Under REACH, the Downstream User (DU) is obliged to check compliance with the Exposure Scenario (ES) forwarded by the Registrant. The information on Operational Conditions (OCs) and Risk Management Measures (RMMs) given in the ES should be compared with the actual OCs and RMMs of the DU. OCs/RMMs may not always be completely identical with the OCs/RMMs specified in the ES, and may actually deviate from them. When one or more of the actual OC and RMM differ from those of the ES, it is not immediately apparent whether the use is still in compliance with the ES. In all cases, the DU should still be able to ascertain that he is in compliance with the ES.
For this situation, the registrant can provide scaling rules as part of the ES to help DUs to check compliance with the ES and to increase the flexibility of ESs for a wider range of downstream users. EUROMETAUX and ARCHE have developed a DU scaling tool (originally initiated by EURAS) for compliance checking with the environmental ES of metals. The DU scaling tool is based on the spreadsheet version of EUSES.

In the registrant-interface, the generic default OCs and RMMs can be entered. Some of them are very relevant for metals, such as the possibility to provide measured regional concentrations and solid-water partition coefficients.
In the simple and easy-to-use DU-interface, key OC and RMM can be changed according to the site-specific OC and RMMs of the DU. This includes general parameters as release factors, dilution, presence/absence of municipal sewage treatment plant, etc... It also allows the DU to enter bioavailability-corrected PNECs (Predicted No Effect Concentrations), for those metals for which relevant models are available.
In the background, the full EUSES model is run to calculate exposure and risks.
The resulting risk characterisation ratios allow the DU to assess safe use. In this way, the DU scaling tool enables the DU to check compliance with the ES if his OCs or RMMs differ from those in the ES.

How does it work??
1. The registrant fills out the sheet ‘ES input by Registrant' with metal-specific parameters (e.g. substance identification information and default operational conditions and RMMs). A database with some default information is currently built up.
2. The registrant provides the ES and calculator to the Downstream User
3. The Downstream User edits the sheet "ES modifier by DU (Sheet 1)" if he is not compliant with the proposed ‘default' ES. He can adjust some site-specific information like operational conditions, risk management measures. As a result, the tool will issue some statements indicating safe/non safe uses (green/red marked)
4. In case the Downstream User is still not compliant with the default ES and Sheet 1, he is requested to edit sheet "ES modifier by DU (Sheet 2)"

Important notes:

• The tool is available for download and own use. There are two versions available depending on the operating system and office/excel version you are using. Extension xlsx is the Excel 2007 version and the regular extension xls is the Excel 2003 version
• As the tool is still being road tested, any feedback is highly appreciated (please send your comments to Dr Frederik Verdonck at frederik.verdonck@arche-consulting.be mentioning the operating system and office/excel version, thanks!!).