This review synthesizes research on mechanisms of microplastic-induced mitochondrial damage, focusing on oxidative stress and inflammation to address the mechanistic pathways linking microplastic exposure to mitochondrial dysfunction and cellular toxicity. Analysis of diverse in vitro and in vivo studies across aquatic, terrestrial, and mammalian systems was conducted, emphasizing molecular, cellular, and functional mitochondrial parameters. Findings reveal consistent microplastic-induced reactive oxygen species generation, disrupting mitochondrial membrane potential and bioenergetics, with smaller and aged particles exerting greater toxicity. Inflammatory signalling via NF-κB, the NLRP3 inflammasome, and immune cell necroptosis is closely associated with oxidative stress, forming a feedback loop that exacerbates mitochondrial impairment. Molecular mechanisms implicate endocytic uptake pathways, mitochondrial calcium dysregulation, and apoptosis-related cascades, though causal validation remains limited. The interplay between oxidative stress and inflammation emerges as a central driver of mitochondrial damage across models. These integrated insights highlight the critical influence of microplastic physicochemical properties and biological context on mitochondrial and inflammatory responses. The findings inform future mechanistic research and underscore the need for standardized models to assess microplastic toxicity, advancing understanding of environmental and human health risks associated with microplastic pollution.

Microplastic (MP) and nanoplastic (NP) pollution has emerged as a pervasive and still insufficiently quantified pressure on terrestrial ecosystems, yet its consequences for wild herbivores remain incompletely understood. As key links between primary producers and higher trophic levels, wild herbivores occupy a critical ecological position and may serve both as exposed receptors and as biological vectors of plastic contamination. This manuscript presents a narrative review that synthesizes recent advances in understanding the physiological, behavioural, and ecological implications of MP and/or NP exposure in free-ranging herbivorous mammals, integrating evidence from field surveys, experimental studies, ecological modelling, and supportive mechanistic findings from livestock and experimental mammalian systems. Available evidence indicates that MPs and NPs are consistently detected in wild herbivores from both human-modified and protected landscapes, demonstrating widespread terrestrial exposure. Reported biological effects include oxidative stress, digestive dysfunction, inflammatory and immune responses, altered gut microbial communities, impaired nutrient assimilation, and organ-level damage, although much of the mechanistic evidence derives from controlled laboratory or livestock-based studies rather than direct wildlife investigations. Behavioural responses remain comparatively underexplored, particularly in large-bodied herbivores, with limited evidence for altered foraging, habitat use, and stress-related behaviours. At the ecosystem level, emerging studies suggest that herbivores may contribute to the landscape-scale redistribution of MPs and NPs through movement and faecal deposition, with potential downstream effects on soil processes, nutrient cycling, and plant–herbivore interactions. However, the current evidence base is constrained by major methodological and conceptual limitations, including the lack of standardized detection and reporting protocols, limited ecological realism in exposure studies, taxonomic and geographic biases, and poor resolution of long-term population-level and food-web consequences. Overall, the available literature indicates that MP and NP pollution represent a multifaceted and emerging risk to wild herbivores and the ecosystems they inhabit. Future research should prioritize standardized contamination-controlled monitoring, non-invasive faecal surveillance, ecologically realistic chronic exposure studies, and integrated conservation frameworks that recognize wild herbivores as sentinel species for terrestrial plastic pollution.