ABSTRACT
Toxicity is the property or properties of a material that produces a harmful effect on a biological system. A toxicant is the material that produces this biological effect. Any chemical material can exhibit harmful effects when the amount introduced to an organism is high enough. Simple exposure to a chemical also does not mean that a harmful effect will result. The graph describing the response of an enzyme, organism, population, or biological community to a range of concentrations of a xenobiotic is the exposure-response curve. Toxicity is not generated by the unit mass of xenobiotic but by the molecule. Molar concentrations or dosages provide a more accurate assessment of the toxicity of a particular compound. It can be useful to plot biochemical activities, such as enzyme inhibition by a toxicant, as the response variable. In design of toxicity test there is often a compromise between the statistical power of the toxicity test and the practical considerations of personnel and logistics.
