Assessing Impacts of Environmental Contaminants on Wildlife

The impact of a toxic xenobiotic, natural or anthropogenic, on wildlife is difficult to evaluate because factors that influence exposure and risk vary widely among natural systems. Then, when considering the confounding influences of chemical interactions and the presence of natural toxics and toxins, widely diverse studies are needed to assess impacts of contamination on wildlife. In brief, wildlife toxicology has been described as the integration of three principal strategies: (i) laboratory screening to predict which chemicals may be acutely toxic or cause more subtle effects, such as reproductive impairment, behavioural aberrations or developmental changes; (ii) controlled studies where subjects are confined to a simulated natural environment and (iii) studies of natural populations. This chapter presents an overview of wildlife toxicology and contaminant risk assessment as traditionally evaluated, but also includes discussion of recent concepts of immunotoxicology, endocrine disruption and the presence of pharmaceuticals in nature. The focus is on anthropogenic chemicals and avian wildlife with comparisons to other taxa as appropriate. Birds have served as primary models because they have diverse behaviours and habitat associations and can be effectively studied in captivity and nature. Keywords: ecological risk assessment; wildlife toxicology; ecotoxicology; acute toxicity; reproduction; immunotoxicology; endocrine disruption; regulatory considerations; ecological hazard; sources of exposure