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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
(R)-thiazolidine-4-carboxylic acid
EC Number:
EC Name:
(R)-thiazolidine-4-carboxylic acid
Cas Number:
Molecular formula:
(R)-thiazolidine-4-carboxylic acid
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
Batch no. 20190104
Retest date January 2021
Storage conditions Room temperature

In vitro test system

Test system:
human skin model

Test system

yes, concurrent positive control
yes, concurrent negative control
Duration of treatment / exposure:
15 minutes
Observation period:
42 +/- 1 hour recovery period
Details on study design:
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. Light purple solution was noted in the MTT solution at the end of the
incubation period, indicating that the test item could direct interact with MTT. In a second
step, the test item was assayed for the ability of colouring water per se. A white opaque
suspension was observed. This suspension was not dispensable with automatic pipettes,
thus spectrophotometric analysis was not performed. Based on these results, additional
controls were added in the Main Assay.
In the Main Assay, the test item was applied as supplied in three replicates at the treatment
level of 20±2mg/epidermis unit, each measuring 0.38 cm2 (treatment level: 53 µL/cm2).
Positive and negative controls [a 5% (w/v) sodium dodecyl sulphate solution in water and
Dulbecco’s phosphate buffered saline (D-PBS), respectively] were concurrently tested, in
the same number of replicates and test conditions at the treatment level of 20 µL/epidermis
unit. In order to verify if the test item results had to be corrected, the non specific colour
(NSCliving) was evaluated using two alive treated tissues without MTT staining and compared
with the D-PBS control. Moreover, non specific MTT reduction (NSMTT) was evaluated
using two killed tissues and compared with negative control performed with alive tissues.
Since the test item is able both to stain tissue and reduce MTT, to avoid a possible double
correction for colour interference, a third control for Non Specific Colour in killed tissue
(NSCkilled) was performed.

Results and discussion

In vitro

Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Other effects / acceptance of results:
In the Main Assay, the negative control gave the expected baseline value (Optical Density
values of the three replicates higher than 0.6) and variability [Standard Deviation (SD) of
% viability lower or equal to 18], in agreement with the guideline indications. According
to the method, the negative control mean value is considered the baseline value of the
experiment and thus represents 100% of cell viability.
The positive control caused the expected cell death (7% of cell viability when compared to
the negative control) and variability (SD of % viability equal to 2.05). Based on the stated
criteria (mean viability ≤ 40% and SD of % viability ≤ 18), the assay was regarded as valid.
Both NSCliving and NSMTT values were lower than 5%, therefore only the blank subtraction
was performed.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
The test item did not induce cell death in any replicate, the mean cell viability after the blank
subtraction was 84% when compared to the negative control. Intra-replicate variability
was acceptable with a SD of % viability value equal to 3.62 (lower than 18, as stated in the
Study Protocol).
Based on the results obtained, the test item L(-)-Thiazolidine-4-carboxylic acid (TCA) is
classified as non-irritant to the skin (UN GHS No Category).