SPECIAL SECTION: Perspectives of the Scientific Community on the Status of Ecological Risk Assessment

Ecotoxicogenomics: bridging the gap between genes and populations

Ecotoxicogenomics might help solving open questions that cannot be answered by standard ecotoxicity tests currently used in environmental risk assessment. Changes in gene expression are claimed to serve potentially as early warning indicators for environmental effects and as sensitive and specific ecotoxicological end points. Ecotoxicogenomics focus on the lowest rather than the highest levels of biological organization. Our aim was to explore the links between gene expression responses and population level responses, both mechanistically (conceptual framework) and correlatively (Species Sensitivity Distribution). The effects of cadmium on aquatic species were compared for gene level responses (Lowest Observed Effect Concentrations) and individual level responses (median Lethal Concentrations, LC(50), and No Observed Effect Concentrations, NOEC). Responses in gene expression were on average four times above the NOEC and eleven times below the LC(50) values. Currently, use of gene expression changes as early warning indicators of environmental effects is not underpinned due to a lack of data. To confirm the sensitivity claimed by ecotoxicogenomics more testing at low concentrations is needed. From the conceptual framework, we conclude that for a mechanistic gene population link in risk management, research is required that includes at least one meaningful end point at each level of organization.

Problem formulation and hypothesis testing for environmental risk assessments of genetically modified crops

Environmental risk assessments can provide high confidence of minimal risk by testing theories, "risk hypotheses", that predict the likelihood of unacceptable harmful events. The creation of risk hypotheses and a plan to test them is called problem formulation. Effective problem formulation seeks to maximize the possibility of detecting effects that indicate potential risk; if such effects are not detected, minimal risk is indicated with high confidence. Two important implications are that artificial test conditions can increase confidence, whereas prescriptive data requirements can reduce confidence (increase uncertainty) if they constrain problem formulation. Poor problem formulation can increase environmental risk because it leads to the collection of superfluous data that may delay or prevent the introduction of environmentally beneficial products.

Ecological risk assessment of pollutant chemicals: extinction risk based on population-level effects

The extinction probability is one of the most useful endpoints that are utilized in conservation biology. A parallel approach is advocated for the ecological risk assessment of chemical pollutants. The presented framework estimates extinction probability induced by pollutant chemicals in order to evaluate ecological hazards of pollution, and is applicable to any biological community (aquatic or terrestrial). The analytical framework, which is based on stochastic population dynamics theory, is briefly explained. The extinction risk estimation is feasible if ecotoxicological data concerning pollutant effects on population growth rate of organisms (the intrinsic rate of natural increase), and if environmental exposure concentration is provided. Tentative risk estimation was made for some agrochemicals and surfactants on zooplankton populations (Daphnia) as target organisms.