ABSTRACT
Every model has its own strengths and limitations. In environmental toxicology, the fundamental model is the toxicity test. This chapter introduces the issues in building experimental models to investigate the effects of chemicals on ecological systems. Since the care and well-being of terrestrial vertebrates has been of great public concern, strict guidelines as to husbandry and the humane treatment of these organisms have been produced by various government agencies, notably the National Institutes of Health. Over the years, a variety of test methods have been standardized. Standard methods do have a disadvantage; the methods are generally designed to answer very specific questions that are commonly presented. Acute toxicity tests cover a relatively short period of an organism's life span. Besides the complexity of the biological system and the length of the test, there are more practical aspects to toxicity tests. In aquatic test systems the tests may be classified as static, static renewal, recirculating, or flow through.
