Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

According to REACH Annex XI, section 2 testing for specific endpoints can be omitted, if the test is technically not possible to conduct as a consequence of the properties of the substance. The molecular structure of the test substance does not contain any hydrolysable functional groups, such as esters or amides. The test on the hydrolysis of the test substance could therefore not be performed. In contact with water Mg(OH)2dissociates into Mg2+and 2 x OH-.

Furthermore, Magnesium hydroxide has a very low propensity for adsorption to sediment based on a derived Kd value of 1.65. The Forum of European Geological Surveys (FOREGS) Geochemical Atlas of Europe ('Salminen, R. (ed.) 2005) [1]provided paired sediment-water concentrations of Magnesium and Magnesium oxide from which sediment partition coefficients (Kd values) could be derived. The median Kd value of 1.65 L/kg will be used for the risk assessment. This indicates that Magnesium hydroxide has a low sediment adsorption potential. The test on biodegradation in water was not conducted as, according to REACH Regulation 1907/2006 the study does not need to be conducted if the substance is inorganic.

 Magnesium hydroxide has no bioaccumulation potential and according to Annex IX of REACH Regulation 1907/2006, this study does not need to be conducted if the substance has a low potential to bioaccumulate. As Magnesium hydroxide is an inorganic substance, it is not likely to cross biological membranes and will therefore not bioaccumulate. Based on this, this study is not required.

Additional information