Hexafluorosilicic acid

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-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

Vehicle:

no

Test organisms (species):

Daphnia magna

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

hexafluorosilicic acid

Basis for effect:

reproduction

Remarks on result:

other: based on nominal since dose verification resulted in 100% revcovery

Details on results:

- Behavioural abnormalities:
- Observations on body length and weight: no
- Other biological observations: not reported
- Mortality of control: 13.3%
- Other adverse effects control: not reported
- Abnormal responses: not reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: analytical measurements confirmed solubility
- Effect concentrations exceeding solubility of substance in test medium: no

The cumulative % mortality of the daphinds used to start the test were 13.3. 30, 20, 5, 5, 5, 25, 25 and 100 % at 0 (control), 0.32, 1, 3.2, 10, 31.6, 100, 316 and 1000 mg NaF/L, respectively. The cumulative number of live offspring produced was 89.9 87.0, 85.9, 94.7, 95.4, 99.1, 41.4, 0.0 and 0.0 juveniles/adult at 0 (control),

0.32, 1, 3.2, 10, 31.6, 100, 316 and 1000 mg NaF/L, respectively. Reproduction was affected at concentrations of 100 mg NaF/L and higher.

Applying the conversion factor from NaF to hexafluorosilicic acid, the NOEC concentration corresponds to 18.0 mg hexafluorosilicic acid/L.

Validity criteria fulfilled:

yes

Conclusions:

21-day NOEC Daphnia magna: 31.6 mg NaF/L. Applying the conversion factor from NaF to hexafluorosilicic acid, the NOEC concentration corresponds to 18.0 mg hexafluorosilicic acid/L.

Executive summary:

In the Klimisch 1 study from Kühn et al. (1989) the chronic toxicity of sodium fluoride to Daphnina magna was investigated in a 21 day semi-static test with a test design of the OECD 211. The test was performed at 25°C instead of 20°C. This is considered to have no impact on the general results of the study.

Four replicates with five daphnids (<24h) were used per concentration and control at test start. Dose verification was performed at start and end of the study. The concentrations confirmed that the test solutions were correctly dosed and stable +/- 20% of the nominal concentrations. The results were based on the nominal concentrations.

The cumulative % mortality of the daphinds used to start the test were 13.3. 30, 20, 5, 5, 5, 25, 25 and 100 % at 0 (control), 0.32, 1, 3.2, 10, 31.6, 100, 316 and 1000 mg NaF/L, respectively. The cumulative number of live offspring produced was 89.9 87.0, 85.9, 94.7, 95.4, 99.1, 41.4, 0.0 and 0.0 juveniles/adult at 0 (control),

0.32, 1, 3.2, 10, 31.6, 100, 316 and 1000 mg NaF/L, respectively. Reproduction was affected at concentrations of 100 mg NaF/L and higher. The NOEC is 31.6 mg NaF/L.

The concentration of 31.6 mg NaF/L is given as overall NOEC for this 21 day chronic daphnia study. Applying the conversion factor from NaF to hexafluorosilicic acid, the NOEC concentration corresponds to 18.0 mg hexafluorosilicic acid/L.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

see read across justification

Reason / purpose for cross-reference:

read-across source

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

32.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: overall NOEC, based on hexafluorosilicic acid

The mean measured F- concentrations were 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L. The cumulative % mortality of the daphinds used to start the test were 0, 0, 0, 15, 0 and 5 % at 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L, respectively. Hence, there was no effect of the test item on the mortality within this concentration range. The cumulative number of live offspring produced was 122.3, 130.0, 56.6, 1.7, 0, and 0 juveniles/adult at 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L, respectively. Reproduction was affected at concentrations of 35.5 mg F-/L and higher. The NOEC is 26.1 mg F-/L.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 32.9 mg hexafluorosilicic acid/L.

Validity criteria fulfilled:

yes

Conclusions:

21d-NOEC: 197 mg/L

Executive summary:

In the Klimisch 1 study from Fieser et al. (1986) the chronic toxicity of sodium fluoride to Daphnina magna was investigated in a 21 day semi-static test with a test design similar to the OECD 211. Twenty replicates with one daphnia (<24h) were used per concentration and control at test start. Dose verification was performed five times during the study. The concentrations were within +/- 20% of the nominal concentrations. The results were based on the measured concentration of the fluoride anion (F-).

The mean measured F- concentrations were 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L. The cumulative % mortality of the daphinds used to start the test were 0, 0, 0, 15, 0 and 5 % at 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L, respectively. Hence, there was no effect of the test item on the mortality within this concentration range. The cumulative number of live offspring produced was 122.3, 130.0, 56.6, 1.7, 0, and 0 juveniles/adult at 0 (control), 26.1, 35.5, 49.0, 83.8 and 141.6 mg F-/L, respectively. Reproduction was affected at concentrations of 35.5 mg F-/L and higher. The NOEC is 26.1 mg F-/L.

The mean measured concentration of 26.1 mg F-/L is given as overall NOEC for this 21 day chronic daphnia study.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration range corresponds to 32.9 mg hexafluorosilicic acid/L

Reference 3

Endpoint:

long-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

GLP compliance:

no

Duration:

90 d

Dose descriptor:

NOEC

Effect conc.:

5.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: see "Details on resluts" below

Details on results:

Experiment 1:
The amphipods survived in fluoride concentrations up to 10.28 mg F-/L, but with reduced survival at this concentration. The lack of any visible effect of fluoride on the turbellarians and the harpacticoid copepod Amphiascus parvus Sars demonstrates the suitability of Grandidierella as a sensitive test animal. Both the turbellarians and to a lesser extent Amphiascus, showed response to lack of competition for food in tanks where amphipod survival was poor.

Experiment 2
Adjustments to the dosing apparatus resulted in a mean fluoride concentration in the highest dosed tank (B6) of 9.22 mg F-/L. The results show a clearly improved population increase in fluoride concentrations slightly above background. In this experiment maximum survival was at 1.95 mg F-/L. Population response to increased fluoride concentration
returned to levels comparable to control in tanks B4 (5.51 mg F-/L)and A5 (5.59 mg F-/L). One of the tanks became diseased (B2) and its amphipod population was virtually eliminated.

Experiment 3
Anaesthetising the animals with CO2 was not entirely satisfactory; some loose eggs were still found in the muds of the tanks. The experiment was also, in terms of population performance, not as successful as the previous one, despite being run under identical conditions and starting with the same number of ovigerous females. Nevertheless the results closely matched those of the previous experiment, with best population increases recorded in tank A2, 2.14 mg F-/L and reduced populations from tank A5 onward.
Bacterial plate counts showed no evidence of the fluoride having any bacteriocidal activity.

Experiment 4
Numbers of animals in the tanks when this experiment was stopped after 90 days, were very similar to those attained in Experiment 2 and the results once again displayed markedly improved population increases in tanks receiving fluoride concentrations between 2 and 4mg F-/L. A marked drop in survival was shown by the surviving numbers at F- concentrations of between 4.68 and 6.08 mg F-/L.

The control F- concentration of the blank control (ocean water) was within about 1.34 to 1.73 mg F-/L.


In the data collection from Janssen et al. (Integrated criteria document fluorides, National Institute of Public Health and Environmental Protection Bilthoven, The Netherlands, Appendix to report no. 758474010, 1989) a NOEC of 4.1 mg F-/L is given for this 90 day study. This value will be used for the risk assessment.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration of 4.1 mg F-/L corresponds to 5.17 mg hexafluorosilicic acid/L.

Validity criteria fulfilled:

not applicable

Executive summary:

In the 90 day flow-through water sediment study from Connell and Airey (1982) the toxicity of (sodium) fluoride to two amphipods Grandidierella lutosa and G. lignorum was analysed in life-cycle experiments. In one experiment (experiment 1), the perfomance of turbellarians and the harpacticoid copepod Amphiascus parvus Sars demonstrated that Grandidierella lutosa and G. lignorum were significantly more sensitive than the other groups.

No explicit NOEC value is reported by Connell and Airey (1982). Based on the information provided, the NOEC is in the range of 3.90 to 4.48 mg F-/L.

In the data collection from Janssen et al. ( Integrated criteria document fluorides, National Institute of Public Health and Environmental Protection Bilthoven, The Netherlands, Appendix to report no. 758474010, 1989) a NOEC of 4.1 mg F-/L is given for this 90 day study. This value will be used for the risk assessment.

Applying the conversion factor from F- to hexafluorosilicic acid, the concentration of 4.1 mg F-/L corresponds to 5.17 mg hexafluorosilicic acid/L.

Description of key information

Two key freshwater long-term studies with Daphnia magna are available. The NOECs are 18 and 32.9 mg hexafluorosilic acid/L.

One marine 90 day study with marine amphipods is available which resulted in a NOEC of 5.17 mg hexafluorosilic acid/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

18 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

5.17 mg/L