Microplastics in Tai lake food web: Trophic transfer and human health risk assessment

Harmful effects of true-to-life nanoplastics derived from PET water bottles in human alveolar macrophages

The increasing presence of secondary micro/nanoplastics (MNPLs) in the environment requires knowing if they represent a real health concern. To such end, an important point is to test representative MNPLs such as the denominated true-to-life MNPLs, resulting from the degradation of plastic goods in lab conditions. In this study, we have used polyethylene terephthalate (PET) NPLs resulting from the degradation of PET water bottles. Since inhalation is an important exposure route to environmental MNPLS, we have used mouse alveolar macrophages (MH-S) as a target cell, and the study focused only on the cells that have internalized them. This type of approach is novel as it may capture the realistic adverse effects of PETNPLs only in the internalized cells, thereby mitigating any biases while assessing the risk of these MNPLs. Furthermore, the study utilized a set of biomarkers including intracellular reactive oxygen species (ROS) levels, variations on the mitochondrial membrane potential values, and the macrophage polarization to M1 (pro-inflammatory response) and M2 (anti-proinflammatory response) as possible cellular effects due to PETNPLs in only the cells that internalized PETNPLs. After exposures lasting for 3 and 24 h to a range of concentrations (0, 25, 50, and 100 μg/mL) the results indicate that no toxicity was induced despite the 100% internalization observed at the highest concentration. Significant intracellular levels of ROS were observed, mainly at exposures lasting for 24 h, in an indirect concentration-effect relationship. Interestingly, a reduction in the mitochondrial membrane potential was observed, but only at exposures lasting for 24 h, but without a clear concentration-effect relationship. Finally, PETNPL exposure shows a significant polarization from M0 to M1 and M2 subtypes. Polarization to M1 (pro-inflammatory stage) was more marked and occurred at both exposure times. Polarization to M2 (anti-inflammatory stage) was only observed after exposures lasting for 24 h. Due to the relevance of the described biomarkers, our results underscore the need for further research, to better understand the health implications associated with MNPL exposure.

Probabilistic risk assessment of microplastics in Tai Lake, China

Microplastics are a global environmental concern, especially in freshwater ecosystems. Despite the studies in specific regions of Tai lake, a gap persists in understanding the comprehensive risk of MPs across the entire watershed. Therefore, this study offers an overview of MPs abundance and assesses ecotoxicological risk by employing acute and chronic species sensitivity distributions, which consider the effects triggered by MPs. The concentrations of MPs ranged from 0 to 18.6 particles/L within the lake, 1.56 to 1.42 × 102 particles/L in the rivers, and 0.16 to 0.7 particles/L in the estuaries. Certain areas, particularly the northwest and southeast regions, exhibit higher concentrations. Using existing toxicity data, this study calculated predicted no effect concentrations for acute and chronic exposure of MPs to freshwater species, resulting in values of 11.5 and 31.72 particles/L, respectively. The probabilistic risk assessment indicates that the average risk possibility of MPs in Tai lake was 16 %. Moreover, the risk characterization ratio indicated that 22 % of the locations in Tai lake showed an acute ecological risk, while 7.4 % exhibit a chronic ecological risk. The assessment concluded that MPs reported in the literature could pose a considerable risk to Tai lake biota. However, the risk associated with MPs followed descending order: river >lake > estuary waters. Our research supplies valuable insights for the assessment of ecological risks associated with MPs on a whole watershed scale.

Modeling the effect of fish migration on the horizontal distribution of microplastics in freshwater and ecological risks in the food web: Influence of habitat

Microplastics (MPs < 5 mm) pollution is a widespread phenomenon in freshwater ecosystems. While the role of physiochemical factors in the migration and distribution of MPs is understood, the impact of biological migration remains less clear. The influence of nekton migration determined by habitat suitability on the distribution of MPs and the consequent ecological risks to the regional food web is investigated in the freshwater environment by using Baiyangdian Lake (China) as a case study. The key findings reveal that fish migration significantly alters the horizontal distribution of MPs in the water environment, with a higher degree of fish aggregation in high suitability habitats leading to an increased presence of MPs due to their ingestion and excretion behaviors. In both high and low suitability habitats, MPs are found to bioconcentrate in fish, suggesting a significant risk to aquatic ecosystems. Despite the lack of evidence supporting MPs biomagnification, the results indicate that MPs are more likely to be biomagnified within the food web of high suitability habitats due to the enhanced foraging capabilities of aquatic organisms. These findings highlight the critical need to consider biological factors, such as nekton migration, in understanding and addressing MPs pollution in freshwater ecosystems.