Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

According to the REACH Regulation, an adsorption/desorption study does not need to be conducted if based on the physicochemical properties the substance can be expected to have a low potential for adsorption (Annex VIII, column 2 adaptation).

Considering its high water solubility, NaOH is not expected to bioconcentrate in organisms. High water solubility and low vapor pressure indicate that NaOH will be found predominately in the aquatic environment.

The 73% aqueous solution of NaOH at ambient temperatures is a highly viscous, gelatinous material and without additional dilution (precipitation), it is not expected to infiltrate soil to any significant extent. The 50% aqueous solution of NaOH is liquid and is expected to infiltrate soil to a measurable degree. As the dilution of NaOH
increases, its speed of movement through soil increases. During movement through soil, some ion exchange will occur.
Also, some of the hydroxide may remain in the aqueous phase and will move downward through soil in the direction of
groundwater flow (EU RAR 2007, section 3.1.3, page 24).