Dihydrogen hexafluorotitanate(2-)

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:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

adopted 2004-04-13

Deviations:

no

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Samples of all test solutions were taken for chemical analysis. Samples were taken from all respective test solutions at test start (fresh) and after 48 h exposure (aged). The test solutions were analysed for fluoride and titanium. Samples of fresh and aged test media of all treatments and the control were analysed using an ISE probe for fluoride and ICP-MS for titanium.
Results can be found in the field "Any other information on results incl. tables" below.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
A solution was prepared by dissolving 5000 mg of the test item in 5000 mL of copper-reduced dilution water and stirring for 2 h at 300 rpm. Aliquots of this solution were diluted with copper-reduced dilution water to create the test concentrations of 1.0, 10.0, 100, 300, and 1000 mg/L. The control test media was copper-reduced dilution water only.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Age at study initiation: less than 24h
- Feeding during test: the daphnids were not fed during the test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

none

Hardness:

1.1 mmol/L

Test temperature:

20 ± 0.1°C

pH:

The solution pH decreased with increasing test concentration from 8.51 to 4.08, but remained stable in individual test vessels during the test.

Dissolved oxygen:

The oxygen saturation was >3 mg/L in all solutions with the mean value 8.3 mg/L.

Salinity:

no data

Nominal and measured concentrations:

Test concentrations (nominal loadings): 1, 10, 100, 300, and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 60 mL glass beakers; Approximately 50 mL of test solution was added to the test vessels followed by the daphnids.
- Aeration: test vessel were not aerated
- Renewal rate of test solution (frequency/flow rate): the test solutions were not renewed.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:copper-reduced dilution water

OTHER TEST CONDITIONS
- Photoperiod: light/dark cycle of 16/8 hours
- Light intensity: 523-546lux
- Oxygen and pH: the pH and oxygen saturation of the test solutions were measured from pooled vessels at test end.

EFFECT PARAMETERS MEASURED:
After 24 h and 48 h exposure to the test item, the number of immobile daphnids in each beaker was counted. The daphnids were considered to be immobile if they were not able to swim within 15 seconds of gentle agitation of the test vessels. Any abnormalities in appearance and behaviour were also recorded.

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

48.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%CL: 27.6-74.4

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of 50, 100, and 100% compared to the control was observed at 100, 300, and 1000 mg/L after 24 h.
- After 48 h, 75% mortality was recorded at 100 mg/L.
- There was no mortality in the control.
- No signs of disease or stress were observed.
- All surviving specimens gave the impression of healthy condition.

Results with reference substance (positive control):

not examined

Reported statistics and error estimates:

The endpoint of the test was mortality, and the respective LCx, NOEC, and LOEC values were determined. The NOEC and LOEC were determined based on the observation of mortality. Probit analysis was performed to plot dose-response curves and to estimate the EC50, assuming log-normal distribution of the values. The computer software ToxRat® Professional was used for statistical evaluations.

Validity criteria fulfilled:

yes

Conclusions:

Estimated EC50 (calculated): 48.2 mg/L (based on nominal concentration)
NOEC: 10.0 mg/L (nominal concentrations)
Mortality of 50, 100, and 100% compared to the control was observed at 100, 300, and 1000 mg/L after 24 h. After 48 h, 75% mortality was recorded at 100 mg/L. There was no mortality in the control. No signs of disease or stress were observed. All surviving specimens gave the impression of healthy condition.

Reference 2

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:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Dihydrogen hexafluorotitanate is an inorganic substance which will rapidly dissociate into fluoride, potassium and titanium ions upon dissolution in the environment or the human body, and so, similar toxicological properties can be assumed. However, titanium ions do not remain in solution, only fluoride ions do. The approach follows scenario 1 of the RAAF (ECHA 2017). For details, see attached Read-Across statement in IUCLID chapter 13.2.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source
Dipotassium hexafluorotitanate (CAS 16919-27-0)
Target
Dihydrogen hexafluorotitanate (CAS 17439-11-1)

3. ANALOGUE APPROACH JUSTIFICATION
Since dihydrogen hexafluorotitanate rapidly dissociates into fluoride, protons and titanium ions upon dissolution in aqueous solutions, such as the environment or human body, and only fluoride but not titanium ions will remain in solution, it can be assumed that toxicity (if any) will be driven by the fluoride anion. The non-common dissociation products, potassium, sodium, or just hydrogen ions, are considered not to influence the (eco)toxicological profile of Ti2-F6 to a significant degree. These ions are present in the environment and in the human body in considerable amounts. Potassium and sodium levels influence multiple physiological processes. The body has mechanisms to protect from the intake of harmful concentrations of those.
This read-across is based on the hypothesis that source and target substances have similar (eco)toxicological properties, because they dissociate to common anion. The target substance dihydrogen hexafluorotitanate and the source substance dipotassium hexafluorotitanate form hexafluorotitanate species in aqueous solution. Hexafluorotitanate is considered to be (eco)toxicologically relevant, whereas potassium ions are essential elements and practically non-toxic.
For additional information, please refer to the attached read-across statement in IUCLID chapter 13.2.

4. DATA MATRIX
Please refer to the attached read-across statement in IUCLID chapter 13.2.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

53.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: converted to the target substance

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

11.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: converted to the target substance

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

111.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: converted to the target substance

Details on results:

- Mortality of 50, 100, and 100% compared to the control was observed at 100, 300, and 1000 mg/L after 24 h.
- After 48 h, 75% mortality was recorded at 100 mg/L.
- There was no mortality in the control.
- No signs of disease or stress were observed.
- All surviving specimens gave the impression of healthy condition.

Results with reference substance (positive control):

not examined

Reported statistics and error estimates:

The endpoint of the test was mortality, and the respective LCx, NOEC, and LOEC values were determined. The NOEC and LOEC were determined based on the observation of mortality. Probit analysis was performed to plot dose-response curves and to estimate the EC50, assuming log-normal distribution of the values. The computer software ToxRat® Professional was used for statistical evaluations.

Validity criteria fulfilled:

yes

Conclusions:

Estimated EC50 (calculated): 48.2 mg/L (based on nominal concentration)
NOEC: 10.0 mg/L (nominal concentrations)
Mortality of 50, 100, and 100% compared to the control was observed at 100, 300, and 1000 mg/L after 24 h. After 48 h, 75% mortality was recorded at 100 mg/L. There was no mortality in the control. No signs of disease or stress were observed. All surviving specimens gave the impression of healthy condition. The EC50 converted to the target substance corresponds to 53.9 mg/L.

Description of key information

The acute toxicity of the structural analogue dipotassium hexafluorotitanate to Daphnia magna was tested according to OECD 203; an EC50 of 53.9 mg/L was recalculated for dihydrogen hexafluorotitanate.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

53.9 mg/L

Additional information

Dihydrogen hexafluorotitanate

The acute toxicity of the structural analogue dipotassium hexafluorotitanate to Daphnia magna was tested according to OECD 202. An EC50 of 53.9 mg/L was recalculated for dihydrogen hexafluorotitanate (conversion from K2TiF6 value and corrected to max. purity). Information on the read-across approach has been attached in IUCLID section 13.2.