First Global Analysis Shows How Pesticides Leach Into the Environment – University of Sydney

About three million tonnes of agricultural pesticides are used across the globe each year, yet little is known about where or in which environments these chemicals end up after their initial application.

A global study published Thursday in Nature, which analysed the geographic distribution of 92 of the most commonly used agricultural pesticides, found that approximately 70,000 tonnes of potentially harmful chemicals leach into aquifers each year, impacting ecosystems and freshwater resources.

Associate Professor Federico Maggi, the study’s lead author from the University of Sydney’s School of Civil Engineering, said: “Our study has revealed that pesticides wander far from their original source. In many cases these chemicals end up a long way downstream and often, though in much smaller amounts, all the way to the ocean.”

The study showed that about 80 percent of applied pesticides degrade into daughter molecules – or byproducts – into soil surrounding crops.

“This degradation of pesticides often occurs as a ‘cascade’ of molecules into the surrounding environment, which can persist in the environment for a long time and can be just as harmful as the parent molecule or applied pesticide.