Lithium fluoride

Endpoint summary

Description of key information

Based on the results in several in vitro and in vivo studies, lithium fluoride is regarded as irritating to the eyes. No skin irritating properties were observed.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2015-07-08 to 2015-07-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

2013

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot No.of test material: 1812
- Expiration date of the lot/batch: May 2025

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature (15-30 °C)

Test system:

isolated skin discs

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: Adult donors

Justification for test system used:

The method with reconstructed human skin is approved by international regulatory agencies as a replacement for the identification of irritants / corrosives in the in vivo rabbit skin assay (OECD 404). The test is designed to predict and classify the skin irritant potential of chemicals according to chemical safety regulations, using the reconstructed human epidermis model EpiSkinTM Small Model (EpiSkinTMSM) and parameters related to skin irritation.

Vehicle:

physiological saline

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN
- Tissue batch number: 15-EKIN-027
- Expiry date: July 13, 2015
- Date of initiation of testing: July 8, 2015

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 20 °C
- Temperature of post-treatment incubation: 37 °C

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: once with 1x PBS solution
- Observable damage in the tissue due to washing: No
- Modifications to validated SOP: No

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 0.3 mg/mL
- Incubation time: 3 hours
- Spectrophotometer: Thermo Scientific; Multiscan FC
- Wavelength: 570 nm
- Filter: without reference filter

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- killed tissues
- Procedure used to prepare the killed tissues: Living epidermis is subjected to -20 °C (or -80 °C) for at least 48 hours; Before use killed tissue is defrozen at room temperature
- N. of replicates : 3
- Method of calculation used: The optical density is evaluated und subtracted before the % viability is calculated.

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be non-corrosive (irritant) to skin if the viability after 15 minutes exposure is greater than or equal to 50 % of the negative control.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 10 mg

NEGATIVE CONTROL
- Amount(s) applied: 10 µL

POSITIVE CONTROL
- Amount(s) applied: 10 µL
- Concentration (if solution): 5 %

Duration of treatment / exposure:

15 min

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Mean (test substance)

Value:

91

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: No
- Direct-MTT reduction: No
- Colour interference with MTT: No

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Yes
- Acceptance criteria met for positive control: Yes
- Acceptance criteria met for variability between replicate measurements: Yes

Table 1 Irritation results

		Tissue 1	Tissue 2	Tissue 3	Mean	SD
NC	Mean OD570	0.751	0.680	0.648	0.693
	Viability [% of NC]	108	98	93	100	7.65
PC	Mean OD570	0.056	0.070	0.034	0.053
	Viability [% of NC]	8	10	5	8	2.59
Test substance	Mean OD570	0.569	0.671	0.642	0.628
	Viability [% of NC]	82	97	93	91	7.6

Interpretation of results:

GHS criteria not met

Conclusions:

According to the available in vitro test, lithium fluoride is considered as non-irritant to skin.

Executive summary:

An in vitro skin irritation test was conducted according to OECD guideline 439 and EU method B.46. Disks of epidermal units (three units / chemical) were treated with the test item and incubated for 15 minutes at room temperature. Exposure of the test material was terminated by rinsing the epidermal units with 1x PBS solution. Epidermis units were then incubated at 37 °C for 42 hours in an incubator with 5 % CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in 5 % CO2 and protected from light. The resulting formazan chrystals were extracted with acidified isopropanol and quantified with the optical densities (OD) recorded spectrophotometrically. SDS 5 % aq. and 1 x PBS treated epidermis units were used as positive and negative controls, respectively. For each treated tissue, viability was expressed as a percentage relative to negative control. The test item is considered to be a skin irritant, if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less than or equal to (≤) 50 % when compared to the viability values obtained from the negative control. In this in vitro skin irritation test using the EPISKIN model, the test item lithium fluoride did not show significantly reduced cell viability in comparison to the negative control (mean relative viability: 90 %). All obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control. Therefore the test item was considered to be non-irritant to skin. Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid. The results obtained from this in vitro skin irritation test, using the EPISKIN model, indicated that the test item reveals no skin irritation potential under the utilized testing conditions. According to the current OECD Guideline No. 439, lithium fluoride is considered as non-irritant to skin and is therefore not classified.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2016-06-12

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Principles of method if other than guideline:

Corrositex TM is a quantitative in vitro corrosivity test. The model is based on the time required for the test substance to pass through a biobarrier membrane and produce a change in a chemical detection system.

GLP compliance:

yes

Test system:

artificial membrane barrier model

Details on test system:

SOURCE AND COMPOSITION OF MEMBRANE BARRIER USED
- Was the Corrositex® test kit used: Yes

WAS THE COMPATIBILITY TEST PERFORMED: Yes, test substance produced a change in colour when applied directly into the vial with CDS.

WAS THE TIMESCALE CATEGORY TEST PERFORMED: The test substance was placed into Vial A (containing an acid buffer) and Vial B (containing a base buffer), and the vials were observed for a colour change. A colour change observed in either vial is matched to a colour chart. Vial A showed a yellow color and vial B a grey colour. Based on the colour the substance was considered as category 2 substance and therefore was tested according to Category 2 test criteria.

METHOD OF DETECTION
- Indicator solution: Chemical Detection System (CDS) is composed of water and pH indicator dyes.

NUMBER OF REPLICATES: 4

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if the test substances penetrates the membrane barrier in up to 60 min.
- The test substance is considered to be non-corrosive to skin if the penetration time is below 60 min.
- Justification for the selection of the cut-off point(s): According to Corrositex packing group assignment (please also refer to "any other information on materials and methods incl. tables")

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

1

Value:

> 60

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

2

Value:

> 60

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

3

Value:

> 60

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

4

Value:

> 60

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Interpretation of results:

GHS criteria not met

Conclusions:

Lithium fluoride was not found to be corrosive in the Corrositex Assay.

Executive summary:

The potential of lithium fluoride to cause dermal corrosion was assessed by a single topical application of the test substance to the Corrositex® Biobarrier Membrane (Corrositex® assay) equivalent or similar to OECD guideline 435. The Corrositex® Biobarrier Membrane is a test system consisting of a reconstituted collagen matrix. The assay is based on the time that is required for the test substance to penetrate through the Corrositex® Biobarrier Membrane and produce a change in the Chemical Detection System (CDS). In addition to the test substance a positive and a negative control were assessed. The Corrositex® assay showed the following results: The qualification screen demonstrated that the test substance is able to react with the CDS and produce a visible color change. Therefore the membrane barrier test method was determined to be suitable for the evaluation of the corrosive potential of the test substance. A timescale category test was carried out to distinguish between weak and strong acids or bases. The test substance was assigned to timescale category 2 (having a low acid/alkaline reserve). In each test run four Corrositex® Biobarrier Membranes were treated with the test substance. The mean breakthrough time of the test substance was above 60 min. Based on the observed results it was concluded, that lithium fluoride does not show a corrosive potential in the Corrositex® -Skin Corrosion Test under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2015-07-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying Ocular Corrosives and Severe Irritants)

Version / remarks:

(2013)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU method B.48 (Isolated chicken eye test method for identifying occular corrosives and severe irritants)

Version / remarks:

(2010)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- lot/batch No.of test material: 1812
- Expiration date of the lot/batch: May 2025

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Store at room temperature (15-30 °C). Avoid contact with acids.

Species:

chicken

Details on test animals or tissues and environmental conditions:

TEST SYSTEM
- Source: TARAVIS KFT. 9600 Sárvár, Rábasömjéni út 129., Hungary

Vehicle:

unchanged (no vehicle)

Controls:

yes

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.03 g

Duration of treatment / exposure:

The gentle rinsing with 20 mL saline was performed in all test item treated eyes after the 30, 75 and 120 minutes of observation. At 180 minutes of observation one of the three eyes was totally clear, with the two other eyes gentle rising was performed again, but they were not totally cleared at 240 minutes after the post-treatment rinse.

Number of animals or in vitro replicates:

3

Details on study design:

EXPERIMENTAL PROCEDURE
Base line assessments
At the end of the acclimatization period, a zero reference measurement was recorded for cornea thickness and opacity to serve as a baseline (t=0) for each individual eye. The cornea thickness of the eyes should not change by more than ±5-7 % within approximately 45 to 60 minutes before the start of application. Changes in thickness were not observed in the eyes. Following the equilibration period, the fluorescein retention was measured. Baseline values were required to evaluate any potential test item related effects after treatment. The location of any minor findings was marked on the record sheet as a drawing, if applicable. If any eye was considered to be unsuitable following baseline assessment, it was discarded.

Test item treatment
After the zero reference measurements, one out of three eyes in the treatment group was held in a horizontal position and lithium fluoride was applied in an amount of 0.03 g by attempting to cover the cornea surface uniformly with the test substance, while taking care not to damage or touch the cornea with the application equipment. This procedure was repeated with the remaining two eyes in the treatment group.
The three positive control eyes were treated in a similar way with 0.03 g Imidazole.
One negative control eye was treated with saline solution. The saline solution was applied in a volume of 30 μL from micropipette, in such a way that the entire surface of the cornea was covered with negative control, taking care not to damage or touch the cornea with the application equipment.

Test item removal
The Imidazole and test item were stuck on the corneas surface in all eyes at 30, 75, and 120 minutes after the post-treatment rinse.
The gentle rinsing with 20 mL saline was performed in all Imidazole treated eyes after the 30, 75, 120 and 180 minutes of observation, but cornea surfaces were not totally cleared at 240 minutes after the post-treatment rinse.
The gentle rinsing with 20 mL saline was performed in all test item treated eyes after the 30, 75 and 120 minutes of observation. At 180 minutes of observation one of the three eyes was totally clear, with the two other eyes gentle rising was performed again, but they were not totally cleared at 240 minutes after the post-treatment rinse.

Measurements
The control and test item treated eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within ± 5 minutes were considered acceptable.
The cornea thickness and cornea opacity were measured at all time points. Fluorescein retention was measured on two occasions, at base line (t=0) and 30 minutes after the post-treatment rinse.

Evaluation
The endpoints evaluated were corneal opacity, swelling, fluorescein retention, and morphological effects (e.g., pitting or loosening of the epithelium).
Results from corneal opacity, swelling, and fluorescein retention were evaluated separately to generate an Isolated Chicken Eye (ICE) class for each endpoint. The ICE classes for each endpoint were then combined to generate an Irritancy Classification for each test substance.

Irritation parameter:

percent corneal swelling

Run / experiment:

up to 75 min

Value:

2

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation parameter:

percent corneal swelling

Run / experiment:

up to 240 min

Value:

3

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Value:

1

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation parameter:

fluorescein leakage

Value:

2

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

Ocular corrosion and severe irritation potential was not observed for the test substance. Based on the overall ICE Class the positive control Imidazole was classified as corrosive/severely irritating, UN GHS Classification: Category 1. Based on the overall ICE Class, the negative control NaCl (9 g/L saline) had no significant effects on the chicken eye in this study.

Table 1 lithium fluoride results and interpretation

Observation	Value		ICE Class
Mean maximum corneal swelling at up to 75 min	2 %		I
Mean maximum corneal swelling at up to 240 min	3 %		I
Mean maximum corneal opacity	1.0		II
Mean fluorescein retention	2.0		III
Other Observations		None
Overall ICE Class		1xI, 1xII, 1xIII

Table 2 Imidazole results

Observation	Value		ICE Class
Mean maximum corneal swelling at up to 75 min	29 %		IV
Mean maximum corneal swelling at up to 240 min	36 %		IV
Mean maximum corneal opacity	4.0		IV
Mean fluorescein retention	3.0		IV
Other Observations		Cornea opacity score 4 was observed in three eyes at 30 minutes after the post-treatment rinse.
Overall ICE Class		3xIV

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results of the in vitro test for eye corrosives and severe irritants in isolated chicken eyes, ocular corrosion and severe irritation potential was not observed for the test substance. On the other hand, the results were not conclusive regarding differentiation between irritation or non irritation potential.

Executive summary:

In order to evaluate the potential ocular corrosivity and irritancy of the test item lithium fluoride, an isolated chicken eye test was performed according to OECD guideline 438 and EU method B.48. The test item lithium fluoride and positive control (Imidazole) were ground before use in the study. They were applied in an amount of 0.03 g/eye by powdering the entire surface of the cornea attempting to cover the cornea surface uniformly with the test substance or positive control. Three test item treated eyes and three positive control eyes were used in this study. One negative control eye was treated with 30 μL saline solution. After an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with ~20 mL saline solution at ambient temperature and this procedure was repeated for each eye. In this ICET, lithium fluoride did not cause ocular corrosion or severe irritation in the enucleated chicken eyes. Positive and negative controls showed the expected results. The experiments were considered to be valid.

In this in vitro eye corrosives and severe irritants study, using the Isolated Chicken Eye model with lithium fluoride, no ocular corrosion or severe irritation potential was observed. According to guideline OECD 438, lithium fluoride overall in vitro classification is neither UN GHS Classification Category I (an ocular corrosive or severe eye irritant) nor No Category. Thus, test item has been categorized as “No prediction can be made”.

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1988-01-21 to 1988-03-28

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: Stable indefinitely
- Storage condition of test material: room temperature

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Animals, Inc., Denver, Pennsylvania
- Age at study initiation: Young adult
- Weight at study initiation: 3.09 kg to 3.44 kg
- Housing: individually in stainless steel cages
- Diet: ad libitum (Purina High Fiber Rabbit Chow 5326)
- Water: ad libitum (tap water)


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 21.7
- Humidity (%): 28 - 59
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 g per test eye

Duration of treatment / exposure:

The eyes of two of the rabbits remained unwashed and the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 sec after treatment.

Observation period (in vivo):

The animals were weighed once on the day before dosing. Clinical signs were recorded as noted.

Number of animals or in vitro replicates:

4 (1 male, 3 female)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The eyes of two of the rabbits remained unwashed and the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 sec after treatment. The rate of application of the wash water was approximately 100 mL/min.
- Time after start of exposure: 20 - 30 sec

SCORING SYSTEM: The eyes were scored for irritation potential at 1, 24, 48 and 72 hours and on day 4, 7, 10, 13 and 16 using the method of Draize.

TOOL USED TO ASSESS SCORE: After the 24 hour examination with a penlight type light, the eyes were examined with the aid of 2 % sodium fluorescein dye.

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.7

Max. score:

4

Reversibility:

fully reversible within: 48 hrs

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 4 days

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #3

Remarks:

washed eye

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #4

Remarks:

washed eye

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

no indication of irritation

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 13 days

Remarks on result:

positive indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

3

Max. score:

3

Reversibility:

fully reversible within: 7 days

Remarks on result:

positive indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #3

Remarks:

washed eye

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 7 days

Remarks on result:

positive indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #4

Remarks:

washed eye

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

fully reversible within: 7 days

Remarks on result:

positive indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1.3

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1.7

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #3

Remarks:

washed eye

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 72 hrs

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #4

Remarks:

washed eye

Time point:

24/48/72 h

Score:

2.3

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

positive indication of irritation

Irritant / corrosive response data:

One hour post-dosing, slight to mild corneal opacities, iritis and severe conjunctivitis were noted in all eyes. At the 48-hour scoring, mild opacities and moderate conjunctivitis were observed; one animal also had hemorrhagic conjunctivae and one had brown areas on the conjunctivae. By day 7, washed eyes had recovered, unwashed eyes had mild conjunctivitis, one of which had white, brown and hemorrhagic areas on the conjunctivae. Unwashed eyes recovered by day 16, at which time the test was terminated. Washing the eyes with tap water shortly after exposure decreased the duration of the irritation observed.

Other effects:

The mean body weight of the animals was 3.25 ± 0.145 kg on the day prior to dosing.
All animals remained healthy throughout the study.

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Under the conditions of this study, the test material is irritating to eyes.

Executive summary:

An eye irritation/corrosion study with lithium fluoride is not available. Consequently, read-across was applied using a characteristically similar compound, lithium chloride.

An acute eye irritation/corrosion study in New Zealand White rabbits was performed equivalent or similar to OECD Guideline 405. Lithium chloride anhydrous Technical was instilled into the test eyes of 4 New Zealand White rabbits at a dose of 0.1 g. The eyes of two rabbits remained unwashed while the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 seconds after treatment. Eyes were assessed for irritation using the method of Draize at 1, 24, 48 and 72 hours after installation, as well as on days 4, 7, 10, 13 and 16.

Slight to mild corneal opacities, iritis and moderate to severe conjunctivitis was noted in both washed and unwashed eyes during the study. White, brown and hemorrhagic areas were noted on the conjunctivae of two rabbits. Irritation was greatest 1 -hour after dosing, then gradually subsided. Washed eyes recovered by day 7, and unwashed eyes recovered by day 16. Washing the eyes with tap water shortly after exposure decreased the duration of the irritation observed.

The used scores of the US scheme were adapted to the EU scheme.

Reference 3

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1988-01-20 to 1988-02-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

yes

Remarks:

The study was conducted with four instead of three animals. The eyes of two of them were washed with water shortly after instillation. The treated eye of the other two animals remained unwashed.

GLP compliance:

not specified

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.: FMC-T 595

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: very hygroscopic. Kept tightly sealed.

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Hazleton Research Animals, Inc., Denver, Pennsylvania, USA
- Age at study initiation: young adults
- Weight at study initiation: 3.10 - 3.24 kg
- Housing: individually in stainless steel cages
- Diet (e.g. ad libitum): Purina High Fiber Rabbit Chow 5326, ad libitum
- Water (e.g. ad libitum): fresh tap water, ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68 - 71
- Humidity (%): 29 - 59
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

other: The left untreated eye served as a control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 g

Duration of treatment / exposure:

20-30 seconds

Observation period (in vivo):

16 days

Number of animals or in vitro replicates:

four animals (three males, one female)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing: Washing was done with fresh tap water in two out of four animals. The other two remained unwashed.
- Time after start of exposure: 20-30 seconds

SCORING SYSTEM: Draize, J.H. et al. (1944)

TOOL USED TO ASSESS SCORE: The eyes were assessed with a penlight type lamp as well as with the aid of 2 % sodium fluorescein dye.

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.66

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #3

Remarks:

eye washed

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritation parameter:

cornea opacity score

Basis:

animal #4

Remarks:

eye washed

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1.67

Max. score:

3

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #3

Remarks:

eye washed

Time point:

24/48/72 h

Score:

0.33

Max. score:

3

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #4

Remarks:

eye washed

Time point:

24/48/72 h

Score:

2.33

Max. score:

3

Reversibility:

fully reversible within: 16 days

Remarks on result:

positive indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #3

Remarks:

eye washed

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

no indication of irritation

Irritation parameter:

chemosis score

Basis:

animal #4

Remarks:

eye washed

Time point:

24/48/72 h

Score:

3.67

Max. score:

4

Reversibility:

fully reversible within: 16 days

Remarks on result:

positive indication of irritation

Irritant / corrosive response data:

One hours post-dosing, mild to severe conjunctivitis and slight corneal opacities were noted. Irritation worsened after 24 hours at which time one eye also developed a hemorrhagic conjunctivae and one eye had a white conjunctivae. After 48 hours, irritation gradually subsided and was completely resolved by study day 16. Washing the eyes with tap water shortly after exposure increased the severity of the irritation observed.

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Under the conditions of this study, the test material was considered to be irritating to both washed and unwashed eyes.

Executive summary:

An eye irritation/corrosion study with lithium fluoride is not available. Consequently, read-across was applied using a characteristically similar compound, lithium bromide.

An eye irritation study was conducted with lithium bromide anhydrous according to a non-definitive eye irritation protocol from FMC. Lithium bromide anhydrous was instilled into the test eyes of four New Zealand White rabbits at a dose of 0.10 g. The eyes of two rabbits remained unwashed while the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 seconds after treatment. Eyes were assessed for irritation using the method of Draize at 24, 48 and 72 hours after instillation.

Mild to severe conjunctivitis and slight to mild corneal opacities were noted during the study. In addition, white, brown and hemorrhagic areas were noted on the conjunctivae. All irritation resolved by study day 16, at which the test was terminated. Washing the eyes with tap water shortly after exposure increased the severity of the irritation observed. One rabbit (with washed eyes) developed significantly higher scores regarding cornea opacity (2), conjunctival redness (2.33) and chemosis (3.67) compared to the other three animals. Due to the facts it can not be totally excluded that lithium bromide is irritating.

Considering the results of this study, lithium bromide anhydrous is considered to be irritating to the eyes of New Zealand White rabbits. (FMC, 1988)

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation/corrosion

EPISKIN assay

An in vitro skin irritation test was conducted according to OECD guideline 439 and EU method B.46. Disks of epidermal units (three units / chemical) were treated with the test item and incubated for 15 minutes at room temperature. Exposure of the test material was terminated by rinsing the epidermal units with 1x PBS solution. Epidermis units were then incubated at 37 °C for 42 hours in an incubator with 5 % CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in 5 % CO2 and protected from light. SDS 5 % aq. and 1 x PBS treated epidermis units were used as positive and negative controls, respectively. For each treated tissue, viability was expressed as a percentage relative to negative control. The test item is considered to be a skin irritant, if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less than or equal to (≤) 50 % when compared to the viability values obtained from the negative control. In this in vitro skin irritation test using the EPISKIN model, the test item lithium fluoride did not show significantly reduced cell viability in comparison to the negative control (mean relative viability: 90 %). All obtained test item viability results were above 50 % when compared to the viability values obtained from the negative control. Therefore the test item was considered to be non-irritant to skin. Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid. (TOXICOOP, 2015)

 

Corrositex Assay

The potential of lithium fluoride to cause dermal corrosion was assessed by a single topical application of the test substance to the Corrositex® Biobarrier Membrane (Corrositex® assay). The Corrositex® Biobarrier Membrane is a test system consisting of a reconstituted collagen matrix. The assay is based on the time that is required for the test substance to penetrate through the Corrositex® Biobarrier Membrane and produce a change in the Chemical Detection System (CDS). In addition to the test substance a positive and a negative control were assessed. The Corrositex® assay showed the following results: The qualification screen demonstrated that the test substance is able to react with the CDS and produce a visible color change. Therefore the membrane barrier test method was determined to be suitable for the evaluation of the corrosive potential of the test substance. A timescale category test was carried out to distinguish between weak and strong acids or bases. The test substance was assigned to timescale category 2 (having a low acid/alkaline reserve). In each test run four Corrositex® Biobarrier Membranes were treated with the test substance. The mean breakthrough time of the test substance was above 60 min. Based on the observed results it was concluded, that lithium fluoride does not show a corrosive potential in the Corrositex® -Skin Corrosion Test under the test conditions chosen (FMC, 2016).

Conclusion

Considering the results of both in vitro tests, lithium fluoride is not regarded as skin irritant.

Eye irritation/corrosion

ICE assay

In order to evaluate the potential ocular corrosivity and irritancy of the test item lithium fluoride an isolated chicken eye test was performed according to OECD guideline 438 and EU method B.48. The test item lithium fluoride and positive control (Imidazole) were ground before use in the study. They were applied in an amount of 0.03 g/eye by powdering the entire surface of the cornea attempting to cover the cornea surface uniformly with the test substance or positive control. Three test item treated eyes and three positive control eyes were used in this study. One negative control eye was treated with 30 μL saline solution. After an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with ~20 mL saline solution at ambient temperature and this procedure was repeated for each eye. In this ICET, lithium fluoride did not cause ocular corrosion or severe irritation in the enucleated chicken eyes. Positive and negative controls showed the expected results. The experiments were considered to be valid.

In this in vitro eye corrosives and severe irritants study, using the Isolated Chicken Eye model with lithium fluoride, no ocular corrosion or severe irritation potential was observed. According to guideline OECD 438, lithium fluoride overall in vitro classification is neither UN GHS Classification Category I (an ocular corrosive or severe eye irritant) nor No Category. Thus, test item has been categorized as “No prediction can be made”. (TOXICOOP, 2015)

The result does not exclude an irritation potential of the test substance. For final assignment of a risk phrase at present, results from another study would be needed. Therefore read across was performed with characteristically similar substances, namely lithium bromide and lithium chloride. Two in vivo tests are available.

in vivo Eye irritation

An eye irritation study was conducted with lithium bromide anhydrous according to a non-definitive eye irritation protocol from FMC. Lithium bromide anhydrous was instilled into the test eyes of four New Zealand White rabbits at a dose of 0.10 g. The eyes of two rabbits remained unwashed while the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 seconds after treatment. Eyes were assessed for irritation using the method of Draize at 24, 48 and 72 hours after instillation.

Mild to severe conjunctivitis and slight to mild corneal opacities were noted during the study. In addition, white, brown and hemorrhagic areas were noted on the conjunctivae. All irritation resolved by study day 16, at which the test was terminated. Washing the eyes with tap water shortly after exposure increased the severity of the irritation observed. One rabbit (with washed eyes) developed significantly higher scores regarding cornea opacity (2), conjunctival redness (2.33) and chemosis (3.67) compared to the other three animals. Due to this fact, it cannot be completely excluded that lithium bromide is irritating, therefore lithium bromide anhydrous is considered to be irritating to the eyes of New Zealand White rabbits. (FMC, 1988)

An acute eye irritation/corrosion study in New Zealand White rabbits was performed with lithium chloride in accordance with OECD Guideline 405: Lithium Chloride Anhydrous Technical was instilled into the test eyes of 4 New Zealand White rabbits at a dose of 0.1 g. The eyes of two rabbits remained unwashed while the eyes of the remaining two rabbits were gently washed with 100 mL of tap water approximately 20 - 30 seconds after treatment. Eyes were assessed for irritation using the method of Draize at 1, 24, 48 and 72 hours after installation, as well as on days 4, 7, 10, 13 and 16.

Slight to mild corneal opacities, iritis and moderate to severe conjunctivitis was noted in both washed and unwashed eyes during the study. White, brown and hemorrhagic areas were noted on the conjunctivae of two rabbits. Irritation was greatest 1 -hour after dosing, then gradually subsided. Washed eyes recovered by day 7, and unwashed eyes recovered by day 16. Washing the eyes with tap water shortly after exposure decreased the duration of the irritation observed.

Conclusion

On the basis of the results in the above studies eye irritation cannot be totally excluded for lithium fluoride neither in vitro nor in vivo. Lithium fluoride is therefore classified accordingly.

Justification for classification or non-classification

Based on the above results, lithium fluoride needs to be classified and labelled as eye irrit. cat. 2, H319 (Causes serious eye irritation) according to Regulation (EC) No 1272/2008.