Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
March-April 1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: OECD 471 protocol study under GLP; however 4 required strains were used, but no additional strain having AT base pairs at the primary reversion site (such as TA 102 or E. coli WP2 strains; as required in current OECD 471 (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report Date:
1990

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
see below
Qualifier:
according to
Guideline:
EPA OPPTS 870.5265 (The Salmonella typhimurium Bacterial Reverse Mutation Test)
Principles of method if other than guideline:
4 required strains were used, but no additional strain having AT base pairs at the primary reversion site (such as TA 102 or E. coli WP2 strains; as required in current OECD 471 (1997)).
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Armogard S462
- Date of receipt: 21 March 1990
- Substance type: fine white powder
- Physical state: solid
- Analytical purity: 97.8%
- Lot/batch No.: AGH 01/96
- Stability under test conditions:stable
- Storage condition of test material: at ambient temperature, in a desiccator

Method

Target gene:
reverse mutation to histidine independency
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
S9 mix (rat liver Aroclor 1254 induced)
Test concentrations with justification for top dose:
0, 5, 16, 50, 158 and 500 µg/plate
Vehicle / solvent:
Vehicle: distilled water
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
distilled water
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
5 µg/plate (- and + S9 mix)

Migrated to IUCLID6: TA1537, TA98, TA100
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
distilled water
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
1 µg/plate (- S9 mix)

Migrated to IUCLID6: TA98
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
distilled water
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
80 µg/plate (- S9 mix)

Migrated to IUCLID6: TA 1537
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
distilled water
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene / TA1535
Remarks:
2 µg/plate (- and + S9 mix)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
distilled water
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
2 µg/plate (- S9 mix)

Migrated to IUCLID6: TA1535 and TA100
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: overnight
- Exposure duration: 2 days

NUMBER OF REPLICATIONS: all plates prepared in triplicate

DETERMINATION OF CYTOTOXICITY
- Method: 2.5-5000 µg/plate using TA98. Toxicity was examined for the presence of a background lawn of non-revertant colonies;
toxicity is present by the absence ofr thinning of the background lawn. The lowest level causing visible thinning of the background
lawn of non-revertant cells was 500 µg/plate; this was therefore the top dose tested.
Evaluation criteria:
Increases in revertant colony numbers over control counts.
Statistics:
Not used.

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:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: none
- Effects of osmolality: none
- Evaporation from medium: none
- Water solubility: good
- Precipitation: no

RANGE-FINDING/SCREENING STUDIES: In the preliminary toxicity test, dose levels of 2.5 to 5000 µg/plate were tested. The lowest
level tested causing visible thinning of the background lawn was 500 µg/plate; this level was therefore selected as the top
exposure level.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Inhibition of growth and reduction in revertant colony numbers occurred in all strains at 500 µg/plate; reduction in revertant colony
numbers was also seen at the next lower level tested of 158 µg/plate in all strains on at least one occasion of testing in both the
absence and presence of S9 mix. It was concluded that the test material was non-mutagenic up to the maximum level tested of 500 µg/plate under the condition of this test. Although the tested strains (TA1537, TA1535, TA98 and TA100) may not detect certain
oxidising mutagens or cross-linikg agents, it is not expected that the test substance will do so. Therefore, it is concluded thatthere is no evidence of mutagenic potential of the test substance in this bacterial test system.
Executive summary:

Armogard S462 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 the OECD Guidelines for testing of chemicals (1983) and the EPA Toxic Substances Control Act Test Guidelines (1988). Each test, in each strain, was conducted on two separate occasions.

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 Armogard S462 from 5 to 500 µg per plate, selected following a preliminary toxicity test in strain TA 98. Al l tests included solvent (distilled water) controls with and without S-9 mix.

No increases in reversion to prototrophy were obtained with any of the four bacterial strains at the Armogard S462 levels tested, either in the presence or absence of S-9 mix. Inhibition of growth, observed as thinning of the background lawn of non-revertant cells and reduction in revertant colony numbers, occurred in all strains following exposure to Armogard S462 at 500 ug per plate. Reduction in revertant colony numbers was also seen with Armogard S462 at 158 µg per plate in all strains on at least one occasion of testing in both the absence and presence of S-9 mix.

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 Armogard S462 was devoid of mutagenic activity under the conditions of the test.