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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
The temperature and relative humidity (61-75°F and 31-75%, respectively) exceeded the preferred ranges (63-77°F and 30-70%, respectively) during the study. These occurrences are considered to have had no adverse effect on the outcome of the study.
GLP compliance:
yes (incl. certificate)
Type of study:
guinea pig maximisation test
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Hartley-derived albino guinea pigs were received at SLI from Hilltop Lab Animals, Inc., Scottdale, Pennsylvania.
- Age at study initiation: Young adult.
- Housing: The animals were housed individually in suspended stainless steel cages.
- Diet (e.g. ad libitum): PMI Certified Guinea Pig Chow was provided ad libitum throughout the study.
- Water (e.g. ad libitum): Municipal tap water, treated by reverse osmosis, was available ad libitum throughout the study.
- Acclimation period: Minimum of five days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 61-75°F
- Humidity (%): 31-75%.
- Air changes (per hr): 10-15 air changes/hour.
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark.

Route:
intradermal and epicutaneous
Vehicle:
propylene glycol
Concentration / amount:
Main study:
Induction phase: intradermal injection, 3% (w/w) in propylene glycol.
topical application, 100%.

Challenge phase: topical application, 100%
Route:
epicutaneous, semiocclusive
Vehicle:
propylene glycol
Concentration / amount:
Main study:
Induction phase: intradermal injection, 3% (w/w) in propylene glycol.
topical application, 100%.

Challenge phase: topical application, 100%
No. of animals per dose:
20 animals in test group, 10 animals in control group.
Details on study design:
RANGE FINDING TESTS:
The test article was then utilized at 100% and at 10%, 25% and 50% w/w in propylene glycol for the topical range-finding study and at 0.1%, 1%, 3% and 5% w/w in propylene glycol for the intrademal rangefinding study.


Topical Range-Finding Study: The results of the range-finding study indicated that a test article concentration of 100% was considered appropriate for topical induction.

Intradermal Range-Finding Study:
Due todosing difficulties at 5.0% intradermally and yet similar dermal responses observed at 3.0%, a test article concentration of 3.0% w/w in
propylene glycol was considered appropriate for intradermal induction.

MAIN STUDY
A. INDUCTION EXPOSURE
Intradermal induction:
On the day following clipping (day 0), three pairs of intradermal injections were made in the clipped area of ali sensitization study animals. The
injections were kept within an approximate 2 x 4 cm area with one row of three injections on each side of the back bone.
Injections for the test animals were:
a) 0.1 ml of Freund's Complete Adjuvant (FCA) emulsion
b) 0.1 ml of 3.0% test article in propylene glycol
c) 0.1 ml of 3.0% test article in FCA emulsion

Topical induction:
On the day prior to topical induction (day 6), the guinea pigs had the hair removed from the scapular area with a small animal clipper. Care was taken
to avoid abrading the skin during the clipping procedures. Following clipping, 0.5 mL of 10% w/w sodium lauryl sulfate in petrolatum was spread over the intradermal injection sites of all study animals.
On study day 7, any residual sodium lauryl sulfate preparation was removed with a dry gauze and the appropriate material was prepared and applied to the animals as indicated below:

0.15 g 100% test material (moistened with 10 drops propylene gycol)

Approximately 48 hours after dosing, the elastic wrap, tape and patch were removed. The test sites were wiped with gauze moistened in propylene
glycol to remove test article residue and the animals were retumed to their cages.


B. CHALLENGE EXPOSURE
On the day prior to challenge dose administration, the hair was removed from the right side of the test and challenge control animals with a small animal clipper. Care was taken to avoid abrading the skin during the clipping procedures.

On the following day (day 21), the appropriate concentration of the test article was prepared and applied to the appropriate animals as indicated below:
0.15 g 100% test material (moistened with 10 drops propylene gycol).











Challenge controls:
Intradermal induction:
Injections for the challenge and rechallenge control animals were as indicated below:
a: 0.1 mL of FCA emulsion
b: 0.1 mL of propylene glycol
c: 0.1 mL of 3.0% propylene glycol/FCA emulsion

Topical induction:
Challenge control: 0.8 mL of 100% propylene glycol.
Rechallenge control: 0.8 mL of of 100% propylene glycol.

Challenge:
Challenge control: 0.15 g 100% test material (moistened with 10 drops propylene gycol).
Positive control substance(s):
yes
Remarks:
alpha-Hexylcinnamaldehyde.
Positive control results:
Positive control: alpha-Hexylcinnamaldehyde.

Following topical induction and intradermal induction at 5.0% w/v alpha-Hexylcinnamaldehyde in propylene glycol and challenge at levels of 1.0% and 0.5% w/v alpha-Hexylcinnamaldehyde in propylene glycol, a contact sensitization response was observed, thereby demonstrating the susceptibility of the test system to this sensitizing agent.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100%
No. with + reactions:
16
Total no. in group:
20
Clinical observations:
No toxic symptoms were observed
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100%. No with. + reactions: 16.0. Total no. in groups: 20.0. Clinical observations: No toxic symptoms were observed.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100%
No. with + reactions:
16
Total no. in group:
20
Clinical observations:
No toxic symptoms were observed
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 100%. No with. + reactions: 16.0. Total no. in groups: 20.0. Clinical observations: No toxic symptoms were observed.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No toxic symptoms observed
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No toxic symptoms observed.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No toxic symptoms observed
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 100%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No toxic symptoms observed.

Following challenge with 100% test substance, some degree of sensitisation was noted in 16/20 test animals at the 24-hour and 48-hour scoring interval.

Group mean dermal scores were noted to be higher in the test animals as compared with the challenge control animals.

One animal was observed to have red extremities which was possibly an indication of a whole body sensitization response.

The sensitization study animals gained weight during the test period and generally appeared in good health.

Interpretation of results:
sensitising
Remarks:
Migrated information
Conclusions:
There was evidence of reactions indicative of skin sensitisation to the test substance under the conditions of the test and the substance is considered to be a sensitizer in guinea pigs.
Executive summary:

Method:

The dermal sensitization potential of the test substance was evaluated in Hartley-derived albino guinea pigs. Ten male and ten female guinea pigs received intradermal injections of 3.0% w/w test substance in propylene glycol along with injections of FCA and test substance in FCA. One week later, the test animals received a topical application of 100% test substance.

Challenge and rechallenge control animals received similar intrademnal and topical treatments except propylene glycol was used in place of the test substance. Following a two-week rest period, a challenge was performed whereby the twenty test and ten previously untreated (naive) challenge control guinea pigs were topically treated with 100% test substance. Challenge responses in the test animals were compared with those of the challenge control animals.

Resuts:

Test substance:

Following challenge with 100% test substance, some degree of sensitisation was noted in 16/20 test animals at the 24-hour and 48-hour scoring interval.

Group mean dermal scores were noted to be higher in the test animals as compared with the challenge control animals.

Positive control:

Following topical induction and intradermal induction at 5.0% w/v alpha-Hexylcinnamaldehyde in propylene glycol and challenge at levels of 1.0% and 0.5% w/v alpha-Hexylcinnamaldehyde in propylene glycol, a contact sensitization response was observed, thereby demonstrating the susceptibility of the test system to this sensitizing agent.

Conclusion:

There was evidence of reactions indicative of skin sensitisation to the test substance under the conditions of the test and the substance is considered to be a sensitizer in guinea pigs.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Skin sensitisation:

The dermal sensitization potential of the test substance was evaluated in Hartley-derived albino guinea pigs. Ten male and ten female guinea pigs received intradermal injections of 3.0% w/w test substance in propylene glycol along with injections of FCA and test substance in FCA. One week later, the test animals received a topical application of 100% test substance.

Challenge and rechallenge control animals received similar intrademal and topical treatments except propylene glycol was used in place of the test substance. Following a two-week rest period, a challenge was performed whereby the twenty test and ten previously untreated (naive) challenge control guinea pigs were topically treated with 100% test substance. Challenge responses in the test animals were compared with those of the challenge control animals.

Following challenge with 100% test substance, some degree of sensitisation was noted in 16/20 test animals at the 24-hour and 48-hour scoring interval.

Group mean dermal scores were noted to be higher in the test animals as compared with the challenge control animals.

There was evidence of reactions indicative of skin sensitisation to the test substance under the conditions of the test and the substance is considered to be a sensitizer in guinea pigs.


Migrated from Short description of key information:
There was evidence of reactions indicative of skin sensitisation to the test substance under the conditions of the test and the substance is considered to be a sensitizer in guinea pigs. Using the potency characterisation criteria in ECHA Guidance on Information Requirements and Chemical Safety Assessment, the substance is considered a moderate sensitiser. As no EC3 could be derived for sensitization, a qualitative approach to risk management must be adopted.

Justification for classification or non-classification

The substance is classified for skin sensitisation.

Following challenge with 100% test substance, some degree of sensitisation was noted in 16/20 test animals at the 24-hour and 48-hour scoring interval.

There was evidence of reactions indicative of skin sensitisation to the test substance under the conditions of the test and the substance is considered to be a sensitizer in guinea pigs.