Reaction mass of sulphuric acid, hydrogen peroxide and peroxomonosulphuric acid

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:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The reaction mass of sulphuric acid, hydrogen peroxide and peroxomonosulphuric acid is predominantly sulphuric acid (>80%). Although all constituents of the reaction mass contribute towards and are essential for the desired technical effects of the range, it is considered acceptable to read-across to data on sulphuric acid. This because significant toxicological effects are likely to be masked in the multi-constituent substance by its corrosive nature and so it considered appropriate to read across to the mean constituent, sulphuric acid, when considering in vitro gene mutation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across data matrix under 'Attached background material' below.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across data matrix under 'Attached background material' below.

4. DATA MATRIX
See read-across data matrix under 'Attached background material' below.

Data source

Reference

Reference Type:

publication

Title:

Sublethal pH decrease may cause genetic damage to eukaryotic cell: a study on sea urchins and Salmonella typhimurium

Author:

Cipollaro M, Corsale G, Esposito A, Ragucci E, Staiano N, Giordano GG & Pagano G

Year:

1986

Bibliographic source:

Teratogenesis, Carcinogenesis and Mutagenesis, 6: 275-287

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

no

Remarks:

Study pre-dates GLP

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Sulphuric acid

EC Number:

231-639-5

EC Name:

Sulphuric acid

Cas Number:

7664-93-9

Molecular formula:

H2O4S

IUPAC Name:

Sulphuric acid

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): H2SO4

Method

Target gene:

Histidine

Species / strain

Species / strain / cell type:

other: TA 97; TA 98; TA100; TA102; TA1535

Metabolic activation:

with and without

Metabolic activation system:

S9 fraction prepared from liver homogenates of Sprague-Dawley rats induced with Aroclor 1254 (data not reported)

Test concentrations with justification for top dose:

- Effect was measured in terms of pH (4.0, 5.0, 5.5, 6.0, 6.3, 6.8, 7.0, 7.4, 7.8, 8.0, 9.0)

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: daunomycin

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Details on test system and experimental conditions:

- Salmonella typhimurium tester strains were obtained from Dr B N Ames (University of California, Berkeley, CA)
- The standard plate incorporation assay was carried out according to the procedure developed by Ames and Maron and Ames et al to measure spontaneous reversion rate of tester strains in histidine-free media.
- The effect of pH changes on bacterial reversion rate was evaluated by adoptin two modifications of the standard plate incorporation assay.
- Preincubation of bacteria with buffer solutions at pH values ranging from 4 to 9 was carried out using H3PO4, H2SO4 and their sodium salts.
- Cultures of the tester strains (o.1 mL) were mixed with 0.5 mL of the buffer solutions, incubated at 37 °C for one hour, and then added to the top agar, plated on Vogel-Bonner medium plates and the plates were incubated at 37 °C for 60 hours.
- For agar plate incorporation, a modified Vogel-Bonner medium was prepared using a MgSO4.7H2O (10 g), citric acid.H2O (100 g), K2HPO4 (500 g) and NaNH4HPO4.4H2O (175 g) in 670 mL distilled water, and 10 mL was added to 220 mL of distilled water. The diluted solution was then adjusted to final pH with 10N NaOH.
- After sterilisation, 220 mL agar solution (45 g agar per 1,320 mL water) and 50 mL of 5 % dextrose was added to the 230 mL of pH-adjusted salt solution. Plates were then poured with 25 mL of the above media in each.
- The pH was confirmed for each plate type by using a surface pH electrode (Ingold, Switzerland).
- The pH of the total plate assay system were assumed to be the same as that of the initial base agar.
- All the plate types were prepared with enough NaCl added to the medium to result in an ionic strength identical to that of the pH 7.0 controls.
- Addition of S9 fraction was scheduled for some experiments in order to complete the bioassay protocol as well as to check a previously reported detoxifying action of S9 for some inorganics.

Evaluation criteria:

- The number of revertants per plate were counted

Results and discussion

Test results

Species / strain:

other: TA 97; TA 98; TA100; TA102; TA1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

observed at pH 5

Vehicle controls validity:

not applicable

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

- The reversion properties and specificity of each strain were confirmed by testing methylmethanesulphonate, daunomycin and sodium azide in the standard plate incorporation assay.
- Incubation of S. typhimurium tester strains with different buffer solutions at pH values ranging from 5.5 to 9 had no effect on the bacterial reversion rates.
- Appearance of survivors suggested that acidification of the incubation mixture to pH 5.0 produced toxic effects on bacteria.
- At lower pH values, complete bacterial death was observed.
- The same negative results were obtained by using the base agar plates at different pH values.
- Results were unchanged by addition of S9 fraction (data not reported)

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

JUSTIFICATION FOR USE OF READ-ACROSS DATA

 

See comparison of overall physico-chemical and toxicity profiles for target and source chemicals in the data matrix (attached).

EFFECT OF pH ON TESTER STRAINS

Revertants per plate
	pH
Strain	4.0	5.0	5.5	6.0	6.3	6.8	7.0	7.4	7.8	8.0	9.0
TA 97	**	*	75	79	83	82	85	86	82	83	79
TA 98	**	*	29	28	31	30	35	40	32	27	31
TA 100	**	*	102	107	115	117	103	115	131	101	124
TA 102	**	*	182	185	182	178	175	195	197	183	182
TA 1535	**	*	15	11	13	11	15	16	11	17	12
*	Small colonies without bacterial lawn
**	Complete bacterial killing

Applicant's summary and conclusion

Conclusions:

Interpretation of results:
negative

No effects were detectable with or without metabolic activation in Salmonella typhimurium strains TA 97, TA 98, TA 100, TA 102 and TA 1535, at concentrations up to those causing cytotoxicity.