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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
year of publication: 1986
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
sufficiently documented literature data with some shortcomings (results were not presented for each animal) (reliable with restrictions), but as MEST is suitable as a screening test only and cannot be used to cover the endpoint as a stand-alone test, RL3 is assigned to this study
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1986
Report date:
1986

Materials and methods

Principles of method if other than guideline:
Mouse Ear Swelling Test (MEST) (mentioned as method in OECD TG 406 (adopted 17.07.1992) on skin sensitisation, but according to this testing guideline negative results obtained in MEST, have to be verified with guinea pig assays)
GLP compliance:
not specified
Type of study:
mouse ear swelling test
Justification for non-LLNA method:
The study was performed before 11th october 2016 when LLNA test was not requested as default. When used in a weight of evidence approach the data are considered to fulfill data requirements for skin sensitisation. Further details are given in the endpoint summary.

Test material

Constituent 1
Chemical structure
Reference substance name:
N-butyl acetate
EC Number:
204-658-1
EC Name:
N-butyl acetate
Cas Number:
123-86-4
Molecular formula:
C6H12O2
IUPAC Name:
butyl acetate
Details on test material:
- Name of test material (as cited in study report): butyl acetate
- purity: at least 98%

In vivo test system

Test animals

Species:
mouse
Strain:
CF-1
Sex:
female
Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: 6-8 weeks
- Housing: five per cage in wire-bottom stainless-steel cages
- Diet: Purina Rodent Laboratory Chow 5001 ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, open
Vehicle:
other: 70% ethanol
Concentration / amount:
100% induction
50% challenge
Challengeopen allclose all
Route:
epicutaneous, open
Vehicle:
other: 70% ethanol
Concentration / amount:
100% induction
50% challenge
No. of animals per dose:
10 or 15 animals per test group, 5 or 10 animals in the control group (not clearly specified)
Details on study design:
RANGE FINDING TESTS:
- four groups with 2 mice each
- four induction applications over a 4-day period and mock "challanged" once on the ears (each group at a different concentration)
- concentrations used in the main study were the highest which were minimally or nonirritating to the stomach region (for induction) and nonirritating to the ear (for challenge)

MAIN STUDY:
- animals were shaved and tape stripped at the start of the study (stomach region)
- two intradermal injections of FCA (Freund's Complete Adjuvans) were performed into the stomach induction site prior to the first induction application
- induction was performed with 100 µl of test item
- tape stripping and topical application were repeated for three additional consecutive days

CHALLENGE
- challenge was performed 7 days after the last application for induction: 20 µl of a 50% dilution of the test item in 70% ethanol were applied to the left ear and 20 µl of the vehicle (when necessary) to the right ear
- 24 and 48 hours after this challenge thicknesses of both ears were measured under light ether anesthesia

- ears were measured using a spring-loaded "Oditest" D1000 gauge

EVALUATION
- positive response (based on an animal-by-animal basis): test ear showed at least a 20% greater thickness than the control ear
- percentage responsiveness was calculated

Positive control substance(s):
yes
Remarks:
e.g. N,N-dimethyl-p-nitrosoaniline and 1-chloro-2,4-dinitrobenzene (DNCB), for further information see below

Results and discussion

Positive control results:
N,N-dimethyl-p-nitrosoaniline: 100% of tested animals were sensitised (0.3% induction concentration; 0.3% challenge concentration in 70% ethanol)
DNCB: 80% of tested animals were sensitised (0.5% induction concentration; 1% challenge concentration in 70% ethanol)

In vivo (non-LLNA)

Results
Reading:
other: 1st and 2nd reading
Group:
test chemical
Dose level:
20 µl of 50% solution
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no data
Remarks on result:
other: Reading: other: 1st and 2nd reading. Group: test group. Dose level: 20 µl of 50% solution. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no data.

Any other information on results incl. tables

0% of the test animals (10 or 15, not clearly stated) were sensitized by butyl acetate

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: expert judgment
Conclusions:
n-Butyl acetate was not sensitising in the mouse ear swelling test.
Executive summary:

A mouse ear swelling test (MEST) was performed with n-butyl acetate in female CF-1 mice (at least 10 animals in the test group and 5 animals in the control group). Induction was performed with the pure test substance and challenge with a 50% dilution in 70% ethanol. The test item was not sensitising in this test (Gad et al., 1986).

The study was judged to be not reliable (RL3), as the MEST is a screening study only and cannot be used as a stand-alone study to cover this endpoint. Negative results obtained with the MEST should be confirmed by a guinea pig test. So, a MEST alone does not fulfil the information requirement. The study is used in a "weight of evidence" approach.