National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
In Europe, several different regulatory frameworks exist which deal with specific groups of chemicals (e.g. industrial chemicals, biocides, pesticides, pharmaceuticals), or which serve a particular purpose (e.g. protection of the marine environment). Several of these regulatory frameworks have their own criteria for dealing with Persistent, Bioaccumulative, and Toxic (PBT) substances or Persistent Organic Pollutants (POP). This study focused on criteria for persistence of substances. Criteria from different regulatory frameworks were compared. It appears that for persistence, differences in criteria are relatively small. Some frameworks do not use their own criteria but refer to criteria from REACH or the TGD used in the former new and existing substances legislation. Despite these small differences in criteria among the regulatory frameworks, details in the assessment procedure could cause the final assessment of persistence to deviate substantially among the frameworks. Even when the criteria are the same, the way the information from experimental studies is used may vary greatly. For example, the half-life of a substance could refer to degradation only, or it could be a half-life for dissipation. In this respect, it is also important how the results from field studies are considered in the assessment. Another aspect is the temperature for which the criteria are defined (ambient or room temperature), and if a temperature correction should be applied. Differences can also be caused by the way in which bound residues are regarded, with the extreme cases of bound residues being completely disappeared versus completely persistent. Further, how to deal with photolysis and hydrolysis is often not well defined. These are just some examples of aspects that are treated differently in the different regulatory frameworks. For further harmonisation of the persistence assessment between different regulatory frameworks, it is therefore necessary to harmonise not only the criteria on which the persistence assessment is based, but also the guidance documents on the interpretation of the data.