A Narrative Review of Heavy Metals and Sperm Quality: The Interplay with Antioxidant Imbalance and Reactive Oxygen Species.

Reproductive infertility is characterized by the inability to achieve pregnancy after a year or more of unprotected sexual intercourse. This review highlights the significant impact of exposure to both types of heavy metals (essential and non-essential) on the reproductive performance of various species, particularly humans. Heavy metals present a high atomic density and weight, including lead, mercury, cadmium, nickel, chromium, and arsenic, and are delivered into the environment through natural and human activities, posing a threat to ecological systems and human reproductive health. These heavy metals have the potential for bioaccumulation and can adversely affect male fertility and sperm quality due to their role in disrupting endocrine functions, altering hormone levels responsible for sperm production, and inducing oxidative stress. The elevated production of reactive oxygen species (ROS) exceeds the capability of antioxidants and can lead to the alteration of sperm quality. Seminal fluid contains antioxidants like vitamin C, vitamin E, zinc, and selenium to counteract the impacts of ROS and also to preserve the sperm function. This review aims also to explore the impact of heavy metals on sperm quality and their relationship with antioxidant imbalance and ROS. The exposure to heavy metals whether through occupational or environmental means increases the production of ROS and therefore leads to an imbalance of antioxidants production. All these factors have no doubt an impact on male reproductive health.