Magnesium fluoride

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

In accordance with section 1 of REACH Annex XI, the study does not need to be conducted as in water, magnesium fluoride quickly dissociates. In addition, In accordance with column 2 of REACH Annex VIII, the study is not needed since the substance is inorganic solid. The hydrolysis is not a relevant fate process for the inorganic substance and the bioavailable constituents of the substance.
Based on the known chemistry of alkaline earth metals, MgF2 is a poorly soluble substance composed of 2 components (Mg and F) with different solubility. Magnesium is found in seawater and plant and animal tissues and is an essential element for human survival. Several enzymatic reactions in the body and fysiological processes (such as muscle contraction, neuronal transmission) are dependent on the availability of magnesium. (Patty’s Toxicology, 2001). Fluoride is present in small concentrations in practically all soils, water supplies and plants. Fluoride levels in surface waters generally range from 0.01 to 0.3 mg/L. Seawater contains more fluoride than fresh water, with concentrations ranging from 1.2 to 1.5 mg/litre. 
A complete reaction can occur only high temperature. It has been investigated by Donald R. Messier (1965):
1. MgF2+H20 --> MgF2.H2O
2. MgF2.H2O --> Mg(OH)F+ HF
3. Mg(OH)F --> MgO + HF
There is a primary formation of a hydroxyfluoride complex stable (1 and 2) and decomposition of the hydroxyfluoride complex to form products (3). In general, dilution and dispersion in the environment will favour the formation of hydrolytic species.