Hydrogen fluoride

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

8 days

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Non-GLP, published data.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: U.S Environmental Protection Agency, 600/3-75-009: Method for Acute Toxicity Tests with Fish and Macroinvertebrates

GLP compliance:

no

Specific details on test material used for the study:

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 HF.

Analytical monitoring:

yes

Details on sampling:

No details on sampling given.

Vehicle:

no

Details on test solutions:

Test fluoride solutions were prepared from sodium fluoride, geometrically increasing the concentration with an approximate factor of 1.6. A control and five different fluoride concentrations were used per bioassay. Fluoride bioassays were performed in duplicate. Fluoride concentrations were monitored daily using an Orion model 94-09 specific ion electrode.

Test organisms (species):

Salmo trutta

Details on test organisms:

Test organisms were acclimatized to water quality conditions for 4 days prior to fluoride bioassays and were not fed during the acclimatization and toxicity bioassay. No fish died during the acclimatisation. Dead fish were removed daily during fluoride toxicity bioassays.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

192 h

Post exposure observation period:

No post exposure period

Hardness:

21.2 ±2.55 ppm

Test temperature:

16.1 ±0.13 °C

pH:

7.63 ±0.179

Dissolved oxygen:

10.1 ±0.20

Salinity:

Not reported

Nominal and measured concentrations:

Measured

Details on test conditions:

Laboratory bioassays were performed in a glass aquaria each containing 20 L of dechlorinated tap water. Necessary water oxygenation and turbulence were produced by an air pump per aquarium. Natural photoperiod was utilised and water temperature was maintained by means of a cooling unit wih thermostat. A control and five different fluoride concentration aquaria were used per bioassay. Fluoride bioassays were performed in duplicate. Each trout species was separately tested using ten fish per aquarium.

A variety of water parameters are given above. Further parameters tested were:
- Alkalinity: 32.2 ± 1.92 ppm
- Chloride: 10.8 ±0.43 ppm

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

164.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 161.2-114.0

Duration:

120 h

Dose descriptor:

LC50

Effect conc.:

135.6 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 161.2-114.0

Duration:

144 h

Dose descriptor:

LC50

Effect conc.:

118.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL= 149.2-94.1

Duration:

168 h

Dose descriptor:

LC50

Effect conc.:

105.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 134.9-81.8

Duration:

192 h

Dose descriptor:

LC50

Effect conc.:

97.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 123.8-76.8

Details on results:

No fish died after exposure to sodium chloride for 196 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 after 96, 120, 144, 168 and 192 h respectively.

Results with reference substance (positive control):

Not applicable.

Sublethal observations / clinical signs:

No further information.

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 was 164.5, 135.6, 118.5, 105.1 and 97.5 ppm F- after 96, 120, 144, 168 and 192 h respectively.

Executive summary:

No fish died after exposure to sodium chloride (1000 ppm) for 196 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.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

8 days

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Non-GLP, published data

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: U.S Environmental Protection Agency, 600/3-75-009: Method for Acute Toxicity Tests with Fish and Macroinvertebrates

GLP compliance:

no

Specific details on test material used for the study:

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 HF.

Analytical monitoring:

yes

Details on sampling:

No details on sampling given.

Vehicle:

no

Details on test solutions:

Test fluoride solutions were prepared from sodium fluoride, geometrically increasing the concentration with an approximate factor of 1.6. A control and five different fluoride concentrations were used per bioassay. Fluoride bioassays were performed in duplicate. Fluoride concentrations were monitored daily using an Orion model 94-09 specific ion electrode.

To find out whether the toxicity of sodium fluoride was due to fluoride ions, sodium and conductivity toxicity tests were conducted parallel to fluoride toxicity bioassays using sodium chloride.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

Test organisms were acclimatized to water qulaity conditions for 4 days prior to fluoride bioassays and were not fed during the acclimatization and toxicity bioassay. No fish died during the acclimatisation. Dead fish were removed daily during fluoride toxicity bioassays.

The test organisms were fry of Salmo gairdneri (rainbow trout) and Salmo trutta (brown trout) and were obtained from a Spanish ICONA trout hatchery. The fry used in the experiment were about two months old and after fluoride toxicity bioassays weighed (dry weight) 118.9 ±14.9 mg for S. gairdneri.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

192 h

Post exposure observation period:

No post exposure period

Hardness:

22.4 ±1.79 ppm for the Salmo gairdneri

Test temperature:

15.3 ±0.22 °C

pH:

7.58 ±0.179

Dissolved oxygen:

10.1 ±1.22

Salinity:

not reported

Nominal and measured concentrations:

Measured.

Details on test conditions:

Laboratory bioassays were performed in a glass aquaria each containing 20 L of dechlorinated tap water. Necessary water oxygenation and turbulence were produced by an air pump per aquarium. Natural photoperiod was utilised and water temperature was maintained by means of a cooling unit wih thermostat. A control and five different fluoride concentration aquaria were used per bioassay. Fluoride bioassays were performed in duplicate. Each trout species was separately tested using ten fish per aquarium.

A variety of water parameters are given above. Further parameters tested were:
- Alkalinity: 37.5 ±2.09 ppm
- Chloride: 10.0 ±1.22 ppm

Reference substance (positive control):

yes

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

107.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 138.0-83.7

Duration:

120 h

Dose descriptor:

LC50

Effect conc.:

92.4 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: % CL = 116.0-73.6

Duration:

144 h

Dose descriptor:

LC50

Effect conc.:

118.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL= 149.2-94.1

Duration:

168 h

Dose descriptor:

LC50

Effect conc.:

105.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 134.9-81.8

Duration:

192 h

Dose descriptor:

LC50

Effect conc.:

64.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 123.8-76.8

Details on results:

No fish died after exposure to sodium chloride for 196 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.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

No reported statistics or estimations.

Sublethal observations / clinical signs:

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

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 was 107.5, 92.4, 118.5, 105.1, 64.1 ppm F- at 96, 120, 144, 168 and 192 h respectively.

Executive summary:

No fish died after exposure to sodium chloride (800 ppm) for 196 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.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

other: review

Adequacy of study:

weight of evidence

Study period:

48 to 96 hours

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

The EU RAR contains a review and summary of available data. Methodologcial data for individual studies are incomplete, however the studies have been assessed as part of the EU RAR and are therefore considered to be suitably reliable.

Qualifier:

no guideline followed

Principles of method if other than guideline:

A number of non-guideline studies are reviewed and summarised.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

other: summary of finidngs in various species

Water media type:

freshwater

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

299 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Leuciscus idus melanotus

Remarks:

(Juhnke and Ludemann, 1978)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

51 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Oncorhynchus mykiss

Remarks:

(Janssen et al., 1989)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

108 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Oncorhynchus mykiss

Remarks:

(Camargo and Tarazona, 1991)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

165 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Salmo trutta

Remarks:

(Camargo and Tarazona, 1991)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

340 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Gasterosteus aculeatus

Remarks:

(Janssen et al., 1989)

Sublethal observations / clinical signs:

The short term LC50 endpoints provided by the soft-water studies above range from 51 to 340 mg F-/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.

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.

Reference 4

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:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF).

In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H+) and fluoride (F−) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na+) and F- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F- ions in the aquatic environment, with any effects observed being directly attributable to the F- ion. The Na+ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

Reason / purpose for cross-reference:

read-across source

Water media type:

freshwater

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

299 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Leuciscus idus melanotus

Remarks:

(Juhnke and Ludemann, 1978)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

51 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Oncorhynchus mykiss

Remarks:

(Janssen et al., 1989)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

108 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Oncorhynchus mykiss

Remarks:

(Camargo and Tarazona, 1991)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

165 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Salmo trutta

Remarks:

(Camargo and Tarazona, 1991)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

340 mg/L

Nominal / measured:

nominal

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: Gasterosteus aculeatus

Remarks:

(Janssen et al., 1989)

Sublethal observations / clinical signs:

The short term LC50 endpoints provided by the soft-water studies above range from 51 to 340 mg F-/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.

Executive summary:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF). In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H⁺) and fluoride (F⁻) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na⁺) and F^-ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F^- ions in the aquatic environment, with any effects observed being directly attributable to the F^- ion. The Na⁺ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

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.

Reference 5

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:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF).

In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H+) and fluoride (F−) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na+) and F- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F- ions in the aquatic environment, with any effects observed being directly attributable to the F- ion. The Na+ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

Reason / purpose for cross-reference:

read-across source

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

107.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 138.0-83.7

Duration:

120 h

Dose descriptor:

LC50

Effect conc.:

92.4 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: % CL = 116.0-73.6

Duration:

144 h

Dose descriptor:

LC50

Effect conc.:

118.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL= 149.2-94.1

Duration:

168 h

Dose descriptor:

LC50

Effect conc.:

105.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 134.9-81.8

Duration:

192 h

Dose descriptor:

LC50

Effect conc.:

64.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 123.8-76.8

Details on results:

No fish died after exposure to sodium chloride for 196 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.

Results with reference substance (positive control):

Not applicable.

Reported statistics and error estimates:

No reported statistics or estimations.

Sublethal observations / clinical signs:

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

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 was 107.5, 92.4, 118.5, 105.1, 64.1 ppm F- at 96, 120, 144, 168 and 192 h respectively.

Executive summary:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF). In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H⁺) and fluoride (F⁻) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na⁺) and F^- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F^- ions in the aquatic environment, with any effects observed being directly attributable to the F^- ion. The Na⁺ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

No fish died after exposure to sodium chloride (800 ppm) for 196 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.

Reference 6

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:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF).

In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H+) and fluoride (F−) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na+) and F- ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F- ions in the aquatic environment, with any effects observed being directly attributable to the F- ion. The Na+ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

Reason / purpose for cross-reference:

read-across source

Limit test:

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

164.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 161.2-114.0

Duration:

120 h

Dose descriptor:

LC50

Effect conc.:

135.6 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 161.2-114.0

Duration:

144 h

Dose descriptor:

LC50

Effect conc.:

118.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL= 149.2-94.1

Duration:

168 h

Dose descriptor:

LC50

Effect conc.:

105.1 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 134.9-81.8

Duration:

192 h

Dose descriptor:

LC50

Effect conc.:

97.5 other: ppm

Conc. based on:

other: fluoride ion (F-)

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL = 123.8-76.8

Details on results:

No fish died after exposure to sodium chloride for 196 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 after 96, 120, 144, 168 and 192 h respectively.

Results with reference substance (positive control):

Not applicable.

Sublethal observations / clinical signs:

No further information.

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 was 164.5, 135.6, 118.5, 105.1 and 97.5 ppm F- after 96, 120, 144, 168 and 192 h respectively.

Executive summary:

It is considered appropriate to address the short-term toxicity to fish data requirement for hydrogen fluoride (HF) by read-across to available data on sodium fluoride (NaF). In water, HF (as hydrofluoric acid when in water) dissociates rapidly to form hydrogen (H⁺) and fluoride (F⁻) ions, whereas NaF (the highly soluble sodium salt of fluoride) will be fully hydrated in water as separate sodium (Na⁺) and F^-ions. Both HF and NaF (as well as other fluorides) will therefore dissociate rapidly to form F^- ions in the aquatic environment, with any effects observed being directly attributable to the F^- ion. The Na⁺ ion is naturally occurring and regulated by organisms (i.e. by homeostatic mechanisms) and consequently is not considered to have an impact on the read-across of ecotoxicological data. On this basis, the profile of HF is comparable to that of NaF with respect to the environment.

No fish died after exposure to sodium chloride (1000 ppm) for 196 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.

Description of key information

A number of non-standard studies are available for sodium fluoride; short-term LC50 values range from 51-340 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

51 mg/L

Additional information

LC50 values of 107.5, 92.4, 118.5, 105.1, 64.1 ppm at 96, 120, 144, 168 and 192 h respectively are reported for rainbow trout (Camargo & Tarazona, 1991). The same authors report LC50 value for brown trout of 164.5, 135.6, 118.5, 105.1 and 97.5 ppm after 96, 120, 144, 168 and 192 h respectively. The EU RAR for hydrogen fluoride reports additional LC50 values of 299 mg/L (48 h in Leuciscus idus); 51 mg/L in (96 h in Onchorynchus mykiss) and 340 mg/L (96 h in Gasterosteus aculeatus). The RIVM Integrated Criteria Document reports additional data, with LC50 values ranging from 128-460 mg/L (Sloof et al, 1988). The RIVM document also reports LC50 values of >100 mg/L (the limit of solubility) for sodium fluoride in seawater.

The key value for the risk assessment is considered to be an LC50 of 51 mg/L in Onchoryhnchus mykiss reported by Janssen (1989).