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Succinate dehydrogenase inhibitor (SDHi) fungicides are used to control fungal proliferation, which affects yields in cereal, fruit, and vegetable crops, and may cause adverse health effects. Their mode of action relies on blocking the activity of succinate dehydrogenase (SDH), an enzyme that exists in all eukaryotes with mitochondria. SDH is involved in two interconnected metabolic processes for energy production: cellular respiration, whereby it enables the transfer of electrons in the mitochondrial respiratory chain, and the Krebs cycle, whereby it catalyzes the oxidation of succinate to fumarate. In humans, inherited SDH deficiencies can induce encephalopathies and cancers. The cellular and molecular mechanisms related to the genetic inactivation of SDH have been well described in certain tumors, where it induces oxidative stress, a pseudohypoxia phenotype, metabolic, epigenetic, and transcriptomic remodeling, and alterations in the migration and invasion capacities of cancer cells, along with the accumulation of an oncometabolite, the succinate, following SDH inactivation. The use of SDHi fungicides has raised many questions in recent years. Their mode of action, which aims at altering mitochondrial functions essential for energy production and metabolic homeostasis, is not specific to fungi, suggesting that they could also be toxic to humans and biodiversity. The impact of SDHis on health remains largely unexplored to date, with a significant lack of data on exposure to these substances and impregnation data concerning farmers and the general population. In addition, the physicochemical properties of SDHis make them potentially persistent in soils and organisms, and a growing number of studies report the toxic effects of SDHis in non-target species. The analysis of regulatory assessment reports shows that most SDHi substances induce tumors in animals, with no evidence of genotoxicity. Thus, for these substances, the mechanisms of carcinogenicity have not yet been clearly established and their elucidation would require the development of regulatory evaluation procedures which better integrate knowledge of carcinogenesis processes which has been acquired over the last ten years.