Potassium bromide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1988

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: EPA FIFRA 82-2

Deviations:

yes

Remarks:

Salmonella typhimurium TA 1538 was used instead of TA 102 or Escherichia coli WP2 uvrA or WP2 uvrA (pKM101).

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

Salmonella typhimurium TA 1538 was used instead of TA 102 or Escherichia coli WP2 uvrA or WP2 uvrA (pKM101).

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Sodium bromide

EC Number:

231-599-9

EC Name:

Sodium bromide

Cas Number:

7647-15-6

IUPAC Name:

sodium bromide

Details on test material:

- Name of test material (as cited in study report): Sodium Bromide
- Description: White granular powder
- Analytical purity: 98 %
- Lot/batch No.: 1402
- Stability under test conditions: Stability under storage conditions not stated.
- Storage condition of test material: Stored at room temperature.
Potassium bromide is an inorganic salt that dissociates to its composite ions in aqueous solutions at environmental pH and temperature. Comparison of the available data on the various bromide salts have shown that the bromide ion is the relevant ion for determination of the toxicological profile with simple cations such as potassium, sodium or ammonium, that are ubiquitous in nature, having little or no influence on the bromide ion properties. It is therefore justified to read-across data from other inorganic bromide salts to potassium bromide.

Method

Target gene:

other: not applicable

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:

S. typhimurium TA 1538

Metabolic activation:

with and without

Metabolic activation system:

S9 mix: prepared from Sprague-Dawley rats after stimulation with a single intraperitoneal injection of 500 mg /kg Aroclor 1254 (200 mg/ml in Arachis oil) five days prior to sacrifice

Test concentrations with justification for top dose:

Dose range finding: 5, 50, 500, 5000 µg/plate;
Mutation test: 50, 150, 500, 1500 and 5000 µg/plate

Vehicle / solvent:

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

Controls

Untreated negative controls:

yes

Remarks:

solvent (water)

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: as stated under remarks

Remarks:

Positive control substances used: With metabolic activation: 2-Aminoanthracene (all strains with S9 mix) No metabolic activation: 2-Nitrofluorene (TA 1538, TA 98), 9-Aminoacridine (TA 1537), N-Ethyl-N-nitro-N-nitrosoguanidine (TA 1535, TA 100)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)


DURATION
- Preincubation period: not applicable, only a plate-incorporation test was performed
- Exposure duration: 72 hours



SELECTION AGENT (mutation assays): histidine deficient agar

NUMBER OF CELLS EVALUATED: n.a.; 2 x 10E8 bacterial cells/0.1 mL were used in the test per plate and dose level

NUMBER OF REPLICATIONS: three plates were prepared per tester strain.



DETERMINATION OF CYTOTOXICITY
- Method: relative total growth


OTHER:
A preliminary toxicity test was performed for each bacterial strain used. The highest concentration used was 5 g of sodium bromide dissolved in 1 ml of solvent. Three 10-fold serial dilutions were also tested.
Per tester strain five concentrations of sodium bromide were tested and three bottles were used at each dose level.
The mean number of revertant colonies for all treatment groups was compared with those obtained for negative and positive control groups. The effect of metabolic activation was assessed by comparing the results obtained both in the presence and absence of the liver microsomal fraction for each treatment group. A compound was deemed to provide evidence of mutagenic potential if a statistically significant dose-related increase in the number of revertant colonies of at least twice the concurrent solvent control was obtained in two separate experiments

Evaluation criteria:

The reliability and sensitivity of the test system was confirmed by parallel testing of positive and negative controls.

A compound was deemed to provide evidence of mutagenic potential if a statistically significant dose-related increase in the number of revertant colonies of at least twice the concurrent solvent control was obtained in two separate experiments.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

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 2

Species / strain:

S. typhimurium TA 1538

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

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Table A6.6.1/02-1:     Results of the in vitro Gene Mutation Assay (Plate Incorporation Test) with Sodium Bromide
Concentration [µg per plate]	Mean number of mutant cells*
without metabolic activation
Dose level [µg/plate]	TA 1535		TA 1537		TA 1538		TA 98		TA 100
	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2
5000	10	12	10	10	14	12	19	25	115	121
1500	13	13	9	11	13	12	25	23	120	97
500	13	15	14	9	16	14	20	21	115	109
150	13	12	13	10	12	9	24	24	131	116
50	10	11	10	8	14	11	23	25	131	107
0	12	10	12	10	13	10	27	19	121	104
solvent	15	15	14	9	12	11	23	29	129	110
ENNG 3 - 5	161	80	-	-	-	-	-	-	338	282
9-AC 80	-	-	x	1073	-	-	-	-	-	-
NF 1 - 2	-	-	-	-	57	62	106	112	-	-
with metabolic activation
Dose level [µg/plate]	TA 1535		TA 1537		TA 1538		TA 98		TA 100
	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2	Test 1	Test 2
5000	10	12	10	10	13	9	18	21	128	110
1500	12	14	10	9	11	10	28	24	129	91
500	8	12	11	12	12	12	17	22	133	113
150	11	12	9	8	13	10	22	23	135	130
50	9	12	13	11	10	10	23	29	133	122
0	11	13	14	10	16	11	21	21	145	110
solvent	13	17	10	9	15	11	27	23	131	122
2-AA 0.5 - 2	145	126	83	58	147	127	181	118	471	445

*:             mean from three individual plates

X:            too many colonies for counting

ENNG:   N-ethyl-N-nitro-N-nitrosoguanidin: 5 µg/plate for TA 1535, 3 µg/plate for TA 100

9-AC:      9-aminoacridine: 80 µg/plate for TA 1537

AA:         2-aminoanthracene: 2 µg/plate for TA 1535 and TA1537; 0,5 µg/plate for TA 1538 and TA 98; 1µg/plate for TA 100

NF:         2-nitrofuorene: 2 µg/plate for TA 1528, 1 µg/plate for TA 98

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

No evidence for mutagenic potential of sodium bromide was obtained in this bacterial test system at the dose levels used.

Executive summary:

Materials and Methods

The toxicity potential of sodium bromide (98 %) was examined in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100, TA 1538 (EPA FIFRA 84-2).

Tester strains were treated with 50, 150, 500, 1500 and 5000 µg/plate sodium bromide in the presence and absence of a metabolic activation system (S9 mix) in triplicate each and revertant colonies were counted after 72-hour incubation time.

No cytotoxicity (clearing of background lawn) or precipitation was observed up to and including the maxium concentration of 5 mg/plate.

The reliability and sensitivity of the test system was confirmed by parallel testing of positive and negative controls.

A compound was deemed to provide evidence of mutagenic potential if a statistically significant dose-related increase in the number of revertant colonies of at least twice the concurrent solvent control was obtained in two separate experiments

Results and Diskussion

Sodium bromide was not toxic towards all tester strains in the dose range finding study up to and including a concentration of 5000 µg/plate. Therefore, 5000 µg/plate was chosen as the top dose level in the mutation test.

No substantial increase in revertant colony numbers of any of the five tester strains when compared with revertants in solvent controls were observed following treatment with sodium bromide at any dose level, either in the presence or in the absence of metabolic activation (S9 mix).

Positive controls were shown to have significantly increased the number of revertants per plate and results obtained were within the ranges expected for each bacterial strain and activation condition.