Personal exposure to PM2.5, genetic variants and DNA damage: a multi-center population-based study in Chinese

Environmental pollution and human fertility: investigating the relationship between PM2.5 exposure and assisted reproductive technology outcomes

OBJECTIVE

To investigate the impact of seasonal variations in particulate matter with an aerodynamic diameter of 2.5 µm or less (PM2.5) exposure on assisted reproductive technology (ART) outcomes.

METHODS

This retrospective study, conducted at the First People's Hospital of Shangqiu, analyzed data from 13,476 patients who underwent ART procedures between February 2018 and December 2022. Patients were categorized based on seasonal PM2.5 exposure levels. A generalized additive model (GAM), linear regression analysis, and multivariate logistic regression were used to assess the relationship between PM2.5 exposure and ART outcomes, including oocyte and embryo quality, pregnancy rates, live birth rates, and miscarriage rates.

RESULTS

Significant differences were observed in oocyte number, metaphase II (MII) oocyte number, transferable embryos, and good-quality embryos across seasonal PM2.5 exposure subgroups. Pregnancy rates and live birth rates also demonstrated statistically significant variations. Linear regression analysis revealed a consistent negative correlation between PM2.5 concentrations and key ART outcomes. Multivariate logistic regression analysis, adjusting for age and seasonal variations, confirmed a significant negative association between PM2.5 exposure and both pregnancy rates (OR = 0.995, 95% CI: 0.994-0.996, p < 0.001) and live birth rates (OR = 0.996, 95% CI: 0.995-0.997, p < 0.001). However, no significant relationship was found between PM2.5 exposure and miscarriage rates. GAM analysis further identified a nonlinear, threshold-like association between pregnancy outcomes and predictive factors, with significantly higher live birth rates observed in spring, summer, and autumn compared to winter.

CONCLUSIONS

The study complements existing evidence that exposure to PM2.5 can lead to decreased success rates of pregnancy and live births, as well as significantly impact the outcomes of ART. Future research should focus on developing strategies to mitigate the adverse effects of environmental pollution on ART success rates.

Effects of air pollution on the development and progression of digestive diseases: an umbrella review of systematic reviews and meta-analyses

Air pollution, especially particulate matter (PM), is one of the most common risk factors for global burden of disease. However, its effect on the risk of digestive diseases is unclear. Herein, we attempt to explore this issue by reviewing the existing evidence from published meta-analyses. We conducted a systematic literature search to identify all relevant meta-analyses regarding the association of air pollution with digestive diseases, and summarize their major findings. We assessed the methodological quality and evidence quality of the included meta-analyses using the AMSTAR-2 and GRADE tools, respectively, and the overlap of primary studies was assessed by the GROOVE tool. Nine meta-analyses were included in our analysis, containing 43 primary studies with high overlap. In the included meta-analyses, the methodological quality was from critically low to moderate, and the evidence quality was from very low to moderate. The exposure was primarily PM2.5. Seven, four, and one meta-analysis investigated the effect of air pollution on liver diseases, gastrointestinal diseases, and pancreatic diseases, respectively. PM2.5 exposure was significantly associated with liver dysfunction, chronic liver diseases, liver cancer, and colorectal cancer, but not oesophagus cancer, gastric cancer, or pancreatic cancer. Based on very low to moderate quality evidence from meta-analyses, PM2.5 exposure may contribute to the development of some digestive diseases, especially liver diseases.

The role of PM2.5 exposure in lung cancer: mechanisms, genetic factors, and clinical implications

Lung cancer is one of the most critical global health threats, as the second most common cancer and leading cause of cancer deaths globally. While smoking is the primary risk factor, an increasing number of cases occur in nonsmokers, with lung cancer in nonsmokers (LCNS) now recognized as the fifth leading cause of cancer mortality worldwide. Recent evidence identifies air pollution, particularly fine particulate matter (PM2.5), as a significant risk factor in LCNS. PM2.5 can increase oxidative stress and inflammation, induce genetic alterations and activation of oncogenes (including the epidermal growth factor receptor, EGFR), and contribute to lung cancer progression. This review summarizes the current understanding of how exposure to PM2.5 induces lung carcinogenesis and accelerates lung cancer development. It underscores the importance of prevention and early detection while calling for targeted therapies to combat the detrimental effects of air pollution. An integrated approach that combines research, public health policy, and clinical practice is essential to reduce the lung cancer burden and improve outcomes for those affected by PM2.5 exposurrre.

Could environmental exposure and climate change Be a key factor in the rising incidence of early onset colorectal cancer?

The emergence of early onset colorectal cancer (EOCRC) is believed to result from the complex interplay between external environmental factors and internal molecular processes. This review investigates the potential association between environmental exposure to chemicals and climate change and the increased incidence of EOCRC, focusing on their effects on gut microbiota (GM) dynamics. The manuscript explores the birth cohort effect, suggesting that individuals born after 1950 may be at higher risk of developing EOCRC due to cumulative environmental exposures. Furthermore, we also reviewed the impact of environmental pollution, including particulate matter and endocrine disrupting chemicals (EDCs), as well as global warming, on GM disturbance. Environmental exposures have the potential to disrupt GM composition and diversity, leading to dysbiosis, chronic inflammation, and oxidative stress, which are known risk factors associated with EOCRC. Particulate matter can enter the gastrointestinal tract, modifying GM composition and promoting the proliferation of pathogenic bacteria while diminishing beneficial bacteria. Similarly, EDCs, can induce GM alterations and inflammation, further increasing the risk of EOCRC. Additionally, global warming can influence GM through shifts in gut environmental conditions, affecting the host's immune response and potentially increasing EOCRC risk. To summarize, environmental exposure to chemicals and climate change since 1950 has been implicated as contributing factors to the rising incidence of EOCRC. Disruptions in gut microbiota homeostasis play a crucial role in mediating these associations. Consequently, there is a pressing need for enhanced environmental policies aimed at minimizing exposure to pollutants, safeguarding public health, and mitigating the burden of EOCRC.

The Comet Assay as a Tool in Human Biomonitoring Studies of Environmental and Occupational Exposure to Chemicals-A Systematic Scoping Review

Biomonitoring of human populations exposed to chemical substances that can act as potential mutagens or carcinogens, may enable the detection of damage and early disease prevention. In recent years, the comet assay has become an important tool for assessing DNA damage, both in environmental and occupational exposure contexts. To evidence the role of the comet assay in human biomonitoring, we have analysed original research studies of environmental or occupational exposure that used the comet assay in their assessments, following the PRISMA-ScR method (preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews). Groups of chemicals were designated according to a broad classification, and the results obtained from over 300 original studies (n = 123 on air pollutants, n = 14 on anaesthetics, n = 18 on antineoplastic drugs, n = 57 on heavy metals, n = 59 on pesticides, and n = 49 on solvents) showed overall higher values of DNA strand breaks in the exposed subjects in comparison with the unexposed. In summary, our systematic scoping review strengthens the relevance of the use of the comet assay in assessing DNA damage in human biomonitoring studies.

Exploring the adverse effect of fine particulate matter (PM2.5) on wildland firefighters' pulmonary function and DNA damage

Chiang Mai encounters severe pollution during the wildfire season. Wildland firefighters encounter various hazards while engaged in fire suppression operations, which encompass significant exposure to elevated concentrations of air pollutants resulting from combustion, especially particulate matter. The adverse effects of wildfire smoke on respiratory health are a significant concern. The objective of this study was to examine the potential adverse effects of PM2.5 exposure on the respiratory function and DNA damage of wildland firefighters. This prospective cohort study conducted in Chiang Mai from January to May 2022 planned to evaluate the health status of wildland firefighters during the pre-peak, peak, and post-peak ambient air pollution seasons. The measurement of PM2.5 was done at every forest fire station, as well as utilizing data from the Pollution Control Department. Participants received general health examinations, spirometry evaluations, and blood tests for DNA damage analysis. Pair t-tests and multiple regression models were used to examine the connection between pulmonary function parameters (FVC, FEV1) and PM2.5 concentration, with a significance level of P < 0.05. Thirty-three peak-season and twenty-one post-peak-season participants were enrolled. Four pre-peak-season wildland firefighters had FVC and FEV1 declines of > 15%. Multiple regression analysis showed a negative association between PM2.5 exposure and FVC% predicted (- 2.81%, 95% CI - 5.27 to - 0.34%, P = 0.027) and a marginally significant negative correlation with FVC (- 114.38 ml, 95% CI - 230.36 to 1.59 ml, P = 0.053). The remaining pulmonary measures showed a statistically insignificant decline. There were no significant changes in DNA damage detected. Wildland firefighters suffered a significant decline in pulmonary function associated with PM2.5 exposure. Spirometry is crucial for monitoring and promptly identifying respiratory issues that occur during wildfire seasons. Further research is recommended to explore DNA damage alterations and their potential association with PM2.5.

Genomic Characterization Revealed PM2.5-Associated Mutational Signatures in Lung Cancer Including Activation of APOBEC3B

Fine particulate matter (PM_2.5) exposure causes DNA mutations and abnormal gene expression leading to lung cancer, but the detailed mechanisms remain unknown. Here, analysis of genomic and transcriptomic changes upon a PM_2.5 exposure-induced human bronchial epithelial cell-based malignant transformed cell model in vitro showed that PM_2.5 exposure led to APOBEC mutational signatures and transcriptional activation of APOBEC3B along with other potential oncogenes. Moreover, by analyzing mutational profiles of 1117 non-small cell lung cancers (NSCLCs) from patients across four different geographic regions, we observed a significantly higher prevalence of APOBEC mutational signatures in non-smoking NSCLCs than smoking in the Chinese cohorts, but this difference was not observed in TCGA or Singapore cohorts. We further validated this association by showing that the PM_2.5 exposure-induced transcriptional pattern was significantly enriched in Chinese NSCLC patients compared with other geographic regions. Finally, our results showed that PM_2.5 exposure activated the DNA damage repair pathway. Overall, here we report a previously uncharacterized association between PM_2.5 and APOBEC activation, revealing a potential molecular mechanism of PM_2.5 exposure and lung cancer.

Auto repair workers exposed to PM2.5 particulate matter in Barranquilla, Colombia: telomere length and hematological parameters

Exposure to 2.5 µm particulate matter (PM_2.5) in automotive repair shops is associated with risks to health. We evaluated the effects of occupational exposure to PM_2.5 among auto repair-shop workers. Blood and urine samples were collected from 110 volunteers from Barranquilla, Colombia: 55 active workers and 55 controls. PM_2.5 concentrations were assessed at each of the sampling sites and chemical content was analyzed by SEM-EDS electron microscopy. The biological samples obtained were peripheral blood (hematological profiling, DNA extraction) and urine (malondialdehyde concentration). Telomere length was assessed by qPCR and polymorphisms in the glutathione transferase genes GSTT1 and GSTM1 by PCR-RFLP, with confirmation by allelic exclusion. White blood cell (WBC), lymphocyte (LYM%) and platelet (PLT) counts and the malondialdehyde concentration were higher (4.10 ± 0.93) in the exposed group compared to the control group (1.56 ± 0.96). TL was shorter (5071 ± 891) in the exposed individuals compared to the control group (6271 ± 805). White blood cell (WBC) and platelet counts were positively associated with exposure. Age and TBARS were correlated with TL in exposed individuals. The GSTT1 gene alleles were not in Hardy-Weinberg (H-W) equilibrium. The GSTM1 gene alleles were in H-W equilibrium and allelic exclusion analysis confirmed the presence of heterozygous GSTM1 genotypes. SEM-EDS analysis showed the presence of potentially toxic elements, including Mg, Al, Fe, Mn, Rh, Zn, and Cu. Auto repair shop workers showed effects that may be associated with exposure to mixtures of pollutants present in PM_2.5. The GSTM1 and GSTT1 genes had independent modulatory effects.

Efficacy of Low-Cost Sensor Networks at Detecting Fine-Scale Variations in Particulate Matter in Urban Environments

The negative health impacts of air pollution are well documented. Not as well-documented, however, is how particulate matter varies at the hyper-local scale, and the role that proximal sources play in influencing neighborhood-scale patterns. We examined PM2.5 variations in one airshed within Indianapolis (Indianapolis, IN, USA) by utilizing data from 25 active PurpleAir (PA) sensors involving citizen scientists who hosted all but one unit (the control), as well as one EPA monitor. PA sensors report live measurements of PM2.5 on a crowd sourced map. After calibrating the data utilizing relative humidity and testing it against a mobile air-quality unit and an EPA monitor, we analyzed PM2.5 with meteorological data, tree canopy coverage, land use, and various census variables. Greater proximal tree canopy coverage was related to lower PM2.5 concentrations, which translates to greater health benefits. A 1% increase in tree canopy at the census tract level, a boundary delineated by the US Census Bureau, results in a ~0.12 µg/m3 decrease in PM2.5, and a 1% increase in "heavy industry" results in a 0.07 µg/m3 increase in PM2.5 concentrations. Although the overall results from these 25 sites are within the annual ranges established by the EPA, they reveal substantial variations that reinforce the value of hyper-local sensing technologies as a powerful surveillance tool.

Dependence Analysis of PM2.5 Concentrations in 295 Chinese Cities in the Winter of 2019–2020

Considering the current severe atmospheric pollution problems in China, a comprehensive understanding of the distribution and spatial variability of PM2.5 is critically important for controlling pollution and improving the future atmospheric environment. This study first explored the distribution of PM2.5 concentrations in China, and then developed a methodology of “dependence analysis” to investigate the relationship of PM2.5 in different cities in China. The data of daily PM2.5 concentrations were collected from the environmental monitoring stations in 295 cities in China. This study also developed a set of procedures to evaluate the spatial dependence of PM2.5 among the 295 Chinese cities. The results showed that there was a total of 154 city pairs with dependence type “11”, under a significance level of 0.5%. Dependence type “11” mainly occurred between nearby cities, and the distance between 89.0% of the dependent city pairs was less than 200 km. Furthermore, the dependent pairs mainly clustered in the North China Plain, the Northeast Plain, the Middle and Lower Yangtze Plain and the Fen-Wei Plain. The geographic conditions of the Plain areas were more conducive to the spread of PM2.5 contaminants, while the mountain topography was unfavorable for the formation of PM2.5 dependencies. The dependent city couples with distances greater than 200 km were all located within the Plain areas. The high concentration of PM2.5 did not necessarily lead to PM2.5 dependences between city pairs. The methodology and models developed in this study will help explain the concentration distributions and spatial dependence of the main atmospheric pollutants in China, providing guidance for the prevention of large-scale air pollution, and the improvement of the future atmospheric environment.

Air pollution: A culprit of lung cancer

Air pollution is a global health problem, especially in the context of rapid economic development and the expansion of urbanization. Herein, we discuss the harmful effects of outdoor and indoor pollution on the lungs. Ambient particulate matters (PMs) from industrial and vehicle exhausts is associated with lung cancer. Workers exposed to asbestos, polycyclic aromatic hydrocarbons (PAHs), and toxic metals are also likely to develop lung cancer. Indoors, cooking fumes, second-hand smoke, and radioactive products from house decoration materials play roles in the development of lung cancer. Bacteria and viruses can also be detrimental to health and are important risk factors in lung inflammation and cancer. Specific effects of lung cancer caused by air pollution are discussed in detail, including inflammation, DNA damage, and epigenetic regulation. In addition, advanced materials for personal protection, as well as the current government policies to prevent air pollution, are summarized. This review provides a basis for future research on the relationship between lung cancer and air pollution.

Real-world PM2.5 exposure induces pathological injury and DNA damage associated with miRNAs and DNA methylation alteration in rat lungs

Fine particulate matter (PM_2.5) has been demonstrated to threaten public health and increase lung cancer risk. DNA damage is involved in the pathogenesis of lung cancer. However, the mechanisms of epigenetic modification of lung DNA damage are still unclear. This study developed a real-world air PM_2.5 inhalation system and exposed rats for 1 and 2 months, respectively, and investigated rat lungs pathological changes, inflammation, oxidative stress, and DNA damage effects. OGG1 and MTH1 expression was measured, along with their DNA methylation status and related miRNAs expression. The results showed that PM_2.5 exposure led to pathological injury, influenced levels of inflammatory cytokines and oxidative stress factors in rat lungs. Of note, 2-month PM_2.5 exposure aggravated pathological injury. Besides, PM_2.5 significantly elevated OGG1 expression and suppressed MTH1 expression, which was correlated to oxidative stress and partially mediated by reducing OGG1 DNA methylation status and increasing miRNAs expression related to MTH1 in DNA damage with increases of γ-H2AX, 8-OHdG and GADD153. PM_2.5 also activated c-fos and c-jun levels and inactivated PTEN levels in rat lungs. These suggested that epigenetic modification was probably a potential mechanism by which PM_2.5-induced genotoxicity in rat lungs.

Physicochemical and isotopic properties of ambient aerosols and precipitation particles during winter in Seoul, South Korea

The aim of this study was to characterize the physicochemical properties and microbial communities of particulate matter (PM) in Seoul, Korea. We collected long-term (2017-2019) precipitation samples and PM₁₀ and PM_2.5 monitoring data to determine the impact of soluble and insoluble chemical species on the soil surface. Ambient PM₁₀ concentrations were higher than PM_2.5 concentrations during the monitoring period, but both decreased during rainfall due to the washing effect of precipitation. PM_2.5 particles had a "fluffy" shape and contained sulfur (0.2%), but suspended particles (SPs) contained many carbon particles (approximately 60%). Spherical particles containing metal oxides, Fe and Al, might be originated from coal combustion, wild fires, and metal-refining processes under high-temperature conditions. Dissolved ions in precipitation included those eluted from salts and coal combustion based on the correlation coefficients of Na and Cl (R = 0.953) and F and NO₃ (R = 0.706). The δ¹⁵N-NO₃ and δ³⁴S-SO₄ of precipitation were enriched as the atmospheric temperature decreased from 9.8 to -1.6°C, implying the influence of domestic coal combustion. Backward trajectories showed that, in winter, air parcels passed through industrialized cities from China to South Korea. The microbial communities associated with PM were strongly influenced by atmospheric conditions. Proteobacteria (range from 4.6 to 76.7%) and Firmicutes (range from 6.0 to 91.4%) were the most dominant phyla and were significantly affected by changes in the PM_2.5 environment. The results indicate that the acidity of precipitation and the composition of aerosols were affected by fossil fuel combustion and mineral dust, and that atmospheric conditions may change as PM_2.5 concentrations increase.

The lag effect of exposure to PM2.5 on esophageal cancer in urban-rural areas across China

Exposure to PM2.5 pollution is a significant health concern and increases risks for cancers in China. However, the studies regarding the effect of PM2.5 and esophageal cancer incidence (ECI) among urban-rural areas are limited. In this study, we examined the sex- and area-specific association between exposure to PM2.5 and ECI, as well as explored the corresponding lag effects on ECI using a geographical weighted Poisson regression. We found significantly positive effect on ECI for males and females in different models, with the greatest increase of 1.44% (95% CI: 1.30%, 1.59%) and 2.42% (95% CI: 2.17%, 2.66%) in per 10 ug/m3 increase of PM2.5 for males and females at single year lag7 and lag4 after all covariates controlled, respectively. We also found that the long-term effect of PM2.5 on ECI was relatively stable at all moving average year lags. Moreover, rural areas had higher ECI risks for males (0.17%) and females (0.64%) with longer lag period than urban areas. In addition, higher risks for both sexes appeared in north, northwestern, and east China. The findings indicated that long-term exposure to PM2.5 was significantly associated with increased risks for ECI, which reinforce a comprehensive understanding for ECI related to PM2.5.

The effect of toxic components on metabolomic response of male SD rats exposed to fine particulate matter

PM_2.5 pollution was associated with numerous adverse health effects. However, PM_2.5 induced toxic effects and the relationships with toxic components remain largely unknown. To evaluate the metabolic toxicity of PM_2.5 at environmentally relevant doses, investigate the seasonal variation of PM_2.5 induced toxicity and the relationship with toxic components, a combination of general pathophysiological tests and metabolomics analysis was conducted in this study to explore the response of SD rats to PM_2.5 exposure. The result of general toxicology analysis revealed unconspicuous toxicity of PM_2.5 under environmental dose, but winter PM_2.5 at high dose caused severe histopathological damage to lung. Metabolomic analysis highlighted significant metabolic disorder induced by PM_2.5 even at environmentally relevant doses. Lipid metabolism and GSH metabolism were primarily influenced by PM_2.5 exposure due to the high levels of heavy metals. In addition, high levels of organic compounds such as PAHs, PCBs and PCDD/Fs in winter PM_2.5 bring multiple overlaps on the toxic pathways, resulting in larger pulmonary toxicity and metabolic toxicity in rats than summer.

A prospective study of the associations among fine particulate matter, genetic variants, and the risk of colorectal cancer

BACKGROUND

Fine particulate matter (PM_2.5) is suspected to increase the risk of colorectal cancer, but the mechanism remains unknown. We aimed to investigate the association between PM_2.5 exposure, genetic variants and colorectal cancer risk in the Prostate, Lung, Colon and Ovarian (PLCO) Cancer Screening trial.

METHODS

We included a prospective cohort of 139,534 cancer-free individuals from 10 United States research centers with over ten years of follow-up. We used a Cox regression model to assess the association between PM_2.5 exposure and colorectal cancer incidence by calculating the hazard ratio (HR) and 95% confidence interval (CI) with adjustment for potential confounders. The polygenic risk score (PRS) and genome-wide interaction analysis (GWIA) were used to evaluate the multiplicative interaction between PM_2.5 exposure and genetic variants in regard to colorectal cancer risk.

RESULTS

After a median of 10.43 years of follow-up, 1,666 participants had been diagnosed with colorectal cancer. PM_2.5 exposure was significantly associated with an increased risk of colorectal cancer (HR = 1.27; 95% CI = 1.17-1.37 per 5 μg/m³ increase). Five independent susceptibility loci reached statistical significance at P < 1.22 × 10^-8 in the interaction analysis. Furthermore, a joint interaction was observed between PM_2.5 exposure and the PRS based on these five loci with colorectal cancer risk (P = 3.11 × 10^-29). The Gene Ontology analysis showed that the vascular endothelial growth factor (VEGF) receptor signaling pathway was involved in the biological process of colorectal cancer.

CONCLUSIONS

Our large-scale analysis has shown for the first time that long-term PM_2.5 exposure potential increases colorectal cancer risk, which might be modified by genetic variants.

Impact of air pollution exposure during various periods of pregnancy on term birth weight: a large-sample, retrospective population-based cohort study

Previous studies have suggested that maternal exposure to air pollution might affect term birth weight. However, the conclusions are controversial. Birth data of all term newborns born in Xi'an city of Shaanxi, China, from 2015 to 2018 and whose mother lived in Xi'an during pregnancy were selected form the Birth Registry Database. And the daily air quality data of Xi'an city was collected from Chinese Air Quality Online Monitoring and Analysis Platform. Generalized additive models (GAM) and 2-level binary logistic regression models were used to estimate the effects of air pollution exposure on term birth weight, the risk term low birth weight (TLBW), and macrosomia. Finally, 321521 term newborns were selected, including 4369(1.36%) TLBW infants and 24,960 (7.76%) macrosomia. The average pollution levels of PM2.5, PM10, and NO2 in Xi'an city from 2015 to 2018 were higher than national limits. During the whole pregnancy, maternal exposure to PM2.5, PM10, SO2, and CO all significantly reduced the term birth weight and increased the risk of TLBW. However, NO2 and O3 exposure have significantly increased the term birth weight, and O3 even increased the risk of macrosomia significantly. Those effects were also observed in the first and second trimesters of pregnancy. But during the third trimester, high level of air quality index (AQI) and maternal exposure to PM2.5, PM10, SO2, NO2, and CO increased the term birth weight and the risk of macrosomia, while O3 exposure was contrary to this effect. The findings suggested that prenatal exposure to air pollution might cause adverse impacts on term birth weight, and the effects varied with trimesters and pollutants, which provides further pieces of evidence for the adverse effects of air pollution exposure in heavy polluted-area on term birth weight.

Long-term exposure to PM2.5 and Children's lung function: a dose-based association analysis

Background

The current literature is still not consist regarding the effect of long-term exposure to PM2.5 and children’s lung function, partly due to inadequate or inaccurate exposure assessment. In this study, we aim to investigate the associations between long-term exposure to PM2.5, estimated as average daily dose (ADD), and lung function in school-age children.

Methods

We recruited 684 participants of 7–12 years old from the city of Lanzhou located in northwestern China. Participants underwent spirometric tests for lung function and responded to a questionnaire survey. Detailed information about individual air exposure and personal information were collected, including length of school hours, home address, age, gender, etc. Combining the spatial distribution of PM2.5 concentrations in the past 5 years and individual time-activity data, we estimated annual ADD for 5 years preceding the lung function tests and 5-year average ADD, respectively. We used multiple linear regression models to examine the associations between ADD values and lung function, controlling for a range of individual-level covariates.

Results

The 5-year average ADD among all the participants was 50.5 µg/kg-d, with higher values estimated for children living in the urban area than the suburban area, for boys than girls, and for children whose parents received a lower education attainment. We found that a 1 μg/kg-d increment in ADD of PM2.5 was associated with a 10.49 mL (95% CI: −20.47, −0.50) decrease in forced vital capacity (FVC) and a 7.68 mL (95% CI: −15.80, −0.44) decrease in forced exploratory volume in 1 second (FEV₁). Among the annual ADDs estimated for the preceding 5 years, the immediate past year prior to lung function measurement had the greatest effect on lung function. The effect was greater in girls than in boys. We found no associations between annual exposure of PM2.5 (instead of ADD) and lung function when defined concentration was used as an exposure variable.

Conclusions

Long-term PM2.5 exposure, when estimated as exposure dose averaged over a year or longer, was associated with statistically significant reductions in FVC and FEV1 in children of elementary-school age. Future studies may consider the use of individual-level dose estimates (as opposed to exposure concentrations) to improve the dose-response assessment.

Identification of genetic features associated with fine particulate matter (PM2.5) modulated DNA damage using improved random forest analysis

Recent studies have found multiple single nucleotide variants (SNVs) associated with DNA damage. However, previous association analysis may ignore the potential interaction effects between SNVs. Therefore, we used an improved random forest (RF) analysis to identify the SNVs related to personal DNA damage in exon-focused genome-wide association study (GWAS). A total of 301 subjects from three independent centers (Zhuhai, Wuhan, and Tianjin) were retained for analysis. An improved RF procedure was used to systematically screen key SNVs associated with DNA damage. Furthermore, we used genetic risk score (GRS) and mediation analysis to investigate the integrative effect and potential mechanism of these genetic variants on DNA damage. Besides, gene set enrichment analysis was conducted to identify the pathways enriched by key SNVs using the Data-driven Expression Prioritized Integration for Complex Traits (DEPICT). Finally, a set of 24 SNVs with the lowest mean square errors (MSE) were identified by improved RF analysis. Both weighted and unweighted GRSs were associated with increased DNA damage levels (P_weight < 0.001 and P_unweight < 0.001). Gene set enrichment analysis indicated that these loci were significantly enriched in several biological features associated with DNA damage. These findings suggested the role of SNVs in modifying DNA damage levels. It may be convincing that this improved RF analysis can effectively identify SNVs associated with DNA damage levels.

PM2.5 induces apoptosis, oxidative stress injury and melanin metabolic disorder in human melanocytes

Recent growing evidence suggested that particulate matter 2.5 (PM2.5) has strong toxic effects on skin systems. However, the possible effects and the mechanisms of PM2.5 on vitiligo remain poorly understood. Therefore, the present study aimed to further investigate the effects and possible mechanisms of PM2.5 on vitiligo. Human keratinocytes (HaCaT cells) and human melanocytes (PIG1 cells and PIG3V cells) were exposed to PM2.5 (0-200 µg/ml) for 24 h. The cell viability of the three cell lines was measured by a Cell Counting Kit-8 assay. The secretions of stem cell factor (SCF) and basic fibroblast growth factor (bFGF) in HaCaT cells were evaluated by ELISA. The melanin contents, cellular tyrosinase activity, apoptosis, cell migration, malondialdehyde (MDA) contents, superoxide dismutase (SOD) levels, glutathione peroxidase (GSH-Px) levels and related protein expressions in PIG1 cells and PIG3V cells were evaluated by a NaOH assay, DOPA assay, Annexin V-FITC/Propidium Iodide staining, MDA assay, SOD assay, GSH-Px assay and western blotting, respectively. It was demonstrated that PM2.5 exposure inhibited cell viability of all three cell lines (HaCaT, PIG1 and PIG3V cells). PM2.5 exposure attenuated the secretions of SCF and bFGF in HaCaT cells. Moreover, PM2.5 exposure attenuated the activation of tyrosinase and melanogenesis, inhibited cell migration, and induced apoptosis and oxidative stress injury in PIG1 cells and PIG3V cells. In addition, PM2.5 exposure caused upregulated cytosolic cytochrome C and activated caspase-3 in PIG1 cells and PIG3V cells. Furthermore, PM2.5 exposure activated the nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 signaling pathway. The present results suggested that PM2.5 exposure could inhibit the secretions of SCF and bFGF in keratinocytes, and cause oxidative stress injury and melanin metabolic disorder in melanocytes. Therefore, PM2.5 could be a new risk factor for vitiligo.

Assessment of PM2.5 monitoring using MicroPEM: A validation study in a city with elevated PM2.5 levels

Portable monitors such as MicroPEM can accurately characterize personal exposure of pollutants, which is critical for linking exposure and health effects of air pollution. The RTI (RTI International, Research Triangle Park, NC, USA) MicroPEM V3.2A provides both real-time fine particulate matter (PM_2.5) concentrations and time-integrated PM samples collected onto Teflon filters that can be used to correct real-time data as well as allow further lab chemical analysis of species on filters (e.g., metal, black carbon). Due to the optical reflectivity of local PM sources can be very different from available standard reference particles used for calibration by RTI, there is a need for gravimetric correction and validation at each study location. However, assessments of MicroPEM have been limited in locations with severe air pollution, such as Beijing. We selected a variety of weather and air quality conditions, including both clear and hazy days in Beijing, to compare PM_2.5 data among MicroPEMs as well as between MicroPEM and other types of samplers. We also compared MicroPEM real-time PM_2.5 concentrations with data from nearby fixed-sites. The results show MicroPEM performed well across a wide range of PM_2.5 concentrations (6-461 μg/m³) and MicroPEM data, after gravimetric correction, were consistent with those from moderate-volume samplers. Good agreement was also found between real-time data from MicroPEM and fixed-site data. The present study covered a wide range of pollution levels in actual environments and validated the usage of MicroPEM as a PM_2.5 monitor in locations with elevated PM_2.5 levels.

Association between single nucleotide polymorphism (rs4252424) in TRPV5 calcium channel gene and lead poisoning in Chinese workers

Background

Lead (Pb) is broadly used in various industries and causes irreversible damage to human tissues, organs, and systems. Studies have revealed that lead exerts toxic effects via interfering with calcium channel.

Methods

In the present study, we investigated whether single nucleotide polymorphisms (SNPs) in TRPV5, a calcium channel‐related gene, were associated with lead exposure susceptibility. By using TaqMan SNP genotyping, we performed genotyping of eight TRPV5 tag‐SNPs in 1,130 lead‐exposed Chinese workers with similar lead exposure level.

Results

Single nucleotide polymorphism rs4252424 was significantly associated with lead susceptibility, measured by blood lead level (BLL) (β = −0.069, p_linear = 0.029). However, there was no significant association between any other seven SNPs and BLL. The further expression Quantitative Trait Loci displayed that CC genotype of rs4252424 is significant associated with higher BLL than CT (p < 0.0001).

Conclusion

We conclude that SNP rs4252424 has the potential to evaluate lead susceptibility in the Chinese occupational population, and further enhance lead exposure prevention and intervention.

Genetic variants in nuclear DNA along with environmental factors modify mitochondrial DNA copy number: a population-based exome-wide association study

Background

Mitochondrial DNA (mtDNA) copy number has been found associated with multiple diseases, including cancers, diabetes and so on. Both environmental and genetic factors could affect the copy number of mtDNA. However, limited study was available about the relationship between genetic variants and mtDNA copy number. What’s more, most of previous studies considered only environmental or genetic factors. Therefore, it’s necessary to explore the genetic effects on mtDNA copy number with the consideration of PM_2.5 exposure and smoking.

Results

A multi-center population-based study was performed with 301 subjects from Zhuhai, Wuhan and Tianjin. Personal 24-h PM_2.5 exposure levels, smoking and mtDNA copy number were evaluated. The Illumina Human Exome BeadChip, which contained 241,305 single nucleotide variants, was used for genotyping. The association analysis was conducted in each city and meta-analysis was adopted to combine the overall effect among three cities. Seven SNPs showed significant association with mtDNA copy number with P value less than 1.00E-04 after meta-analysis. The following joint analysis of our identified SNPs showed a significant allele-dosage association between the number of variants and mtDNA copy number (P = 5.02 × 10^− 17). Further, 11 genes were identified associated with mtDNA copy number using gene-based analysis with a P value less than 0.01.

Conclusion

This study was the first attempt to evaluate the genetic effects on mtDNA copy number with the consideration of personal PM_2.5 exposure level. Our findings could provide more evidences that genetic variants played important roles in modulating the copy number of mtDNA.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5142-7) contains supplementary material, which is available to authorized users.

A proposed methodology for impact assessment of air quality traffic-related measures: The case of PM2.5 in Beijing

Air quality traffic-related measures have been implemented worldwide to control the pollution levels of urban areas. Although some of those measures are claiming environmental improvements, few studies have checked their real impact. In fact, quantitative estimates are often focused on reducing emissions, rather than on evaluating the actual measures' effect on air quality. Even when air quality studies are conducted, results are frequently unclear. In order to properly assess the real impact on air quality of traffic-related measures, a statistical method is proposed. The method compares the pollutant concentration levels observed after the implementation of a measure with the concentration values of the previous year. Short- and long-term impact is assessed considering not only their influence on the average pollutant concentration, but also on its maximum level. To control the effect of the main confounding factors, only the days with similar environmental conditions are analysed. The changeability of the key meteorological variables that affect the transport and dispersion of the pollutant studied are used to identify and group the days categorized as similar. Resemblance of the pollutants' concentration of the previous day is also taken into account. The impact of the road traffic measures on the air pollutants' concentration is then checked for those similar days using specific statistical functions. To evaluate the proposed method, the impact on PM_2.5 concentrations of two air quality traffic-related measures (M1 and M2) implemented in the city of Beijing are taken into consideration: M1 was implemented in 2009, restricting the circulation of yellow-labelled vehicles, while M2 was implemented in 2014, restricting the circulation of heavy-duty vehicles. To compare the results of each measure, a time-period when these measures were not applied is used as case-control.

Ambient Air Pollution and Biomarkers of Health Effect

Recently, the air pollution situation of our country is very serious along with the development of urbanization and industrialization. Studies indicate that the exposure of air pollution can cause a rise of incidence and mortality of many diseases, such as chronic obstructive pulmonary disease (COPD), asthma, myocardial infarction, and so on. However, there is now growing evidence showing that significant air pollution exposures are associated with early biomarkers in various systems of the body. In order to better prevent and control the damage effect of air pollution, this article summarizes comprehensively epidemiological studies about the bad effects on the biomarkers of respiratory system, cardiovascular system, and genetic and epigenetic system exposure to ambient air pollution.

Flavone protects HBE cells from DNA double-strand breaks caused by PM2.5

Ambient air particulate matter 2.5 (PM2.5) contains many harmful components that can enter the circulatory system and produce reactive oxygen species (ROS) in body. Oxidative stress and DNA damage induced by ROS may affect any cellular macromolecule and lead to DNA double-strand breaks (DSBs). Flavonoids, widely distributed in some herbs and berries, have been proved having anti-oxidative or anti-cancer efficacy. In this study, we investigated whether Flavone, a kind of flavonoids, can protect human bronchial epithelial cells (HBE) from DSBs caused by PM2.5 and how this function is probably implemented. We found that cells exposed to PM2.5 obviously induced viability inhibition, DNA damage and part of apoptosis. However, Flavone treatment prior to PM2.5 apparently improved cell viability, and mitigated the formation of 8-hydroxy-2-deoxyguanosine, the expression of DNA damage-relative protein and cell apoptosis. Our studies demonstrated that PM2.5 induced oxidative DSBs while Flavone ameliorated the DNA damage and increased cell viability probably through influencing DNA repair mechanism of cells.

Effects of ambient PM2.5 and 9-nitroanthracene on DNA damage and repair, oxidative stress and metabolic enzymes in the lungs of rats

Ambient fine particulate matter (PM2.5) is a complex mixture associated with lung cancer risk. PM2.5-bound nitro-polycyclic aromatic hydrocarbons (NPAHs) have been demonstrated to possess mutagenicity and carcinogenicity. Previous studies showed that PM2.5 induced DNA damage, whereas there is little knowledge of whether 9-nitroanthracene (9-NA), a typical compound of NPAHs in PM2.5, causes DNA damage. Also, the regulating mechanisms of PM2.5 and 9-NA in DNA damage and repair are not yet fully established. Here we sought to investigate the molecular mechanisms of DNA damage and repair in the lungs of male Wistar rats exposed to PM2.5 (1.5 mg per kg body weight) or three different dosages of 9-NA. And then DNA strand breaks, 8-OH-dG formation, DNA-protein crosslink and DNA repair gene expressions in rat lungs were analyzed. In addition, alteration in oxidative stress factors and metabolic enzymes were detected. The results showed that (1) PM2.5 and higher dosage 9-NA (4.0 × 10-5 and 1.2 × 10-4 mg per kg body weight) significantly caused lung DNA damage, accompanied by increasing OGG1 expression while inhibiting MTH1 and XRCC1 expression, elevating the levels of GADD153, hemeoxygenase-1 and malondialdehyde, and promoting the activities of CYP450 isozymes and glutathione S-transferase. (2) 1.3 × 10-5 mg kg-1 9-NA exposure couldn't cause DNA damage and oxidative stress. (3) At the approximately equivalent dose level, PM2.5-induced DNA damage effects were more obvious than 9-NA with positive correlation. It suggests that DNA damage caused by PM2.5 and 9-NA may be mediated partially through influencing the DNA repair capacity and enhancing oxidative stress and biotransformation, and this negative effect of 9-NA might be related to the PM2.5-induced lung genotoxicity.

Genetic variants in autophagy associated genes are associated with DNA damage levels in Chinese population

Autophagy associated genes (ATGs) played an important role in the repair process of DNA damage and decreased autophagy may weaken the repair process and aggravate DNA damage. Based on this, we hypothesized that DNA damage levels might be modified by genetic variants in autophagy associated genes. In order to validate our hypothesis, 307 subjects were recruited from three different cities (Zhuhai, Wuhan and Tianjin) in China. Demographic data, individual 24-h PM_2.5 exposure and peripheral blood DNA damage levels were also detected. Seven potentially functional polymorphisms in four essential autophagy associated genes (ATG5, ATG7, ATG8 and ATG13) were screened to evaluate the relationship between the polymorphisms of autophagy associated genes and DNA damage levels. This association was assessed by using multivariable linear regression model, age, sex, smoke and PM_2.5 exposure levels were adjusted in each city. We found that rs12599322 in ATG8 (A>G, β=0.263, 95% CI: 0.108-0.419, P=8.98×10^-4) and rs7484002 in ATG13 (A>G, β=0.396, 95% CI: 0.085-0.708, P=0.013) were significantly associated with higher DNA damage levels. Furthermore, functional annotations showed that both rs12599322 and rs7484002 located at transcription factor binding sites (TFBS), indicating that they could regulate the expression of related genes through TF regulation. Following allelic trend analysis revealed that the DNA damage levels were significantly aggravated with the increasing number of risk variants in autophagy associated genes (P for trend: 8.09×10^-5). Our findings suggested that the polymorphisms in ATGs may influence DNA damage levels in one of the Chinese population.

Trends of PM2.5 concentrations in China: A long term approach

The fast economic growth of China along the last two decades has created a strong impact on the environment. The occurrence of heavy haze pollution days is the most visible effect. Although many researchers have studied such problem, a high number of spatio-temporal limitations in the recent studies were identified. From our best knowledge the long trends of PM_2.5 concentrations were not fully investigated in China, in particular the year-to-year trends and the seasonal and daily cycles. Therefore, in this work the PM_2.5 concentrations collected from automatic monitors from five urban sites located in megacities with different climatic zones in China were analysed: Beijing (40°N), Chengdu (31°N), Guangzhou (23°N), Shanghai (31°N) and Shenyang (43°N). For an inter-comparison a meta-analysis was carried out. An evaluation conducted since 1999 demonstrates that PM_2.5 concentrations have been reduced until 2008, period which match with the occurrence of the Olympic Games. However, a seasonal analysis highlight that such decrease occurs mostly during warmer seasons than cold seasons. During winter PM_2.5 concentrations are typically 1.3 to 2.7 higher than in summer. The average daily cycle shows that the lowest and highest PM_2.5 concentrations often occurs in the afternoon and evening hours respectively. Such daily variations are mostly driven by the daily variation of the boundary layer depth and emissions. Although the PM_2.5 levels have showing signs of improvement, even during the warming season the values are still too high in comparison with the annual environmental standards of China (35 μg m^-3). Moreover, during cold seasons the north regions have values twice higher than this limit. Thus, to fulfil these standards the governmental mitigation measures need to be strongly reinforced in order to optimize the daily living energy consumption, primarily in the north regions of China and during the winter periods.

Transcriptomic analyses of human bronchial epithelial cells BEAS-2B exposed to atmospheric fine particulate matter PM2.5

Respiratory exposure is the major route of atmospheric PM_2.5 entering the human body. Epidemiological studies have indicated that exposure to PM_2.5 is associated with increased risk of pulmonary diseases, but the underlying mechanisms remain less clear. In this study, human bronchial epithelial cells (BEAS-2B) were used to investigate the toxic effect and gene expression changes induced by PM_2.5 collected from Beijing, China, based on microarray and following bioinformatic analyses. Gene ontology (GO) analysis indicated that PM_2.5 caused significant changes in gene expression patterns related to a series of important functions, covering gene transcription, signal transduction, cell proliferation, cellular metabolic processes, immune response, etc. Additionally, pathway analysis and signal-net analysis showed that PI3K/Akt, MAPK, and TNF signaling pathways were the most prominently significant pathways affected by PM_2.5, which play key roles in regulating cell proliferation, cell differentiation, cytoskeleton regulation, and inflammatory response. Finally, for the purpose of verifing the accuracy of microarray analysis, qRT-PCR was used to detect the expression of part key genes in the above signaling pathways, which were selected from the signal-net. Our study provided a large amount of information on the molecular mechanism that underling PM_2.5 caused pulmonary diseases, and follow-up researches are still needed for further exploration.

Genetic variants in multisynthetase complex genes are associated with DNA damage levels in Chinese populations

Aminoacyl-tRNA synthetases (ARSs) and ARS-interacting multi-functional proteins (AIMPs) form a multisynthetase complex (MSC) and play an important role in the process of DNA damage repair. We hypothesized that genetic variants in key ARSs and AIMPs might regulate the DNA damage response. Therefore, we systematically screened 23 potentially functional polymorphisms in MSC genes and evaluated the association between the genetic variants and DNA damage levels in 307 subjects from three cities in southern, central and northern China (Zhuhai, Wuhan and Tianjin, respectively). We examined personal 24-h PM2.5 exposure levels and DNA damage levels in peripheral blood lymphocytes for each subject. We found that the variant allele of rs12199241 in AIMP3 was significantly associated with DNA damage levels (β=0.343, 95%CI: 0.133-0.554, P=0.001). Meanwhile, the results of rs5030754 in EPRS and rs3784929 in KARS indicated their suggestive roles in DNA damage processes (β=0.331, 95%CI: 0.062-0.599, P=0.016 for rs5030754; β=0.192, 95%CI: 0.016-0.368, P=0.033 for rs3784929, respectively). After multiple testing, rs12199241 was still significantly associated with DNA damage levels. Combined analysis of these three polymorphisms showed a significant allele-dosage association between the number of risk alleles and higher DNA damage levels (Ptrend<0.001). These findings indicate that genetic variants in MSC genes may account for PM2.5-modulated DNA damage levels in Chinese populations.