Bridging the Gap: How environmental exposures compromise male fertility and clinical Outlook.

The growing prevalence of male infertility has become a significant clinical and public health issue, with environmental exposures increasingly recognized as a major modifiable risk factor. This review synthesizes current evidence within the framework of the "male reproductive exposome", linking lifelong exposure to environmental toxicants-ranging from endocrine-disrupting chemicals to emerging contaminants-to clinically relevant outcomes such as impaired semen parameters, altered reproductive hormone profiles, and an increased risk of testicular dysfunction. We critically evaluate the concept of life-course vulnerability, highlighting how exposures during critical developmental windows-including prenatal, peripubertal, and adult stages-may program distinct pathological trajectories that manifest as reproductive disorders in later life. In addition to classical mechanisms of endocrine disruption, we emphasize oxidative stress and, particularly, epigenetic reprogramming of the germline as key biological pathways contributing to both immediate fertility impairments and potential transgenerational health effects. Furthermore, we discuss the translational importance of these insights, focusing on the development of mechanism-informed biomarker panels for early detection and risk stratification, as well as addressing the persistent challenge of assessing toxicity from complex chemical mixtures. Finally, we underscore the necessity of integrating epidemiological research, mechanistic toxicology, and clinical practice to advance preventive and clinical strategies. This integration requires overcoming methodological challenges in mixture exposure assessment, accelerating biomarker discovery for personalized risk prediction, and formulating evidence-based public health interventions. In a word, this review advocates for a proactive, science-driven approach to mitigate environmental threats to male reproductive health and protect the well-being of future generations.