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Environmental fate & pathways

Phototransformation in water

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Description of key information

Phototransformation in water is expected to be of minor importance since formaldehyde is rapidly converted to a glycol.

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Additional information

In water, formaldehyde is rapidly hydrated to form methylene glycol. Equilibrium almost totally favours the glycol. Incorporated into atmospheric water, formaldehyde or its hydrate can undergo oxidation. When incorporated from air into cloud water, fog water or rain, formaldehyde can react with aqueous hydroxyl radicals in the presence of oxygen to produce formic acid, water and hydroperoxide (aqueous). The formaldehyde glycol can also react with ozone. In comparison to its biodegradability, however, photochemical degradation of formaldehyde in the aqueous phase does not appear to be relevant. Furthermore, studies on the phototransformation in water or soil are not required for a registration under REACH.