Potassium bromate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from-to

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is considered acceptable for the purpose of registration under REACH. The method followed that described in the OECD Guidelines for Testing of Chemicals (Adopted: 4 April 1984) No 471 "Bacterial Reverse Mutation Test".

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Deviations:

no

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Potassium bromate

EC Number:

231-829-8

EC Name:

Potassium bromate

Cas Number:

7758-01-2

Molecular formula:

BrHO3.K

IUPAC Name:

potassium bromate

Constituent 2

Reference substance name:

7758-01 -2

IUPAC Name:

7758-01 -2

Details on test material:

Supplier: Aldrich
Purity > 99 %

Method

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535

Additional strain / cell type characteristics:

other: mutations in the histidine operon

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1537

Additional strain / cell type characteristics:

other: mutations in the histidine operon

Species / strain 3

Species / strain / cell type:

S. typhimurium TA 98

Additional strain / cell type characteristics:

other: mutations in the histidine operon

Species / strain 4

Species / strain / cell type:

S. typhimurium TA 100

Additional strain / cell type characteristics:

other: mutations in the histidine operon

Species / strain 5

Species / strain / cell type:

S. typhimurium TA 97

Additional strain / cell type characteristics:

other: mutations in the histidine operon

Metabolic activation:

with and without

Metabolic activation system:

rat liver homogenate (S9 mix) with standard co-factors with metabolic activation (Aroclor)

Test concentrations with justification for top dose:

three series using 0, 33, 100, 333, 1000, 3333, 6667, and 10000 µg/plate

Vehicle / solvent:

H2O

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

sodium azide

Controls 2

Positive controls:

yes

Positive control substance:

9-aminoacridine

Controls 3

Positive controls:

yes

Positive control substance:

other: 4-nitro-o-phenylenediamine

Controls 4

Positive controls:

yes

Positive control substance:

mitomycin C

Controls 5

Positive controls:

yes

Positive control substance:

other: methyl methanesulfonate

Controls 6

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with S9

Details on test system and experimental conditions:

Bacterial strains

Salmonella typhimurium strains TA97, TA98, TA100, TA102, TA104, TA153.5, TA1.537 and TA1.538 were obtained from Dr. Bruce Ames (University of California, Berkeley) and stored as recommended [Maron and Ames,1981]. Cultures were grown at 37°C overnight, with shaking, in Oxoid #2 broth, or in defined minimal medium supplemented with biotin (0.8 µg/ml) and histidine (40 µgiml). The phenotypes of the strains were analyzed at the time of their use in mutagenicity assays.

Preparation of Liver S-9 Fractions

The S-9 (9,000 x g supernatant) fractions of Aroclor 1254-induced, male Sprague-Dawley rat and male Syrian hamster livers were prepared as described previously [Haworth et al., 1983]. The S-9 mixes were prepared immediately prior to use and contained either 10% or 30% S-9; occasionally, 5% S-9 was also used. The specific S-9 concentrations used are indicated in the Appendix 2 tables. All chemicals were tested in the absence of metabolic activation, and with rat and hamster S-9 fractions.

Experimental Protocols

The preincubation procedure was performed as described previously [Haworth et al., 1983], with some differences, as described below.
The test chemical (0.05 ml), overnight culture of Salmonella (0.10 ml), and S-9 mix or buffer (0.50 ml), were incubated at 37°C, without shaking, for 20 min. The top agar was added and the contents of the tubes were mixed and poured onto the surface of petri dishes containing Vogel-Bonner medium [Vogel and Bonner, 1956].
Histidine-independent (his+) colonies arising on these plates were counted following two days incubation at 37°C. Plates were machine counted (New Brunswick; Artek) unless precipitate was present which interfered with the count, or the color of the test chemical on the plate reduced the contrast between the colonies and the agar. At the discretion of the investigators, plates with low numbers of colonies, containing precipitated test chemical, or having excessivelyreduced contrast because of chemical color, were counted by hand.

Evaluation criteria:

1) mutagenic response: a dose-related, reproducible increase in the number of revertants over background, even if the increase was less than twofold;
2) nomutagenic response: when no increase in the number of revertants was elicited by the chemical;
3) questionable response: when there was an absence of a clear-cut dose-related increase in revertants; when the dose-related increases in the number of revertants were not reproducible; or when the response was of insufficient magnitude to support a determination of mutagenicity.

The initial determination of mutagenic, nonmutagenic, or equivocal was made by the testing laboratory; the final determination was made by the project officer (E.Z.). The chemicals were decoded by the chemical repository (Radian Corporation) only after the mutagenicity or nonmutagenicity of the chemicals had been determined.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

ambiguous

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 97

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 6

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

for details see publication

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Dose	TA 100
	NA	30 % HLI	30 % RLI
	?	?	?
0	145±6.7	159±3.5	150±6.4
33
100	114±9.0	158±4.6	157±7.6
333	153±2.1	158±11.2	122±14.7
1000	148±8.5	226±13.5	180±10.1
3333	177±10.0	148±21.5	210±2.3
6667	184±7.8	162±11.7	182±13.5
10000	189±6.1	175±14.2	179±10.7
Control	704±52.1	957±66.4	902±38.9

Dose	TA 1535
	NA	10 % HLI	10 % HLI	30 % HLI	30 % HLI
	-	+	+	+	-
0	27±0.6	11±1.8	11±2.2	13±3.4	15±2.0
33
100	18±1.5				18±0.6
333	24±3.5	13±2.5	17±4.9	15±2.4	17±0.3
1000	32±1.2	16±2.2	18±2.6	18±1.8	22±3.3
3333	32±3.7	23±3.8	14±2.7	21±1.7	26±0.9
6667		34±1.2	26±0.6	28±1.9
10000	28±2.9	28±1.5	21±0.9	13±1.5	19±1.2s
Control	532±7.7	50±1.0	910±38.4	190±7.3	493±180.8

Dose	TA 1535
	10 % RLI	10 % RLI	30 % RLI	30 % RLI
	+	-	?	+
0	11±2.6	16±3.5	14±1.9	13±1.8
33
100				16±2.3
333	12±0.3	16±2.8	16±0.9	20±2.7
1000	17±1.9	16±1.2	18±3.0	24±0.9
3333	31±0.9	19±6.5	23±3.1	27±1.8
6667	36±4.1	25±2.7	27±3.1
10000	36±3.0	21±1.7	16±3.5	32±2.3
Control	282±14.8	166±15.0	142±0.9	222±15.6

Dose	TA 1537
	NA	10 % HLI	30 % HLI	10 % RLI	30 % RLI
	-	-	-	-	-
0	17±3.6	16±1.9	16±2.9	20±1.2	21±4.3
33
100
333	24±0.7	17±2.9	19±1.0	21±0.9	18±3.8
1000	19±2.3	22±4.7	21±0.7	23±0.7	26±3.2
3333	14±2.3	18±2.6	21±2.1	23±3.3	18±3.5
6667	13±3.7	12±0.9	20±1.2	22±2.8	17±4.9
10000	15±1.2	15±1.2	13±1.2	16±2.6	13±0.7
Control	77±5.7	428±30.1	128±5.2	940±12.2	175±5.4

Dose	TA 97
	NA	NA	10 % HLI	30 % HLI	30 % HLI	10 % RLI	10 % RLI	30 % RLI	30 % RLI
	+	+W	+W	+W	+W	+W	+	+W	+W
0	110±4.4	105±2.9	233±6.7	130±6.0	161±14.1	182±17.8	107±2.1	119±5.4	155±5.4
33					171±7.7				176±8.6
100	125±6.7	100±4.9		143±8.0	183±3.2			159±5.7	152±4.9
333	151±11.2	165±11.0	256±11.8	205±15.0	223±13.7	271±10.9	118±3.8	173±5.9	208±7.5
1000	219±14.2	223±11.3	265±7.5	205±7.5	257±13.0	284±8.3	204±25.8	216±8.7	270±8.5
3333	261±1.0	179±7.4	386±16.6	201±18.2	270±12.5	350±3.1	262±7.8	139±25.9	249±2.3
6667		92±10.6	340±10.7			331±1.5	205±21.1
10000	0±0.0		334±26.0s	57±7.7s		256±20.3s	178±16.0	0±0s
Control	4230±224	94±3.3	804±19.5	1592±34.9	1478±6.7	3178±123		724±10.7	2102±81.4

Dose	TA 98
	NA	30 % HLI	30 % RLI
	-	-	-
0	26±4.3	32±4.0	30±2.4
33
100	22±5.4	42±2.3	37±2.7
333	25±0.7	41±1.8	39±2.0
1000	26±2.5	34±2.1	33±5.7
3333	32±1.9	37±5.0	45±1.8
6667	36±3.2	28±1.5	41±4.3
10000	25±0.7	23±3.3	35±0.6
Control	152±18.0	766±39.1	314±24.6

Abbreviations
NA, not activated
HLI, Aroclor 1254-induced hamster liver S-9
RLI, Aroclor 1254-induced rat liver S-9
s, slight clearing of background lawn
t, complete clearing of background lawn (colonies not counted)
p, precipitate present in plates
x, precipitate present with toxicity
+, mutagenic
+W, weakly mutagenic
?, questionable response
- , nonmutagenic.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
positive with and without metabolic activation

With and without addition of S9 mix as the external metabolizing system, the test item was mutagenic under the experimental conditions described.

Executive summary:

Purpose

The purpose of this assay was to provide information on possible health hazards for the test material and serve as a rational basis for risk assessment to the genotoxic potential of the test item in man.

Study Design

The investigations for the mutagenic potential were performed using Salmonella typhimurium tester strains TA 97, TA98, TA 100, TA 1535 and TA 1537. Further details on study design are published in E. Zeiger et al., Environmental & Molecular Mutagenesis 1992, 19 Suppl 21, 2-141.

Results

The test item dissolved in water was tested at concentrations ranging from 33 up to 10000 µg/plate. Precipitation of the test material on the agar plates occurred as indicated in the tables enclosed. Toxicity to the bacteria was not observed.

Each treatment with positive controls led to a clear increase in revertant colonies, thus, showing the expected reversion properties of all strains and good metabolic activity of the S9 mix used.

The increase in the number of revertant colonies observed for TA 1535 with metabolic activation and TA 97 with and without metabolic activation was significant and shows dose response relationship thus indicating that the test item was mutagenic under the described experimental conditions.

Conclusion

With and without addition of S9 mix as the external metabolizing system, the test item was mutagenic under the experimental conditions described.