Reliability of pesticide toxicity evaluation: Effects of pesticides on cellular respiration under conventional versus physiological growth conditions.

The use of pesticides to enhance crop yields remains prevalent despite persistent concerns about their potential harmful side effects. Moreover, most cell viability studies are conducted in growth media and oxygen concentrations that do not accurately reflect the in vivo conditions in tissues, and therefore may influence the outcomes of toxicity assessments. The aim of the study was to examine how culture conditions alter the influence of pesticides on mitochondrial energy production. For this purpose, two cell lines - Caco-2 (human colorectal adenocarcinoma cells) and HepG2 (a human hepatoma cell line) - were cultured over an extended period with low doses of three widely used plant protection products: the fungicide boscalid, the herbicide glyphosate, and the insecticide NeemAzal. Cells were grown in conventional DMEM and Plasmax media, the latter resembling blood plasma composition, under normoxic (19 %) and physoxic (5 %) oxygen concentrations. High-resolution respirometry was employed to assess pesticide-induced alterations on mitochondrial metabolism and to evaluate how these effects differed between conventional and physiologically relevant environments. The results revealed minimal alterations with NeemAzal exposure, while boscalid induced the most pronounced effects, including a decreased mitochondrial bioenergetics index, reduced ATP-synthase-linked oxygen consumption, and impaired respiration associated with respiratory chain complexes I and II. Notably, these impairments in mitochondrial energy production were more pronounced in cells cultured in Plasmax media compared to DMEM. These findings highlight the critical importance of mimicking tissue-specific conditions, such as media composition and oxygen tension, in toxicity studies to obtain more accurate and physiologically relevant insights.