DNEL Derivation Guidance

The ECETOC DNEL Derivation Guidance (2010) – which provides the technical underpinnings by which many/most of industry DNELs (derived no-effect levels) were developed in 2010 and post-2010 – are using guidance factors that differ from those in ECHA REACH guidance, and Member States and ECHA generally challenge these when used. In many cases, the ECETOC guidance factors have been applied but with insufficient supporting documentation (only citation to ECETOC report, rather than substance specific data to support).

Within ECETOC, several companies have formed a Task Force aimed at updating the original guidance on assessment factors based on the latest scientific data and experience both internationally and with the REACH Regulation.

REACH is a precautionary regulation that is intended to provide a high level of protection for human health (and the environment) while maintaining cost of the competitiveness and sustainability of the EU chemicals’ market. It achieves this high level of protection in substance risk assessment by calling for the use of conservative, default Assessment Factors (AFs) when developing Derived No Effect Levels (DNELS) for non-cancer endpoints, first-tier exposure assessment tools. Individually these conservative assumptions are reasonable. However, when used in combination in the risk assessment they are multiplicative resulting in a significant over prediction of the actual risk for many substances. This significant over prediction results in the need for additional resources from industry experts and regulators in order to refine these assessments. These refinements include the development and use of chemical specific AFs and the use of higher tier exposure assessment tools to more accurately predict risk.

Experience gained during registration has demonstrated that the burden of proof necessary to justify to ECHA the use of chemical specific AFs is set so high that justification of these factors will be unachievable for all but a few data rich substances. This situation is compounded by the lack of clear and practical guidance on how to develop chemical specific AFs and a lack of such expertise within the chemical industry.

While higher tier exposure assessment tools are available and experience with these is growing it is unlikely that these alone will be sufficient to correct the conservative AFs that are recommended today, particularly for substances of the lower volume bands which attract the highest default AFs (based on e.g. study duration).

The development of guidance by a scientific body such as ECETOC would help to increase the quality and consistency of dossiers thereby leading to a reduced burden in both parties, but would also indirectly contribute to maintaining EU competitiveness.