sodium 4,4-dimethyl-2,5-dioxoimidazolidin-1-ide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The genotoxicity of NaDMH has been investigated using the Ames test, in this assay NaDMH did not cause any genotoxic effects via gene mutation. A further five assays were carried out on the analogue chemical DMH: the Ames test and the Mouse Lymphoma mutagenesis assay for gene mutation, the cytogenicity study on ovary cells in vitro for chromosome aberration and the Unscheduled DNA synthesis assay in rat hepatocytes. In all assays DMH did not cause any genotoxic effects via gene mutation, chromosome aberration, cytogenicity or Unscheduled DNA synthesis.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 17-July 16, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study was performed in compliance with GLP standards and in accordance with the Guidelines.

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

see data source

Type of assay:

bacterial reverse mutation assay

Target gene:

Not applicable

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Additional strain / cell type characteristics:

not applicable

Species / strain / cell type:

S. typhimurium TA 102

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbitone/Beta-Naphthoflavone activated rat liver S9

Test concentrations with justification for top dose:

Concentration range in the main test (with metabolic activation): 50 - 5000 µg/plate
Concentration range in the main test (without metabolic activation): 50 - 5000 µg/plate

Vehicle / solvent:

Dimethyl sulphoxide

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

for TA100 an TA1535

Migrated to IUCLID6: ENNG

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

for TA102

Migrated to IUCLID6: MMC

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

for TA1537

Migrated to IUCLID6: 9AA

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

for TA98

Migrated to IUCLID6: 4NQO

Details on test system and experimental conditions:

The strains were obtained from the University of California at Berkeley on culture discs and were stored at -196°C in a Statebourne liquid nitrogen freezer. In this assay, overnight sub-cultures of the appropriate coded stock cultures were prepared in nutrient broth and incubated at 37°C for approximately 10 hours. Each culture was monitored spectrophotometrically for turbidity with titres determined by viable count analysis on nutrient agar plates. The strains were treated with suspensions of the test material using the Ames plate incorporation method at five dose levles, in triplicate, both with and without the addition of a rat liver homogenate metabolising system. The dose range was determined in a preliminary toxicity assay and was 50 to 5000 micrograms/plate in the first experiment. The experiment was repeated on a separate day using the same dose range as Exp. 1, fresh cultures of the bacterial strains and fresh test material formulations.

Evaluation criteria:

There are several criteria for determining a positive result, such as a dose-related increase in revertant frequency over the dose range tested and/or a reproducible increase at one or more concentrations in at least one bacterial strain with or without metabolic activation. Biological relevance of the results will be considered first, statistical methods, as recommended by the UKEMS (5) can also be used as an aid to evaluation, however, statistical significance will not be the only determining factor for a positive response.
A test material will be considered non-mutagenic (negative) in the test system if the above criteria are not met.

Statistics:

All tester strain cultures should be in the approximate range of 1 to 9.9 x109 bacteria per ml.
There should be a minimum of four non-toxic test material dose levels.
There should be no evidence of excessive contamination.
All tester strain cultures exhibit a characteristic number of spontaneous revertants per plate in the vehicle and untreated controls.
The appropriate characteristics for each tester strain have been confimed (rfa, cell-wall, mutation etc.)

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Remarks:

> 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Remarks:

> 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

The substance caused no visible reduction in the growth of the bacterial lawn at any dose level.
The substance was, therefore, tested up to the maximum recomended dose level of 5000 micrograms/plate. A light precipitate (oily in appearance) was observed at 5000 micrograms/plate, this did not prevent the scoring of revertant colonies.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

The test material was considered to be non-mutagenic under the conditions of this test.

Executive summary:

NaDMH was considered to be non-mutagenic under the conditions of this test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Genetic toxicity studies carried out on NaDMH

 

Thompson & Bowles (2006) – reliability 1

Reverse Mutation Assay using Salmonella Typhimurium (Ames Test)

Type of genotoxicity: Gene mutation

Type of study: bacterial reverse mutation assay

Genetic toxicity studies carried out on DMH

 

Haworth(1982) – reliability 1

Salmonella-microsome pre-incubation assay (Ames test)

Type of genotoxicity: Gene mutation

Type of study: bacterial reverse mutation assay

 

Jagannath(1978) – reliability 2

Mutagenicity evaluation of dimethylhydantoin in the Ames Salmonella/Microsome plate test

Type of genotoxicity: Gene mutation

Type of study: bacterial reverse mutation assay

 

Thilagar(1982) – reliability 2

Cytogenicity study Chinese Hamster Ovary (CHO) cells in vitro

Type of genotoxicity: Chromosome aberration

Type of study: In vitro mammalian chromosome aberration test

 

Kirby(1983) - reliability 2

L5178Y TK+/- Mouse Lymphoma Mutagenesis Assay

Type of genotoxicity: Gene mutation

Type of study: mammalian cell gene mutation assay

 

 

Thilagar(1982) - reliability 1

Unscheduled DNA synthesis in primary cultures of rat hepatocytes (by autoradiography)

Type of genotoxicity: DNA damage and/or repair

Type of study: DNA damage and/or repair, Unscheduled DNA synthesis in mammalian cells in vitro

 

Conclusion:

The study carried out on the NaDMH deonstrated that 5,5 -dimethylhydantion, sodium salt exhibited no genotoxic effects.

Further more all DMH studies demonstrated that the analogue chemical dimethylhydantoin did not exhibit genotoxic effects either.

Justification for selection of genetic toxicity endpoint
Study was performed in compliance with GLP standards and in accordance with the Guidelines. Reliable study without restriction.

Justification for classification or non-classification

The study carried out on the NaDMH demonstrated that 5,5 -dimethylhydantion, sodium salt exhibited no genotoxic effects.

Further more all DMH studies demonstrated that the analogue chemical dimethylhydantoin did not exhibit genotoxic effects either.

As previously stated five of the studies have been performed on DMH (Dimethyl Hydantoin) and have been used for read-across purposes. A summary of data for read-across of NaDMH with DMH is given in Section 13.