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Drugs in wastewater: treatment plants are not eliminating them completely

Water treatment plants are not fully removing drugs from wastewater. Yet another reason to avoid the overconsumption of drugs and to return unused medications to the pharmacy for incineration.

Pharmaceutical substances used in human and veterinary medicine find their way back into the environment after consumption. Eliminated from the body in urine and faeces, they are present in wastewater either in their initial active form, or as a derivative, active or not.

Sometimes unused medicines also end up in the water system if they are flushed down the toilet instead of being returned to the pharmacy.

Treatment plants are not fully removing all drugs from wastewater. Their effectiveness varies depending on the processes used, and remains low for some substances. A number of studies in France and elsewhere have revealed evidence of drug residues in wastewater, treated water and even in drinking water.

The extent of the environmental and health hazard related to the presence of micropollutants in water, including drugs, is still not known. Effects of this micropollution have been observed in some fish species, particularly sex changes in male fish. To date, there is no proven effect on humans.

The presence of drugs in wastewater and their persistence after treatment are all the more reason for us to make an effort to reduce drug waste, especially by avoiding overconsumption and encouraging people to return unused medicines to their local pharmacy, without waiting for these known risks to be confirmed.

©Prescrire 1 February 2013

"Drugs in wastewater: incomplete removal by treatment plants" Prescrire Int 2013; 22 (135): 52-54. (Pdf, subscribers only).

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