Ammonium hexafluorosilicate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011/06/08 - 2012/02/21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2006/3/26

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

Ammonium hexafluorosilicate

EC Number:

240-968-3

EC Name:

Ammonium hexafluorosilicate

Cas Number:

16919-19-0

Molecular formula:

F6Si.2H4N

IUPAC Name:

diammonium hexafluorosilicate

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Ammoniumhexafiuorosilicate; Batch No.: GRA 2011-007; purity: 98.9 %.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from the freshly prepared test media (containing algae) of all test concentrations and from the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period).

Test solutions

Vehicle:

yes

Details on test solutions:

Reconstituted Water (OECD Medium): Analytical grade salts were added at the following nominal concentrations in deionised water (conductivity < 5 µScm^-1):
NaHC03 50.0 mg/l
CaCl2 x 2 H2O 18.0 mg/l
NH4CI 15.0 mg/l
MgSO4 X 7 H2O 15.0 mg/l
MgCl2 X 6 H2O 12.0 mg/l
KH2PO4 1.6 mg/l
Na2EDTA x 2 H2O 100.0 µg/l
FeCl3 x 6 H2O 64.0 µg/l
MnCl2 x 4 H2O 415.0 µg/l
H3BO3 185.0 µg/l
Na2MoO4 x 2 H2O 7.0 µg/l
ZnCl2 3.0 µg/l
CoCl2 x 6 H2O 1.5 µg/l
CUC12 x 2 H2O 0.01 µg/l

Test organisms

Test organisms (species):

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

Details on test organisms:

Pseudokirchneriella subcapitata, Strain No. 61.81 SAG
cultivated in the laboratories of IBACON; original source: "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen", 37073 Göttingen, Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

none

Test conditions

Test temperature:

23 °C

pH:

8.1 (start)
8.5-8.9 (end)

Nominal and measured concentrations:

0, 1, 3.2, 10, 32, 100 mg/l

Details on test conditions:

Erlenmeyer flasks of 50 mL volume with 50 mL of test medium.
Continuous illumination
The light intensity was measured once during the test at 6 positions distributed over the experimental area at the surface of the test media.
Mean light intensity: 6362 lux (range: 6110 to 6730 lux)
Test conditions were recorded with suitable instruments and documented in the raw data.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Key result

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

Effect concentrations 5

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 6

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 7

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 75.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 8

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 22.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 9

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 10

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Reported statistics and error estimates:

none

Any other information on results incl. tables

The quantification of the ammonium of the test item was performed using ion chromatography with conductivity detection (IC-CD). At the start of the test 119 % of the nominal test concentration was found (mean value from test concentrations of nominal 10 to 100 mg/L). In the aged test media a recalculation from the ammonium concentration to the corresponding concentration of test item was not performed, since the results were not reasonable. Perhaps the high algae density in the aged test media influences the ammonium concentration or its determination.

Since correct dosing was demonstrated, all reported results refer to nominal concentrations.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The influence of Ammoniumhexafluorosilicate on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static dose-response test. The 72-hour ErC50 value was calculated to be > 100 mg test item/L and the 72-hour EyC50 was calculated to be > 100 mg test item/L. The 72-hour NOErC was determined to be 10 mg test item/L and the associated 72-hour LOErC is 32 mg test item/L. The 72-hour NOEyC was determined to be 3.2 mg test item/L and the associated 72-hour LOEyC is 10 mg test item/L.

Executive summary:

The purpose of this test was to determine the inhibitory effect of the test item Ammoniumhexafiuorosilicate on the growth of the freshwater green algae Pseudokirchneriella subcapitata. Exponentially growing cultures of this unicellular green algal species were exposed to various concentrations of the test item under defined conditions. The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations.