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Introduction
Some Distinct Aspects of Exposure
Toxicant Effects
Molecular and Biochemical Effects
Gene Expression and Ecotoxicogenomics
Cellular, Tissue, and Organ Effects
Cells
Histopathology
Target Organs
Organismal Effects
Population
Community
Ecosystem to Biosphere
Approaches
Toxicity Tests
Biomarkers
Population
Community and Ecosystem
Landscape to Biosphere
Ecological Risk Assessment
Interconnections Between Ecosystem Integrity and Human Health
Acknowledgment
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Ecotoxicology is the science of contaminants in the biosphere and their effects on constituents of the biosphere (Newman, 2010). It follows from this definition that ecotoxicologists examine large-scale ecological phenomenon (Preston, 2002) in addition to those normally addressed in toxicology: ecotoxicology has an overarching goal of explaining and predicting effect or exposure phenomena at several levels of biological organization (Fig. 30-1). Essential explanations and models include those applied in conventional toxicology and a range of environmental sciences.
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Although Truhaut’s original definition of this new science encompassed effects to humans (Truhaut, 1977), most recent definitions of ecotoxicology do not. Relevant effects to nonhuman targets range from biomolecular to global. Taking on the classic toxicology vantage initially, suborganismal and organismal effects were emphasized during ecotoxicology’s nascent stage; however, studies of higher level effects and interactions are becoming increasingly commonplace as the science matures. Such indirect effects1 were initially considered problematic and reluctantly relegated to secondary importance (Fleeger et al., 2003) relative to direct effects to individuals. Indirect effects are now known to be as important as direct effects to nonhuman targets (Fleeger et al., 2003; Chapman, 2004). As the need to predict major effects to populations, communities, ecosystems, and other higher level entities has become increasingly apparent, more cause–effect models relevant to these higher levels of biological organization are added to the conventional set of toxicology models applied by pioneering ecotoxicologists.
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Contaminant chemical form, phase association, and movement among components of the biosphere are also central issues in ecotoxicology because they determine exposure, bioavailability, and realized dose. The context of these biogeochemical studies has expanded in the last several decades to encompass issues of larger scale such as global movement of persistent organic pollutants (POPs) (Wania and ...