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EC number: 200-745-3 | CAS number: 71-00-1
L-histidine is not irritating to the skin or the eyes.
In the current study the skin irritation potential of the test item L-HISTIDINE was assessed in an in vitro membrane barrier assay, using a commercial reconstructed human epidermis (RhE) model named EPISKINTM . The study was according to OECD 439 and GLP.
In a first step, the test item was assayed for the ability to reduce MTT. At the end of the incubation period, a yellow/grey solution, without precipitate, was observed, indicating that the test item could directly interact with MTT. Thus, additional controls were added in the Main Assay for the evaluation of MTT non specific reduction (NSMTT).
In a second step, the test item was assayed for the ability to colour water. A colourless suspension, with plenty white precipitate, was observed, which indicates that the test item does not have a colouring ability. For this reason, no additional controls were added in the Main Assay for the evaluation of non specific colouring potential (NSC).
Using alive tissues, the negative control gave the expected baseline value and variability, in agreement with guideline indications. According to the method, the mean negative control value is considered the baseline value of the experiment and thus represents 100% of cell viability.
The positive control showed cell death with an acceptable relative cell viability of 6.2 % in function of the negative control. Variability between replicates was acceptable (SD of % viability = 4.3). Based on the criteria the study was accepted as valid.
The test item did not induce any relevant reduction of MTT staning in any replicate. The mean cell viability was 106.9% in function of the negative control. The variability between the replicates was 18.8, which is slightly higher than the stated in the Study Acceptability Criteria, however, the study was considered valid since the Optical Density value of each test item replicate sample was comparable to the negative control values.
The classification criteria in the CLP legislation are not directly applicable to an in vitro test. Therefore, as described in OECD 439 the following cut-off time values are used.
mean relative viability =< 50%: irritant (GHS Category 2)
mean relative viability > 50%: not irritant (GHS No category)
Based on these results L-Histidine should be considered as not irritant to the skin.
Optical density at 492 nm of Blank:
cMEM without phenol red
Measured value- blank
Mean of replicate
Mean of 3 replicates
The potential of L-HISTIDINE to cause eye irritation or eye dammage was assessed with the in vitro BCOP assay. The study was performed according to OECD 437 and GLP.
The positive and negative control results met the criteria, indicating that the test system was valid.
The IVIS score for the test item was calculated to be 0.32. As this is below the threshold value of 3, L-histidine was found to not induce effects to the eye.
In a first study the skin corrosion potential of the test item L-HISTIDINE was assessed with the in vitro membrane barrier assay CORROSITEX® . The study was according to OECD 435 and GLP.
The test item did not not have the ability to penetrate the biobarrier.
In the second study the skin irritation potential of the test item L-HISTIDINE was assessed in the in vitro membrane barrier assay EPISKINTM. The study was according to OECD 439 and GLP.
Both the negative and positive controls gave results in agreement with guideline indications and based on the criteria the study was accepted as valid. The test item did not induce any reduction in cell viability.
The test item was found to not induce effects to the eye.
As the vitro studies are sufficient to conclude upon the classification and labelling for L-HISTIDINE with regard to both irritation to the skin and to the eyse, in vivo skin irritation/corrosion and in vivo eye dammage tests were not performed. This is in line with the REACh regulation as no additional animal testing was conducted when deemed unnecessary.
The classification criteria in the CLP legislation are not directly applicable to the in vitro tests. Therefore, the cut off values described in the relevant OECD guidelines are used for the classification of the substance.
For the first study the following cut-off time values are:
Category GHS 1A: 0-3 minutes
Category GHS 1B: >3-30 minutes
Category GHS 1C: >30-60 minutes
Non-corrosive >60 minutes.
L-Histidine did not penetrate the barrier for 65 minutes, therefore it should be considered as non corrosive to the skin.
For the second study the following cut-off time values are:
The mean relative viability of L-Histidine was 106.9%, therefore, it should be considered as not irritant to the skin.
The BCOP study allows to conlude on the classification of a substance if the IVIS is found to be <= 3 (no classification), or >= 55 (eye damage Cat. 1).
For L-HISTIDINE the IVIS score was found to be 0.32, thus allowing to conclude that the substance is not corrosive or irritant to the eyes.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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