Di-tert-butyl peroxide

Endpoint summary

Description of key information

Di-tert-butyl peroxide was tested for sensitization using the Buehler method. It did not cause sensitization in this assay; therefore, it is not classified as a sensitizer.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well-conducted and documented study run according to accepted protocol. Report contains a COA for the test material.

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

Buehler test

Justification for non-LLNA method:

LLNA method was not yet adopted at time of study

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

Young adult, Hartley-derived albino guinea pigs were received from Harlan Sprague Dawley, Haslett, MI. Upon receipt, animals were examined, identified with plastic ear tags and then quarantined for a minimum of five days.

Animals chosen for study use were arbitrarily selected from healthy stock animals to avoid potential bias. All animals received a detailed pretest observation prior to dosing. Only healthy animals were chosen for study use. Females were nulliparous and non-pregnant.

Animals were housed individually in suspended stainless steel cages. Cage cards displaying at least the study number, animal number and sex were affixed to each cage. Animal room temperature and relative humidity ranges were 67 – 72 °F and 34-65%, respectively. Light timers were set to maintain a 12-hour light / 12-hour dark cycle. There were ten to twelve air changes in the animal room per hour. The animal room temperature and relative humidity were recorded a minimum of once daily.

Food: Purina Certified guinea Pig Chow #5026 was provided ad libitum to the animals throughout the study. The lot number and expiration date of each batch of diet used during the study were recorded. The feed was analyzed by the supplier for nutritional components and environmental contaminants. Dietary limitations for various environmental contaminants, including heavy metals, pesticides, polychrloinated biphenyls and total aflatoxin are set by the manufacturer. Within these limits, contaminants which may have been present were not expected to compromise the purpose of the study. Results of the dietary analyses (Certificates of Analysis) are provided by the manufacturer for each lot of diet. These are maintained by SLS.

Water: Municipal tap water treated by reverse osmosis or deionization (back-up system) was available to the animals ad libitum throughout the study. The purified drinking water was supplied by an automatic watering system. Monitoring of the drinking water for contaminants was conducted by SLS and the records are available for inspection. Within generally accepted limits, contaminants which may have been present were not expected to compromise the purpose of the study.

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Concentration / amount:

The test article was utilized at 100% and at 25%, 50% and 75% w/v in mineral oil for the range-finding study. For the sensitization study, the test article was utilized at 100% (induction) and 50% w/v in mineral oil (challenge).

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Concentration / amount:

The test article was utilized at 100% and at 25%, 50% and 75% w/v in mineral oil for the range-finding study. For the sensitization study, the test article was utilized at 100% (induction) and 50% w/v in mineral oil (challenge).

No. of animals per dose:

Two per sex for the range finding study; ten per sex for the sensitization study.

Details on study design:

Induction

Dosing: On the day prior to first induction dose administration, the hair was removed from the left side of the twenty test animals with a small animal clipper. Care was taken to avoid abrading the skin during clipping procedures. On the following day (Day 0), the appropriate concentration of the test article was prepared and applied to the animals as indicated below:

Induction number: 1, 2, 3
Test site numbers: 1, 3, 5
Concentration: 100%
Amount applied: 0.4 ml
Patch design: 2 x 2 cm Webril patch
Number of animals (male/female): 10/10

Following patch application, the trunk of the animal was wrapped with elastic wrap which was secured with adhesive tape to prevent removal of the patch and the animal was returned to its cage. Approximately six hours after patch application, the elastic wrap, tape and patches were removed. The test sites were then wiped with gauze moistened in distilled water to remove test article residue. The animals were then returned to their cages.

Dosing: On the day prior to challenge dose administration, the hair was removed from the right side of the twenty test animals and ten challenge control animals with a small animal clipper. Care was taken to avoid abrading the skin during clipping procedures. On the following day (Day 27), the appropriate concentration of the test article was prepared and applied to the animals as indicated below:

Test animals
Test site number: 2
Concentration: 50% w/v in mineral oil
Amount applied: 0.4 ml
Patch design: 2 x 2 cm Webril patch
Number of animals (male/female): 10/10

Challenge controls:

Challenge animals
Test site number: 2
Concentration: 50% w/v in mineral oil
Amount applied: 0.4 ml
Patch design: 2 x 2 cm Webril patch
Number of animals (male/female): 5/5

Positive control substance(s):

yes

Remarks:

hexyl cinnamaldehyde (historical control)

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

12

Total no. in group:

20

Clinical observations:

Positive reactions were graded +/- and assigned a value of 0.5 for calculation.

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50%. No with. + reactions: 12.0. Total no. in groups: 20.0. Clinical observations: Positive reactions were graded +/- and assigned a value of 0.5 for calculation..

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

4

Total no. in group:

20

Clinical observations:

Positive reactions were graded +/- and assigned a value of 0.5 for calculation.

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 4.0. Total no. in groups: 20.0. Clinical observations: Positive reactions were graded +/- and assigned a value of 0.5 for calculation..

The results of the range-finding study indicated that a test article concentration of 100% produced a mild dermal response and was, therefore, considered appropriate for induction. The highest nonirritating concentration was determined to be 50% and this was considered appropriate for challenge.

Following induction 1 with 100% di-t-butyl peroxide, dermal scores of 1 (some with very slight edema) were noted in 9/20 and 8/20 test animals at the 24 and 48 hour scoring intervals, respectively. Following inductions 2 and 3 at the same concentration, the dermal responses were similar to induction 1. Dermal scores of 1 (some with very slight edema) were noted in 18/20 and 14/20 test animals at the 24 and 48 hour scoring intervals, respectively, at induction 2 and in 14/20 test animals at both the 24 and 48 hours scoring intervals at induction 3.

 

Following challenge with 50% w/v di-t-butyl peroxide in mineral oil, dermal scores of 0 were noted to be similar in the test animals as compared to the challenge control animals.

 

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results of this study, di-t-butyl peroxide is not considered to be a contact sensitizer in guinea pigs. The results of the hexylcinnamaldehyde historical control demonstrates that the test design utilized could detect potential mild to moderate contact sensitizers.

Executive summary:

The dermal sensitization potential of di-t-butyl peroxide was evaluated in Hartley-derived albino guinea pigs. Ten male and ten female guinea pigs were topically treated with 100% di-t-butyl peroxide, once per week, for three consecutive weeks. Following a two week rest period, a challenge was performed whereby the twenty test and ten previously untreated (naïve) challenge control guinea pigs were topically treated with 50% w/v di-t-butyl peroxide in mineral oil. Challenge responses in the test animals were compared to those of the challenge control animals.

 

Following induction 1 with 100% di-t-butyl peroxide, dermal scores of 1 (some with very slight edema) were noted in 9/20 and 8/20 test animals at the 24 and 48 hour scoring intervals, respectively. Following inductions 2 and 3 at the same concentration, the dermal responses were similar to induction 1. Dermal scores of 1 (some with very slight edema) were noted in 18/20 and 14/20 test animals at the 24 and 48 hour scoring intervals, respectively, at induction 2 and in 14/20 test animals at both the 24 and 48 hours scoring intervals at induction 3. Following challenge with 50% w/v di-t-butyl peroxide in mineral oil, dermal scores of 0 to+were noted to be similar in the test animals as compared to the challenge control animals.

 

Using hexylcinnamaldehyde as a mild to moderate positive control, Springborn Laboratories, Inc.,,, has compiled historical control data for contact sensitization to this agent utilizing the test system described herein (modified Buehler design). As indicated, 16.7% of animals induced with hexylcinnamaldehyde elicited a contact sensitization response following challenge with hexylcinnamaldehyde and 50% of animals induced with hexylcinnamaldehyde elicited a contact sensitization response following rechallenge with hexylcinnamaldehyde, thereby demonstrating the susceptibility of the test system to this sensitizing agent.

 

Based on the results of this study, di-t-butyl peroxide is not considered to be a contact sensitizer in guinea pigs. The results of the hexylcinnamaldehyde historical control demonstrates that the test design utilized could detect potential mild to moderate contact sensitizers.

Reference 2

Endpoint:

skin sensitisation: in vitro

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Does not meet the criteria for classification based on a valid sensitization study.