Dihydrogen hexafluorotitanate(2-)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Remarks:

and other

Type of information:

other: review

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms

Qualifier:

no guideline followed

Principles of method if other than guideline:

The EU RAR summairses a number of non-Guideline studies

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Sodium fluoride is water soluble and will rapidly dissociate under the aqueous conditions of the test to form sodium and fluoride ions. The toxicity of sodium fluoride is essentially due to fluoride ions and therefore is appropriate for read-across to KF.

Analytical monitoring:

not specified

Test organisms (species):

other: various

Test type:

static

Water media type:

freshwater

Remarks on exposure duration:

see details

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Chlomonas paramaecium

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

101 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Entosiphon sulcatum

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: inhibition of acid formation from glucose

Remarks on result:

other: Eschericia coli

Duration:

20 h

Dose descriptor:

NOEC

Effect conc.:

7.1 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Uronema parduczi

Duration:

28 h

Dose descriptor:

NOEC

Effect conc.:

226 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of feed uptake

Remarks on result:

other: Microregma heterotoma

Duration:

16 h

Dose descriptor:

NOEC

Effect conc.:

231 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Pseudomonas putida

The EU RAR reports NOEC values of between 7.1 -226 mg F/L.

Validity criteria fulfilled:

not specified

Conclusions:

NOEC values of between 7.1 -226 mg F/L are reported.

Executive summary:

The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 -226 mg F/L are reported.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Remarks:

and 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
sodium fluoride (CAS 7681-49-4)
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. The lowest available NOEC of 7.1 mg F/L results in a NOEC for microbial toxicity of 10.2 mg/L dihydrogen hexafluorotitanate.

4. DATA MATRIX
see attached read-across statement in section 13.2

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

83 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Chlomonas paramaecium

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

101 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Entosiphon sulcatum

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: inhibition of acid formation from glucose

Remarks on result:

other: Eschericia coli

Duration:

20 h

Dose descriptor:

NOEC

Effect conc.:

7.1 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Uronema parduczi

Duration:

28 h

Dose descriptor:

NOEC

Effect conc.:

226 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Inhibition of feed uptake

Remarks on result:

other: Microregma heterotoma

Duration:

16 h

Dose descriptor:

NOEC

Effect conc.:

231 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: Pseudomonas putida

The EU RAR reports NOEC values of between 7.1 -226 mg F/L.

Validity criteria fulfilled:

not specified

Conclusions:

NOEC values of between 7.1 -226 mg F/L are reported.

Executive summary:

The EU RAR summarises and reviews the available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 -226 mg F/L are reported.

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 microbial toxicity data 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). The lowest available NOEC of 7.1 mg F/L for toxicity of fluoride to Uronema parduszi results in a NOEC for microbial toxicity of 16.74 mg/L dihydrogen hexafluorotitanate.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

16.74 mg/L

Additional information

Dihydrogen hexafluorotitanate

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 microbial toxicity data 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). The lowest available NOEC of 7.1 mg F/L results in a NOEC for microbial toxicity of 16.74 mg/L dihydrogen hexafluorotitanate.

 

Sodium fluoride

The guideline-compliant Bayer study reports a 3 -hour NOEC of 510 mg/L for activated sludge. The EU RAR summarises and reviews the other available data on the toxicity of fluoride to aquatic microorganisms; NOEC values of between 7.1 - 226 mg/L are reported.