o-(p-isocyanatobenzyl)phenyl isocyanate

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:

September 9th 1996 to 21.10.1996

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

Adopted: 26 May 83, No 471

Deviations:

yes

Remarks:

five tester strains tested, no E-coli or TA 102 included, TA 1538 tested only with S9 tested

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

o-(p-isocyanatobenzyl)phenyl isocyanate

EC Number:

227-534-9

EC Name:

o-(p-isocyanatobenzyl)phenyl isocyanate

Cas Number:

5873-54-1

Molecular formula:

C15H10N2O2

IUPAC Name:

1-isocyanato-2-[(4-isocyanatophenyl)methyl]benzene

Details on test material:

- Name of test material (as cited in study report): 2,4'-Diisocyanoto diphenylmethane, MDI, CAS N° 5873-54-1 (Bayer)

SOLVENT: dimethyl sulphoxide containing 0.02-0.1% water; (DMSO for IR spectroscopy (Merck));

POSITIVE CONTROL: 2-aminoanthracene (Aldrich)

Method

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1538

Details on mammalian cell type (if applicable):

CELLS USED
- Type and source of cells: Bruce Ames

Species / strain 2

Species / strain / cell type:

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

Details on mammalian cell type (if applicable):

CELLS USED
- Type and source of cells: Bruce Ames

Metabolic activation:

with and without

Metabolic activation system:

Type and composition of metabolic activation system:
- source of S9: Rat liver, aroclor 1254 induced male Sprague Drawley rats
- method of preparation of S9 mix: preparation according directions of Ames et al. 1975 Proc. nat. Acad. Sci (USA) 70, 2281-2285 and Maron and Ames 1983, Mutation Res. 113, 173-215
- concentration or volume of S9 mix and S9 in the final culture medium: 10 % (experiment 1 and 2), experiment 3: 30%
- quality controls of S9 (e.g., enzymatic activity, sterility, metabolic capability): yes

Test concentrations with justification for top dose:

experiment 1: 0, 16, 50, 158, 500, 1581, 5000 µg/plate , experiment 2: 0, 15, 30, 60, 120, 240 toxicity observed at highest dose, 3rd experiment with S9 dose range similar to 2nd experiment)

Vehicle / solvent:

yes Ethylene glycol dimethyether (EGDE, dryed with Baylith TE 144, a molecular sieve)

Controls

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

sodium azide

other:

Remarks:

nitrofurantoin, 4-nitro-1,2-phenylene diamine, 2-aminoanthracene

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration: triplicate
- Number of independent experiments: 3 (main test 2 experiments, amendment 1 experiment)

METHOD OF TREATMENT/ EXPOSURE:
- Test substance added in medium; in agar (plate incorporation); preincubation;

Rationale for test conditions:

according guideline OECD TG 471

Evaluation criteria:

criteria according Ames et al. (1973) Proc. nat. Acad. Sci (USA) 70, 782-786 and Maron and Ames 1983 Mutation Res. 113, 173-215

Statistics:

Standard deviation, mean

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

The Salmonella/microsome test employing doses up to 5000 µg/plate, showed 2,4'-MDI to produce bacteriotoxic effects only at 120 µg/plate and above. Therefore 1581 µg/plate and above could not be used for assessment.

Applicant's summary and conclusion

Conclusions:

In a Salmonella /microsome assay no evidence of a mutagenic potential of 2,4'-MDI was noted under the test conditions used.

Executive summary:

The mutagenic potential of 2,4-MDI was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 in the presence and absence of S9 mix. Evidence of mutagenic activity was not seen. No biologically relevant increase in the mutant count, in comparison with the negative controls, was observed. Based on this test, the test substance was considered to be non-mutagenic without and with S9 mix in the Salmonella/microsome test.