A wide-ranging study into pharmaceutical pollution of the world's rivers has found that more than a quarter of those analyzed carry potentially toxic levels of drugs. The research greatly expands our scope of knowledge around this type of pollution, and also teases out useful insights into where it is most heavily concentrated.
The research was led by scientists at the UK's University of York who identified some sizable gaps in what we know about the occurrence of pharmaceuticals in the world's river systems. Up until now research had only been available for 75 out of 196 countries, mostly centered on North America and Western Europe, meaning the situation for large parts of the world remained unknown.
"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 co-leader of the research project, Dr John Wilkinson. "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."
In what they call a global reconnaissance of pharmaceutical pollution in rivers, the authors assessed 1,052 sampling sites along 258 rivers in 104 countries from every continent on Earth, "representing the pharmaceutical fingerprint of 471.4 million people." This showed that pharmaceutical contamination in surface water is at high enough concentrations to pose a threat to the environment and/or human health in more than a quarter of the locations studied.
"Through our project, our knowledge of the global distribution of pharmaceuticals in the aquatic environment has now been considerably enhanced," said Wilkinson. "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."
The study shows that the highest levels of pharmaceutical pollution come from waste dumping along river banks, poor wastewater infrastructure, pharmaceutical manufacturing, and the dumping of septic tank contents into rivers. The contaminants detected most frequently were the anti-epileptic drug carbamazepine, caffeine and the diabetes drug metformin, along with the antibiotic sulfamethoxazole.
The scientists also found strong correlations between high levels of pollution and a lower socioeconomic status of a country, high poverty rates and high local unemployment. The most polluted countries were the ones studied the least so far, in sub-Saharan Africa, South America and southern Asia. Just two locations revealed no contamination at all, Iceland and the Yanomami Village in Venezuela, where the locals don't use modern medicine.
The study was part of a research effort called the Global Monitoring of Pharmaceuticals Project, and the scientists hope to continue broadening our knowledge in this area by expanding their approach to include analysis of things like sediments and soils.
The research was published in the journal Proceedings of the National Academy of Science.
Source: University of York