Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Reaction mass of calcium fluoride, calcium sulfate and calcium carbonate is an inorganic salt and will dissociate in water at environmentally relevant pH to form calcium, fluoride, sulfate and carbonate ions.

Additional information

According to Annex VIII, section 9.2.2.1 of Regulation No. 1907/2006, information regarding the hydrolysis of the registered substance is required. However, such a study is not applicable to reaction mass of calcium fluoride, calcium sulfate and calcium carbonate for the following reasons: the substance is an inorganic substance and therefore does not undergo hydrolysis.

In the environment, the substance will dissociate into calcium, fluoride, sulfate and carbonate ions. These ions are naturally ubiquitous in the environment; Calcium fluoride is of very low water solubility and will therefore dissociate to a very limited extent in aqueous conditions to form calcium and fluoride ions. The liberated ions will be indistinguishable from those natrurally present in the environment and will be further transformed in water, sediment and soil to a variety of other calcium and fluorine-containing compounds. Calcium will be assimilated by species present in the water and is necessary to maintain a good chemical balance in soils, water and plants and sulfate will either become part of the sulfur cycle or be assimilated by microorganisms and plants and carbonate will become part of the carbon cycle.  Data from Allan DJ (1995) indicate that most natural waters contain various bicarbonate and carbonate compounds, originating from dissolution of sedimentary rocks.  Streamwater usually contains bicarbonates and carbonates and carbonic acid readily dissolves CaCO3 rocks, forming Ca(HCO3)2. The resulting streamwater is a solution of CO2, H2CO3, HCO3- and CO3^2- ions forming an effective buffer system that resists change in pH.  The relative proportions of CO2, H2CO3, HCO3-and CO3^2- are pH dependent. At a pH below 4.5, only CO2 and H2CO3 are present and almost no HCO3- or CO3^2- is found. At higher pH values dissociation of H2CO3 occurs, HCO3-and CO3^2- are present and CO2 and H2CO3 are no longer detectable. At intermediate pH values, HCO3- predominates. Above a pH of about 8.3, HCO3- also declines with formation of CO3^2-. The dissociation dynamics are influenced by both temperature and ionic concentrations.  Therefore, the chemistry of carbonate in water is clearly understood.  References:  Allan DJ (1995), Stream Ecology: Structure and function of running waters, Published by Chapman and Hall.

Considering the current knowledge about the constituents of the substance (low solubility in water of calcium fluoride and calcium carbonate), conducting new studies are considered scientifically unjustified.