Borate(1-), tris(acetato-.kappa.O)hydro-, sodium, (T-4)-

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP study with Boric acid comparable to OECD guideline with no or minor deviations having no influence on outcome. According to the ECHA guidance document the reliability was changed from 1 to 2 to reflect the fact that the study was conducted with a read-across substance.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1988

Reference 2

Reference Type:

publication

Title:

Responses of the L5178Y tk+/tk- mouse lymphoma cell forward mutation assay: III. 72 coded chemicals

Author:

McGregor, D. et al.

Year:

1988

Bibliographic source:

Environ. Molec. Mutagen. Vol. 12 (1988) 85-154

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

not specified

Principles of method if other than guideline:

Mouse lymphoma L5178Y/tk+/- assay in line with OECD 476, further information in Mitchell et al. (1988), Evaluation of the L5178Y Mouse Lymphoma Cell Mutagenesis Assay: Methods Used and Chemicals Evaluated. Environ. Mol. Mutagen. 12 (Suppl. 13): 1-18.

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Boric acid

EC Number:

233-139-2

EC Name:

Boric acid

Cas Number:

10043-35-3

Molecular formula:

BH3O3

IUPAC Name:

Boric acid

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): Boric acid
- Supplier: Radian Corporation, USA

Method

Target gene:

Thymidine kinase (TK) locus

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: Fischer's medium supplemented with 2 mM l-glutamine, 110 ug/mL sodium pyruvate, 0.05% luronic F68, antibiotics, and heat-inactivated horse serum
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

S9 mix prepared from Aroclor 1254-induced male Fischer 344 rats

Test concentrations with justification for top dose:

Experiment I:
Without S9 mix: 62.5, 125, 250, 500, 1000 µg/mL
With S9 mix: 2000, 3000, 4000, 5000 µg/mL
Experiment II:
Without S9 mix: 1000, 1800, 2600, 3400, 4200, 5000 µg/mL
With S9 mix: 1000, 2000, 3000, 4000, 5000 µg/mL
Experiment III:
Without S9 mix: 1000, 1800, 2600, 3400, 4200, 5000 µg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO (Experiment I, without S9 mix), Fischer Medium

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

methylmethanesulfonate

Remarks:

methylmethanesulfonate (15 µg/mL); 3-methylcholanthrene (2.5 µg/mL)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in suspension

DURATION
- Exposure duration: 4 h
- Expression time (cells in growth medium): 48 h
- Selection time (if incubation with a selection agent): 10-12 day


SELECTION AGENT (mutation assays): trifluorothymidine

NUMBER OF REPLICATIONS: at least 2

DETERMINATION OF CYTOTOXICITY
- Method: loning efficiency; relative total growth

Results and discussion

Test results

Species / strain:

mouse lymphoma L5178Y cells

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

Results:

Nonactivation Trial: 1 Experiment Call: Inconclusive
		Conc.	Cloning	Relative Total	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
		ug/mL	Efficiency	Growth
Vehicle Control	Dimethyl Sulfoxide	0	63	110	119	63	58
			69	102	98	48
			64	115	110	57
			67#	73	130.5	65
Test Chemical	Boric acid	62.5	64	81	124	65	67
			71	75	148	69
		125	50	92	123	83	69
			55	113	93	56
		250	69	61	170	83	72
			52	57	96	62
		500	55	80	135	82	67
			71#	107	110	52
		1000	60	69	131	73	66
			60	71	105	59
Positive Control	Methyl Methane Sulfonate	15	26	29	344	438	435*
			37	28	484	432
Nonactivation Trial: 2 Experiment Call: Negative and Non-Toxic
		Conc.	Cloning	Relative Total	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
		uL/mL	Efficiency	Growth
Vehicle Control	Fischer Medium	0	76	86	72	32	34
			60	108	70	39
			89	123	83	31
			79	83	83	35
Test Chemical	Boric acid	1000	70	109	79	38	38
			72	105	83	39
		1800	75	92	81	36	36
			89#	94	97	36
		2600	71	87	90	42	41
			73	103	90	41
		3400	88#	90	130.5	49	43
			91	82	100	37
		4200	99	86	146	49	48
			107	84	150	47
		5000	95	79	160	56	50
			103	89	135	44
Positive Control	Methyl Methane Sulfonate	15	21	18	257	402	385*
			21	17	226	367
Nonactivation Trial: 3 Experiment Call: Negative and Non-Toxic
		Conc.	Cloning	Relative Total	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
		ug/mL	Efficiency	Growth
Vehicle Control	Fischer Medium	0	95	109	51	18	24
			89	126	84	31
			92	85	67	24
			78	79	54	23
Test Chemical	Boric acid	1800	100	77	66	22	21
			86	92	52	20
		2600	115	78	64	19	22
			113	90	86	25
		3400	78	81	44	19	25
			85	83	78	31
		4200	87	64	68	26	24
			93	80	62	22
		5000	104	62	62	20	22
			112	55	83	25
Positive Control	Methyl Methane Sulfonate	15	54	31	228	140	166*
			42	27	244	192
Induced S9 Trial: 1 Experiment Call: Negative and Non-Toxic
		Conc.	Cloning	Relative Total	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
		ug/mL	Efficiency	Growth
Vehicle Control	Fischer Medium	0	51	76	141	92	67
			94	109	136	48
			78	107	121	52
			81	108	185	76
Test Chemical	Boric acid	2000	62	92	107	57	51
			70	117	95	46
		3000	87	115	156	60	85
			56	43	184	110
		4000	98	116	155	53	52
			83	110	128	52
		5000	89	103	140	52	53
			74	90	120	54
Positive Control	3-Methylcholanthrene	2.5	66	72	340	171	182*
			62	67	358	193
Induced S9 Trial: 2 Experiment Call: Negative and Non-Toxic
		Conc.	Cloning	Relative Total	Mutant Colonies	Mutant Frequency	Avg Mutant Frequency
		ug/mL	Efficiency	Growth
Vehicle Control	Fischer Medium	0	70	87	175	84	90
			87#	103	223.5	85
			96	104	285	99
			80	106	222	92
Test Chemical	Boric acid	1000	83#	99	211.5	85	83
			73	90	176	81
		2000	94#	90	278	99	98
			80	88	235	98
		3000	79	71	263	111	109
			80	100	257	107
		4000	73#	87	217.5	99	95
			100	77	273	91
		5000	64#	57	175.5	92	114
			57	65	230	136
Positive Control	3-Methylcholanthrene	2.5	59	34	867	488	536*
			45#	38	787	583

* = significant responses
r = rejected value due to quality control criteria
# = reduced sample size because of the loss of one culture dish due to contamination

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

No significant increase in mutation of the TK locus in mouse lymphoma L5178Y cells was induced by Boric acid up the a concentration of 5000 µg/mL with and without metabolic activation by S9 mix.

Executive summary:

Boric acid was tested for inducing gene mutation in mammalian cells in a GLP study performed according to NTP protocol which is comparable to OECD guideline. Well maintained mouse lymphoma L5178Y cells were treated with boric acid up concentration of 5000 µg/mL with and without metabolic activation by a S9 mix for 4 hours. Since no toxicity and no increase in frequency was observed, boric acid was regarded to be non-mutagenic in mammalian cells.