Another branch of epidemiology pertinent to health risk assessment (RA) is pharmacoepidemiology, which applies epidemiologic methods to study the use, efficacy, and safety of pharmaceuticals. An overview of this branch of epidemiology has been given by Dr. Boji Huang as one of the Supercourse lectures. Like pharmaceutical toxicology, although pharmacoepidemiology has not flourished until the 1980s, its history goes back to the 1920s when salvarsan was used to treat syphilis in soldiers returning from World War I.

A timeline of notable drug disasters and important adverse drug effects has been given by D’Arcy (1993), who noted that the antimicrobial sulfa drugs (sulfanilamides) disaster in the 1930s shocked the people in the United States and prompted the passage of the Food, Drug, and Cosmetic Act of 1938. The thalidomide tragedy in the 1960s perhaps drew the greatest public attention. In the 1990s, there were disasters or important adverse effects related to the use of Terolidine, Propofol (not used in the United States), and varicella vaccines.

The regulation of drugs and medicines, and hence the RA involved as well, is quite different from those of pesticides, food, and other environmental or industrial contaminants. This is because both the therapeutic and side effects from drugs and medicines are more tangible, direct, and individual, than those from industrial or environmental contaminants. It is primarily due to these differences that pharmacoepidemiology has added a new twist to the regular course of RA. That is, comparatively speaking, more human toxicity data are used in this type of RA than in those concerning environmental contaminants.