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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was conducted according to OECD Guideline 406 and GLPs.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
Stability, homogeneity, and achieved concentration of test substance in vehicle were not determined by analysis. These GLP deviations did not impact the outcome of the study.
Principles of method if other than guideline:
The test method is similar to that described by Buehler (1965).

Reference: Buehler EV. 1965. Delayed contact hypersensitivity in the guinea pig. Arch. Derm. 91:171-177.
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
The test method is similar to that described by Buehler (1965). Reference: Buehler EV. 1965. Delayed contact hypersensitivity in the guinea pig. Arch. Derm. 91:171-177.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
-Identity (according to study report): UNITAC 70
-Source: Union Camp Chemicals Limited
-Lot/Batch: 95040211
-Date of receipt: May 1995
-Physical state: Pelleted amber-colored solid
-CTL test substance reference number: Y09049/001
-Purity: 100% (data provided by Sponsor)
-Acid value: 131.6 mg KOH/g (data provided by Sponsor)

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Crl(HA)BR
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS:
-Source: Charles River UK Limited, Margate, Kent, UK
-Number of animals: 20 test and 10 control animals
-Age: young adults
-Acclimation period: at least 6 days
-Weight at study initiation: 376-495 g
-Housing: individually in suspended stainless-steel, wire mesh cages
-Diet: RGP Diet, supplied by Labsure, Manea, Cambridgeshire, UK, available ad libitum
-Water: Main water (automatic system) available ad libitum
-Identification: unique number written on a small area of clipped flank using a black waterproof marker pen and on the cage card identifying the contained animal

ENVIRONMENTAL CONDITIONS:
-Room temperature (°C): 17 ± 2
-Relative humidity (%): 55 ± 15
-Air changes: Approximately 25-30 changes/hour
-Lighting Cycle: Artificial, 12 hours light/12 hours dark

STUDY DATES:
The study was performed between June 1995 and July 1995.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
Topical induction: 30% (w/v) in corn oil
Challenge application: 3% and 10% (w/v) in corn oil
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
Topical induction: 30% (w/v) in corn oil
Challenge application: 3% and 10% (w/v) in corn oil
No. of animals per dose:
Test substance: 20 females
Control: 10 females
Details on study design:
SIGHTING STUDY:
The dose levels for the induction and challenge stages of this study were determined by a sighting study. Based on the results of this study, a 30% w/v preparation was chosen for the induction phase of the main study and 3% and 10% w/v preparations were chosen for the challenge phase of the main study.

INDUCTION PHASE:
An area (5 cm x 5 cm) on the scapular region of each animal was clipped free of hair. The test animals were administered a topical application of 0.4 mL of a 30% (w/v) preparation of the test substance in corn oil. The control animals received 0.4 mL of corn oil only. The preparations were applied to a lint patch (2 cm x 2 cm), placed on the application site and covered with adhesive tape. The patches were held in place by an elastic bandage (20-30 cm x 5 cm) and secured by a piece of PVC tape. The occlusive dressing was left in place for 6 hours. The induction procedure was repeated at the same site for the next two weeks, giving a total of three 6-hour exposures. The interval between each exposure was 7 days. The irritation response was noted approximately 1 day after the removal of each patch and before application of each subsequent patch. Animals were re-clipped prior to each of the applications. The animals were left untreated for two weeks following the last induction exposure.

CHALLENGE PHASE:
Two weeks after the last (third) induction, an area (15 cm x 5 cm) on both flanks of each animal were clipped free of hair. An occlusive dressing was prepared which consisted of two lint patches (1 cm x 2 cm) stitched to a piece of rubber sheeting (5 cm x 12 cm). A 10% (w/v) preparation of the test sample in corn oil (0.1-0.2 mL) was applied to one lint patch and a 3% (w/v) of the test substance in corn oil (0.1-0.2 mL) was applied to the remaining lint patch. The dressing was placed on the guinea pig so that the 10% preparation was on the left flank and the 3% preparation was on the right flank. The dressing was held in place by adhesive impermeable polyethylene tape for 6 hours. The dressings were removed and reactions were quantified at 24 and 48 hours after termination of exposure.

GRADING OF SKIN REACTIONS:
Each challenge site was examined 24 and 48 hours after removal of the patch. Reactions were scored according to the following scale:

Skin reaction
0 - No reaction
1 - Scattered mild redness
2 - Moderate and diffuse redness
3 - Intense redness and swelling

SENSITIZATION POTENTIAL:
Sensitization potential was determined by subtracting the percentage of animals responding in the control group from the percentage of animals responding in the test group, to give a net percentage response. The net response was compared using the following scheme:

0 = Not a sensitizer
1-8 = Weak sensitizer
9-28 = Mild sensitizer
29-64 = Moderate sensitizer
65-80 = Strong sensitizer
80-100 = Extreme sensitizer

BODY WEIGHTS:
Body weights were recorded on the day prior to dosing and at termination of the study.
Challenge controls:
Ten guinea pigs assigned to a control group received exposure doses of vehicle (at induction) and test material (at challenge) as described in details on study design.
Positive control substance(s):
yes
Remarks:
A positive control study using undiluted hexylcinnamaldehyde was carried out within 6 months of this study to ensure the test system continued to respond to a known sensitizer.

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Challenge: 3% test substance
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No skin reactions were evident.
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Challenge: 3% test substance. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions were evident..
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Challenge: 3% test substance
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No skin reactions were evident.
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Challenge: 3% test substance. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions were evident..
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Challenge: 10% test substance
No. with + reactions:
7
Total no. in group:
10
Clinical observations:
Moderate diffuse redness was noted in 2 of the 10 control animals and scattered mild redness was noted in 5 of the 10 control animals.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Challenge: 10% test substance. No with. + reactions: 7.0. Total no. in groups: 10.0. Clinical observations: Moderate diffuse redness was noted in 2 of the 10 control animals and scattered mild redness was noted in 5 of the 10 control animals..
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Challenge: 10% test substance
No. with + reactions:
5
Total no. in group:
10
Clinical observations:
Moderate diffuse redness was noted in 1 of the 10 control animals and scattered mild redness was noted in 4 of the 10 control animals.
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Challenge: 10% test substance. No with. + reactions: 5.0. Total no. in groups: 10.0. Clinical observations: Moderate diffuse redness was noted in 1 of the 10 control animals and scattered mild redness was noted in 4 of the 10 control animals..
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Challenge: 3% test substance
No. with + reactions:
1
Total no. in group:
20
Clinical observations:
Scattered mild redness was noted in 1 of the 20 test animals.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Challenge: 3% test substance. No with. + reactions: 1.0. Total no. in groups: 20.0. Clinical observations: Scattered mild redness was noted in 1 of the 20 test animals..
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Challenge: 3% test substance
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No skin reactions were evident.
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Challenge: 3% test substance. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No skin reactions were evident..
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Challenge: 10% test substance
No. with + reactions:
12
Total no. in group:
20
Clinical observations:
Scattered mild redness was noted in 12 of the 20 test animals.
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Challenge: 10% test substance. No with. + reactions: 12.0. Total no. in groups: 20.0. Clinical observations: Scattered mild redness was noted in 12 of the 20 test animals. .
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Challenge: 10% test substance
No. with + reactions:
5
Total no. in group:
20
Clinical observations:
Scattered mild redness was noted in 5 of the 20 test animals.
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Challenge: 10% test substance. No with. + reactions: 5.0. Total no. in groups: 20.0. Clinical observations: Scattered mild redness was noted in 5 of the 20 test animals..

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under conditions of this study, Rosin, reaction products with formaldehyde (CAS No. 91081-53-7) is not considered to be a sensitizer in female guinea pigs when tested using a method based on that described by Buehler (1965).

Under Directive 67/548/EEC, the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, and the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) guidelines, a response of 15% is required to consider a substance as positive when testing guinea pigs using a non-adjuvant test method. There were no signs of skin irritation in any animal during the induction phase of the study. When test animals and controls were challenged with a 10% w/v preparation of the test material, the response in control animals was greater than that seen in test animals. The net percentage response when animals were challenged with a 3% w/v preparation of the test material was 5%. Based on the results of this study, Rosin, reaction products with formaldehyde (CAS No. 91081-53-7) is not classifiable for skin sensitization according to UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.
Executive summary:

In a skin sensitization study performed using the method described by Buehler (1965), a group of 20 female guinea pigs was induced three times (once/week for 6 hours) by topical application of a 30% w/v preparation of UNITAC 70 (rosin, reaction products with formaldehyde) in a corn oil vehicle. A group of 10 female guinea pigs served as study controls and received only the vehicle during the three induction applications. All animals were challenged topically with concentrations of 3 and 10% w/v of the test material in the vehicle for an exposure period of 6 hours. Skin examinations at 24 and 48 hours after the completion of the challenge exposure indicated the test substance elicited an irritant response at the 10% challenge sites in both control and test animals. Since the response in control animals was greater than that observed in the test animals, this was considered to be an irritant rather than a sensitization response. At the 3% challenge sites, only a single test animal (1/20) had a slight skin response and no skin reactions were evident in the control group of animals. Under the conditions of this study, UNITAC 70 (rosin, reaction products with formaldehyde) was not considered to be a skin sensitizer in guinea pigs.