Do the same doses of pesticides work for all soils?

Phytosanitary products raise concern, because their application can cause effects on some soil organisms that are not directed against, but that could be very sensitive to some pesticides.

The European Food Safety Authority (EFSA, which regulates agricultural practices, the use of phytosanitary products, etc., at a European level) developed a guide and a computer tool called PERSAM (Persistence in Soil Analytical Model) a few years ago, to carry out evaluations from exposure on the ground.

Members of the Cell Biology in Environmental Toxicology Group at the University of the Basque Country (UPV/EHU) have investigated how to improve the PERSAM model. They have analyzed the risks caused by four pesticides in two types of soil organisms in northern, central and southern Europe.

The work responds to a commission from the European Food Safety Authority to help improve the regulation of pesticides.

Until now, the PERSAM program helped to calculate the concentration that could be expected from a certain application of plant protection products. “Now we have managed to extrapolate the potential risks of these concentrations and the factors that influence that risk, not only considering the soil conditions, but also the type of crop and the type of pesticide used,” explains the UPV/EHU professor Manuel Soto.

Soil characteristics and environmental variables vary along the latitudinal axis that runs through the European continent. “If the toxicity is different depending on the characteristics of the soil, the logic of applying a single dose throughout Europe cannot be followed, since a dose may not have any effect in Sweden, but it does in Spain or France. , for instance. The EFSA wanted to make this differentiation, and they contacted our group because it was essential to develop an evaluation method based on the landscape that would take into account regional variability”, explains Erik Urionabarrenetxea, researcher at the UPV/EHU.

Erik Urionabarrenetxea (left) and Manu Soto, at the Plentzia Marine Station. (Photo: Tere Ormazabal – UPV/EHU)

In this sense, members of the Department of Zoology and Animal Cell Biology have investigated the effect that four pesticides have on two different types of organisms in different parts of northern, central and southern Europe. The study has been carried out with earthworms and springtails (beings from the group of arthropods, close to insects), because the earthworms are affected by the existing contamination in the soil and the springtails by the contamination present in the aqueous pores. ground. “Depending on the diet and needs of each organism, some are more vulnerable than others to contamination present in one or another soil compartment.” The research team believes that many factors must be taken into account when calculating risk.

Thus, in the study carried out, the team has verified that the risks derived from the concentrations vary greatly from one soil compartment to another. They have pointed out that this issue should be taken into account for the purpose of adjusting the regulations, as well as the possible variability of the landscape between the different Euroregions. “From north to south of Europe, great variability is observed, but also within each region,” they point out. Regarding the type of pesticides, they have also observed that “the characteristics of the pesticides greatly influence their distribution in each of the compartments”.

“It is a matter of better calculating the risk, and not just focusing on the concentrations, since they can be highly variable. It is important to look at the toxic effects produced by these concentrations, their potential effects and the risks that this entails, for their subsequent application to agricultural practices”, the researchers indicate. “Proposing the need to take into account the characteristics of the soil is a great advance, since until now it was not taken into consideration.”

The study is entitled “Predicting environmental concentrations and the potential risk of Plant Protection Products (PPP) on non-target soil organisms accounting for regional and landscape ecological variability in European soils”. And it has been published in the academic journal Chemosphere.

The team continues to work on this line of research: “Now we are analyzing the impact that all this would have from an ecological point of view,” the researchers indicate. (Source: UPV/EHU)