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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Remarks:
Freud's Complete Adjuvant Test
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Sensitizing potential of 14 mono (meth) acrylates in the guinea pig
Author:
H. B. Van Der Walle, G. Klecak, H. Geleick, T. Bensink
Year:
1982
Bibliographic source:
Contact Dermatitis Vol. 8:223-235

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Principles of method if other than guideline:
Albino female guinea pigs (350-450 g) of the Dunkin Hartley outbred strain (Olac Ltd. Bicester England). Guinea pigs were housed in pairs and fed a pellet diet supplemented with water containing vitamin C ad libitum.

Skin irritation was assessed by a single open application of 0.025 mL to a 2 cm2 area of the clipped flank of 8 animals. A mixture of 2 parts Methyl Ethyl Ketone and one part peanut oil by volume was used as a solvent. Skin reactions were read after 24 and 48 hours and reported as maximum non-irritating concentration (m.n.i.c).

Induction- On days 0, 2, 4, 7, and 9 intradermal injections with 0.1 mL of test substance emulsified in FCA were given in the shoulder area.

Challenge- Animals were challenged epicutaneously onto the shaven right flank at day 21 and shaven left flank on day 35. N-hexyl acrylate was solubilized inFCA and 0.025 mL was applied to a 2 cm2 area.

Concentrations: Induction- 0.5 M of n-hexyl acrylate in FCA; Challenge- maximum non-irritating concentration, 1M
GLP compliance:
not specified
Type of study:
Freund's complete adjuvant test
Justification for non-LLNA method:
Study conducted prior to development of LLNA method.

Test material

Constituent 1
Chemical structure
Reference substance name:
Hexyl acrylate
EC Number:
219-698-5
EC Name:
Hexyl acrylate
Cas Number:
2499-95-8
Molecular formula:
C9H16O2
IUPAC Name:
hexyl prop-2-enoate
Test material form:
liquid
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Polysciene Inc.
- Expiration date of the lot/batch: not specified

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Institute for Biomedical Research Fullinsdorf Switzerland
- Females (if applicable) nulliparous and non-pregnant: not specified
- Microbiological status of animals, when known: not specified
- Age at study initiation: not specified
- Weight at study initiation: 350 - 450 g
- Housing: pair housed
- Diet (e.g. ad libitum): Pellet diet
- Water (e.g. ad libitum): water supplmented with vitamin C
- Acclimation period: not specified

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal
Vehicle:
arachis oil
Concentration / amount:
Concentration: 0.5 M (8.6%); Amount: 0.1 mL n-hexyl acrylate in peanut oil
Day(s)/duration:
Day 0, 2, 4, 7 and 9
Adequacy of induction:
not specified
Challengeopen allclose all
No.:
#1
Route:
epicutaneous, open
Vehicle:
arachis oil
Concentration / amount:
Concentration 1.0 M/ Amount applied 0.025 mL
Day(s)/duration:
Day 21/ 24 hours duration
Adequacy of challenge:
highest non-irritant concentration
No.:
#2
Route:
epicutaneous, open
Vehicle:
arachis oil
Concentration / amount:
Concentration 1.0 M/ Amount applied 0.025 mL
Day(s)/duration:
Day 35/ 24 hours duration
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
Experimental: 8; Control: 4 - 6
Details on study design:
RANGE FINDING TESTS:
Skin irritation was assessed by a single open application of 0.025 mL to a 2 cm2 area of the clipped flank of 8 animals. A mixture of 2 parts Methyl Ethyl Ketone and one part peanut oil by volume was used as a solvent. Skin reactions were read after 24 and 48 hours and reported as maximum non-irritating concentration (m.n.i.c).

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 5
- Exposure period: Day 0, 2, 4, 7 and 9
- Test groups: 0.1 mL intradermal injections of 0.5M of n-hexyl acrylate in FCA and equal volume of distilled water
- Control group: Same treatment as test group with acrylate omitted
- Site: 4X6 cm clipped area of shoulder
- Frequency of applications: single
- Duration: not applicable for injection
- Concentrations: 0.5 M

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: Day 21 and Day 35
- Test groups: Day 21: 0.025 mL of solubilized n-hexyl acrylate in FCA onto an uncovered area of 2 cm2; Day 35: 0.025 mL of solubilized n-hexyl acrylate in FCA onto an uncovered area of 2 cm2
- Control group: Same treatment as test group with acrylate omitted
- Site: Day 21: shaved right flank; Day 35: shaved left flank
- Concentrations: 1.0 M
- Evaluation (hr after challenge): 24 and 48 hours
Positive control substance(s):
no

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
1.0 M
No. with + reactions:
8
Total no. in group:
8
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
1.0 M
No. with + reactions:
8
Total no. in group:
8
Remarks on result:
positive indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
The Freud's complete adjuvant test to assess the skin sensitization potential of n-hexyl acrylate (>99% purity) was positive. This finding warrants the classification of n-hexyl acrylate as a skin sensitizer Ctaegory 1B under the Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP).
Executive summary:

N-hexyl Acrylate (>99% purity) was examined for its potential to be a skin sensitizer using the Freud's complete adjuvant test described by Klecak and Geleick. Following a preliminary irritation test, 8 guinea pigs were treated by intradermal injection (0.5M; 8.6% (w/v) vehicle/ n-hexyl acrylate) to induce sensitization. Guinea Pigs were challenged by topical application (1.0 M; 17.2% w/v n-hexyl acrylate in peanut oil). Indications of sensitization were noted in all eight animals. This finding warrants the classification of n-hexyl acrylate as a skin sensitizer Category 1B under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP).