Acute and Subacute Toxicology in Evaluation of Pesticide Hazard to Avian Wildlife: Appx P3 - The Revised Up-and-Down Procedure: A Test Method for Determining the Acute Oral Toxicity of Chemicals

Single-dose acute oral and short-term subacute dietary toxicity tests with captive birds provide critical information on the potential hazard of pesticides to wild populations. The two tests have similar experimental designs and both generate a lethality curve and estimation of its midpoint, the median lethal dosage (LD50) or concentration (LC50). Although LD50s and LC50s are widely used to characterize pesticide toxicity, the lethality curve and critical observation of animal response to chemical challenge provide necessary insight for hazard evaluation. The highly controlled acute test is based on graded dosage by body mass and provides a sound method of comparing naive sensitivity to toxicant and a means of detecting pesticides that may cause large-scale field kills. In contrast, the subacute test presents graded concentrations of a chemical in the diet for a specified duration, usually 5 days. This feeding trial provides an evaluation of response to repeated chemical exposures as may be encountered in the field. This chapter is an appraisal of the two basic tests of lethality with an emphasis on factors that may affect interpretation of potential hazard.