Posts tagged: waterways

Scientists Find 24 Banned Pesticides, Neonicotinoids and Veterinary Drugs In 100% Of Tested European Waterways

Scientists Find 24 Banned Pesticides, Neonicotinoids and Veterinary Drugs In 100% Of Tested European Waterways
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In a 2019 study [1] appearing in Volume 670 of Science of The Total Environment, a group of British researchers sampled water from up to 29 waterways, spread across 10 European Union countries – and their findings were troubling.

According to Casado et al. (2019) from the University of Exeter, all rivers (yes, 100%) in the study tested positive for pesticides and veterinary drugs. In particular, the researchers found 21 veterinary drugs and 103 pesticides, including 24 banned compounds.

The study employed solid-phase extraction, liquid chromatography, and Orbitrap high-resolution tandem mass spectrometry testing techniques to measure the levels of pesticides and veterinary drugs in the water samples. These methods meant that only a certain category of pesticides could be detected.

It’s worth noting that some common pesticides such as chlorothalonil and glyphosate were not part of the study. So as remarkable as the levels of contamination seem, they are merely the tip of the iceberg – the bare minimum.

In one Belgian canal, the scientists measured up to 70 different pesticides, making it the highest level of contamination recorded in the study. Even more concerning, nearly 50% of the tested waterways had concentrations that exceeded the acceptable standard under European guidelines.

Although they found 24 unlicensed pesticides, the researchers were hesitant to raise red flags on the matter, citing the possibility that the contamination could have happened before the bans. Regarding veterinary drugs, most of them were antimicrobials such as widely used antibiotics.

The high levels of pesticides and veterinary drugs in the waterways suggest the possibility of complex mixtures, whose collective impact is currently unknown. The contamination is mainly a health risk for wildlife, and it may even facilitate the development of drug-resistant microbes. Paul Johnston, one of the researchers in the study, highlighting the risk to humans by drawing attention to resistant fungal infections in hospitals, which are a cause for concern.

Similar to the study by Casado et al. (2019), Swiss researchers [2] ecently found that 80% of wildlife areas and a remarkable 93% of organic farms in Switzerland were contaminated with pesticides. An earlier study published in the PloS one Journal by Dutch researchers [3] also claimed that a common insecticide was devastating water-based species such as snails and dragonflies in the Netherlands. These negative statistics explain the plummeting population of birds and insects that rely on water sources for food. See also further analysis and critique of the Dutch study published my PloS One in 2014. [4]


[1] Casado, J., Brigden, K., Santillo, D., & Johnston, P. (2019). Screening of pesticides and veterinary drugs in small streams in the European Union by liquid chromatography high resolution mass spectrometry. Science of The Total Environment, 670, 1204-1225.

[2] Pesticide residues found on 93% of organic Swiss farms. Retrieved 18 October 2019, from–of-organic-swiss-farms/44878988

[3] Van Dijk, T. C., Van Staalduinen, M. A., & Van der Sluijs, J. P. (2013). Macro-invertebrate decline in surface water polluted with imidacloprid. PloS one, 8(5), e62374.

[4] Martina G. Vijver, Paul J. van den Brink (2014) Macro-Invertebrate Decline in Surface Water Polluted with Imidacloprid: A Rebuttal and Some New Analyses.