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Genetic toxicity: in vitro

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in vitro gene mutation study in bacteria
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: 2d: Test procedure in accordance with national standard methods with acceptable restrictions (few datails in documentation)

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Dibenzoyl peroxide
EC Number:
EC Name:
Dibenzoyl peroxide
Cas Number:
Molecular formula:
benzoyl benzenecarboperoxoate
Details on test material:
The test sample, a white granulated material, designated Lucidol and stated to consist of 75% di-benzoyl peroxide and 25% water, was received from the principal in November 1978. Appropriate solutions in acetone were prepared immediately before use.


Species / strain
Species / strain / cell type:
other: S. typhimurium TA 1535, TA 1537, TA 98 , TA 100 and TA 1538
Details on mammalian cell type (if applicable):
The Salmonella typhimurium mutants were provided by Dr. B.N. Ames, Berkeley, California, USA and stored as frozen cultures at -80°C. To obtain fresh cultures for mutagenesis testing, nutrient broth is inoculated with the frozen culture and grown up overnight with shaking at 37°C.
The reversion properties of the strain were checked, using the mutagens 2-a+ninoanthracene and 9-aminoacridine.
In addition, the strains were checked Eor histidine requirements for sensitivity to crystal violet and well as for resistance to ampicilline.
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
liver homogenate of Aroclor-induced rats (1254/kg ip, 7 days before sacrifice). The metabolic activation properties of the Iiver homogenate were checked with S. typh. TA 98 and 4-ABP.
Test concentrations with justification for top dose:
0.8 up to 20-100, and 100-500 µg per plate
Untreated negative controls:
Negative solvent / vehicle controls:
True negative controls:
Positive controls:
Positive control substance:
other: 2-aminoanthracene and 9 aminoacridine
not applicable

Results and discussion

Test results
Species / strain:
other: S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Cytotoxicity / choice of top concentrations:
other: only at highest levels (100-500 µg per plate)
Vehicle controls validity:
Untreated negative controls validity:
not applicable
Positive controls validity:
Remarks on result:
other: all strains/cell types tested
Migrated from field 'Test system'.

Applicant's summary and conclusion

The present results did not reveal any mutagenic activity of the test material in the Salmonella/microsome mutagenicity test.
Executive summary:

The potential of benzoyl peroxide to induce reverse mutation in Salmonella typhimurium (strains: TA 1535, TA 1537, TA 98, TA 100 and TA 1538) was evaluated in accordance with the Ames procedure, in presence and absence of metabolic activation. No data is available about compliance with the Principles of Good Laboratory Practice.

Incorporation of 0.8 up to 20 - 100 µg of the test material per plate did not induce an increase in the number of his+revertants with any of the five tester strains either in the presence or in the absence of S-9 mix. At higher levels, i.e. 100 - 50011g/plate,the testmaterial was toxic to the bacteria as seen by a less densebackground lawn of bacterial growth and a decrease in the number of his*revertants.From the present resuits it can be concluded thatbenzoyl peroxideat levels up to 20 - 100 ub/plate did notreveal any mutagenic activity in the plate incorporationassay.with S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 or TA 100 in the presence or absence of the liver microsome activation system under the test conditions employed in this evaluation. At higher levels chemical toxicity interfered with the mutagenicity testing.