Plastic particles smaller than 1 μm are considered to be highly dangerous pollutants due to their ability to penetrate living cells. Model experiments on the toxicity of plastics should be correlated with actual concentrations of plastics in natural water. We simulated the natural destruction of polystyrene, polyvinyl chloride, and poly(methyl methacrylate) in experiments on the abrasion of plastics with small stones. The plastics were dyed in mass with a fluorescent dye, which made it possible to distinguish plastic particles from stone fragments. We found that less than 1% of polystyrene and polyvinyl chloride were converted to submicron size particles. In the case of more rigid poly(methyl methacrylate), the fraction of such particles reaches 11%. The concentration of particles with a diameter less than 1 μm in the model experiments was from 0.7 (polystyrene) to 13 mg/L (poly(methyl methacrylate)), and when transferring the obtained data to real reservoirs, these values should be reduced by several orders of magnitude. These data explain the difficulties associated with the search for nanoplastics in natural waters. The toxicity of such particles to hydrobionts in model experiments was detected for concentrations greater than 1 mg/L, which is unrealistic in nature. Detectable and toxic amounts of nano- and submicron plastic particles in living organisms can be expected only in the case of filter-feeding organisms, such as molluscs, krill, sponges, etc.

Short-chain chlorinated paraffins (SCCPs) are persistent organic pollutants which are toxic to human. Median-chain chlorinated paraffins (MCCPs) have similar toxicity to SCCPs. The productions of chlorinated paraffins (CPs) in China were 1 million tons in 2013 and remained high after that, which may lead to high risks for human exposure to CPs. To investigate temporal trends and health risks of SCCPs and MCCPs in breast milk in China, samples (n = 2020) were collected from urban and rural areas of 11 Chinese provinces in 2017 and mixed into 42 pooled samples. SCCPs and MCCPs were analyzed by two-dimensional gas chromatography with electron-capture negative-ionization mass spectrometry (GC × GC-ECNI-MS). The MCCP concentrations (median (range)) were 472 (94–1714) and 567 (211–1089) ng g⁻¹ lipid in urban and rural areas, respectively, which showed continuously rapidly increasing during 2007–2017. The SCCP concentrations (median (range)) were 393 (131–808) and 525 (139–1543) ng g⁻¹ lipid in urban and rural areas, respectively. The results showed SCCP levels decreased in urban areas between 2007 and 2017. Significant increases in MCCP/SCCP ratios might arise from extensive manufacturing and use of MCCPs. The median estimated dietary intake via breast milk in urban and rural samples were 1230 and 2510 ng kg⁻¹ d⁻¹, respectively, for SCCPs and 2150 and 1890 ng kg⁻¹ d⁻¹, respectively, for MCCPs. Preliminarily risk assessment showed that SCCPs posed a significant health risk to infants via breastfeeding. The high MCCP levels should also be of concern because of continuous growth and negative effect on infants. Correspondence analysis indicated congeners with higher carbon and chlorine numbers in dietary tend to accumulate in breast milk.

Insecticide resistance is one of the major obstacles for controlling agricultural pests. There have been a lot of studies on insecticides stimulating the development of insect resistance. Herbicides account for the largest sector in the agrochemical market and are often co-applied with insecticides to control insect pests and weeds in the same cropland ecosystem. However, whether and how herbicides exposure will affect insecticide resistance in insect pests is largely unexplored. Here we reported that after exposure to herbicide butachlor, the lepidopteran Spodoptera litura larvae reduced susceptibility to the insecticide chlorpyrifos. Docking simulation studies suggested that general odorant-binding protein 2 (GOBP2) could bind to butachlor with high binding affinity, and silencing SlGOBP2 by RNA interference (RNAi) decreased larval tolerance to chlorpyrifos. Butachlor exposure induced ecdysone biosynthesis, whose function on increasing chlorpyrifos tolerance was supported in synergism experiments and confirmed by silencing the key gene (SlCYP307A1) for ecdysone synthesis. Butachlor exposure also activated the expression of detoxification enzyme genes. Silencing the genes with the highest herbicide-induced expression among the three detoxification enzyme genes led to increased larval susceptibility to chlorpyrifos. Collectively, we proposed a new mechanism that olfactory recognition of herbicides by GOBP2 triggers insect hormone biosynthesis and leads to high metabolic tolerance against insecticides. These findings provide valuable information for the dissection of mechanisms of herbicide-induced resistance to insecticides and also supplements the development of reduced-risk strategies for pest control.

The present research used zebrafish (5–28 days post-fertilization; dpf) as a model organism to investigate the effects of chronic exposure to environmentally relevant sub-lethal concentrations of waterborne (261 μg/L) and dietary zinc (Zn) (1500 mg Zn/kg dw), either independently or simultaneously, during development. The results showed that whole body contents of Zn were increased in all Zn treatment groups, with the highest accumulation of Zn observed in larvae simultaneously exposed to elevated waterborne and dietary Zn. In addition, exposure to elevated levels of Zn, either through the water or the diet, led to a decrease in whole body calcium (Ca) contents at 28 dpf. The findings also suggested that exposure to elevated levels of Zn resulted in a significant reduction in whole body manganese (Mn) contents. More importantly, the magnitude of decrease in Mn contents by Zn exposure was markedly higher than that in Ca and appeared to mirror the increases in whole body Zn accumulation. These results indicate that Mn regulation is more sensitive than Ca to disruption by Zn exposure in developing fish. Further examination of the Zrt-Irt-Like Protein (ZIP) family of transporters using droplet digital PCR technologies revealed that several zip transporters exhibited temporal and exposure route-specific changes following Zn exposure. In particular, the level of zip4 was influenced by Zn exposure regardless of the exposure routes, while changes in zip7 and zip8 levels were predominantly driven by waterborne exposure. Overall, our findings demonstrated that zebrafish during the developmental periods are sensitive to elevated levels of Zn seen in the environment, particularly following co-exposures to waterborne and dietary Zn. Future toxicological assessment of elevated Zn exposure should consider both the exposure routes and the life stages of fish.

Residential greenspace quality may be more important for people's mental health than the quantity of greenspace. Existing literature mainly focuses on greenspace quantity and is limited to exposure metrics based on an over-head perspective (i.e., remote sensing data). Thus, whether greenspace quantity and quality influence mental health through different mechanisms remains unclear. To compare the mechanisms through which greenspace quantity and quality influence mental health, we used both remote sensing and street view data. Questionnaire data from 1003 participants in Guangzhou, China were analysed cross-sectionally. Mental health was assessed through the World Health Organization Well-Being Index (WHO-5). Greenspace quantity was measured by both remote sensing-based Normalized Difference Vegetation Index (NDVI) and Street View Greenness-quantity (SVG-quantity). Greenspace quality was measured by both Street View Greenness-quality (SVG-quality) and questionnaire-based self-reported greenspace quality. Structural equation models were used to assess mechanisms through which neighbourhood greenspace exposure has an influence on mental health. Stress, social cohesion, physical activity and life satisfaction were found to mediate both SVG-quality - WHO-5 scores and self-reported greenspace quality - WHO-5 scores associations. However, only NO₂ (nitrogen dioxide) mediated the association between NDVI and WHO-5 scores, while NO₂, perceived pollution and social cohesion mediated the association between SVG-quantity and WHO-5 scores. The mechanisms through which neighbourhood greenspace exposure influences mental health may vary across different exposure assessment strategies. Greenspace quantity influences mental health through reducing harm from pollution, while greenspace quality influences mental health through restoring and building capacities.

Continuous tightening emission standards (ESs) facilitate the reduction of organic gas emissions from gasoline vehicles. Correspondingly, it is essential to update the emissions and chemical speciation of total organic gases (TOGs), including volatile organic compounds (VOCs), intermediate volatility organic compounds (IVOCs), CH₄, and unidentified non-methane hydrocarbons (NMHCs) for assessing the formation of ozone and secondary organic aerosol (SOA). In this study, TOG and speciation emissions from 12 in-use light-duty gasoline vehicle (LDGV) exhausts, covering the ESs from China II to China V, were investigated on a chassis dynamometer under the Worldwide Harmonized Light-duty Test Cycle (WLTC) in China. The results showed that the most effectively controlled subgroup in TOG emissions from LDGVs was VOCs, followed by the unidentified NMHCs and IVOCs. The mass fraction of VOCs in TOGs also reduced from 61 ± 9% to 46 ± 18% while the IVOCs gently increased from 2 ± 0.4% to 8 ± 4% along with the more stringent ESs. For the VOC subsets, the removal efficiency of oxygenated VOCs (OVOCs) was lower than those of other VOC subsets in the ESs from China IV to V, suggesting the importance of OVOC emission controls for relatively new LDGVs. The IVOC emissions were mainly subject to the ESs, then driving cycles and fuel use. The formation potentials of ozone and SOA from LDGVs decreased separately 96% and 90% along with the restricted ESs from China II-III to China IV. The major contributor of SOA formation transformed from aromatics in the VOC subsets for China II-III vehicles to IVOCs for China IV/V vehicles, highlighting that IVOC emissions from LDGVs are also needed more attentions to control in future.

Benthic microbes play a crucial role in maintaining the biogeochemical balance of aquatic ecosystems especially the material cycling during plant decomposition. However, those systems in agricultural area are always threatened by agricultural run-off containing a mass of typical pathogenic invader- Escherichia coli. It is therefore vital to clarify the turnover, assembly, and geochemical functions of the E. coli invaded benthic prokaryotic microbial community during plant decomposition. During the decaying process, the key filtering factors of benthic community assembly were NH₄⁺-N (P < 0.001), NO₂⁻-N (P < 0.01), and Organic-N (P < 0.05). The E. coli colonized significantly in sediments (P < 0.001) and drove the turnover of the bacterial community (P = 0.001), which enhanced archaeal dominance in the benthic microbial network. E. coli also triggered niche structural variations. The biomass (%) of benthic nutrient cycling genera including Dechloromonas, Pseudomonas, Bacteroides, Candidatus_Methanofastidiosum, and Desulfomicrobium (P < 0.05) was altered by E. coli stress. The structural equation model illustrated that E. coli critically affected the benthic microbial geochemical functions in multiple pathways (P < 0.05). Our results provide new insights into benthic prokaryotic microbial community assembly and nutrient cycling and management under pollution stress.

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ₂₀₉PCBs in soils across China was in the range of 64.3–4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China.

This meta-analysis systematically evaluated the effects of water improvement and defluoridation on fluorosis-endemic areas in North and South China. The study used PubMed, Embase, China National Knowledge Infrastructure, and Wanfang to retrieve relevant research studies published between January 2000 and October 2019. The data included water fluoride levels, dental fluorosis prevalence in children 8–15 years of age, urinary fluoride levels in children and adults, and skeletal fluorosis prevalence in adults. Fixed-effects and random-effects models were used in the meta-analysis. A total of 17 research articles met the inclusion criteria and had an average water improvement period of 15.8 years. With water improvement, water fluoride levels decreased from 2.72 mg/L to 0.54 mg/L (95% confidence intervals: −2.75, −1.58), which was below the standard for drinking water (1.5 mg/L). Additionally, after water improvement, the prevalence of dental fluorosis decreased from 54.5% to 36.2% (95% confidence intervals: 0.12, 0.31) in children, and the prevalence of skeletal fluorosis decreased from 13.7% to 4.2% (95% confidence intervals: 0.16, 0.40) in adults. Urinary fluoride levels decreased from 3.06 mg/L to 1.70 mg/L (OR = −2.03, 95% confidence intervals: −2.77, −1.30) in children and from 2.29 mg/L to 1.72 mg/L (OR = −0.57, 95% confidence intervals: 0.65, −0.49) in adults. The results showed that the prevalence of dental fluorosis and skeletal fluorosis and urinary fluoride levels were significantly reduced by water improvement. This study findings revealed that the effects of water improvement and defluoridation were greater in South China than in North China, and it is obviously related to the time of water improvement and reducing fluoride.

Black carbon (BC) reacts with different substances to form secondary pollutants called aged black carbon, which causes inflammation and lung damage. BC and aged BC may enhance IL-33 in vivo, which may be derived from macrophages. The pro-inflammatory effect of IL-33 makes it essential to determine the source of IL-33, so it guides us to explore how to alleviate lung injury. In this study, a human bronchial epithelial cell line of 16HBE cells was selected, and aged BC (1,4-NQ coated BC and ozone oxidized BC) was used. We found that both BC and aged BC were able to up-regulate the mRNA expression of IL-1β, IL-6, and IL-8 except IL-33. However, the Mitogen-activated protein kinases (MAPKs) and Phosphatidylinositol 3-kinase (PI3K)/Protein kinase B (AKTs) pathways remained inactive. After pretreatment with Lipopolysaccharide (LPS), IL-33 mRNA expression was significantly increased in 16HBE cells and MAPKs and PI3K/AKT were activated. These results suggested that MAPKs and PI3K/AKT pathways were involved in the elevation of IL-33. Furthermore, epithelial cells are unlikely to be the source of lung inflammation caused by elevated IL-33 in BC and aged BC.