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Environmental fate & pathways

Endpoint summary

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Description of key information

Fate in the environment

Endpoints of environmental fate and pathways are attached with a waiving argument for the following reasons:

Silicon is the second most abundant element in the earth’s crust mass (approx. 28 %) after oxygen. It appears as complex silicate minerals in soils and sediments, as the oxide (silica, SiO2) in crystalline form in rocks, soils and sand, and as biogenic silica in organisms such as diatoms, radiolarians or silicoflagellates and in plants such as grass, rushes, rice or sugar cane.

Synthetic amorphous silica and silicates released into the environment are expected to be distributed mainly into soils and sediments, weakly into water and probably not at all in the air due to their physico-chemical properties, low water solubility and very low vapour pressure.

Synthetic amorphous silica and silicates released into the environment are expected to combine indistinguishably with the soil or sediment due to their similarity with inorganic soil/sediment matter and will be subjected to natural processes under environmental conditions (cation exchange, dissolution, sedimentation).

Based on the chemical nature of synthetic amorphous silica and silicates (inorganic structure and chemical stability of the compound: Si-O bond is highly stable), no photo- or chemical degradation is expected. Biodegradation is not applicable to these inorganic substances.

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