Desk based review of current knowledge on pharmaceuticals in drinking water and estimation of potential levels
There are about 3000 pharmaceuticals registered in the UK and approximately 5000 substances listed as human pharmaceuticals were sold over the counter in the UK in 2004. In addition to the consumption of drugs for health care, there is also significant consumption of illegal drugs due to both recreational consumption and drug addiction, and for enhancement of sporting performance.
The Drinking Water Inspectorate commissioned us to identify all relevant, robust studies that investigate pharmaceutical concentrations in raw or treated water, or factors affecting those concentrations.
Worst-case modelling showed that even in a scenario with the highest estimated concentrations, the exposure ratios (comparison of the minimum therapeutic dose to the estimated intake from drinking water) for most of the major used pharmaceuticals and illegal drugs were significantly greater than 1000 and provided a high safety margin. Only 10 substances produced exposure ratios less than 1000 and four of these were illegal drugs. In only one case was the exposure ratio less than 100 and this was a special case, using a combined total for all Non-Steroidal Ant-Inflammatory Drugs at the lowest minimum therapeutic dose.
It therefore appears that even in this worst case situation there is no significant risk from pharmaceuticals discharged to drinking water sources.