A massive investigation into the cleanliness of the world’s rivers has found potentially harmful levels of pharmaceutical contamination in more than a quarter of the locations studied. After analyzing samples from 258 different rivers in 104 countries, the study authors detected dangerously high concentrations of at least one compound at 25.7 percent of sampling sites.
Presenting their shocking findings in the Proceedings of the National Academy of Sciences, the researchers explain how they set out to conduct the first truly global study into pharmaceutical pollution, testing for 61 different medical contaminants on all seven continents. Traveling to some of the most remote regions of the planet, the team gathered data from 36 countries that had never previously been assessed.
Of the 61 pharmaceuticals under investigation, 53 were detected in at least one sampling site, with four of these being present on all continents – including Antarctica. On a global level, carbamazepine – which is used to treat epilepsy and nerve pain – was the most frequently detected compound, and was present at 62 percent of sample sites.
Caffeine and a diabetes drug called metformin were also present in more than half of the water samples.
“We’ve known for over two decades now that pharmaceuticals make their way into the aquatic environment where they may affect the biology of living organisms,” said study author Dr John Wilkinson in a statement.
“But one of the largest problems we have faced in tackling this issue is that we have not been very representative when monitoring these contaminants, with almost all of the data focused on a select few areas in North America, Western Europe and China.”
“Through our project, our knowledge of the global distribution of pharmaceuticals in the aquatic environment has now been considerably enhanced. 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.”
Conducted as part of the Global Monitoring of Pharmaceuticals Project, the study reveals that contamination tends to be higher in lower-income countries, and is largely driven by poor wastewater and waste management infrastructure, improper pharmaceutical manufacturing procedures, and the dumping of septic tank contents into rivers. Overall, the highest concentrations of contaminants were found in sub-saharan Africa, southern Asia, and South America, with the lowest levels of pharmaceutical pollution found in Oceania.
Iceland was the only country where none of the 61 compounds were detected, while three sampling sites in a remote region of Venezuela were also completely clear. Located in an area inhabited by the indigenous Yanomami tribe, the cleanliness of the water at this location reflects the fact that the locals don’t use industrial pharmaceuticals.
The highest average concentration of pollutants was found in Lahore, Pakistan, followed by La Paz in Bolivia and Addis Ababa in Ethiopia. La Paz was also home to the single most polluted sampling site, with a stretch of the Rio Seke containing 115 times more pharmaceutical contamination than New York’s East River.
As the researchers point out, the presence of pharmaceuticals in major waterways can interact with the biology of aquatic wildlife and human populations. High concentrations of antimicrobials can also exacerbate the global antimicrobial resistance crisis. The fact that a sampling site in Bangladesh contained more than 300 times the safe amount of an antibiotic drug called metronidazole is, therefore, a highly concerning finding.
Taken together, there’s no doubt that the data makes for pretty grim reading, although the study authors are hopeful that their efforts to highlight the extent of the problem may now lead to a coordinated global effort to reduce pharmaceutical contamination in the world’s rivers.