Microplaastics as potential bisphenol carriers: role of adsorbents, adsorbates, and environmental factors.

Microplastics (MPs) are widely found in the environment and can act as carriers for various toxic substances, promoting their diffusion and bioenrichment. Accordingly, it is necessary to investigate the transfer of MPs between the environment and organisms. This study investigated the adsorption potential of four types of MPs, namely polystyrene (PS), polypropylene (PP), polyamide (PA), and polyvinyl chloride (PVC), for bisphenol (BP) A, B, F, and S (BPA, BPB, BPF, and BPS, respectively). The results showed that all four types of MP could act as environmental carriers of BP. PA had the highest BPA adsorption capability, with a value of 109.0 ± 39.93 µg·g-1, followed by PS (89.24 ± 26.12 µg·g-1), PVC (53.08 ± 15.32 µg·g-1), and PP (41.83 ± 11.51 µg·g-1).Thepolymer type, SSA, and surface functional groups were the main factors affecting the BP adsorption capacity of MPs. The concentration, hydrophobicity, and dissociation ability of BPs also substantially affected their adsorption behavior. The adsorption efficiency of different BPs on the same MPs ranged from 37.4 ± 3.7% to 59.1 ± 2.8%. The adsorption capacity of BPs on MPs decreased with increasing temperature. Salt ions in the solution significantly enhanced BP partitioning in the solid phase owing to the salting-out effect. Additionally, the adsorption of BPs on MPs was pH dependent. Higher pH values increased electrostatic repulsion, which decreased the adsorption capacity. These results demonstrate that MPs can serve as BP carriers in the environment and their potential BP loads might be considerably greater than that of BP additives used during plastic production.

Ingestion of microplastics by silver carp (Hypophthalmichthys molitrix) larvae: Quantification of ingestion and assessment of microbiota dysbiosis.

The adverse effects of microplastics ingested by aquatic organisms have been reported previously. However, most studies are primarily qualitative; therefore, it is challenging to determine the direct interactions between microplastics and organisms. In this study, for the first time, the microplastic intake behavior of silver carp (Hypophthalmichthys molitrix) larvae, a popular fish in China, as well as intestine accumulation and excretion of the microplastics were quantitatively investigated. The results showed that the intake of microplastics by silver carp larvae was negatively correlated with the particle size of microplastics but positively correlated with the exposure concentration. After intaking microplastics of different sizes, small-sized microplastics (≤ 150 µm) were rapidly excreted from the intestine of silver carp, whereas some large-sized microplastics (≥ 300 µm) remained in the intestine for a long time. The presence of food significantly increased the intake of large-sized microplastics, while small-sized microplastics intake was unaffected by the food. More importantly, the ingested microplastics caused specific changes in the diversity of intestinal microflora, potentially leading to abnormal immune and metabolic functions. The results of this study provide a new understanding on the potential impacts of microplastics on aquatic organisms.