Sodium methanesulphonate

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)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1983 version of guideline

Deviations:

yes

Remarks:

Contradictory information concerning precipitation

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Methanesulphonic acid

EC Number:

200-898-6

EC Name:

Methanesulphonic acid

Cas Number:

75-75-2

Molecular formula:

CH4O3S

IUPAC Name:

methanesulfonic acid

Test material form:

liquid

Method

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-treated rat liver S9-mix

Test concentrations with justification for top dose:

100, 500, 1000, 2500 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: distilled water

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

distilled water

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: 2-aminoanthracene

Remarks:

TA1535 and TA100: 5 µg/plate

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: 3/dose

DETERMINATION OF CYTOTOXICITY
- Method: other: decrease of revertant colonies

Evaluation criteria:

Criteria for cytotoxicity:
Reduced numbers of revertant colonies/plate compared with control plates, sparsity of background lawn when compared with control plates.

Criteria for genotoxocity:
Number of revertants at least twice that of spontaneous revertants, dose-related pattern, number of revertants/nmol > 0.01, reproducibility of the positive resonse.

Statistics:

No data on statistical test used.

Results and discussion

Test results

Key result

Species / strain:

S. typhimurium, other: TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: A precipitation of the S9-mix preparation was observed from the concentration of 2500 µg/plate in a concentration-related effect of increasing intensity in the first assay, while it only appeared at 5000 µg/plate in the second one.

BACTERIAL TOXICITY:
Methane sulfonic acid induced a marked toxicity on two tester strains: TA98 and TA100 at 1000 µg/plate with and without metabolic activation. In addition, it was observed that the S9-mix precipitated at those two concentrations.
Without metabolic activation at 5000 µg/plate, a moderate toxic effect was noted on TA100, whereas on TA98 a decrease of the revertant colony numbers with a sparse background was noted.
Therefore, the currently used concentrations were selected for the genotoxicity study.

First study (CEL473A)
With or without a metabolic activation system, Methanesulfonic acid did not inducc any increase of the number of His+ revertant colonies/plate, whatever the concentration. With metabolic activation, an inhibition of the bacterial background lawn was observed on the five tester strains at 5000 µg/plate, associated to a diminution of the revertant colonies number for TA1535 and TA1538 only. No such diminution was notcd on the other tester strains: therefore, the toxic effect noted on TA98 and TA100 was not as marked as that observed during the preliminary study. Furthermore, precipitation of the S-9 mix preparation was observed from the concentration of 2500 µg/plate, in a concentration-related effect of increasing intensity.

Second study (CEL473B)
There was no increase in the number of His+ revertant colonies/plate at either dose of Methanesulfonic acid on any of the five Salmonella typhimurium tester strains.
The results of this second study confirm the non-genotoxicity of Methanesulfonic acid at the highest concentration of 5000 µg/plate and at lower concentrations, both in the presence and absence of metabolic activation.
During the second study, without metabolic activation, an inhibition of the bacterial background lawn was observed on the five tester strains studied, with diminution of the revertant colonies number on TA1537, TA1538, TA98 and TA100 only.
These observations somewhat differ from those noted during the first study and seem to indicate that the concentration of 5000 -µg/plate, with metabolic activation, is at the limit of toxicity. Furthermore, S-9 mix precipitated at 5000 µg/plate.

Applicant's summary and conclusion

Conclusions:

Methanesulfonic acid was not genotoxic in the Ames test, with and without metabolic activation.

Executive summary:

The genotoxic potential of Methanesulfonic acid was assessed by the Ames test on five Salmonella typhimurium tester strains: TA1535, TA1537, TA1538, TA100 and TA98, both in the absence and presence of metabolic activation. Methanesulfonic acid was dissolved in distilled water and tested at concentrations ranging from 100 to l0000 µg/plate. The compound proved to be very toxic (inhibition of bacterial background lawn and diminution of the reverse colonies number) on TA100 and TA98, with and without metabolic activation at 10000 µg/plate only. Without metabolic activation at 5000 µg/plate, the toxic effect observed was less pronounced on TA 100, and TA98; and for TA98 only, the colonies revertant number diminished without inhibition of the background lawn. Consequently, the concentrations selected for the genotoxicity studies were 100, 500, 1000, 2500 and 5000 µg/plate. Whether in the presence or in the absence of metabolic activation, no increase was observed in the number of His+ revertant colonies/plate at any of the concentrations tested, on the five Salmonella typhimurium tester strains, in either study. An inhibition of bacterial background lawn was also noted for the five strains at 5000 µg/plate with metabolic activation. The diminution of the number of the reverse colonies at 5000 µg/plate for some strains was not reproducible in the two studies, which seemed to indicate that this concentration is at the lirnit of methanesulfonic acid toxicity, with metabolic activation. In addition, at 5000 µg/plate the compound provoked a precipitate of the S-9 mix preparation. In conclusion, Methanesulfonic acid was not genotoxic in the Ames test, with and without mctabolic activation.