19 July 2023
Global report says governments need to be more specific when looking to reduce chemicals' use.
MORE statistics information needs to be shared by national governments regarding the effects of pesticides' use, the authors of a new scientific paper have stated.
Around 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, according to researchers of a new global study.
The study published in 'Nature', analysed the geographic distribution of 92 of the most commonly-used agricultural pesticides. It found that approximately 70,000 tonnes of potentially-harmful chemicals leach into aquifers each year, impacting ecosystems and freshwater resources.
The study showed that about 80% of applied pesticides degrade into daughter molecules – or byproducts – into soil surrounding crops.
Associate Professor Federico Maggi, the study’s lead author from the University of Sydney’s School of Civil Engineering, said: “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. One such example is glyphosate. Although it is highly degradable, it breaks down into a molecule known as AMPA that is both highly persistent and toxic,” Federico said.
While the study found that only a fraction of pesticides enter river systems after field application, once in the water most of the active ingredients end up in the ocean.
“On paper, 0.1% leaching into fresh waterways might not sound like much. But it only takes a tiny amount of pesticides to have a negative impact on the environment,” Federico said.
The study showed that 730 tonnes of pesticides enter rivers each year, with about 13,000 kilometres of rivers reaching chemical concentrations above safety limits for a number of aquatic plants and invertebrates, with poorly understood consequences on rivers’ ecosystems.
Dr Fiona Tang, a lecturer in water engineering at Monash University and paper co-author said: “Just because we don’t see pesticide residues in soil and water doesn’t mean they’re not there, impacting critical systems on land, rivers and oceans.”
The research team used a large collection of publicly-accessible geospatial data to conduct the study.
However, the authors say the paper is a conservative estimate because the analysis did not include legacy pesticides and those used in aquaculture, private dwellings and public spaces, therefore actual figures could be higher.
Federico has co-authored a separate paper in Nature Ecology and Evolution in which his recommendations include calling for a reliable set of indicators and improved monitoring when looking to reduce pesticide use.
Lowering pesticide pollution should be focused on decreasing risk, including reducing amounts and toxicity, because some organisms are at high risk even from low quantities, the paper states.
"It is important that national authorities disclose statistics on the use of agricultural inputs, be they fertilisers or pesticides, given the effect they have on the environment and ecosystem service,” Federico said.
A global reduction in pesticide use, while maintaining food security, is possible as long as such initiatives are designed and implemented in consultation with food producers, he added.
“Globally, there is a lot of room to increase efficiencies and yield while still supporting an abundant food supply through new technology and modern crop management practices,” he said.
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