Abiotic and biotic degradation are key removal processes that reduce the burden and impact of a chemical in the environment. Degradation data are also used to determine the environmental persistence of a chemical. However, for most chemicals the degradation data used in exposure and persistency assessment are limited in number; in many cases these data are restricted to a single value, or a default rate constant, based on the outcome of a simple screening assay. The wider environmental relevance of this rate of removal, including the impact of key environmental variables such as temperature, is therefore unknown and little or no certainty or confidence can be assigned to it. In order to improve confidence in environmental exposure and persistence assessments laboratory and model-based approaches are required that provide information about the range of removal rates that are likely to be observed in the environment together with an indication of the key parameters that may govern these rates. Phase 1 of this RFP seeks to review the state of the science associated with degradation and persistence assessment in the environment to identify testing strategies that will provide greater confidence in degradation half-lives. A second Phase of work may be commissioned to develop and validate the experimental and model-based approaches indentified within the review.
A detailed review of existing approaches for probabilistic degradation, persistence and exposure assessment. The review should include:
- Abiotic and biotic degradation
- Water, soil and sediment compartments
- Regulatory and non-regulatory experimental approaches and model-based approaches
- A critical evidence-based evaluation of the key factors that drive degradation rates in the each compartment.
- A recommended experimental framework that considers the practical implications, pros and cons, of these approaches to general chemicals and, considering scientific knowledge, for considering variable degradation rates in general chemicals regulation.
Download here the full version of the RfP LRI-ECO31.