Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015-10-02 to 2015-10-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: bulk
Specific details on test material used for the study:
Batch 1507511210

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Metabolic activation system:
S9 liver microsomal fraction (phenobarbital and ß-naphthoflavone induced)
Test concentrations with justification for top dose:
31.6, 100, 316, 1000, 2500, and 5000 µg/plate
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
sodium azide
methylmethanesulfonate
other: 4-nitro-o-phenylene-diamine, 2- aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: experiment I in agar (plate incorporation); experiment II preincubation

DURATION
- Preincubation period: 60 min at 37 °C
- Exposure duration: at least 48 h at 37 °C

NUMBER OF REPLICATIONS: 3 plates per concentration and strain

DETERMINATION OF CYTOTOXICITY
- Method: background lawn, reduction in the number of revertants down to a mutation factor of approx. < 0.5 in relation to the solvent control.

OTHER: Colonies were counted using a ProtoCOL counter (Meintrup DWS Laborgeräte GmbH).
Tester strains TA 1535 and TA 1537 were counted manually.
Evaluation criteria:
Validity:
A test is considered acceptable if for each strain:
- the bacteria demonstrate their typical responses to ampicillin
- the negative control plates with and without S9 mix are within laboratory historical ranges
- corresponding background growth on negative control, solvent control and test plates is observed
- the positive controls show a distinct enhancement of revertant rates over the control plate
- at least five different concentrations of each tester strain are analysable.

Evaluation of Mutagenicity:
A test item is considered as mutagenic if:
- a clear dose-related increase in the number of revertants occurs and/or
- a biologically relevant positive response for at least one of the dose groups occurs
in at least one tester strain with or without metabolic activation.

A biologically relevant increase is described as follows:
- if in tester strains TA98, TA100 and TA 102 the number of reversions is at least twice as high
- if in tester strains TA 1535 and TA 1537 the number of reversions is at least three times higher
than the reversion rate of the solvent control.

Results and discussion

Test results
Key result
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Guanidine Thiocyanate is considered to be non-mutagenic in this bacterial reverse mutation assay.
Executive summary:

In a reverse gene mutation assay in bacteria according to OECD guideline 471, strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 of S. typhimurium were exposed to Guanidinium Thiocyanate, at concentrations of 31.6, 100, 316, 1000, 2500, and 5000 µg/plate in two independent experiments. The first experiment was conducted as plate incorporation assay, the second as pre-incubation test, both in the absence and presence of a mammalian metabolic activation.

No precipitation of the test item was observed in any of the experiments. In experiment I no toxic effects were noted up to the highest concentration. In experiment II in some strains toxic effects were observed at 2500 and 5000 µg/plate.

No biological relevant increases in revertant colony numbers of any of the five tester strains were observed following treatment with Guanidine Thiocyanate at any concentration level, neither in the presence nor absence of metabolic activation in experiment I and II.

The reference mutagen induced a distinct increase of revertant colonies indicating the validity of the experiments.