Hexafluorosilicic acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read across justification

Reason / purpose for cross-reference:

read-across source

Details on sampling:

No details on sampling given.

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

32.8 - 60.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: concentration calculated for hexafluorsilicic acid

Details on results:

Benthic larvae were very sensitive to the concentration of fluoride ion with EC50 values ranging from 26 to 48 mg F-/L (actual concentration). Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 32.8 to 60.5 mg hexafluorosilicic acid/L.

Executive summary:

Benthic larvae (Chimarra marginata,Hydropsyche lobata, Hydropsyche bulbifera, Hydropsyche exocellataandHydropsyche pellucidula) collected in Spanish rivers were found to be sensitive to the concentration of fluoride ion with EC50 values ranging from 26 to 48 mg F-/L (actual concentration). These organisms appear more sensitive than D. magna according to the EU RAR for hydrogen fluoride; however this may be a reflection of the fact that the study was performed with soft water.

Benthic larvae were very sensitive to the concentration of fluoride ion with EC50 values ranging from 26 to 48 mg F-/L (actual concentration). Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 32.8 to 60.5 mg hexafluorosilicic acid/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

supporting study

Justification for type of information:

see read across justification

Reason / purpose for cross-reference:

read-across source

Dose descriptor:

EC50

Effect conc.:

>= 137.3 - 428.4 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Remarks on result:

other: Freshwater, based on hexafluorsilicic acid

Dose descriptor:

EC50

Effect conc.:

>= 37.8 - 630 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Remarks on result:

other: Marine, based on hexafluorsilicic acid

The ICD reports EC50 values of 109 -340 mg F-/L for freshwater invertebrates and values of 30 -500 mg F-/L for marine invertebrates.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 137.3 - 428.4 and 37.8 -630 mg hexafluorosilicic acid/L for freshwater and marine invertebrates, respectively.

Executive summary:

The ICD reports EC50 values of 109 -340 mg F-/L for freshwater invertebrates and values of 30 -500 mg F-/L for marine invertebrates.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 137.3 - 428.4 and 37.8 -630 mg hexafluorosilicic acid/L for freshwater and marine invertebrates, respectively.

Description of key information

For the risk assessment the following EC50 values will be used:

Freshwater: 32.8 mg/L

Marine: 13.23 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

32.8 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

13.23 mg/L

Additional information

Benthic larvae (Chimarra marginata,Hydropsyche lobata, Hydropsyche bulbifera, Hydropsyche exocellata and Hydropsyche pellucidula) collected in Spanish rivers were found to be sensitive to the concentration of fluoride ion with EC50 values ranging from 26 to 48 mg F-/L (actual concentration). These organisms appear to be more sensitive than D. magna according to the EU RAR for hydrogen fluoride; however this may be a reflection of the fact that the study was performed with soft water.

Benthic larvae were very sensitive to the concentration of fluoride ion with EC50 values ranging from 26 to 48 mg F-/L (actual concentration). Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 32.8 to 60.5 mg hexafluorosilicic acid/L.

In the Klimisch 1 study from Fieser et al. (1986) the acute toxicity of sodium fluoride to Daphnina magna was investigated in a 48 hour static test with a test design similar to the OECD 202. Twenty daphnids (< 24 h) were exposed in 4 replicates per concentration and control at test start. Dose verification was performed at the start and end of the exposure. The results were based on the measured concentration of the fluoride anion (F-). The % immobilization of the daphinds was 0, 0, 10, 15, 80 and 100 % at nominal 0 (control), 100, 158, 251, 316 and 398 mg F-/L. The EC50 was calculated to be 247 mg F-/L. Applying the conversion factor from F- to hexafluorosilicic acid, the concentration corresponds to 311.2 mg hexafluorosilicic acid/L.

In the EU-RAR document, the listed 48h EC50 values for daphnids range from 97 to 270 mg F-/L and were based on nominal concentrations.  Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 122.2 to 340.2 mg hexafluorosilicic acid/L.

The ICD reports EC50 values of 109 -340 mg F-/L for freshwater invertebrates and values of 30 - 500 mg F-/L for marine invertebrates. Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 137.3 - 428.4 and 37.8 -630 mg hexafluorosilicic acid/L for freshwater and marine invertebrates, respectively.

Hence, benthic invertebrates were most sensitive freshwater organisms and were hence used for the risk assessment for freshwater as worst case.

For the risk assessment the following EC50 values will be used:

Freshwater: 32.8 mg/L

Marine: 13.23 mg/L