12-wolframosilicic acid

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

12-wolframosilicic acid

EC Number:

234-719-8

EC Name:

12-wolframosilicic acid

Cas Number:

12027-38-2

Molecular formula:

H.1/4O40SiW12

IUPAC Name:

tetrakis(hexaoxocyclotritungstoxane); silicic acid

Test material form:

solid

Specific details on test material used for the study:

Identification: Tungstosilicic-acid
Batch: MKBR8664V
Purity: >99.9%
Physical state/Appearance: White crystalline solid
Expiry Date: 11 February 2016
Storage Conditions: Room temperature over silica gel in the dark

Method

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S9 Microsomal fraction

Test concentrations with justification for top dose:

Plate incorporation method: 1.5, 5, 15, 50, 150, 500, 1500 and 5000 μg/plate. The top dose is the maximum recommended by the guideline. Pre-incubation method: 15, 50, 150, 500, 1500 and 5000 μg/plate. The top dose is the maximum recommended by the guideline.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: water and 12.5mg/mL polyethylene glycol (PEG).
- Justification for choice of solvent/vehicle: Water is an inert solvent. PEG was used in order to overcome problems with the test substance preventing setting of the Agar to a gel. The PEG helped overcome the setting problem.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

9-aminoacridine

N-ethyl-N-nitro-N-nitrosoguanidine

benzo(a)pyrene

other: 2-aminoanthracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation) and pre-incubation methods

DURATION - plate incorporation method
- incubation conditions: 37 °C± 3 °C
- Exposure duration: 48 hours
DURATION - pre-incubation method
- Preincubation period: 7 °C± 3 °C for 20 minutes (with shaking) prior to addition of 2 mL of molten amino-acid supplemented media and subsequent plating onto Vogel-Bonner plates.

NUMBER OF REPLICATIONS: 3

- OTHER: Evaluation method: automated colony counting system.

Evaluation criteria:

1. A dose-related increase in mutant frequency over the dose range tested (De Serres and Shelby, 1979).
2. A reproducible increase at one or more concentrations.
3. Biological relevance against in-house historical control ranges.
4. Statistical analysis of data as determined by UKEMS (Mahon et al., 1989).
5. Fold increase greater than two times the concurrent solvent control for any tester strain (especially if accompanied by an out-of-historical range response (Cariello and Piegorsch, 1996)).
A test item will be considered non-mutagenic (negative) in the test system if the above criteria are not met.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Not mutagenic

Executive summary:

In a guideline GLP Ames reverse bacterial mutation study, the substance tungstosilicic acid was found to be not mutagenic in the 5 strains tested both with and without metabolic activation (S typhimurium TA98, TA100, TA1535, TA1537 and E coli WP2uvrA.)