Calcium 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:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

A read-across justification is provided in section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

560.73 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

CaF2

Basis for effect:

growth rate

Remarks:

cell growth

Details on results:

The alga was relatively unsensitive to fluoride.

Analytical results fluoride:

Measurement of fluoride were in good agreement with target concentrations: (101 +/- 9%) of target. Fluoride levels measured at test termination were 96 +/- 10% of the concentration at test start.

Validity criteria fulfilled:

yes

Conclusions:

The alga is relatively unsensitive to fluoride, with an IC50 (cell growth) of 273 mg/L F. This translates to 560.73 mg/L CaF2.

Executive summary:

A 72 -h study was conducted on Pseudokirchneriella subcapitata to assess the toxicity of fluoride in the presence of chloride and in hard water. The alga was found to be relatively insensitive to fluoride with an IC50 value (cell growth) 273 mg/L F. This translates to 560.73 mg/L CaF2.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

A read-across justification is provided in section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 390 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 390 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

ErC50: 0.83 mg/L

Growth rate and growth inhibition:

Measured concentration		growth rate	inhibition rate
(mg/L)		(0-3 d)	(%)
control	A	1.6	-
	B	1.5	-
	C	1.5	-
	D	1.5	-
	E	1.5	-
	F	1.5	-
	Mean	1.5	-
	std dev	0.015	-
100	A	1.5	2.5
	B	1.5	2.6
	C	1.5	2.8
	D	1.5	-0.82
	E	1.5	-2.1
	F	1.5	0.72
	Mean	1.5	0.7
	std dev	0.033	2.2

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 and NOEC value (growth rate) is determined to be > 100 mg HF/L. Using the molecular weight, this results in a EC50 and NOEC value of ≥ 390 mg/L CaF2.

Executive summary:

The Ministry of Environment in Japan conducted a study to assess toxicity to algae according to OECD 201. After 72h exposure, the EC50 and NOEC are determined to be ≥ 100 mg HF/L and the NOEC, based on growth rate. Using the molecular weight, this results in a EC50 and NOEC value of ≥ 390 mg/L CaF2.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Recently published review.

Justification for type of information:

A read-across justification is provided in section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

88.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Scenedesmus sp.

Remarks:

above water solubility of CaF2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

250.58 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Selenastrum capricornutum

Remarks:

above water solubility of CaF2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

166.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Skeletonema costatum

Remarks:

above water solubility of CaF2

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

102.7 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Ankistridesmus braunii, Cyclotella menghiniana, Oscillatoria limnetica, Scenedesmus quadricauda, Stephanodiscus minutus, Synechococcus leopoldiensis

Remarks:

above water solubility of CaF2

Duration:

8 d

Dose descriptor:

NOEC

Effect conc.:

511.43 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Scenedesmus quadricauda

Remarks:

above water solubility of CaF2

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 102.7 - <= 410.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Amphidnium carteri, Chaetoceros gracilis, Dunaliella tertiolecta, Pvlova lutheri

Remarks:

above water solubility of CaF2

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 102.7 - <= 410.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Amphidnium carteri, Chaetoceros gracilis, Dunaliella tertiolecta, Pvlova lutheri

Remarks:

above water solubility of CaF2

Details on results:

The EC50 values for freshwater algae ranged from 43 to 122 mg F-/L. For marine algae the EC50 was 81 mg F-/L for Skeletonema costatum. Using the molecular weight information, this corresponds to EC50 values ranging from 88.3 to 250.58 mg CaF2/L for freshwater algae. For marine algae the EC50 value is 166 mg CaF2/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 F-/L, with NOEC values of 50 -249 mg F-/L. For marine algae the EC50 was 81 mg/L for Skeletonema costatum; NOEC values of 50 -200 mg F-/L are reported 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 values for freshwater algae ranged from 43 to 122 mg F-/L. For marine algae the EC50 was 81 mg F-/L for Skeletonema costatum. Using the molecular weight information, this corresponds to EC50 values ranging from 88.3 to 250.58 mg CaF2/L for freshwater algae. For marine algae the EC50 value is 166 mg CaF2/L.

Executive summary:

The EU RAR reviews and summarises the available data on the toxicity of sodium fluoride to freshwater and marine 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. Using the molecular weight information, this corresponds to EC50 values ranging from 88.3 to 250.4 mg CaF2/L for freshwater algae.

For marine algae the EC50 was 81 mg F-/L in a single study with Skeletonema costatum. This corresponds to EC 50 value of 166 mg CaF2/L.

NOEC vlaues of 50 -249 mg F-/L and 50 -200 mg F-/L are reported for freshwater and marine algae, respectively. This corresponds to 102.7 - 511.43 mg CaF2/L for freshwater algae and 102.7 - 410.8 mg CaF2/L for marine algae.

Description of key information

No studies are available for calcium fluoride. Available studies on fluoride were used as read-across source.

The chosen key values were the lowest reported as EC50 for short term studies (up to 96 h) and NOECs for long term studies (up to 21 days). The values were drawn for the EU RAR 2001 review, which summaries different studies on a wide range of marine and freshwater algae.

The lowest EC50 value among the freshwater algae was 43 mg/L F- for Scenedesmus sp, which converts to 88.32 mg/L CaF2.

The lowest EC50 value among the marine algae was 81 mg/L F- for Skeletonema costatum, which converts to 166.37 mg/L CaF2.

The lowest NOEC value among the freshwater and marine algae was 50 mg/L F-, which converts to 102.7 mg/L CaF2.

Key value for chemical safety assessment

EC50 for freshwater algae:

88.32 mg/L

EC50 for marine water algae:

166.37 mg/L

EC10 or NOEC for marine water algae:

102.7 mg/L

Additional information

A weight of evidence approach has been used to evaluate the toxicity to algae. A number of studies have been performed with the water-soluble salt and so toxicity of CaF2 was assessed using a read-across method for analogue substance. Effective concentrations were recalculated taking in account the different molecular weight of the source and target substance.

Additionally, two reliable studies were conducted on Pseudokirchneriella subcapitata.

The Japanese environmental agency exposed the algae to NaF yielding results in the same order of magniture of the EU RAR 2001 review. EC50 72 h for growth rate an biomass was > 390 mg/L CaF2. Pearcy et al. (2015) confirmed that the alga is relatively insensitive to fluoride, with an IC50 value of 560 mg/L CaF2.