Ammonium hexafluorosilicate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study completion date: 01 January 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

data owner contacted; so far the LR did not provide the full study report

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The samples of the concentration levels 3.2 to 100 mg/L and the pH control were diluted with double distilled water prior to analysis.

Vehicle:

no

Details on test solutions:

Stock solution was prepared by adding 100 mg to 1 liter of dilution water.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Pseudokirchneriella subcapitata was obtained from the Pflanzenphysiologisches Institut der Universität Göttingen Nikolausberger Weg 18, D-37073 Göttingen (Germany).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21 - 24 °C, controlled at ±2 °C during the study period

pH:

Three replicates of the highest test concentration were tested by correction of the pH-value in order to check for possible toxic effects due to the pH-value. The pH-value of these replicates were adjusted to the pH of the dilution water ± 0.2 by adding appropriate volumes of 1 M NaOH and 1 M HCl.

Nominal and measured concentrations:

Nominal: 1, 3.2, 10, 32, 100 mg/L

Details on test conditions:

Light intensity: 60 - 120 µE • m-2 • s-1; Light regime: 24 hours/day light

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 16.6 - <= 19.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were 18.0 (16.6 – 19.6) mg/L and 14.9 (10.6 – 27.8) mg/L, respectively. The NOEC-value for inhibition of specific growth rate and yield after 72 hours was 10.0 mg/L.

Results with reference substance (positive control):

ErC50= 0.74 mg/L; EyC50= 0.35 mg/L

Validity criteria fulfilled:

yes

Conclusions:

After 72 h, ErC50 for specific growth rate was 18 mg/L and EyC50 for yield was 14.9 mg/L.

Executive summary:

In this study, Sodium Fluosilicate was evaluated for its potential to cause aquatic toxicity to algae. This study was conducted according to OECD test guideline 201. The test substance was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (nominal test item concentrations): The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were 18.0 (16.6 – 19.6) mg/L and 14.9 (10.6 – 27.8) mg/L, respectively. The NOEC-value for inhibition of specific growth rate and yield after 72 hours was 10.0 mg/L.

Description of key information

The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were 18.0 (16.6 – 19.6) mg/L and 14.9 (10.6 – 27.8) mg/L, respectively. The NOEC-value for inhibition of specific growth rate and yield after 72 hours was 10.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

18 mg/L

EC10 or NOEC for freshwater algae:

10 mg/L

Additional information

Currently no study is available on Ammonium hexafluorosilicate. However a similar substance, Sodium Fluosilicate was evaluated for its potential to cause aquatic toxicity to algae. This study was conducted according to OECD test guideline 201. The test substance was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (nominal test item concentrations): The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were 18.0 (16.6 – 19.6) mg/L and 14.9 (10.6 – 27.8) mg/L, respectively. The NOEC-value for inhibition of specific growth rate and yield after 72 hours was 10.0 mg/L.