p-(trifluoromethoxy)phenyl isocyanate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

There was no evidence for mutagenic effects of 4-trifluoromethoxyphenyl isocyanate with and without S9 mix in S. typhyimurium strains TA 100, TA 98, TA 1535 and TA 1537. A biologically relevant increase of revertant colony numbers over control levels was not observed. Therefore, 4-trifluoromethoxyphenyl isocyanate was considered to be non-mutagenic in the Salmonella/microsome test.

For the strain E. coli WP2 uvrA a read-across analysis with the OECD QSAR Toolbox v4.5 was performed. For Categorization the profiler DNA binding by OECD was used, which showed the following alert: Acylation >> Isocyanates and Isothiocyanates.
All of the seven isocyanates included in the final prediction were negative in Ames Tests with the strain E. coli WP2 uvr A with and without metabolic activation.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

13 Oct 2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
OECD QSAR Toolbox v4.5

2. MODEL (incl. version number)
OECD QSAR Toolbox v4.5 - Read-Across Analysis

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
FC(F)(F)Oc1ccc(cc1)N=C=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
The Ames mutagenicity for strain E. coli WP2 uvr A with and without metabolic activation was predicted by read-across analysis with the OECD QSAR Toolbox v4.5. For Categorization the profiler DNA binding by OECD was used, which showed the following alert: Acylation >> Isocyanates and Isothiocyanates. The prediction was then based on the most similar isocyanates having the same alert.
All of the seven isocyanates included in the final prediction were negative in Ames Tests with the strain E. coli WP2 uvr A with and without metabolic activation. Therefore, there is high reliability in the prediction that the registered substance is also negative in E. coli WP2 uvr A.

5. APPLICABILITY DOMAIN
As a Comparison with other substances was performed there is no defined applicability domain

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Software tool(s) used including version: OECD QSAR Toolbox v4.5
- Model(s) used: OECD QSAR Toolbox v4.5 - Read-Across Analysis
- Model description: see field 'Justification for non-standard information' and 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information' and 'Attached justification'

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

FC(F)(F)Oc1ccc(cc1)N=C=O

Species / strain / cell type:

E. coli WP2 uvr A

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

no mutagenic potential (based on QSAR/QSPR prediction)

Conclusions:

All of the seven isocyanates included in the final prediction were negative in Ames Tests with the strain E. coli WP2 uvr A with and without metabolic activation. Therefore, the registered substance is also predicted to be negative for strain E. coli WP2 uvrA.

Executive summary:

The Ames mutagenicity for strain E. coli WP2 uvr A with and without metabolic activation was predicted by read-across analysis with the OECD QSAR Toolbox. For Categorization the profiler DNA binding by OECD was used, which showed the following alert: Acylation >> Isocyanates and Isothiocyanates.
All of the seven isocyanates included in the final prediction were negative in Ames Tests with the strain E. coli WP2 uvr A with and without metabolic activation.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

The mutagenic potential of 4-trifluoromethoxyphenyl 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. The plate incorporation method was used.

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

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:

S-9 mix

Test concentrations with justification for top dose:

first test: 0, 20, 100, 500, 2500, 12500 µg/plate
repeat: 0, 0.16, 0.8, 4, 20, 100 µg/plate

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: endoxane, trypaflavine, 2-aminoanthracene

Species / strain:

E. coli WP2

Metabolic activation:

not applicable

Genotoxicity:

other: not tested

Cytotoxicity / choice of top concentrations:

other: not tested

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Doses up to 4 µg per plate did not cause any bacteriotoxic effects: Total bacteria counts remained unchanged and no growth inhibition was observed. In higher dose ranges the test substance was bacteriotoxic, maily without S-9 mix. Therefore this range could only be used with limitations up to 500 µg/plate. Substance precipitation occurred at the dose of 2500 µg per plate and above.

Conclusions:

There was no evidence for mutagenic effects of 4-trifluoromethoxyphenyl isocyanate with and without S9 mix. A biologically relevant increase of revertant colony numbers over control levels was not observed. Therefore, 4-trifluoromethoxyphenyl isocyanate was considered to be non-mutagenic in the Salmonella/microsome test.

Executive summary:

The mutagenic potential of 4-trifluoromethoxyphenyl 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 4-trifluoromethoxyphenyl isocyanate with and without S9 mix. A biologically relevant increase of revertant colony numbers over control levels was not observed. Therefore, 4-trifluoromethoxyphenyl isocyanate was considered to be non-mutagenic in the Salmonella/microsome test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

No signs for a mutagenic effect of 4-trifluoromethoxyphenyl isocyanate in doses up to 2 x 100 mg/kg bw was evident. No relevant, treatment related alteration of the ratio polychromatic to normochromatic erythrocytes was found. the positive control (Tremonin) had a clear mutagenic effect. Under the conditions of the test 4-trifluoromethoxyphenyl isocyanate was negative in the in-vivo micronucleus test.

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

The micronucleus test was employed to investigate 4-trifluoromethoxyphenyl isocyanate in male and female mice for a possible clastogenic effect on the chromosomes of bone-marrow erythroblasts. The known clastogen and cytostatic agent, Trenimon, served as positive control. The treated animals received 2 oral application within 24 hoursof the test substance, the positive control was applied intraperitoneal. The femoral marrow of groups treated with 4-trifluoromethoxyphenyl isocyanate was prepared 6 hours after administration.

GLP compliance:

no

Type of assay:

micronucleus assay

Species:

mouse

Strain:

other: Bor: NMRI (SPF Han)

Sex:

male/female

Route of administration:

oral: gavage

Duration of treatment / exposure:

2 oral treatments within 24 hours

Frequency of treatment:

2 oral treatments within 24 hours

Post exposure period:

Animals were sacrificed 6 after the second application

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

2 x 100 mg/kg bw

Dose / conc.:

50 mg/kg bw/day (nominal)

Remarks:

2 x 50 mg/kg bw

No. of animals per sex per dose:

5 male and 5 female mice/group

Control animals:

yes, concurrent vehicle

Tissues and cell types examined:

femoral marrow

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

in the 2 x 50 mg/kg bw no signs of toxicity; in the 2 x 100 mg/kg bw group 11 of 20 animals died

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

No signs for a mutagenic effect of 4-trifluoromethoxyphenyl isocyanate in doses up to 2 x 100 mg/kg bw was evident. No relevant, treatment related alteration of the ratio polychromatic to normochromatic erythrocytes was found. the positive control (Tremonin) had a clear mutagenic effect.

Conclusions:

No signs for a mutagenic effect of 4-trifluoromethoxyphenyl isocyanate in doses up to 2 x 100 mg/kg bw was evident. No relevant, treatment related alteration of the ratio polychromatic to normochromatic erythrocytes was found. the positive control (Tremonin) had a clear mutagenic effect. Under the conditions of the test 4-trifluoromethoxyphenyl isocyanate was negative in the in-vivo micronucleus test.

Executive summary:

The micronucleus test was employed to investigate 4-trifluoromethoxyphenyl isocyanate in male and female mice for a possible clastogenic effect on the chromosomes of bone-marrow erythroblasts. The known clastogen and cytostatic agent, Trenimon, served as positive control. The treated animals received 2 oral application of the test substance within 24 hours, the positive control was applied intraperitoneal. The femoral marrow of groups treated with 4-trifluoromethoxyphenyl isocyanate was prepared 6 hours after administration.

No signs for a mutagenic effect of 4-trifluoromethoxyphenyl isocyanate in doses up to 2 x 100 mg/kg bw was evident. No relevant, treatment related alteration of the ratio polychromatic to normochromatic erythrocytes was found. the positive control (Tremonin) had a clear mutagenic effect. Under the conditions of the test 4-trifluoromethoxyphenyl isocyanate was negative in the in-vivo micronucleus test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Both tests (Ames test and micronucleus test on mice) were negative.

Short description of key information:
A valid bacterial reverse mutation assay (Ames test) and an in-vivo chromosome aberration assay (micronuleus test) on mice are available.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Due to the results of the Ames test and Micronucleus test a classification according to Regulation (EC) No 1272/2008 is not justified.