Tungsten hexafluoride

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In two laboratories, sodium fluoride was tested for induction of trifluorothymidine resistance in mouse L5178Y lymphoma cells; results were positive both with and without S9.

Link to relevant study records

Reference

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

Study period:

1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study reviewed by the United States Governmental Organisation "NATIONALTOXICOLOGY PROGRAM" (NTP), U.S. DEPARTMENT OF HEALTH AND HUMANSERVICES, PublicHealthService, National Institutes of Health.Therefore it is consired as reasonably reliable. Study done according to OECD Guideline. Read across justification is given in section 13 assessment reports: WF6 justification for read across

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Type of assay:

mammalian cell gene mutation assay

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced male Fischer 344 rat liver Sa

Test concentrations with justification for top dose:

Two laboratories performed the test. The highest dose of the study compound did not exceed 5 mg/mL.

Vehicle / solvent:

none

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Details on test system and experimental conditions:

Mouse lymphoma L5178Y cells were maintained at 37 °C as suspension cultures in Fischer's medium supplemented with 2 mM l-glutamine, 110 µg/mL sodium pyruvate, 0.05% pluronic F68, antibiotics and heat activated horse serum. To reduce the number of spontaneously occurring trifluorothymidine (TFT) resistant cells, subcultures were exposed once to medium containing THMG (thymidine, hypoxanthine, methotrexate, glycine) for one day, to THG for one day and to normal medium for 3 to 5 days.

Incubation with the study chemical continued for 4 hours, at which time the medium plus chemical was removed. The cells were resuspended in fresh medium and incubated for an additional 2 days to allow expression of the mutant phenotype. Cell density was monitored so that log phase growth was maintained. After the 48 hour expression period, 3 x 10(+6) cells were plated in medium and soft agar supplemented with trifluorothymidine for selection of TFT-resistant cells and 600 cells were plated in nonselective medium and soft agar to determine cloning efficiency. Plates were incubated at 37 °C in 5% carbon dioxide for 10 to 12 days.

Evaluation criteria:

All data was evaluated statistically for both trend and peak response. Both responses had to be significant (P<0.05) for a chemical to be considered positive and the absence of both trend and a peak response resulted in a negative call. Validation criteria are detailed in Myhr at al (1985). This assay is initially performed without S9; if a clearly positive response is not obtained, the experiment is repeated with induced S9.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Sodium fluoride was studied at two laboratories for induction of trifluorothymidine resistance in mouse L5178Y lymphoma cells. In the first laboratory, sodium fluoride was positive both with and without Aroclor 1254-induced male Fischer 344 rat liver S9, the effective doses, with and without S9, ranged from 300 to 600 µg/mL (Caspary et al, 1987). In the second laboratory, sodium fluoride was tested without S9 only, and test results were positive in the first trial at 62.5, 125, and 1,000 µg/mL and in the second trial at 800 and 900 µg/mL. The mutant colonies obtained after sodium fluoride treatment of L5178Y cells were primarily small colonies, suggesting that chromosomal abnormalities may be involved.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

The table below shows the induction of trifluorothymidine resistance in mouse L5178Y cells by sodium fluoride;
Compound	Concentration (µg/mL)	Cloning Efficiency (%)	Relative Total Growth (%)	Tft Resistant Cells	Mutant fraction
- S9		75.8 ±3.8	99.8 ±4.8	67.0 ±5.9	29.5 ±1.9
Trial 1
Distilled water
Sodium fluoride	200	85.5 ±18.5	81.5 ±8.5	80.5 ±13.5	32.0 ±2.0
	300	85.3 ±4.7	72.0 ±5.2	133.3 ±22.3	52.7 ±9.4
	400	78.7 ±0.9	41.0 ±4.0	107.7 ±4.9	45.7 ±1.9
	500	75.0 ±3.8	16.7 ±2.7	125.0 ±16.7	55.3 ±4.8
	600	79.5 ±3.5	10.0 ±1.0	196.0 ±3.0	83.0 ±5.0
	800	Lethal
Methyl methanesulfonate	5	66.7 ±2.4	70.7 ±5.2	489.0 ±43.7	244.3 ±13.2
- S9		105.7 ±9.1	100.0 ±9.1	77.0 ±2.5	24.3 ±1.9
Trial 2
Distilled water
Sodium fluoride	50	91.0 ±7.0	86.3 ±2.0	59.0 ±9.3	22.0 ±3.1
	100	92.0 ±4.0	71.5 ±8.5	75.5 ±3.5	27.0 ±0
	200	88.0 ±4.6	57.0 ±2.3	72.7 ±11.1	27.3 ±3.0
	300	89.3 ±10.2	49.3 ±3.7	58.3 ±8.7	22.0 ±2.7
	400	104.0 ±12.0	40.0 ±0.0	112.0 ±25.0	35.5 ±4.5
	500	94.3 ±7.6	17.3 ±3.0	119.0 ±28.4	41.3 ±8.5
	600	Lethal
Methyl methanesulfonate	5	66.7 ±2.4	70.7 ±5.2	489.0 ±43.7	140 ±36.5
+ S9		107.5 ±1.3	100.0 ±6.8	83.8 ±6.9	25.8 ±2.1
Trial 3
Distilled water
Sodium fluoride	100	85	75	66	26
	200	99.7 ±7.8	70.7 ±4.9	59.7 ±9.9	20.7 ±4.4
	300	94.5 ±5.5	52.0 ±9.0	110.5 ±5.5	39.5 ±4.5
	400	106.7 ±7.0	41.3 ±2.3	121 ±14.1	39.0 ±7.6
	500	72.3 ±9.2	13.3 ±3.8	177.7 ±45.1	81.0 ±19.3
	600	77.5 ±13.5	7.5 ±0.5	206.5 ±24.5	94.0 ±27.0
Methyl methanesulfonate	2.5	61.3 ±5.2	28.0 ±2.1	615.0 ±43.3	334.7 ±11.9
+ S9		82.3 ±3.0	100.0 ±9.3	81.5 ±8.7	33.0 ±2.4
Trial 3
Distilled water
Sodium fluoride	50	78.0 ±2.9	100.0 ±7.8	63.7 ±4.2	27.0 ±1.2
	100	79.3 ±6.0	86.7 ±21.1	88.7 ±14.0	37.7 ±6.8
	200	85.0 ±13.1	83.3 ±6.4	98.0 ±18.6	38.0 ±2.0
	300	76.3 ±0.3	49.7 ±3.3	119.0 ±11.8	51.7 ±5.2
	400	77.3 ±3.8	29.0 ±1.5	144.7 ±10.3	62.3 ±2.3
	500	74.3 ±3.4	21.0 ±3.1	167.7 ±27.9	75.7 ±14.3
	600	Lethal
Methyl methanesulfonate	2.5	47.7 ±2.7	21.0 ±2.7	731.7 ±22.9	573.7 ±34.6
The table below shows the results obtained for the induction of trifluorothymidine resistance in mouse L5178Y/TK cells by sodium fluoride;
Compound	Concentration (µg/mL)	Cloning Efficiency (%)	Relative Total Growth (%)	Tft Resistant Cells	Mutant fraction
- S9		58.8 ±3.0	100.0 ±10.3	101 ±14.0	58.0 ±9.7
Trial 1
Fischer’s medium without serum
Sodium fluoride	62.5	52.5 ±5.5	88.5 ±12.5	162.0 ±0.0	104.5 ±11.5
	125	52.5 ±8.5	78.0 ±4.0	144.0 ±24.0	97.5 ±31.5
	250	59.0 ±4.0	70.0 ±9.0	130.0 ±9.0	73.5 ±0.5
	500	70.0 ±15.0	36.0 ±1.0	161.5 ±18.5	82.5 ±26.5
	1000	40.0 ±4.0	8.0 ±3.0	155.5 ±13.5	134.0 ±25.0
Methyl methanesulfonate	15	16.5 ±1.5	13.0 ±2.0	172.0 ±3.0	342.5 ±24.5
- S9		90.5 ±5.72	100.0 ±5.3	138.3 ±12.8	51.0 ±4.1
Trial 2
Fischer's medium without serum
Sodium fluoride	500	82.0 ±3.0	33.0 ±0.0	145.0 ±20.0	58.5 ±5.5
	600	87.0 ±10.0	28.0 ±3.0	148.5 ±0.5	58.0 ±7.0
	700	90.5 ±3.5	25.0 ±0.0	177.0 ±25.0	66.0 ±12.0
	800	78.5 ±0.5	20.0 ±1.0	215.5 ±22.5	91.5 ±9.5
	900	78.0 ±2.0	13.0 ±1.0	445.0 ±22.0	195.5 ±3.5
	1000	Lethal
Methyl methanesulfonate	1552.0 ±4.0	52.0 ±4.0	35.0 ±1.0	77.0 ±14.0	49.0 ±5.0

Conclusions:

Interpretation of results (migrated information):
positive

In two laboratories, sodium fluoride was tested for induction of trifluorothymidine resistance in mouse L5178Y lymphoma cells; results were positive both with and without S9.

Executive summary:

Sodium fluoride was studied at two laboratories for induction of trifluorothymidine resistance in mouse L5178Y lymphoma cells. In the first laboratory, sodium fluoride was positive both with and without Aroclor 1254-induced male Fischer 344 rat liver S9, the effective doses, with and without S9, ranged from 300 to 600 µg/mL (Caspary et al, 1987). In the second laboratory, sodium fluoride was tested without S9 only, and test results were positive in the first trial at 62.5, 125, and 1,000 µg/mL and in the second trial at 800 and 900 µg/mL. The mutant colonies obtained after sodium fluoride treatment of L5178Y cells were primarily small colonies, suggesting that chromosomal abnormalities may be involved.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Additional information

Additional information from genetic toxicity in vitro:

Justification for selection of genetic toxicity endpoint
Study reviewed by the United States Governmental Organisation "NATIONALTOXICOLOGY PROGRAM" (NTP), U.S. DEPARTMENT OF HEALTH AND HUMANSERVICES, PublicHealthService, National Institutes of Health.Therefore it is consired as reasonably reliable. Study done according to OECD Guideline.