Hexanoic acid, 3,5,5-trimethyl-, tin(2+) salt (2:1)

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Read-across from a well documented publication

Data source

Reference

Reference Type:

publication

Title:

Chemical Mutagenesis at the Thymidine Kinase Locus in L5178Y Mouse Lymphoma Cells: Results for 31 Coded Compounds in the National Toxicology Program

Author:

Myhr B C and Caspary W J

Year:

1991

Bibliographic source:

Environmental and Molecular Mutagenesis 18; 51-83 (1991)

Materials and methods

Principles of method if other than guideline:

Method: Clive et al. (1979), Mitchell et al. (1988), and Myhr and Caspary (1988)

GLP compliance:

not specified

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Tin dichloride

EC Number:

231-868-0

EC Name:

Tin dichloride

Cas Number:

7772-99-8

Details on test material:

Tin Dichloride [CAS No. 7772-99-8]; purity not reported, source: National Toxicology Program Chemical Repository.

Method

Target gene:

thymidine kinase (TK) locus

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: RPM1 1640 or Fischer's  medium
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes ervery 2-3 month
- Periodically checked for karyotype stability: yes/no
- Periodically "cleansed" against high spontaneous background: yes/no

Metabolic activation:

with and without

Metabolic activation system:

S9 homogenate was prepared from the livers of   Aroclor 1254-induced male Fischer 344 rats.

Test concentrations with justification for top dose:

0-80 ug/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: not soluble in water

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without S9

Migrated to IUCLID6: 5 nL/mL

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: MCA (3-methylcholanthrene, 2.5 ug/mL

Remarks:

with S9

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium(Fisher's treatment medium)

DURATION
- Exposure duration: incubation 4 hours
- Expression time (cells in growth medium): 48 h
- Selection time (if incubation with a selection agent): 48 h


SELECTION AGENT (mutation assays): trifluorothymidine (TFT)

NUMBER OF REPLICATIONS: two

NUMBER OF CELLS EVALUATED: 300000/plate seeded

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth, cloning efficiency

Evaluation criteria:

Each experiment was evaluated for compliance with the quality control criteria before it was accepted for evaluation of the response. The upper limit for an acceptable CE was increased from 115% to 120%. The overall evaluation of the test chemical in the mouse lymphoma assay was based on the test condition yielding the greatest response.

Statistics:

Statistical analyses were performed using a computer program  for both the MF trend and for comparisons between each dose level and the  solvent control.

Results and discussion

Test results

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

Stannous chloride was not mutagenic to L5178Y mouse lymphoma cells. 
The lowest average RTG values obtained for treatments with soluble concentrations ranged from 30 -35 % without S9 to ca. 60 % with S9.
Precipitation was observed at 80 µg/mL in culture medium, and a slightly acidic pH shift in the medium was noted at 50 µg/mL.

Remarks on result:

other: strain/cell type: mouse lymphoma L5178Y cells

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

Tin dichloride is considered to be non-mutagenic, in the L5178Y mouse lymphoma cell mutation assay.

Executive summary:

In a mammalian gene mutation assay, mouse lymphoma cells (L5178 Y; thymidine kinase locus) cultured in vitro were exposed to tin dichloride up to a precipitating concentration of 80 µg/mL. The induction of small and large mutant colony populations was analyzed in the present and absence of mammalian metabolic activation.

 

Some erratic increases in MF of 1.5 to 1.8 fold were observed and these changes bore no relation to toxicity and were not repeatable among the three nonactivation assays and two S9 activation assays. The lowest average RTG values obtained for treatments with soluble concentrations ranged from 30 -35% without S9 to ca. 60% with S9. Precipitation was observed at 80 µg/mL in culture medium, and a slightly acidic pH shift in the medium was noted at 50 µg/mL.

The test chemical was dosed into medium from a solution in DMSO because it was not soluble in water, even at 100 µg/mL, which shifted the pH to 3.5. This observation suggested that the actual material tested was tin dichloride, which forms an insoluble basic salt in excess water. Since tin dichloride itself is soluble in water, possibly different toxic (and mutagenic) properties would have been obtained had the test chemical been more soluble and accessible to the cells. Also, the reduced toxicity in the presence of S9 mix suggested that tin dichloride is capable of interacting (in as yest unknown ways) with metabolic activation systems.

 

In conclusion, in the L5178Y mouse lymphoma cell mutation assay, tin dichloride is considered to be non-mutagenic.