In vivo studies are essential in toxicology for several reasons: - Physiological Relevance: They provide data on the actual biological effects of a substance within a living organism, accounting for complex interactions among cells, tissues, and organs. - Pharmacokinetics: These studies help in understanding the absorption, distribution, metabolism, and excretion (ADME) of chemicals. - Dose-Response Relationships: They allow for the determination of dose-response relationships, which are crucial for risk assessment and establishing safe exposure levels. - Chronic and Acute Toxicity: In vivo studies can assess both short-term (acute) and long-term (chronic) toxic effects.