Trilithium nitride

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

No mutagenic potential was observed in a bacterial reverse mutation assay conducted with ammonia. A mouse lymphoma assay with the source substance LiOH*H2O was also negative. The target substance can therefore regarded as non mutagenic.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-01-20 to 2010-07-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1997

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase (TK)

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

The indicator cell used for this study was the L5178Y mouse lymphoma cell line that is heterozygous at the TK locus (+/-). The particular clone (3.7.2C) used in this assay is isolated by Dr. Donald Clive (Burroughs Wellcome Company, Research Triangle Park, NC).

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9 mix

Test concentrations with justification for top dose:

12.5, 25, 50 100 and 200 ug/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Aqua ad iniectabilia

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without S9-mix

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

Remarks:

with S9-mix

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

ASSAY WITHOUT METABOLIC ACTIVATION
The cells for the experiments were obtained from logarithmically growing laboratory stock cultures and were seeded into a series of tubes at 1 x 107 cells per tube. The cells were pelleted by centrifugation, the culture medium was removed, and the cells were resuspended in a final volume of 20.0 mL of treatment medium that contained 5% heat inactivated fetal bovine serum. The dosed tubes were closed, vortexed and placed on a roller drum at approx. 37 degree C at 10 - 15 rpm for an exposure period of 3 hours. The cells were washed and resuspended in growth medium.
Cell densities were adjusted to 2 x 105/mL and the cells were plated for survival and incubated for the expression period in parallel, i.e. an aliquot of the cells was diluted to 8 cells/mL and 0.2 mL of each culture were placed in two 96 well microtiter plates (192 wells, averaging 1.6 cells/well) and incubated for 1 week at 37 ± 0.4 degree C whereas the rest of the cells was incubated for 2 days at 37 ± 0.4 degree C for the expression period.
The cells for the plating of survival were counted after 1 week and the number of viable clones was recorded. The cells in the expression period were maintained below 106 cells per mL and a minimum of 4 concentration levels plus positive and negative control was selected for 5-trifluoro-thymidine (TFT) resistance.
At the end of the expression period, the selected cultures were diluted to 1 x 104 cells/mL and plated for survival and TFT resistance in parallel (plating efficiency step 2). The plating for survival was similar to the above described method. For the plating for TFT resistance, 3 μg/mL TFT (final concentration) were added to the cultures and 0.2 mL of each suspensions placed into four 96-well microtiter plates (384 wells, averaging 2 x 103 cells/well). The plates were incubated for 12 days at 37 ± 0.4 degree C and wells containing clones were identified microscopically and counted.
In addition, the number of large and small colonies was recorded with an automated colony counter that can detect colony diameters equal or greater than 0.2 to 0.3 mm. Large colonies are defined as >= 1/3 and small colonies < 1/3 of the well diameter of 6 mm.

ASSAY WITH METABOLIC ACTIVATION
The activation assay is often run concurrently with the non-activation assay; however, it is an independent assay performed with its own set of solvent and positive controls. In this assay, the above-described activation system was added to the cells together with test item.

Evaluation criteria:

The minimum criterion considered necessary to demonstrate mutagenesis for any given treatment was a mutant frequency that was >= 2 times the concurrent background mutant frequency. The observation of a mutant frequency that meets the minimum criterion for a single treated culture within a range of assayed concentrations was not sufficient evidence to evaluate a test item as a mutagen.
A concentration-related or toxicity-related increase in mutant frequency should be observed.
The ratio of small : large colonies will be calculated from the results of the determination of small to large colonies.
If the test item is positive, the ratio of small to large colonies for the test item will be compared with the corresponding ratios of the positive and negative controls. Based on this comparison, the type of the mutagenic properties (i.e. basepair substitutions, deletions or large genetic changes frequently visible as chromosomal aberrations) of the test item will be discussed.
A test item is evaluated as non-mutagenic in a single assay only if the minimum increase in mutant frequency is not observed for a range of applied concentrations that extends to toxicity causing 10% to 20% relative growth or a range of applied concentrations extending to at least twice the solubility limit in culture media.

Statistics:

No data

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

ADDITIONAL INFORMATION ON CYTOTOXICITY:
In the main study, cytotoxicity (decreased survival) was noted immediately after treatment (plating efficiency step 1) and in the following plating for 5-trifluoro-thymidine (TFT) resistance (plating efficiency step 2) in the presence and absence of metabolic activation at the top concentration of 200 ug/mL.
Cytotoxicity is defined as a reduction in the number of colonies by more than 50% compared with the negative control. Exposure to the test item at the concentration of 200 ug/mL in the absence of metabolic activation resulted in relative survival of 28% and 34% (plating efficiency step 1) and 20% and 33% (plating efficiency step 2), and in the presence of metabolic activation of 28% and 26% (plating efficiency step 1) and 23% and 17% (plating efficiency step 2). Therefore, the test item was considered cytotoxic at the top concentration of 200 ug/mL.

No relevant change in pH and osmolality was noted.

Conclusions:

Under the present test conditions, lithium hydroxide monohydrate, tested up to a pronounced cytotoxic concentration in the absence and presence of metabolic activation in two independent experiments, was negative with respect to the mutant frequency in the L5178Y TK +/- mammalian cell mutagenicity test. Under these conditions positive controls exerted potent mutagenic effects.
In addition, no change was noted in the ratio of small to large mutant colonies. Therefore, lithium hydroxide monohydrate also did not exhibit clastogenic potential at the concentration-range investigated.
According to the evaluation criteria for this assay, these findings indicate that lithium hydroxide monohydrate, tested up to a cytotoxic concentration in the absence and presence of metabolic activation did neither induce mutations nor had any chromosomal aberration potential.

Executive summary:

An in vitro mammalian cell assay was performed in mouse lymphoma L5178Y TK +/- cells to test the potential of lithium hydroxide to cause gene mutation and/or chromosome damage according to OECD Guideline 476 and the EU method B.17. Lithium hydroxide monohydrate was assayed in a gene mutation assay in cultured mammalian cells (L5178Y TK +/-) both in the presence and absence of metabolic activation by a liver post-mitochondrial fraction (S9 mix) from Aroclor 1254-induced rats. The test was carried out employing 2 exposure times without S9 mix: 3 and 24 hours, and one exposure time with S9 mix: 3 hours; this experiment with S9 mix was carried out twice. The test item was dissolved in aqua ad iniectabilia. A correction factor of 1.73 was used. The dose-levels and concentrations given in the text and tables refer to lithium hydroxide monohydrate. The limit of solubility was about 34 mg/mL. In the preliminary experiment without and with metabolic activation, concentrations tested were 0.25, 1, 2.5, 10, 25, 100 and 200 ug/mL. Cytotoxicity (decreased survival) was noted at the top concentration of 200 μg/mL. Hence, in the experiments without or with metabolic activation the concentrations of 12.5, 25, 50 100 and 200 ug/mL were used. In the main study, cytotoxicity (decreased survival) was noted immediately after treatment (plating efficiency step 1) and in the following plating for 5-trifluoro-thymidine (TFT) resistance (plating efficiency step 2) in the presence and absence of metabolic activation at the top concentration of 200 μg/mL. Methylmethanesulfonate was employed as positive control in the absence of exogenous metabolic activation and 3-Methylcholanthrene in the presence of exogenous metabolic activation. The mean values of mutation frequencies of the negative controls ranged from 61.61 to 98.34 per 106 clonable cells in the experiments without metabolic activation, and from 68.23 to 82.61 per 106 clonable cells in the experiments with metabolic activation and, hence, were well within the historical data-range. The mutation frequencies of the cultures treated with lithium hydroxide monohydrate ranged from 64.74 to 92.63 per 106 clonable cells (3 hours exposure) and 50.42 to 92.34 per 106 clonable cells (24 hours exposure) in the experiments without metabolic activation and 75.88 to 105.59 per 106 clonable cells (3 hours exposure, first assay) and 45.04 to 99.10 per 106 clonable cells (3 hours exposure, second assay) in the experiments with metabolic activation. These results were within the range of the negative control values and, hence, no mutagenicity was observed according to the criteria for assay evaluation.

Under the present test conditions, lithium hydroxide monohydrate, tested up to a pronounced cytotoxic concentration in the absence and presence of metabolic activation in two independent experiments, was negative with respect to the mutant frequency in the L5178Y TK +/- mammalian cell mutagenicity test. Under these conditions positive controls exerted potent mutagenic effects. In addition, no change was noted in the ratio of small to large mutant colonies. Therefore, lithium hydroxide monohydrate also did not exhibit clastogenic potential at the concentration-range investigated. According to the evaluation criteria for this assay, these findings indicate that Lithium hydroxide monohydrate, tested up to a cytotoxic concentration in the absence and presence of metabolic activation did neither induce mutations nor had any chromosomal aberration potential.

Reference 2

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:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

Bacteria strains were only tested in duplicate.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Additional strain / cell type characteristics:

not specified

Species / strain / cell type:

S. typhimurium TA 1538

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9 mix (rat liver induced with polychlorinated biphenyl, KC500)

Test concentrations with justification for top dose:

500, 1000, 2500, 5000, 10000, 25000 ppm

Vehicle / solvent:

- Vehicle used: sterilised air
- Justification for choice of vehicle: substance is volatile.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

2NF

Positive control substance:

2-nitrofluorene

Remarks:

without S9 mix (TA100, TA98, TA1538)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

ENNG

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

without S9 mix (TA1535, WP2 uvrA)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

9AC

Positive control substance:

9-aminoacridine

Remarks:

without S9 mix (TA1537)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

B(a)P

Positive control substance:

benzo(a)pyrene

Remarks:

with S9 mix (TA100, TA98, TA1537, TA1538)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Remarks:

2AA

Positive control substance:

other: 2-aminoanthracene

Remarks:

with S9 mix (TA1535, WP2 uvrA)

Details on test system and experimental conditions:

METHOD OF APPLICATION: via air, agar plates were placed upside down without a lid in a glass chamber

DURATION
- Exposure duration: 48 hours at 37 °C

NUMBER OF REPLICATIONS: 2

DETERMINATION OF CYTOTOXICITY
- Method: background bacterial lawn check

Rationale for test conditions:

The test substance is a gas at room temperature.

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

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:

not examined

Positive controls validity:

valid

Key result

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:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

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:

not examined

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Table 1: results

Dose (µg/plate)	Mean number of revertant colonies/2 replicate plates with different strains of Salmonella typhimurium and E.coli
	TA1535	TA1537	TA98	TA100	TA1538	WP2 uvrA
	Results with S9
Solvent control	27.8±8.4	10.3±3.8	60.7±14.1	190.6±49.3	58.3±14.2	28.8±6.1
500	31	9	63	229	37	31
1000	40	7	76	220	59	33
2500	35	9	66	181	53	31
5000	21	6	53	195	55	28
10000	34	13	60	185	52	30
25000	31	10	68	220	40	20
positive control	138.5±24.8	96.8±24.6	546.0±29.8	956.4±212.4	510.5±183.8	132.0±50.7
	Results without S9
Solvent control	31.3±7.0	11.4±3.0	48.3±7.7	191.8±39.5	31.8±8.6	32.0±5.0
500	25	11	64	243	13	36
1000	23	13	56	251	27	32
2500	29	8	43	198	23	28
5000	20	10	43	207	34	33
10000	23	7	69	197	32	33
25000	19	13	57	227	25	19
positive control	1001.4±168.5	745.0±59.1	503.2±121.9	700.0±52.8	295.6±46.5	136.8±39.8

Conclusions:

Under the present experimental conditions, ammonia did not show any genotoxic effects in the tested bacteria strains.

Executive summary:

The mutagenicity of ammonia was assessed in an Ames assay equivalent or similar to OECD guideline 471. In a reverse mutation assay in bacteria, strains (TA98, TA100, TA1535, TA1537, TA1538, WP2 uvrA) of S. typhimurium and E.coli were exposed to ammonia gas at concentrations of 500, 1000, 2500, 5000, 10000 and 25000 ppm in the presence and absence of mammalian metabolic activation.

The test chemical was tested up to a limit concentration. The prepared minimal glucose agar plate was placed upside down without a lid inside a glass chamber. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence or a concentration related positive response of induced mutant colonies over background.

Based on the above results the substance is not regarded as mutagenic in a bacterial reverse mutation assay.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Bacterial reverse mutation assay (Ames test)

The mutagenicity of ammonia was assessed in an Ames assay equivalent or similar to OECD guideline 471. In a reverse mutation assay in bacteria, strains (TA98, TA100, TA1535, TA1537, TA1538, WP2 uvrA) of S. typhimurium and E.coli were exposed to ammonia gas at concentrations of 500, 1000, 2500, 5000, 10000 and 25000 ppm in the presence and absence of mammalian metabolic activation. The test chemical was tested up to a limit concentration. The prepared minimal glucose agar plate was placed upside down without a lid inside a glass chamber. The positive controls induced the appropriate responses in the corresponding strains. There was no evidence or a concentration related positive response of induced mutant colonies over background. Based on the above results the substance is not regarded as mutagenic in a bacterial reverse mutation assay.

Mammalian cell gene mutation assay

An in vitro mammalian cell assay was performed in mouse lymphoma L5178Y TK +/- cells to test the potential of lithium hydroxide to cause gene mutation and/or chromosome damage according to OECD Guideline 476 and the EU method B.17. Lithium hydroxide monohydrate was assayed in a gene mutation assay in cultured mammalian cells (L5178Y TK +/-) both in the presence and absence of metabolic activation by a liver post-mitochondrial fraction (S9 mix) from Aroclor 1254-induced rats. The test was carried out employing 2 exposure times without S9 mix: 3 and 24 hours, and one exposure time with S9 mix: 3 hours; this experiment with S9 mix was carried out twice. In the preliminary experiment without and with metabolic activation, concentrations tested were 0.25, 1, 2.5, 10, 25, 100 and 200 ug/mL. Cytotoxicity (decreased survival) was noted at the top concentration of 200 μg/mL. Hence, in the experiments without or with metabolic activation the concentrations of 12.5, 25, 50 100 and 200 ug/mL were used. In the main study, cytotoxicity (decreased survival) was noted immediately after treatment (plating efficiency step 1) and in the following plating for 5-trifluoro-thymidine (TFT) resistance (plating efficiency step 2) in the presence and absence of metabolic activation at the top concentration of 200 μg/mL. The mean values of mutation frequencies of the negative controls ranged from 61.61 to 98.34 per 106 clonable cells in the experiments without metabolic activation, and from 68.23 to 82.61 per 106 clonable cells in the experiments with metabolic activation and, hence, were well within the historical data-range. The mutation frequencies of the cultures treated with Lithium hydroxide monohydrate ranged from 64.74 to 92.63 per 106 clonable cells (3 hours exposure) and 50.42 to 92.34 per 106 clonable cells (24 hours exposure) in the experiments without metabolic activation and 75.88 to 105.59 per 106 clonable cells (3 hours exposure, first assay) and 45.04 to 99.10 per 10^6 clonable cells (3 hours exposure, second assay) in the experiments with metabolic activation. These results were within the range of the negative control values and, hence, no mutagenicity was observed according to the criteria for assay evaluation.

Methylmethanesulfonate was employed as positive control in the absence of exogenous metabolic activation and 3-Methylcholanthrene in the presence of exogenous metabolic activation and indicated that the test conditions were adequate and that the metabolic activation system functioned properly.

Lithium hydroxide monohydrate, tested up to a pronounced cytotoxic concentration in the absence and presence of metabolic activation in two independent experiments, was negative with respect to the mutant frequency in the L5178Y TK +/- mammalian cell mutagenicity test. Therefore, lithium hydroxide monohydrate also did not exhibit clastogenic potential at the concentration-range investigated. According to the evaluation criteria for this assay, these findings indicate that lithium hydroxide monohydrate, tested up to a cytotoxic concentration in the absence and presence of metabolic activation did neither induce mutations nor had any chromosomal aberration potential.

Justification for classification or non-classification

The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. As a result the target substance is not considered to be classified and labelled as mutagenic under Regulation (EC) No 1272/2008.