Role of mushroom substrate in the transfer of fungicide residues to Agaricus bisporus

White button mushroom (Agaricus bisporus) is a significant component of the human diet due to its nutritional value, which includes digestible proteins, dietary fiber, phenolic compounds, and B-group vitamins. In recent years, interest in organic agricultural products has increased, accompanied by growing demands for food quality and safety. Organically cultivated edible fungi, produced without the use of plant protection products, are generally expected to be safe and health-promoting. However, despite the application of organic production methods, the presence of pesticide residues in mushrooms remains possible, thus requiring comprehensive analysis.This study aimed to evaluate the presence of plant protection products residues in mushroom fruiting bodies cultivated using substrates from conventional and organic sources. A total of 158 mushroom samples and 128 substrate samples were analysed using QuEChERS-based methods to assess whether the growing substrate facilitates the pesticide transfer to mushrooms. The results revealed significant differences between organic and conventional mushrooms. However, residues in mushrooms were detected even without the direct application of pesticides during cultivation, indicating that chemical substances can be transferred from the substrate to fruiting bodies. The presence of residues in mushrooms labeled as organic suggests that substrate contamination is an underestimated pathway for pesticide transfer. The findings emphasize the need for more precise regulation of substrate materials employed in mushroom cultivation, particularly within organic systems, to ensure food safety and compliance with residue limits. Monitoring mushroom substrates is crucial for developing sustainable and safe agricultural practices.