Reaction products of m-phenylenebis(methylamine) with 2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane

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:

23 November 2017 - 20 December 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

21 July 1997

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Version / remarks:

31 May 2008

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

4,4'-Isopropylidenediphenol, oligomeric reaction products with 1-chloro-2,3- epoxypropane, reaction products with mphenylenebis(methylamine)

Cas Number:

113930-69-1

IUPAC Name:

4,4'-Isopropylidenediphenol, oligomeric reaction products with 1-chloro-2,3- epoxypropane, reaction products with mphenylenebis(methylamine)

Test material form:

solid

Details on test material:

- Physical appearance: light amber solid
- Storage of test material: at room temperature

Method

Target gene:

Salmonella typhimurium: histidine gene
Escherichia coli: tryprophan gene

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver microsomal enzymes (S9 homogenate) from rats that had been injected intraperitoneally with Aroclor 1254 (500 mg/kg body weight).

Test concentrations with justification for top dose:

Dose range finding test (TA100 and WP2uvrA, with and without S9): 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate (reported as part of the first experiment)
First experiment (TA1535, TA 1537 and TA98): without and with S9: 0.55, 1.7, 5.4, 17, 52 and 164 μg/plate
Second experiment (all strains) without and with S9: 0.55, 1.7, 5.4, 17, 52 and 164 μg/plate
Second additional experiment (TA1535, TA1537, TA98 and TA100) without S9: 0.017, 0.055, 0.17, 0.55, 1.7 and 5.4 μg/plate

Vehicle / solvent:

- Solvent used: dimethyl sulfoxide
- Justification for choice of solvent/vehicle: the solvent is according to OECD guideline 471 and the test substance dissolved in DMSO (based on visual assessment).

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

2-nitrofluorene

sodium azide

methylmethanesulfonate

other: ICR-191; 2-aminoanthracene

Remarks:

See table 1 for more details on postive control substances

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 +/- 4 hours

NUMBER OF REPLICATIONS: 3

PERFORMANCE OF THE ASSAY: The following solutions were successively added to 3 ml molten top agar: 0.1 mL of a fresh bacterial culture (10^9 cells/mL) of one of the tester strains, 0.1 mL of a dilution of the test item in DMSO and either 0.5 mL S9-mix (in case of activation assays) or 0.5 mL 0.1 M phosphate buffer (in case of non-activation assays). The ingredients were mixed on a Vortex and the content of the top agar tube was poured onto a selective agar plate. After solidification of the top agar, the plates were inverted and incubated in the dark at 37.0 ± 1.0 °C

CYTOTOXICITY:
- Cytotoxicity was examined by the reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies

COLONY COUNTING:
The revertant colonies were counted automatically with the Sorcerer Colony Counter. Plates with sufficient test item precipitate to interfere with automated colony counting were counted manually. Evidence of test item precipitate on the plates and the condition of the bacterial background lawn were evaluated when considered necessary, macroscopically and/or microscopically by using a dissecting microscope.

Evaluation criteria:

A test item is considered negative (not mutagenic) in the test if:
a) The total number of revertants in the tester strain TA100 or WP2uvrA is not greater than two (2) times the concurrent vehicle control, and the total number of revertants in tester strains TA1535, TA1537 or TA98 is not greater than three (3) times the concurrent vehicle control.
b) The negative response should be reproducible in at least one follow-up experiment.

A test item is considered positive (mutagenic) in the test if:
a) The total number of revertants in the tester strain TA100 or WP2uvrA is greater than two (2) times the concurrent vehicle control, or the total number of revertants in tester strains TA1535, TA1537, TA98 is greater than three (3) times the concurrent vehicle control.
b) In case a follow up experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one follow up experiment.

In addition to the criteria stated above, any increase in the total number of revertants should be evaluated for its biological relevance including a comparison of the results with the historical control data range.

Acceptability criteria:
a) The vehicle control and positive control plates from each tester strain (with or without S9-mix) must exhibit a characteristic number of revertant colonies when compared against relevant historical control data generated at this laboratory.
b) The selected dose-range should include a clearly toxic concentration or should exhibit limited solubility as demonstrated by the preliminary toxicity range-finding test or should extend to 5 mg/plate.
c) No more than 5% of the plates are lost through contamination or some other unforeseen event. If the results are considered invalid due to contamination, the experiment will be repeated.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

In experiment 1: at and above 164 µg/plate; in experiment 2: at and above 17 µg/plate; in experiment 2A: at 5.4 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

In experiment 1: at and above 164 µg/plate; in experiment 2: at and above 5.4 µg/plate; in experiment 2A: at 5.4 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

In experiment 1: at and above 164 µg/plate; in experiment 2: at and above 17 µg/plate; in experiment 2A: at 5.4 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

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:

In experiment 1: at and above 164 µg/plate; in experiment 2: at and above 17 µg/plate; in experiment 2A: at 5.4 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

In experiment 1: at and above 164 µg/plate; in experiment 2: at and above 52 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Due to severe cytotoxicity in the absence of S9-mix in all Salmonella typhimurium strains, an additional second experiment was performed with only Salmonella typhimurium strains in the absence of S9.

PRECIPITATION:
- Dose-range finding/first experiment: at the start and at the end of the incubation period at concentrations of 1600 and 5000 µg/plate.
- Second experiment: only at the end of the incubation period precipitation was observed at the concentrations of 52 and 164 µg/plate in tester strains TA1537 and TA98 and at 164 µg/plate in tester strains TA1535, TA100 and WP2uvrA in the absence of S9 mix. In the presence of S9-mix precipitate was observed at 164 µg/plate in tester strains TA98 and WP2uvrA.
- Second additional experiment: no precipitation observed

CYTOTOXICITY
- Dose-range finding/first experiment: observed in all tester strains in the presence and in the absence of S9.
- Second experiment: observed in all tester strains in the presence and in the absence of S9.
- Second additional experiment: ovbserved in all Salmonella typhimurium strains in the absence of S9.

MUTAGENICITY
- Dose-range finding/first experiment: no
- Second experiment: no
- Second additional experiment: no

HISTORICAL CONTROL DATA
- The negative control values and the strain-specific positive control values were within the laboratory historical control data ranges.
- Except the responses for TA1535 in the first experiment in the presence of S9-mix where results were observed (one plate) below the laboratory historical control data range. The purpose of the positive control is as a reference for the test system, where a positive response is required to check if the test system functions correctly. Since the mean number of colonies was within the historical control data range and all values were more than 3 times greater than the concurrent solvent control values, this deviation in the plate count of the positive control had no effect on the results of the study.

Applicant's summary and conclusion

Conclusions:

The results of an Ames test, performed according to OECD guideline 471 and GLP principles, showed that INCA 460: MXDA Adduct is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.