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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
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:
read-across source
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
613.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks:
above water solubility of CaF2
Remarks on result:
other: Leuciscus idus melanotus
Remarks:
Ref: Juhnke and Ludemann (1978)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
104.7 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks:
above water solubility of CaF2
Remarks on result:
other: Oncorhynchus mykiss
Remarks:
Ref: Janssen et al. (1989)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
221.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks:
above water solubility of CaF2
Remarks on result:
other: Oncorhynchus mykiss
Remarks:
Ref: Camargo and Tarazona (1991)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
338.7 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks:
above water solubility of CaF2
Remarks on result:
other: Salmo trutta
Remarks:
Ref: Camargo and Tarazona (1991)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
697.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks:
above water solubility of CaF2
Remarks on result:
other: Gasterosteus aculeatus
Remarks:
Janssen et al. (1989)

The short term LC50 endpoints provided by the soft-water studies above range from 51 to 340 mg F-/L. Using the molecular weight information, this has been recalculated to a range of 104 to 697.9 mg CaF2/L.

The EU RAR for hydrogen fluoride notes the existence of additional LC50 values in the range 128 to 460 mg F-/L, cited in the RIVM Integrated Criteria Document Fluoride (Sloof et al, 1988). Endpoints indicated for marine fish exceeded the solubility of NaF in seawater (100 mg/L) and were considered unsuitable for risk assessment.

Validity criteria fulfilled:
not specified
Conclusions:
The EU RAR for hydrogen fluoride reports short term LC50 endpoints for four species of fish, exposed in soft-water to sodium fluoride, that range from 51 to 340 mg F-/L.Using the molecular weight information, this has been recalculated to a range of 104 to 697.9 mg CaF2/L.
Executive summary:

The EU RAR reviews and summarises the results of five short-term fish toxicity studies peformed with four species of freshwater fish exposed to sodium fluoride. It is noted that all tests considered to be reliable were performed in soft water and all endpoints are expressed in terms of fluoride ion (F-) equivalents. Short term LC50 endpoints for fish exposed in soft-water to sodium fluoride range from 51 to 340 mg F-/L. Using the molecular weight information, this has been recalculated to a range of 104 to 697.9 mg CaF2/L.

Endpoint:
short-term toxicity to fish
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:
read-across source
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
Sodium fluoride is water soluble and will rapidly dissociate under the aqueous conditions of the test to form sodium and fluoride ions. The toxicity of sodium fluoride is essentially due to fluoride ions and therefore is appropriate for read-across to CaF2.
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
337.66 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 330.9 - 234
Remarks:
above water solubility of CaF2
Duration:
120 h
Dose descriptor:
LC50
Effect conc.:
278.34 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 330.9 - 234
Remarks:
above water solubility of CaF2
Duration:
144 h
Dose descriptor:
LC50
Effect conc.:
243.24 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL= 306.25-192
Remarks:
above water solubility of CaF2
Duration:
168 h
Dose descriptor:
LC50
Effect conc.:
215.73 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 276.9-167.9
Remarks:
above water solubility of CaF2
Duration:
192 h
Dose descriptor:
LC50
Effect conc.:
200.13 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 254.1-157.6
Details on results:
No fish died after exposure to sodium chloride for 192 hours. The sodium ion therefore has the lowest toxicity for aquatic organisms, this study has therefore demonstrated that the toxic effect of sodium fluoride on trout species is fundamentally due to fluoride ions. The LC50 for brown trout after exposure to sodium fluoride was 164.5, 135.6, 118.5, 105.1 and 97.5 ppm F- after 96, 120, 144, 168 and 192 h respectively.
Using the molecular weight information, this has been recalculated to LC50 values of 337.7, 278.3, 243.2, 215.7 and 200.1 ppm CaF2 after 96, 120, 144, 168 and 192 h respectively.
Results with reference substance (positive control):
Not applicable.

No further information.

Validity criteria fulfilled:
not specified
Conclusions:
The study was conducted using NaF. Since F-ions are the driver for toxicity, read-across to CaF2 is valid. Using the molecular weight information, the effect levels in ppm F- were converted to ppm CaF2: the converted LC50 values are 337.7, 278.3, 243.2, 215.7 and 200.1 ppm CaF2 after 96, 120, 144, 168 and 192 h respectively.
Executive summary:

Fish were exposed to 5 different concentrations of sodium fluoride (NaF) for 8 days. Animals were also exposed to a high concentration of sodium chloride (NaCl), i.e. 800 ppm, for 192 h. No fish died after exposure to sodium chloride (800 ppm) for 192 hours. The sodium ion therefore has the lowest toxicity for aquatic organisms, this study has therefore demonstrated that the toxic effect of sodium fluoride on trout species is fundamentally due to fluoride ions. The LC50 for brown trout after exposure to sodium fluoride was 164.5, 135.6, 118.5, 105.1 and 97.5 ppm F- after 96, 120, 144, 168 and 192 h respectively.

Using the molecular weight information, the effect levels in ppm F- were converted to ppm CaF2: the converted LC50 values are 337.7, 278.3, 243.2, 215.7 and 200.1 ppm CaF2 after 96, 120, 144, 168 and 192 h respectively.

Endpoint:
short-term toxicity to fish
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:
read-across source
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material:
Sodium fluoride is water soluble and will rapidly dissociate under the aqueous conditions of the test to form sodium and fluoride ions. The toxicity of sodium fluoride is essentially due to fluoride ions and therefore is appropriate for read-across to CaF2.
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
220.4 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 282.9-171.6
Remarks:
above water solubility of CaF2
Duration:
120 h
Dose descriptor:
LC50
Effect conc.:
189.66 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 116.0-73.6
Remarks:
above water solubility of CaF2
Duration:
144 h
Dose descriptor:
LC50
Effect conc.:
243.24 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL= 306.25 - 193.15
Remarks:
above water solubility of CaF2
Duration:
168 h
Dose descriptor:
LC50
Effect conc.:
215.73 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 276.9 - 167.9
Remarks:
above water solubility of CaF2
Duration:
192 h
Dose descriptor:
LC50
Effect conc.:
131.66 other: ppm
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL = 254.12 - 157.64
Remarks:
above water solubility of CaF2
Details on results:
No fish died after exposure to sodium chloride for 192 hours. The sodium ion therefore has the lowest toxicity for aquatic organisms, this study has therefore demonstrated that the toxic effect of sodium fluoride on trout species is fundamentally due to fluoride ions. The LC50 for rainbow trout after exposure to sodium fluoride for 96 h was 107.5 ppm. Using the molecular weight information, this has been recalculated to LC50 (96h) 220.4 ppm.
Results with reference substance (positive control):
Not applicable.
Reported statistics and error estimates:
No reported statistics or estimations.

Fry showed hypoexcitability, darkened backs and a decrease in respiration before their deaths.

Validity criteria fulfilled:
not specified
Conclusions:
The study was conducted using NaF. Since F-ions are the driver for toxicity, read-across to CaF2 is valid. Using the molecular weight information, the effect levels in ppm F- were converted to ppm CaF2: the converted LC50 values are 220.4, 189.66, 243.24, 215.73 and 64.1 ppm CaF2 at 96, 120, 144, 168 and 192 h respectively.
Executive summary:

Fish were exposed to 5 different concentrations of sodium fluoride (NaF) for 8 days. Animals were also exposed to a high concentration of sodium chloride (NaCl), i.e. 800 ppm, for 192 h. No fish died after exposure to sodium chloride (800 ppm) for 192 hours. The sodium ion therefore has the lowest toxicity for aquatic organisms, this study therefore demonstrated that the toxic effect of sodium fluoride on trout species is fundamentally due to fluoride ions.

The LC50 was 107.5, 92.4, 118.5, 105.1, 64.1 ppm F- at 96, 120, 144, 168 and 192 h respectively. Fry showed hypoexcitability, darkened backs and a decrease in respiration before their deaths.

Using the molecular weight information, the effect levels in ppm F- were converted to ppm CaF2: the converted LC50 values are 220.4, 189.66, 243.24, 215.73 and 131.66 ppm CaF2 at 96, 120, 144, 168 and 192 h respectively.

Endpoint:
short-term toxicity to fish
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:
read-across source
Principles of method if other than guideline:
The purpose of the study was to identify the effect of alkalinity, water hardness and chloride concentration on the LC50 values.
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
>= 21.3 - <= 307.9 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Remarks:
CaF2
Basis for effect:
mortality
Details on results:
There was a decrease in toxicity when hardness, alkalinity and chloride increased proportionately. Chloride appeared to be a major toxicity modifying factor to rainbow trout under soft water conditions, but not under moderately hard water conditions.
Results with reference substance (positive control):
The toxicity tests met the criteria for acceptable control performance.

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:
Toxicity of fluoride to rainbow trout was assessed. Toxicity of fluoride decreased with increasing water hardness, alkalinity and chloride concentration. The major modifying factor is chloride.
The LC50 values ranged from 10.4 to 150 mg/L F ions. Converting this to CaF2 (using the molecular weight info), the LC50 values ranged from to 21.3 to 307.9 mg/L CaF2. At medium hardness, alkalinity and chlorine content (80/20/25), the LC50 at 96 h was 111.1 mg/L F, which convert to 228.19 mg/L CaF2.
Executive summary:

In this study the toxicity of fluoride to rainbow trout was investigated together with the impact of water quality variables on the toxicity of fluoride. For this reason water hardness, chloride content and the alkalinity of the water were modified.

In the acute toxicity test (96h), the LC50 values ranges from 10.4 to 150 mg/L F ions. There was a decrease in toxicity when hardness, alkalinity and chloride increased proportionately. Overall, chloride appeared to be the major toxicity modifying factor. Results from this study demonstrate that test results on fluoride toxicity should always be considered together with the water parameters.

As fluoride is the driving element in toxicity, read-across to CaF2 can be made. Converting the LC50 values to CaF2 (using the molecular weight info), the LC50 values ranged from to 21.3 to 307.9 mg/L CaF2. At medium hardness, alkalinity and chlorine content, the LC50 was 228.19 mg/L CaF2.

Description of key information

The chosen key value was the lowest reported LC50 among all reliable evaluated studies. The reported value by Janssen et al. (1989) on Oncorhynchus mykiss, 96h exposure (EU RAR and ICD) was 51 mg F-/L, which translates to 104.7 mg CaF2/L. Note that this value is above water solubility of CaF2being 15 mg/L at 25°C.

No reliable information is available on marine water fish.

Key value for chemical safety assessment

LC50 for freshwater fish:
104.7 mg/L

Additional information

A weight of evidence approach has been used to evaluate the short-term toxicity to fish. A number of studies have been performed with the water-soluble salt, sodium fluoride 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.

LC50 values are 220.4, 189.66, 243.24, 215.73 and 131.66 ppm CaF2 at 96, 120, 144, 168 and 192 h respectively were reported for rainbow trout by Camargo & Tarazona, 1991. The same authors report LC50 value for brown trout of 337.7, 278.3, 243.2, 215.7 and 200.1 ppm CaF2 after 96, 120, 144, 168 and 192 h respectively.

The EU RAR comprehend a review of different studies concerning hydrogen fluoride toxicity. The review reports additional LC50 values of 613.7 mg/L (48h inLeuciscus idus); 221.7 mg/L in (96h inOnchorynkus mykiss) and 697.9 mg/L (96h inGasterosteus aculeatus).

Pearcy et al. 2015 also investigated the toxicity of NaF to rainbow trout, however, the purpose of the study was rather to determine the effect of water hardness, alkalinity and chloride content on the toxicity effects. The study shows a decrease in toxicity of fluoride with increasing water hardness, alkalinity and chloride content, with chloride being the major modifying factor. This study confirms that toxicity results should be considered together with information on the water quality. At medium hardness, alkalinity and chlorine content, the LC50 at 96 h was 228.19 mg/L F.