# Lecture at SETAC Europe Annual Meeting 2021

**Datum/Tijd**

Date(s) - 03 mei 2021 - 06 mei 2021*08:00 - 16:30*

**Categorieën**

Abstract:

The environmental risk assessment of new chemicals conducted under the REACH framework and elsewhere requires input of two types of criteria: an estimate of the expected concentration in environmental compartments (PEC) and the expected threshold level for ecological effects (NEC). The risk is then estimated from PEC/NEC. However, both PEC and NEC come with considerable uncertainties, i.e. they are stochastic variables and follow a probability density distribution. Rather than comparing the mean PEC with the mean NEC, one would like to take the variation in both criteria into account. This can be done by considering the convolution integral of the PEC and the NEC distribution. There is a straightforward formula for this, which was derived before by Aldenberg *et al.* (2002). This has now been implemented in the SIMPLEBOX framework in the module SimpleBoxTreat4SOLUTIONS and is suggested for consideration in the EUSESvs2 and EUSESvs3 risk assessment packages. In the SOLUTIONS project we have made sample calculations derived from distributions of possible exposure concentrations in EU water as well as data on distributions of EC50 values for aquatic organisms, for the same chemicals. The convolution integral, which we call “toxic pressure” (TP) is estimated for a large number of chemicals. We propose a cut-off value of 10^{–6} as a negligible risk threshold. Our new method avoids the disputable properties of the commonly used risk quotient and includes the variation and uncertainty in both exposure and effect assessment. The method is proposed for inclusion in the REACH framework.