Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)

Data source

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

Materials and methods

Principles of method if other than guideline:
EEC Methods for the determination of toxicity, Annex of Directive92/69/EEC (OJ No. L383A, 29.12.92), Part B. Method B6. Skin Sensitization. Guinea Pig Maximisation test described by MAGNUSSON, B. and KLIGMAN, A.M. (1970) Allergic Contact Dermatitis in the Guinea Pig: Identification of Contact Allergens, Thomas, C.C., Springfield, Illinois, U.S.A.
GLP compliance:
yes
Type of study:
guinea pig maximisation test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
Fifteen male albino guinea-pigs (Dunkin/Hartley) from D. Hall, Newchurch, Staffordshire, England were 4-5 weeks of age and weighed 288-327 g and were acclimatised to the facility for 13 days prior to allocation to the main study. An additional 8 animals, from the same supplier, were used for the preliminary investigation. Each animal was identified by a unique ear tattoo number. The animals were housed in groups of in suspended metal cages with wire mesh floors. Each cage was identified by colored label displaying the study number, animal numbers, Study Director initials and Home Office license. A vitamin C enriched guinea-pig diet (FD2) and drinking water were provided ad libitum. Hay was given weekly. The study diet was not analyzed for nutrients, possible contaminants or micro-organisms. Animal room was maintained at approximately 21 degrees C and relative humidity at 30-70%. Air exchange was maintained at approximately 15 air changes per hour and lighting was controlled via electric timer to give 12 hours light (0700-1900 hours) in each 24-hour period. Environmental parameters were recorded daily.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
other: A product of coconut oil, supplied by Alembic Products, Saltney, Chester, England.
Concentration / amount:
Induction intradermal injection - 20% v/v in Alembicol D. This was the highest practical concentration that could be dosed intradermally and did not adversely affect the animals.
Induction topical application - as supplied. This was the highest practical concentration that could be dosed topically and did not give rise to irritating effects.
Topical challenge — as supplied and 50% v/v in Alembicol D. From preliminary investigations Isodecyl benzoate, as supplied, was the highest practical concentration and did not give rise to irritating effects.

Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: A product of coconut oil, supplied by Alembic Products, Saltney, Chester, England.
Concentration / amount:
Induction intradermal injection - 20% v/v in Alembicol D. This was the highest practical concentration that could be dosed intradermally and did not adversely affect the animals.
Induction topical application - as supplied. This was the highest practical concentration that could be dosed topically and did not give rise to irritating effects.
Topical challenge — as supplied and 50% v/v in Alembicol D. From preliminary investigations Isodecyl benzoate, as supplied, was the highest practical concentration and did not give rise to irritating effects.

No. of animals per dose:
There were 5 Control animals and 10 Test animals.
Details on study design:
RANGE FINDING TESTS:
The intradermal and topical irritancy of a range of dilutions of the test substance was investigated to identify where possible (a) concentrations of the test substance that would produce irritation suitable for the induction phase of the main study and (b) a maximum non-irritant concentration by the topical route of administration for the challenge phase.
Animals for these investigations were pre-treated with an intradermal injection of Freund’s complete adjuvant, 50:50 with water for irrigation (Ph. Eur), approximately one week prior to the start of the preliminary investigations.

MAIN STUDY
A. INDUCTION EXPOSURE
Induction intradermal injections - test animals
A 40 x 60 mm area of dorsal skin on the scapular region of the guinea-pig was clipped free of hair with electric clippers. Three pairs of intradermal injections were made into a 20 x 40 mm area within the clipped area.
Injectables for the test animals were prepared as follows:
1. Freund’s complete adjuvant (Difco Laboratories, Detroit 1, Michigan, U.S.A.) was diluted with an equal volume of water for irrigation (Ph.Eur.).
2. Isodecyl benzoate, 20% v/v in Alembicol D.
3. Isodecyl benzoate, 20% v/v in a 50 : 50 mixture of Freund’s complete adjuvant and Alembicol D.
Induction topical application - test animals
The preliminary investigations indicated that the maximum practical concentration of the test substance for topical application (as supplied) did not produce skin irritation. Therefore, six days after the injections, the same 40 x 60 mm interscapular area was clipped and shaved free of hair and the site was pre-treated by gentle rubbing with 0.5 ml per site of 10% w/w sodium lauryl sulphate in petrolatum. Twenty-four hours later a 20 x 40 mm patch of Whatman No. 3 paper was saturated with approximately 0.4 ml of Isodecyl benzoate, as supplied. The patch was placed on the skin of the test animals and covered by a length of impermeable plastic adhesive tape (50 mm width “Blenderm”). This in turn was firmly secured by elastic adhesive bandage (50 mm width “Elastoplast”) wound round the torso of the animal and fixed with “Sleek” impervious plastic adhesive tape. The dressing was left in place for 48 hours.

Induction - control animals
During the induction phase, the control animals were treated similarly to the test animals with the exception that the test substance was omitted from the intradermal injections and topical application.

B. CHALLENGE EXPOSURE
Challenge - control and test animals
The control and test animals were challenged topically two weeks after the topical induction application using Isodecyl benzoate, as supplied and 50% v/v in Alembicol D. Hair was removed by clipping and then shaving from an area on the left flank of each guinea-pig. A 20 x 20 mm patch of Whatman No. 3 paper was saturated with approximately 0.2 ml of Isodecyl benzoate, as supplied and applied to an anterior site on the flank. Isodecyl benzoate, 50% v/v in Alembicol D was applied in a similar manner to a posterior site. The patches were sealed to the flank for 24 hours under strips of “Blenderin” covered by “Elastoplast” wound round the trunk and secured with “Sleek”.
Challenge controls:
The sensitivity of the guinea-pig strain was checked periodically at the laboratory with hexyl cinnamic aldehyde, a known sensitiser. Recent test results were included in the report.
Positive control substance(s):
yes
Remarks:
Hexyl cinnamic aldehyde.

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Isodecyl benzoate - neat
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
negative
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Isodecyl benzoate - neat. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: negative.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Isodecyl benzoate 50%v/v in Alembicol
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
negative
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Isodecyl benzoate 50%v/v in Alembicol. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: negative.
Reading:
1st reading
Hours after challenge:
24
Group:
other: Freund's Treated Controls
Dose level:
Control
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
negative
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Isodecyl benzoate - neat
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
negative
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Isodecyl benzoate - neat. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: negative.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Isodecyl benzoate 50%v/v in Alembicol
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
negative
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Isodecyl benzoate 50%v/v in Alembicol. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: negative.
Reading:
2nd reading
Hours after challenge:
48
Group:
other: Freund's Treated Controls
Dose level:
Control
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
negative
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
In this study, Isodecyl benzoate did not produce evidence of skin sensitisation (delayed contact hypersensitivity) in any of the ten test animals.
Executive summary:

Skin sensitisation potential of Isodecyl benzoate was assessed in the guinea-pig according to EEC Methods for the determination of toxicity, Annex of Directive 92/69/EEC (OJ No. L383A, 29.12.92), Part B, Method B.6. Skin sensitisation. Based on the results of a preliminary irritation test, fifteen male albino guinea-pigs (Dunkin/Hartley) were treated by intradermal injection (20% Isodecyl benzoate v/v in Alembicol D and 20% v/v in a 50:50 mixture of Freund’s complete adjuvant and Alembicol D) and further sensitized by a 48-hr topical application (20 x 40 mm patch of Whatman No. 3 paper saturated with approximately 0.4 ml of Isodecyl benzoate, as supplied). For the induction phase of control animals, treatments were similar to those for the test animals with the exception that the test substance was omitted from the intradermal injections and topical application. Control and test animals were challenged topically two weeks after the induction using Isodecyl benzoate, as supplied, and 50% v/v in Alembicol D. During the induction phase, necrosis was recorded at sites receiving Freund’s Complete Adjuvant (intradermal injection) in test and control animals and slight irritation was seen in test animals at sites receiving Isodecyl benzoate, 20% v/v in Alembicol D and in control animals receiving Alembicol D. After topical application in the induction phase, slight erythema was observed in test animals following topical application with Isodecyl benzoate, as supplied and in the control guinea-pigs. During the challenge phase, no dermal reactions were seen in any of the test or control animals. Based on these results,isodecyl benzoate did not produce evidence of skin sensitisation (delayed contact hypersensitivity) in any of the ten test animals and does not require labeling with the risk phrase R43 "May cause sensitization by skin contact” in accordance with Council Directive 79/831/EEC Annex VI, Part 11(D) as described in Commission Directive 93/21/EEC.