Plasticiser leaching from polyvinyl chloride microplastics and the implications for environmental risk assessment

A Study of Plant-Filled Polymer Composites Based on Highly Plasticized Polyvinyl Chloride

To enhance the ecological properties of polyvinyl chloride (PVC) products, the fabrication of PVC-based composites using biofillers with acceptable performance characteristics could be considered. In this work, plant-filled PVC-based composite materials were fabricated and their optical, structural, thermal, and mechanical properties, depending on the nature of the filler, were studied. Spruce flour, birch flour, and rice husk were used as fillers. Optical measurements showed the selected technological parameters, allowing films with a uniform distribution of dispersed plant filler in the polymer matrix to be obtained. Using the plant fillers in PVC films leads to a reduction in strength characteristics; for instance, the tensile strength changed from 18.0 MPa (for pure PVC film) to ~7 MPa (for composites with 20 wt.% of fillers), and to ~5-6.2 MPa (for composites with 40 wt.% of fillers). Thermal investigations showed that the samples with plant fillers could be used at low temperatures without changing their operating characteristics. Thus, plant-filled PVC-based composite materials have a wide operating temperature range, from-65 °C to 150 °C. TGA analysis has demonstrated that the rice husk affected the thermal stability of the composites by increasing their thermal decomposition resistance. The ability to absorb water was observed during the investigation of water absorption of the samples. And the highest degree of water absorption (up to 160 mg/g) was detected for the sample with 40 wt.% of rice husk. In general, plant-filled polymer composites based on PVC can be used on an equal basis with unfilled PVC plastic compounds for some applications such as in construction (for example, for design tasks).

Distribution patterns and environmental risk assessments of microplastics in the lake waters and sediments from eight typical wetland parks in Changsha city, China

The quality of water in urban parks is closely related to people's daily lives, but the pollution caused by microplastics in park water and sediments has not been comprehensively studied. Therefore, eight typical parks in the urban area of Changsha, China, were selected, and Raman spectroscopy was used to explore the spatial distributions and compositions of the microplastics in the water and sediments, analyze their influencing factors, and evaluate their environmental risks. The results showed that the abundances of surface water microplastics in all parks ranged from 150 to 525 n L-1, and the abundances of sediment microplastics ranged from 120 to 585 n kg-1. The microplastics in the surface water included polyethylene terephthalate (PET), chlorinated polyethylene (CPE), and fluororubber (FLU), while those in the sediments included polyvinyl chloride (PVC), wp-acrylate copolymer (ACR), and CPE. Regression analyses revealed significant positive correlations between human activities and the abundances of microplastics in the parks. Among them, the correlations of population, industrial discharge and domestic wastewater discharge with the abundance of microplastics in park water were the strongest. However, the correlations of car flow and tourists with the abundance of microplastics in park water were the weakest. Based on the potential ecological risk indices (PERI) classification assessment method, the levels of microplastics in the waters and sediments of the eight parks were all within the II-level risk zone (53-8,549), among which the risk indices for Meixi Lake and Yudai Lake were within the IV risk zone (1,365-8,549), which may have been caused by the high population density near the park. This study provides new insights into the characteristics of microplastics in urban park water and sediment.

The combined effects of microplastics and bisphenol-A on the innate immune system response and intestinal microflora of the swimming crab Portunus trituberculatus

Microplastics (MPs) and bisphenol-A (BPA) have been shown to have toxic effects on aquatic organisms. However, data on the combined effects of MPs and BPA on the innate immune system response and intestinal microorganisms of crabs are limited. Here, Portunus trituberculatus were exposed to BPA (at a concentration of 100 μg/L), MPs (microbeads of polystyrene with a particle size of 1 µm and at a concentration of 1 × 106 particles/L) or BPA+MPs for 21 days were tested at the tissue, cellular, and molecular levels. The results showed that neither the single nor combined exposure of MPs and BPA had a significant impact on the growth of crabs. However, intestinal histology study found that the intestinal villi of crabs in the BPA treated group, MP treated group and MP+BPA treated group appeared abnormal. Overall, compared with the control group and the single pollutant exposure group, co-exposure to the MP and BPA generally led to a significant increase in MDA and SOD activity and a significant decrease in CAT activity, and the activation of MyD88, Crustin-1, TARF6, Cu/Zn-SOD, Lyz, Toll-2 and NOX gene expression levels were significantly up-regulated. Co-exposure induced disorders of the intestinal microbial community of crabs, resulting in an increase in the abundance of harmful bacteria and a decrease in the abundance of beneficial bacteria. This study shows that the combined exposure of MPs and BPA can exacerbate the intestinal toxicity of a single pollutant to P. trituberculatus.