than 8.9 mg/L, the highest concentration that could be generated. Because of the atmospheres' low respirability, this test should be considered a hazard evaluation of the material as supplied, rather than an accurate toxicity evaluation.