Dihydrogen hexafluorotitanate(2-)

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Older, non-GLP publication.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Not applicable

GLP compliance:

no

Application method:

soil

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 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:

no

Details on sampling:

Litter was collected from eight sites at distances as far as 33 km from an Al reduction plant in western Tennessee. Soil was collected at a level of 0 to 5 cm and 5 to 15 cm.

Vehicle:

no

Details on preparation and application of test substrate:

The main part of the study involves deducing whether the content of fluoride in the litter is related to the distance from thr Al reduction plant. In one test, sodium fluoride is added to the litter to determine the effect on mortality.

Test organisms (species):

Porcellus scaber

Details on test organisms:

No further details on test organisms.

Study type:

field study

Limit test:

no

Post exposure observation period:

No post observation period.

Test temperature:

Not stated

pH (if soil or dung study):

Not stated

Humidity:

Not stated

Photoperiod and lighting:

Not stated

Details on test conditions:

The test involves determining whether there is a link between distance from the Al reduction plant and concentration of fluoride ions in the soil. Litter was collected from eight sites at distances as far as 33 km from an Al reduction plant in western Tennessee. Soil was collected at a level of 0 to 5 cm and 5 to 15 cm. To determine the effect of increased fluoride concentration on mortality, a sample of litter was spiked with sodium fluoride and the mortality rate monitored.

Nominal and measured concentrations:

measured.

Reference substance (positive control):

no

Duration:

126 d

Dose descriptor:

NOEC

Effect conc.:

800 mg/kg bw

Basis for effect:

mortality

Details on results:

Litter was collected from eight sites at various distances away from the plant. Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from our study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

Results showed that litter collected far from the plant had a lower fiber content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg).

Validity criteria fulfilled:

not applicable

Conclusions:

Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. In a bioassay of litter from our study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

Executive summary:

The effects of fluoride concentration were investigated on the numbers of Porcellio scaber in leaf litter. Leaf litter was collected from eight sites at various distances away from an aluminium reduction plant. Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

Reference 2

Endpoint:

toxicity to terrestrial arthropods: short-term

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
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, the NOEC of 800 mg F/kg for the long-term (126 days) toxicity of sodium fluoride to Porcellio scaber is read-across resulting in a NOEC of 1150.3 mg/kg for dihydrogen hexafluorotitanate.

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

Reason / purpose for cross-reference:

read-across source

Duration:

126 d

Dose descriptor:

NOEC

Effect conc.:

800 mg/kg bw

Basis for effect:

mortality

Details on results:

Litter was collected from eight sites at various distances away from the plant. Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from our study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

Results showed that litter collected far from the plant had a lower fiber content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg).

Validity criteria fulfilled:

not applicable

Conclusions:

Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. In a bioassay of litter from our study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

Executive summary:

The effects of fluoride concentration were investigated on the numbers of Porcellio scaber in leaf litter. Leaf litter was collected from eight sites at various distances away from an aluminium reduction plant. Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. Total acid extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable F-. When F- was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg.

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, the NOEC of 800 mg F/kg for the long-term (126 days) toxicity of sodium fluoride to Porcellio scaber is read-across resulting in a NOEC of 1885.7 mg/kg for dihydrogen hexafluorotitanate (based upon a molecular weight conversion and correction to max. purity).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:

1 885.7 mg/kg soil dw

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 soil 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).

 

Sodium fluoride

The effects of fluoride concentration were investigated on the numbers of Porcellio scaber in leaf litter. Leaf litter was collected from eight sites at various distances away from an aluminium reduction plant. Results showed that litter collected far from the plant had a lower fibre content, was more sapric and was less acid. Total acid extractable fluoride in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from study sites, woodlice (Porcellio scaber) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid extractable fluoride. When fluoride was added in the form of NaF to the litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg (Beyer et al, 1987).