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Modelling the effects of pesticides on non-target aquatic organisms to improve risk assessment - PS2304

Description
Ecological risk assessment for pesticides relies upon describing a range of processes and chemical properties to compare exposure and effects. The resulting descriptions can never fully encompass the system under consideration and a series of inaccuracies and approximations arise. Uncertainties are present in defining and describing exposure scenarios and in selecting test species on which to base the risk assessment. Exposure assessment has primarily focused on the fate of pesticides released into the environment and has largely ignored the ecological aspects of exposure, effects and recovery operating within the agricultural landscape. Exposure of the aquatic environment to pesticides varies greatly over time and standard laboratory toxicity tests provide only a crude measure of potential effects likely to result. There are significant uncertainties in describing the propagation of effects through different levels of biological organisation. Aquatic risk assessment primarily considers effects on individuals and, at higher tiers, populations of single species even though ecological protection aims related to biodiversity and ecosystem function operate at the community level.
The failure to address uncertainty and variability within current regulatory practice is widely acknowledged. Risk quotients have generally been calculated to incorporate worst-case assumptions and then regulated on the basis of safety or uncertainty factors. Nevertheless, it is difficult to justify this approach on scientific grounds, particularly as levels of uncertainty, and thus degree of protection, cannot be demonstrated. Effective regulation is hampered by the lack of realism in the approach and it is difficult to prioritise areas for concern and thus mitigation.

The aim of this project is to develop a higher-tier methodology for ecological risk assessment that is specific to aquatic organisms, operates at a number of scales, and which is able to incorporate uncertainty and variability in exposure and effects. The response of exposed aquatic ecosystems is a product of (i) exposure; (ii) sensitivity of the exposed aquatic communities; (iii) life history of exposed species; (iv) structure of the aquatic landscape; and (v) interactions between these components. Sources of uncertainty and variability will be separated and addressed for each component through algorithms to describe ecosystem responses. The validity of the resulting assessment methodology will be verified against existing semi-field and field biomonitoring data.

The methodology will have the following characteristics:
• Cohesive and achievable (the user will be able to produce a more robust risk assessment for aquatic organisms on the basis of output from this project alone);
• Flexible (it should be able to incorporate specialised modules, for example population modelling, depending on what is funded now or in the future);
• It will build on previous research funded by DEFRA and others;
• The methodology will fit within the current regulatory framework;
• Components may be either deterministic or probabilistic, depending upon the most appropriate and robust approach to incorporate particular aspects of uncertainty and variability;
• The project will focus primarily on the effects side of the risk equation;
• Exposure can be split into ‘fate’ and ‘ecological’ components; existing approaches (e.g. FOCUS) will be used for fate assessment, whereas significant effort will be put into incorporating ecology as the link between fate and effects;
• The project will output algorithms, data fields etc which will be coded outside of this project into the overall model framework/software;
• These algorithms will be verified/validated using results from semi-field experiments and field biomonitoring programmes.
Objective
The aim of the project is to develop a higher-tier methodology for ecological risk assessment that is specific to aquatic organisms, operates at a number of scales, and which is able to incorporate uncertainty and variability in exposure and effects.
The specific objectives are to:
1. Derive ‘reference images’ of the aquatic ecosystems to be protected and scenarios to encapsulate regional variation and underpin the aquatic module
2. Extend current knowledge on species sensitivity distributions and their ability to protect indigenous biodiversity with special reference to fungicides
3. Address uncertainties in extrapolating to the population level through the collation of life history information for characteristic freshwater species in the UK, including dispersal ability and recovery potential
4. Characterise spatial and temporal variation in the exposure profile, incorporating landscape ecology, effects of pulsed exposures and time-to-event analysis
5. Characterise uncertainties in extrapolating to the community level by considering the relative importance and predictability of indirect effects
6. Verify the theoretical base of the module and prepare case studies to exemplify and validate the module against field biomonitoring data
7. Communicate and collaborate with relevant research projects funded by DEFRA and other organisations
Project Documents
• Final Report : Modelling the effects of pesticides on non-target aquatic organisms to improve risk assessment   (2320k)
Time-Scale and Cost
From: 2003

To: 2006

Cost: £299,615
Contractor / Funded Organisations
University - York, University - Sheffield, University - Cranfield
Keywords
Chemicals              
Ecotoxicology              
Environmental Effects              
Environmental Protection              
Pesticide use              
Pesticides              
Pollution              
Water              
Fields of Study
Pesticide Safety