Ecotoxicity, the subject of study of the field of ecotoxiology, refers to the potential for biological, chemical or physical stressors to affect ecosystems. Such stressors might occur in the natural environment at densities, concentrations or levels high enough to disrupt the natural biochemistry, physiology, behaviour and interactions of the living organisms that comprise the ecosystem. (Source: R. Truhaut, Eco-Toxicology - Objectives, Principles and Perspectives in: Ecotoxicology and Environmental Safety Vol. 1(2) p 151-173) Quality of some substances or preparations which present or may present immediate or delayed risks for one or more sectors of the environment. (Source: GEMET/GRAHAW)