Drugs on tap as the nights draw in

The concentrations of pharmaceuticals turning up in sewage plants and drinking water increase as the weather gets colder, report researchers in Finland.

Leif Kronberg and colleagues at Tampere University of Technology measured levels of five pharmaceuticals, first in sewage effluent, then downstream in a river, and finally in drinking water.

The sewage treatment plant they analysed removed significantly smaller amounts of the drugs in winter than in summer, increasing the risk of drinking water contamination in winter. Ibuprofen in particular was detected in a drinking water plant on the river Aura at about 8ng per litre in winter, but was virtually undetectable in summer.

Colder temperatures in snow- and ice-bound Finland slow down biological processes and the breakdown of pharmaceuticals. In summer, photodegradation speeds things up again.

But although more drugs tend to be taken in winter, this doesn’t explain higher levels in the water, Kronberg told Chemistry World. ’We found higher levels of pharmaceuticals in the water entering the treatment plant in May than in March, but the effluent water (the treated water) contained higher levels of the compounds in March,’ he said.

Kronberg said there is a worldwide problem with pharmaceuticals in water and sewage. ’What is not clear is the fate of pharmaceuticals in the environment and the impact on the ecosystem of these highly active compounds, and their degradation products and metabolites,’ he said. ’It looks like there could be an accumulation of the compounds in water and sediment during the cold seasons,’ he warned. Katharine Sanderson