Potassium tetrahydroborate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Under physiological conditions, potassium tetrahydroborate decomposes to boric acid and borate salt, respectively. Boric acid and borax and thus potassium tetrahydroborate as well can be stated as non-mutagenic under the test conditions.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

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:

Materials and methods are described in detail. The test procedure follows the general procedure for the AMES-Test. Peer-reviewed publication that meets basic scientific principles.

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are described in detail. The test procedure follows the general procedure for the AMES-Test. Peer-reviewed publication that meets basic scientific principles.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

Boric acid and Borax were used as test materials.

Target gene:

Histidine

Species / strain / cell type:

S. typhimurium TA 98

Species / strain / cell type:

S. typhimurium TA 100

Metabolic activation:

with and without

Test concentrations with justification for top dose:

0.01, 0.1, 1, 10, 100 µg/plate for boric acid and borax
In preliminary assays, borax and boric acid showed mutagenic activity at a level of l μglplate; therefore, a range of doses from 0.01 to 100 μg/plate was chosen for study.

Vehicle / solvent:

water

Untreated negative controls:

yes

Remarks:

spontaneous revertants

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

sodium azide

benzo(a)pyrene

Details on test system and experimental conditions:

The bacterial strains (T A98 and TA 100) were acquired from Dr. B. N. Ames (Biochemistry Department, University of California, Berkeley, CA).

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Table 1. Response of Salmonella test strains to boron and positive control compounds with and without S-9 activation*

Material	Conc. (µg/plate)	TA98 with S-9	TA98 without S-9	TA100 with S-9	TA100 without S-9
Borax	0.01	34±4	30±2	92±11	107±35
Borax	0.1	29±1	30±2	91±6	98±16
Borax	1	34±7	42±4	116±7	81±5
Borax	10	37±8	32±5	121±24	78±12
Borax	100	43±6	31±5	113±8	87±9
Boric acid	0.01	37±3	29±7	104±23	122±14
Boric acid	0.1	35±6	29±3	103±12	112±15
Boric acid	1	44±4	32±11	108±18	126±10
Boric acid	10	43±4	42±1	126±3	127±9
Boric acid	100	40±9	23±7	108±11	127±3
Benzo[a]pyrene	2	142±22	36±8	327±19	125±9
Benzo[a]pyrene	4	322±17	31±4	691±7	111±15
Benzo[a]pyrene	6	540±57	26±3	780±59	110±21
Sodium azide	1	54±6	39±4	101±69	481±7
Sodium azide	5	43±6	35±6	395±21	896±23
Sodium azide	10	36±12	46±13	786±130	986±50
Spontaneous revertants	-	39±1	37±8	111±23	97±11

* Data are expressed as number of revertant colonies per plate per strain (means ± SD).

Conclusions:

Boric acid and borax can be stated as non-mutagenic under the test conditions.

Executive summary:

The boron compounds failed to produce a mutagenic response in either of the test strains. The revertant colonies produced per plate (23 to 44 and 78 to 127 for TA98 and TA 100, respectively) were not significantly different from the rate of spontaneous revertants for both strains tested.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

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

Adequacy of study:

key study

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:

Under physiological conditions, potassium tetrahydroborate decomposes to boric acid and borate salt, respectively. Thus the genetic toxicity of boric acid should be determined to evaluate the mutegenic potential of potassium tetrahydroborate.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are described in detail. The test procedure follows the general procedure for the AMES-Test.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

Boric acid and Borax were used as test materials.

Target gene:

Histidine

Species / strain / cell type:

S. typhimurium TA 98

Species / strain / cell type:

S. typhimurium TA 100

Metabolic activation:

with and without

Test concentrations with justification for top dose:

0.01, 0.1, 1, 10, 100 µg/plate for boric acid and borax
In preliminary assays, borax and boric acid showed mutagenic activity at a level of l μglplate; therefore, a range of doses from 0.01 to 100 μg/plate was chosen for study.

Vehicle / solvent:

water

Untreated negative controls:

yes

Remarks:

spontaneous revertants

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

sodium azide

benzo(a)pyrene

Details on test system and experimental conditions:

The bacterial strains (T A98 and TA 100) were acquired from Dr. B. N. Ames (Biochemistry Department, University of California, Berkeley, CA).

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Table 1. Response of Salmonella test strains to boron and positive control compounds with and without S-9 activation*

Material	Conc. (µg/plate)	TA98 with S-9	TA98 without S-9	TA100 with S-9	TA100 without S-9
Borax	0.01	34±4	30±2	92±11	107±35
Borax	0.1	29±1	30±2	91±6	98±16
Borax	1	34±7	42±4	116±7	81±5
Borax	10	37±8	32±5	121±24	78±12
Borax	100	43±6	31±5	113±8	87±9
Boric acid	0.01	37±3	29±7	104±23	122±14
Boric acid	0.1	35±6	29±3	103±12	112±15
Boric acid	1	44±4	32±11	108±18	126±10
Boric acid	10	43±4	42±1	126±3	127±9
Boric acid	100	40±9	23±7	108±11	127±3
Benzo[a]pyrene	2	142±22	36±8	327±19	125±9
Benzo[a]pyrene	4	322±17	31±4	691±7	111±15
Benzo[a]pyrene	6	540±57	26±3	780±59	110±21
Sodium azide	1	54±6	39±4	101±69	481±7
Sodium azide	5	43±6	35±6	395±21	896±23
Sodium azide	10	36±12	46±13	786±130	986±50
Spontaneous revertants	-	39±1	37±8	111±23	97±11

* Data are expressed as number of revertant colonies per plate per strain (means ± SD).

Conclusions:

Under physiological conditions, potassium tetrahydroborate decomposes to boric acid and borate salt, respectively. Boric acid and borax and thus potassium tetrahydroborate as well can be stated as non-mutagenic under the test conditions.

Executive summary:

The boron compounds failed to produce a mutagenic response in either of the test strains. The revertant colonies produced per plate (23 to 44 and 78 to 127 for TA98 and TA 100, respectively) were not significantly different from the rate of spontaneous revertants for both strains tested.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)