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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1996-04-10 to 1996-05-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study; OECD guideline was followed
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
adopted 17 July 1992
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc., P.O. Box 29176; Indianapolis, Indiana 46229
- Age at study initiation: young adult
- Weight at study initiation: 373 to 681 g
- Housing: individually housed in wire mesh suspension cages
- Diet: teklad guinea pig diet; ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark cycle

Route:
epicutaneous, occlusive
Vehicle:
other: Squibb mineral oil
Concentration / amount:
- Induction: 50 % of the test item; undiluted: vehicle control
- Challenge: 50 % of the test item; 50 % of the vehicle
Route:
epicutaneous, occlusive
Vehicle:
other: Squibb mineral oil
Concentration / amount:
- Induction: 50 % of the test item; undiluted: vehicle control
- Challenge: 50 % of the test item; 50 % of the vehicle
No. of animals per dose:
10 guinea pig per sex
Details on study design:
RANGE FINDING TESTS: The irritation potential of the test item at levels of 50 %, 25 %, 10 % and 5 %, was evaluted in a single group of four animals, such that each animal in a given pilot group was exposed to the same levels. In additional pilot, repeating the concentrations evaluated in pilot 1 plus four additional concentrations of 2.5 %, 1 %, and 0.5 % and undiluted Squibb mineral oil. All formulations were prepared w/v in Squibb mineral oil. The 50%, 25 %, 10 %, and 10 %, and 5 % formulation produced grades of +/-. The 2.5 %, 1 %, and 0.5 % formulations and the undiluted Squibb mineral oil produced grades of 1 and +/-.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: six-hour exposures (+/- 15 minutes)
- Test groups: 50 % of the test item
- Control group: undiluted vehicle
- Site: left shoulder
- Frequency of applications: thrice (once every seven days for fourteen days)
- Duration: six hour
- Concentrations: 50 %

B. CHALLENGE EXPOSURE
- No. of exposures: 3
- Day of challenge: 28
- Exposure period: once
- Test groups: 50 % of the test item
- Control group: 50 % of the test item
- Site: left flank
- Concentrations: 50 %
- Evaluation (hr after challenge): 24, 48 hour

Challenge controls:
no
Positive control substance(s):
yes
Remarks:
historical data
Positive control results:
The animals were induced by 1 exposure with 0.3 % (ethanol) 1-chloro-2,4-dinitrobenzene. The animals were induced by 3 exposures at weekly intervals with 2.5 % (ethanol) alpha-hexylcinnamaldehyde.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
50 %
No. with + reactions:
9
Total no. in group:
20
Clinical observations:
slight but confluent, or moderate patchy erythema
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50 %. No with. + reactions: 9.0. Total no. in groups: 20.0. Clinical observations: slight but confluent, or moderate patchy erythema.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50 %. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
50 %
No. with + reactions:
4
Total no. in group:
10
Clinical observations:
slight but confluent, or moderate patchy erythema
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 50 %. No with. + reactions: 4.0. Total no. in groups: 10.0. Clinical observations: slight but confluent, or moderate patchy erythema.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
50 %
No. with + reactions:
1
Total no. in group:
10
Clinical observations:
slight but confluent, or moderate patchy erythema
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 50 %. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: slight but confluent, or moderate patchy erythema.
Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Following primary challenge using cyclohexylidenebis[tert-butyl]peroxide, as a 50 % w/v formulation in Squibb mineral oil, the incidence of grade 1 responses in the test group (9 of 20) was compared to that of the vehicle control group (4 of 10). The incidence and severity of these responses in the test group were essentially comparable to those produced by the vehicle control group indicating that sensitization had not been induced.
Executive summary:

Cyclohexylidenebis[tert-butyl]peroxide was tested in the Buehler test with guinea pigs according to OECD guideline no. 406. A 50 % w/v concentration of the test item, in Squibb mineral oil was chosen for occlusive epidermal induction of the test group. This level was chosen as the highest concentration causing no greater than mild to moderate primary irritation. Undiluted Squibb mineral oil was utilized at induction for the vehicle control group. The procedure was repeated at the same site once every seven days for fourteen days for a total of three approximate six-hour exposures.

A 50 % w/v concentration of cyclohexylidenebis[tert-butyl]peroxide, in Squibb mineral oil was chosen for epidermal application at primary challenge for the test group and the vehicle control group. This level was chosen as the highest concentration causing no more than slight primary irritation.

Following primary challenge using cyclohexylidenebis[tert-butyl]peroxide, as a 50 % w/v formulation in Squibb mineral oil, the incidence of grade 1 responses in the test group (9 of 20) was compared to that of the vehicle control group (4 of 10). The incidence and severity of these responses in the test group were essentially comparable to those produced by the vehicle control group indicating that sensitization had not been induced.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Cyclohexylidenebis[tert-butyl]peroxide was tested in the Buehler test with guinea pigs according to OECD guideline no. 406. A 50 % w/v concentration of the test item, in Squibb mineral oil was chosen for occlusive epidermal induction of the test group. This level was chosen as the highest concentration causing no greater than mild to moderate primary irritation. Undiluted Squibb mineral oil was utilized at induction for the vehicle control group. The procedure was repeated at the same site once every seven days for fourteen days for a total of three approximate six-hour exposures.

A 50 % w/v concentration of cyclohexylidenebis[tert-butyl]peroxide, in Squibb mineral oil was chosen for epidermal application at primary challenge for the test group and the vehicle control group. This level was chosen as the highest concentration causing no more than slight primary irritation.

Following primary challenge using cyclohexylidenebis[tert-butyl]peroxide, as a 50 % w/v formulation in Squibb mineral oil, the incidence of grade 1 responses in the test group (9 of 20) was compared to that of the vehicle control group (4 of 10). The incidence and severity of these responses in the test group were essentially comparable to those produced by the vehicle control group indicating that sensitization had not been induced.


Migrated from Short description of key information:
Cyclohexylidenebis[tert-butyl]peroxide, as a 50 % w/v formulation in Squibb mineral oil, was tested for skin sensitizing properties in a Buehler assay with guinea pigs. The incidence and severity of the responses in the test group were essentially comparable to those produced by the vehicle control group indicating that sensitization had not been induced.

Justification for selection of skin sensitisation endpoint:
Only one GLP and guideline study available.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available study the test item is not classified for skin sensitization according to Regulation (EC) No 1272/2008 (CLP) .