Time-Dependent Toxicity of Neonicotinoids and Other Toxicants:Implications for a New Approach to Risk Assessment

Abstract

A fundamental goal of toxicology is to determine safe levels of exposure to potentially poisonous substances for humans and the environment. Traditionally, safe levels have been estimated in laboratory toxicity bioassays by calculating the non-observable effect level (NOEL) of a chemical to a variety of organisms which are representative of certain taxa, i.e. mammals, birds, fish, crustaceans, algae, etc. There are, however, fundamental problems with the validity of this approach, both conceptual and statistical in nature, as indicated by Landis and Chapman and other authors. Thus, the outdated NOEL concept is being replaced by the no-effect concentration (NEC) level, which assumes that toxic chemicals do not have any effect on a population of organisms at very low concentrations.