Methyl toluene-4-sulphonate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2005

Report date:

2004

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 487 (In vitro Mammalian Cell Micronucleus Test)

Version / remarks:

Micronucleus test in mouse lymphoma
(L5178Y) cells

Deviations:

not specified

Principles of method if other than guideline:

Mouse lymphoma cells were obtained from Hofmann-La Roche (Basel, Switzerland). Based on the data of a preliminary solubility test and within the limit to test up to 10 mM or 5 mg/ml (whichever was lower), 10 concentrations were selected for the main experiment.
All compounds were dissolved in DMSO. The cells were diluted in RPMI-10 medium (Gibco) to 200,000 cells/ml for the 3 h treatment and to 100,000 cells/ml for the 20 h treatment (cell count determined by use of a SYSMEX cell counter), respectively. The desired final concentration was obtained by adding 10 microlitres of DMSO-dissolved test compound to 1 ml cell suspension (sufficient for four wells of 200 microlitre each), resulting in 1% DMSO in the treatment medium. Incubation was conducted with 96-well plates with four replicates per test compound concentration.

For the micronucleus experiment, the cells were treated with the test compound solution for 3 h (with or without S9) or for 20 h (without S9 only). After the treatment, cells were washed with phosphate-buffered saline and further incubated with fresh medium for 21 h in case of 3 h treatment, or 28 h in case of 20 h treatment. Before sampling, a cell count for one of the replicates of each concentration was determined as cytotoxicity parameter, and the concurrent negative control was set to 100%. Based on the relative cell count, the concentration that inhibited growth by approximately 50–70%, and two lower concentrations showing less cytotoxicity were chosen for analysis. The selected cell suspensions were then spread on glass slides by cytocentrifugation (Shandon Cytospin). Cells were fixed and stained with Schiff’s reagent (nucleus staining) and Congo-Red counterstaining for the cytoplasm. Two thousand cells (1000 cells per culture) were analyzed from at least three concentrations of each test compound, as well as from negative and positive controls.

GLP compliance:

not specified

Type of assay:

in vitro mammalian cell micronucleus test

Test material

Test material information

Constituent 1

Reference substance name:

Methyl toluene-4-sulphonate

EC Number:

201-283-5

EC Name:

Methyl toluene-4-sulphonate

Cas Number:

80-48-8

Molecular formula:

C8H10O3S

IUPAC Name:

methyl 4-methylbenzene-1-sulfonate

Specific details on test material used for the study:

Source: Fluka, Switzerland, no. 89800

Method

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

no

Details on test system and experimental conditions:

The historical average solvent control data for micronucleus induction were as follows: 3 h treatment without S9, 0.73 ± 0.13; 20 h treatment without S9, 0.82 ± 0.18; 3 h treatment with S9, 0.78 ± 0.16.

Evaluation criteria:

A result was considered positive when
the micronucleus frequency was at least twice the historical negative control value as well as twice the actual concurrent negative solvent control value.
These criteria are based on an in-house validation study of the assay.

Results and discussion

Test results

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

mutagenic potential (based on QSAR/QSPR prediction)