Pharmaceuticals in the environment: expected and unexpected effects on aquatic fauna.

A growing database reports that human and veterinary pharmaceutical residues are present in aquatic and terrestrial environments worldwide. Evidence indicates that nontarget organisms may be chronically exposed to low (ng/L to μg/L range) concentrations of a variety of pharmaceuticals, but that even these concentrations may result in significant biological effects. Here are briefly summarized well-documented examples demonstrating how pharmaceuticals behave differently from conventional pollutants, which suggests that they must be considered when risk to ecosystems and human health is assessed. In particular, examples are presented of expected effects related to the therapeutic mode of action, unwanted/side effects mainly related to oxidative stress, and unexpected effects induced by environmental concentrations of pharmaceuticals in aquatic animals. A list of the most relevant reviews on the subject is also provided to provide a more complete perspective on the effects of environmental pharmaceuticals in nontarget species.