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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
(1997)
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
HDI oligomers, uretdione
EC Number:
931-288-4
Molecular formula:
(C8H12N2O2)n
IUPAC Name:
HDI oligomers, uretdione
Constituent 2
Reference substance name:
28182-81-2
Cas Number:
28182-81-2
IUPAC Name:
28182-81-2
Details on test material:
- Stability under test conditions: A stability test in the solvent, did not reveal significant degradation of the active ingredient.

Method

Target gene:
histidine locus
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
S9 Mix from rat liver homogenates with Aroclor 1254 for enzyme induction
Test concentrations with justification for top dose:
initial testing (plate incorporation; with and without S9 mix): 50-5000 µg/plate
mutation test 1 (plate incorporation; with and without S9 mix): 0.05-50.0 µg/plate for TA 1535, TA 100, TA 1537, and TA 98; 0.05-158.0 µg/plate for TA 102
mutation test 2 (preincubation, with and without S9 mix): 0.05-50.0 µg/tube for TA 1535, TA 100, TA 1537, and TA 98; 0.05-158.0 µg/tube for TA 102
Vehicle / solvent:
DMSO (dried with molecular sieve, 0.3 nm)
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: Na-azide (NaN3, only TA 1535), nitrofurantoin (NF, only TA 100), 4-nitro-1,2-phenylene diamine (4-NPDA, TA 1537 and TA 98), mitomycin C (MMC, only TA 102), cumene hydroperoxide (Cumene, only TA 102), 2-aminoanthracene (2-AA, all strains)
Remarks:
The positive controls NaN3, NF, 4-NPDA, MMC, and Cumene were only used without S9 mix; the positive control 2-AA was used with S9 mix.
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar for dose selection (50-5000 µg/plate, with and without S9 mix); in agar (plate incorporation) for initial testing (0.05-50.0 µg/plate, with and without S9 mix); as preincubation testing for independent repeat (0.05-50.0 µg/tube, with and without S9 mix; preincubation for 20 min. at 37°C).
Testings for each strain and dose was performed in triplicate, which is also valid for solvent and positive controls.

DETERMINATION OF CYTOTOXICITY
- background growth
- mutant count: A toxic effect was assumed when there was a marked and dose-dependent reduction in the mutant count per plate, compared to the negative controls.
Evaluation criteria:
A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 100 and TA 98 this increase should be about twice that of negative controls, whereas for TA 1537, at least a threefold increase should be reached. For TA 102 an increase of about 100 mutants should be reached. Otherwise, the result is evaluated as negative. However, these guidelines may be overruled by good scientific judgment.
In case of questionable results, investigations should continue, possibly with modifications, until a final evaluation is possible.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Evidence of mutagenic activity of Desmodur N 3400 was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed.
The positive controls had a marked mutagenic effect, as was seen by a biologically relevant increase in mutant colonies compared to the corresponding negative controls.

ADDITIONAL INFORMATION ON CYTOTOXICITY: Doses up to and including 1.6 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a strong, strain-specific bacteriotoxic effect, so that this range could only be used to a limited extent up to and including 50 µg per plate for assessment purposes.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Executive summary:

A bacterial reverse mutation assay (Ames) according to OECD TG 471 was conducted for the evaluation of point mutagenic effects. In this assay 5 strains of Salmonella typhimurium were used (TA 1535, TA 100, TA 1537, TA 98, and TA 102) and the assay was conducted with and without S9 mix. The test substance was investigated in a plate incorporation test in doses up to 5000 µg/plate. The independent repeat was performed as preincubation modification (20 minutes at 37 °C) using doses up 158 µg/tube.

Doses up to and including 1.6 µg per plate did not cause any bacteriotoxic effects. Total bacteria counts remained unchanged and no inhibition of growth was observed. At higher doses, the substance had a strong, strain-specific bacteriotoxic effect, so that this range could only be used to a limited extent up to and including 50 µg/plate for assessment purposes. No biologically relevant increase in the mutant count in comparison with the negative controls was observed, therefore, the test substance was considered to be non-mutagenic in the plate incorporation as well as in the preincubation modification of the Ames test.