The pharmaceutical products we use to stay healthy and treat disease can often end up in the environment through sewage or landfill runoff, and researchers are working to uncover the extent of this contamination through various environmental monitoring efforts. Getting the full picture of pharmaceutical pollution worldwide requires extensive international collaboration in order to sample areas with varying geographies and diverse populations, including remote areas where these tests have never been conducted before. A recently published study, the product of 127 collaborators from 86 institutions, spanned 104 countries across all seven continents to provide a new comprehensive look at contamination from 61 pharmaceuticals in rivers worldwide.
The Global Monitoring of Pharmaceuticals Project involved testing of 1052 water samples from 258 rivers across the globe, including in 36 countries where pharmaceuticals in surface water had never been studied before. Sampling locations included notable rivers like the Amazon, Mississippi, Thames and Mekong rivers, highly-populated cities like Delhi, London, New York, Lagos, Las Vegas and Guangzhou, remote villages such as the Yanomami Village in Venezuela, and even King George Island off the coast of Antarctica. The study also included a wide range of climates, from the high-altitude alpine tundra in Colorado to the Tunisian deserts, as well as areas of political instability like Baghdad, the Palestinian West Bank and Yaoundé in Cameroon.
To enable rapid global water sample collection, the researchers developed and shipped novel handheld collection kits that could be used to collect up to 24 4 mL samples per kit. Sample testing was performed via high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) at a central laboratory at the University of York. HPLC-MS/MS was used to ensure sensitive, high-throughput analysis covering all 61 pharmaceuticals of interest for each small sample, and all testing was performed at the same lab using the same method to limit variability, according to the project website.
The results of the study showed that pharmaceutical pollution was present in rivers on all seven continents, and about a quarter of the sites tested contained pharmaceutical contaminants at potentially harmful concentrations. The pharmaceuticals found at potentially harmful concentrations included the beta-blocker propranolol, the antibiotic sulfamethoxazole, the antibiotic ciprofloxacin and the antihistamine loratadine. Additionally, the team found strong correlations between a country’s socioeconomic status and its levels of pharmaceutical pollution, with lower-middle income nations having the highest levels of pollution. High pollution levels were most positively associated with regions of high median age, as well as those with high local unemployment and poverty rates. Factors most associated with high levels of pollution included rubbish dumping along river banks, dumping of contents of residual septic tanks into rivers, and inadequate wastewater infrastructure and pharmaceutical manufacturing. Notably, areas where pharmaceutical pollution has been researched the least, such as sub-Saharan Africa, South America and parts of South Asia, were found to have the highest levels of pharmaceutical pollution. This study was published in the Proceedings of the National Academy of Science (PNAS).
“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. 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 the data focused on a select few areas in North America, Western Europe and China,” said project co-leader John Wilkinson, of the Department of Environment and Geography at the University of York. “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.”
The researchers say their approach could be expanded in the future to include testing of other environmental samples such as sediments, soils and biota, and could lead to the development of more extensive global-scale datasets on pharmaceutical pollution.
Photo: Riverside in Luang Prabang, Laos, one of the areas monitored in the study. Credit: John Wilkinson