Di-tert-pentyl peroxide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study, K1a

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1983

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Di-tert-pentyl peroxide

EC Number:

234-042-8

EC Name:

Di-tert-pentyl peroxide

Cas Number:

10508-09-5

Molecular formula:

C10H22O2

IUPAC Name:

2-methyl-2-[(2-methylbutan-2-yl)peroxy]butane

Test material form:

other: liquid

Details on test material:

- clear slight yellow tinted liquid, purity 54.8 %, received at Life Science Research on 10 January 1992
- It was kept at approximately 4°C in the dark, in the original container and stored in a flame proof cabinet.

Method

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

activating system derived from rat liver (S-9 mix)

Test concentrations with justification for top dose:

25-2500 µg/plate

Vehicle / solvent:

Ethanol

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Sodium azide: without S9 for TA 1535 and TA 100 / 2-aminoanthracène for TA1535 with and without S9 / 9-Aminoacridine forTA1537 with S9 / 2-Nitrofluorenefor TA 98 without S9 / Benzo-a-pyrene for TA1537, 98 and 100, with and without S9

Results and discussion

Test results

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:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Any other information on results incl. tables

Young male CD rats, ca. 200 g bodyweight, were obtained from Charles River Breeding Laboratories (U.K.), Margate, Kent. Aroclor 1254(500 mg/kg bodyweight in corn oil) was administered as a single intraperitoneal injection to induce microsomal enzyme activity.

 

Four days after treatment, the animals were fasted overnight and then killed by cervical dislocation. The livers were removed, washed in cold 0.15M KCl, then homogenised with more of the same medium (approximately 3 ml per g wet liver)in an homogeniser. Homogenates were centrifuged at 9000 g for 10 minutes and supernatants collected and stored at -80°c until required for preparation of the S-9 mix. Supernatant is used within 3 months of preparation.

Applicant's summary and conclusion

Conclusions:

Di-tert-amyl peroxide was devoid of mutagenic activity under the conditions of the test.

Executive summary:

Di-tert-amyl peroxide (purity 84.8 %) was examined for mutagenic activity in four histidine-dependent auxotrophs of Salmonella typhimurium, strains TA 98, TA 100, TA 1535 and TA 1537, using pour-plate assays. The procedures used complied with OECD Guideline for Testing of Chemicals No. 471 (issued 1983).

The studies, which were conducted in the absence and presence of an activating system derived from rat liver (S-9 mix), employed a range of levels of test item from 25 to 2500 µg per plate, selected following a preliminary toxicity test in strain TA 98, and included solvent (ethanol) controls with and without S-9 mix.

No increases in reversion to prototrophy were obtained with any of the four bacterial strains, either in the presence or absence of S-9 mix.

Only on one occasion of testing in strain TA 100 was any evidence of toxicity towards the bacterial strains obtained (observed as a slight reduction in revertant colony numbers), although the test item had clearly shown marked toxicity (reduction in revertant colony numbers and thinning of the background lawn) at 2500 µg per plate in the preliminary toxicity tests.

Marked increases in the number of revertant colonies were induced by the known mutagens benzo[a]pyrene, 2-nitrofluorene, 2-aminoanthracene, 9-aminoacridine and sodium azide when examined under similar conditions.

 

It was concluded that di-tert-amyl peroxide was devoid of mutagenic activity under the conditions of the test.