Despite growing evidence of deleterious effects on ecological or human health, little is known regarding the global occurrence of pharmaceuticals in rivers. Studies assessing their occurrence are available for 75 of 196 countries with most research conducted in North America and Western Europe leaving large geographical regions relatively unstudied. Here, we present the findings of the first global reconnaissance of pharmaceutical pollution in rivers. The study monitored 1052 sampling sites along 258 rivers in 104 countries of all continents thus representing the pharmaceutical fingerprint of 471.4 million people. We show the presence of these contaminants in surface water poses a threat to environmental and/or human health in more than a quarter of the studied locations globally.
Some of the key findings:
Of the 61 pharmaceuticals we monitored, 53 were detected in at least one sampling site. Of which, 4 were detected across all 7 continents.
Carbamazepine was the most frequently detected pharmaceutical worldwide. The drug was found in the water of 62% of sampling sites globally- that's 652 locations across all the continents except Antarctica.
Carbamazepine is a medicine used to treat epilepsy and nerve pain.
Image credit: Google Maps
The most polluted sampling site worldwide was located in the Rio Seke (La Paz, Bolivia) and had a cumulative pharmaceutical concentration of 297 µg/L. For comparison, that's a 115 times higher pharmaceutical concentration than in the East River of New York City.
...was the only country where none of the 61 monitored pharmaceuticals were detected.
Image credit: Halldór Pálmar Halldórsson
Caffeine, carbamazepine and metformin
Metformin (used to treat Type-2 diabetes), caffeine and carbamazepine (used to treat epilepsy and nerve pain) were detected in more than half of the studied sites worldwide. Caffeine was detected across all 7 continents.
A total of 34 pharmaceuticals were detected in the Kai Tak River in Hong Kong. This was more than in any other river we studied worldwide.
Image credit: John Wilkinson
The single highest concentration of any pharmaceutical detected in the study was 227 µg/L of paracetamol in Bolivia.
Although typically used to treat headaches, some in Nigeria use the medication to help tenderise meat and beans while cooking.
Concentrations of at least one pharmaceutical were above levels which may be toxic to algae, fish or daphnia at a quarter of monitored sites worldwide.
Half a billion
More than 471 million people live in the river catchments monitored in this study.
This one study presents data from more countries around the world than the entire scientific community was previously aware of: 36 new countries to be precise where only 75 had ever been studied before.