Lead as a Reproductive Endocrine Disruptor in Aquatic Species and Agricultural Livestock

Lead (Pb) is a naturally occurring metal that is environmentally ubiquitous due to industrial activities, such as mining, smelting, and fossil fuel combustion. Exposure to Pb adversely affects the central nervous system, gastrointestinal tract, lungs, liver, bones, and cardiovascular system, leading to a multitude of negative health impacts, such as anemia and neurological disorders. While significant research has focused on the effects of Pb on the nervous and immune systems, Pb’s impact as a reproductive endocrine disruptor remains largely understudied. The first objective of this review was to collate the current literature regarding the effects of Pb on the reproductive system of aquatic species (primarily fish) and agricultural livestock to highlight the ecological significance and impacts on animal health. Literature supports the hypothesis that exposure to Pb can impede reproductive processes by affecting hormone levels, reproductive organ development, and fertility. A second objective of this review was to elucidate putative mechanisms underlying Pb as a reproductive endocrine disruptor using molecular data and computational approaches. Based on transcriptomics data, Pb is hypothesized to perturb key pathways important for hypothalamic–pituitary–gonadal axis functions, such as circadian regulation and estrogen receptor signaling. Given the widespread environmental presence of Pb, understanding these mechanisms is essential for improving risk assessments and protecting animal reproductive health.