Since its birth, the plastic industry has developed rapidly and the market share has increased rapidly^[3]By 2019, the global plastic production has reached 400 million tons^[4]（Figure 1A）. With the development of economy and the improvement of consumption level, the plastic production will have a further growth trend in the future. According to the data provided by plasticsceurope, by 2022, the industrial scale of plastic raw materials and plastic products in Europe had still increased by about 20% compared with 2015^[5]It is estimated that the global annual plastic production will exceed 1.1 billion tons in 2050.

There are many kinds of traditional plastics, such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyurethane (PUR) and polyethylene terephthalate (PET), which are widely used due to their different properties. It can be divided into fiber type and non fiber type according to the purpose, and there are significant differences between them in the application field and production process. In 2019, PE (28%), PP (19%) and PVC (13%) ranked the top three in terms of the proportion of non fiber plastics output, while pet, PS and pur accounted for no more than 10%^[5] （Figure 1B）; Polyester fiber accounts for 70% of the total output of fiber plastics, and pet contributes significantly^[6]About 42% of non fiber plastics are used for packaging, which is the largest plastic consumption field. PE, PP and pet are the mainstream raw materials. PET material has the advantages of light weight, transparency, impact resistance and chemical corrosion resistance, which can effectively protect the quality of liquid products and improve the safety^[7-8]So it is popular. The construction and construction industry is the second largest consumer sector, accounting for 69% of the total PVC production and 19% of non fiber plastics^[9]（Table 1）. Due to its strong corrosion resistance, convenient installation and long service life, PVC pipes have become the preferred materials for water supply and drainage systems in the construction field^[10]。

The plastic industry plays a significant role in promoting the global economy. Plastic production and processing enterprises provide a large number of employment opportunities, from raw material production to product manufacturing, and then to recycling, involving many links and industries. Moreover, plastic products have low cost and superior performance, which are widely used in various products, driving production demand, improving production efficiency and reducing manufacturing costs. Due to the wide application fields and huge economic effects of plastics, it has become indispensable in modern industry and daily life.

Plastic products may cause pollution in production, use, recycling and other links, and then induce major global environmental problems^[11]Due to the imperfect recycling system, high recycling costs and lack of public awareness of environmental protection, a large number of waste plastics have not been effectively recycled^[12-13]According to the summary statistics of China's plastic products industry, the output will be 74.885 million tons in 2023, while the recycling of waste plastics will only be 19million tons^[14]Globally, only about 18% of plastic waste is recycled, 24% is incinerated, and the remaining 58% is landfilled or entered the natural environment^[6]For example, the landfill rate of waste plastics in the United States exceeds 75%, accounting for 19% of all municipal solid waste. According to the current growth rate, the cumulative amount of plastic waste landfilled and/or entering the natural environment worldwide is expected to reach nearly 120million tons by 2050^[15]。

Plastics are difficult to degrade in the natural environment. It usually takes hundreds of years or even longer to completely decompose. During this period, harmful substances will be continuously released, threatening the safety of the ecosystem^[12,16]Among them, microplastics (MPS) pollution is a hot issue in the field of ecological environment and public health in recent years. MPs refers to plastic particles, fibers and fragments with a particle size of<5 mm, which are released through the decomposition of large plastic products, industrial and personal care products, etc^[17]Access to the environment. MPs not only has a negative impact on the ecosystem, but also may pose a potential threat to human health^[18-19]The latest research shows that MPs entering the human body will accumulate in the arteries, which may increase the risk of heart disease, stroke and other diseases^[20]。

In the face of major environmental and health problems such as "white pollution" and MPs infringement, the idea of using biodegradable plastics (BPS) instead of traditional plastics to alleviate or even solve plastic pollution has been widely spread^[21]In theory, BPS can be rapidly decomposed into harmless substances (such as water, carbon dioxide and biomass) under the action of microorganisms in the natural environment, so as to reduce the pollution of discharged plastics to the environment^[22]。

The main raw materials of BPS include lignin, cellulose, starch and bioethanol, which are renewable resources, reducing the dependence on oil resources, and then promoting resource recycling and sustainable utilization. The main types of BPS include bio based polylactic acid (PLA), polyhydroxyalkanoate (PHA) and starch mixtures, as well as petroleum based polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL) and polybutylene succinate (PBS)^[5]PLA PHA、 BPS, including starch mixtures, accounted for 53.8% of the global production of bio based plastics in 2023 (about 1.14 million tons)^[23]（Figure 2）. BPS has been widely used in many key areas. In the field of food packaging, BPS can be made into straw, disposable tableware, paper cup, etc. In agricultural production, the main applications of BPS include plastic film, compost bag, pesticide slow-release carrier, etc. In the field of medical materials and devices, BPS (such as PLA) are widely used in the production of surgical sutures, artificial bones, artificial skin, medical stents, orthopedic needles, stents, wound dressings, etc. due to their excellent biocompatibility, which promote the progress of medical technology and improve the safety of the treatment process. It is estimated that by 2028, the global production of BPS will reach about 4.61 million tons^[24]。

In 2020, the national development and Reform Commission and the Ministry of ecological environment issued the opinions on Further Strengthening the treatment of plastic pollution, further prohibiting and restricting the production, sale and use of plastic products, promoting alternative products such as biodegradable plastic bags, and ushering in new opportunities for the development of biodegradable materials. In recent years, policies such as the "14th five year plan" for green industrial development, the "14th five year plan" for raw material industry development, and the "three year action plan for accelerating the innovation and development of non grain bio based materials" have been issued frequently, strongly supporting the high-quality development of biodegradable materials. By 2027, the scale of China's degradable materials industry is expected to reach 32.41 billion yuan, with a year-on-year increase of 19.5%^[25]。

However, there are still some disputes about whether BPS is really green, environmental protection and safety in the academic community. With the increasingly frequent use of BPs, the potential risks caused by biodegradable microplastics (BMPs) and oligomers released from BPS degradation are increasingly serious^[19]The BPS discharged into the natural environment are not degraded rapidly as expected. For example, BPs in the water environment ecosystem may not be completely degraded in a short time, but may produce more BMPs than petroleum based plastics, and the potential harm may also increase^[26]In addition, some BMPs may even act as carbon sources to interfere with the normal metabolic activities of some microbial communities and disrupt the ecological balance^[23]It can be seen that the simple and large-scale promotion and use of BPS can not completely eliminate the pollution of traditional plastics, especially the ecological environment and health risks brought by BMPs. However, the research on the potential hazards of waste BPS and derived BMPs is still in its infancy, especially their migration and transformation behavior in the environment and potential ecological and health effects. Compared with traditional non degradable plastics, BPS has stronger degradability and is easier to decompose into BMPs to a certain extent, but so far there is little in-depth analysis of the temporal and spatial distribution of BMPs in different environmental media and the content of BMPs in different animals and plants. These questions have seriously hindered the development of hazard identification and prevention measures for BPS and its derivative BMPs.

As a substitute for traditional plastics, BPS has made some progress in production and application due to increasing policy support. However, the environmental health risks caused by BPS still need to be further studied and solved to ensure the realization of its goal of real environmental protection and sustainable development in practical application. Therefore, this review will deeply discuss the potential environmental health risks of BPs, especially the analysis methods of BMPs and their occurrence in the environment, analyze their exposure pathways and potential health effects, and prospect the future application trends and challenges of BPs, so as to provide theoretical and technical support for the promotion and application of BPS and risk prevention.

The analysis of refractory MPs in environmental samples generally includes sample preparation and detection analysis^[30]MPs is separated and purified from environmental media such as atmosphere, water, soil and organisms through sample pretreatment, and then its mass concentration or particle size distribution is characterized and counted by different instruments（Figure 3）。

According to the type of polymer and environmental conditions, BMPs formed by BPS may remain in the natural environment for decades. On the one hand, the biodegradation process in the natural environment is slow, on the other hand, BMPs particles are mainly composed of microcrystals, and the crystal structure is not easy to be approached by aging medium, so the biodegradation rate is lower, so it can exist for a long time^[53]These BMPs usually come from agricultural applications and the use of daily products, such as mulching film, packaging materials, catering products, cosmetics and textiles, which bring pollution to the ecosystem. Based on the current limited research on the concentration of BMPs in the environment, these materials are not uncommon in the aquatic environment. PLA, PHA and PBAT were identified in water purification wastewater, sewage sludge and marine sediment samples^[54]The content of PLA is the highest, and the concentration range is 90~180 μ g/g（Table 3）。

Compared with traditional plastics, the degradation of BPS is more susceptible to various factors, and its degradation rate may be accelerated to produce a large number of BMPs^[55]. Lambert and Wagner^[56]The MPS released from four kinds of traditional plastic materials (PP, PE, PS, PET) and biodegradable PLA plastics under UV irradiation at 30 ℃ were studied. It was found that after 112 days, the number of MPS increased in all types of plastics, and the release of micron particles from PS plastic cover and PLA cup increased the most. Wei et al^[53]The degradation processes of biodegradable PBAT and traditional LDPE were compared in different aquatic environments. It was found that PBAT was more likely to produce MPs than LDPE, because in addition to microbial decomposition, ultraviolet degradation, oxidation and erosion also promoted the formation of BMPs. Weinstein et al^[57]The degradability of biodegradable PLA in salt marsh was compared with that of traditional pet, HDPE and PS. after 4 weeks of natural weathering, MPs and biofilm were detected in all plastic types. This shows that there is no significant difference between BPS and traditional plastics in terms of degradation and MPs production under natural conditions. Therefore, the biodegradability of BPS can not eliminate BMPs, but has greater potential for BMPs accumulation.

In addition, due to the degradability of BPs, the impact of BMPs on the ecological environment should be regarded as the dual input of physical and biochemical^[58]For example, BMPs in soil may become the carbon source of microorganisms, affecting the composition and function of soil microorganisms, and the release of BMPs degradation by-products will also have a more far-reaching impact. At present, the research on the environmental behavior of BMPs is not comprehensive, and more experimental data are needed in the future to further explore the environmental occurrence and ecological risk of BPS.

A stable food chain is the key factor to maintain the balance of species in the ecosystem. As the starting point of the food chain, primary producers play a vital role in food supply and ecosystem functions. Studies have found that BMPs and BNPs in the environment will directly or indirectly affect the growth, physiology and development of aquatic or terrestrial primary producers^[23]（Table 4）。

In the aquatic environment, the effects of BMPs on aquatic primary producers are mainly manifested in the growth inhibition of algae, cell structure damage and metabolic disorder, etc^[23]It was found that PLA MPs and PBS MPs could inhibit the growth of microalgae in a wide concentration range (10~1000 mg/L), and the severity of inhibition was positively correlated with the exposure concentration and time. Exposure to higher concentrations of BMPs promotes the production of chlorophyll and extracellular polymeric substances in microalgae, which may be a defense mechanism caused by stress^[63]In another study, Microcystis exposed to 10-200 mg/L PLA MPs showed oxidative damage and changes in cell morphology. With the extension of exposure time, the growth of Microcystis was firstly inhibited, and then promoted^[64]Therefore, BMPs can play a dual role as a potential inorganic carbon source to promote the growth of algae and as a particulate matter to hinder the growth of algae. Cyanobacteria will suffer different degrees of toxic damage when exposed to submicron and nano PCL (polycaprolactone) and its oligomers. When exposed to different fractions or combinations of PCL MPs alone, both organisms showed excessive reactive oxygen species (ROS) production, intracellular pH changes and metabolic activity changes. However, changes in membrane potential and morphological damage were observed only when the combination of PCL NPs and PCL oligomers was exposed^[65]Similarly, Yoshinaga et al^[66]When brown algae were exposed to PCL MPs particles or oligomers, it was found that the plasma membrane damage and energy metabolism disorder were only observed in the oligomer treatment group. Therefore, BMPs with different sizes and polymerization degrees will significantly affect their toxicity levels.

MPs may be ingested by plankton and large marine animals, which will lead to physical blockage and chemical damage^[62]This intake not only reduces their feeding activities, destroys the balance of intestinal microorganisms, but also causes damage to their reproduction, growth and development. The mortality of Daphnia magna exposed to 5 mg/L PLA MPS was significantly increased, and long-term exposure to 1 and 5 mg/L PLA MPs resulted in the reduction of offspring, the change of sex ratio and the increase of abnormal embryos^[67]. viel et al^[68]They paid attention to the effects of PBS, PBSA, PCL, PHB and PLA on marine invertebrates. They found that three kinds of BMPs could affect embryonic development. PHB MPs and PLA MPs destroyed the first mitosis of eggs and led to developmental retardation of other eggs, while PCL MPs led to embryonic malformation. In addition, de Oliveira et al^[69]Zebrafish experiments showed that the accumulation of PLA MPs in larvae was related to the changes of movement and exploration activities and the inhibition of acetylcholinesterase function. Exposure to 100 mg/L PGA MPs and PLA MPs can cause zebrafish growth retardation 24 hours after fertilization, reduce survival rate, affect sleep patterns and induce anxiety like behavior^[70]After the combined exposure of PLA MPs and PBAT MPs, zebrafish showed shallow water behavior, anxiety like reaction and avoidance behavior. BMPs may cause abnormal behavior and neurotoxicity in zebrafish by inducing brain immune dysfunction^[71]The long-term intake of PLA MPs significantly affected the social behavior of juvenile Lateolabrax japonicus, such as decreased motor ability, reduced internal gathering distance and weakened active predator response^[72]BPS can also affect the visual function of zebrafish. After exposure to PLA -, PBS -, PHA - and pbat-mp, the genes related to early visual development of zebrafish juveniles changed^[73]In addition, compared with traditional plastics, some aquatic organisms, such as zebrafish and perch, showed stronger feeding preference for pla-mp^[74]Intestinal injury is another significant effect of BMPs. Duan et al^[75]It was reported that the pla-mp residue in adult zebrafish was higher than that in pet-mp after 90 days of exposure to PLA - or pet-mp. Although the degradation products of PLA can be absorbed by zebrafish as a carbon source, the histological damage caused by pla-mp on fish intestine is more significant. Bao et al^[76]It was also found that compared with the traditional plastic pvc-mp, the intestinal edema of tilapia fed with pla-mp was more obvious, and the intestinal flora was significantly maladjusted.

For the terrestrial environment, agricultural plastic film is an important application scenario of BPs, so the impact of BPS on crops and animals in the terrestrial environment deserves attention. On the one hand, BMPs have adverse effects on primary producers by changing soil properties and ecological functions^[77]For example, BMPs can affect the nitrogen cycle mediated by BMPs by affecting soil microbial community, function and diversity, such as nitrogen fixation process, anaerobic denitrification process, etc., and then affect crop growth. For example, some agricultural film mulching residues can significantly reduce the expression of carbon and nitrogen cycle in soil and affect soil fertility^[78]On the other hand, BMPs may have direct toxic effects on plants. BMPs may induce plant cells to produce reactive oxygen species (ROS) by inducing mechanical damage. The accumulation of these reactive oxygen species may damage the plant cell membrane and other cell structures, thus triggering a series of oxidative stress reactions^[79]. Yang and Gao^[80]The oxidative stress response of rice stems and roots induced by MPS was reported. The genes encoding ammonium and nitrate transporters in rice roots were down regulated during vegetative development and up-regulated during reproductive development in PBAT exposed group. BMPs significantly inhibited the net photosynthetic rate of plants during vegetative period and reduced the expression of light response related genes. In addition, the study focused on the effects of BMPs on crop germination and early growth. For example, compared with PP MPs, PLA MPs and PHB MPs in soil had more significant inhibitory effects on the early root growth of sorghum, Oenanthe javanica and mustard^[81]Degradable mulching film is similar to PS and PE mulching film, which will lead to the decrease of seed germination rate, leaf area and plant height^[82-83]。

Similar to the aquatic environment, BMPs and BNPs in the soil environment may be widely spread through the food chain. Compared with plants and microorganisms, animals, as the main consumers in terrestrial ecosystems, are at greater risk of ingesting more MPs directly or through food chain transfer (intake of foods containing MPs and NPs)^[84]Recently, more and more ecotoxicological evidences show that BMPs have no less toxic effects than traditional MPs, and its safety still needs to be further evaluated（Table 4）。

Earthworm is a common soil invertebrate, which is often used to evaluate the ecological toxicity of environmental pollutants. Ding et al^[85]The effects of PLA -, PC - and PE MPs on the biological toxicity, mortality, avoidance behavior and reproductive response of earthworms were studied. It was found that the concentration of BMPs had a greater impact than the type of plastic. Zhao et al^[86]The different responses of earthworms to PLA -, PVC - and PE MPs in soil environment were studied. It was found that the ecotoxicity of BMPs to earthworms was time-dependent. After 28 days of exposure to 50 g/kg, the earthworm epidermis showed mucosal cavitation, longitudinal muscle disorder and granular lipid deposition. This study also emphasized that BMPs had similar toxicity to traditional MPs. Another study used Drosophila as a model to explore the internalization and related effects of PLA NPs. They found that PLA NPs were enriched by enzyme vesicles and passed through the intestinal membrane, and finally internalized by intestinal cells. Their exposure triggered intestinal damage, oxidative stress, DNA damage and inflammatory reaction^[87]In addition, in the dragonfly larva model, PLA MPs also showed greater toxicity than traditional plastics, causing redox imbalance and neurotoxicity^[88]。

MPs are ubiquitous in the environment and can migrate between different environmental media and enter the human body through the food chain, direct inhalation or skin contact^[89-90]According to the estimation of food consumption, each person may consume 39000-52000 plastic particles per year^[91]A large number of studies have detected MPs in human biological samples (including excreta, body fluids, tissues and organs), which has triggered widespread health concerns^[92]Similarly, with the widespread use of BPs, human beings will inevitably be exposed to BMPs and BNPs.

Although many previous studies have used invertebrates, zebrafish and other low-grade organisms to show that the toxic effects of BMPs are similar to those of traditional plastics, the sensitivity and response patterns of these organisms are significantly different from those of terrestrial mammals, which can not fully and accurately reflect the impact of BMPs on complex biological systems^[93]In order to better understand the potential impact of BMPs on terrestrial mammals and human health, some recent studies have used mammals as models to explore. Our previous work compared the toxicity of irregular PLA - and PVC MPs to growing mice. The results showed that the biological toxicity of PLA MPS was no less than that of PVC MPs, and the effect on lipid metabolism and digestive system was more significant. Specifically, both MPs caused an increase in the level of oxidative stress, changes in the intestinal microbial community, and changes in gene expression in the liver and colon. These findings challenge the biological safety of BPS and BMPs^[94]In another study, male mice were exposed to PLA MPs for 10 consecutive days, which showed liver injury and increased inflammation. This process is mainly due to the inhibition of CYP7A1 enzyme activity by PLA MPs and the activation of fgf-jnk/ERK signaling pathway, which destroys the normal metabolism of bile acids^[95]. Zha et al^[96]The hepatotoxic effects of PLA MPs and PLA NPs from different exposure sources were investigated by using multinomial methods. It was found that food derived and air derived PLA MPs induced hepatotoxicity by interfering with the "gut microbiota liver" axis and the "airway microbiota lung liver" axis, respectively. Specifically, they led to intestinal and pulmonary flora imbalance, intestinal, lung and serum metabolic changes, and liver transcriptome changes.

As a kind of biodegradable polyester, the transformation process of BPs in the intestine and the toxic effects caused by degradation products have attracted much attention. Wang et al^[19]It is reported that PLA MPs can be degraded by lipase in the gastrointestinal tract and produce excessive PLA NPs. These nanoparticles are formed by hydrophobically driven oligomer self aggregation, and after exposure, oligomers and their related nanoparticles will bioaccumulate in different organs (including liver, intestine and brain) and cause intestinal injury and inflammation. Liang et al^[97]A 28 day oral gavage study in mice showed that the incomplete degradation of PLA MPs in the gastrointestinal tract would increase its bioavailability and toxicity, thereby aggravating nerve injury. The mechanism of neurotoxicity induced by these MPs is similar to that observed in the pathology of Parkinson's disease, which is characterized by mitochondrial calcium overload in the midbrain region. In the past, people mainly focused on BPS itself, and the above findings suggest that BPs degradation intermediates may also be potential contributors to polymer toxicity. Environmental friendly biopolymers are usually composed of endogenous monomers, which leads to the possibility that their oligomers may have the ability to interfere with the metabolism of organisms and cause a variety of toxic effects^[18]The structure of oligomers is complex, the physical and chemical properties are greatly different, and the types and number of oligomers are far more than MPs itself. The current understanding of oligomers is only the tip of the iceberg. Therefore, the absorption, distribution, metabolism, excretion and toxicity (ADMET) of BPS oligomers should be paid special attention and studied in depth in the future.

Compared with mammalian model, in vitro cell model provides a rapid, economic and easy to control method, which can carry out multi-endpoint toxicity assessment and simplify the exploration of toxicity mechanism to a certain extent^[98]These cell models will not only help researchers quickly predict and evaluate the potential impact of these new materials on human health, but also help to formulate relevant safety standards and regulatory policies（Table 5）. Banaei et al^[99]Using Caco-2 and HT29 colon adenocarcinoma cell lines, the behavior of PLA NPs released from tea bags in intestinal epithelium was studied. It was found that these particles could be internalized and absorbed by intestinal cells. Garc í a- Rodr í Guez et al^[100]Using the in vitro bronchial epithelial model Calu-3 cell line, it was found that PLA NPs were easily internalized by the barrier under the condition of gas-liquid interface exposure, resulting in increased barrier permeability and mucus secretion, and long-term exposure would lead to significant genetic toxicity and immune response. In addition, as part of the innate immune system, macrophages play an important role in the defense of exogenous particles. Studies have found that PLA NPs can reduce the phagocytic activity of macrophages and increase the secretion of proinflammatory factors represented by TNF - α^[101]， PLA degradation intermediate oligomer has stronger pro-inflammatory effect than MPs itself^[19]In terms of neurotoxicity, Yoshinaga et al^[66]It was found that compared with PCL MPs itself, its oligomer (tetramer) and monomer had stronger toxicity to neurons differentiated from PC12 cells, resulting in decreased cell viability, impaired mitochondrial function and morphological changes of neurons. In another high-throughput screening study in vitro, the methanol extract of PCL activated five toxicity endpoints, including pregnane X receptor (pxr/pxre) and peroxisome proliferator activated receptor γ (PPAR γ/ppre). Studies have shown that this toxicity may be caused by oligomers and nanoparticles released by PCL^[102]This kind of multi endpoint in vitro reporting bioassay combined with non targeted chemical analysis has significant application value in evaluating the safety of BPs, especially for screening the key toxic components in plastic related chemical mixtures. Researchers have used yeast and luminescent bacteria^[103]Fish cell line^[104]And mammalian cell lines^[105]The high-throughput toxicity evaluation of BPS consumer product extract was carried out in vitro. The results showed that BPs showed non negligible toxicity, which was mainly caused by the degradation of BMPs BNPs、 Caused by oligomers and additives. Previously, people mainly focused on the impact of BMPs, but more and more studies have shown that BMPs themselves and the by-products produced in their degradation process are different in toxicity. Future studies should further clarify the main sources and mechanisms of these "plastic toxicity".

Although there are direct evidences showing the distribution and content of BMPs and BNPs in human tissues, the latest epidemiological studies show that the content of MPs in human body is closely related to cardiovascular and cerebrovascular diseases and intestinal inflammation, which are consistent with the results of animal and cell experiments. Different from traditional plastics, BPS are easier to degrade in vivo, producing smaller BNPs and oligomers, which are easier to enter the circulatory system through the gastrointestinal tract, penetrate the biological barrier and enter the cells, which may lead to more serious health risks such as intestinal inflammation. In addition, during the degradation process, the additives contained in the polymer are more likely to be released, which together with the polymer have toxic effects on the body. On the other hand, the surface of BMPs and BNPs particles is more rough, and contains rich oxygen-containing functional groups and hydrogen bonds. It is speculated that these characteristics make it easier to combine with specific proteins in body fluid to form a "protein crown", which will give new biological characteristics to nanoparticles, and then affect the interaction mode, toxic effect and potential mechanism between plastic particles and cells^[106]。

Therefore, waste BPS and BMPs are not only emerging environmental issues, but also an important public health issue. In the future, we need to pay special attention to and in-depth study the impact on the ecological environment and human health. In particular, BMPs may have different mechanisms for biological interference at different trophic levels. In addition to analyzing the environmental and health effects caused by BMPs, future research should also deeply analyze the toxic mechanism, providing new ideas and directions for the research and development of BPS pollution control measures in the future.

The main reason why BPS can be widely used is that its core concept is biodegradable and environmentally friendly. When countries popularize and use BPs, they usually focus on its advantages, but tend to ignore the disadvantages and potential hazards of BPS. Therefore, the public will think that BPs can solve the pollution and harm caused by traditional plastics once and for all. More seriously, it will further deepen people's cognitive bias and firmly believe that BPs is environmentally friendly and can be directly discharged without any treatment and disposal, resulting in a large number of BPS directly and disorderly discharged into the environment, thereby increasing the content of BMPs in the environment.

Therefore, before identifying, evaluating and disposing the potential hazards of BPS and BMPs in the future, it is necessary to help people fully understand the advantages and potential hazards of BPs, especially the complete environmental behavior of discharged bps. Only by correctly recognizing the potential harm of excessive emission of BPs, can we reduce the emission of BPS from the source and promote the true environmental friendliness of BPS.

Similar to traditional refractory MPs, BMPs with different concentrations and types have been detected in typical environmental media such as water, soil and atmosphere. However, there is still a lack of reliable technology to accurately identify the internal laws of BMPs' environmental behavior. The current identification technology of BMPs comes from traditional refractory MPs, and has not formed a set of technical method system suitable for BMPs identification. In the traditional pretreatment process, the use of strong acids and bases may degrade BMPs too quickly to a certain extent, thus underestimating the amount of BMPs in real environmental media and biological samples. On the other hand, BMPs are usually blends, which directly leads to the difficulty of obtaining test standards. Therefore, compared with traditional MPs, the analysis and detection process of BMPs will be more complex. Based on the existing micro Raman spectroscopy, micro infrared spectroscopy, chromatography-mass spectrometry, how to quickly and accurately identify and quantify the types and contents of BMPs is still one of the main challenges in the current and future BMPs related research.

BMPs in environmental media can be ingested by animals and humans through mouth (drinking water, diet) and respiration. In addition, more and more BPS are used in the field of food processing and packaging, indicating that the type and content of BMPs wrongly ingested into the body will gradually increase in the future, but so far, the interpretation of the migration and transformation of different types of BMPs in the body is still limited. In addition to the above sample pretreatment methods and the qualitative and quantitative methods in vivo, BMPs may be partially degraded in vivo, which further increases the difficulty of qualitative and quantitative analysis in vivo. Nevertheless, it is an important premise to understand the toxic effect and potential mechanism of BMPs by clarifying the absorption, distribution, metabolism and excretion (ADME) of BMPs in vivo. Therefore, future research needs to further develop methods to explore the migration and transformation of BMPs in vivo, and accurately identify the ADME process of BMPs with different properties in vivo.

More importantly, BMPs have non negligible toxicity in vivo. Compared with the traditional material MPs, BMPs represented by PLA can degrade into smaller particle size BMPs or even BNPs in vivo, leading to more serious toxic effects. However, at present, the research on the health effects of BMPs in vivo is mainly focused on a few kinds of materials such as PLA and PBAT, and there is little toxicity assessment on other BPS (such as starch based and starch based PLA blend BMPs) produced and used in large quantities. In addition, in the above-mentioned in vivo and in vitro exposure experiments, the exposure concentration of BMPs was higher than the environmental background concentration and the exposure period was shorter, which was inconsistent with the actual situation that people were exposed to low concentrations of BMPs for a long time. Therefore, in the future, the health risk assessment of BMPs in vivo should not only give priority to the types with large production and wide range of use, but also fully consider the background concentration and exposure cycle in the actual environment, and strive to truly restore and identify the long-term health hazards of typical BMPs in vivo.

On the other hand, the toxicity mechanism of BMPs is still in the black box mode. As a typical particulate matter, the toxicity of MPS not only depends on its physical properties (particle size, shape, surface properties, aging degree, etc.), but also is closely related to its chemical composition. In addition, different kinds of additives added in the production process of BMPs will be absorbed into the body with BMPs, further increasing the complexity of the toxicity mechanism of BMPs in vivo. Therefore, more studies in the future need to focus on how to clarify the toxicity mechanism of BMPs with different characteristics in vivo, provide basic data for the control of BPs, and provide available biomarkers for the prevention of BMPs hazards.

The promotion of BPS has reached major global consensus. Therefore, in the process of controlling and processing BPS and BMPs in the future, governments and scientists of various countries also need to strengthen exchanges and cooperation. When developing relevant management and control methods and governance standards, it is necessary to have a global perspective and consider local government policies and economic background. At the same time, the suggestions of local residents and enterprises shall be actively considered.

To sum up, this paper reviews the potential environmental health risks of BPs in the practical application process from the perspectives of BPS application background and current situation, the occurrence and analysis methods of BMPs produced in the degradation process in the environment, and potential toxicity. On this basis, it further puts forward relevant research deficiencies and future priority development direction, in order to provide theoretical basis and technical support for the future large-scale promotion and use of BPS and reducing the corresponding environmental health risks.