[μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')]hexafluorodiboron

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

A bacterial reverse mutation assay was carried out according to OECD guideline 471 using strains S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvr A. The results of the Bacterial Reverse Mutation Assay indicate that, under the conditions of this study, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron did not cause a positive mutagenic response with any of the tester strains in either the presence or absence of Aroclor-induced rat liver S9.

An In vitro mammalian cell gene mutation assay was carried out using Chinese hamster ovary cells according to OECD guideline 476. Under the conditions of the assay described in this report, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron was concluded to be negative for the induction of forward mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus (hprt) of Chinese hamster ovary (CHO) cells, in the presence and absence of an exogenous metabolic activation system, in the in vitro mammalian cell forward gene mutation (CHO/HPRT) assay.

In vitro Mammalian chromosomal aberration assay in Chinese hamster ovary cells was carried out according to OECD guideline 473. [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N’)] hexafluorodiboron was concluded to be negative for the induction of structural and numerical chromosomal aberrations in the non-activated and S9-activated test systems in the in vitro mammalian chromosomal aberration assay using CHO cells.

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:

31st August 2016 to 19th September 2016

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 reverse mutation assay

Specific details on test material used for the study:

Test Substance
Identification:
[μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron
Batch No.:
AEF0009100
Description:
Clear colorless liquid
Storage Conditions:
Room temperature, protected from light
Receipt Date:
12 July 2016

Species / strain / cell type:

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

Details on mammalian cell type (if applicable):

Tester strains TA98 and TA1537 are reverted from histidine dependence (auxotrophy) to histidine independence (prototrophy) by frameshift mutagens. Tester strain TA1535 is reverted by mutagens that cause basepair substitutions. Tester strain TA100 is reverted by mutagens that cause both frameshift and basepair substitution mutations. Specificity of the reversion mechanism in E. coli is sensitive to basepair substitution mutations, rather than frameshift mutations (Green and Muriel, 1976).
Salmonella tester strains were derived from Dr. Bruce Ames’ cultures; E. coli tester strains were from the National Collection of Industrial and Marine Bacteria, Aberdeen, Scotland.

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

Tester strains TA98 and TA1537 are reverted from histidine dependence (auxotrophy) to histidine independence (prototrophy) by frameshift mutagens. Tester strain TA1535 is reverted by mutagens that cause basepair substitutions. Tester strain TA100 is reverted by mutagens that cause both frameshift and basepair substitution mutations. Specificity of the reversion mechanism in E. coli is sensitive to basepair substitution mutations, rather than frameshift mutations (Green and Muriel, 1976).
Salmonella tester strains were derived from Dr. Bruce Ames’ cultures; E. coli tester strains were from the National Collection of Industrial and Marine Bacteria, Aberdeen, Scotland.

Metabolic activation:

with

Metabolic activation system:

Aroclor 1254-induced rat liver S9 was used as the metabolic activation system.

Vehicle / solvent:

Water was used as the vehicle.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-acetylaminofluorene

9-aminoacridine

2-nitrofluorene

sodium azide

methylmethanesulfonate

Details on test system and experimental conditions:

Tester strains TA98 and TA1537 are reverted from histidine dependence (auxotrophy) to histidine independence (prototrophy) by frameshift mutagens. Tester strain TA1535 is reverted by mutagens that cause basepair substitutions. Tester strain TA100 is reverted by mutagens that cause both frameshift and basepair substitution mutations. Specificity of the reversion mechanism in E. coli is sensitive to basepair substitution mutations, rather than frameshift mutations (Green and Muriel, 1976).

To confirm the sterility of the S9 and Sham mixes, a 0.5 mL aliquot of each was plated on selective agar. To confirm the sterility of the test substance and the vehicle, all test substance dose levels and the vehicle used in each assay were plated on selective agar with an aliquot volume equal to that used in the assay. These plates were incubated under the same conditions as the assay.
One-half (0.5) milliliter of S9 or Sham mix, 100 μL of tester strain (cells seeded) and 100 μL of vehicle or test substance dilution were added to 2.0 mL of molten selective top agar at 45±2°C. When plating the positive controls, the test substance aliquot was replaced by a 50.0 μL aliquot of appropriate positive control. After vortexing, the mixture was overlaid onto the surface of 25 mL of minimal bottom agar. After the overlay had solidified, the plates were inverted and incubated for 48 to 72 hours at 37±2°C. Plates that were not counted immediately following the incubation period were stored at 2-8°C until colony counting could be conducted.

Evaluation criteria:

Evaluation of Test Results
For each replicate plating, the mean and standard deviation of the number of revertants per plate were calculated and are reported.
For the test substance to be evaluated positive, it must cause a dose-related increase in the mean revertants per plate of at least one tester strain over a minimum of two increasing concentrations of test substance as specified below:
Strains TA1535 and TA1537
Data sets were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 3.0-times the mean vehicle control value.
Strains TA98, TA100 and WP2 uvrA
Data sets were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 2.0-times the mean vehicle control value.
An equivocal response is a biologically relevant increase in a revertant count that partially meets the criteria for evaluation as positive. This could be a dose-responsive increase that does not achieve the respective threshold cited above or a non-dose responsive increase that is equal to or greater than the respective threshold cited. A response was evaluated as negative if it was neither positive nor equivocal.

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

not applicable

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

All criteria for a valid study were met as described in the protocol. The results of the Bacterial Reverse Mutation Assay indicate that, under the conditions of this study, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron did not cause a positive mutagenic response with any of the tester strains in either the presence or absence of Aroclor-induced rat liver S9.

Executive summary:

The test substance, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron, was tested to evaluate its mutagenic potential by measuring its ability to induce reverse mutations at selected loci of several strains of Salmonella typhimurium and at the tryptophan locus of Escherichia coli strain WP2 uvrA in the presence and absence of an exogenous metabolic activation system. Water was used as the vehicle.

In the initial toxicity-mutation assay, the dose levels tested were 1.50, 5.00, 15.0, 50.0, 150, 500, 1500 and 5000 μg per plate. Neither precipitate nor toxicity was observed. No positive mutagenic responses were observed with any of the tester strains in either the presence or absence of S9 activation.

In the confirmatory mutagenicity assay, the dose levels tested were 15.0, 50.0, 150, 500, 1500 and 5000 μg per plate. Neither precipitate nor toxicity was observed. No positive mutagenic responses were observed with any of the tester strains in either the presence or absence of S9 activation.

These results indicate [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron was negative for the ability to induce reverse mutations at selected loci of several strains of Salmonella typhimurium and at the tryptophan locus of Escherichia coli strain WP2 uvrA in the presence and absence of an exogenous metabolic activation system.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18th November 2016 to 23 December 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

On day of dosing, expiration date of the positive control B(a)P was not checked. All cultures dosed with B(a)P behaved normally and validity criteria were met, indicating the B(a)P used had not lost it's effectiveness. Study Director determined no impact.

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell transformation assay

Specific details on test material used for the study:

The identity, strength, purity, stability and composition or other characteristics to define the test substance have not been determined.
All unused test substance were disposed prior to report finalization.

The vehicle used to deliver [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron to the test system was di-H2O.

Vehicle- diH2O
Supplier- Sigma-Aldrich
Lot Number(expiry)- RNBF2734(feb 2018) RNBD7780 (apr 2017)
Purity- sterile-filtered

Test substance dilutions were prepared immediately before use and delivered to the test system at room temperature under filtered light.

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

The test substance, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron, was evaluated for its ability to induce forward mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus (hprt) of Chinese hamster ovary (CHO) cells,

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced rat liver S9 was used as the metabolic activation system.

Test concentrations with justification for top dose:

the concentrations chosen for the definitive mutagenicity assay were 125, 250, 500, 1000, 1200, 1400, 1600, 1800 and 2000 μg/mL with S9 and 125, 250, 500, 1000, 1500 and 2000 μg/mL without S9.
A preliminary toxicity assay was used to decide concentrations chosen.

Vehicle / solvent:

Water (di-H2O) was used as the vehicle.

Untreated negative controls:

no

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

ethylmethanesulphonate

Details on test system and experimental conditions:

The CHO-K1-BH4 cell line is a proline auxotroph with a modal chromosome number of 20, a population doubling time of 12-14 hours, and a cloning efficiency generally greater than 80% (Li et al., 1987). The CHO-K1-BH4 cells used in this study were obtained from A.W. Hsie, Oak Ridge National Laboratories (Oak Ridge, TN).

Preparation of Target Cells
CHO cells were maintained in Ham's F12 medium supplemented with 3 mM L-glutamine and 5% (v/v) heat-inactivated and dialyzed fetal bovine serum (F12FCM5) under standard conditions (37 ± 1°C in a humidified atmosphere of 5 ± 1% CO2 in air). All media contained antimycotics and antibiotics.

To reduce the frequency of spontaneous HPRT- mutants prior to use in an assay, the cells were cleansed in medium supplemented with hypoxanthine, aminopterin and thymidine (HAT). Frozen stock cultures were tested to confirm the absence of mycoplasma contamination and for karyotpye stability. Cells used in the mutation assay did not exceed 15 passages from frozen stock.

Statistics:

Statistical analyses were performed using the method of Snee and Irr (1981), with significance established at the 0.05 level.
Once criteria for a valid assay were met, the responses observed in the assay were evaluated as follows.
The test substance was considered to have produced a positive response if it induced a dose-dependent increase in mutation frequency and an increase exceeding 95% historical vehicle control limits in at least one test dose level(s) as compared with concurrent vehicle control (p<0.01). If only one criterion was met (a statistically significant or dose-dependent increase or an increase exceeding the historical control 95% confidence interval), the result were considered equivocal. If none of these criteria were met, the results were considered to be negative.
Other criteria also may be used in reaching a conclusion about the study results (e.g., comparison to historical control values, biological significance, etc.). In such cases, the Study Director used sound scientific judgment and clearly reported and described any such considerations.

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

Under the conditions of the assay described in this report, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron was concluded to be negative for the induction of forward mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus (hprt) of Chinese hamster ovary (CHO) cells, in the presence and absence of an exogenous metabolic activation system, in the in vitro mammalian cell forward gene mutation (CHO/HPRT) assay.

Executive summary:

The test substance, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron, was evaluated for its ability to induce forward mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus (hprt) of Chinese hamster ovary (CHO) cells, in the presence and absence of an exogenous metabolic activation system, as assayed by colony growth in the presence of 6-thioguanine (TG resistance, TGr). Water (di-H2O) was used as the vehicle.

In the preliminary toxicity assay, the concentrations tested were 3.91, 7.81, 15.6, 31.3, 62.5, 125, 250, 500, 1000 and 2000 μg/mL. The maximum concentration evaluated approximated the limit dose for this assay. No visible precipitate was observed at the beginning or end of treatment. Adjusted relative survival was 75.70 and 24.75% at a concentration of 1000 and 2000 μg/mL with and without S9, respectively. Adjusted relative survival was approximated 0% at all higher concentrations with S9. Based upon these results, the concentrations chosen for the definitive mutagenicity assay were 125, 250, 500, 1000, 1200, 1400, 1600, 1800 and 2000 μg/mL with S9 and 125, 250, 500, 1000, 1500 and 2000 μg/mL without S9.

In the definitive mutagenicity assay, no visible precipitate was observed at the beginning or end of treatment. The average adjusted relative survival was 22.54 and 44.15% at a concentration of 2000 μg/mL with and without S9, respectively. Cultures treated at concentrations of 125, 250, 500, 1000 and 2000 μg/mL with and without S9 were chosen for mutant selection. No significant increases in mutant frequency, as compared to the concurrent vehicle controls, were observed at any concentration evaluated with or without S9 (p > 0.01). The positive controls induced significant increases in mutant frequency (p < 0.01).

These results indicate [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N')] hexafluorodiboron was negative for the ability to induce forward mutations at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus (hprt) of Chinese hamster ovary (CHO) cells, in the presence and absence of an exogenous metabolic activation system.

Reference 3

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16th August 2016 to 23rd September 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

other: In vitro Mammalian Chromosomal Aberration Assay

Specific details on test material used for the study:

The identity, strength, purity, stability, and composition, or other characteristics to define the test substance have not been determined.

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

Chinese hamster ovary (CHO-K1) cells (repository number CCL 61) were obtained from American Type Culture Collection, Manassas, VA. In order to assure the karyotypic stability of the cell line, working cell stocks were not used beyond passage 15. The frozen lot of cells was tested using the Hoechst staining procedure and found to be free of mycoplasma contamination. This cell line has an average cell cycle time of 10-14 hours with a modal chromosome number of 20. The use of CHO cells has been demonstrated to be an effective method of detection of chemical clastogens (Preston et al., 1981).

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced rat liver S9 was used as the metabolic activation system.

Test concentrations with justification for top dose:

Based on the results of the preliminary toxicity test, the doses selected for testing in the chromosomal aberration assay were as follows:
Non-activated:
4 hour treatment, 16 hour recovery:
500, 1000, 1500, 1800, 2000
20 hour treatment, 0 hour recovery:
100, 200, 250, 300, 350, 400, 450, 500, 550

S9 Activated:
4 hour treatment, 16 hour recovery:
5, 10, 15, 20, 25, 30 , 40, 50, 60

Precipitation of the test substance dosing solution in the treatment medium was determined using unaided eye at the beginning and conclusion of treatment. The highest dose evaluated for the chromosomal aberrations was selected based on the following:
4 hour (-S9)
55± 5% cytotoxicity (cell growth inhibition relative to the vehicle control)

4 hour (+S9)
55 ± 5% cytotoxicity (cell growth inhibition relative to the vehicle control)

20 hour (-S9)
55 ± 5% cytotoxicity (cell growth inhibition relative to the vehicle control)

Vehicle / solvent:

Water was used as the vehicle based on the solubility of the test substance, and compatibility with the target cells.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

mitomycin C

other: Sterile Water

Details on test system and experimental conditions:

Test System
Chinese hamster ovary (CHO-K1) cells (repository number CCL 61) were obtained from American Type Culture Collection, Manassas, VA. In order to assure the karyotypic stability of the cell line, working cell stocks were not used beyond passage 15. The frozen lot of cells was tested using the Hoechst staining procedure and found to be free of mycoplasma contamination. This cell line has an average cell cycle time of 10-14 hours with a modal chromosome number of 20. The use of CHO cells has been demonstrated to be an effective method of detection of chemical clastogens (Preston et al., 1981).
Solubility Determination
Water was used as the vehicle based on the solubility of the test substance, and compatibility with the target cells. In a solubility test conducted at BioReliance, the test substance was soluble in water at a concentration of approximately 50 mg/mL, the maximum concentration tested for solubility.
Preparation of Target Cells
Exponentially growing CHO-K1 cells were seeded in complete medium (McCoy's 5A medium containing 10% fetal bovine serum, 1.5 mM L-glutamine, 100 units/mL penicillin, 100 μg/mL streptomycin and 2.5 μg/mL Amphotericin B) for each treatment condition at a target of 5 x 105 cells/culture. The cultures were incubated under standard conditions (37 ± 1°C in a humidified atmosphere of 5 ± 1% CO2 in air) for 16-24 hours.

Rationale for test conditions:

The number and types of aberrations (structural and numerical) found, the percentage of structurally damaged cells in the total population of cells examined (percent aberrant cells), the percentage of numerically damaged cells in the total population of cells examined, and the average number of structural aberrations per cell (mean aberrations per cell) were calculated and reported for each treatment group. Chromatid and isochromatid gaps were presented in the data but were not included in the total percentage of cells with one or more aberrations or in the average number of aberrations per cell.

Evaluation criteria:

The test substance was considered to have induced a positive response if
• at least one of the test concentrations exhibits a statistically significant increase when compared with the concurrent negative control (p ≤ 0.05), and
• the increase is concentration-related (p ≤ 0.05), and
• results are outside the 95% control limit of the historical negative control data.
The test substance was considered to have induced a clear negative response if none of the criteria for a positive response were met.

Statistics:

Statistical analysis was performed using the Fisher's exact test (p ≤ 0.05) for a pairwise comparison of the frequency of aberrant cells in each treatment group with that of the vehicle control. The Cochran-Armitage trend test was used to assess dose-responsiveness.

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

[μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N’)] hexafluorodiboron was concluded to be negative for the induction of structural and numerical chromosomal aberrations in the non-activated and S9-activated test systems in the in vitro mammalian chromosomal aberration assay using CHO cells.

Executive summary:

The test substance, [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N’)] hexafluorodiboron, was tested to evaluate the potential to induce structural chromosomal aberrations using Chinese hamster ovary (CHO) cells in both the absence and presence of an of an exogenous metabolic activation system. CHO cells were treated for 4 hours in the absence and presence of S9, and for 20 hours in the absence of S9. Water was used as the vehicle.

In the preliminary toxicity assay, the doses tested ranged from 0.2 to 2000 μg/mL, which was the limit dose for this assay. Cytotoxicity (≥ 50% reduction in cell growth index relative to the vehicle control) was observed at 2000 μg/mL in the non-activated 4-hour exposure group; at doses ≥ 60 in the S9-activated 4-hour exposure group; and at doses ≥ 600 μg/mL in the non-activated 20-hour exposure group. Based upon these results, the doses chosen for the chromosomal aberration assay ranged from 500 to 2000 μg/mL for the non-activated 4-hour exposure group; from 5 to 60 μg/mL for the S9-activated 4-hour exposure group; and from 100 to 550 μg/mL for the non-activated 20-hour exposure group.

In the chromosomal aberration assay, cytotoxicity (55 ± 5% reduction in cell growth index relative to the vehicle control) was observed at doses ≥ 1500 μg/mL in the non-activated 4-hour exposure group; at doses ≥ 20 μg/mL in the S9-activated 4-hour exposure group; and at doses ≥ 350 μg/mL in the non-activated 20-hour exposure group. The doses selected for evaluation of chromosomal aberrations were 500, 1000, and 1500 μg/mL for the non-activated 4-hour exposure group; 10, 15, and 20 μg/mL for the S9-activated 4-hour exposure group; and 100, 200, and 350 μg/mL for the non-activated 20-hour exposure group.

In the non-activated 4-hour exposure group, statistically significant increases (2.3% and 1.7%) in structural aberrations was observed at doses 1000 and 1500 μg/mL, respectively (p ≤ 0.05 or p ≤ 0.01; Fisher’s Exact test). Statistically significant increases (3.0% and 3.7%) in numerical aberrations was also observed at doses 1000 and 1500 μg/mL, respectively (p ≤ 0.05 or p ≤ 0.01; Fisher’s Exact test). However, the Cochran-Armitage test was negative for a dose response (p > 0.05) for structural and numerical chromosomal aberrations. In addition, the increases in structural and numerical chromosomal aberrations were within their respective historical 95% control limits. The statistically significant induction was most likely due to low background aberration in concurrent solvent controls. Therefore, the statistically significant increases were considered to be biologically irrelevant.

In the S9-activated 4-hour exposure group, no significant or dose-dependent increases in structural aberrations were observed at any dose (p > 0.05; Fisher’s Exact and Cochran-Armitage tests). A statistically significant increase (4.0%) in numerical aberrations was observed at 10 μg/mL (p ≤ 0.01; Fisher’s Exact test). However, the Cochran-Armitage test was negative for a dose response (p > 0.05). In addition, the increase in numerical chromosome aberrations was within the historical 95% control limit. Therefore, the statistically significant increase was considered to be biologically irrelevant.

In the non-activated 20-hour exposure group, no significant or dose-dependent increases in structural or numerical aberrations were observed at any dose (p > 0.05; Fisher’s Exact and Cochran-Armitage tests).

These results indicate that [μ-(5-amino-1,3,3-trimethylcyclohexylamine-N:N’)] hexafluorodiboron was negative for the induction of structural and numerical chromosomal aberrations in the presence and absence of the exogenous metabolic activation system.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)