Lithium dihydrogen 5-sulphonatoisophthalate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 October 1995 thru 11 December 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

Reported as in accordance with methods and procedures described by Ames et. al. (1975) and Green and Muriel (1976).

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Lithium dihydrogen 5-sulphonatoisophthalate

EC Number:

256-275-4

EC Name:

Lithium dihydrogen 5-sulphonatoisophthalate

Cas Number:

46728-75-0

Molecular formula:

C8H6O7S.Li

IUPAC Name:

lithium dihydrogen 5-sulphonatoisophthalate

Test material form:

solid: particulate/powder

Details on test material:

- Moisture content: 6.5%
- Colour: Off-white

Specific details on test material used for the study:

Reported as: EC 95-0215, 5LiSIPA
Lot No.: 55503
CASRN: 46728-75-0
Chemical Name: 5-sulfo-1,3-benzenedicarboxylic acid, monolithium salt
Appearance: white to off-white solid
Purity: 93%
Water: 6.8%

Method

Target gene:

Mutations in the histidine operon of Salmonella typhimurium including hisG46, hisC3076 and hisD3052, and mutations in the tryptophan operon of Escherichia coli.

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 pKM 101

Metabolic activation:

with and without

Metabolic activation system:

Type and composition of metabolic activation system:
- source of S9 : Aroclor-induced S9 rat liver homogenate; Molecular Toxicology, Inc., Annapolis, MD
- method of preparation of S9 mix: Prepared immediately prior to use.
- concentration or volume of S9 mix and S9 in the final culture medium: 2 ml of S9 mix containing 0.2 ml S9 homogenate.

Test concentrations with justification for top dose:

In a range-finidng study, ten doses of 6.67 to 5,000 micrograms/plate were tested with TA100 and WP2uvrA. Definitive studies (in duplicate) were conducted at dose levels of 100, 333, 1000, 3330 and 5000 micrograms/plate both with or without S9 mix.

Vehicle / solvent:

Deionized water.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene, 2-nitrofluorene; sodium azide; ICR-191; and 4-nitroquinoline-N-oxide

Details on test system and experimental conditions:

Source of Tester Strains: Salmonella typhimurium strains were received from Dr. Bruce Ames, Department of Biochemistry, University of California. The E. coli strain WP2uvrA was received from the National Collection of Industrial Bacteria, Torrey Research Station, Scotland.

Inoculum: Overnight cultures for use in all testing procedures were inoculated by transferring a colony from the appropriate master plate to a flask containing culture medium. Overnight cultures (shaking at 125 +/- 25 rpm; incubation at 37 +/- 2 deg. C) in log phase or late log phase of growth were harvested.

Plate Incorporation Method: The test article, tester strain and S9 mix (where appropriate) were combined in molten agar and overlaid onto a minimal agar plate. After incubation of plates at 37 +/- 2 deg C for 48 +/- 8 hr, revertant colonies were counted. All doses, vehicle and positive controls were plated in triplicate.

Plate Counts: The numbers of revertant colonies per plate for vehicle controls and all plates containing test article were counted manually. Plate counts for positive controls were counted by automated colony counter.

Evaluation criteria:

A minimum of 3 non-toxic doses were required to evaluate assay data.

For tester strains TA98, TA100 and WP2uvrA, at least a 2-fold increase in the mean revertants per plate over the vehicle control was required for a positive response. This increase in mean number of revertants per plate had to be accompanied by a dose response to increase concentrations of the test article.

For tester strains TA1535 and TA1537, at least a 3-fold increase in the mean revertants per plate over the vehicle control was required for a positive response. This increase in mean number of revertants per plate had to be accompanied by a dose response to increase concentrations of the test article.

Statistics:

For all replicate platings, the mean revertants per plate and the standard deviation were calculated.

Results and discussion

Test results

Key result

Species / strain:

other: Salmonella TA1535, TA100, TA1537 and TA98; and E. coli WP2uvrA(pKM101)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

none observed at highest dose in the range-finding study or the main study

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

True negative controls validity:

not applicable

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

The test substance did not cause a positive increase in the number of revertants per plate of any of the tester strains either in the presence or absence of microsomal enzymes prepared from Arochlor-induced rat liver (S9) mix.

Executive summary:

In a GLP guideline study consistent with OECD 471 - Bacterial Reverse Mutation Test using Salmonella typhimurium TA1535, TA100, TA1537 and TA98 and Escherichia coli WP2uvrA (pKM1010), with and without metabolic activation using Arochlor -induced rat liver (S9) mix, the test substance did not cause a positive increase in the number of revertants per plate of any of the tester strains in the presence or absence of metabolic activation.