微塑料是指粒径小于5 mm的塑料颗粒，广泛存在于水体、土壤和大气中，近年来更是在人体内被相继检出，其暴露产生的人体健康风险引起全球广泛关注。但当前微塑料分析方法不统一导致的不同研究结果之间难以比较，制约了对人体微塑料的污染特征和暴露风险的科学认知，使得现有研究结果难以支撑微塑料健康风险评估的需求。因此，系统调查人体微塑料的暴露水平，揭示微塑料来源，丰富微塑料污染的科学数据，对支撑微塑料污染的健康风险评估和加强新污染物治理具有重要现实意义。本研究建立了激光红外光谱（LDIR）和热脱附–气相色谱–质谱联用（Py-TD-GC/MS）微塑料分析方法，调查了南方某城市人群组织、排泄物、空气、饮用水和膳食中微塑料污染特征，探讨了人体微塑料来源、分布和排出特征，提出了人体微塑料污染防治建议，主要结论如下：

人体肺组织中的微塑料丰度最高（14.19 ± 14.57 n/g，N = 14），其次是小肠（9.45 ± 13.13 n/g，N = 10）、大肠（7.91 ± 7.00 n/g，N = 6）、扁桃体（6.03 ± 7.37 n/g，N = 11）和胎盘（2.70 ± 2.65 n/g，N = 17）。在各个组织中，微塑料粒径均主要集中在20–100 μm，聚氯乙烯（polyvinyl chloride，PVC）是最普遍的聚合物类型，碎片是最常见的形态。另外，总体上女性体内微塑料丰度显著高于男性（p < 0.05），这为全面分析人体微塑料污染特征和暴露风险提供了直接证据和基础数据。

南方某城市郊区居民粪便中微塑料水平（11.07 ± 12.23 n/g，N = 28）显著高于农村居民（7.03 ± 11.53 n/g，N = 30）和市区居民（2.60 ± 3.97 n/g，N = 28）（p < 0.05），并且未成年人排泄物中微塑料丰度高于成年人，女性高于男性。PVC、聚丙烯（polypropylene，PP）和聚乙烯（polyethylene，PE）是粪便中最主要的聚合物类型，而PP、PE、PVC和聚对苯二甲酸乙二醇酯（polyethylene glycol terephthalate，PET）是尿液中检出率最高的聚合物，这可能与食品塑料包装、塑料制品和水产品来源的微塑料有关。另外，小粒径微塑料（< 20 μm）质量浓度高于大粒径（> 20 μm），分别占粪便和尿液中微塑料总浓度的90.28%和68.31%。以上结果丰富了对人体微塑料暴露风险的认识。

该城市室外空气、室内降尘、自来水、饮料和膳食中均普遍存在微塑料：空外空气（1.05 ± 0.80 n/m³，N = 21）、室内降尘（506.45 ± 374.45 n/m²/d，N = 36）、自来水（105.39 ± 265.34 n/L，N = 18）、饮料（80.00 ± 52.92 n/L，N = 3）、膳食（64.25 ± 267.08 n/g，N = 22）。虽然不同基质中聚合物组成存在差异，但几乎均以PVC为主。所有微塑料粒径主要集中在20–100 μm，且大多数均呈碎片状。经分析，市区室内空气微塑料的沉降率高于农村和郊区，但郊区自来水微塑料丰度高于农村和市区，塑料包装和食物处理方式可能是造成膳食样品中微塑料污染差异的主要原因。此外，静脉输液治疗也是人体微塑料的潜在直接来源之一。

据估算，一个成年人每天通过室外空气、室内降尘、饮用水和膳食可摄入30,087.54 n或31.26 mg的微塑料，其中膳食是人体微塑料暴露的最主要来源。进入消化系统的微塑料，仅8.0–16.7%被排出体外，83.3–92.0%累积在胃肠道，并可能通过循环系统转移到各个组织或器官。室内空气是呼吸系统微塑料的主要来源，尽管吸入的大部分微塑料被清除，但在肺中的累积量仍达到10,728–11,317 n或34–35 mg，占人体微塑料负荷的66–94%。总体上，成年人微塑料暴露量高于儿童和婴儿，女性体内微塑料污染水平高于男性（血液除外）。利用聚合物单体危害指数（PHI）评估人体组织和排泄物微塑料污染，发现其均处于V级，其中氯乙烯（VC）单体浓度处于0.27–51.13 ppm。为预防微塑料污染健康风险，建议提高塑料回收利用的经济性和质量，开发可持续循环的解决方案，科学管控塑料垃圾丢弃，提高公众意识、减少塑料摄取。

综上，本文基于对人体组织、排泄物、饮食和空气中微塑料污染的系统调查，初步揭示了人体微塑料污染特征，探究了人体微塑料的潜在来源，提出了微塑料污染预防建议，为微塑料污染健康风险评估提供了一手资料，为从源头预防微塑料污染提供了科学数据并奠定了方法学基础和理论依据。

Microplastics are the plastic particles of smaller than 5 mm in size, which distribute widely in marine, terrestrial, and atmosphere environments. Recently, microplastics are detected in humans, which has raised global concerns regarding the health risks associated with microplastic exposure. However, inconsistent analysis methods hinder the comparison between different studies, limiting the scientific knowledge of pollution characteristics and exposure risks of microplastics in humans, thus the current results are insufficient to support the need for assessing health risk of microplastics. Therefore, a systematic investigation of exposure level of microplastics, revealing the sources of microplastics, and increasing the scientific data on microplastic contamination are of significance for supporting the health risk assessment of microplastic pollution and strengthening the treatment of emerging pollutants. Based on this, this study established the analysis method applied to laser direct infrared (LDIR) and pyrolysis thermal desorption-gas chromatography-mass spectrometry combined pyrolysis using a tubular furnace (Py-TD-GC/MS). Further, they were used to explore the microplastic characteristics in human tissues, excretion, air, drinking water, and diet from a southern city, which indicated the characteristics of source, distribution, and excretion of microplastics in humans, and proposed the suggestion of prevention and control of microplastics polluted to humans. The main conclusions are as follows:

The highest abundance of microplastics was detected in lung tissue with an average of 14.19 ± 14.57 particles/g (N = 14), followed by small intestine (9.45 ± 13.13 particles/g, N =10), large intestine (7.91 ± 7.00 particles/g, N =6), tonsil (6.03 ± 7.37 particles/g, N =11), and placenta (2.70 ± 2.65 particles/g, N =17). Microplastics 20–100 μm were concentrated in these tissues, with polyvinyl chloride (PVC) being the dominant polymer and fragment being the main shape. Moreover, the abundance of microplastics was also significantly higher in females than that in males (p < 0.05). This study provides evidence and empirical data regarding the pollution characteristics and exposure risks of microplastics in humans.

Microplastic level in populations lived in suburban areas from a sounthern city (11.07 ± 12.23 n/g, N = 28) was significantly higher than those in rural (7.03 ± 11.53 n/g, N = 30) and urban areas (2.60 ± 3.97 n/g, N = 28, p < 0.05). The abundance of microplastics in the excretion of minors was higher than that of adults, and microplastic abundance in the feces of females was higher than that of males. PVC, polypropylene (PP), and polyethylene (PE) were the most pervasive polymers in feces, and PP, PE, PVC, and polyethylene terephthalate (PET) were the most frequently detected polymers in urine. This might be related to microplastics released by plastic packaged food, plastic products, and aquatic products. Moreover, the mass concentration of small-sized microplastics (< 20 μm) was significantly higher than large-sized microplastics (> 20 μm), accounting for 90.28% and 68.31% in feces and urine. This improved the understanding of exposure risks of microplastics in humans.

Microplastics were widely detected in outdoor air, indoor fallout, tap water, beverage, and diets in this city, that is, 1.05 ± 0.80 n/m³ (N = 21) in outdoor air, 506.45 ± 374.45 n/m²/d (N = 36) in indoor fallout, 105.39 ± 265.34 n/L (N = 18) in tap water, 80.00 ± 52.92 n/L (N = 3) in beverage, and 64.25 ± 267.08 n/g (N = 22) in diets. Although there were differences in polymer compositions in different matrix, almost all are mainly PVC. All microplastics were mainly concentrated in 20–100 μm, with fragments being the majority. Through analysis, the deposition rate of indoor fallout microplastics in urban areas was higher than that in rural and suburban areas, while the abundance of microplastics in suburban tap water was higher than that in rural and urban areas. Plastic packages and food processing might be the primary reasons of the differences in the occurrence of diet microplastics. Additionally, infusion solution was one of the direct pathways of microplastics in humans.

It was estimated, that, an adult could consume microplastics of 30,087.54 n/d or 31.26 mg/d through outdoor air, indoor dust, drinking water, and diet, with diet being the main source of microplastic exposure to human body. After plastic particles entering the digestive system, only 8.0–16.7% could be excreted from the body, while 83.3–92.0% of microplastics could be accumulated in the gastrointestinal tract. These microplastics might be transported to the circulatory system and then transfer to various tissues or organs. Indoor fallout was the primary source of microplastics in the respiratory system. Although most inhaled plastic particles were eliminated, the accumulation in the lungs could reach 10,728–11,317 n or 34-35 mg, accounting for 66-94% of the microplastic load in humans. Totally, microplastic level was higher in adults than that in children and infants, and females showed higher microplastic level than males (excluding blood). Both human tissues and excreta exhibited a Level V Polymer Toxicity Index (PHI), in which the concentration of vinyl chloride (VC) monomer was within the range of 0.27–51.13 ppm. To prevent the health risks posed by microplastics, this study suggested improving the economics and quality of plastic recycling, developing sustainable circular solutions, curbing scientifically plastic waste and littering, and raising public awareness to reduce plastic intake.

In summary, this study investigated systematically the pollution characteristics of microplastics in human tissues, excreta, diets, and air, preliminary revealed the characteristics of microplastic polluted to humans, explored the potential sources of human microplastics, and proposed prevention suggestions for microplastic pollution. This provides first-hand information for assessing health risks of microplastic pollution, scientific data for preventing microplastic pollution from the sources, and lays a methodological and theoretical foundation.