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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientific acceptable and well documented - only 4 strains tested

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1980

Report date:

1980

Materials and methods

Principles of method if other than guideline:

The mutagenic potential of phenyl isocyanate was examined in the Salmonella/microsome test. Bacteria of four histidine auxotrophic Salmonella typhimurium LT2 mutant strains (TA 98, TA 100, TA 1535, and TA 1537) were exposed to doses up to 12500 µg per plate.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Phenyl isocyanate

EC Number:

203-137-6

EC Name:

Phenyl isocyanate

Cas Number:

103-71-9

Molecular formula:

C7H5NO

IUPAC Name:

isocyanatobenzene

Details on test material:

content: 100%

Method

Species / strain

Species / strain / cell type:

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

Additional strain / cell type characteristics:

other: Firstly, they are deep rough since certain lipopolysaccharide side chains are missing in the bacterial cell wall. Secondly, their reduced ability to repair damage from UV light (e.g. thymidine dimers) allows the phenotypic detection of mutation events

Metabolic activation:

with and without

Metabolic activation system:

S9 mix

Test concentrations with justification for top dose:

0, 20, 100. 500, 2500, 12500 µg/plate

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: Endoxan, Trypaflavin

Details on test system and experimental conditions:

Ames test

Results and discussion

Test results

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

up to 2500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Doses up to 2500 µg per plate did not cause any bacteriotoxic effects: Total bacteria counts remained unchanged and no growth inhibition was observed. Substance precipitation occurred at the dose of 2500 µg per plate and above.

Applicant's summary and conclusion

Conclusions:

Interpretation of results: negative

Executive summary:

The mutagenic potential of phenyl isocyanate was examined in the Salmonella/microsome test. Bacteria of four histidine auxotrophic Salmonella typhimurium LT2 mutant strains (TA 98, TA 100, TA 1535, and TA 1537) were exposed to doses up to 12500 µg per plate.

There was no evidence for mutagenic effects of phenyl isocyanate with and without S9 mix. A biologically relevant increase of revertant colony numbers over control levels was not observed. Therefore, phenyl isocyanate was considered to be non-mutagenic in the Salmonella/microsome test.