[Research Progress on Characteristics of Human Microplastic Pollution and Health Risks].

Microplastic pollution is not only an environmental problem but also a social problem. Many studies have been conducted on the sources, abundance, and distribution of microplastics in the environment, but an understanding of human exposure levels and potential health risks remains very limited. Based on the bibliometric methods, the present review systematically summarized the exposure pathways of microplastics in humans, and then the characteristics and potential adverse impacts on human health were expounded upon. Available literature showed that microplastics in human bodies were mainly concentrated on sizes smaller than 50 µm, and polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) were the main polymers. Microplastics in environments entered human bodies mainly through food and respiratory pathways, then accumulated in lung and gastrointestinal tissues. Most importantly, small-sized microplastics could distribute in tissues and organs via the circulatory system. The results from lab-based toxicological experiments showed that microplastics not only posed threats to cell membrane integrity, immune stress, gut microbiota, and energy metabolism but also had potentially adverse impacts on the reproductive system. To further understand the health risks of microplastic pollution, it is necessary to promote research on the toxicological effects of microplastics as well as the inner mechanisms and also to establish risk assessment frameworks for evaluating microplastic pollution. These works are crucial to preventing the risks of microplastic pollution with scientific evidence.

Tissue accumulation of microplastics and potential health risks in human.

Microplastics have become ubiquitous throughout the environment. Humans constantly ingest and inhale microplastics, increasing concerns about the health risks of microplastic exposure. However, limited data impedes a full understanding of the internal exposure to microplastics. Herein, to evaluate microplastic exposure via the respiratory and digestive systems, we used laser direct infrared spectroscopy to identify microplastics >20 µm in size in different human tissues. Consequently, 20-100 µm microplastics were concentrated in all tissues, with polyvinyl chloride (PVC) being the dominant polymer. The highest abundance of microplastics was detected in lung tissue with an average of 14.19 ± 14.57 particles/g, followed by that in the small intestine, large intestine, and tonsil (9.45 ± 13.13, 7.91 ± 7.00, and 6.03 ± 7.37 particles/g, respectively). The abundance of microplastics was also significantly greater in females than in males (p < 0.05). Despite significant diversity, our estimation showed that the lungs accumulated the highest amounts of microplastic. Moreover, PVC particles may cause potential health risks because of their high polymer hazard index and maximal risk level. This study provides evidence regarding the occurrence of microplastics in humans and empirical data to support assessments of the health risks posed by microplastics.

Occurrence of microplastics in commercially sold bottled water.

Microplastics are ubiquitous in all environmental compartments, including food and water. A growing body of evidence suggests the potential health impacts of continuous microplastic ingestion on humans. However, a lack of information on microplastic exposure to humans through drinking water and the high heterogeneity of available data limits advancements in health risk assessments. In the present study, laser direct infrared spectroscopy (LD-IR) was used to determine the occurrence of microplastics in bottled water sold in China. Then, the ingestion level of microplastics through drinking water was estimated. The results showed that the average microplastic abundance in bottled water was 72.32 ± 44.64 items/L, which was higher than that detected in tap water (49.67 ± 17.49 items/L). Overall, the microplastic structures were dominated by films and mainly consisted of cellulose and PVC. Their sizes were concentrated in the range of 10-50 µm, accounting for 67.85 ± 8.40 % of the total microplastics in bottled water and 75.50 % in tap water. The estimated daily intake of microplastics (EDI) by infants through bottled water and tap water was almost twice as high as that by adults, although adults ingested more microplastics. The present results provide valuable data for further assessing human health risks associated with exposure to microplastics.

Microplastics transferring from abiotic to biotic in aquatic ecosystem: A mini review.

Microplastics have been detected in global aquatic ecosystems, so it is vital to understand the bioaccumulation and biomagnification of microplastics for ecological risk assessment. However, variability between studies, including sampling, pretreatment processes, and polymer identification methods have made it difficult to draw definitive conclusions. Alternatively, the compilation and statistical analysis of available experimental and investigation data provides insight into the fates of microplastics in an aquatic ecosystem. To reduce bias, we performed a systematic literature retrieval and compiled these reports on microplastic abundance in the natural aquatic environment. Our results indicate that microplastics are more abundant in sediments than in water, mussels, and fish. There is a significant correlation between mussels and sediments, but not between water and mussels or between water/sediment and fish. Bioaccumulation of microplastics appears to occur through water, but the route of biomagnification is unclear. More sound evidence is required to fully understand the biomagnification of microplastics in aquatic environments.