Registration Dossier

Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well documented study according to international accepted guidelines and GLP compliant.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
Test item: 4-aminobutyric acid
CAS No. 56-12-2
Batch No. 0019D35 (10600120141102)
Physical state: solid substance, crystalline powder
Storage at: 15-30 °C

Test system

Details on study design:
Human Skin Model:
EpiSkinTM Small Model (EpiSkinTMSM), manufactured by EPISKIN SNC Lyon, France, is a three-dimensional human epidermis model. Adult human-derived epidermal keratinocytes are seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after 13-day culture period comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum (Tinois et al., 1994). Its use for skin irritation testing involves topical application of test materials to the surface of the epidermis, and the subsequent assessment of their effects on cell viability.
Justification for selection of the test system: The EPISKIN model has been validated for irritation testing in an international trial.

Results and discussion

In vivo

Irritant / corrosive response data:
Disks of EPISKIN (three units / chemical) were treated with test item and incubated for 15 minutes at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. Epidermis units were then incubated at 37 °C for 42 hours in an incubator with 5% CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37°C in 5% CO2 protected from light. The precipitated formazan was then extracted using acidified isopropanol and quantified spectrophotometrically.
SDS (5% aq.) and PBS treated epidermis were used as positive and negative controls respectively. For each treated tissue viability was expressed as a percentage relative to negative control.
The test item is considered to be irritant to skin, if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less or equal (≤) to 50% of the negative control.
In this in vitro skin irritation test using the EPISKIN model, the test item reduced cell viability in comparison to the negative control (mean value: 69 %). However, all obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control, therefore the test item was considered to be non-irritant to skin.
Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid.

Any other information on results incl. tables

Substance

OpticalDensity(OD)

Viability(%)

NegativeControl:

1 x PBS

mean

0,799

100

standarddeviation(SD)

6,85

PositiveControl:

SDS (5%aq.)

mean

0,062

8

standarddeviation(SD)

3,43

TestItem:

4 -aminobutyric acid

mean

0,554

69

standarddeviation(SD)

2,19

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: OECD GHS
Conclusions:
The results obtained from this in vitro skin irritation test, using the EPISKIN model, indicated that the test item reveals no skin irritation potential under the utilised testing conditions. The test item 4-AMINOBUTYRIC ACID (CAS No. 56-12-2) is considered to be non-irritant to skin and is therefore not classified (UN GHS No Category).