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Toxicity to terrestrial arthropods

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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.
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.

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
Dipotassium hexafluorotitanate is an inorganic substance which will rapidly dissociate into fluoride, potassium and titanium ions upon dissolution in the environment. However, titanium ions do not remain 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
Dipotassium hexafluorotitanate (CAS 1619-27-0)

3. ANALOGUE APPROACH JUSTIFICATION
Since dipotassium hexafluorotitanate rapidly dissociates into fluoride, potassium and titanium ions upon dissolution in the environment, 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. 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 1685.0 mg/kg for dipotassium 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 dipotassium hexafluorotitanate rapidly dissociates into fluoride, potassium and titanium ions upon dissolution in the environment, 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. 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 1685.0 mg/kg for dipotassium hexafluorotitanate.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:
1 685 mg/kg soil dw

Additional information

Dipotassium hexafluorotitanate


Since dipotassium hexafluorotitanate rapidly dissociates into fluoride, potassium and titanium ions upon dissolution in the environment, 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. Therefore, full read-across of soil toxicity data of potassium fluoride (CAS #7789-23-3) and other fluorides based upon a molecular weight conversion 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).