REACH Metals Gateway

Rapid Removal

A decision on whether or not the substance is classified as toxic for the aquatic environment will be made by comparing aquatic toxicity data and solubility data.

Solubility for metals and inorganic compounds, relates to the level of the metal ion that will be present in the solution following the addition of the metal and/or its compounds. It will largely be determined by two processes: the extent to which it can be dissolved, i.e., its water solubility, and the extent to which it can react with the media to transform to water soluble forms. The rate and extent at which this latter process, known as ‘transformation’ for the purposes of this guidance, takes place can vary extensively between different compounds and the metal itself, and is an important factor in determining the appropriate hazard class.

The OECD transformation and dissolution protocol (TDP, OECD 2001), is an effective approach to test the solubility (or lack) of metal and inorganic compounds in standard conditions. It allows to compare the soluble fraction (after a standard period of 7 and 28 days) with the subsequent acute and chronic Ecotoxicity Reference Values.

For the classification of organics, degradation is considered when establishing the classification. The term ‘degradation’ refers to the decomposition of organic molecule and as such cannot be applied to metals. Rather, the substance may be transformed by normal environmental processes to either increase or decrease the bioavailability of the toxic species (‘transformation’). 

Environmental transformation processes of metals and metal compounds to non-bioavailable forms influences classification as hazardous to the aquatic environment, questions surrounding removal from the water column and whether such mechanisms should be taken into account for aquatic hazard classification has been open for many years.

Industry has developed both the Unit World Model (UWM) and the Extended Transformation/Dissolution protocol (T/Dp-E) which respectively model and measure both removal and the absence of remobilisation due to resuspension, with the aim of making the concept (also known as ‘rapid removal’) applicable for the EU CLP.


These models and approaches were discussed with authorities during the following workshops: 

Rapid Removal Information Session

Workshop on progressing the Rapid Removal concept for metals classification/hazard identification

ECHA - Helsinki, 8 February 2019

Summary report

Rapid Removal workshop Agenda


Meeting presentations:


What happened since 2012 - Hugo Waeterschoot

1- Richard Carbonaro

2- Emily Rogevich

3- Philippa Huntsman

4- Stijn Baken

5- Kevin Rader


Reference material:

Report from the Workshop on the validity of the use of the concept of ‘rapid removal’ on 8th February 2012


Last page update: 30 October 2023