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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
March 5-18, 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
The test substance was stored at ,-20 degrees Celsius, instead of between -16 and -20 degrees celsius. However, it was stated in the test substance information sheet that the storage conditions should be <-18 degrees Celsius, therefore the deviation is c
Principles of method if other than guideline:
No further information required.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): dibutyloxostannane
- Molecular formula (if other than submission substance): C8 H18 OSn
- Molecular weight (if other than submission substance): 248.92
- Structural formula attached as image file (if other than submission substance): see Fig.
- Substance type: white powder
- Analytical purity: 98.09% Dibutyltin oxide
- Composition of test material, percentage of components: 98.09% Dibutyltin oxide, 0.49% di-(i,n)-butyltin oxide, 0.40% monobutyltin oxide, 0.86% tetrabutyldiethyl distannane, 0.17% tributyltin oxide
- Lot/batch No.: 1704
- Expiration date of the lot/batch: October 2003
- Stability under test conditions:
- Storage condition of test material: at <-20 degrees C, in the absence of light
- Other: received 12 October 2003
- Expiry date: October 2003
- Supplier: sent to TNO at the request of ORTEP Asociation Stabilizer Task Force
- TNO Test Substance No.: IMW-01040160B

Method

Target gene:
rfa, uvrB/A,and R-factor
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
S9 liver homogenate (S9-mix)
Test concentrations with justification for top dose:
Assay 1: 7, 21, 62, 185, 556, 1667, 5000 µg/plate.
Assay 2: 1.25, 2.5, 5, 10, 20 µg/plate
Vehicle / solvent:
Methanol
Controlsopen allclose all
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
For strain TA1535 and strain TA100 in the absence of the S9-mix
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
For strain TA1537 in the absence of the S9-mix
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
For strain TA1535, TA98, TA100, and WP 2 uvrA in the presence of the S9-mix
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
For strain TA98 in the absence of the S9-mix
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
other: N-ethyl-N-nitrosourea
Remarks:
For strain WP 2 uvrA in the absence of the S9-mix
Untreated negative controls:
yes
Remarks:
solvent
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
For strain TA1537 in the presence of the S9-mix
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 37 degrees Celsius for 48-72 hours
Evaluation criteria:
The mutagenicity study is considered valid if the mean colony counts of the control values of the strains are within acceptable ranges, if the results of the positive controls meet the criteria for a positive response, and if no more than 5% of the plates are lost through contamination of other unforeseen events.

A test substance is considered to be positive in the bacterial gene mutation test if the mean number of revertant colonies on the test plates is concentration-related increased or if a reproducible two-fold or more increase is observed compared to that on the negative control plates.

A test substance is considered to be negative in the bacterial gene mutation test if it produces neither a dose-related increase in the mean number of revertant colonies nor a reproducivle positive response at any of the test points.

Positive results from the bacterial reverse mutation test indicate that a substance induces point mutations by base substitutions or frameshifts in the genome of either Salmonella typhimurium and/or E. coli. Negative results indicate that under the test conditions, the test substance is not mutagenic in the tested strains.

In case of an inconclusive first assay, a second independant assay was conducted. The first mutagenicity assay is regarded inconclusive if a positive or equivocal response at only one concentrations is observed or if a positive or equivocal responses at several concentrations without a concentration-related increase are observed.
Statistics:
No statistical analysis was performed. Both numerical significance and biological relevance are considered together in the evaluation.

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:
not specified
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Genotoxic effects: negative both with and without metabolic action.
In both the absence and presence of S9-mix and in all strains, dibutyloxostannane did not cause a more than two-fold or a dose-related increase in the mean number of revertant colonies appearing in the test plates compared to the background spontaneous reversion rate observed with the negative control.

The mean number of his+ and trp+ revertant colonies of the negative controls were within the acceptable range, and the positive controls gave the expected increase in the mean number of revertant colonies.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'. Remarks: all strains

Any other information on results incl. tables

Table 1. Bacterial reverse mutation test with dibutyloxostannane (first assay)
Average number of revertants per plate
Dose ug/plate TA 1535 TA1537 TA98 TA 100 E-coli
without S9 with S9 without S9 with S9 without S9 with S9 without S9 with S9 without S9 with S9
0 25 24 17 12 35 51 168 171 37 40
7 17 17 20 12 34 49 155 169 34 39
21 11 15 5 5 23 29 109 105 26 25
62 0 0 0 0 0 0 0 0 24 13
185 0 0 0 0 0 0 0 0 11 5
556 0 0 0 0 0 0 0 0 0 0
1667 0 0 0 0 0 0 0 0 0 0
5000 0 0 0 0 0 0 0 0 0 0
Positive control 713 525 1220 348 2078 810 886 2013 228 1720
Table 2. Bacterial reverse mutation test with dibutyloxostannane (second assay)
Average number of revertants per plate
Dose ug/plate TA 1535 TA1537 TA98 TA 100 E-coli
without S9 with S9 without S9 with S9 without S9 with S9 without S9 with S9 without S9 with S9
0 26 24 12 15 25 35 153 161 21 27
1.25 19 23 13 14 25 38 174 169 25 26
2.5 11 17 5 9 20 31 142 180 25 26
5 16 21 9 8 23 35 153 174 25 21
10 13 17 6 6 20 35 132 138 21 32
20 10 12 3 4 16 18 95 95 23 22
Positive control 489 428 811 295 1170 965 509 1635 195 1045

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative In both the absence and presence of S9-mix, and in all strains

It is concluded that the results obtained with the test substance in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, and TA 100, and in the E. coli strain WP2 uvrA, in both the absence and presence of the S9-mix, indicate that dibutyloxostannane was not mutagenic under the conditions employed in this study.
Executive summary:

Dibutyloxostannane was examined for mutagenic activity in the bacterial reverse mutation test using the histidine-requiring Salmonella typhimurium strains TA 1535, 1537, 98 and 100 and the tryptophan-requiring E. coli strain WP2 uvrA, and a liver fraction of Aroclor 254 -induced rats from metabolic activation (S9 -mix). In both the absence and the presence of S9 -mix and in all strains, dibutyloxostanane did not cause a more than two-fold or a dose-related increase in the mean number of revertant colonies appearing in the test plates compared to the background spontaneous reversion rate observed with the negative control. The mean number of his+ and trp+ revertant colonies of the negative controls were within the acceptable range, and the positive controls gave the expected increase in the mean number of revertant colonies. It is concluded that dibutyloxostannane was not mutagenic under the conditions employed in this study.