Environmental pollutants have become quite ubiquitous over the past two centuries; of those, plastics, and in particular, microplastics (<5 mm), are among the most pervasive pollutants. Microplastics (MPs) have found their way into the air, water system, and food chain and are either purposely produced or are derived from the breakdown of larger plastic materials. Despite the societal advancements that plastics have allowed, the mismanagement of plastic waste has become a pressing global issue. Pioneering studies on MPs toxicity have shown that exposure to MPs induces oxidative stress, inflammation, and decreased cell viability in marine organisms. Current research suggests that these MPs are transported throughout the environment and can accumulate in human tissues; however, research on the health effects of MPs, especially in mammals, is still very limited. This has led our group to explore the biological and cognitive consequences of exposure to MPs in a rodent model. Following a three-week exposure to water treated with fluorescently-labeled pristine polystyrene MPs, young and old C57BL/6J mice were assessed using behavioral assays, such as open-field and light–dark preference, followed by tissue analyses using fluorescent immunohistochemistry, Western blot, and qPCR. Data from these assays suggest that short-term exposure to MPs induces both behavioral changes as well as alterations in immune markers in liver and brain tissues. Additionally, we noted that these changes differed depending on age, indicating a possible age-dependent effect. These findings suggest the need for further research to better understand the mechanisms by which microplastics may induce physiological and cognitive changes.

Micro- and nanoplastics (NMPs) have recently gained attention as one of the most pervasive and potentially dangerous environmental pollutants. An increasing number of studies have explored the presence and potential health consequences of NMPs exposure, leading to calls for techniques to assess their bioaccumulation. Significant gaps that remain in this growing field of research are methodologies to quantify discrete particle counts of NMPs below 5 μm in size and evaluate the recovery rate of such methods to ensure accuracy and comparability across studies. To address these gaps, we aimed to develop a high-throughput protocol for the extraction, isolation, and quantification of a 1:1 volume mixture of 2 and 0.1 μm pristine fluorescently labeled spherical polystyrene NMPs (PS-NMPs) from mouse tissue, and to determine recovery rates of both sizes to assess the success of the methodology. We found that we were able to successfully recover 85% of 2 μm NMPs and 30% of 0.1 μm NMPs, and that this workflow could be applied to tissues from mice experimentally exposed to a concentration gradient of PS-NMPs to detect differences in accumulation. This methodology is the first to attempt a continuous workflow to assess particle counts of both micro- and nanoplastics from biological tissues, including calculations of recovery rates, and we anticipate that the workflow described here may be applied and modified in future studies to answer outstanding questions regarding the accumulation of small NMPs that may not be addressed with traditional techniques. Additionally, in identifying the significant differences in recovery rates for micro- versus nanoplastics, we highlight the considerations that must be taken into account for nanoplastics that are often not discussed within the NMPs literature.