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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Key value for chemical safety assessment

Additional information

The substance reacts with water. The water soluble reaction product is a multi-constituent substance:

Reaction mass of disodium metasilicate and sodium hydroxide(EC 910-245-3)

Sodium Hydroxide: Source - the sodium hydroxide summary risk assessment report JRC EC 2008

In water (including soil or sediment pore water), NaOH is present as the sodium ion (Na+) and hydroxyl ion (OH-), as solid NaOH rapidly dissolves and subsequently dissociates in water. If emitted to soil, sorption to soil particles will be negligible. Depending on the buffer capacity of the soil, OH- will be neutralised in the soil pore water or the pH may increase.

Bioaccumulation in organisms is not relevant for NaOH.

Silicates:

Toxicokinetic data on vertebrates revealed a low potential for bioaccumulation. Ingested soluble silicates are excreted via urine and to a lesser extent via the faeces. Markedly increased and rapid urinary excretion of silica was observed when soluble sodium silicates were administered to rats (Benke & Osborn 1979), dogs (King et al. 1933), cats (King & McGeorge 1938) and guinea pigs (Sauer et al. 1959). The urinary silicon excretion half-life after administration of sodium silicate to rats via stomach tube was 24 h (Benke & Osborn 1979).