ABSTRACT
Certain pharmaceuticals represent time markers of environmental releases based on the dates that each chemical compound was in use. This simple concept can be a powerful forensic tool when accurate usage history and sensitive analytical methods are available for a compound. Contrast agents for magnetic resonance and x-ray imaging are designed to be highly water soluble and nonreactive so that they pass easily through the human body. These properties make them persistent in the environment, and raise their potential as relatively conservative tracers of anthropogenic releases to the environment. Fluoroquinolone antibiotics are less conservative than contrast agents in terms of their environmental fate and transport, but are more commonly prescribed than contrast agents and are therefore potentially useful anthropogenic tracers across wider geographic areas. With a growing database of usage and occurrence, pharmaceuticals will soon become part of the suite of passive tracers of the environmental footprint of human activities. There are uncertainties with all of these tracers, but together they can help reconstruct the magnitude and timing of anthropogenic releases.
