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Ecotoxicological information

Toxicity to terrestrial arthropods

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Reference
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:
read-across: supporting information
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 (migrated information):
No further details.
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 the 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:
not specified
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

Calcium fluoride is the main constituent of the substance, so its worst case value was chosen for the registered dossier. The 2 others constituents of the substance, calcium sulfate and calcium carbonate, are ubiquitous in the environment and essential to living organims. No studies are available for CaSO4 and CaCO3 but no hazards are expected.

As no studies are available for calcium fluoride, one data published by Beyer et al. (1987) on toxicity of sodium fluoride on Porcellio scaber has been used for the dossier : 

NOEC (126d) = 800 mg/kg soil dw (concentrations of sodium fluoride) which is equivalent to an NOEC (126d) of 744 mg/L for CaF2.

As calcium fluoride is present at 47.5% in the reaction mass of calcium fluoride, calcium sulfate and calcium carbonate, the NOEC (126d) used for the registered substance is equal to 1566.3 mg/kg.

Based on this NOEC value, the registered substance was found to have no effect on arthropods.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil dwelling arthropods:
1 566.3 mg/kg soil dw

Additional information

The substance is a reaction mass of calcium fluoride and calcium sulfate and calcium carbonate. No studies on soil arthropods toxicity are available on the substance itself, nor on the main constituent : calcium fluoride. However, one data published by Beyer et al. (1987) on toxicity of sodium fluoride on Porcellio scaber in leaf litter has been used for the dossier. 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). The toxicity of sodium fluoride to Porcellio scaber was investigated over a period of 126 d with a NOEC value (126d) of 800 mg/kg (equivalent to 744 mg/kg of CaF2) : the toxicity was only observed at very high concentrations. 

Regarding the 2 others constituents of the substance, calcium sulfate and calcium carbonate, they are known to be ubiquitous in the environment and essential constituents to living organims, including arthropods. Calcium sulfate, calcium and sulfate ions are ubiquitous in the environment. Calcium is an important constituent of most soils and the minerals found in soil are mostly compounds of calcium with other substances. Furthermore, calcium sulfate, as Gypsum, is used as an inorganic fertiliser to improve soil quality. Calcium salts are also an ingredient of earthworm feed. Short or long term testing of CaSO3 on terrestrial arthropods is considered to be unnecessary. Calcium carbonate and calcium and carbonate ions are ubiquitous in the environment and are found naturally in soil, water and sediment. Calcium is an important constituent of most soils and the minerals found in soil are mostly compounds of calcium with other substances. Furthermore, calcium carbonate is used as an inorganic fertiliser to improve soil quality, both pH and structure and guarantees an adequate supply of calcium to plants. Given the extensive and continued use of calcium carbonate as a constituent of fertiliser and its natural occurrence in the environment, it is considered that calcium carbonate would not have a detrimental effect on soil macroorganisms. Therefore, the performance of short- or long term toxicity tests on terrestrial arthropods is scientifically unjustified.

Using a weight of evidence approach for the 3 constituents of the substance, calcium fluoride is the main constituent and showed a low toxicity with aNOEC(126d) of 744 mg/kg dw. The 2 others constituents of the substance, calcium sulfate and calcium carbonate, are ubiquitous in the environment and essential to living organims : no hazards are expected for both constituents.

As calcium fluoride is present at 47.5% in the reaction mass of calcium fluoride, calcium sulfate and calcium carbonate, the NOEC (126d) used for the registered substance is equal to 1566.3 mg/kg. Based on this NOEC value, the registered substance was found to have no effect on arthropods.