Effects of Pharmacological and Agrochemical Endocrine Disruptors on Human Sperm Mitochondrial Respiration: Evidence from Ex Vivo Bioenergetic Profiling

Background: Human exposure to endocrine-disrupting chemicals (EDCs) is increasingly linked to male reproductive dysfunction, but underlying mechanisms remain unclear. This study aimed to evaluate how selected pharmacological (dihydroxyflutamide, 2OH-FTA; bicalutamide, BIC) and agrochemical (lindane, βHCH; permethrin, PERM; mancozeb, MNZ; tributyltin oxide, TBTO) EDCs affect mitochondrial function in human spermatozoa with parameters within World Health Organization (WHO) reference ranges. Methods: Human sperm cells were exposed ex vivo to 0.1-1000 nM of each compound. Mitochondrial respiration was measured using polarography, assessing oxygen consumption in active (V₃) and resting (V₄) states, and the respiratory control ratio (RCR) was calculated as an index of mitochondrial coupling. Results: Both 2OH-FTA and BIC reduced RCR in a concentration-dependent manner, mainly due to increases in V₄, with BIC showing the strongest effect. βHCH produced a similar pattern, elevating V₄ and decreasing RCR. In contrast, PERM, MNZ, and TBTO caused near-complete collapse of both V₃ and V₄ even at sub-nanomolar concentrations, indicating severe, concentration-independent mitochondrial toxicity. Conclusions: Sperm mitochondria are highly sensitive to EDCs, and distinct compounds exert different bioenergetic effects. Mitochondrial respiration assays provide a useful tool for ex vivo toxicological screening and risk assessment.