Understanding the relationship between extraction technique and bioavailability
Environmental Sciences Manager Malyka Galay Burgos
Background
An ECETOC workshop "Significance of Bound Residues in Environmental Risk Assessment" was held on 14-15 October 2009 in Brussels. The conclusions (see ECETOC Workshop Report No. 17) state that "non-extractable residues are currently characterised by a pragmatic extraction approach by determining whether they are extractable or not. This extraction approach has been historically implemented with various solvents under varying conditions and not necessarily linked to the properties of the chemical, nor the matrix. There is a need to develop a standard framework for extraction methods and to associate the extractable fractions (leachable and NER ) with both a level of bioavailability (accessibility) and appropriate test organism(s) for the appropriate environmental compartment. It is recognised that the development of new methods to screen bioavailability of such fractions may be needed to validate this association. This exercise would support a consistent interpretation of the data and provide a transparent basis for assessing the potential risk of NER.
An ECETOC Task Force has been commissioned to develop a framework for intelligent extraction strategies.It is foreseen that the Task Force will complete its work by end 2011. A detailed work plan will be agreed at the first meeting that will be planned as soon as the Task Force has been set up.