Toxicity is the inherent potential of a substance, chemical, or biological agent to induce adverse effects in an organism. This concept is central to toxicology, which studies the adverse effects of chemical, physical, or biological agents. The degree of toxicity is not solely determined by the substance itself, but critically depends on the dose administered, the duration of exposure, the route of entry, and the susceptibility of the organism. At a foundational level, toxicology operates under the principle that "the dose makes the poison," meaning that nearly any substance can be toxic depending on the concentration and amount of exposure. Toxic mechanisms can involve disrupting fundamental cellular processes, such as oxidative stress, interfering with metabolic enzyme pathways, or causing direct membrane damage.