PRINCIPLES OF ENVIRONMENTAL TOXICOLOGY AND CONTAMINATION (PART III)

Table of Contents

1. Index
2. UNIT 9 - Environmental risk assessment
   1. Introduction
   2. Problem formulation
   3. Analysis Phase
   4. Risk characterization
   5. Risk management and assessment
   6. Human health risk assessment
3. UNIT 10 - Environmental risk communication
4. UNIT 11 - Modelling in Ecotoxicology
5. UNIT 12 - Legislation
6. Glossary of key terms associated with environmental toxicology

Analysis Phase

This phase of the ecological risk assessment includes the evaluation of exposure to stressors (e.g. the exposure level or concentration of the stressor of concern) and the relationship between the stressor characteristics and ecological effects. Therefore, this step includes two principal activities:

• Characterization of exposure - relevant and credible data are analyzed to describe the source(s) of stressors, the distribution of stressors in the environment, and the contact or co-occurrence of stressors with ecological receptors. An exposure profile is developed (fig. 1) that identifies receptors and exposure pathways, describes the intensity and spatial and temporal extent of exposure as well as the impact of variability and uncertainty on exposure estimates, and presents a conclusion about the likelihood that exposure will occur.

• Characterization of ecological effects - important data (e.g. obtained from bioassays) are analyzed to evaluate stressor-response relationships and/or to provide evidence that exposure to a stressor causes an observed response. The characterization describes the effects (e.g. bioaccumulation effects, changes in food availability or other changes in populations and communities of organisms) that are elicited by a stressor, links these effects with the assessment endpoints, and evaluates how the effects change with varying stressor levels. The conclusions of the ecological effect(s) characterization are summarized in a stressor-response profile (evaluates whatever is appropriate for the defined assessment endpoints e.g. single species, populations, communities, ecosystems) (fig. 1). Thus, this profile summarizes the nature and intensity of effect(s), the timescale for recovery (where appropriate), causal information linking the stressor with observed effects, and uncertainties associated with the analysis.