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Administrative data

Key value for chemical safety assessment

Additional information

Reliable, relevant and adequate data on genotoxicity are available for Guanidine hydrochloride (Ames test) as well as for the read-across substance Guanidine nitrate (Ames test, mouse lymphoma thymidine kinase assay, mammalian cell cytogenetic assay).

Reverse gene mutation in bacteria:

In a reverse gene mutation assay in bacteria according to OECD guideline 471, 1983 strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 of S. typhimurium were exposed to Guanidine hydrochloride (98.5% a.i.) in water at concentrations of 0, 8, 40, 200, 1000 and 5000 µg/plate in the presence and absence of mammalian metabolic activation (S9 mix).

Guanidine hydrochloride was tested up to limit concentrations of 5000 µg/plate. No cytotoxicity was observed. The positive controls induced the appropriate responses in the corresponding strains.

There was no evidence of induced mutant colonies over background.

Similar results were observed with the read-across substance Guanidine nitrate, in a study conducted under the same conditions strains and concentrations. No cytotoxicity and no increase in the number of revertants were observed in all tester strains, with or without metabolic activation up to the limit concentration of 5000 µg/plate.

This finding is supported by data published in the chemical carcinogenesis research information system (CCRIS, 2003): Negative results for Guanidine hydrochloride were obtained in the tester strains TA 1535, TA1537, TA1537, TA98, TA100 and E. coli wp2uvra in a concentration range from 20 to 5000 µg/plate, with and without mammalian metabolic activation.

Gene mutation in mammalian cells:

In a mammalian gene mutation assay according to OECD Guideline 476, L5178 Y (mouse lymphoma thymidine kinase locus) cells cultured in vitro were exposed to Guanidine nitrate (> 99.8 %) in the presence and absence of mammalian metabolic activation at the following concentrations:

Experiment I: 75.0, 150.0, 300.0, 600.0, and 1200.0 µg/mL - with and without S9 mix

Experiment II: 75.0, 150.0, 300.0, 600.0, and 1200.0 µg/mL - with S9 mix

Experiment II: 75.0, 150.0, 300.0, 600.0, and 900.0 µg/mL - without S9 mix

Relevant cytotoxic effects indicated by a relative total growth of less than 50 % of survival in both parallel cultures were observed at 600 µg/mL and above in the second experiment without metabolic activation following 24 hours of treatment. No substantial and reproducible dose dependent increase in mutant colony numbers was observed in both main experiments. No relevant shift of the ratio of small versus large colonies was observed up to the maximum concentration of the test item.

Appropriate reference mutagens were used as positive controls and showed a distinct increase in induced mutant colonies, indicating that the tests were sensitive and valid.

Cytogenetics (Chromosome Aberrations) in mammalian cells:

In a mammalian cell cytogenetic assay similar to OECD Guideline 473, 1997 cultures of a clonal sub-line of a Chinese hamster fibroblast cell line (CHL) were exposed to a large number of chemicals in a comparative test.

Treatment with Guanidine nitrate was performed at a maximum concentration of 0.5 mg/mL (41 x 10-4 M) without metabolic activation. Microscopic analysis: In the experiment no biologically relevant increase in the number of cells carrying structural chromosome aberrations was observed. The aberration rates of the cells after treatment with the test item were close to the range of the solvent control values (< 3 % inclusive gaps). Experimentation in the presence of metabolic activation was not performed.

In conclusion it can be stated that under the experimental conditions reported, i.e. without metabolic activation, Guanidine Nitrate did not induce structural chromosome aberrations as determined by the chromosome aberration test in CHL cells (Chinese hamster cell line) in vitro. The test item is considered to be non-clastogenic in this chromosome aberration test without metabolic activation when tested up to cytotoxic test item concentrations.

From the available data on the test substance as well as the read-across substance Guanidine nitrate it can be concluded that Guanidine hydrochloride is non-mutagenic.

Justification for read-across:

Guanidine hydrochloride and Guanidine nitrate dissociate in aqueous media to yield the Guanidine ion and the respective anion. Therefore it is reasonable to discuss the effects of the ions separately.

The Chloride ion is a naturally occurring essential ion in human beings with well-known metabolism and mechanisms of action as described in standard textbooks on pharmacology and physiology. As well it is found as salt in the Earth´s crust and is dissolved in seawater.

Effects of Guanidine hydrochloride are expected to be based primarily on the guanidine ion. The physiological processing of the Guanidine ion is expected to be independent of the individual source. Therefore read-across from Guanidine nitrate for effects of Guanidine dissociated from Guanidine hydrochloride is considered valid. As no genotoxic effects were observed with the read-across substance Guanidine nitrate, there is no need to distinguish between Guanidine and Nitrate effects.

Justification is supported by similar findings in a bacterial reverse mutation assay for both substances.

A more detailed justification is attached and outlined in CSR chapter 1.1.2 as well.


Justification for selection of genetic toxicity endpoint
No single key study has been selected, since all available studies were negative for genotoxicity.

Short description of key information:
Reliable, relevant and adequate data on genotoxicity are available for Guanidine hydrochloride (Ames test) as well as for the read-across substance Guanidine nitrate (Ames test, mouse lymphoma thymidine kinase assay, mammalian cell cytogenetic assay).
No evidence for genotoxicity has been observed in any test. Thus, Guanidine hydrochloride is considered to be non-mutagenic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

There is no evidence for genotoxic properties from gene mutation assays in bacteria and mammalian cells, as well as chromosome aberration in mammalian cells. According to CLP, EU GHS (Regulation (EC) No 1272/2008), as well as Directive 67/5489 EEC Guanidine hydrochloride does not need to be classified for genetic toxicity.