Ammonium hexafluorosilicate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study completion date - 01 January 2010.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Sodium hexafluorosilicate

Analytical monitoring:

yes

Details on sampling:

The samples of the concentration levels 6.25 to 100 mg/L and the pH control were diluted with double distilled water prior to analysis.

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

20 daphnids, divided into 4 replicates, each with 5 daphnids per concentration level, pH-control and control. 2 to 24 h old daphnids were used for the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

244 mg CaCO3/L

Test temperature:

18 - 22 °C, ± 1 °C constant

pH:

pH=8. The highest test concentration of 100 mg/L was adjusted to a pH in the range 7.0 ± 0.2 by addition of 1 M NaOH and tested under the same conditions as the test and control groups. Additionally, a pH-control was included in the test series, because the highest test concentration showed a pH-value of 3.55, which is outside the recommended range of pH 6 to 9.

Dissolved oxygen:

The dissolved O2 concentration was >3 mg/L: 8.30 mg/L

Salinity:

0.1%

Nominal and measured concentrations:

Nominal concentrations: 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L, prepared with dilution water.

Details on test conditions:

Illumination: Diffuse light, illumination strength max. 20 µE.m-2.s-1; Photoperiod: 16/8 h light/dark cycle; Feeding: The daphnids were not fed during the study.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 35.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

ca. 50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Daphnids were exposed to disodium hexafluorosilicate in water solutions of concentrations of 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L. EC100-values after 24 and 48 h, the NOEC and LOEC after 48 h were deduced directly from the observation data without mathematical calculation.

Table: Observations of mobility

Nominal concentration of the Test Item	IMMOBILIZATION [%]
	24 h					48 h
	Replicates					Replicates
[mg/L]	1.	2.	3.	4.	MV	1.	2.	3.	4.	MV
100 (pH control)*	0	0	0	0	0	0	0	0	0	0
100	100	100	100	100	100	100	100	100	100	100
50.0	100	100	100	100	100	100	100	100	100	100
25.0	0	0	0	0	0	0	0	0	0	0
12.5	0	0	0	0	0	0	0	0	0	0
6.25	0	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

EC50=35.4 mg/l; NOEC= 25 mg/l; LOEC= 50 mg/l.

Executive summary:

Sodium hexafluorosilicate was evaluated for short term toxicity to aquatic invertebrates in a study conducted according to OECD Guideline 202. 2 to 24 h old daphnids were used for the study. 20 daphnids, divided into 4 replicates, each with 5 daphnids per concentration level, were exposed to nominal concentrations of 6.25, 12.5, 25.0, 50.0 and 100 mg/L for 48 hours only. While, no immobility was recorded at the concentrations of 6.25, 12.5 and 25.0 mg/l, 100 % immobility was recorded at 50 and 100 mg/l concentrations.

 

Based on these findings, sodium hexafluorosilicate was estimated to have 48 hour EC50 of 35.4 mg/l, while NOEC and LOEC were 25 and 50 mg/l, respectively.

Description of key information

48 h EC50 was determined to be 35.4 mg/l and NOEC and NOEL were calculated to be 25 mg/l and 50 mg/l respectively.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

35.4 mg/L

Additional information

An 48 h acute toxicity test using Daphnia magna was performed following OECD Guideline 202 in accordance to GLP. 2 to 24 h old 20 daphnids, divided into 4 replicates, each with 5 daphnids per concentration level, pH-control and control. Daphnids were exposed to disodium hexafluorosilicate in water solutions of concentrations of 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L.EC100-values after 24 and 48 h, the NOEC and LOEC after 48 h were deduced directly from the observation data without mathematical calculation. 48 h EC50 was determined to be 35.4 mg/l and NOEC and NOEL were calculated to be 25 mg/l am 50 mg/l, respectively.