If the development and medication use have made it possible to improve our health and our life expectancy, their residues are eliminated and end up in wastewater and eventually, in part, in rivers. However, if the drugs are designed to have a precise action on the human being, their impacts are unpredictable on thes other living organisms (fish, crustaceans, microorganisms, flora, etc.). But there is no global study to assess the situation at the global level, which is why the University of York launched in 2018, with 86 other institutions including Inrae in France, a study to analyze the samples of 258 rivers in 104 countries on five continents.
The study included major rivers such as the Thames, the Amazon, the Mississippi, or the Mekong with sampling sites in regions where modern drugs are not used (such as a Yanomami village in Venezuela) and in some of the most populated cities on the planet like New York or Delhi. The analysis of the samples covered 61 of the most commonly used medicinal substances: antibiotics, analgesics, anti-inflammatories, antihistamines, antidiabetics, antidepressants, stimulants (such as caffeine). The rivers of 36 countries taken into account had never been monitored for pharmaceuticals before.
In question, a treatment of waste water and poorly developed waste
During the study, 1052 samples were collected across the globe according to the same protocol and the concentrations of medicinal substances were measured by the same laboratory to analyze the degree of contamination of the waterways. “The scale of the study allows a global vision of this contamination which is present in the streams analyzed from all continents, although variable in concentration and frequency. “, explains the Inrae on this subject. The results published in the scientific journal Proceedings of the National Academy of Sciences (PNAS) show that the degree pollution of waterways is correlated with the socio-economic conditions of the country.
Thus, the most contaminated sites being those in low-income countries and with little or no wastewater treatment domestic, or from the pharmaceutical industries. Some regions that had never been studied before (South America, Sub-Saharan Africa and parts of South Asia) are among the most affected by drug pollution, with cumulative concentrations particularly high. For example, researchers have found high drug substance concentrations in Pakistan (70.8 µg/L with a measured maximum of 189 µg/L) and Bolivia (68.9 µg/L with a measured maximum of 297 µg/L). L).
A beta-blocker, two antibiotics and an antihistamine at too high concentrations
The study also reveals that a quarter of the sites studied had a contaminant concentration potentially dangerous for the environment, in particular for two antibiotics (sulfamethoxazole and ciprofloxacin), an antihistamine (loratadine) and a drug used for hypertension (propranolol). Finally, it turns out more generally that the pharmaceutical pollution contaminated water on all continents and that the activities associated with the highest levels included the dumping of rubbish along the banks, insufficient sewage treatment infrastructure and the dumping of contents septic tanks residuals in rivers.
Researchers hope that by increasing surveillance pharmaceutical products in the environment, they will be able to develop strategies to limit the effects potentially caused by the presence of pollutants. “The study made it possible, for the first time, to draw up a representative inventory of drug pollution of rivers in the world, including many countries for which little or no information was available. This approach could be applied to other types of environment such as soils, or even living organisms, in order to develop international networks of pollution monitoring. “, concludes the Inrae on this subject.