TR 136 – Assessment Factors to Derive DNELs – Critical Evaluation of the Status Quo

An ECETOC technical report has reviewed the existing processes used to determine a substance’s ‘derived no-effect level’ (DNEL), defined as the exposure level beneath which a substance does not harm human health. Establishing a chemical’s DNEL is a key step in the safety assessment of a chemical under the EU’s REACH legislation and is derived by extrapolating from experimental data (usually from animal testing) to human exposure using assessment factors (AFs).

The report found differences between The European Chemical Agency’s and ECETOC’s interpretation of some data, as well as how to combine them into appropriate AFs.  Moreover, large quantities of new mammalian toxicity test data have been generated in recent years under the REACH compliance program, pointing to a need to review some AFs and their associated guidance to avoid divergent viewpoints and practices developing. Still, the overall knowledge confirms that the current default approach leads to very cautious DNELs, demonstrating the high level of protection of human health by the regulatory toxicology framework.