Reaction mass of glycyl-L-glutamine and potassium chloride

Endpoint summary

Additional information

Justification for selection of genetic toxicity endpoint
Potassium chloride:
Bacterial tests:
In a Salmonella test (using the TA100, TA 1535, TA 1537 and TA 98 strains) doses of KCl between 0 and 10.000 µg/plate were tested with and without metabolic activation. No significant increases in mutation frequencies were noted (Mortelmans1986)
Lymphoma cell mutation assays:
Two independent laboratories performed the Mouse Lymphoma Mutation Tests on a range of substances including KCl. Myhr 1988: A Mouse Lymphoma assay was performed according to OECD TG 476 with KCl in the presence and in the absence of a metabolic activation system.With metabolic activation KCl yielded positive results at 4000 and 5000 µg/ml; without activation it was negative up to 5000 µg/ml. However higher concentrations appeared to be toxic and mutagenic Mitchell 1988: The L5178Y mouse lymphoma cell forward mutation assay according to the respective OECD Guideline was used to determine the mutagenic activity of potassium chloride (up to 5000 µg/ml) in the presence and in the absence of a metatolic activation system.The different trials revealed different responses , but overall , potassium chloride induced weakly positive responses only in the presence of S9 -mix but not in the absence of a metabolic activation system.
According to the authors these responses indicate that high salt concentrations which affect the ionic balance and the osmotic pressure of the medium, can induce mutations in cells surviving the treatment.(Mitchell 1988, Myhr 1988).
Chromosome aberration tests:
There are reports on the effect of KCl on formation of chromosome aberrations in Chinese hamster ovary cells (CHO) and Chinese hamster Lung (V79) cells:
In a test similar or equivalent to OECD TG 476 potassium chloride induced a significant increase
in Chinese Hamster lung fibroblasts (V79) cells with chromosme aberrations only at the highest test dose (12000 µg/ml) in the absence of a metabolic activation system. Measurements of the osmotic pressure of the medium revealed a twofold i

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Potassium chloride:

Bacterial tests:

In a Salmonella test (using the TA100, TA 1535, TA 1537 and TA 98 strains) doses of KCl between 0 and 10.000 µg/plate were tested with and without metabolic activation. No significant increases in mutation frequencies were noted (Mortelmans1986)

Lymphoma cell mutation assays:

Two independent laboratories performed the Mouse Lymphoma Mutation Tests on a range of substances including KCl.

Myhr 1988: A Mouse Lymphoma assay was performed according to OECD TG 476 with KCl in the presence and in the absence of a metabolic activation system.With metabolic activation KCl yielded positive results at 4000 and 5000 µg/ml; without activation it was negative up to 5000 µg/ml. However higher concentrations appeared to be toxic and mutagenic

Mitchell 1988: The L5178Y mouse lymphoma cell forward mutation assay according to the respective OECD Guideline was used to determine the mutagenic activity of potassium chloride (up to 5000 µg/ml) in the presence and in the absence of a metatolic activation system.The different trials revealed different responses , but overall , potassium chloride induced weakly positive responses only in the presence of S9 -mix but not in the absence of a metabolic activation system.

According to the authors these responses indicate that high salt concentrations which affect the ionic balance and the osmotic pressure of the medium, can induce mutations in cells surviving the treatment.(Mitchell 1988, Myhr 1988).

Chromosome aberration tests:

There are reports on the effect of KCl on formation of chromosome aberrations in Chinese hamster ovary cells (CHO) and Chinese hamster Lung (V79) cells:

In a test similar or equivalent to OECD TG 476 potassium chloride induced a significant increase

in Chinese Hamster lung fibroblasts (V79) cells with chromosme aberrations only at the highest test dose (12000 µg/ml) in the absence of a metabolic activation system. Measurements of the osmotic pressure of the medium revealed a twofold increase at this test compound concentration when compared to the normal medium (530 mOsmol/ kg versus 253 mOsmol/kg , Hasegawa 1984)

A test for Chromosome aberrations was carried out in CHO cells treated with hyperosmotic solutions of potassium chloride (140, 150, 160 mM KCl : 527, 544, 568 mOsm/kg H2O versus 296 mOsm/kg H2O in normal medium).and resulted in substantial increases in chromosome aberrations The increases were associated with cytotoxicity (e.g. 70 % survival (Galloway 1986)

As already mentioned in UNEP 2003, it is reasonable to conclude that the increases in mutagenicity and chromosome aberrations observed in these studies are related to cytotoxicity resulting from the high KCl concentrations used. This argument is supported by the studies on the effect of increased osmolarity on genotoxicity in cultured mammalian cells. The reported mutagenic effect of KCl most probably results from a disruption of osmotic balance of cells with a subsequent interference with chromosomal stability. This may result in the clastogenic effects (DNA breakage and chromosome structural instability) due to K+ effects on sequestering of Mg2+ ions required for normal maintenance of chromatin integrity. Other chemicals may also exert such effect (e.g. NaCl, sucrose).

Overall, based on the above considerations, potassium chloride (KCl) was evaluated to be non-mutagenic.

Glycyl-L-glutamine:

For Glycyl-L-glutamine a GLP-compliant Ames test was conducted with and without metabolic activation. At none of the tested concentration (up to 5000 µg/plate) mutagenic potential was observed.

Overall assessment for reaction mass of Glycyl-L-glutamine and potassium chloride:

Based on the data available for the 2 main components of reaction mass of Glycyl-L-glutamine and potassium chloride, and in the absence of synergistic or antagonistic effects, the reaction mass of Glycyl-L-glutamine and potassium chlroide is considered to have no mutagenic potential.