1 February 2024

“Further investigation is needed on nanopesticides,” Dutch researchers say

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According to four scientists at Leiden University, current assessments of nanopesticides do not take into account some problems related to their use

by Matteo Cavallito

 

The potential environmental risks associated with the use of nanopesticides may not have been sufficiently examined. This is the hypothesis put forward by four scientists from Leiden University in the Netherlands in the journal Environmental Science & Technology.

“While we recognize that some of the reported functionalities of nanoenabled pesticides may indeed hold potential for more efficient means of crop protection,” they say, “we argue that claims regarding reduced environmental risks are often based on premises that insufficiently address their specific exposure and hazard profiles.”

Nanopesticides

Nanopesticides are phytopharmaceuticals characterized by a special structure composed of nanoparticles containing the substance used to tackle harmful microorganisms. These tools are developed to provide efficient distribution of the substance while limiting waste and environmental impact. Traditional pesticides tend to adhere to the upper layers of the soil. In this way, the risk is that only a small part of the substance is able to reach the roots of the plant.

To overcome this problem, large amounts of product can be used deliberately, but this strategy increases the likelihood of soil and water contamination. With obvious health consequences.

Created through nanoengineering, the microparticles used in the newly developed products – made of metal or organic material – “may be released slowly or only under optimal (weather) conditions,” a statement from Leiden University says. “This allows them to work for a longer period in the field and reduce leaching and runoff into surface water.” But this does not mean an absence of risk.

Less use but more downside?

According to ecotoxicologist Tom Nederstigt, one of the four signatories to the article, the assessments conducted so far seem to underestimate two particular characteristics of nanopesticides: their tendency to act over a longer period of time and their greater toxicity compared to traditional products.

“In practice, this could mean that use and emissions are smaller, but the downsides for nature are greater,” the authors explain.

The risk, in short, is that other particularly valuable soil organisms such as invertebrates and microbes will be exposed to the substance over a longer period of time. Moreover: “Assessors should also examine whether the product ends up in groundwater and neighbouring areas,” the researchers continue.

Pay attention to product characteristics

Finally, the authors note how internationally developed guidelines for nanopesticides are still largely under development. Hence they call for evaluators to focus on the effects on non-target organisms of products while taking into account the longer duration of exposure.

“We iterate the importance of considering trade-offs between usage volumes and exposure and hazard profiles that could concomitantly arise from their enhanced efficiency,” the researchers write.

Moreover, “We therefore contend that risk assessment of nanoenabled pesticides requires quantitative and mechanistic consideration of the specificity of obtained functionalities between target and nontarget organisms, including exposure durations and bioavailability, as well as indirect routes of exposure.”