Geospatial approaches to increasing the ecological relevance of chemical risk assessments

Background

For several decades, the prospective risk assessment of chemicals across all regulatory jurisdictions has followed a generic approach of comparing estimated exposures to toxic thresholds designed to be protective of all species. This approach does not recognise geographic patterns of species distributions or acknowledge that particularly sensitive species may not occupy potentially exposed habitats. Therefore, risk assessments could be overly conservative and restrictive for some uses of chemicals. Geo-referenced ecological data are becoming increasingly available at spatial resolutions applicable to chemical risk assessment, potentially facilitating enhanced environmental relevance of such risk assessments. Environmental management practices can result in heavily modified ecosystems in terms of both physical characteristics and ecological assemblages. For example, intensively farmed land is managed for crop production and will therefore not support the diversity of species that could be sustained under certain other land uses. Consideration of the spatial patterns inherent to multi-use, multi-stressor landscapes raises important questions about how to assess cumulative effects of chemical stressors in the environment. Given that much of the environment is managed in various ways, greater realism in assessing potential additional stress due to chemical exposure could be achieved if this range of managed and unmanaged environmental typologies and their constituent biological communities were mapped and described. Making representative or even spatially explicit scenarios would enable similarly localised chemical exposures to be assessed with high environmental relevance.

A potential approach would be to describe a range of environmental scenarios representative of ecosystems contained within managed and unmanaged environments, accounting for the various ecosystem services provided by these different portions of the landscape. These scenarios might include occurrence of particular species or traits based on structural and functional diversity, management practices, as well as other biotic and abiotic descriptors. One ongoing initiative that could be included in scenario development is the EC mapping of ecosystem services in Europe (MAES project). This makes it possible to overlay geospatial maps of ecosystem services and biological assemblages with spatially explicit chemical exposures in order to assess potential impacts.