Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Near-guideline GLP-compliant study, adequate for evaluation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1981
Report Date:
1981

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)
Principles of method if other than guideline:
Following an initial toxicity screen, the test substance was tested using L5176Y TK+/- cells in the absence and presence of Aroclor 1254-induced rat S9 fraction (2 day expression period).
GLP compliance:
yes
Remarks:
QAU compliance statement dated 25 September 1981
Type of assay:
mammalian cell gene mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Aqueous solution containing ca. 70wt% TBHP (CAS No. 75-91-2)
- Lot/batch No.: test article #81004

Method

Target gene:
Thymidine kinase locus; TK +/- to TK -/-
Species / strain
Species / strain / cell type:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat S9
Test concentrations with justification for top dose:
Preliminary toxicity test, with and without S9: 0.001, 0.01, 0.1, 1.0, 10 and 100 ul/ml

Main test, without S9:
Test 1 and Test 2: 0.0013, 0.0018, 0.0024, 0.0032, 0.0042, 0.0056, 0.0075, 0.010 and 0.013 ul/ml;
Test 3: 0.0013, 0.0018, 0.0024, 0.0032, 0.0042, 0.0056, 0.0075, 0.010, 0.013 and 0.018 ul/ml
Main test, with S9:
Test 1: 0.013, 0.018, 0.024, 0.032, 0.042, 0.056, 0.075, 0.10, 0.13 and 0.18 ul/ml
Test 2: 0.018, 0.024, 0.032, 0.042, 0.056, 0.075, 0.10, 0.13, 0.18 and 0.24 ul/ml
Test 3: 0.024, 0.032, 0.042, 0.056, 0.075, 0.10, 0.13, 0.18, 0.24 and 0.32 ul/ml

Comment: purity not reported, all doses nominal
Controls
Negative solvent / vehicle controls:
yes
Remarks:
acetone
Positive controls:
yes
Positive control substance:
other: -S9 = ethylmethanesulfonate (0.5 and 1.0 ul/ml); +S9 = 7,12-dimethylbenz(a)anthracene (5.0 or 7.5 ul/ml)
Evaluation criteria:
Mutation frequency for the treated plates was compared with that of the control plates. A two-fold increase in mutation frequency was considered to reflect a positive response.

Results and discussion

Test results
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
- consistent findings in all 3 tests
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Remarks:
- the test concentrations selected to be below threshold for cytotoxicity (0.1 ul/ml without S9, 1 ul/ml with S9)
Vehicle controls validity:
valid
Positive controls validity:
valid

Any other information on results incl. tables

Test 1 and test 2 were compromised due to a high level of contamination but still demonstrated a positive mutagenic response both in the absence and presence of S9 fraction. These findings were confirmed by test 3, where no contamination was present.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive without metabolic activation
positive with metabolic activation

The test substance was positive in L5178Y TK+/- cells in the absence and in the presence of Aroclor 1254-induced rat S9 fraction.
Executive summary:

The mutagenic potential of TBHP was evaluated in L5178Y TK+/- cells in the absence or presence of Aroclor 1254-induced rat S9 fraction. The investigation was GLP-compliant and followed EU Method B.17, and was repeated three times due to contamination of the initial trials. A positive mutagenic response was recorded on all occasions, both in the absence and presence of S9 fraction. The results demonstrate  that TBHP is a mammalian cell mutagen in L5178Y TK+/- cells in vitro.