Diisopropylbenzene hydroperoxide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Three in vitro tests are available and did not show any in vitro genotoxic potential.

Ames test

The potential of diisopropylbenzene monohydroperoxide in diisopropylbenzene (peroxide content around 50%) to induce reverse mutation in Salmonella typhimurium (strains: TA 1535, TA 1537, TA 1538, TA 100 and TA 102) was evaluated according to the method of Ames (1976) and in compliance with the GLP (Van Ginkel, 1982). A preliminary test was carried out to assess the chemical toxicity of the test substance for the bacteria. For the main test, the following concentrations were used: 0, 0.37, 1.11, 3.33, 10 and 30 µg/plate. The incorporation of the test substance in the medium containing the bacteria did not increase the numbers of his+ revertants with any of the five tester strains, either in the absence or in the presence of the S-9 mix. At the highest dose levels the test substance was clearly toxic for the bacteria (especially in the absence of the S-9 mix) but at lower levels the background lawn of bacterial growth in control and test plates was comparable.

 

Mouse lymphoma assay

The potential of the test item (diisopropylbenzene monohydroperoxide in diisopropylbenzen, peroxide content: 50.9 %) to induce mutations was evaluated in a mouse lymphoma assay, OECD 476 and GLP compliant (Sarlang, 2012). After a preliminary toxicity test, the test item was tested in three independent experiments, with and/or without a metabolic activation system (S9 mix).

Since the test item was found severely cytotoxic in the preliminary test, the choice of the highest dose-level for the main test was based on the decrease in Adj. RTG.

The selected dose-levels for experiments without S9 were: 1.6, 3.1, 6.3, 12.5, 25 and 50 µg/mL for the first experiment (3-hour treatment), and 0.6, 1.3, 2.5, 5, 10, 15 and 20 µg/mL for the second experiment (24-hour treatment). Following the 3-hour treatment, a marked toxicity was induced at 50 µg/mL, as shown by a 66% decrease in Adj. RTG (Adjusted Relative Total Growth). Following the 24-hour treatment, a moderate to severe toxicity was induced at dose-levels = 10 µg/mL, as shown by a 43 to 97% decrease in Adj. RTG.

The selected dose-levels for experiments with S9 were as follows: 6.3, 12.5, 25, 50, 100 and 200 µg/mL for the first experiment, 12.5, 25, 50, 100, 150 and 200 µg/mL for the second experiment, and 25, 50, 75, 100, 116.7, 133.3 and 150 µg/mL for the third experiment. Following the first experiment, a slight to severe toxicity was induced at dose-levels = 50 µg/mL, as shown by a 31 to 100% decrease in Adj. RTG. Following the second experiment, a marked to severe toxicity was induced at dose-levels = 100 µg/mL, as shown by a 66 to 97% decrease in Adj. RTG. Following the third experiment, a moderate to severe toxicity was induced at dose-levels = 75 µg/mL, as shown by a 48 to 98% decrease in Adj. RTG.

No noteworthy increases in the mutation frequency, which could be considered as biologically relevant, were induced in any of the experiments, neither in the absence nor in the presence of S9.

In conclusion the test item did not show any mutagenic activity in the mouse lymphoma assay, in the presence or in the absence of a rat metabolizing system.

 

In vitro micronucleus assay:

The potential of the test item to induce an increase in the frequency of micronucleated cells in L5178Y TK+/-mouse lymphoma cells was evaluated in an in vitro micronucleus test performed according to the OECD 487 guideline (Sarlang, 2012).The selection of the highest dose-level was based oncytotoxicity. 

Experiments without S9 mix:

In the first experiment (3 h treatment + 24 h recovery) the following doses were used: 0.3, 0.6, 1.3, 2.5, 5, 7.5, 10 and 20 µg/mL. A severe toxicity was noted at dose-levels = 10 µg/mL, as shown by a 85 to 100% decrease in the PD. In the second experiment (24 h treatment + 20 h recovery), the following doses were used: 5, 7, 9, 11, 13, 15, 17 and 21 µg/mL. A slight to severe toxicity was noted at dose-levels = 13 µg/mL, as shown by a 36 to 100% decrease in the PD.

No significant increase in the frequency of micronucleated cells was noted after the 3- and 24-hour treatments without S9. The recommended level of toxicity (decrease of 55 ± 5% in PD) was not reached in any of these experiments. But, since the spacing used between each dose-level tested in these experiments was particularly narrow, no complementary experiment was needed and the results obtained were sufficient to conclude on the absence of potential of the test item to induce increase in the frequency of micronucleated cells.

Experiments with S9 mix:

In the first experiment (24 h treatment + 24 h recovery) the following doses were used:  5, 10, 20, 30, 33, 36, 38 and 40 µg/mL in the first experiment. A slight to severe toxicity was noted at dose-levels >= 36 µg/mL without any clear evidence of a dose-response relationship, as shown by a 39 to 100% decrease in the PD. In the second experiment (3 h treatment + 24 h recovery) the following doses were used: 10, 20, 25, 30, 33, 36, 38 and 40 µg/mL in the second experiment. A slight to severe toxicity was noted at dose-levels >= 20 µg/mL as shown by a 38 to 100% decrease in the PD

In the first experiment, no significant increase in the frequency of micronucleated cells was noted. In the second experiment, slight increases in the frequency of micronucleated cells were observed at all analyzed dose-levels. These increases exceeded the threshold of 2.5-fold the vehicle control value (up to 6.0-fold at 10 µg/mL). However, these increases were neither statistically significant, nor dose-related nor reproducible since no increase in the frequency of micronucleated cells were observed in the first experiment performed under the same experimental conditions. Moreover, the corresponding frequencies remained within the historical data range of the vehicle. Consequently, these increases did not meet the criteria for a positive response and were considered as non-biologically relevant.

In conclusion, Luperox DH did not induce any chromosome damage, or damage to the cell division apparatus, in cultured mammalian somatic cells, using L5178Y TK+/- mouse lymphoma cells, either in the presence or in the absence of S9mix.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 June 2012 - 02 October 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Compliant to GLP and testing guidelines; adequate consistence between data, comments and conclusions.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine Kinase

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: RPMI 1640 medium containing L-Glutamine (2 mM), penicillin (100 U/mL), streptomycin (100 µg/mL) and sodium
pyruvate (200 µg/mL)
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

rat liver S9 mix

Test concentrations with justification for top dose:

Experiments without S9 mix
Using a treatment volume of 1% in culture medium, the selected dose-levels were:
- 1.6, 3.1, 6.3, 12.5, 25 and 50 µg/mL for the first experiment (3-hour treatment),
- 0.6, 1.3, 2.5, 5, 10, 15 and 20 µg/mL for the second experiment (24-hour treatment).

Experiments without S9 mix
Using a treatment volume of 1% in culture medium, the selected dose-levels were:
- 1.6, 3.1, 6.3, 12.5, 25 and 50 µg/mL for the first experiment (3-hour treatment),
- 0.6, 1.3, 2.5, 5, 10, 15 and 20 µg/mL for the second experiment (24-hour treatment).

Vehicle / solvent:

Vehicle used: dimethylsulfoxide
Justification for choice: test item was soluble in the vehicle at:
- 860 mg/mL for the preliminary toxicity test,
- 20 mg/mL for the first experiment and for the second experiment with S9 mix,
- 15 mg/mL for the second experiment without S9 mix and the third experiment.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: methylmethanesulfonate (-S9 mix); cyclophosphamide (+S9 mix)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 3 and 24 hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): 11-12 days

SELECTION AGENT (mutation assays): trifluorothymidine

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency; relative total growth.

Evaluation criteria:

IWGT recommendations were followed for the determination of a positive result, which should fulfill the following criteria:
- at least at one dose-level the mutation frequency minus the mutation frequency of the vehicle control (IMF) equals or exceeds the Global Evaluation Factor (GEF) of 126 x 10-6,
- a dose-related trend is demonstrated by a statistically significant trend test.

Unless an effect is considered as clearly positive, the reproducibility of a positive effect should be confirmed.

Noteworthy increases in the mutation frequency observed only at high levels of cytotoxicity (Adj. RTG lower than 10%), but with no evidence of mutagenicity at dose-levels with Adj. RTG between 10 and 20%, are not considered as positive results.

A test item may be considered as non-mutagenic when there is no culture showing an Adj. RTG value between 10 and 20% if (Moore et al., 2002):
- there is at least one negative data point between 20 and 25% Adj. RTG and no evidence of mutagenicity in a series of data points between 100 and 20% Adj. RTG,
- there is no evidence of mutagenicity in a series of data points between 100 and 25% and there is also a negative data point between 10 and 1% Adj. RTG.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: strain/cell type: mouse lymphoma L5178Y cells

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

The test item was not mutagenic to mammalian cells in the presence or absence of metabolic activation.

Executive summary:

The potential of the test item (diisopropylbenzene monohydroperoxide in diisopropylbenzen) was evaluated in a Mouse Lymphoma Assay. The study was performed according to international guidelines (OECD guideline No. 476 and Council Regulation (EC) No. 440/2008 of 30 May 2008, Annex, Part B.17) and in compliance with the principles of Good Laboratory Practice.

 

Methods

After a preliminary toxicity test, Diisopropylbenzene monohydroperoxide, was tested in three independent experiments, with and/or without a metabolic activation system (S9 mix) prepared from a liver microsomal fraction (S9 fraction) of rats induced with Aroclor 1254.

Cultures of 20 mL at 5 x 10⁵cells/mL (3-hour treatment) or cultures of 50 mL at 2 x 10⁵cells/mL (24-hour treatment) were exposed to the test or control items, in the presence or absence of S9 mix (final concentration of S9 fraction 2%). During the treatment period, the cells were maintained as suspension culture in RPMI 1640 culture medium supplemented by heat inactivated horse serum at 5% (3-hour treatment) or 10% (24-hour treatment) in a 37°C, 5% CO₂humidified incubator. For the 24-hour treatment, flasks were gently shaken at least once.

 

Cytotoxicity was measured by assessment of Adjusted Relative Total Growth (Adj. RTG), Adjusted Relative Suspension Growth (Adj. RSG) and Cloning Efficiency following the expression time (CE₂).

The number of mutant clones (differentiating small and large colonies) was evaluated after expression of the mutant phenotype.

 

The test item was dissolved in dimethylsulfoxide (DMSO).

 

Results

With one exception which is not considered to have a biological impact on the validity of the study, the Cloning Efficiencies (CE₂), the Suspension Growths (SG) and the mutation frequencies of the vehicle controls were as specified in the acceptance criteria. Moreover, the induced mutation frequencies obtained for the positive controls met the acceptance criteria specified in the study plan. The study was therefore considered as valid.

 

Since the test item was found severely cytotoxic in the preliminary test, the choice of the highest dose-level for the main test was based on the level of toxicity, according to the criteria specified in the international guidelines (decrease in Adj. RTG).

 

Experiments without S9 mix

Using a treatment volume of 1% in culture medium, the selected dose-levels were:

- 1.6, 3.1, 6.3, 12.5, 25 and 50 µg/mL for the first experiment (3-hour treatment),

- 0.6, 1.3, 2.5, 5, 10, 15 and 20 µg/mL for the second experiment (24-hour treatment).

 

Cytotoxicity

Following the 3-hour treatment, a marked toxicity was induced at 50 µg/mL, as shown by a 66% decrease in Adj. RTG.

Following the 24-hour treatment, a moderate to severe toxicity was induced at dose-levels = 10 µg/mL, as shown by a 43 to 97% decrease in Adj. RTG.

Mutagenicity

Following the 3- or 24-hour treatments, no relevant or dose-related increases in the mutation frequency were noted in comparison to the vehicle control. The results did not meet the criteria for a positive response.

 

Experiments with S9 mix

Using a treatment volume of 1% in culture medium, the selected dose-levels were as follows:

- 6.3, 12.5, 25, 50, 100 and 200 µg/mL for the first experiment,

- 12.5, 25, 50, 100, 150 and 200 µg/mL for the second experiment,

- 25, 50, 75, 100, 116.7, 133.3 and 150 µg/mL for the third experiment.

 

Cytotoxicity

Following the first experiment, a slight to severe toxicity was induced at dose-levels = 50 µg/mL, as shown by a 31 to 100% decrease in Adj. RTG.

Following the second experiment, a marked to severe toxicity was induced at dose-levels = 100 µg/mL, as shown by a 66 to 97% decrease in Adj. RTG. Following the third experiment, a moderate to severe toxicity was induced at dose-levels = 75 µg/mL, as shown by a 48 to 98% decrease in Adj. RTG.

 

Mutagenicity

No noteworthy increases in the mutation frequency, which could be considered as biologically relevant, were induced in any of the experiments.

 

Conclusion

The test item did not show any mutagenic activity in the mouse lymphoma assay, in the presence or in the absence of a rat metabolizing system.

Reference 2

Endpoint:

in vitro cytogenicity / micronucleus study

Remarks:

Type of genotoxicity: other: chromosome aberration and aneuploidy

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 October 2012 - 06 December 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Compliant to GLP and testing guidelines; adequate consistence between data, comments and conclusions.

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 487 (In vitro micronucleus)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell micronucleus test

Target gene:

Not applicable (not a gene mutation assay).

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: cryoprotective medium
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

rat liver S9 mix

Test concentrations with justification for top dose:

Without S9 mix:
- 0.3, 0.6, 1.3, 2.5, 5, 7.5, 10 and 20 µg/mL in the first experiment (3 h treatment + 24 h recovery),
- 5, 7, 9, 11, 13, 15, 17 and 21 µg/mL in the second experiment (24 h treatment + 20 h recovery).

With S9 mix:
- 5, 10, 20, 30, 33, 36, 38 and 40 µg/mL in the first experiment,
- 10, 20, 25, 30, 33, 36, 38 and 40 µg/mL in the second experiment.

Vehicle / solvent:

- Vehicle used: dimethylsulfoxide
- Justification for choice: the test item was dissolved in the vehicle at concentrations of:
Based on available solubility data, the test item is freely soluble in DMSO at 500 mg/mL. Therefore, using a test item concentration at 500 mg/mL and a treatment volume of 1% in culture medium, the highest recommended dose-level of 5000 µg/mL was achievable.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: mitomycin C, colchicine (-S9 mix); cyclophosphamide (+S9 mix)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION

First experiment Without S9 mix: 3 h treatment + 24 h recovery
First experiment With S9 mix: 3 h treatment + 24 h recovery

Second experiment Without S9 mix: 24 h treatment + 20 h recovery
Second experiment With S9 mix: 3 h treatment + 24 h recovery


NUMBER OF CELLS EVALUATED: 2000/dose

DETERMINATION OF CYTOTOXICITY
- Method: population doubling

Evaluation criteria:

The biological relevance of the results should be considered first. Statistical methods are used as an aid in evaluating the test results but should not be the only determinant of a positive response. A result is considered as positive if at least a 2.5-fold increase in the number of micronucleated cells in comparison to the concurrent control is observed, with a statistically significant difference, at one or more concentrations. Concentration-related increases in the frequency of micronucleated cells and comparison to the vehicle control historical data will also be taken into account.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

The test item did not induce any chromosome damage, or damage to the cell division apparatus, in cultured mammalian somatic cells, using L5178Y TK+/- mouse lymphoma cells, either in the presence or in the absence of a rat metabolizing system.

Executive summary:

 

	First experiment	Second experiment
Without S9 mix	3 h treatment + 24 h recovery	24 h treatment + 20 h recovery
With S9 mix	3 h treatment + 24 h recovery	3 h treatment + 24 h recovery

 

Each treatment was coupled to an assessment of cytotoxicity at the same dose-levels. Cytotoxicity was evaluated by determining the PD (Population Doubling) of cells and quality of the cells on the slides has also been taken into account.

 

The test item was dissolved in dimethylsulfoxide (DMSO).

 

Results

The population doublings and the mean frequencies of micronucleated cells for the vehicle controls were as specified in the acceptance criteria. Positive controls showed clear statistically significant increases in the frequency of micronucleated cells. The study was therefore considered to be valid.

 

Since the test item was found severely cytotoxic during the preliminary tests, the selection of the highest dose-level to be used in the main experiments was based on the level of toxicity, according to the criteria specified in the international regulations.

 

Experiments without S9 mix

With a treatment volume of 1% (v/v) in culture medium, the dose-levels used for treatments were:

.           0.3, 0.6, 1.3, 2.5, 5, 7.5, 10 and 20 µg/mL in the first experiment (3 h treatment + 24 h recovery),

.           5, 7, 9, 11, 13, 15, 17 and 21 µg/mL in the second experiment (24 h treatment + 20 h recovery).

 

At the end of the treatment periods, no precipitate or emulsion was observed in the culture medium at any of the tested dose-levels.

 

Cytotoxicity

Following the 3-hour treatment, a severe toxicity was noted at dose-levels = 10 µg/mL, as shown by a 85 to 100% decrease in the PD.

Following the 24-hour treatment, a slight to severe toxicity was noted at dose-levels = 13 µg/mL, as shown by a 36 to 100% decrease in the PD.

Micronucleus analysis

The dose-levels selected for micronucleus analysis were as follows:

.           2.5, 5 and 7.5 µg/mL for the 3-hour treatment, the latter inducing 13% decrease in the PD, and higher dose-levels being too cytotoxic,

.           9, 11 and 13 µg/mL for the 24-hour treatment, the latter inducing 36% decrease in the PD, and higher dose-levels being too cytotoxic.

 

No significant increase in the frequency of micronucleated cells was noted after the 3- and 24-hour treatments. The recommended level of toxicity (decrease of 55 ± 5% in PD) was not reached in any of these experiments. But, since the spacing used between each dose-level tested in these experiments was particularly narrow, no complementary experiment was needed and the results obtained were sufficient to conclude on the absence of potential of the test item to induce increase in the frequency of micronucleated cells.

 

Experiments with S9 mix

With a treatment volume of 1% (v/v) in culture medium, the dose-levels used for treatment were as follows:

.           5, 10, 20, 30, 33, 36, 38 and 40 µg/mL in the first experiment,

.           10, 20, 25, 30, 33, 36, 38 and 40 µg/mL in the second experiment.

 

Cytotoxicity

In the first experiment, a slight to severe toxicity was noted at dose-levels >= 36 µg/mL without any clear evidence of a dose-response relationship, as shown by a 39 to 100% decrease in the PD.

In the second experiment, a slight to severe toxicity was noted at dose-levels >= 20 µg/mL as shown by a 38 to 100% decrease in the PD.

 

Micronucleus analysis

The dose-levels selected for micronucleus analysis were as follows:

.           30, 33 and 38 µg/mL for the first experiment, the latter inducing a 39% decrease in the PD, and higher dose-level being too cytotoxic,

.           10, 20 and 25 µg/mL for the second experiment, the latter inducing a recommended 50% decrease in the PD.

 

In the first experiment, no significant increase in the frequency of micronucleated cells was noted.

In the second experiment, slight increases in the frequency of micronucleated cells were observed at all analyzed dose-levels. These increases exceeded the threshold of 2.5-fold the vehicle control value (up to 6.0-fold at 10 µg/mL). However, these increases were neither statistically significant, nor dose-related nor reproducible since no increase in the frequency of micronucleated cells were observed in the first experiment performed under the same experimental conditions.Moreover, the corresponding frequencies remained within the historical data range of the vehicle control (up to 3‰ versus [0.5 -5‰] for the historical values of the vehicle control). Consequently, these increases did not meet the criteria for a positive response and were considered as non-biologically relevant.

 

Conclusion

The test item did not induce any chromosome damage, or damage to the cell division apparatus, in cultured mammalian somatic cells, using L5178Y TK+/- mouse lymphoma cells, either in the presence or in the absence of a rat metabolizing system.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with recognized standard methods, GLP. Raw data are not available.

Qualifier:

no guideline available

Principles of method if other than guideline:

Ames B.N., J.McCann, and E.Yamasaki. Method for detecting carcinogens and mutagens with the Salmonella/mammalian microsome mutagenicity test, Mutation Research 31 (1975), 347-365

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial gene mutation assay

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

Aroc1or-induced rats

Test concentrations with justification for top dose:

0; 0.37; 1.1; 3.33; 10 and 30 µg/plate

Vehicle / solvent:

Ethanol

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

other: Sodium Azide, for strains TA 1535 and TA 100 without S-9 mix, hycanthone methanesulphonate for strains TA 1537, TA 1538 and TA 98 without S-9 mix, 2-aminoanthracene for all strains in the presence of S-9 mix.

Details on test system and experimental conditions:

The histidine requiring typhimurium mutants TA 1535, TA 1537, TA 1538, TA 98 and TA 100 to be used in the test have been provided
by Dr B.N. Ames, Berkeley, California, USA.

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at the highest concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

At the highest dose levels the test item was clearly toxic for the bacteria, (especially in the absence of the S-9 mix) but at lower levels the background lawn of bacterial growth in control and test plates was comparable.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

The results of preliminary test and main test are attached hereafter.

Conclusions:

Interpretation of results (migrated information):
negative

Incorporation of the test substance with the bacteria did not increase the numbers of his+ revertants with any of the five tester strains, either in the absence or in the presence of the S-9 mix.

Executive summary:

The potential of diisopropylbenzene monohydroperoxide (Purity: 49 -51 %) to induce reverse mutation inSalmonella typhimurium (strains: TA 1535, TA 1537, TA 1538, TA 100 and TA 102) was according to the method of Ames (1976) and in compliance with the Principles of Good Laboratory Practice.

A preliminary test was carried out to assess the chemical toxicity of the test substance for the bacteria. For the main test, the following concentrations were used: 0, 0.37, 1.11, 3.33, 10 and 30 µg/plate.

It appeared that incorporation of the test substance with the bacteria did not increase the numbers of his+ revertants with any of the five tester strains, either in the absence or in the presence of the S-9

mix.

 

At the highest dose levels the test substancve was clearly toxic for the bacteria, (especially in the absence of the S-9 mix) but at lower levels the background lawn of bacterial growth in control and test plates was comparable.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to EU regulation (EC) No 1272/2008, diisopropylbenzene monohydroperoxide in diisopropylbenze is not classified for genotoxicity.