Sodium hydrogen L-aspartate

Endpoint summary

Description of key information

Skin:

In an in vitro skin corrosion test (reconstructed human epidermis model, RHE) according to OECD Guideline 431, a cell viability of 88.5 % after 3 min incubation and 91.77 % after 1 h incubation was determined (reference 7.3.1 -1). Thus, the test substance is not to be considered to be classified as skin corrosive.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-12-05 to 2017-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The reconstructed human epidermis model in vitro method is an accepted in vitro method to replace animal testing. The human skin RHE™ model closely mimics the biochemical and physiological properties of the upper parts of the human skin, i.e the epidermis.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: The SkinEthic™ RHE-model RHE/S/17 from Episkin/SkinEthic Laboratories, Lyon, France
- Tissue batch number: 16-RHE-130
- Date of initiation of testing: 2016-12-14

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: gently rinsing with a minimum volume of 20 mL DPBS using a pipette. Excess DPBS was removed by gently shaking the tissue inserts and blotting the bottom of the tissue inserts with blotting paper.
- Observable damage in the tissue due to washing: No
- Modifications to validated SOP: No

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg/mL
- Incubation time: 3 h ± 15 min
- Spectrophotometer: microplate reader (ELx800, BioTek Instruments GmbH, Bad Friedrichshall, Germany)
- Wavelength: 570 nm

NUMBER OF REPLICATE TISSUES: 2

PREDICTION MODEL / DECISION CRITERIA:
- The test substance is considered to be corrosive to skin if the viability after 3 minutes exposure is less than 50 %, or if the viability after 3 minutes exposure is greater than or equal to 50 % and the viability after 1 hour exposure is less than 15 %.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 20 ± 3 mg

NEGATIVE CONTROL
- Amount applied: 40 ± 3 µL

POSITIVE CONTROL
- Amount applied: 40 ± 3 µL

Duration of treatment / exposure:

3 min or 1 h

Number of replicates:

2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 min

Value:

88.5

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1 h

Value:

91.77

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: No
- Direct-MTT reduction: No
- Colour interference with MTT: No


ACCEPTANCE OF RESULTS (see any other information on results):
- Acceptance criteria met for negative control: Yes
- Acceptance criteria met for positive control: Yes
- Acceptance criteria met for variability between replicate measurements: Yes

Acceptability of the Test

Acceptability of the Negative Control: The negative control OD values were 2.019, 2.059, 1.675 and 1.699 and, thus, in the range of ≥ 0.8 and ≤ 3.0.

Acceptability of the Positive Control: After treatment with the positive control (potassium hydroxide, 8N) the mean viability value was 0.59 % after 1 hour exposure and, thus, lower than 15 %.

Test Substance Data Acceptance Criteria: The range between identically treated tissues was less than 30 % (20.74 % after 3 minutes exposure and 0.65 % after 1 hour exposure).

The study met all acceptance criteria.

The results obtained after treatment of the reconstructed human epidermis model with Art. 11195 (L-Aspartic acid sodium salt monohydrate) are given in the following table:  

		Tissue 1		Tissue 2		Mean		CV
		OD	Viability (%)	OD	Viability (%)	OD	Viability (%)	Viability (%)
Negative Control	3 min	2.019	99.02	2.059	100.98	2.039	100.00	1.39
	1 h	1.675	99.30	1.699	100.70	1.687	100.00	0.99
Positive Control	1 h	0.009	0.51	0.011	0.66	0.010	0.59	17.90
Test Substance	3 min	1.635	80.19	1.974	96.81	1.804	88.50	13.28
	1 h	1.553	92.07	1.543	91.48	1.548	91.77	0.46

Interpretation of results:

other: not corrosive (GHS Cat. 1)

Conclusions:

In an in vitro skin corrosion test (reconstructed human epidermis model, RHE) according to OECD Guideline 431, a cell viability of 88.5 % after 3 min incubation and 91.77 % after 1 h incubation was determined. According to the evaluation criteria, the test substance did not show skin corrosive properties.

Executive summary:

In an in vitro skin corrosion test (reconstructed human epidermis model, RHE) according to OECD Guideline 431, 20 mg L-Aspartic acid sodium salt monohydrate was applied topically to a human reconstructed skin model followed by determination of the cell viability. Cell viability was determined by enzymatic conversion of vital dye MTT into a blue formazan salt and measurement of the formazan salt after extraction from tissues. No direct MTT-reducing properties of the test substance were observed. Duplicates of the human skin RHE-model were treated with the test substance or the negative control for 3 minutes and additional 1 hour. Duplicates with the positive control were only treated for 1 hour. 40 µL of either the negative control (deionised water) or the positive control (potassium hydroxide, 8N) were applied to the tissues. Results of the positive and negative control were valid. After treatment with the test substance, a mean cell viability of 88.50 % (3 min incubation) or 91.77 % (1 h incubation) was determined.

Under the test conditions, the test substance is not considered to possess a corrosive potential to skin. Furthermore, it was assumed, that the anhydrate form has the same corrosive potential to the skin and thus the result of the test item is also applicable.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin:

In an in vitro skin corrosion test (reconstructed human epidermis model, RHE) according to OECD Guideline 431 (reference 7.3.1 -1), 20 mg L-Aspartic acid sodium salt monohydrate was applied topically to a human reconstructed skin model followed by determination of the cell viability. Cell viability was determined by enzymatic conversion of vital dye MTT into a blue formazan salt and measurement of the formazan salt after extraction from tissues. No direct MTT-reducing properties of the test substance were observed. Duplicates of the human skin RHE-model were treated with the test substance or the negative control for 3 minutes and additional 1 hour. Duplicates with the positive control were only treated for 1 hour. 40 µL of either the negative control (deionised water) or the positive control (potassium hydroxide, 8N) were applied to the tissues. Results of the positive and negative control were valid. After treatment with the test substance, a mean cell viability of 88.50 % (3 min incubation) or 91.77 % (1 h incubation) was determined.

Under the test conditions, the test substance is not considered to possess a corrosive potential to skin. Furthermore, it was assumed, that the anhydrate form has the same corrosive potential to the skin and thus the result of the test item is also applicable.

The present study is required for a registration under another legislation, no further testing is necessary (e.g. skin irritation). Under REACH, the test substance is considered to be registrated using the Annex III exemption. Therefore, no studies on the skin or eye irritating properties of the test substance were conducted. However, all available information on health effects of the test substance were included in this REACH-registration dossier.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008.

As a result the substance is not considered to be classified for skin corrosion under Regulation (EC) No 1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.