Hexafluorosilicic acid

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to non-target arthropods on natural substrate (NTA other than pollinators)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

see read across justification

Reason / purpose for cross-reference:

read-across source

GLP compliance:

no

Duration:

126 d

Dose descriptor:

NOEC

Effect conc.:

800 mg/kg bw

Remarks on result:

other: see details on results

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 F-/kg.

The NOEC is 800 mg F-/kg.

Applying the conversion factor from F- to hexafluorosilicic acid, the NOEC corresponds to 1008 mg hexafluorosilicic acid/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 F-/kg.

The NOEC is 800 mg F-/kg.

Applying the conversion factor from F- to hexafluorosilicic acid, the NOEC corresponds to 1008 mg hexafluorosilicic acid/kg.

Description of key information

The effects of fluoride concentration were investigated on the numbers of Porcellio scaber in leaf litter. 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 F-/kg. The NOEC is 800 mg F-/kg. Applying the conversion factor from F- to hexafluorosilicic acid, the NOEC corresponds to 1008 mg hexafluorosilicic acid/kg.

Key value for chemical safety assessment

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

1 008 mg/kg soil dw

Additional information

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 F-/kg.

The NOEC is 800 mg F-/kg.

Applying the conversion factor from F- to hexafluorosilicic acid, the NOEC corresponds to 1008 mg hexafluorosilicic acid/kg.