[Human Accumulation and Toxic Effects of Microplastics：A Critical Review].

The effect of microplastics on the ecological environment and human health has become a topical issue， and research on the risks and harmful effects of MPs on human health in particular has attracted widespread attention. Due to the characteristics of small size， low degradability， and easy migration， MPs continuously migrate from the environment to the human body， and their main exposure pathways are oral ingestion， inhalation， and dermal contact， with the main exposure media being food， drinking water， dust， personal care products， etc. MPs have been detected in organs， fluids， and excreta of digestive， respiratory， cardiovascular， reproductive systems， etc. The abundance range of MPs in the human body is 0-1 206.94 particles per gram. After entering the human body， MPs can cause cytotoxicity， mitochondrial toxicity， DNA damage， cell membrane damage， and other effects on human cells and organs， leading to serious consequences such as local inflammation， ecological imbalance， metabolic disorders， etc.， in various systems. Owing to their small specific surface area， they can also adsorb pollutants such as heavy metals， organic pollutants， antibiotics， pathogens， and harmful microorganisms， causing combined toxicity and immunotoxicity. In the end， we highlighted general deficiencies in existing studies and provided directions for future research on the influence of MPs on human health.

Heavy metal(loid)s in agriculture soils, rice, and wheat across China: Status assessment and spatiotemporal analysis.

Heavy metal(loid)s (HMs) accumulation in agricultural soils, rice, and wheat is of particular concern in China, while the status and spatio-temporal distribution of HMs in the soil-crops system have been rarely reported at the national scale. This study aimed to summarize the overall pollution status, spatiotemporal patterns, and drivers of HMs in agricultural soil, rice, and wheat nationwide. The metal-polluted data from 1030 agricultural soils, rice, and wheat in China were collected from the literature published from 2000 to 2022. The results showed that Cd was the most prevailing contaminant in soils based on its spatiotemporal distribution and accumulation. The pollution cases and severe pollution percentage of Cd (103 %) and Hg (128 %) show an increasing trend pattern. Mining activities are the main anthropogenic sources of agricultural soil HMs in China. Cd and Pb had the highest exceedance rate in rice (33.5 and 32.2 %) and wheat (25.8 and 30.3 %). The rice from Hunan, Fujian, and Guangxi showed the highest average concentration of Cd and Pb, respectively, while wheat samples from Hubei had the greatest exceedance rate of Pb. Besides, HMs in crops was not usually corresponding to soil HMs but increased gradually from north to south areas. Several mitigation strategies and accurate health risk assessments model of HMs based on bioavailability were also proposed and recommended. Collectively, this review provides valuable information to improve the management of farmland nationwide, optimize the accurate risk assessment, and reduce HMs pollution.

Heavy metal(loid)s in agricultural soil from main grain production regions of China: Bioaccessibility and health risks to humans.

Unintentional ingestion of metal-contaminated soils may pose a great threat to human health. To accurately evaluate the health risks of heavy metal(loid)s in soils, their bioaccessibility has been widely determined by in vitro assays and increasingly employed to optimize the assessment parameters. Given that, using meta-analysis, we analyzed the literature on farmland heavy metal(loid)s (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in Chinese main grain production regions, and collected their total and bioaccessibility data to accurately assess their human health risks. Monte Carlo simulation was used to reduce the uncertainty in metal concentration, intake rate, toxicity coefficient, and body weight. We found that the mean concentration (0.47 mg/kg) and geological accumulation index (Igeo, 0-5.24) of Cd were the priority position of controlling metals. Moreover, children are more vulnerable to carcinogenic risks than adults. Soil mineralogy, physicochemical properties, Fe, and the types of in vitro assays are the influencing factors of bioaccessibility discrepancy. Furthermore, appropriate bioaccessibility determination methods can be adapted according to the differences in ecological receptors for the risk assessment, like developing a "personalized assessment" scheme for polluted farmland soil management. Collectively, bioaccessibility-based models may provide an accurate and effective approach to human health risk assessment.

The oral bioaccessibility and gingival cytotoxicity of metal(loid)s in wild vegetables from mining areas: Implication for human oral health.

Background: Heavy metal(loid)s are frequently detected in vegetables posing potential human health risks, especially for those grown around mining areas. However, the oral bioaccessibility and gingival cytotoxicity of heavy metals in wild vegetables remain unclear. Methods: In this study, we assessed the total and bioaccessible Cr, As, Cd, Pb, and Ni in four wild vegetables from mining areas in Southwest China. In addition, the cytotoxicity and underlying mechanisms of vegetable saliva extracts on human gingival epithelial cells (HGEC) were studied. Results: The Plantago asiatica L. (PAL) showed the highest bioaccessible Cr, As, Cd, and Pb, while the greatest bioaccessible Ni was in Taraxacum mongolicum (TMM). The Pteridium aquilinum (PAM), Chenopodium album L. (CAL), and TMM extracts decreased cell viability, induced apoptosis, caused DNA damage, and disrupted associated gene expressions. However, PAL extracts which have the highest bioaccessible heavy metals did not present adverse effects on HGEC, which may be due to its inhibition of apoptosis by upregulating p53 and Bcl-2. Conclusion: Our results indicated that polluted vegetable intake caused toxic effects on human gingiva. The heavy metals in vegetables were not positively related to human health risks. Collectively, both bioaccessibility and toxic data should be considered for accurate risk assessment.

Removal of Cr (VI) by Biochar Derived from Six Kinds of Garden Wastes: Isotherms and Kinetics.

Garden waste is one of the main components of urban solid waste which affects the urban environment. In this study, garden waste of Morus alba L. (SS), Ulmus pumila L. (BY), Salix matsudana Koidz (LS), Populus tomentosa (YS), Sophora japonica Linn (GH) and Platycladus orientalis (L.) Franco (CB) was pyrolyzed at 300 °C, 500 °C, 700 °C to obtain different types of biochar, coded as SSB300, SSB500, SSB700, BYB300, etc., which were tested for their Cr (VI) adsorption capacity. The results demonstrated that the removal efficiency of Cr by biochar pyrolyzed from multiple raw materials at different temperatures was variable, and the pH had a great influence on the adsorption capacity and removal efficiency. GHB700 had the best removal efficiency (89.44%) at a pH of 2 of the solution containing Cr (VI). The pseudo second-order kinetics model showed that Cr (VI) adsorption by biochar was chemisorption. The Langmuir model showed that the adsorption capacity of SSB300 was the largest (51.39 mg·g-1), BYB500 was 40.91 mg·g-1, GHB700, CBB700, LSB700, YSB700 were 36.85 mg·g-1, 36.54 mg·g-1, 34.53 mg·g-1 and 32.66 mg·g-1, respectively. This research, for the first time, used a variety of garden wastes to prepare biochar, and explored the corresponding raw material and pyrolysis temperature for the treatment of Cr (VI). It is hoped to provide a theoretical basis for the research and utilization of garden wastes and the production and application of biochar.

Mechanisms of Cd and Cu induced toxicity in human gastric epithelial cells: Oxidative stress, cell cycle arrest and apoptosis.

Cadmium (Cd) and copper (Cu) are widely present in foods. However, their adverse effects on human gastric epithelium are not fully understood. Here, human gastric epithelial cells (SGC-7901) were employed to study the toxicity and associated mechanisms of Cd + Cu co-exposure. Their effects on cell viability, morphology, oxidative damage, cell cycle, apoptosis, and the mRNA levels of antioxidases and cell cycle regulatory genes were investigated. Co-exposure to Cd (5 µM)/Cu (10 µM) induced >40% cell viability loss, whereas little effect on cell viability at <10 µM Cd or 40 µM Cu. Compared to individual exposure, co-exposure induced greater oxidative damage by elevating ROS (3.5 folds), malondialdehyde (2.3 folds) and expression of SOD1 and HO-1 besides inhibiting CAT, GPX1 and Nrf2. A marked S cell-cycle arrest was observed in co-exposure, evidenced by more cells staying in the S phase (36%), up-regulation of cyclins-dependent kinase (CDK4) and CDKs inhibitor (p21) and down-regulation of CDK2, CDK6 and p27. Furthermore, higher apoptosis (22%) with floated and round cells occurred in co-exposure group. Our data implicate the cytotoxicity of Cd + Cu co-exposure was higher than individual exposure, and individual assessment would underestimate their potential health risk. Oxidative stress and cell cycle arrest possibly played a role in Cd + Cu induced toxicity and apoptosis in SGC-7901 cells. Our data suggest the importance to reduce Cd in foods to decrease its adverse impacts on human digestive system.