Benzonitrile

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Several negative Ames tests are available including a GLP guideline study according to OECD 471 (Microtest, 1988). A negative Sister Chromatide exchange assay (NTP, 1988) and a negative mouse lymphoma mutagenesis assay (Microbiological Associates, 1982) was reported as well as ambiguous results in in vitro Chromosome Aberration (NTP, 1988) and Chromosomal loss studies (Whittaker, 1990).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial gene mutation assay

Species / strain / cell type:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

S9-Mix from Aroclor 1254 induced rat liver

Test concentrations with justification for top dose:

0.08, 0.4, 2, 10 and 50 mg/ml of treatment solutions
Final concentration (µg/plate) 8, 40, 200, 1000, and 5000

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-nitrofluorene, sodium azide, 9-aminoacridine, 2-aminoanthracene

Key result

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Negative (solvent) and positive control treatments were included for all strains in both experiments. The mean numbers of revertant colonies on negative control plates all fell within acceptable ranges, and were significantly elevated by positive control treatments. No Benzonitrile treatment of any tester strain, either in the absence or presence of S-9, resulted in the two-fold (strains TA98 and TA100) or three-fold (strains TA 1535, TA1537 and TA 1538) increases in revertant numbers sufficient to indicate that an induction of mutation had occurred. It is concluded that Benzonitrile was unable to induce mutation in five strains of Salmonella typhimurium when tested up to 5000 µg/plate, either in the absence or presence of a rat liver metabolic activation system.

Conclusions:

Interpretation of results (migrated information):
negative

Benzonitrile was unable to induce mutation in five strains of Salmonella typhimurium when tested up to 5000 µg/plate, either in the absence or presence of a rat liver metabolic activation system.

Executive summary:

In a reverse gene mutation assay in bacteria, with five strains (TA98, TA100, TA1535, TA1537 and TA1538) of S. typhimurium were exposed to Benzonitrile (98.56%) in sterile analytical grade anhydrous dimetyl sulphoxide (DMSO) at concentrations of 0.08, 0.4, 2, 10 and 50 µg/plate in the presence and absence of mammalian metabolic activation of a rat liver post-mitochondrial fraction (S-9).

Benzonitril was tested up to limit concentration of 5000 µg/plate. No evidence of toxicity was observed in a range-finder experiments, and the same series of concentrations was therefore retained for treatment of the remaining strains in both experiments. The mean numbers of revertant colonies on negative control plates all fell within acceptable ranges, and were significantly elevated by positive control treatments.

No Benzonitrile treatment of any strain, either in the absence or presence of S-9, resulted in the two-fold (strains TA98 and TA100) or three-fold (strains TA 1535, TA1537 and TA 1538) increases in revertant numbers sufficient to indicate that an induction of mutation had occurred.

This study is classified as acceptable. This study satisfies the requirement for Test Guideline OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1996

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

S9 (Arocol 1254 iduced rat or hamster liver)

Test concentrations with justification for top dose:

33 - 3333 µg/plate

Key result

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

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

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results:
negative

Benzonitrile does not induce reverse mutation in Salmonella Typhimurium.

Executive summary:

Benzonitrile does not induce reverse mutation in Salmonella Typhimurium.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1984

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

S9 (Arocol 1254 iduced rat or hamster liver)

Test concentrations with justification for top dose:

33 - 3333 µg/plate

Key result

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

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

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Conclusions:

Interpretation of results:
negative

Benzonitrile does not induce reverse mutation in S. typhimurium up to 3333 µg/plate when used with and without metabolic activation.

Executive summary:

Benzonitrile does not induce reverse mutation in S. typhimurium up to 3333 µg/plate when used with and without metabolic activation.

Reference 4

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S9-mix from Phenobarbital & 5,6-Benzoflavon induced rat liver

Test concentrations with justification for top dose:

20 - 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

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:

cytotoxicity

Remarks:

from 625 µg/plate

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Conclusions:

Interpretation of results:
negative

Benzonitrile does not induce reverse mutation in S. typhimurium TA 1535 up to 7500 µg/plate when used without metabolic activation.

Executive summary:

Benzonitrile does not induce reverse mutation in S. typhimurium TA 1535 up to 7500 µg/plate when used without metabolic activation.

Reference 5

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1988

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

not specified

Remarks:

(data collection)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium, other: no details reported

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9-Mix from Aroclor 1254 induced rat or hamster liver

Test concentrations with justification for top dose:

no data

Species / strain:

other: S. typhimurium TA 1535, TA 97, TA 98 and TA 100

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

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

A genetic assay for histidine reversion testing using Salmonella typhimurium was found to be negative.

Conclusions:

Zeiger et.al (1988) found benzonitrile to have no possitive effect in a histidine reversion test using Salmonella typhimurium.

Executive summary:

Zeiger et.al (1988) found benzonitrile to have no possitive effect in a histidine reversion test using Salmonella typhimurium.

Reference 6

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

2003

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

documentation insufficient for assessment; interpretation of results is questionable (2x increase in the number of MNs is considered a positive effect; no dose-effect-relationship)

Qualifier:

no guideline followed

Principles of method if other than guideline:

MN assay was performed in vitro (V79 cells) according to Matsuoka et al. (Matsuoka A, Yamazaki N, Suzuki T, Hayashi M, Sofuni T (1992) Evaluation of the micronucleus test using a Chinese hamster cell line as an alternative to the conventional in vitro chromosomal aberration test. Mutat Res 272:223–236)

GLP compliance:

no

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Additional strain / cell type characteristics:

not specified

Test concentrations with justification for top dose:

0.001, 0.005, 0.01, 0.1, 1, 10, 100 µM

Vehicle / solvent:

0.04% DMSO

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: vincristine

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

other: ambigous statements

1) benzonitrile exhibited no cytotoxicity in V79 cells, in terms of Neutral red uptake, even when tested up to high medium concentrations (1 mM; data not shown)

2) With 50 mM benzonitrile, the tubulin cytoskeleton was completely destroyed, presumably as a result of general cytotoxicity, as the cells began to detach from the surface.

Conclusions:

Interpretation of results:
ambiguous

The authors conclude that Benzonitril exhibits a weak, but definitely positive test result at concentrations below cytotoxicity. A small (2x) increase in the number of micronucleus was considered a positive effect. Based on the limited available data and the small increase in the number of MNs this conclusion is not considered to be reliable.

Executive summary:

In a mammalian cell cytogenetics assay [in vitro micronucleus (MN)], V79 cell cultures were exposed to benzonitrile in DMSO at concentrations of 0.001, 0.005, 0.01, 0.1, 1, 10, 100, 1000 µM (data for 1 mM not shown) without metabolic activation. Positive controls induced the appropriate response (data not shown). The authors reported an induced 2-fold increase over background as evidence of Ch’some aberration . Results are presented as graphs, only. The control value is 6-7 MN/1000 cells. The maximum increase in MN is 12/1000 cells at 1 µM. Higher concentrations do not increase the number of MNs. A clear dose response has not been shown. In addition, according to OECD 487 the micronuclei frequencies of solvent/vehicle control and untreated cultures are typically between 5-25 micronuclei/1000. Thus the slight increase in the number of MN cannot be regarded as positive result. This study is classified as unacceptable. This study does not satisfy the requirement for Test Guideline In vitro mammalian cytogenetics [OECD 487] for in vitro cytogenetic mutagenicity data.

Reference 7

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1988

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

not specified

GLP compliance:

not specified

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:

S9-mix from Arocol 1245 induced rat liver

Test concentrations with justification for top dose:

without metabolic activation: 200 - 1500 µg/ml
with metabolic activation: 200 - 3000 µg/ml

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 1500 µg/ml

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with

Genotoxicity:

positive

Remarks:

11% aberration vs 1-3% control

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 3000 µg/ml

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

In a first experiment with metabolic activation a total of 72% of the cell had chromosomal aberrations (64% basic, 8% complex) at 1495 µg/ml. In a second experiment with metabolic activation this severe effect could not be verified. The incubation at 1005 – 1993 µg/ml led to an increase in Chromosomal aberration of up to 11% (3% basic, 9% complex). The DMSO control was 3, 1, and 2%. The highest concentration tested (1993 µg/ml) caused cytotoxicity. However, without additional data it cannot be verified that aberrations only occur at cytotoxic concentrations.

Conclusions:

Interpretation of results:
ambiguous with metabolic activation

At a concentration of 1005-1993 µg/ml (with metabolic activation) benzonitrile increased the rate of chromosomal aberration up to 11% (3% basic, 9% complex) compared to 1-3% DMSO. A concentration of 1993 µg/ml was cytotoxic.

Executive summary:

At a concentration of 1005-1993 µg/ml (with metabolic activation) benzonitrile increased the rate of chromosomal aberration up to 11% (3% basic, 9% complex) compared to 1-3% DMSO. A concentration of 1993 µg/ml was cytotoxic.

Reference 8

Endpoint:

in vitro DNA damage and/or repair study

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1990

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 481 (Genetic Toxicology: Saccharomyces cerevisiae, Mitotic Recombination Assay)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

mitotic recombination assay with Saccharomyces cerevisiae

Species / strain / cell type:

Saccharomyces cerevisiae

Additional strain / cell type characteristics:

other: D61.M

Metabolic activation:

not specified

Test concentrations with justification for top dose:

up to 2190µg/ml

Key result

Species / strain:

Saccharomyces cerevisiae

Metabolic activation:

not specified

Genotoxicity:

ambiguous

Remarks:

negative under standard conditions; positive under customized conditions (16h 0°C)

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Conclusions:

Interpretation of results:
ambiguous

Benzonitrile did not induce chromosomal losses under standard conditions (16h, 30°C) up to 2190 µg/ml. Under modified test conditions (4h 30°C + 16h, 0°C) a significant increase in chromosomal losses was reported.

Executive summary:

Benzonitrile did not induce chromosomal losses under standard conditions (16h, 30°C) up to 2190 µg/ml. Under modified test conditions (4h 30°C + 16h, 0°C) a significant increase in chromosomal losses was reported.

Reference 9

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1982

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

mouse lymphoma L5178Y cells

Additional strain / cell type characteristics:

other: TK+/-

Metabolic activation:

with and without

Metabolic activation system:

S9 (Arocol 1254 induced rat liver)

Test concentrations with justification for top dose:

0.5-1.07 µl/ml (without metabolic activation)
0.39-0.8 µl/ml (with metabolic activation)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

viability without metabolic activation: 71-11%; with: 104-39%

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

other: all strains/cell types tested

Conclusions:

Interpretation of results:
negative

Benzonitrile did not significantly increase the mutation rate in mouse lymphoma L5178Y cells up to cytotoxic concentrations.

Executive summary:

Benzonitrile did not significantly increase the mutation rate in mouse lymphoma L5178Y cells up to cytotoxic concentrations.

Reference 10

Endpoint:

in vitro DNA damage and/or repair study

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1988

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 479 (Genetic Toxicology: In Vitro Sister Chromatid Exchange Assay in Mammalian Cells)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

sister chromatid exchange assay in mammalian cells

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Metabolic activation system:

S9-mix from Arocol 1254 induced rat liver

Test concentrations with justification for top dose:

5 - 166.7 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 166.7 µg/ml

Remarks on result:

other: all strains/cell types tested

Conclusions:

Interpretation of results:
negative

Benzonitrile did not induce a significant increase of sister-chromatide exchange in CHO-cells up to cytotoxic concentrations.

Executive summary:

Benzonitrile did not induce a significant increase of sister-chromatide exchange in CHO-cells up to cytotoxic concentrations.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

One negative in vivo micronucleus test in mice (NTP, 1995) is available.

Based on the in vivo study Benzonitrile was not classified for genetic toxicity.

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2000

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

micronucleus assay

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Route of administration:

oral: gavage

Duration of treatment / exposure:

13 weeks (micronucleus test at the end of a 90 day study)

Frequency of treatment:

daily

Post exposure period:

no data

Dose / conc.:

600 mg/kg bw/day (nominal)

Remarks:

Basis: actual ingested

No. of animals per sex per dose:

9-10 males; 7-10 females

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

systemic toxicity at 37.5 mg/kg/d (females) and 75 mg/kg/d (males)

Vehicle controls validity:

not specified

Negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

Interpretation of results: negative
Benzonitrile did not increase the rate of micronuclei in polychromatic erythrocytes in a micronucleus test conducted at the end of a 90 day study in mice.

Executive summary:

At the end of a sub-chronic oral toxicity study in 7-10 B6C3F1-mice/sex/dose a micronucleus test was conducted. Exposure to benzonitrile did not increase the rate of micronuclei in polychromatic erythrocytes at doses up to 600 mg/kg/d. This micronucleus test conducted at the end of a 90 day study is valid according to OECD 474. Systemic adverse effects were reported at 37.5 mg/kg/d. Benzonitrile is considered to be not mutagenic in vivo.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vivo:

Benzonitrile did not induce an increase in bacterial reverse mutation (Microtest, 1988), a significantly increase in the mutation rate in mouse lymphoma L5178Y cells (Microbiological Associates, 1982) or a significant increase of sister-chromatide exchange in CHO-cells (NTP, 1988) up to cytotoxic concentrations.

Ambiguous results were reported in a Chromosome Aberration assay (NTP, 1988). In a first experiment with metabolic activation a total of 72% of the cell had chromosomal aberrations (64% basic, 8% complex) at 1495 µg/ml. In a second experiment with metabolic activation this severe effect could not be verified. The incubation at 1005 – 1993 µg/ml led to an increase in chromosomal aberration of up to 11% (3% basic, 9% complex). The DMSO control was 3, 1, and 2%. The highest concentration tested (1993 µg/ml) caused cytotoxicity. However, without additional data it cannot be verified that aberrations only occur at cytotoxic concentrations.

Ambiguous results were also reported in a chromosomal loss assay in S. cerevidiae (Whittaker, 1900). Under standard conditions (incubation for 16h at 30°C) benzoniotrile did not increase the rate of chromosomal losses. However, the use of modified conditions (incubation for 4h at 30°C followed by 16 h at 0°C) led to a significant increase of chromosomal losses. According to the authors this increase is caused by an interaction with the spindle apparatus. It is difficult to judge the significance of the effect observed under non-standard conditions.

In addition to in vitro data the results of an in vivo micronucleus test were reported (NTP, 1995, cited in BG Chemie 2000). This test was conducted at the end of a sub-chronic oral toxicity study in 7-10 B6C3F1-mice/sex/dose. Exposure to benzonitrile did not increase the rate of micronuclei in polychromatic erythrocytes at doses up to 600 mg/kg/d. This micronucleus test is valid according to OECD 474 because systemic adverse effects were already reported at 37.5 mg/kg/d. Benzonitrile is considered to be not mutagenic in vivo.

Justification for selection of genetic toxicity endpoint
in vivo study

Justification for classification or non-classification

Based on the available data it can be concluded that the potential genetic toxicity of benzonitrile is low. A classification is not warranted.