About 2 000 active pharmaceutical ingredients (APIs) are being administered worldwide in prescription medicines, non-prescription drugs and veterinary drugs, the residues of which are of increasing environmental concern as the number and density of humans and livestock requiring healthcare escalates.
Active pharmaceutical ingredients are found in surface waters, groundwater, drinking water, soil, manure, biota, sediment and the food chain. Although the contribution of each emission source varies across regions and types, the dominant sources of pharmaceuticals in the environment stem from untreated household wastewater and effluent from municipal wastewater treatment plants. Emissions from manufacturing plants and intensive agriculture and aquaculture can be important pollution hotspots locally.
Because pharmaceuticals are intentionally designed to interact with living organisms at low doses, even low concentrations in the environment can have unintended, negative impacts on freshwater ecosystems. For example, active substances in oral contraceptives have caused the feminisation of fish and amphibians; psychiatric drugs, such as fluoxetine, alter fish behaviour making them less risk-averse and vulnerable to predators; and the over-use and discharge of antibiotics to water bodies exacerbates the problem of antimicrobial resistance – declared by the World Health Organisation as an urgent, global health crisis that is projected to cause more deaths globally than cancer by 2050.