19-Norpregn-5(10)-ene-21-nitrile, 17-hydroxy-3-oxo-, (17.alpha.)-

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jan 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

21 July 1997

Deviations:

yes

Remarks:

- only one experiment was performed

Principles of method if other than guideline:

The current OECD TG 471 requires at least 5 test strains and the use of E. coli WP2 strains or Salmonella typhimurium TA 102 to detect certain oxidizing mutagens, cross-linking agents and hydrazines. However, the substance is not a highly reactive agent and is therefore not expected to be a cross-linking agent, has no oxidizing properties and is no hydrazine. Thus, a GLP test according to former versions of OECD TG 471 without E. coli WP2 strains or Salmonella typhimurium TA 102 is considered as sufficient to evaluate the mutagenic activity of the substance in this bacterial test system.

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

17 alpha-Cyanomethyl-17 beta-hydroxy-5(10)-estren-3-one

EC Number:

613-855-5

Cas Number:

65928-65-6

Molecular formula:

C20 H27 N O2

IUPAC Name:

17 alpha-Cyanomethyl-17 beta-hydroxy-5(10)-estren-3-one

Constituent 2

Reference substance name:

612-855-5

IUPAC Name:

612-855-5

Details on test material:

Purity not specified

Method

Target gene:

Histidine gene locus

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1537

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1535

Additional strain / cell type characteristics:

not applicable

Species / strain 3

Species / strain / cell type:

S. typhimurium TA 102

Additional strain / cell type characteristics:

not applicable

Species / strain 4

Species / strain / cell type:

S. typhimurium TA 100

Additional strain / cell type characteristics:

not applicable

Species / strain 5

Species / strain / cell type:

S. typhimurium TA 98

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital/ß-Naphthoflavone induced male rat liver S9 mix

Test concentrations with justification for top dose:

3, 10, 33, 100, 333, 1000, 2500, 5000 µg/plate

Vehicle / solvent:

Ethanol

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: without metabolic activation: 4-nitro-o-phenylenediamine; with metabolic activation: 2-aminoanthracene

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate -S9 mix and ≥ 2500 µg/plate +S9 mix

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate -S9 mix

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

≥ 333 µg/plate -S9 mix and ≥ 1000 µg/plate +S9 mix

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate -S9 mix

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Any other information on results incl. tables

Toxic effects occurred in the strains TA 1535 and TA 100 (only without S9 mix) as well as in the strains TA 1537 and TA 102 (both with and without S9 mix) at higher concentrations.

 

No substantial increases in revertant colony numbers of any of the five tester strains were observed following treatment with the test item at any concentration level, either in the presence or absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance.

 

Appropriate control mutagens were used as positive controls. They showed a distinct increase of induced revertant colonies.

Applicant's summary and conclusion

Conclusions:

The mutagenic potential of the test substance was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 in the presence and absence of S9 mix according to OECD TG 471. Evidence of mutagenic activity was not seen up to the maximum recommended dose level of 5000 µg/plate. No substantial increases in revertant colony numbers of any of the five tester strains were observed at any dose level in the presence and absence of metabolic activation. There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. Therefore, the test substance was considered to be non-mutagenic in the Salmonella typhimurium reverse mutation assay.

Executive summary:

In a reverse gene mutation assay in bacteria according to OECD TG 471 (adopted 21 July 1997), strains TA98, TA100, TA102, TA1535, and TA1537 of S. typhimurium were exposed to 5-Dehydromethyketon (100 % a.i.) in ethanol at concentrations of 3, 10, 33, 100, 333, 1000, 2500, 5000 µg/plate in the presence and absence of mammalian metabolic activation.

No substantial increases in revertant colony numbers of any of the five tester strains were observed following treatment with the test item at any concentration level, either in the presence or absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence of induced mutant colonies over background.

This study is classified as acceptable. This study satisfies the requirement for Test Guideline OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data.