There is huge uncertainty about what effects these mixtures of chemicals could have on wildlife and human health
Multiple pesticides are present in rivers and canals across Europe, according to a study by Greenpeace Research Laboratories at the University of Exeter.
The study tested samples from 29 waterways in the UK, Austria, Belgium, Germany, Denmark, France, Italy, the Netherlands, Poland and Spain. Every river and canal tested contained pesticides, while veterinary drugs were also found in most samples.
In 13 of the waterways, concentrations of at least one pesticide exceeded European standards for acceptable levels. The highest levels of contamination were found in a Belgian canal that contained 70 pesticides.
“There is huge uncertainty about what effects these mixtures of chemicals could have on wildlife and human health,” said Dr Jorge Casado, who led the analysis.
Even if chemicals are at concentrations that might not individually cause concern for human and wildlife health, it is not yet known what effect complex and variable exposure to harmful chemicals could have, he said.
The researchers said the presence of unlicensed pesticides did not necessarily mean they had been used illegally, as they could have been used for other permitted purposes or before bans came into force or licenses expired.
However, they noted that several pesticides were found in multiple rivers, and said the concentration and frequency of carbendazim – a fungicide known to be harmful to health, found in 93% of samples – was “remarkable”.
Dr Paul Johnston, who co-authored the paper, said that reliance on pesticides and veterinary drugs should be reduced through more sustainable agriculture.
Catherine Early is a freelance environmental journalist and chief reporter for the Ecologist. She can be found tweeting at @Cat_Early76.