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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
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
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
no guideline followed
Principles of method if other than guideline:
The EU RAR summairses a number of non-Guideline studies
GLP compliance:
no
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
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/L.

Validity criteria fulfilled:
not specified
Conclusions:
NOEC values of between 7.1 -226 mg/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/L are reported.

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 hazards on sewage sludge microorganisms.have been identified for both constituents.

As no studies are available calcium fluoride, one data from an OECD 209 study has been collected in HF review (EU RAR, 2001). This value has been used for calcium fluoride:

NOEC (3h) =510 mg/L (based on nominal concentrations of fluoride ions) which is equivalent to an NOEC (3h) of 1048.5 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 value (3h) used for the registered substance is equal to 2207.4 mg/L (based on fluoride equivalent for the reaction mass).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
2 207.4 mg/L

Additional information

The substance is a reaction mass of calcium fluoride and calcium sulfate and calcium carbonate. No studies are available on the substance itself, nor on calcium fluoride. However, one guideline-compliant study (OECD 209) is available in the EU RAR report (2001) of hydrogen fluoride with a NOEC (3h) of 510 mg/L (fluoride ions) which is equivalent to 1048.5 mg/L for CaF2.

Regarding the 2 others constituents of the substance, calcium sulfate and calcium carbonate, they are known to be ubiquitous in the environment and essential to living organims. Nevertheless, studies are available for both constituents.

An reliable OECD guideline Activated Sludge Respiration Inhibition (ASRIT) study has been performed on calcium sulfate dihydrate (Youngs 2010). Sewage sludge microorganisms were exposed to nominal concentrations of 32, 100, 320 and 1000 mg/L for 3 h. The 3 h EC50 value was >1000 mg/L and the NOEC was 1000 mg/ (the highest dose tested).

Regarding calcium carbonate, the nano form of calcium carbonate was tested because this form was anticipated to represent the worst case as it is likely to be more soluble than the bulk form due to the smaller particle size and hence greater surface area. However, the results are directly applicable to the bulk form of calcium carbonate. The key study (Youngs, 2010) was performed to OECD Guideline 209 and in accordance with GLP and was therefore assigned a reliability of 1.The study assessed the toxicity of calcium carbonate (nano) to activated sewage sludge at nominal test concentrations of 10, 32, 100, 320 and 1000 mg/L.No toxic effects were seen at any concentration of calcium carbonate (nano) tested. Hence, the 3 h EC50 was >1000 mg/L and the NOEC was 1000 mg/L. Calcium carbonate (nano) is therefore not toxic to aquatic microorganisms up to a concentration of 1000 mg/L. Evidence of undissolved test material was observed in some of the test vessels suggesting that the concentrations tested exceeded the maximum solubility of calcium carbonate in water.

Using a weight of evidence approach for the 3 constituents of the substance, calcium fluoride is the main constituent and is used as a worst case, witha NOEC (3h) of 1048.5 mg/L. The 2 others constituents of the substance, calcium sulfate and calcium carbonate, are ubiquitous in the environment and essential to living organims : no hazards have been identified for both constituents based on data available.

As calcium fluoride is present at 47.5% in the reaction mass of calcium fluoride, calcium sulfate and calcium carbonate, the NOEC value (3h) used for the registered substance is equal to 2207.35 mg/L (based on fluoride equivalent for the reaction mass).