4,4'-ethylidenediphenyl dicyanate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The reverse mutation assay was performed according to EU-test method B.13/14 with 5 Salm. typh. strains (TA98, TA100; TA1535, TA1537, TA1538) with and without metabolic activation. Tested concentrations ranged from 0.3 up to 1000 ug/plate. The test item was found to be non-mutagenic in this study. The chromosome aberration assay was performed according to EU-test method B.10 with Chinese hamster ovary cells with and without metabolic activation. With S-9 mix, toxicity was demonstrated in the preliminary assay at 16 micrograms/ml an£ there was a 55% reduction in cell count at 25 ug/ml in the main assay. Without S- 9, toxicity was demonstrated by a 48% reduction in mitotic index at 31 ug/ml in the preliminary assay; no toxicity was noted in the main assay. The test house stated that the type of chromosome damage observed (mainly exchanges) cannot merely be ascribed to toxicity, but has to be considered evidence of true clastogenicity of the test substance. The notifier has been requested to perform an in vivo test, preferably the micronucleus test, to investigate further the potential mutagenicity of the substance The substance must be regarded as clastogenic in presence of S9-mix in this study. The micronucleus test assay was performed according to EU-test method B.12 with mice (5 males & 5 females per dose group). Tested concentrations ranged from 37 -150 mg/kg, vehicle was corn oil. The following effects observed: One death (replaced with another animal) at 150 rng/kg. Mild trerrors and clonic convulsions also seen at 150 rng/kg.). No clear change in the PiN ratio. However, the toxic signs noted, and the liver damage seen in the earlier sub-acute study, suggest that the substance does enter the blood system and hence the bone marrow is likely to be exposed to the substance and/or metabolites. The test item was found to be non-mutagenic in this study.

Link to relevant study records

Reference

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: test data from ELINCS-notification obtained from ECHA on 10-June-2010 (EC-no. 405-740-1 / notification-no. 91-06-0255-00); performed under GLP and according to EU-testing methods

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Metabolic activation system:

Aroclor-induced rat liver S-9-mix

Test concentrations with justification for top dose:

- Concentration range in the main test (with metabolic activation): 2 - 25 ug/plate
- Concentration range in the main test (without metabolic activation): 6 - 75 ug/plate

Vehicle / solvent:

Dimethylsulfoxide

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

not specified

Positive control substance:

not specified

Details on test system and experimental conditions:

- Exposure period (with metabolic activation): 6 hours
- Exposure period (without metabolic activation): 24 hours

- Fixation time: 26 hours

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

(25 ug/ml)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

(> 75 ug/ml)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

At 25 ug/ml with S9, 5-8% of cells had structural abberations (excluding gaps) as compared with 1-2% of vehicle controls. Abberations at 25 ug/ml were mainly exchanges.

Remarks on result:

other: strain/cell type:

Remarks:

Migrated from field 'Test system'.

Results Preliminary test:

- Species/strain other: as specified above

- Metabolic activation: with & without S9 -mix

- Cytotoxicity: yes (16 ug/ml with S9 -mix) and 31 ug/ml without S9 -mix)

Conclusions:

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

LECY must be regarded as clastogenic in presence of S9-mix in this study

Executive summary:

Submitted as supporting information. The genetic toxicity in-vitro assay was performed according to EU-test method B.10 with Chinese hamster ovary cells with and without metabolic activation. With S9 -mix, toxicity was demonstrated in the preliminary assay at 16 ug/ml and there was a 55% reduction in cell count at 25 ug/ml in the main assay. Without S9 -mix, toxicity was demonstrated by a 48% reduction in mitotic index at 31 ug/ml in the preliminary assay whereas no toxicity was noted in the main assay. The test house stated that the type of chromosome damage observed (mainly exchanges) cannot merely be ascribed to toxicity, but has to be considered evidence of true clastogenicity of the test substance. Based on the clastogenic effects observed in this study, it was suggested to perform an in vivo test, preferably the micronucleus test, to investigate further the potential mutagenicity of the substance.

The test item must be regarded as clastogenic in presence of S9-mix in this study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Additional information

Additional information from genetic toxicity in vitro:

Justification for selection of genetic toxicity endpoint
Reliable data from ELINCS-notification (Klimisch 1)

Justification for classification or non-classification

Based on the data available the substance is not classified or labeled according to Directive 67/548/EEC (DSD) or Regulation 1272/2008/EC (CLP).