Fatty acids, C18-unsatd.

Skin sensitisation

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:

weight of evidence

Study period:

26 Apr - 25 May 1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study

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

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

Azelaic acid

EC Number:

204-669-1

EC Name:

Azelaic acid

Cas Number:

123-99-9

IUPAC Name:

azelaic acid

Details on test material:

- Name of test material (as cited in study report): Azelaic acid
- Physical state: white powder
- Analytical purity: no data
- Storage condition of test material: under ambient conditions

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Olac
- Weight at study initiation: 318 - 347 g
- Acclimation period: 4 days

Animal room environmental measurements showed, the temperature and humidity were maintained between the specified limits for the duration of the study.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: Acetone/PEG400

Induction 2

Concentration / amount:

Induction application: 0.25 % (intradermal) and 50.0 % (epicutanous)
Challenge application: 50.0 % (epicutanous)

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: Acetone/PEG400

Challenge 2

Concentration / amount:

Induction application: 0.25 % (intradermal) and 50.0 % (epicutanous)
Challenge application: 50.0 % (epicutanous)

No. of animals per dose:

10

Details on study design:

RANGE FINDING TESTS:
Intradermal injection: Preliminary irritation studies were carried out to determine concentrations of test material suitable for sensitization challenge: Four male guinea pigs weighing between 348-374 g at the start of the study were injected intradermally on the clipped flanks with 0.1 mL aliquots of 2.0, 1.0, 0.5, 0.25, 0.1, 0.05 % (w/v) test material in corn oil. Approximately 24 hours later the reactions were examined for size in millimetres (length and breath), erythema and oedema.
Occluded patch: Four male guinea pigs weighing between 501-514 g were selected. For each guinea pig three eight millimetre diameter filter paper patches were saturated with the following concentrations: 1.0, 5.0, 10.0 % (w/v) of test material in acetone/PEG400 and applied to the shaved and clipped flanks. The patches were left on for 24 hours and assessments carried out approximately 24 and 48 hours after the patches were removed. The study was repeated using an additional four male guinea pigs weighing between 501-608 g to find a suitably irritant concentration for induction application.

MAIN STUDY
Ten guinea pigs (five male and five female) weighing between 318-347 g were randomly selected for the test group and five guinea pigs (males) were selected to be weight matched controls for challenge. All guinea pigs were examined daily and weighed weekly as an indication of general health.

A. INDUCTION EXPOSURE
- No. of exposures: 2
On day 1, at the intradermal induction test animals were treated with 0.25 % test material. Eight days later, the test and control animals were treated with 10.0 % (w/w) sodium dodecyl sulphate in petrolatum by open application over the induction injection sites. Twenty four hours later the test animals were treated with 50.0 % test material by induction application.


B. CHALLENGE EXPOSURE
- No. of exposures: 1
Eleven days after the induction application the test animals and control animals were challenged with 50.0% test material by occluded patch.

Challenge controls:

5 males

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no effects

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no effects.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no effects

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no effects.

Any other information on results incl. tables

There was no evidence of toxicity of the test substance. Daily examination showed all guinea pigs to be in good health and no significant differences in body weights were observed between the test and control guinea pigs.

As a result of the preliminary irritation tests 0.25 % was selected from the preliminary irritation test to be the highest suitably irritant concentration for the intradermal injection induction. It was not possible to establish a sufficiently irritant concentration of the test material for induction application from the preliminary work, therefore the animals were treated on day 8 of the study with 10.0 % sodium dodecyl sulphate in petrolatum by open application over the induction injection sites, followed twenty four hours later by an induction application patch of 50.0 %. 50.0 % was selected as it was the highest non-irritant concentration for the challenge patch.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

There was no evidence of sensitization reactions in any of the ten test guinea pigs challenged with 50.0 % azelaic acid at challenge. The control animals showed no response to the test material. Under the conditions of this study azelaic acid is a non sensitizer.