9-Octadecenedioic acid

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

19 Jun - 12 Jul 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions. The epicutaneous induction and challenge were performed under semi-occlusive conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted Jul 1992

Deviations:

yes

Remarks:

epicutaneous induction and challenge performed under semi-occlusive conditions

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

yes

Remarks:

epicutaneous induction and challenge performed under semi-occlusive conditions

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

(Z)-9-Octadecene-1,18-dioic acid

Cas Number:

20701-68-2

Molecular formula:

C18H32O4

IUPAC Name:

(Z)-9-Octadecene-1,18-dioic acid

Constituent 2

Reference substance name:

(Z)-9-Octadecen-1,18-dioic acid

IUPAC Name:

(Z)-9-Octadecen-1,18-dioic acid

Details on test material:

- Name of test material (as cited in study report): C18:1 dicarboxylic acid
- Physical state: dark yellow solid
- Analytical purity: ca. 90%
- Lot/batch No.: L93046
- Expiration date of the lot/batch: 1 Jan 1997
- Storage condition of test material: at room temperature in the dark

In vivo test system

Test animals

Species:

guinea pig

Strain:

Himalayan

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: BRL Ltd., Basel, Switzerland
- Age at study initiation: approximately 5 weeks
- Weight at study initiation: 361 - 403 g
- Housing: 5 animals per cage in metal cages with wire mesh floor
- Diet: LC 23-B pelleted guinea pig diet including ascorbic acid (Hope Farms, Woerden, the Netherlands), ad libitum and hay (B.M.I. Helmond, the Netherlands) once per week
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 50
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

other: intradermal and epicutaneous, semi-occlusive

Vehicle:

propylene glycol

Induction 2

Concentration / amount:

Induction: 50% (intradermal) and 10% (epicutaneous)
Challenge: 5%

Challenge

Challenge 1

Route:

epicutaneous, semiocclusive

Vehicle:

propylene glycol

Challenge 2

Concentration / amount:

Induction: 50% (intradermal) and 10% (epicutaneous)
Challenge: 5%

No. of animals per dose:

10 (treatment group)
5 (control group)

Details on study design:

RANGE FINDING TESTS:
Prior to the start of the main study, the intradermal and epidermal irritancy of the test substance was investigated to select suitable concentrations for the induction and challenge phase of the main study. The selection was based on the absence of toxicity and on the following criteria for each route and/or study phase:
Induction (intradermal and epidermal): The highest possible concentration that produced moderate irritation (the intradermal reactions may include slight necrosis (< 3 mm in diameter)).
Challenge: The maximum non-irritant concentration.

A series of test substance concentrations were tested. The first and subsequent concentrations were selected from the series: 50%, 20%, 10%, 5%, 2%, 1% and if needed, further lower concentrations using the same steps. The test system and procedures were identical to those used during the main study, unless otherwise specified. The three animals were 5-9 weeks old. The body weights were determined prior to treatment (results not shown).

Intradermal injections:
A series of four test substance concentrations was used; the highest concentration was the maximum concentration that could technically be injected (undiluted). Each of the three animals received two different concentrations in duplicate (0.1 mL/site) in the clipped scapular region. The injection sites were assessed for irritation 24 and 48 hours after treatment. Necrosis observed at all injection sites was considered to be caused by propylene glycol. A 50% solution for the intradermal injection and a 10% solution for the epidermal induction was selected for the in the main study.

Epidermal application:
A series of four test substance concentrations (10, 20, 50 and 100%) was used. All concentrations could technically be applied. Two different concentrations were applied (0.5 mL each) per animal to the clipped flank, using Scatchpak-non-woven patches (2x3 cm) mounted on Micropore tape, which were held in place with Coban elastic bandage (semi-occlusive covering). The animals receiving intradermal injections were treated with the lowest concentrations (5 and 10%) and two further animals with the highest concentrations (20 and 50%). After 24 h, the dressing was removed and the skin cleaned of residual test substance. The treated skin areas were assessed for irritation 24 and 48 h after exposure. Severe erythema with necrosis and slight edema was noted at the sites treated with 50% and 20% solutions. Very slight erythema was observed at the sites treated with 10% and non skin reactions were noted at sites treated with a 5% solution. The 5% solution was selected for the challenge phase in the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2, intradermal and epicutaneous
- Exposure period: single injection (epidermal) and 48 h (epicutaneous)
- Test groups:
Intradermal, Day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) Freunds Complete Adjuvant (FCA)/water for injection
Injection 2: 50% test substance
Injection 3: separate injections of 0.05 mL each of 50% test substance and FCA (a 1:1 mixture of test substance and FCA was technically not possible; the mixture was divided in separate layers after preparation and cound not be used for injection).
48 h after intradermal injection (Day 3), the degree of erythema and edema was evaluated.

Epicutaneous, Day 8:
0.5 mL 10% test substance was applied to a clipped skin area. The semi-occlusive dressing was kept in place for 48 h. The degree of erythema and edema was evaluated directly after cleaning the skin area with water (Day 10).

- Control group:
Intradermal, day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) FCA/water
Injection 2: propylene glycol
Injection 3: propylene glycol (w/v) in a 1:1 mixture (w/w) FCA (final concentration is 50% propylene glycol)

Epicutaneous, Day 8: 0.5 mL propylene glycol

- Site: the shoulder region
- Frequency of applications: once (intradermal on Day 1 and epicutaneous on Day 8)
- Duration: Day 1 (intradermal), Day 8-10 (epicutaneous)
- Concentrations: undiluted (intradermal and epicutaneous)

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: 21
- Exposure period: 24 h
- Test groups: 0.5 mL test substance
- Control group: 0.5 mL test substance
- Site: approximately 20 mm x 30 mm, on one flank of the animals
- Concentration: 5%
- Evaluation (hr after challenge): 24 and 48 h after the challenge ended

Positive control substance(s):

yes

Remarks:

alpha-hexylcinnamicaldehyde, tech. 85%

Results and discussion

Positive control results:

A reliability check was carried out at regular intervals with alpha-hexylcinnamic aldehyde to check the sensitivity of the test system and the reliability of the experimental methods used by the test laboratory. In an independent study performed in May 1996 (report No. 175038), alpha-hexylcinnamic aldehyde induced sensitisation in 100% (10/10) of the Himalayan guinea pigs challenged with a 50% solution. A 5% solution was used for intradermal induction and undiluted test substance was used for topical induction.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

5%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 5.0.

Results 2

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Results 3

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

5%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 5.0.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Any other information on results incl. tables

48 h after intradermal induction, very slight to well-defined erythema was noted at all of the sites injected with FCA/water in 10/10 treated and 5/5 control animals. Necrosis was observed at all the water/test substance and FCA/test substance injection sites in 10/10 treated and 5/5 control animals. The authors concluded that the vehicle, propylene glycol, caused the irritation as the same effects were noted in the preliminary study. Following epidermal induction, very slight erythema was observed in 2/10 treated animals. 24 and 48 h after the challenge ended, no sensitisation reactions were observed in the treated animals. No skin irritation was noted in any of the treated and control animals. There was no mortality during the study period, and no signs of toxicity or treatment-related effects on body weight were observed.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

CLP: not classified