Bis(α,α-dimethylbenzyl) peroxide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2000

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

& OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)

Principles of method if other than guideline:

Guidelines for Screening Mutagenicity Testing of Chemicals (Chemical Substances Control Law of Japan)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Bis(α,α-dimethylbenzyl) peroxide

EC Number:

201-279-3

EC Name:

Bis(α,α-dimethylbenzyl) peroxide

Cas Number:

80-43-3

Molecular formula:

C18H22O2

IUPAC Name:

1,1'-(dioxydipropane-2,2-diyl)dibenzene

Details on test material:

- Name of test material (as cited in study report): dicumyl peroxide
- Molecular formula (if other than submission substance): C18H22O2
- Substance type: white solid (flake form)
- Physical state: solid
- Analytical purity: 99.9%
- Lot/batch No.: 8X04
- Stability under test conditions: stable at normal temperature

Method

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S9 mix from rat liver, induced with phenobarbital and 5,6-benzoflavon

Test concentrations with justification for top dose:

cytotoxicity: 50, 150, 500, 1500, 5000 µg/plate
mutagenicity: 313, 625, 1250, 2500, 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Dimethyl sulfoxide

Controls

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: -S9 mix; 2-(2-Furyl)-3-(5-nitro-2-furyl)acrylamide (TA100, TA98, WP2 uvrA), Sodium azide (TA1535) and 9-Aminoacridine (TA1537) +S9 mix; 2-Aminoanthracene (five strains)

Details on test system and experimental conditions:

Pre-incubation method

Evaluation criteria:

The results were judged to be positive when the mean number of revertant colonies for each dose of the test article was increased twice or more than that in the negative control and when dose dependency or reproducibility was observed in the increase of revertant colonies, in at least one strain out of the five strains used with or without S9 mix.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

True negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

The number of revertant colonies was not increased twice or more than that in the negative control in any strain used with or without S9 mix in the two mutagenicity tests. In all tests, microbial contamination was not detected in the dosing formulation of the highest concentration or S9 mix. Furthermore, positive results were confirmed in the positive control groups, and the mean numbers of revertant colonies in the positive and negative controls were within the fluctuation range (mean ± 3 S.D.) of the historical control values in all strains. Thus, the validity of this test system was confirmed.

Any other information on results incl. tables

Table 1: Mutagenicity of dicumyl peroxide in bacteria (I)

				No colonies/plate
+/- S9mix	DCP (µg/plate)	TA100	TA1535	WP2 uvrA	TA98	TA1537
-	0	163 ± 2.1	12 ± 1.5	19 ± 4.7	27 ± 4.0	12 ± 4.0
-	313	158 ± 15.6	9 ± 1.7	25 ± 5.1	21 ± 4.2	10 ± 3.2
-	625	131 ± 9.2	20 ± 2.0	20 ± 2.0	15 ± 1.0	9 ± 4.9
-	1250	157 ± 20.0	18 ± 2.0	18 ± 2.0	18+-4.5	7+-1.5
-	2500	156 ± 8.0	21 ± 5.5	21 ± 5.5	17 ± 3.8	5 ± 0.6
-	5000	152 ± 18.0	23 ± 3.6	23 ± 3.6	24 ± 0.6	6 ± 2.3
+	0	154 ± 8.3	24 ± 8.4	24 ± 8.4	33 ± 4.4	16 ± 2.5
+	313	164 ± 2.9	27 ± 4.0	27 ± 4.0	35 ± 8.7	15 ± 1.0
+	625	173 ± 7.0	29 ± 5.2	29 ± 5.2	20 ± 1.0	13 ± 0.6
+	1250	141 ± 5.8	23 ± 7.4	23 ± 7.4	21 ± 3.0	11 ± 3.1
+	2500	135 ± 21.6	24 ± 8.3	24 ± 8.3	28 ± 2.9	13 ± 1.5
+	5000	143 ± 14.5	23 ± 4.6	23 ± 4.6	22 ± 5.9	10 ± 4.7
	Chemical	AF-2	SA	AF-2	AF-2	9AA
	Dose (µg/plate)	0.01	0.5	0.01	0.1	80
-	No colonies/plate	742 ± 20.0	702 ± 4.5	242 ± 18.9	648 ± 18.0	616 ± 41.5
	Chemical	2AA	2AA	2AA	2AA	2AA
	Dose (µg/plate)	1	2	10	0.5	2
+	No colonies/plate	1204 ± 51.4	413 ± 15.6	878 ± 88.1	518 ± 38.6	314 ± 34.8

Table 2: Mutagenicity of dicumyl peroxide in bacteria (II)

				No colonies/plate
+/- S9mix	DCP (µg/plate)	TA100	TA1535	WP2 uvrA	TA98	TA1537
-	0	127 ± 20.0	14 ± 0.6	22 ± 1.2	23 ± 3.5	7 ± 3.2
-	313	129 ± 12.3	14 ± 2.6	22 ± 4.6	19 ± 2.6	5 ± 2.0
-	625	139 ± 9.0	10 ± 2.5	25 ± 8.6	21 ± 2.6	6 ± 0.0
-	1250	124 ± 5.5	11 ± 3.0	17 ± 4.6	21 ± 2.6	5 ± 5.0
-	2500	109 ± 7.8	11 ± 2.0	23 ± 1.5	18 ± 2.6	6 ± 0.6
-	5000	123 ± 23.0	9 ± 4.5	18 ± 1.5	19 ± 1.2	4 ± 0.6
+	0	127 ± 20.1	11 ± 2.1	31 ± 1.2	18 ± 1.7	15 ± 5.2
+	313	161 ± 15.6	13 ± 1.2	28 ± 3.8	26 ± 5.5	8 ± 2.0
+	625	137 ± 19.6	12 ± 3.6	35 ± 3.5	26 ± 6.4	16 ± 4.9
+	1250	139 ± 13.2	9 ± 0.6	28 ± 3.1	22 ± 2.6	10 ± 4.6
+	2500	131 ± 8.7	8 ± 5.1	33 ± 1.0	27 ± 1.5	13 ± 4.6
+	5000	125 ± 9.5	9 ± 5.7	27 ± 5.7	21 ± 4.4	6 ± 2.1
	Chemical	AF-2	SA	AF-2	AF-2	9AA
	Dose (µg/plate)	0.01	0.5	0.01	0.1	80
-	No colonies/plate	649 ± 28.5	714 ± 56.2	216 ± 8.7	640 ± 20.0	611 ± 99.0
	Chemical	2AA	2AA	2AA	2AA	2AA
	Dose (µg/plate)	1	2	10	0.5	2
+	No colonies/plate	970 ± 54.2	347 ± 12.6	1020 ± 72.7	440 ± 63.5	237 ± 30.1

 

At all concentrations of dicumyl peroxide precipitate was observed on the surface of the agar plates.

Applicant's summary and conclusion

Conclusions:

Dicumyl peroxide did not induce gene mutation in bacteria when tested up to 5000 µg/plate, both with and without metabolic activation.

Executive summary:

A bacterial reverse mutation test (according to OECD 471) of bis(1-methyl-1-phenylethyl) peroxide in bacteria was carried out. This substance was not mutagenic in Salmonella typhimurium TA100, TA1535, TA98, TA1537 and Escherichia coli WP2 uvrA, with or without an exogenous metabolic activation system when tested up to the limit concentration of 5000 µg/plate.