Assessment of pesticide contamination and related ecotoxicological risks in soils of the Loukkos area (Larache, Morocco).

The intensive use of pesticides in the province of Larache results in soil contamination, which negatively impacts microbial communities and non-target organisms, including key soil species such as earthworms. The present study is the first in the region to combine measurements of environmental concentrations of pesticides with an ecological risk assessment for the Loukkos agroecosystem. Two approaches were used to assess and characterize the potential ecotoxicological risks of the 11 pesticide residues detected: the Risk Quotient (RQ) and the Toxicity-exposure ratio (TER). Fenamiphos and chlorpyrifos ethyl were the most frequently detected pesticides, with concentrations ranging from 0.072-0.229 and 0.010-0.023 mg/kg, respectively. These concentrations are particularly high, especially for fenamiphos. The RQ and TER values revealed high ecological risk and an intolerable level of risk for some pesticides, particularly cypermethrin and fenamiphos, with RQ values reaching up to 26.200 and 46.780, respectively, in certain locations. These two compounds pose potential risks to earthworms. The other molecules exhibited low to moderate risk levels. Overall, the pesticides detected in soil samples showed varying levels of risk to earthworms, mainly attributed to organophosphate compounds.