4-acetyl-2-methylbenzoic acid

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 March 2018 – 01 May 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Version / remarks:

2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-acetyl-2-methylbenzoic acid

EC Number:

856-079-4

Cas Number:

55860-35-0

Molecular formula:

C10H10O3

IUPAC Name:

4-acetyl-2-methylbenzoic acid

Test material form:

solid: particulate/powder

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Details on animal used as source of test system:

Not applicable

Justification for test system used:

The purpose of this test is to evaluate the corrosivity potential of the test item using the EpiDerm™ Human Skin Model after treatment periods of 3 and 60 minutes.
Corrosion is directly related to cytotoxicity in the EpiDerm™ tissue. Cytotoxicity is determined by the reduction of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to formazan by viable cells in the test item treated tissues relative to the corresponding negative control. The results are used to predict the corrosivity potential of the test item.
This model incorporates several features, which make it advantageous in the study of potential dermal corrosivity. The target cells are epithelial, derived from human skin, and formed into a stratified, cornified epithelium. Test items are applied to the culture surface, at the air interface, so that undiluted and/or end use dilutions can be tested directly.

Vehicle:

water

Remarks:

sterile, distilled

Details on test system:

Supplier: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia
Date received: 24 April 2018
EpiDerm Tissues (0.63cm2) lot number: 25899
Assay Medium lot number: 041918TMB

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

Amount/concentration applied:

50 µL of sterile distilled water (negative control) was applied to tissues, 25mg of test substance was applied and wetted with 25 µL of sterile water, 50 µL of 8.0 N potassium hydroxide (positive control)

Duration of treatment / exposure:

3 and 60 minutes

Duration of post-treatment incubation (if applicable):

MTT loading: incubation for 3 hours
MTT extraction (isopropanol): overnight

Number of replicates:

Duplicate tissues were used for each treatment group.

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

60-minute exposure

Value:

99.5

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3-minute exposure

Value:

104

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Other effects / acceptance of results:

The quality criteria required for acceptance of results in the test were satisfied. The mean OD570 for the tissues treated with the vehicle was 1.831 for the 3-minute exposure period and 1.976 for the 60-minute exposure period, which is within the acceptable range defined in the test guideline. The relative mean tissue viability for the positive control tissues was 2.4% relative to the negative control following the 60-minute exposure period. The positive control acceptance criterion was therefore satisfied. The coefficient of variation between the two tissue replicates of each treatment group did not exceed 30%, and the acceptance criterion was satisfied.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The substance was considered to be non-corrosive to the skin in this in vitro assay.

Executive summary:

The skin corrosivity potential of the test substance was evaluated under GLP to OECD TG 431 using the EpiDerm Human Skin Model. Corrosion is directly related to cytotoxicity in the EpiDerm tissue. Cytotoxicity is determined by the reduction of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to formazan by viable cells in the test item treated tissues relative to the corresponding negative control. The results are used to make a prediction of the corrosivity potential of the test item.
Duplicate tissues were treated with the test substance for exposure periods of 3 and 60 minutes. Negative control (sterile, distilled water) and positive control (8.0 N potassium hydroxide) groups were treated for each exposure period. At the end of the exposure period the test or control substance was rinsed from each tissue before each tissue was taken for MTT loading. After MTT loading each tissue was placed in 2 mL isopropanol for MTT extraction. At the end of the formazan extraction period each well was mixed thoroughly and three aliquots of 200 µL were transferred to the appropriate wells of a pre-labelled 96 well plate. The optical density (OD) was measured at 570 nm (OD570). The cell viability of the tissues treated with the positive control substance potassium hydroxide was 2.9% after the 3-minute exposure period and 2.4% after the 60-minute exposure period in relation to the viability of the tissues treated with the vehicle control. The respective cell viability of the tissues treated with the test substance was 104.0% after the 3-minute exposure period and 99.5% after the 60-minute exposure period. The substance was considered to be non-corrosive to the skin under the conditions of the test.