The Role Of Population Modeling In Ecological Risk Assessment



RIFM is sponsoring a workshop organized by Roskilde University in Roskilde, Denmark, August 23-25, 2009.  The workshop is an outgrowth of the successful sediment program, sponsored by RIFM, that during the last three years has contributed substantially to our understanding of the fate and effects of fragrance materials in freshwater and estuarine sediments. An important aim of the sediment work was to explore the extent to which effects of fragrance materials on individual-level endpoints (such as growth, reproduction and survival) are likely to translate into ecologically relevant effects at the population level. Our work has shown that reproduction is generally the most sensitive individual-level endpoint, and that impacts of fragrance materials on reproduction seem to markedly overestimate risks for population dynamics. For none of the studies have we observed impacts on population dynamics at concentrations of fragrance materials likely to be found in the field. We believe that the application of population modeling can add value to ecological risk assessment in several ways by

  1. Reducing uncertainty in the extrapolation of standard test results to ecologically relevant impacts;
  2. Identifying high-risk scenarios for which testing efforts can be prioritized;
  3. Providing the kind of outputs that are essential for choosing among management alternatives and for facilitating cost-benefit assessments;
  4. Reducing the use of animal testing in a more ecologically sound manner than relying on in vitro or QSAR methods.

Whereas population modeling has been used extensively in conservation biology and other types of ecological management, its use in chemical risk assessment has been minimal. However, both industry and regulators are showing increasing interest in exploring the potential of such models in a risk assessment context. Initial efforts have been made to bring together stakeholders involved in pesticide risk assessment (with emphasis on the EU regulatory process) to identify the key barriers and actions needed for enhancing the role of population models in risk assessment.

There are additional reasons to believe that the timing is right for a new initiative to integrate population modeling into ecological risk assessment. First, though REACH will provide many challenges for industry, it also provides the opportunity to define approaches to address higher-tier risk assessments. Second, for highly important chemicals that fail the standard risk assessment thresholds, cost-benefit analyses (CBA) will be needed. Whereas the very rough measures of risk provided by PEC/PNEC ratios are insufficient as input to CBA, population models can be developed that provide exactly the kind of information needed for socioeconomic analyses. Third, the USEPA is currently rethinking its Ecological Risk Assessment Paradigm, which could provide opportunities for improving the way in which risk assessments are approached.

Aims of this Workshop

The workshop aims  to consolidate  the understanding that has been achieved in this field and to move towards a more extensive, integrated multicenter research program that will further demonstrate the importance and value of population modeling in the development of relevant ecological risk assessment.

A peer-reviewed publication of the workshop proceedings is intended.

For more information visit this Roskilde University link,