Reaction mass of sodium 4-hydroxybenzenesulfonate and disodium 4-hydroxybenzene-1,3-disulfonate and sodium sulfate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In vitro gene mutation in bacteria (Ames test): negative

In vitro micronucleus test: negative

In vitro gene mutation in mammalian cells: in progress

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

Negative

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Ames test

This study was performed to evaluate the mutagenic activity of the test substance using the bacterial reverse mutation test on five histidine deficient mutant tester strains of Salmonella typhimurium (i.e., TA1537, TA1535, TA98, TA100, and TA102).

The test item was tested in two independent experiments in the absence and presence of metabolic activation. Bacterial cultures were exposed to the test item at 8 concentration levels (two plates/concentration) ranging from 1.5 to 5000 µg/plate in the initial toxicity-mutation test, using the plate incorporation method.

Normal bacterial background lawn was observed up to the concentration of 5000 µg/plate, in all tester strains (TA1537, TA1535, TA98, TA100, and TA102) in the absence and presence of the metabolic activation system (5% v/v S9 mix).

No increase in the number of revertant colonies (no mutagenic effect) was observed in the absence and presence of the metabolic activation system (5% v/v S9 mix) in any tester strain. To confirm the negative results obtained in the initial toxicity mutation test, the confirmatory mutation test was conducted, using the plate incorporation method with an increased S9 concentration, i.e., 10% v/v S9 mix and concentration spacing modification.

Bacterial cultures were exposed to the test substance at 6 concentration levels (three plates/concentration) ranging from 156.25 to 5000 µg/plate for tester strains TA1537, TA1535, TA98, TA100, and TA102 in the absence and presence (10 % v/v S9 mix) of the metabolic activation. The revertant colonies were scored after 48 hours of incubation at 37 ± 1 °C.

The test item did not induce any significant increase in the number of revertants, in trials with and without S9 mix, in any tester strain. Values for the negative control were within the historical control ranges of the laboratory. Positive controls showed an increase in the number of revertant colonies, demonstrating the efficiency of the test system.

All criteria for a valid study were met. Based on the results of this study, under specified experimental conditions, the test substance is concluded to be non-mutagenic in the Bacterial Reverse Mutation Test using Salmonella typhimurium.

In vitro micronulceus test

The evaluation of the chromosome damaging potential of In Vitro Mammalian Cell Micronucleus test of the test substance in Human Peripheral Blood Lymphocytes.

The substance was tested in two independent experiments, in the absence and presence of metabolic activation (2% v/v S9 mix), at selected concentrations based on results of cytotoxicity test. In the main study, human peripheral blood lymphocyte cultures were exposed to the test item at 6 concentrations from 62.5 to 2000 µg/mL (two cultures/dose level) in culture medium, in the absence and presence of metabolic activation system. The main study was conducted in two phases with lymphocytes exposed for 4 hours (with and without metabolic activation) as Phase I, and for 24 hours exposure (without S9) as Phase II. Following the consideration of the replicative index data, three concentrations of the test item were selected for micronucleus frequency analysis.

The test item did not induce either a statistically significant or biologically relevant increase in the number of binucleated cells with micronuclei, in the absence and presence of the metabolic activation, in either independently conducted experiment. The positive controls (cyclophosphamide and vinblastine) induced a statistically significant increase in the number and frequency of micronucleated binucleate cells and all criteria for a valid study were met.

From results of this study, it is concluded that the test substance did not induce micronuclei in isolated cultured human peripheral blood lymphocytes, when tested up to the concentration of 2000 µg/mL short term Phase I (in the absence and presence of metabolic activation (2% v/v S9 mix)) and in absence of metabolic activation at 2000 µg/mL at 24 h (long term -Phase II), under the described experimental conditions.

Additional information from genetic toxicity in vivo:

There are two in vivo mouse micronucleus studies for the hydrotropes – sodium cumene sulphonate (CAS 28348-53-0) (Sasol, 1992) and calcium xylene sulphonate (CAS 28088-63-3) (Ruetgers-Nease, 1994). Both are GLP-compliant Guideline mouse micronucleus studies with full documentation.  The Sasol study was an oral dose of 4467 mg/kg bw and the Ruetgers-Nease study was an IP injection exposure of up to 580 mg/kg bw. All studies conclude the test substances were not mutagenic in these assays.

 

Justification for classification or non-classification

No conclusion on the mutagenicity of the substance can be currently drawn as the the gene mutation test in mammalian cells is still in progress