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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
7th July 1997 to 8th September 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: A GLP compliant 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.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OTS 798.4100 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test

Test material

Constituent 1
Chemical structure
Reference substance name:
(R)-2,2,3-trimethylcyclopent-3-ene-1-acetaldehyde
EC Number:
224-815-8
EC Name:
(R)-2,2,3-trimethylcyclopent-3-ene-1-acetaldehyde
Cas Number:
4501-58-0
Molecular formula:
C10H16O
IUPAC Name:
(R)-2,2,3-trimethylcyclopent-3-ene-1-acetaldehyde
Details on test material:
- Name of test material (as cited in study report): Campholenic Aldehyde
- Physical state: clear, pale yellow liquid
- Storage condition of test material: 1 to 7ºC

In vivo test system

Test animals

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, IN 46229
- Weight at study initiation: 331 to 611 g
- Housing: individually in wire mesh cages
- Diet (e.g. ad libitum): Teklad Guinea Pig diet ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature: 64-79ºF
- Humidity (%): 30-70%
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
paraffin oil
Concentration / amount:
50 % w/v in the induction test group
25 % in the primary challenge
20 % in the rechallenge
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
paraffin oil
Concentration / amount:
50 % w/v in the induction test group
25 % in the primary challenge
20 % in the rechallenge
No. of animals per dose:
Twenty test animals, ten vehicle control animals, ten rechallenge naive control animals, twelve pilot animals. Equal numbers of male and females in each group.
Details on study design:
IRRITATION SCREENING (PILOT) TESTS:
The irritation potential of the test substance at levels if undiluted, 50%, 25%, 10%, 5%, 2.5%, 1% and 0.5% were evaluated with dilutions of test substance prepared w/v in Spectrum Mineral Oil Light. A second pilot test was performed at concentrations of 50%, 25%, 10% and 5% prepared w/v in Squibb Mineral Oil. Squibb was utilised in an effort to reduce irritation from the previous vehicle. Closed patches were applied to the animals with 0.3 mL of each test preparation applied into a 25 mm Hill Top Chamber®. Chambers were applied to the clipped surface of the animals as quickly as possible and occluded with rubber dental dam pulled taut and fastened to the bottom of the restrainer with clips. Approximately six hours later the dental dam and chambers were removed and the following day the irritation was scored.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: three
- Exposure period: approximately six hours
- Site: upper left flank of each animal following clipping the day before exposure.
- Frequency of applications: every seven days
- Duration: fourteen day period
- Concentrations: 50% w/v

B. PRIMARY CHALLENGE EXPOSURE
- Day(s) of challenge: fourteen days after last induction exposure
- Exposure period: approximately six hours
- Control group: one patch on right-hand side of animal body
- Site: skin site not previously exposed
- Concentrations: 25% w/v
- Evaluation (hr after challenge): see 'Any other information on materials and methods incl. tables'.

C. RECHALLENGE EXPOSURE
- Day(s) of challenge: animals exposed in primary challenge phase were again exposed fourteen days after the primary challenge
- Exposure period: approximately six hours
- Control group: ten naive animals which had never been exposed to the substance
- Site: skin site that had not been previously exposed. Test animals received one patch each of test substance and Squibb Mineral Oil on sites 4 and 5. Vehicle control animals received one patch each of test substance and Squibb Mineral Oil on sites 4, 5 or 6.
- Concentrations: 20% w/v
- Evaluation (hr after challenge): see 'Any other information on materials and methods incl. tables'.

OTHER: The same method of exposure as described under the pilot tests was used for the induction, challenge and rechallenge phases
Challenge controls:
Ten naive animals, were treated with the same test material concentration during the rechallenge phase. The test animals received one patch of the test material and one patch of the Squibb Mineral Oil using Sites 4 and 5. The vehicle control animals, common to this study received one patch of each test material and one patch of the Squibb Mineral Oil using Sites 4, 5, and 6.
Positive control substance(s):
no

Results and discussion

Any other information on results incl. tables

Irritation screening tests

Undiluted test substance produced grades of 1 with scabbing and blanching. The 50% w/v concentration in Spectrum Mineral Oil Light produced grades of 1 with blanching. The remaining test concentrations in the same vehicle produced grades of 1 and ±; additionally the 25% w/v concentration produced blanching and the 10% concentration produced scabbing on one site. The test concentrations in Squibb Mineral Oil all produced grades of 1 and ±.

A 50% w/v concentration in Squibb Mineral Oil was chosen for use as induction for 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 utilised as the vehicle control.

A 25% w/v concentration in Squibb Mineral Oil was chosen for use at primary challenge for the test group and vehicle control; this level was chosen as the highest concentration causing no more than slight primary irritation.

A 20% w/v concentration in Squibb Mineral Oil was chosen for use as rechallenge for the test group and naive control group; this level was chosen in an effort to reduce the irritation noted in controls.

Incidence and severity of responses

Table 1: Incidence and severity results

     Incidence of responses                             Mean severity scores   
     24 h   48 h  24 h  48 h
 Group  Test material  0  ±  1  2  3  0  ±  1  2  3    
 Primary Challenge                                       
 Test  TMID 25%  0  9  9  2  0  1  15  4  0  0  0.9  0.6
 Vehicle control  TMID 25%  0  9  1  0  0  0  10  0  0  0  0.6  0.5
 Rechallenge                                       
 Test  TMID 20%  0  8  10  2  0  1  13  5  1  0  0.9  0.7
   VMID-1  0  16  4  0  0  2  18  0  0  0  0.6  0.5
 Vehicle control  TMID 20%  0  9  1  0  0  0  10  0  0  0  0.5  0.5
   VMID-1  0  10  0  0  0  0  10  0  0  0  0.5  0.5

TMID: Campholenic aldehyde

VMID: Squibb Mineral Oil

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of the test, the test substance was determined to be a sensitiser using the Buehler method.
Executive summary:

The potential of Campholenic Aldehyde, as a 50% w/v formulation in Squibb Mineral Oil, to produce delayed contact hypersensitivity in guinea pigs was evaluated using an adaptation of the method of Rtiz and Buehler*.

Following primary challenge using Campholenic Aldehyde, as a 25% w/v formulation in Squibb Mineral Oil, the incidence of grade 2 responses in the test group (2 of 20) was compared to that of the vehicle control group (0 of 10). The incidence and severity of these responses in the test group were slightly greater than those produced by the vehicle control group indicating that the sensitisation had been induced. A rechallenge was conducted to evaluate the responses at a lower concentration in an effort to reduce the irritation level in the control group.

Following rechallenge using Campholenic Aldehyde, as a 20% w/v formulation in Squibb Mineral Oil, the incidence of the grade 2 responses in the test group (2 of 20) was compared to that of the naive control group (0 of 10). The incidence and severity of these responses in the test group were again greater than those produced by the naive control group confirming that sensitisation had been induced.

In conclusion, under the conditions of this test Campholenic Aldehyde was found to be a sensitiser.

*Ritz and Buehler, Current Concepts in Cutaneous Toxicity, ed. Drill and Lazar (Academic Press, 1980) pp. 25-40.