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Long-term toxicity to fish

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Endpoint:
long-term toxicity to fish, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Dihydrogen hexafluorotitanate is an inorganic substance which will rapidly dissociate into fluoride, hydrogen and titanium ions upon dissolution in the environment. However, hydrogen and titanium ions do not remain as such in solution, only fluoride ions do. The approach follows scenario 1 of the RAAF (ECHA 2017).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source
fluoride salts (various)
Target
Dihydrogen hexafluorotitanate (CAS 17439-11-1)

3. ANALOGUE APPROACH JUSTIFICATION
The hydrogen ion attaches to a hydroxide ion to form a water molecule. The analysis of dissolved titanium levels in aquatic toxicity test solutions for algae, daphnia and fish according to OECD 201, 202 and 203 (Schlechtriem, 2013a, b; Teigeler, 2013) indicates that up to a loading of 100 mg/L dipotassium hexafluorotitanate, very low levels of titanium (often < 10% or even 5%) remain in solution at environmentally relevant pH while nearly all of the fluoride (often more than 95 %) could be recovered. Thus, regarding the environmental fate and toxicity of dihydrogen hexafluorotitanate, it can be assumed that toxicity (if any) will be driven by the fluoride anion. Therefore, full read-across to potassium fluoride (CAS #7789-23-3) and other fluorides based upon a molecular weight conversion is justified.

4. DATA MATRIX
see attached read-across statement in section 13.2
Reason / purpose for cross-reference:
read-across source
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
9.412 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride ion F-
Basis for effect:
mortality
Details on results:
In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.
Results with reference substance (positive control):
No results reported.
Reported statistics and error estimates:
No results reported.

In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.

Conclusions:
In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water. Converted to the target substance this value corresponds to 9.412 mg/L.
Executive summary:

In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water. Converted to the target substance this value corresponds to 9.412 mg/L.

Endpoint:
long-term toxicity to fish, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study summarised in ICD and EU RAR
Qualifier:
no guideline followed
Principles of method if other than guideline:
21-day fish toxicity study
GLP compliance:
no
Specific details on test material used for the study:
Sodium fluoride is water soluble and will rapidly dissociate under the aqueous conditions of the test to form sodium and fluoride ions.
Analytical monitoring:
yes
Details on sampling:
No further details in review
Vehicle:
not specified
Details on test solutions:
No further details in review
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
No further details
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not relevant
Hardness:
soft water (12 mg CaCO3/l)
Test temperature:
Not reported
pH:
Not reported
Dissolved oxygen:
Not reported
Salinity:
Not reported
Nominal and measured concentrations:
Measured concentration
Details on test conditions:
The test was conducted in very soft (12 mg CaCO3/l) natural water with daily renewal of the test water.
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
4 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: fluoride ion F-
Basis for effect:
mortality
Details on results:
In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.
Results with reference substance (positive control):
No results reported.
Reported statistics and error estimates:
No results reported.

In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.

Conclusions:
In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.
Executive summary:

In a 21 day test with Oncorhynchus mykiss a LC5 value of 4 mg/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.

Description of key information

Since dihydrogen hexafluorotitanate rapidly dissociates into fluoride, hydrogen and titanium ions upon dissolution in the environment, and only fluoride but not hydrogen and titanium ions will remain as such in solution, it can be assumed that toxicity (if any) will be driven by the fluoride anion. Therefore, full read-across of chronic toxicity data for fish of potassium fluoride (CAS #7789-23-3) and other fluorides based upon a molecular weight conversion (and correction to max. purity) is justified. The LC5 of 4 mg F/L derived for Oncoryhychus mykiss in a 21-d test with sodium fluoride (LC5 = 4 mg F/L ), results in an LC5 of 9.4 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
9.4 mg/L

Additional information

Dihydrogen hexafluorotitanate


For reasons of animal welfare, a repetition of the study with the test material is omitted and the existing data with potassium fluoride are considered sufficiently meaningful, also because the algae seems to be the most sensitive species based on the available data and thus there is no further benefit with regard to the estimation of the chronic toxicity of the test material.


Since dihydrogen hexafluorotitanate rapidly dissociates into fluoride, hydrogen and titanium ions upon dissolution in the environment, and only fluoride but not hydrogen and titanium ions will remain as such in solution, it can be assumed that toxicity (if any) will be driven by the fluoride anion. Therefore, full read-across of chronic toxicity data for fish of potassium fluoride (CAS #7789-23-3) and other fluorides based upon a molecular weight conversion (and correction to max. purity) is justified (see below).


 


Sodium fluoride


In a 21 day test with Oncorhynchus mykiss, an LC5 value of 4 mg F/L was reported (actual concentration). This value is considered to be equivalent to the NOEC for mortality. The test was conducted in very soft (12 mg CaCO3/L) natural water with daily renewal of the test water.