Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
experimental starting date: 09-Mar-2010, experimental completion date: 30-Mar-2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Identification: di-tert-butyl peroxide
Description: Colorless liquid
CAS Number: 110-05-4
Batch Number: 0904130207
Purity: 99%
Expiry Date (Retest Date): 01-May-2011

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Laboratories Ltd, Kreuzelweg 53, 5961 NM Horst / Netherlands
- Age at study initiation: 9-10 weeks
- Weight at study initiation: males: 269.3 to 286.2 g, females: 178.1 to 187.9 g
- Fasting period before study: none
- Housing: nimals were housed in groups of 5 of the same sex in Makrolon® type-IV cages with wire mesh tops and standard softwood bedding ("Lignocel" J. Rettenmaier & Söhne GmbH & Co KG, 73494 Rosenberg / Germany, imported by Provimi Kliba AG, 4303 Kaiseraugst / Switzerland).
- Diet (e.g. ad libitum): Animals had ad libitum access to a pelleted standard Teklad rat maintenance diet (Provimi Kliba AG, 4303 Kaiseraugst, Switzerland) batch no. 82/09 except during the period when the animals were restrained in exposure tubes
- Water (e.g. ad libitum): Community tap water from Füllinsdorf ad libitum in water bottles, except during the period when they were restrained in exposure tubes.
- Acclimation period: at least five days under laboratory conditions, after clinical health examination

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C,
- Humidity (%): 30-70%
- Air changes (per hr):10-15
- Photoperiod (hrs dark / hrs light): 12/12

Animal Welfare:
This study was performed in an AAALAC-accredited laboratory in accordance with the Swiss Animal Protection Law under license no. 397

IN-LIFE DATES: From: To: 09-Mar-2010 to 23-Mar-2010

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
nose only
Vehicle:
clean air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The test atmosphere was generated using a Hudson nebulizer connected to a syringe pump. The polyethylene injector inside the nebulizer was replaced by a stainless steel injector
- Exposure chamber volume: not applicable
- Method of holding animals in test chamber: The animals were confined separately in restraint tubes which were positioned radially around the flow-past, nose-only exposure chamber
- Source and rate of air: compressed air was supplied by means of an oil free compressor and passed respiratory quality filters before it was introduced into the exposure system
- Method of conditioning air: respiratory quality filters
- System of generating particulates/aerosols: The test atmosphere was generated using a Hudson nebulizer connected to a syringe pump. The polyethylene injector inside the nebulizer was replaced by a stainless steel injector
- Method of particle size determination: not applicable
- Treatment of exhaust air: filtered
- Temperature, humidity, pressure in air chamber: 22.9 °C, 2.7 % rel humidity, 20.5 % oxygen

TEST ATMOSPHERE
- Brief description of analytical method used: Chemical determinations of vapor concentration were performed four times during exposure. The samples were drawn through a wash-bottle containing approximately 100 mL of Tetrahydrofuran. The wash-bottle was kept cool in water ice during sampling. An aliquot of each wash-bottle was forwarded in a cool box to the responsible scientist for analytical chemistry and stored frozen until analysis. The samples were analyzed using a GC method supplied by the Sponsor and implemented at Harlan Laboratories Ltd.
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle (if applicable):
- Concentration of test material in vehicle (if applicable):
- Justification of choice of vehicle:
- Lot/batch no. (if required):
- Purity:

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: as the test item was administered as a vapour no particle size determination was performed
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.):

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration:
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
nominal aerosol concentration was 22 mg/L air
chemical aerosol concentration was 23 mg/L air
No. of animals per sex per dose:
3
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations for viability were recorded once before exposure on the day of exposure (test day 1), three times during exposure, immediately and 1 h after exposure on test day 1 and twice daily during the observation period.
Each animal was examined three times during exposure, immediately and 1 h after exposure on test day 1 and once daily during the observation period. Observations were detailed and carefully recorded using explicitly defined scales as appropriate. Only grossly abnormal signs were detectable during exposure, as the animals were restrained in the exposure tubes. The body weight of each animal was recorded on test days 1 (before exposure), 2, 4, 8 and 15 (before necropsy).

- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight
Statistics:
no

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 22 mg/L air (nominal)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
none
Clinical signs:
Shivering and tachypnea during exposure were recorded in all animals. Tachypnea persisted until one hour after exposure end. Shivering was also recorded immediately after exposure end in all females. Ruffled fur was observed in all animals from 1 hour after exposure end until day 2. There were no clinical signs from test day 3 onwards.
Body weight:
From test day 1 to test day 2, slight body weight loss was noted in two males and one female. Stagnation of body weight was observed in one male and one female during the same period. Thereafter normal body weight development was recorded in these animals, except for two females. Slight body weight loss was recorded in one of these females and stagnation of body weight in the other female from test day 2 to test day 4.

There were no effects on body weight in the remaining female.
From test day 1 to test day 2, slight body weight loss was noted in two males and one female. Stagnation of body weight was observed in one male and one female during the same period. Thereafter normal body weight development was recorded in these animals, except for two females. Slight body weight loss was recorded in one of these females and stagnation of body weight in the other female from test day 2 to test day 4.
There were no effects on body weight in the remaining female.
Gross pathology:
There were no macroscopic findings.
Other findings:
none

Any other information on results incl. tables

  

Temperature, relative humidity and oxygen concentration during exposure were considered to be satisfactory for this type of study.

 Data on temperature, relative humidity and oxygen concentration are presented in the following table:

 

Recording Time

[hours:min]

Hours after exposure start

O2Concentration

[Vol %]

Temperature

[°C]

Relative Humidity

[% RH]

07:15

0:00

20.6

22.8

4.7

07:45

0:30

20.6

22.9

3.0

08:15

1:00

20.6

22.9

2.5

08:45

1:30

20.4

22.9

2.4

09:15

2:00

20.4

22.9

2.4

09:45

2:30

20.4

22.9

2.4

10:15

3:00

20.4

22.9

2.4

10:45

3:30

20.4

22.9

2.3

11:15

4:00

20.4

22.9

2.3

Mean

Mean

20.5

22.9

2.7

St. Dev.

St. Dev.

0.1

0.0

0.7

N

N

10

10

10

 

 

The nominal aerosol concentration was 22 mg/L air.The chemical aerosol concentration determined was 23 mg/L air as targeted.The aerosol concentration was stable during the exposure period.The nominal vapor concentration was slightly lower than the concentration determined chemically. This small difference was considered to be within the variation of the assay for chemical analysis and accordingly it was concluded that the efficiency was close to 100%.

Data on chemical concentration are presented in the following table:

 

Sampling Time

[hours:min]

Sampling Volume

[L]

Amount of Test Item in Washbottles

[mg]

Chemical Vapor Concentration

[mg/L air]

07:30 – 07:35

5.0

106.34 1

22

08:30 – 08:35

5.0

107.740

23

09:30 – 09:35

5.0

108.244

23

10:30 – 10:35

5.0

109.850

23

Mean

 

 

23

St. Dev.

 

 

0

N

 

 

4

 

Applicant's summary and conclusion

Interpretation of results:
study cannot be used for classification
Remarks:
Migrated information
Conclusions:
In conclusion, the LC50 of Di-tert-butyl Peroxide obtained in this study was estimated to be greater than 22 mg/L air (nominally determined mean aerosol concentration). There was no indication of relevant sex-related differences in toxicity of the test item.
Executive summary:

A group of three male and three female albino rats [RccHan:WIST(SPF)] was exposed by nose-only, flow-past inhalation for four hours to the test item at a chemically determined concentration of 23 mg/L air.All animals were observed for clinical signs and mortality during the inhalation exposure and theobservation period of 14 days. Body weights were recorded prior to exposure on test day 1, and during the observation period on test days 2, 4, 8 and 15 before necropsy. On day 15 all animals were sacrificed and necropsied.

The ranges of aerosol concentration, temperature, relative humidity, oxygen content and airflow rate measured during the exposure were considered to be satisfactory for a study of this type. In addition, the test item was considered to be respirable to rats.

 

All animals survived the scheduled observation period.

 

Tachypnea and shivering were recorded during exposure until 1 hour after exposure end. Ruffled fur was observed after exposure on test day 1 and test day 2. There were no clinical signs from test day 3 onwards.

 

There were slight effects on body weight from test day 1 to 4.

 

No macroscopic findings were recorded during necropsy.

 

In conclusion, the LC50 of di-tert-butyl peroxideobtained in this study was estimated to be greater than 22 mg/L air (nominally determined mean aerosol concentration). There was no indication of relevant sex-related differences in toxicity of the test item.