Lithium fluoride

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-04-30 to 2010-07-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

In order to confirm correct dosage and stability of exposure concentrations samples (about 50 mL) of the control and all test concentrations were taken from separate vessels including culture-medium (controls), test solutions and algae at 0 h and 72 h. In order to remove the algae from the test solutions, AES-analysis was performed after centrifugation of the samples at 3950 rpm for 10 minutes, followed by dilution of the samples in deionised water to meet the linear range of the calibration lines.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test solutions were prepared in a dilution series from a stock solution of 100 mg/L of the test item in culture-medium for the range-finding test and from a stock solution of 400 mg/L of the test item in culture-medium for the definitive test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The range-finding test and the definitive test were performed as static tests, i.e., without renewal of the test solutions. The controls were kept in culture-medium. Vessels including culture-medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. Concentration-analysis was performed at 0 h and 72 h. The algae-test was carried without adjustment of the pH.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus (Chlorophyceae, Chlorococcales),
- Strain: SAG 86.81
- Source (laboratory, culture collection): Albrecht von Haller Institut für Pflanzenwissenschaften der Universität Göttingen
- Method of cultivation: Sterile on agar tubes (0.8 % Agar). Transferred to a new agar tube every 2 months.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24.2 to 24.7 °C

pH:

in the flasks at 0 h: 7.7 to 8.0

in the flasks at 72 h: 9.6 to 10.5

The test item had a significant effect on the pH of the test solutions at the start of the exposure period.

Salinity:

NA

Nominal and measured concentrations:

Nominal test concentrations: Control, 25.0 mg/L, 50.0 mg/L, 100 mg/L, 200 mg/L, 400 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks (test volume 100 mL)
- Aeration: none
- Initial cells concentration: 5000 cells/mL
- No. of vessels per test group (replicates): 3
- No. of vessels per control group (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

80 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

112 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

The test item had no significant effect on the pH of the test solutions at the start of the exposure period. The increase of pH in the control and test concentrations of 25.0 to 400 mg/L during the exposure period is caused by the growth of the algae in the test vessels. In common with other species of freshwater algae, Desmodesmus subspicatus gains CO2 from HCO3-, leading to a release of hydroxide ions, that raise the pH of the medium. In the test the increase of pH in the control of 2.6 (> 1.5 units as recommended in OECD-Guideline 201) had no effect on the growth of the algae as the validity criteria for algal growth were fulfilled.

Reported statistics and error estimates:

The Kolmogorov-Smirnov-test determined normality of the data (α = 0.05). The results of a one-way ANOVA showed a significant effect on the specific growth rate [µ] in the presence of Lithium chloride (F = 132.8; F critical = 5, 12, α = 0.05 = 3.11). Bartlett`s test detected homogeneity of variances(α = 0.05). Dunnett`s test for comparison of the treatment groups with the control showed significant differences between the control and the effective concentrations of 50.0, 100, 200 and 400 mg/L (α = 0.05).

Concentration of the test item, cells/mL in the test flasks at 72 h, average specific growth rate [µ] over the whole testing period 0-72 h, mean value of the average specific growth rate [µ], standard deviation and coefficient of variation Vc [%], inhibition [%] and mean value of inhibition [%] of the average specific growth rate [µ] in the definitive test:

Concentration [mg/L]	Cells / mL	Average Specific growth rate [µ]	Average Specific growth rate [µ] Mean value	Standard deviation	Coefficient of variation Vc [%]	Inhibition of Average Specific growth rate [%]	Inhibition of Average Specific growth rate Mean value [%]
	72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h	0-72 h
Control 1	720000	1.66	1.66	0.01	0.90
Control 2	752000	1.67
Control 3	688000	1.64
25.0	720000	1.66	1.66	0.01	0.87	-0.01	-0.52 *
25.0	720000	1.66				-0.01
25.0	776000	1.68				-1.52
50.0	576000	1.58	1.56	0.02	1.26	4.48	5.65 **
50.0	544000	1.56				5.63
50.0	512000	1.54				6.85
100	288000	1.35	1.42	0.07	4.59	18.4	14.2 **
100	424000	1.48				10.6
100	368000	1.43				13.5
200	248000	1.30	1.28	0.03	2.64	21.4	22.6 **
200	248000	1.30				21.4
200	208000	1.24				25.0
400	144000	1.12	1.11	0.02	2.05	32.4	33.2 **
400	128000	1.08				34.8
400	144000	1.12				32.4

* Remark: A negative inhibition value means an enhancement of the parameter.

** Significant difference compared to the control according to Dunnett`s test (p = 0.05).

Validity criteria fulfilled:

yes

Conclusions:

In this 72-h algal growth inhibition test with Desmodesmus subspicatus the 72-h EC50 based on growth rate was determined as greater than 400 mg/L. The overall NOEC was determined to be 25 mg/L. The results are based on the nominal concentrations.

Executive summary:

The effect of lithium chloride on the growth of an algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201. The test solutions were prepared in a dilution series from a stock solution of 100 mg/L of the test item in culture-medium for the range-finding test and from a stock solution of 400 mg/L of the test item in culture medium for the definitive test, respectively. The stock solutions and the corresponding dilutions were prepared using a mixing device (Ultra-Turrax, Janke & Kunkel; 8000 rpm, 2 minutes). The test solutions were clear at all test concentrations. The controls were kept in culture medium. Vessels including culture-medium (controls) and test solutions were kept under the same conditions as the test vessels for concentration analysis. AES-analysis confirmed that the test solutions were correctly dosed, i.e., the recoveries were within 91.9 to 98.2 % of the nominal concentrations at study start. At the end of the exposure, i.e., after 72 hours, the recoveries ranged from 92.4 to 97.8 % of the nominal concentrations demonstrating that the lithium concentrations were stable throughout the exposure period. Consequently, the results of the definitive test were based on nominal concentrations. In this 72-h algal growth inhibition test with Desmodesmus subspicatus
- the 72-h EC50 based on growth rate was determined as greater than 400 mg lithium chloride/L,
- the overall NOEC was determined to be 25 mg lithium chloride/L.
The results are based on the nominal concentrations.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

The review includes summaries of a number of studies, performed to various guidelines

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Test type:

not specified

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

No details are reported

Test temperature:

No details are reported

pH:

No details are reported

Dissolved oxygen:

No details are reported

Salinity:

No details are reported

Nominal and measured concentrations:

No details are reported

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

123 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

other: growth inhibition

Remarks on result:

other: Selenastrum capricornutum (LeBlanc, 1984)

Executive summary:

Camargo 2003 reviews the available data on the toxicity of sodium fluoride to algae species. Expressed in terms of fluoride ion (F-), an EC50 value of 123 mg F/L was reported for the freshwater species Selenastrum capricornutum after chronic exposure of 96 hours.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

The review includes summaries of a number of studies, performed to various guidelines.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Skeletonema costatum

Test type:

not specified

Water media type:

saltwater

Total exposure duration:

96 h

Hardness:

No details are reported

Test temperature:

No details are reported

pH:

No details are reported

Dissolved oxygen:

No details are reported

Salinity:

No details are reported

Nominal and measured concentrations:

No details are reported

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

82 mg/L

Nominal / measured:

not specified

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

other: Growth inhibition

Remarks on result:

other: Skeletonema costatum (LeBlanc, 1984)

Executive summary:

Camargo 2003 reviews the available data on the toxicity of sodium fluoride to algae species. Expressed in terms of fluoride ion (F-), an 96h-EC50 value of 82 mg F/L for the seawater species, Skeletonema costatum, was reported.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

The review includes summaries of a number of studies, performed to various guidelines

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

no data

Test organisms (species):

other: various algae species

Details on test organisms:

Algae species tested: Scenedesmus sp., Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum), Ankistridesmus braunii, Cyclotella menghiniana, Oscillatoria limnetica, Scenedesmus quadricauda, Stephanodiscus minutus, Synechococcus leopoldiensis, Scenedesmus quadricauda

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

No post observation period.

Hardness:

Unknown

Test temperature:

Not stated

pH:

Not stated

Dissolved oxygen:

Not stated

Salinity:

Not stated

Nominal and measured concentrations:

nominal

Details on test conditions:

No further details on test conditions given in review.

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

43 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Scenedesmus sp. (Slooff et al. 1988)

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

122 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Pseudokirchneriella subcapitata (LeBlanc 1984)

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Ankistridesmus braunii, Cyclotella menghiniana, Oscillatoria limnetica, Scenedesmus quadricauda, Stephanodiscus minutus, Synechococcus leopoldiensis (Janssen et al. 1989)

Duration:

8 d

Dose descriptor:

NOEC

Effect conc.:

249 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Scenedesmus quadricauda (Bringmann & Kühn 1977)

Details on results:

The EC50 values for freshwater algae ranged from 43 to 122 mg/L.

Results with reference substance (positive control):

Not relevant

Reported statistics and error estimates:

Not relevant

Expressed in terms of fluoride ion (F-), EC50 values for freshwater algae range from 43 to 122 mg/L, with NOEC values of 50 -249 mg/L.

Validity criteria fulfilled:

not specified

Conclusions:

Expressed in terms of fluoride ion (F-), the EC50 values for freshwater algae ranged from 43 to 122 mg/L.

Executive summary:

The EU RAR reviews and summarizes the available data on the toxicity of sodium fluoride to freshwater algae species. The EC50 values (expressed in terms of fluoride ion, F-) for freshwater algae are reported to range from 43 to 122 mg F/L.

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

no guideline followed

Principles of method if other than guideline:

The review includes summaries of a number of studies, performed to various guidelines

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

No data

Test organisms (species):

other: various algae species

Details on test organisms:

Algae species tested: Skeletonema costatum, Amphidnium carteri, Chaetoceros gracilis, Dunaliella tertiolecta, Pvlova lutheri

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

No post observation period.

Hardness:

Unknown

Test temperature:

Not stated

pH:

Not stated

Dissolved oxygen:

Not stated

Salinity:

Not stated

Nominal and measured concentrations:

nominal

Details on test conditions:

No further details on test conditions given in review.

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

81 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Skeletonema costatum (marine alga) (LeBlanc 1984)

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 50 - <= 200 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

biomass

Remarks on result:

other: Amphidnium carteri, Chaetoceros gracilis, Dunaliella tertiolecta, Pvlova lutheri (marine algae) (Janssen et al. 1989); test duration: 14-21 d

Results with reference substance (positive control):

Not relevant

Reported statistics and error estimates:

Not relevant

Expressed in terms of fluoride ion (F-), the EC50 value for the marine algae Skeletonema costatum was 81 mg/L after an exposure duration of 96 hours. NOEC values for other marine species were reported to be in the range between 50-200 mg F/L, however the EU RAR states that these values should be used with caution due to the relatively long exposure time of 14 -21 days.

Validity criteria fulfilled:

not specified

Conclusions:

Expressed in terms of fluoride ion (F-), the EC50 value for the marine algae Skeletonema costatum was 81 mg/L after an exposure duration of 96 hours. NOEC values for other marine species were reported to be in the range between 50-200 mg/L, however the EU RAR states that these values should be used with caution due to the relatively long exposure time of 14 -21 days.

Executive summary:

The EU RAR reviews and summarizes the available data on the toxicity of sodium fluoride to aquatic algae species. Expressed in terms of fluoride ion (F-), the EC50 value for the marine algae Skeletonema costatum was 81 mg F/L after an exposure duration of 96 hours and corresponds to a value of 110.6 mg LiF/L. NOEC values for other marine species were reported to be in the range between 50-200 mg F/L (68.27 to 273.08 mg LiF/L), however the EU RAR states that these values should be used with caution due to the relatively long exposure time of 14 -21 days.

Description of key information

The EU-RAR (2001) reviews and summarizes the available data on the toxicity of sodium fluoride to freshwater and marine algae species. Expressed in terms of fluoride ion (F-), the EC50 values for freshwater algae are reported to range from 43 to 122 mg F-/L. Recalculations of these data for lithium fluoride, based on the molecular weight, resulted in a corresponding EC50 range of 58.71 to 166.58 mg LiF/L. The EC50 value for the marine algae Skeletonema costatum was 81 mg F-/L after an exposure duration of 96 hours and corresponds to a value of 110.6 mg LiF/L (EU-RAR 2001).

With regards to the long term toxicity a EC10 value of 80 mg/L was determined in a study according to OECD guideline 401 with the read-across source substance lithium chloride. Recalculations based on molecular weight result in a NOEC value of 48.95 mg/L for lithium fluoride.

Key value for chemical safety assessment

EC50 for freshwater algae:

58.71 mg/L

EC50 for marine water algae:

110.6 mg/L

EC10 or NOEC for freshwater algae:

48.95 mg/L

Additional information

A toxicity study for aquatic algae and cyanobacteria with lithium fluoride is not available. Consequently, read across was applied using study results obtained from lithium chloride and sodium fluoride.

Read-across with lithium chloride (Steinbeis-Transferzentrum 2012)

The effect of lithium chloride on the growth of an algal species Desmodesmus subspicatus over a 72 hour static exposure period was assessed according to OECD guideline 201. The algae species were exposed to 0, 25.0 mg/L, 50.0 mg/L, 100 mg/L, 200 mg/L, 400 mg/L of the test item. AES-analysis confirmed that the test solutions were correctly dosed, i.e., the recoveries were within 91.9 to 98.2 % of the nominal concentrations at study start. At the end of the exposure, i.e., after 72 hours, the recoveries ranged from 92.4 to 97.8 % of the nominal concentrations demonstrating that the lithium concentrations were stable throughout the exposure period. Consequently, the results of the definitive test were based on nominal concentrations. In this 72-h algal growth inhibition test with Desmodesmus subspicatus - the 72-h EC50 based on growth rate was determined as greater than 400 mg LiCl/L, - the overall NOEC was determined to be 25 mg LiCl/L. Based on these data, the recalculated LC50 for lithium fluoride is greater than 244.77 mg/L and the NOEC value is 15.3 mg LiF/L.

Read across with sodium fluoride (EU-RAR 2001, Camargo 2003)
The EU-RAR (2001) reviews and summarizes the available data on the toxicity of sodium fluoride to freshwater and marine algae species. Expressed in terms of fluoride ion (F-), the EC50 values for freshwater algae are reported to range from 43 to 122 mg F-/L. Recalculations of these data for lithium fluoride, based on the molecular weight, resulted in a corresponding EC50 range of 58.71 to 166.58 mg LiF/L.

The EC50 value for the marine algae Skeletonema costatum was 81 mg F-/L after an exposure duration of 96 hours and corresponds to a value of 110.6 mg LiF/L. NOEC values for other marine species were reported to be in the range between 50-200 mg F-/L (68.27 to 273.08 mg LiF/L), however the EU-RAR states that these values should be used with caution due to the relatively long exposure time of 14 -21 days.

The review paper Camargo (2003) also summarizes the toxic effects of sodium fluoride to algae species. The results are expressed in the terms of fluoride ion (F-). In this paper EC50 values of 123 mg F-/L and 82 mg F-/L after 96 hours of exposure were reported for the freshwater species Selenastrum capricornutum and the marine species Skeletonema costatum, respectively. Based on the molecular weight, the recalculated EC50 values for lithium fluoride are 167.95 mg/L for Selenastrum capricornutum and 111.96 mg/L for Skeletonema costatum.

Conclusion:

Results of the aquatic algae toxicity tests in marine and freshwater are available for different species. Based on a worst case approach the EC50 of 58.71 mg/L will be used for fresh water species and an EC50 of 110.6 mg/L for marine water species.