Considerations of Amphibian Models and Testing Paradigms for Ecological Risk Assessment

Abstract

Amphibians are unique among vertebrates in their physiological and life-history adaptations. Amphibians are particularly challenging given their multi-phasic existence that enables some species to exist in aquatic and terrestrial habitats. With increasing human encroachments, amphibians face multiple stressors, including habitat destruction, climate change and pollution. The use of amphibians in toxicity testing protocols to enable environmental risk assessment applications has served to help make management decisions regarding hazardous substances released into the environment. Toxicity testing protocols that use larval amphibians are predominantly exposed through test compounds administered to the water. However, for terrestrial forms (e.g., frogs, toads and salamanders), examples are provided where test compounds were mixed into soil and sediments. Oral exposure routes for adult amphibians are complicated by practical considerations in exposing prey and inadvertent soil ingestion. In this chapter, we discuss the available science in controlled testing protocols and their potential risk assessment applications while recognizing some of the advantages, disadvantages and uncertainties.