The ubiquity of plastics is a concern for the health of humans and marine ecosystems. Plastics and their composite endocrine disrupting chemicals (EDCs) are associated with adverse health outcomes in humans and marine species. With continued plastic production, waste mismanagement and global population increases, exposure effects will continue to escalate. The ‘One Health’ paradigm describes ‘health’ as a cross-species universal ‘good’. Adverse outcomes from plastic exposure are shared cross-species, indicating common mechanisms of toxicity. Marine species with individuals ingesting naturally disparate levels of plastic present valuable opportunities for researchers in understanding the real-world impacts of plastic. Sampling from sentinels monitors dynamic exposures to the evolving plastics landscape, allowing transcriptomic and epigenetic adaptations to these exposures to be assessed. Advances in bioinformatics enable elucidation of shared biological pathways from plastic toxicity in a systems level context. This review examines microplastics in the marine environment, adverse health exposure outcomes, and the exploitation of marine sentinel species in this context to elucidate the impacts of plastics. Hierarchical priorities when selecting marine plastic sentinels are explored. Abundant seabirds such as the herring gull or the northern fulmar represent ideal marine plastic sentinels.