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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:
2012-08-21 to 2012-10-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1992)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Version / remarks:
(2008)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
(1998)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
guinea pig maximisation test
Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, 97633 Sulzfeld, Germany
- Age at start of administration: 31 days
- Weight at start of administration: 258 – 316 g; Positive control group: 319 – 441 g
- Housing: The animals were kept in pairs in MAKROLON cages (MZK 80/25). Granulated textured wood was used as bedding material for the cages.
- Diet: Commercial diet, ssniff® R/M-H V1534 (Certificates of analysis provided) ad libitum
- Water: tap water ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):22°C ± 3°C
- Humidity (%): 55% ± 15%
- Air changes (per hr): 12 to 18-fold air change per hour
- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light (about 150 lux at approx. 1.50 m room height)

IN-LIFE DATES: From: August 21, 2012 To:October 12, 2012
Route:
intradermal and epicutaneous
Vehicle:
other: Sesame oil
Concentration / amount:
The concentrations of test substance in the main study (as determined in the preliminary test) were selected as follows:

Intradermal Induction: 10% suspension of Brassylic acid in sesame oil
Topical Induction: 50% suspension of Brassylic acid in sesame oil
Topical Challenge: 25% suspension of Brassylic acid in sesame oil
Route:
epicutaneous, occlusive
Vehicle:
other: Sesame oil
Concentration / amount:
The concentrations of test substance in the main study (as determined in the preliminary test) were selected as follows:

Intradermal Induction: 10% suspension of Brassylic acid in sesame oil
Topical Induction: 50% suspension of Brassylic acid in sesame oil
Topical Challenge: 25% suspension of Brassylic acid in sesame oil
No. of animals per dose:
Test group: 20 animals
Control group: 10 animals
Details on study design:
The concentrations of the test substance to be used at each stage of the main study were determined in a preliminary study. Eight animals were used for the preliminary test: 6 animals for the topical administration and 2 animals for the intracutaneous administration. The shoulder and the flank region of the animals were shaved or shaved and depilated (approx. 5 x 5 cm2). The allocation of different test sites of the animals was alternated in order to minimize site-to-site variations in response.

For intracutaneous exposure, 0.1 mL of the prepared test substance was administered intracutaneously (shoulder region). Three concentrations (0.01, 0.1 and 0.5%) of the test substance were injected intradermally into one animal and 3 further concentrations (1, 5, 10%) into a second animal.
For topical exposure, the test area of 3 animals each was shaved or shaved and depilated. 2 mL of the test item preparation was spread over a filter paper (2 cm x 4 cm) and applied to the test area and held in contact by an occlusive dressing. The concentrations of the test substance were 1, 5, 10 ,25 and 50% .

Two concentrations each were applied to the shaved or shaved and depilated flanks of 3 animals each. The occlusive dressing and the filter paper containing the test substance were removed after 24 or 48 hours and the application sites were assessed immediately, 24 and 48 hours (depilated) or immediately and 24 hours (non-depilated) after removal of the filter paper for erythema and oedema using the grading system listed in Annex I - Preliminary study results.

A. INDUCTION EXPOSURE

(Stage 1)

- No. of exposures: On Day 0, three pairs of intradermal injections of 0.1 mL were given in the shoulder region which was cleared of hair so that one of each pair lay on each side of midline.

- Exposure period: The skin reaction results of the first induction exposure were evaluated at 24 and
48 hours after beginning of exposure according to the MAGNUSSON/KLIGMAN grading scale in Table A1.

- Test groups: 20 animals
- Control group: 10 animals

- Site: the shoulder region. Injections (1) and (2) were given close to each other and nearest the head, while (3) was given towards the caudal part of the test area.

- Concentrations:
Test animals:
a) Freund's complete adjuvant (diluted 1 : 1 with 0.9% NaCl)
b) 10% suspension of Brassylic acid in sesame oil
c) the test substance in a 1:1 mixture (v/v) FCA/physiological saline (final concentration: 10 % Brassylic acid).

Control animals:
a) Freund's complete adjuvant (diluted 1 : 1 with 0.9% NaCl)
b) Sesame oil
c) Sesame oil in a 1:1 mixture (v/v) FCA/physiological saline

On Day 6, fur was shaved from the application area and the exposed skin was coated with 0.5 mL sodium laurylsulfate 10% in vaseline in order to induce a local irritation (irritation was not noted at 50% test substance in preliminary study).

(Stage 2)

Seven days after the intracutaneous injection, the shoulder region of the same animals (shaved one day before) was treated topically using the patch-test technique (exposure time: 48 hours). No cleaning of the skin was necessary. The skin reaction results were observed at 48 and 72 hours after beginning of exposure according to the MAGNUSSON/KLIGMAN grading scale in Table A1.

B. CHALLENGE EXPOSURE

(Stage 3)

- No. of exposures: one

- Day(s) of challenge: on Day 21

- Exposure period: On Day 21, flanks of the same animals were shaved and depilated for a further topical application using the patch-test technique. The filter paper containing the test substance was applied to the left flank, the filter paper with the vehicle to the right flank of the animal (exposure time: 24 hours). 21 hours after the filter paper had been removed, no cleaning of the treated skin was necessary.

- Test groups: 20 animals
- Control group: 10 animals

- Site: left flank was treated with the test substance, the right flank with the vehicle

- Concentrations:

a) 25% suspension of Brassylic acid in sesame oil (test group)
b) sesame oil (control group)

- Evaluation (hr after challenge): On Days 23 and 24: (i) 21 hours after removing the filter paper the challenge area was cleaned and cleared of hair if necessary (ii) three hours later (at 48 hours from the start of challenge application) the skin reaction was observed and recorded (iii) 24 hours after this observation a second observation (72 hours) was made and recorded. The skin reactions were graded according to the MAGNUSSON/KLIGMAN grading scale in (Table A1).

OTHER:

Positive control:
The animals of the positive control group (Guinea pig / Dunkin-Hartley) were treated with a 10% (v/v) α-hexyl cinnamic aldehyde solution intracutaneously in stage 1, undiluted α-hexyl cinnamic aldehyde topically in stage 2 and a 0.01% α-hexyl cinnamic aldehyde solution in stage 3.

Other observations:
Mortality and clinical signs: daily during the observation period
Body weight: at start of study and at study termination. Body weight was analysed statistically using STUDENT's t-test (p ≤0.01).
Positive control results:
The positive control group was not tested concurrently with this study but is a historical background group from a study performed during May 2012 (LPT 2013 (Table 1)) attachment.
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
25%
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 25%. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
25%
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 25%. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
25%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 25%. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
25%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 25%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Study report attachments:

LPT 2013 (Table 1 Skin reactions - main study)

LPT 2013 (Table 2 Bodyweights - main study)

LPT 2013 (Annex I - Preliminary study results)

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In this test system, Brassylic acid revealed no sensitising properties in guinea pigs according to MAGNUSSON and KLIGMAN.
Executive summary:

In a dermal sensitization study with Brassylic acid, Dunkin-Hartley guinea pigs were tested using the method of Magnusson and Kligman (Maximisation test).

In the preliminary study, 6 concentrations of Brassylic acid were tested by intracutaneous injection in 2 male animals: 0.01, 0.1, 0.5, 1, 5 or 10% suspensions in sesame oil: Concentrations up to 5% did not reveal any skin reactions. The concentration of 10% revealed a discrete or patchy erythema 24 hours after administration and was considered the maximum feasible applicable concentration. Six concentrations of Brassylic acid were tested by topical application in 6 male animals: 1, 5, 10, 25 and 50% suspensions in sesame oil. For the non-depilated skin group, no skin reactions were observed. In the depilated skin group, there were no skin reactions up to 25%.At 50% a discrete or patchy erythema was observed at 24 hours after start of exposure. Based on these results, the following concentrations were chosen for the main study: 10% concentration in sesame oil for the 1st (intracutaneous) stage, a 50% concentration for the 2nd (topical) induction stage and a 25% suspension in sesame oil for the challenge.

In the main study, 20 male test animals and 10 male control animals were used. For intradermal induction exposure, discrete or patchy erythema was observed in animals treated with 10% Brassylic acid in sesame oil concentration in all animals after 24 hours. In the preliminary study (epicutaneous induction exposure), it was noted that 2 mL of a 50% suspension of Brassylic acid in sesame oil/animal was not irritating to the shaved skin, so for the main study (epicutaneous induction exposure) the skin was coated with sodium laurylsulfate on the day before in order to induce a local irritation. This treatment resulted in a discrete or patchy erythema 48 and 72 hours after start of exposure in all test group animals. For the challenge phase of the study, 2 mL of a 25% suspension of Brassylic acid in sesame oil/animal (the maximum non-irritating concentration) revealed no skin irritation in any animal. The vehicle control revealed no skin reactions. The positive control group was not tested concurrently with this study but is a historical background group from a study performed during May 2012. Dunkin-Hartley guinea pigs treated with α-hexyl cinnamic aldehyde in sesame oil exhibited a sensitising reaction in all animals in form of a discrete or patchy erythema (grade 1).

There were no mortalities or clinical signs observed during the study. There were no statistically significant changes in body weight during the study. No necropsy was performed as no animal was found dead or was sacrificed in extremis. The results indicated that Brassylic acid was not a skin sensitiser at the challenge concentrations in any test animals. No reactions were noted in the negative control group. Brassylic acid is not a dermal sensitiser in this test system.

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

A skin sensitisation test in guinea pigs according to Magnusson and Kligman (Maximisation test) was available and was chosen as the key study. It was of acceptable quality and reliability with a Klimisch score of 1.

In the skin sensitisation test in guinea pigs according to Magnusson and Kligman (Maximisation test), Tridecanedioic acid did not produce any reaction in any test animals. The results from this study are acceptable to use in the human health risk assessment.


Migrated from Short description of key information:
Skin sensitisation: Not sensitising (OECD Guideline 406, skin sensitisation test in guinea pigs according to Magnusson and Kligman (Maximisation test) ; GLP)

Justification for selection of skin sensitisation endpoint:
Only 1 key study available.

Justification for classification or non-classification

Based on available information in the dossier, the substance tridecanedioic acid (CAS No. 505-52-2) does not need to be classified for skin sensitisation when the criteria outlined in Annex I of 1272/2008/EC and Annex I of Regulation 286/2011/EC are applied.