Registration Dossier

Administrative data

Description of key information

The median lethal doses of di-tert-butyl peroxide (CAS# 110-05-4) after single administration to rats, observed over a period of 14 days, are: oral LD50  greater than 2000 mg/kg body weight; acute dermal LD50 greater than 2000 mg/kg body weight; and acute inhalation LC50 (4 hr) greater than 22 mg/l (22000 mg/m3).

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
Reference
Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well-conducted study performed under GLP to current guideline with adequate test material characterization.
Qualifier:
according to
Guideline:
OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class method
Limit test:
yes
Species:
rat
Strain:
Wistar
Sex:
female
Details on test animals and environmental conditions:
Standard Laboratory Conditions. Air-conditioned with 10 - 15 air changes per hour, and continuously monitored environment with ranges for room
temperature 22 ± 3 °C and for relative humidity between 30 - 70% (values above 70% during cleaning process possible), automatically controlled light cycle of 12 hours light and 12 hours dark, music during the daytime light period.

Accommodation: In groups of three in Makrolon type-4 cages with wire mesh tops and standard softwood bedding (J. Rettenmaier & Söhne GmbH & Co. KG, 73494 Rosenberg / Germany, imported by Provimi Kliba AG, 4303 Kaiseraugst / Switzerland) including paper enrichment (Enviro-dri from Lillico, Biotechnology, Surrey / UK).

Diet: Pelleted standard Harlan Teklad 2914C rodent maintenance diet (Provimi Kliba AG, 4303 Kaiseraugst / Switzerland), batch no. 82/09 (B0770), was available ad libitum. Results of respective analyses for contaminants are included in Appendix I.

Water: Community tap-water from Itingen was available ad libitum in water bottles. Results of bacteriological assay, chemical and contaminant analyses of respective samples are included in Appendix II.
Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
The vehicle was chosen after a non-GLP solubility trial which was performed before the study initiation date. This formulation trial is excluded from the statement of compliance.

The dose formulations were prepared shortly before each dosing occasion using a magnetic stirrer.

The test item was weighed into a tared glass beaker on a suitable precision balance and the vehicle added (weight:volume). Homogeneity of the test item in the vehicle was maintained during administration using a magnetic stirrer. Food was provided again approximately 3 hours after dosing.
Doses:
The animals received a single dose of the test item by oral gavage administration at 2000 mg/kg body weight after being fasted for approximately 16.5 to 17.25 hours (access to water was permitted). The dosing volume was 10 mL/kg body weight.
No. of animals per sex per dose:
Six
Control animals:
no
Details on study design:
None
Statistics:
None
Sex:
female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Mortality:
No deaths occurred during the study.
Clinical signs:
In one female, slight shivering was noted 3 hours post treatment. Otherwise, no clinical signs were observed until the end of the observation period.
Body weight:
The body weight of the animals was within the range commonly recorded for this strain and age.
Gross pathology:
No macroscopic findings were recorded at necropsy.
Other findings:
None

None

Interpretation of results:
relatively harmless
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The median lethal dose of di-tert-butyl peroxide (CAS# 110-05-4) after single oral administration to female rats, observed over a period of 14 days is > 2000 mg/kg.
Executive summary:

Two groups, each consisting of three female RccHan:WIST (SPF) rats, were treated with di-tertbutyl peroxide (CAS# 110-05-4) by oral gavage administration at a dosage of 2000 mg/kg body weight. The test item was formulated in corn oil at a concentration of 0.2 g/mL and administered at a dosing volume of 10 mL/kg. The animals were examined daily during the acclimatization period and mortality, viability and clinical signs were recorded. All animals were examined for clinical signs within the first 30 minutes and approximately 1, 2, 3 and 5 hours after treatment on day 1 and once daily during test days 2-15. Mortality/viability was recorded within the first 30 minutes and approximately 1, 2, 3 and 5 hours after administration on test day 1 (with the clinical signs) and twice daily during days 2 - 15. Body weights were recorded on day 1 (prior to administration) and on days 8 and 15. All animals were necropsied and examined macroscopically. All animals survived until the end of the study period. In one female, slight shivering was noted 3 hours post treatment. Otherwise, no clinical signs were observed until the end of the observation period. The body weight of the animals was within the range commonly recorded for this strain and age. No macroscopic findings were recorded at necropsy. The median lethal dose of di-tert-butyl peroxide (CAS# 110-05-4) after single oral administration to female rats, observed over a period of 14 days is: LD50 (female rat): greater than 2000 mg/kg body weight

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
5 000 mg/kg bw
Quality of whole database:
Reliable without restrictions.

Acute toxicity: via inhalation route

Link to relevant study records
Reference
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.
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
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
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
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

  

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

 

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.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LC50
22 000 mg/m³
Quality of whole database:
Reliable without restrictions.

Acute toxicity: via dermal route

Link to relevant study records
Reference
Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10 Dec to 31 Dec 2009
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.
Qualifier:
according to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Qualifier:
according to
Guideline:
EU Method B.3 (Acute Toxicity (Dermal))
GLP compliance:
yes (incl. certificate)
Test type:
other: Standard acute dermal method
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
Animals: Rat, RccHanTM: WIST(SPF)
Rationale: Recognized by international guidelines as a recommended test system.
Breeder: Harlan Laboratories B.V.
Kreuzelweg 53
5961 NM Horst / The Netherlands
Total Number of Animals: 5 males and 5 females
Age at Treatment: Males: 8 weeks / Females: 12 weeks
Body Weight Range at Treatment: 241.1 g – 272.1 g (males) / 183.7 g – 208.9 g (females)
Identification: Unique cage number and corresponding color-coded spots on the tail. The animals were marked at acclimatization start.
Randomization: Selected by hand at time of delivery. No computer generated randomization program.
Acclimatization: Under laboratory conditions, after health examination. Only animals without any visible signs of illness were used for the study.
ENVIRONMENTAL CONDITIONS
Standard Laboratory Conditions. Air-conditioned with 10-15 air changes per hour, and continuously monitored environment with ranges for room temperature 22 ± 3 °C and for relative humidity between 30-70% (values above 70% during cleaning process possible), automatically controlled light cycle of 12 hours light and 12 hours dark, music during the daytime light period.
Type of coverage:
semiocclusive
Vehicle:
unchanged (no vehicle)
Details on dermal exposure:
One day before treatment, the backs of the animals were clipped with an electric clipper, exposing an area of approximately 10% of the total body surface.
Only those animals without injury or irritation on the skin were used in the test.
On test day 1, the test item was applied at a dose of 2000 mg/kg body weight evenly on the intact skin with a syringe and covered with a semi-occlusivedressing. The dressing was wrapped around the abdomen and fixed with an elastic adhesive bandage.
Application volume/kg body weight: 2 mL
Twenty-four hours after the application the dressing was removed and the skin was flushed with lukewarm tap water and drapped off with disposable paper towels. Thereafter, the reaction sites were assessed.
Duration of exposure:
24 hours
Doses:
2000 mg/kg body weight/day
No. of animals per sex per dose:
5 males / 5 females
Control animals:
not required
Details on study design:
Five male and five female RccHan:WIST (SPF) rats were treated with di-tert-butyl peroxide (CAS# 110-05-4) at 2000 mg/kg by dermal application. The test item was applied undiluted as delivered from the Sponsor at a volume dosage of 2 mL/kg. The application period was 24 hours.

The animals were examined daily during the acclimatization period and mortality, viability and clinical signs were recorded. All animals were examined for clinical signs within the first 30 minutes and at approximately 1, 2, 3 and 5 hours after treatment on day 1 and once daily during test days 2 - 15. Local signs were noted once daily from test day 2 - 15. Mortality/viability was recorded within the first 30 minutes and at approximately 1, 2, 3 and 5 hours after administration on test day 1 (with the clinical signs) and twice daily during days
2 - 15. Body weights were recorded on day 1 (prior to administration) and on days 8 and 15. All animals were necropsied and examined macroscopically.

NECROPSY:
All animals were killed at the end of the observation period by an intraperitoneal injection pentobarbitone at a dose of at least 2.0 mL/kg body weight and discarded after macroscopic examinations were performed. An external examination and opening of the abdominal and thoracic cavities for examinations of major organs were performed. The appearance of any macroscopic abnormalities was recorded. No organs or tissues were retained.

DATA COMPILATION:
Body weights were recorded on-line.

Mortality/viability, clinical and local dermal signs were compiled into the Tox Control Computer System during recording and/or recorded on data sheets.

Macroscopic findings were compiled into the Tox Control Computer System during recording.

The Tox Control Computer System (Tox Control-Lims) had been validated with respect to data collection, storage and retrievability.
Statistics:
None performed.
Sex:
male/female
Dose descriptor:
approximate LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Mortality:
No deaths occurred during the study.
Clinical signs:
No clinical signs were evident during the course of the study.
Body weight:
The body weight of the animals was within the range commonly recorded for this strain and age.
Gross pathology:
Dermal sores were noted on the skin of a single male rat (no. 1)
Other findings:
Generalized erythema, slight in degree, was noted in two males after removal of the semi-occlusive bandage 24 hours after administration. This finding persisted in one of the two males on the following day. Erythema was not seen in any animal from day 4 onwards.

Slight desquamation was noted in one male on the last two observation days.

No dermal changes were seen in the remaining two males or in the females.
Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The median lethal dose of di-tert-butyl peroxide (CAS# 110-05-4) after single dermal administration to rats of both sexes, observed over a period of 14 days (LD50) is greater than 2000 mg/kg body weight
Executive summary:

Five male and five female RccHan:WIST (SPF) rats were treated withdi-tert-butyl peroxide (CAS# 110-05-4)at 2000 mg/kg by dermal application. The test item was applied undiluted as delivered from the Sponsor at a volume dosage of 2 mL/kg. The application period was 24 hours.

 

The animals were examined daily during the acclimatization period and mortality, viability and clinical signs were recorded. All animals were examined for clinical signs withinthe first 30 minutesand at approximately 1, 2, 3 and 5 hours after treatment on day 1 and once daily during test days 2 - 15. Local signs were noted once daily from test day 2 - 15. Mortality/viability was recorded withinthe first 30 minutesand at approximately 1, 2, 3 and 5 hours after administration on test day 1 (with the clinical signs) and twice daily during days
2 - 15. Body weights were recorded on day 1 (prior to administration) and on days 8 and 15. All animals were necropsied and examined macroscopically.

 

No deaths occurred during the study.

 

No clinical signs were evident during the course of the study.

 

The body weight of the animals was within the range commonly recorded for this strain and age.

 

Local effects included slight generalized erythema initally in two males after removal of the semi-occlusive bandage 24 hours after administration. This finding persisted in one of the two males on the following day. Erythema was not seen in any animal from day 4 onwards. Slight desquamation was noted in one male on the last two observation days. No dermal changes were seen in the remaining two males or in the females.

 

Dermal sores were noted on the treated skin of one male (no. 1) and were considered to be related to the treatement with the test item.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LD50
2 000 mg/kg bw
Quality of whole database:
Reliable without restrictions.

Additional information

The actual LD50 and LC50 values are GREATER than the reference values. No fatalities occurred at the doses shown above.


Justification for selection of acute toxicity – oral endpoint
Apparently well conducted GLP study.

Justification for selection of acute toxicity – inhalation endpoint
Apparently well conducted GLP study.

Justification for selection of acute toxicity – dermal endpoint
Apparently well conducted GLP study.

Justification for classification or non-classification

The acute lethal values for oral, dermal and inhalation exposure are above the minimum classification levels.