Risk assessment approaches for PBT/vPvB or POPs


The Task Force resulted in the Technical Report no.112: Refined Approaches for Risk Assessment of PBT/vPvB Chemicals (Published October 2011)

Many national, or regional, regulations and regional or global conventions exist that identify and prioritise substances of concern based on their hazardous properties. The criteria for identifying such substances under these various instruments are not the same but have many similarities through cut-off values associated with a chemical’s persistence (P), bioaccumulation (B) and toxicity (T). Criteria for PBT first came on the agenda within the EU in the revision of the Technical Guidance Document (TGD) on risk assessment (EC, 2003). This document assigned criteria to identify substances of concern as PBT or very persistent and very bioaccumulative (vPvB) based on their half-lives in selected environmental media, their bioaccumulation in biota and their long-term ecotoxicity. This hazard based approach to chemical management was argued on the basis that ‘safe’ environmental concentrations for such substances cannot be established with sufficient reliability due to the unacceptably high level of uncertainty associated with quantitative risk assessment, the concerns that accumulation of such substances would be practically difficult to reverse, and the need to protect pristine (marine) environments. These concerns were then reflected in the EU REACH legislation which effectively removed risk assessment as the regulatory decision making tool for substances classified as PBT or vPvB.

Building upon a previous ECETOC report to develop a framework for the risk assessment of PBT chemicals (ECETOC, 2005a), this report reviews the scientific developments that have been made and details the on-going research that is being carried with the specific aim of reducing the uncertainty of risk assessments of PBT/vPvB chemicals.

Several case studies have been analysed and the literature on newly developed methodologies has been reviewed and the task force has concluded that the use of refined methodologies, which include the use of appropriate and/or improved test procedures, is strongly dependent on the nature of the respective chemical and its exposure characteristics. Therefore the choice of methodologies needs to be made on a case by case basis.


Due to the argued inadequacies of current risk assessment methodologies, several regulations (e.g. POPs, REACH authorisation) either do not allow or limit possibilities to conduct risk assessments as a basis for risk management decisions. Instead, decisions are based on a strict interpretation of the precautionary principle leading to hazard (rather than risk) based restrictions.

A scoping meeting was convened by ECETOC on April 22, 2008 that identified the subject of this proposed task force as one where an ECETOC task force could explore opportunities to progress the science in this area.

Terms of Reference

  1. Address ongoing research including:
    • decreasing trends of environmental concentrations of PBTs (reversibility);
    • current LRI projects in this area;
    • outcomes of the recent SETAC Pellston workshop and the proposed benchmarking tool that addresses recovery time versus emissions.
  2. Address issues of data availability and data quality e.g. with regard to reliable data on total emissions.
  3. If possible, recommend a scheme of approaches for risk assessments of PBT/vPvB or POP substances (see ECETOC TR No. 98 Risk Assessment of PBT Chemicals).
  4. Identify need for further Research in this area.
  5. The results of the task force activities should be reported in form of a peer- reviewed paper in a high impact journal in order to reach a wider audience.