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Pharmaceuticals in drinking-water

This WHO technical report focuses on reviewing the risks to human health associated with exposure to trace concentrations of pharmaceuticals in drinking-water. 

Pharmaceuticals are synthetic or natural chemicals that can be found in prescription medicines, over-the-counter therapeutic drugs and veterinary drugs. Pharmaceuticals contain active ingredients that have been designed to have pharmacological effects and confer significant benefits to society. Traces of pharmaceuticals, typically at levels in the nanograms to low micrograms per litre range, have been reported in the water cycle, including surface waters, wastewater, groundwater and, to a lesser extent, drinking-water. The increase in detection of pharmaceuticals in the environment and the water cycle at trace levels is largely attributable to the advances in analytical techniques and instrumentation. Many surveys and studies have confirmed the presence of pharmaceuticals in municipal wastewater and effluents, and these have been identified as a major source of pharmaceuticals in drinking-water.

This report reviews human health risk assessments of pharmaceuticals in drinking-water conducted in the United Kingdom, Australia and the United States of America (USA). The approaches of acceptable daily intake (ADI) or minimum therapeutic dose (MTD) were adopted as the point of departure (PoD) in these studies to assess potential risks to human health through exposure to pharmaceuticals in drinking-water. Analysis of the results indicated that appreciable adverse health impacts to humans are very unlikely from exposure to the trace concentrations of pharmaceuticals that could potentially be found in drinking-water.

This report also asseses treatment technologies for removal of pharmaceuticals from drinking-water and emphasizes the need for preventive measures, such as take-back programmes, regulations, public guidance and consumer education to encourage the proper disposal of unwanted pharmaceuticals and minimize the introduction of pharmaceuticals into the environment. 

Although current published risk assessments indicate that trace concentrations of pharmaceuticals in drinking-water are very unlikely to pose risks to human health, knowledge gaps — notably due to limited occurrence data — exist in terms of assessing risks associated with long-term exposure to low concentrations of pharmaceuticals and the combined effects of mixtures of pharmaceuticals.