Pharmaceutical drugs are chemicals used for the alteration, diagnosis, prevention and treatment of disease, health conditions or structure/function of the human body.
[2] PhACs have not (until relatively recently) been seen as potentially toxic because regulations associated with pharmaceuticals are typically overseen by human health organizations which have limited experience with environmental issues.
[3] Nearly all categories of pharmaceuticals including pain killers (analgesics and anti-inflammatory), antibiotics (antibacterial), anticonvulsant drugs, beta blockers, blood lipid regulators, X-ray contrast media, cytostatic drugs (chemotherapy), oral contraceptives, and veterinary pharmaceuticals among many others have been found in the environment.
Indirect sources are PhACs that have performed their biologically intended effect and are passed onto the environment in either their complete or a modified state.
One common indirect source of PhACs into the environment is the passing of antibiotics, anesthetics[2] and growth promoting hormones [5] by domesticated animals in urine and manure.
This is often stored in large pits before being pumped and applied to fields as fertilizers where many of the PhACs can be washed away by rainfall to aquatic environments.
Because rivers and streams are ever flowing objects they are an ideal pathway for antibiotics to reach bacteria and therefore provide a source and reservoir for resistant strains to develop and establish themselves.
Endocrine disruptors can replace or disturb the balance of hormones within an organism and have been found to be occurring in waters with a concentration in the ng/L level for certain compounds.