Pharmaceuticals are polluting waterways on all five continents — doing so at potentially toxic concentrations in more than a quarter of 258 global rivers sampled in a new, multi-institutional study.
Sites with the most contamination were located in low- to middle-income countries in areas with poor waste management infrastructure and robust pharmaceutical manufacturing, according to the study, published in the Proceedings of the National Academy of Sciences (PNAS). Scientists found the highest cumulative concentrations — for the 61 pharmaceuticals surveyed — in sub-Saharan Africa, South Asia and South America.
“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,” project co-leader John Wilkinson, from the University of York, said 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,” he added.
For this study, a consortium of more than 120 collaborators from academia, government and industry worldwide collaborated as part of the University of York-led Global Monitoring of Pharmaceuticals Project.
The expansive research team obtained samples from 1,052 sites along 258 of the world’s rivers in 104 countries, representing the environmental impact of 471.4 million people, according to the study.
Among the rivers were many of the world’s most noteworthy waterways, such as the Amazon, the Mississippi, the Thames and the Mekong. Rivers that pass through the most populated cities on the planet were also included, as were those in areas of political instability, the authors said.
Not only did the scientists find strong correlations between the lower socioeconomic status of a country and higher levels of pharmaceutical pollution, but they also said they found greater concentrations in regions of higher median age.
Activities linked to the highest concentrations included dumping trash along river banks, insufficient wastewater infrastructure, pharmaceutical production and the discharge of septic tanks into rivers, the authors found.
The most frequently identified drugs — the antiepileptic drug carbamazepine, the anti-diabetic medicine metformin and caffeine — were detected at more than half the locations sampled, according to the study.
Levels of at least one pharmaceutical exceeded concentrations considered safe for aquatic organisms at 25.7 percent of the sampling sites, the authors found. Some such pharmaceuticals included beta-blocker propranolol, antihistamine loratadine and antimicrobial drugs sulfamethoxazole and ciprofloxacin, the research showed.
Other pharmaceuticals with high concentrations worldwide were paracetamol, the antihistamine fexofenadine, the anticonvulsant gabapentin and the antimicrobial drug metronidazole, according to the study.
Due to the widespread nature of such potentially toxic pharmaceutical concentrations in waterways across the world, the authors concluded that “pharmaceutical pollution poses a global threat to human health.”