Now a subject in its own right, Toxicology evolved over many decades from a specialized discipline within the broader scope of Pharmacology. Historically, Toxicology concerned poisons, substances that debilitated or killed people, including therapeutic agents taken in excess, as well as other chemicals employed to kill insects and other animals. Toxicology served Pathology in determining the cause and manner of death.
As modern Chemistry evolved, Toxicology took on a broader focus and assessed exposure to and the toxicity of materials and chemicals in the environment. Concern about alcohol and drugs as substances that could impair driving also increased during the past century. Forensic toxicology focused on the presence and amount of drugs in body fluids, including ranges of concentrations of drugs considered non-toxic. At the same time, pharmacologists became interested in drugs and their toxic effects on vulnerable organs, including the brain.
During the past fifty years, the disciplines of Pharmacology and Toxicology have overlapped considerably in subject matter.