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Pharmaceutical residues in the water

Too many medicines are now being found in surface and ground water.

Thousands of tonnes of human and veterinary medicines are used every year worldwide. After consumption, pharmaceuticals are eliminated mainly through the faeces or urine, sometimes in an active form. They enter the surface and ground water, generally via water purification plants which are unable to eliminate all drugs. Furthermore, if unused medicines are not incinerated, they can also end up polluting surface and ground water.

Very low concentrations of numerous pharmaceutical substances are found in the outflows from water purification plants, in surface and ground water and in some samples of drinking water.

This ongoing pollution can have biological consequences for certain aquatic species. The effects on humans are unknown.

The treatments carried out in drinking water purification plants can now eliminate drugs from the water. But there are still uncertainties as to whether chlorine- or ozone-treated substances continue to be biologically active. Treatment may also be insufficient due to inaccurate procedures.

It would be better to take preventive measures without waiting for the results of environmental and health risk evaluations. That means that individuals should avoid throwing medicines into the dustbin or down the toilet, but instead return them to the pharmacy for incineration.

©Prescrire June 2007

Source: "La pollution des eaux par les médicaments" Rev Prescrire 2007 ; 27 (284) : 460-464.

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