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Toxicological information

Genetic toxicity: in vitro

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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:
1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: according th GLP and according to OECD and EC guidelines.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report Date:
1999

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
according to
Guideline:
other: UKEMS Guidelines (1990), Japanese MHW (1989) and MAFF (1985) Guidelines and ICH Harmonised Tripartite Guideline (1997)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Dapsone, batch no. 70522014, solid white powder, received on December 18 1998. Stored at 1-10 degrees C in the dark.
Source : Sigma Aldrich Co Ltd, Gillingham UK

Method

Target gene:
Tryptophan and Histidine-requring genes in Salmonella and Escherichia
Species / strainopen allclose all
Species / strain / cell type:
E. coli, other: WP2 pKM101
Species / strain / cell type:
E. coli WP2 uvr A pKM 101
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
Araclor 1254-induced rat liver post-mitochondrial fraction (S-9)
Test concentrations with justification for top dose:
8, 40, 200, 1000, 5000 micrograms/plate in the range-finder experiment
8, 40, 200, 1000, 5000 and 4, 20, 100, 500, 2500 micrograms /plate were used in the main experiments
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Remarks:
treatment with solvent
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
Positive controls:
yes
Remarks:
treatment with appropriate stock positive control solution
Positive control substance:
sodium azide
Remarks:
other positive controls used were 9-aminoacridine (AAC), 2-aminoanthracene (AAN), 4-nitrochinoline (NQO), and 2-nitrofluorene(2NF)
Details on test system and experimental conditions:
the plating assay was chosen for all experiments.
Incubation was for three days in the dark at 37 degrees Celcius.
Statistics:
M-statistics to check whether ther data were Poisson-distributed,
Dunnetts test to compare the counts of each data point with the control.
Linear regression analysis

Results and discussion

Test resultsopen allclose all
Species / strain:
E. coli WP2 uvr A pKM 101
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
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:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
No positive result has been observed in any of the strains .
In addition to E.coli strain E. coli WP2 uvr A pKM 101 also E.coli strain WP2 pKM 101 was tested.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Dapsone did not induce reverse gene mutation in bacteria (4 Salmonella strains and 2 E.coli strains). The concentrations applied showed at the high end some toxicity in the absence and presence of S-9 activating enzymes.
Executive summary:

A bacterial Ames test acording to OECD guideline 471 and the EC guidelines was performed with the Salmonella strains TA 98, TA 100, TA 1535, and TA 1537, as well as with the Escherichia coli strains WP2 pKM 101, and WP2 uvrA pKM 101.

All strains were tested in the presence and absence of S-9 rat liver activating enzymes. None of the strains showed a significant increase of revertant colonies (mutants) neither in the presence nor in the absence of the metabolic rat-enzymes.

It is therefore concluded that Dapsone is not mutagenic under the bacterial Ames assay.