TR 098 – Risk Assessment of PBT Chemicals


TR 098 : Risk Assessment of PBT Chemicals | December 2005

Many chemical regulatory schemes exist around the world that contain hazard-based criteria to identify and prioritise persistent, bioaccumulative and toxic (PBT), or very persistent very bioaccumulative (vPvB) chemicals. These are chemicals that have the potential to persist in the environment, accumulate within the tissue of living organisms and, in the case of chemicals categorised as PBTs, show adverse effects following long-term exposure.

Concerns have been expressed within various European Commission documents that risk assessment cannot be applied to chemicals categorised as PBTs or vPvBs due, in part, to the uncertainties involved with current methodologies. These documents argue that decisions on chemical management should be based on the hazard, rather than the risk, of these chemicals. The aim of this report is to investigate whether these concerns over the application of risk assessment to chemicals categorised as PBTs or vPvBs are valid and to identify ways in which the risk assessment process can be improved in order to reduce the uncertainties involved.

The report includes an overview of a number of relevant regulatory schemes and an introduction into the principles of risk assessment and the application to chemicals categorised as PBTs and vPvBs. It also contains sections aimed at identifying the main issues and sources of uncertainty within exposure, bioaccumulation and effects assessments. Recommendations are then made so that a refined, and less uncertain, risk assessment can be produced. This refined risk assessment is considered appropriate for assessing the environmental safety of chemicals identified as being of concern due to their persistent, bioaccumulative and toxic profile.

Risk assessment is a continually developing science and the report concludes with opinions on how this science can be advanced further in order to generate assessments of environmental risk that are even more predictive of the real world.

This Task Force recognises that chemicals policies across the world have been proposed, in part, to more rapidly screen and regulate chemicals to better protect the environment and human health. It has been noted that the existing risk assessment process in Europe is too time consuming and, for chemicals of high concern, too much uncertainty exists in addressing the potential risks posed by these chemicals. The Task Force acknowledges and agrees with these opinions and supports approaches for more rapid, risk-based assessments of chemicals that pose low to medium risks to the environment and human health. These processes, when properly designed and implemented, will result in more rapid and less uncertain assessment of risks posed by chemicals. For those chemicals of higher concern, i.e. chemicals categorised as PBTs and vPvBs, the processes and procedures set forth in this report, will result in more rapid assessments (by the use of exposure modelling and commencing effects assessment at a higher tier). They will also reduce uncertainty through more robust, albeit longer, studies of environmental effects through the food chain. However, the Task Force believes that the proposals within this report when combined with a well-designed chemicals policy will result in a more expeditious assessment of the risks posed by the majority of organic chemicals.