Twenty-nine different pharmaceutical drugs — including antibiotics, antidepressants, antihistamines and medication for the treatment of diabetes and epilepsy, to name just a few — have been found in two rivers near York, in concentrations higher than some levels previously discovered throughout Europe and Asia.

Conducting some of the most detailed research of its kind, a team from the University of York took samples from several different locations on both the Foss and Ouse rivers over the course of a year. During that time, researchers discovered:

• Some drug concentrations were higher than found in other parts of Europe and Asia.
• Some medications experienced seasonal spikes, for instance, antihistamines were found in greater concentrations during the summer months while medications to treat cold and flu symptoms were found in greater concentrations during the winter months.
• Concentrations of drugs not generally available in the U.K. were also discovered and were thought to be discharged into the city’s waters after ingested by tourists from the U.S. and China.

According to Professor Alistair Boxall from the University of York's Environment Department: "There isn't any evidence for impact on human health from pharmaceuticals in rivers, but it definitely deserves more investigation."

"If you compare the levels found in the study with what a patient takes then the degree of exposure is very low. For example, we saw concentrations of metformin — a drug used to treat type 2 diabetes at around 500 nanograms per liter. If you drank two liters of this water, you would get about a millionth of a patient's daily dose of the drug."

Professor Boxall added: "However, it is important to realize that these drugs are being emitted continuously into the environment and that we will be exposed to them across our lifetime. There is, therefore, a concern that some may be causing harm."

"It is a really complex issue to tackle and we don't really have the methods to understand whether long-term exposure to low levels of pharmaceuticals matters or not."

Additionally, Professor Boxall is concerned about the impact on the ecosystem as previous studies have revealed that medications and other pharmaceuticals at these levels can impact the behavior and the reproduction of fish and invertebrates.

As such, a new initiative spearheaded by the University at York will analyze water samples taken from 60 different rivers from all over the world. The research team expects to have results from the analysis available by the end of the year.