Mechanistic insights into microplastic-induced reproductive toxicity in aquatic organisms: A comprehensive review

Microplastics (MPs) are widespread contaminants in aquatic ecosystems and pose significant threats to both organisms and the environment. Their small size, high surface area, and capacity to adsorb toxic chemicals allow MPs to infiltrate food webs, affecting organisms across trophic levels. This review explores the intricate mechanisms by which MPs induce reproductive and endocrine toxicity, focusing on their physical and chemical properties, bioaccumulation dynamics, and associated molecular pathways. MPs interfere with hormonal homeostasis, oxidative stress responses, and apoptotic pathways, leading to disruptions in the hypothalamic-pituitary-gonadal axis, impaired steroidogenesis, and gonadal dysfunction. These effects manifest as reduced fertility, altered gametogenesis, and multigenerational reproductive impairments across diverse aquatic taxa. Furthermore, MPs serve as carriers for endocrine-disrupting chemicals, compounding their adverse effects on organisms and aquatic biodiversity. Through a synthesis of recent research, this review identifies key signaling pathways, including MAPK, PI3K-AKT, mTOR, NF-κB, PPAR and NLRP3 inflammasome, that may play a role in MP-induced reproductive toxicity. The findings underscore the urgent need for advanced mitigation strategies, regulatory frameworks, and further research to combat the ecological consequences of MP pollution. Prioritizing targeted interventions is essential to safeguard aquatic biodiversity and ensure ecosystem resilience against the pervasive threat of MPs.