Over the past years several projects have focussed on exposure assessment of POPs/PBTs and have considerably improved the tools and knowledge. In particular modeling tools have been developed and improved and are now in the phase that they can be used reliably for certain classes of compounds, in particular narcotic chemicals. In parallel to human biomonitoring there is also an urgent need to improve the possibilities to interprete measured environmental exposure data in a toxicological context.
For POPs/PBTs a promising development is the use of CBB: critical body concentrations or critical body residues, in particular for chronic effects. This approach has two distinct advantages. Firstly it significantly improves the uncertainty of the effect assessment, as compared to using'classical' toxicity data. Secondly, exposure data on POPs/PBTs often come from (bio-)monitoring, for example as mg/kg body weight measurements, and CBB's directly provide a context for interpretatioon of such data. There are CBB data available, but these are not readily available nor properly validated and they are limited and in most cases restricted to acute toxicity.
The proposed project aims to collect available data, to validate them and to add data, preferably in a group approach for narcotics (or other MOA's) so that the number of data can be significantly enlarged.
”¢ To collect available LBB/CBB data (starting from the LETR database (Jarvinen and Ankley, 1999), to screen literature for additional data and to make data available in a user-friendly CBB-database
”¢ To develop a validation system for LBB/CBB data and apply these to the database
”¢ To design and execute a testing programme to validate the CBB toxicity range for narcotics (2-8 mmol/kg).
Several puplications have indicated that the CBB of narcotic chemicals is in the range of 2-8 mmol/kg. In practice this is sometimes used but still debated. The current project should generate sufficient confidence to generate sufficient acceptance to allow broad use.
CBB data can directly be used in risk assessments of PBTs and in interpreting monitoring data, especially data form biota and predators high in the food chain. It may also support the feasability of a'risk approach' for PBT/POPs.