Sodium hydrogen m-sulphonatobenzoate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

Adopted on 28 July 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium hydrogen m-sulphonatobenzoate

EC Number:

241-602-5

EC Name:

Sodium hydrogen m-sulphonatobenzoate

Cas Number:

17625-03-5

Molecular formula:

C7H6O5S.Na

IUPAC Name:

sodium 3-sulfobenzoate

Test material form:

solid: particulate/powder

Details on test material:

White crystalline powder.

Specific details on test material used for the study:

Identity Sodium 3-sulfobenzoate
Alternative names 3-Sulpho Benzoic AcidMono Sodium Salt
SBA (3-Sodiosulfobenzoic Acid)
Sodium hydrogen m-sulphonatobenzoate
Label name 3-Sodiosulfobenzoic Acid
Batch no. 170103
Retest date 14 February 2019
Storage conditions Room temperature
RTC number 15432

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Details on test system:

The test system EPISKINTM is commercially available from SkinEthic Laboratories.

Characteristic of the test system
The SkinEthic reconstructed human tissue model EPISKINTM consists of an airlifted, living, multi-layered tissue construct, produced in polycarbonate inserts in serum-free and chemically defined medium, featuring normal ultra-structure and functionality equivalent to human tissue in vivo.
Normal human keratinocytes are used to reconstruct the epithelium. Multiple layers of viable epithelial cells (basal layer, stratum spinosum, stratum granulosum) should be present under a functional stratum corneum. Stratum corneum should be multilayered containing the essential lipid profile to produce a functional barrier with robustness to resist rapid penetration of cytotoxic marker chemicals.

Functional conditions
The barrier function should be demonstrated. The containment properties of the RhE model should prevent the passage of material around the stratum corneum to the viable tissue, which would lead to poor modelling of skin exposure. The RhE model supplier should ensure that each batch of the RhE model used meets defined production release criteria. A certificate will be supplied for each batch of the test system.

Preparation and storage of the test system
Immediately after arrival, the plate will be opened under a sterile airflow and the sterile filter paper removed. Each insert containing the epidermal tissue will be carefully taken out. Any remaining agarose that adheres to the outer sides of the insert will be rapidly removed by gentle blotting on the sterile filter paper. Inserts will be quickly placed in a 12-well plate (supplied) in which each well has previously been filled with 2 mL/well SkinEthic. Maintenance Medium (at room temperature) making sure that no air bubbles are formed underneath the inserts.
Culture dishes will be placed in the incubator at 37°C, 5% CO2 and saturated humidity. Testing can initiate after at least two hours of incubation.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

In the Main Assay, alive tissues were treated with the test item, positive and negative controls. The treatment scheme was the following:
Negative control (D-PBS) amount per well 20 µL (3 replicates)
Positive control (5% (w/v) SDS) amount per well 20 µL (3 replicates)
Test Item (sodium 3-sulfobenzoate) amount per well 20 mg (3 replicates).

Duration of treatment / exposure:

Exposure period
An exposure time of 15±0.5 minutes was allowed in a ventilated cabinet at room temperature.

Washing
At the end of the exposure, each tissue was rinsed with approximately 25mL of sterile D-PBS, filling and empting the tissue insert. The excess liquid was carefully removed and the sample transferred in new wells pre-filled with 2mL/well of maintenance medium.

Duration of post-treatment incubation (if applicable):

Post-exposure period
A 42 ± 1 hour recovery period was allowed by incubation at 37°C, 5% CO2 and saturated humidity.

Number of replicates:

3

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

experiment 1 (A1)

Value:

93.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

110.4 % tissue viability

Positive controls validity:

valid

Remarks:

3.1 % tissue viability

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

experiment 2 (A2)

Value:

118

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

89.8 % tissue viability

Positive controls validity:

valid

Remarks:

4.6 % tissue viability

Results 3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

experiment 3 (A3)

Value:

96.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

99.8 % tissue viability

Positive controls validity:

valid

Remarks:

4.5 % tissue viability

Results 4

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Mean

Value:

102

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

100 % tissue viability (mean)

Positive controls validity:

valid

Remarks:

4 % tissue viability (mean)

Any other information on results incl. tables

Preliminary test

Before the Main Assay, a preliminary test was carried out to evaluate the compatibility of the test item with the test system. In a first step, the test item was assayed for the ability of reducing MTT per se. An opaque yellow colour was noted in the MTT solution at the end of the incubation period. This no relevant colour change indicated that the test item could not direct interact with MTT.

In a second step, the test item was assayed for the ability of colouring water per se. A colourless solution was observed, indicating that the test item has no potential interfering ability.

Based on the results obtained, no additional control was added in the Main Assay.

Main Assay

A Main Assay was performed. The mean Optical Density of Blank Controls was 0.038, lower than the maximum acceptable value (0.1). The negative control gave the expected baseline value (Optical Density values of the three replicates higher than 0.6) and variability (Standard Deviation of the % viability lower or equal to 18), in agreement with guideline indications. According to the method, the mean value is considered the baseline value of the experiment and thus represents 100% of cell viability.

Positive control results indicated an appropriate cell death with an acceptable relative cell viability (4% of the negative control value). Variability between replicates gave also the expected value (SD of % viability = 0.8). Based on the stated criteria, mean viability, expressed as percentage of the negative control, lower or equal to 40% and standard deviation of % viability equal or lower than 18, the study was accepted as valid.

The test item did not induce cell death in any replicate, the mean cell viability after the blank subtraction was 102%, when compared to the negative control. Acceptable intra-replicate variability was obtained (SD of % viability = 13.5 lower than 18).

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The blank, negative and positive controls gave acceptable results and the study was accepted as valid. The mean cell viability of the test item treated tissues, after the blank subtraction, was 102%. Based on the results obtained, the test item Sodium 3-sulfobenzoate is classified as non-irritant to the skin (UN GHS No Category).

Executive summary:

The potential of the test item Sodium 3-sulfobenzoate to be irritant to the skin was investigated through an in vitro skin irritation study (according to OECD Guideline 439), using a commercial reconstructed human epidermis (RhE) model named EPISKIN™.

The blank, negative and positive controls gave acceptable results and the study was accepted as valid. The mean cell viability of the test item treated tissues, after the blank subtraction, was 102%. Based on the results obtained, the test item Sodium 3-sulfobenzoate is classified as non-irritant to the skin (UN GHS No Category).