Association between fine particulate matter and oral cancer among Taiwanese men

Exposure to mixture particulate contaminants in the air and the risk of oral cancer: An updated systematic review and meta-analysis

The mixture of contaminants in the air (e.g., PM2.5, smoke) is a part of air pollutants that has become a hot environmental issue. Previous epidemiological studies have reported the relationship between wood smoke and PM2.5 exposure and oral cancer, but findings have been inconsistent. Therefore, this work designed to find out the relationship between mixture contaminants in air exposure and oral cancer. Fourteen studies were included through research in three databases before February 2024. Before analysis, the Newcastle-Ottawa Scale was applied to examine the quality of all selected studies. Then, the meta-analysis was carried out by meta-regression analysis, sensitivity analysis and subgroup analysis. The results showed that exposure to PM2.5 may have a positive association with oral cancer (pooled OR = 1.13, 95 % confidence interval: 1.06, 1.20). In contrast, no significant association was found between indoor air pollution and oral cancer. However, the result of the subgroup analysis indicated there is a significant association of indoor air pollution and oral cancer in developing countries (pooled OR = 2.5, 95 % confidence interval: 1.7, 3.6). In addition, the heterogeneity among studies of indoor air pollution exposure and oral cancer may caused by studies carried out in developed countries according to the subgroup and meta-regression analyses. In conclusion, the studies about indoor air pollution exposure and oral cancer are discrepant. The effects of mixed air contaminants for people's health are not simple and more studies are demanded to find out it in the future.

Integrated meta-analyses of genome-wide effects of PM2.5 in human cells identifies widespread dysregulation of genes and pathways associated with cancer progression and patient survival

Epidemiological studies have consistently shown a positive association between exposure to ambient PM2.5, a major component of air pollution, and various types of cancer. Previous biological research has primarily focused on the association between PM2.5 and lung cancer, with limited investigation into other cancer types. In this study, we conducted a meta-analysis on multiple PM2.5-treated normal human cell lines to identify potential molecular targets and pathways of PM2.5. Our analysis revealed 310 common differentially expressed genes (DEGs) that exhibited significant dysregulation upon exposure to PM2.5. These dysregulated genes covered a diverse range of functional categories, including oncogenes, tumor suppressor genes, and immune-related genes, which collectively contribute to PM2.5-induced carcinogenesis. Pathway enrichment analysis revealed the up-regulation of pathways associated with HIF-1, VEGF, and MAPK signalling, all of which have been implicated in various cancers. Induction in the levels of HIF pathway genes (HIF1⍺, HIF2⍺, VEGFA, BNIP3, EPO and PGK1) upon PM2.5 treatment was also confirmed by qRT-PCR. Furthermore, the construction of a protein-protein interaction (PPI) network unveiled hub genes, such as NQO1 and PDGFRB, that are known to be dysregulated and significantly correlated with overall survival in lung and breast cancer patients, suggesting their potential clinical significance. This study provides a deep insight into how PM2.5-mediated dysregulation of oncogenes or tumor suppressor genes across various human tissues may play an important role in PM2.5-induced carcinogenesis. Further exploration of these dysregulated molecular targets may enhance our understanding of the biological effects of PM2.5 and facilitate the development of preventive strategies and targeted therapies for PM2.5-associated cancers.

The Correlation between Oral Health and Air Pollution: A Systematic Review

This systematic review assessed to evaluate the potential correlation between oral health and air pollution. To the best of the authors' knowledge, this is the first systematic review endeavoring to compare air pollution and oral health. A systematic search was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement and employed the PICO(S) approach (Patient or Population, Intervention, Control or Comparison, Outcome, and Study types). The search was limited to English-language articles, and publications within a 15-year timeframe were included in the electronic search. A comprehensive search was conducted across PubMed, Scopus, Embase, and Web of Science databases, spanning the years 2008 to 2023, resulting in a total of 4983 scientific articles. A final selection of 11 scientific papers was made based on their study type and the specific air pollutants examined. The selected papers analyzed various air pollutants associated with health-related diseases, including Ozone, Nitrogen Dioxide, Nitrogen Monoxide, Carbon Monoxide, sulfur dioxide, and particulate matter. Three out of eleven of the reviewed studies assert a strong correlation between air pollutants and oral diseases, specifically periodontitis. However, the exact biological mechanisms underlying this correlation do not seem to be fully understood, indicating the need for further comprehensive investigation in this regard. Dentists can contribute to the collective effort by educating their patients about the oral health implications of air pollution, thereby supporting initiatives aimed at promoting environmental and health sustainability.

Outdoor air pollution exposure and uterine cancer incidence in the Sister Study

BACKGROUND

Outdoor air pollution is a ubiquitous exposure that includes endocrine-disrupting and carcinogenic compounds that may contribute to the risk of hormone-sensitive outcomes such as uterine cancer. However, there is limited evidence about the relationship between outdoor air pollution and uterine cancer incidence.

METHODS

We investigated the associations of residential exposure to particulate matter less than 2.5 µm in aerodynamic diameter (PM2.5) and nitrogen dioxide (NO2) with uterine cancer among 33 417 Sister Study participants with an intact uterus at baseline (2003-2009). Annual average air pollutant concentrations were estimated at participants' geocoded primary residential addresses using validated spatiotemporal models. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for the association between time-varying 12-month PM2.5 (µg/m3) and NO2 (parts per billion; ppb) averages and uterine cancer incidence.

RESULTS

Over a median follow-up period of 9.8 years, 319 incident uterine cancer cases were identified. A 5-ppb increase in NO2 was associated with a 23% higher incidence of uterine cancer (hazard ratio = 1.23, 95% confidence interval = 1.04 to 1.46), especially among participants living in urban areas (hazard ratio = 1.53, 95% confidence interval = 1.13 to 2.07), but  PM2.5 was not associated with increased uterine cancer incidence.

CONCLUSION

In this large US cohort, NO2, a marker of vehicular traffic exposure, was associated with a higher incidence of uterine cancer. These findings expand the scope of health effects associated with air pollution, supporting the need for policy and other interventions designed to reduce air pollutant exposure.

Association between ambient exposure to PM2.5 and upper aerodigestive tract cancer in Los Angeles

Fine particulate matter (PM2.5 ) contains carcinogens similar to those generated by tobacco smoking, which may increase the risks of developing smoking-related cancers, such as upper aerodigestive track (UADT) cancers, for both smokers and never-smokers. Therefore, it is imperative to understand the relation between ambient PM2.5 exposure and risk of UADT cancers. A population-based case-control study involving 565 incident UADT cancer cases and 983 controls was conducted in Los Angeles County from 1999 to 2004. The average residential PM2.5 concentration 1 year before the diagnosis date for cases and the reference date for controls was assessed using a chemical transport model. The association between ambient PM2.5 and the UADT cancers was estimated by unconditional logistic regression, adjusting for confounders at the individual and block-group level. Stratified analyses were conducted by sex, tobacco smoking status and UADT subsites. We also assessed the interaction between PM2.5 and tobacco smoking on UADT cancers. PM2.5 concentrations were associated with an elevated odds of UADT cancers (adjusted odds ratio = 1.21 per interquartile range [4.5 μg/m3 ] increase; 95% confidence interval: 1.02, 1.44). The association between PM2.5 and UADT cancers was similar across UADT subsites, sex and tobacco smoking status. The interaction between PM2.5 and tobacco smoking on UADT cancers was approximately additive on the odds scale. The effect estimate for PM2.5 and UADT cancers was similar among never smokers. Our findings support the hypothesis that exposure to PM2.5 increases the risk of UADT cancers. Improvements in air quality may reduce the risk of UADT cancers.

Glucocorticoids alleviate particulate matter-induced COX-2 expression and mitochondrial dysfunction through the Bcl-2/GR complex in A549 cells

Exposure to particulate matter (PM) causes mitochondrial dysfunction and lung inflammation. The cyclooxygenase-2 (COX-2) pathway is important for inflammation and mitochondrial function. However, the mechanisms by which glucocorticoid receptors (GRs) suppress COX-2 expression during PM exposure have not been elucidated yet. Hence, we examined the mechanisms underlying the dexamethasone-mediated suppression of the PM-induced COX-2/prostaglandin E2 (PGE2) pathway in A549 cells. The PM-induced increase in COX-2 protein, mRNA, and promoter activity was suppressed by glucocorticoids; this effect of glucocorticoids was antagonized by the GR antagonist RU486. COX-2 induction was correlated with the ability of PM to increase reactive oxygen species (ROS) levels. Consistent with this, antioxidant treatment significantly abolished COX-2 induction, suggesting that ROS is involved in PM-mediated COX-2 induction. We also observed a low mitochondrial membrane potential in PM-treated A549 cells, which was reversed by dexamethasone. Moreover, glucocorticoids significantly enhanced Bcl-2/GR complex formation in PM-treated A549 cells. Glucocorticoids regulate the PM-exposed induction of COX-2 expression and mitochondrial dysfunction and increase the interaction between GR and Bcl-2. These findings suggest that the COX-2/PGE2 pathway and the interaction between GR and Bcl-2 are potential key therapeutic targets for the suppression of inflammation under PM exposure.

Unlocking Modifiable Risk Factors for Alzheimer's Disease: Does the Oral Microbiome Hold Some of the Keys?

Advancing age is recognized as the primary risk factor for Alzheimer's disease (AD); however approximately one third of dementia cases are attributable to modifiable risk factors such as hypertension, diabetes, smoking, and obesity. Recent research also implicates oral health and the oral microbiome in AD risk and pathophysiology. The oral microbiome contributes to the cerebrovascular and neurodegenerative pathology of AD via the inflammatory, vascular, neurotoxic, and oxidative stress pathways of known modifiable risk factors. This review proposes a conceptual framework that integrates the emerging evidence regarding the oral microbiome with established modifiable risk factors. There are numerous mechanisms by which the oral microbiome may interact with AD pathophysiology. Microbiota have immunomodulatory functions, including the activation of systemic pro-inflammatory cytokines. This inflammation can affect the integrity of the blood-brain barrier, which in turn modulates translocation of bacteria and their metabolites to brain parenchyma. Amyloid-β is an antimicrobial peptide, a feature which may in part explain its accumulation. There are microbial interactions with cardiovascular health, glucose tolerance, physical activity, and sleep, suggesting that these modifiable lifestyle risk factors of dementia may have microbial contributors. There is mounting evidence to suggest the relevance of oral health practices and the microbiome to AD. The conceptual framework presented here additionally demonstrates the potential for the oral microbiome to comprise a mechanistic intermediary between some lifestyle risk factors and AD pathophysiology. Future clinical studies may identify specific oral microbial targets and the optimum oral health practices to reduce dementia risk.

Ambient Fine Particulate Matter and Cancer: Current Evidence and Future Perspectives

The high incidence of cancer has placed an enormous health and economic burden on countries around the world. In addition to evidence of epidemiological studies, conclusive evidence from animal experiments and mechanistic studies have also shown that morbidity and mortality of some cancers can be attributed to ambient fine particulate matter (PM_2.5) exposure, especially in lung cancer. However, the underlying carcinogenetic mechanisms of PM_2.5 remain unclear. Furthermore, in terms of risks of other types of cancer, both epidemiological and mechanistic evidence are more limited and scattered, and the results are also inconsistent. In order to sort out the carcinogenic effect of PM_2.5, this paper reviews the association of cancers with PM_2.5 based on epidemiological and biological evidence including genetic, epigenetic, and molecular mechanisms. The limitations of existing researches and the prospects for the future are also well clarified in this paper to provide insights for future studies.

Oral Cancer Incidence, Mortality, and Mortality-to-Incidence Ratio Are Associated with Human Development Index in China, 1990–2019

The burden of oral cancer (OC) is closely related to economic development. We aimed to evaluate the burden of OC at different stages of economic development in China in terms of incidence, mortality, and mortality-to-incidence ratio (MIR) from 1990 to 2019. Data on cancer in China from 1990 to 2019 were obtained from the Global Burden of Disease 2019. Based on human development index (HDI), Chinese economic development was divided into three stages: low, medium, and high HDI stages. Mann–Whitney U-test was used to evaluate the differences in age-standardised incidence rates (ASIR), age-standardised mortality rates (ASMR), and MIR at various stages of HDI. Correlation and regression tests were conducted to examine the association amongst ASIR, ASMR, MIR, and HDI in OC. The estimated annual percentage changes (EAPCs) were calculated to assess the trend of ASIR, ASMR, and MIR. Significant differences were observed in terms of ASIR, ASMR, and MIR between groups (P < 0.001). The values of both sexes in the low HDI stage were lower than those of the medium and high HDI stages, except for MIR, in which the low HDI stage was the highest (P < 0.05). ASIR and ASMR of OC in males at the medium HDI stage showed the fastest growth rate with EAPC values of 5.64 (95% confidence interval, 95% CI, 5.20 to 6.08) and 4.42 (95% CI, 4.01 to 4.82), respectively. A strong positive correlation exists between HDI and ASIR (r = 0.96) and ASMR (r = 0.91) in both sexes from 1990 to 2019. During the high HDI stage, the ASIR and ASMR of OC were at a high level, but the ASIR halted the uptrend trend and ASMR showed a decreasing trend. Therefore, the HDI index has been positively correlated with the ASIR and ASMR of OC in China in the past 30 years, but this relationship may not be sustained as the economy develops. The health department should continue to allocate additional resources for the prevention and treatment of OC.

Different Mortality Risks of Long-Term Exposure to Particulate Matter across Different Cancer Sites

Particulate matter (PM) air pollution has challenged the global community and the International Agency for Research on Cancer (IARC) classified airborne particulate matter as carcinogenic to humans. However, while most studies of cancer examined a single cancer type using different cohorts, few studies compared the associations of PM between different cancer types. We aimed to compare the association of long-term exposure to PM (PM₁₀ and PM_2.5) and cancer mortality across 17 different types of cancer using a population-based cohort in the Seoul Metropolitan Area (SMA), South Korea; Our study population includes 87,608 subjects (mean age: 46.58 years) residing in the SMA from the National Health Insurance Services-National Sample cohort (NHIS-NSC) and followed up for 2007-2015. We used the time-dependent Cox proportional hazards model to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) of each cancer mortality per 10 μg/m³ increase in PM concentrations, after adjusting for individual and areal characteristics. During eight years of follow-up, 1487 people died with any of 17 cancer types. Lung cancer death was the highest, followed by liver and stomach cancer. Although we did not find the association for all cancer types, possibly because of limited cancer cases, HRs of PM_2.5 were relatively high for lung, stomach, pancreas, non-Hodgkin's lymphoma, prostate, esophagus, oral and pharynx, and brain cancer mortality (HRs = 1.44-7.14). High HRs for pancreas, non-Hodgkin's lymphoma, esophagus, and oral and pharynx cancer were also seen for PM₁₀; our findings suggest PM air pollution as a potential risk factor of cancer mortality for upper digestive tracts, mouth, pancreas, and non-Hodgkin's lymphoma in a highly urbanized population with high exposure to PM for a long time.

Estimating LOCP cancer mortality rates in small domains in Spain using its relationship with lung cancer

The distribution of lip, oral cavity, and pharynx (LOCP) cancer mortality rates in small domains (defined as the combination of province, age group, and gender) remains unknown in Spain. As many of the LOCP risk factors are preventable, specific prevention programmes could be implemented but this requires a clear specification of the target population. This paper provides an in-depth description of LOCP mortality rates by province, age group and gender, giving a complete overview of the disease. This study also presents a methodological challenge. As the number of LOCP cancer cases in small domains (province, age groups and gender) is scarce, univariate spatial models do not provide reliable results or are even impossible to fit. In view of the close link between LOCP and lung cancer, we consider analyzing them jointly by using shared component models. These models allow information-borrowing among diseases, ultimately providing the analysis of cancer sites with few cases at a very disaggregated level. Results show that males have higher mortality rates than females and these rates increase with age. Regions located in the north of Spain show the highest LOCP cancer mortality rates.

Surfactin reduces particulate matter-induced VCAM-1-dependent monocyte adhesion in human gingival fibroblasts by increasing Nrf2-dependent HO-1 expression

BACKGROUND AND OBJECTIVES

The mechanisms of particulate matter (PM) toxicity involve the generation of ROS and upregulation of proinflammatory molecules. Nrf2 is a multifunctional cytoprotective transcription factor that regulates the expression of various antioxidant, anti-inflammatory, and detoxifying molecules, such as HO-1. As surfactin has potential to induce Nrf2 activation and HO-1 expression, this study aimed to investigate the anti-inflammatory effects of surfactin on PM-exposed human gingival fibroblasts (HGFs) and signaling pathways engaged by surfactin.

MATERIALS AND METHODS

Human gingival fibroblasts were challenged by PM with or without surfactin pretreatment. The expression of Nrf2, HO-1, VCAM-1, and other molecules was determined by western blot, real-time PCR, or ELISA. Human monocytic THP-1 cells labeled with fluorescent reagent were added to HGFs, and the cell adhesion was assessed. ROS generation and NADPH oxidase activity were also measured. The involvement of Nrf2/HO-1 and ROS signaling pathways was investigated by treating HGFs with specific pathway interventions, genetically or pharmacologically. One dose of surfactin was given to mice before PM treatment to explore its in vivo effect on VCAM-1 expression in gingival tissues.

RESULTS

Particulate matter led to VCAM-1-dependent monocyte adhesion in HGFs, which was regulated by PKCα/NADPH oxidase/ROS/STAT1/IL-6 pathway. Surfactin could attenuate monocyte adhesion by disrupting this VCAM-1-dependent pathway. Additionally, surfactin promoted Nrf2-dependent HO-1 expression in HGFs, mitigating VCAM-1 expression. PM-treated mice exhibited the lower expression of IL-6 and VCAM-1 in gingival tissues if they previously received surfactin.

CONCLUSION

Surfactin exerts anti-inflammatory effects against PM-induced inflammatory responses in HGFs by inhibiting VCAM-1-dependent pathway and inducing Nrf2/HO-1 axis.

Surfactin attenuates particulate matter-induced COX-2-dependent PGE2 production in human gingival fibroblasts by inhibiting TLR2 and TLR4/MyD88/NADPH oxidase/ROS/PI3K/Akt/NF-κB signaling pathway

OBJECTIVE

To evaluate the anti-inflammatory effects of surfactin and underlying mechanisms against particulate matter (PM)-induced inflammatory responses in human gingival fibroblasts (HGFs).

BACKGROUND

PM, a major air pollutant, may associate with certain oral diseases possibly by inducing inflammation and oxidative stress. Surfactin, a potent biosurfactant, possesses various biological properties including anti-inflammatory activity. However, the underlying mechanisms are unclear. Also, there is no study investigating the effects of surfactin on PM-induced oral inflammatory responses. As an essential constituent of human periodontal connective tissues which involves immune-inflammatory responses, HGFs serve as useful study models.

METHODS

HGFs were pretreated with surfactin prior to PM incubation. The PGE₂ production was determined by ELISA, while the protein expression and mRNA levels of COX-2 and upstream regulators were measured using Western blot and real-time PCR, respectively. The transcriptional activity of COX-2 and NF-κB were determined using promoter assay. ROS generation and NADPH oxidase activity were identified by specific assays. Co-immunoprecipitation assay, pharmacologic inhibitors, and siRNA transfection were applied to explore the interplay of molecules. Mice were given one dose of surfactin or different pharmacologic inhibitors, then PM was delivered into the gingiva for three consecutive days. Gingival tissues were obtained for analyzing COX-2 expression.

RESULTS

PM-treated HGFs released significantly higher COX-2-dependent PGE₂ , which were regulated by TLR2 and TLR4/MyD88/NADPH oxidase/ROS/PI3K/Akt/NF-κB pathway. PM-induced COX-2/PGE₂ increase was effectively reversed by surfactin through the disruption of regulatory pathway. Similar inhibitory effects of surfactin was observed in mice.

CONCLUSION

Surfactin may elicit anti-inflammatory effects against PM-induced oral inflammatory responses.

Associations of particulate matter with atopic dermatitis and chronic inflammatory skin diseases in South Korea

BACKGROUND

Particulate matter (PM) is a mixture of solid and liquid particles suspended in air, which originates from industrial plants or vehicle emissions. Although the skin is the primary body area of contact with air pollutants, the associations between PM and chronic inflammatory skin diseases has not been well established.

AIM

To investigate associations between PM and atopic dermatitis (AD) and between PM and other chronic inflammatory dermatoses, using data from the Korean Health Insurance Review and Assessment Service.

METHODS

Monthly disease statistics from the seven largest cities in South Korea (Seoul, Busan, Daegu, Incheon, Gwangju, Daejeon, Ulsan) and from Jeju Island (in total, a population of 23 288 000 for all eight areas) were included. Based on daily air pollution level and weather forecast from 2015 to 2019, multivariate negative binomial regression analysis was conducted to estimate monthly visits of AD with respect to outdoor air pollutants: coarse PM with a diameter of ≤ 10 μm (PM10) and fine PM with a diameter of ≤ 2.5 μm (PM2.5) ozone (O₃ ), nitrogen dioxide (NO₂ ), sulphur dioxide (SO₂ ) and carbon monoxide (CO).

RESULTS

Increases in the levels of PM2.5, PM10, SO₂ and CO were associated with significant increases in monthly patient visits for AD. Every 10 μg/m³ increase in PM2.5 and PM10 resulted in patient visit increases of 2.71% (95% CI 0.76-4.71; P < 0.01) and 2.01% (95% CI 0.92-3.11, P < 0.001), respectively, while every 1 part per billion (ppb) increase in SO₂ and every 100 ppb increase in CO resulted in visit increases of 2.26% (95% CI 1.35-3.17; P < 0.001) and 2.86% (95% CI 1.35-4.40; P < 0.001), respectively. O₃ and NO₂ were not associated with increased patient visits for AD. Increases in PM2.5 and PM10 concentrations were also significantly associated with increases in patient visits for psoriasis, seborrhoeic dermatitis and rosacea.

CONCLUSION

Our data suggest that PM is associated with AD and other chronic inflammatory skin diseases.

Ambient air pollution and ovarian cancer survival in California

OBJECTIVE

To examine whether exposure to ambient ozone, particulate matter with diameter less than 2.5 μm (PM_2.5), nitrogen dioxide (NO₂), and distance to major roadways (DTR) impact ovarian cancer-specific survival, while considering differences by stage, race/ethnicity, and socioeconomic status.

METHODS

Women diagnosed with epithelial ovarian cancer from 1996 to 2014 were identified through the California Cancer Registry and followed through 2016. Women's geocoded addresses were linked to pollutant exposure data and averaged over the follow-up period. Pollutants were considered independently and in multi-pollutant models. Cox proportional hazards models assessed hazards of disease-specific death due to environmental exposures, controlling for important covariates, with additional models stratified by stage at diagnosis, race/ethnicity and socioeconomic status.

RESULTS

PM_2.5 and NO₂, but not ozone or DTR, were significantly associated with survival in univariate models. In a multi-pollutant model for PM_2.5, ozone, and DTR, an interquartile range increase in PM_2.5 (Hazard Ratio [HR], 1.45; 95% Confidence Interval [CI], 1.41-1.49) was associated with worse prognosis. Similarly, in the multi-pollutant model with NO₂, ozone, and DTR, women with higher NO₂ exposures (HR for 20.0-30.0 ppb, 1.30; 95% CI, 1.25-1.36 and HR for >30.0 ppb, 2.48; 95% CI, 2.32-2.66) had greater mortality compared to the lowest exposed (<20.0 ppb). Stratified results show the effects of the pollutants differed by race/ethnicity and were magnified among women diagnosed in early stages.

CONCLUSIONS

Our analyses suggest that greater exposure to NO₂ and PM_2.5 may adversely impact ovarian cancer-specific survival, independent of sociodemographic and treatment factors. These findings warrant further study.

Fine Particulate Matter Air Pollution and Mortality Risk Among US Cancer Patients and Survivors

Background

Exposure to fine particulate matter (PM_2.5) air pollution has been linked to increased risk of mortality, especially cardiopulmonary and lung cancer mortality. It is unknown if cancer patients and survivors are especially vulnerable to PM_2.5 air pollution exposure. This study evaluates PM_2.5 exposure and risk for cancer and cardiopulmonary mortality in cohorts of US cancer patients and survivors.

Methods

A primary cohort of 5 591 168 of cancer patients and a 5-year survivor cohort of 2 318 068 was constructed using Surveillance, Epidemiology, and End Results Program data from 2000 to 2016, linked with county-level estimates of long-term average concentrations of PM_2.5. Cox proportional hazards models were used to estimate PM_2.5-mortality hazard ratios controlling for age-sex-race combinations and individual and county-level covariables.

Results

Of those who died, 26% died of noncancer causes, mostly from cardiopulmonary disease. Minimal PM_2.5-mortality associations were observed for all-cause mortality (hazard ratio [HR] = 1.01, 95% confidence interval [CI] = 1.00 to 1.03) per 10 µg/m³ increase in PM_2.5. Substantial adverse PM_2.5-mortality associations were observed for cardiovascular (HR = 1.32, 95% CI = 1.26 to 1.39), chronic obstructive pulmonary disease (HR = 1.10, 95% CI = 1.01 to 1.20), influenza and pneumonia (HR = 1.55, 95% CI = 1.33 to 1.80), and cardiopulmonary mortality combined (HR = 1.25, 95% CI = 1.21 to 1.30). PM_2.5-cardiopulmonary mortality hazard ratio was higher for cancer patients who received chemotherapy or radiation treatments.

Conclusions

Air pollution is adversely associated with cardiopulmonary mortality for cancer patients and survivors, especially those who received chemotherapy or radiation treatment. Given ubiquitous and involuntary air pollution exposures and large numbers of cancer patients and survivors, these results are of substantial clinical and public health importance.

Mechanistic Implications of Biomass-Derived Particulate Matter for Immunity and Immune Disorders

Particulate matter (PM) is a major and the most harmful component of urban air pollution, which may adversely affect human health. PM exposure has been associated with several human diseases, notably respiratory and cardiovascular diseases. In particular, recent evidence suggests that exposure to biomass-derived PM associates with airway inflammation and can aggravate asthma and other allergic diseases. Defective or excess responsiveness in the immune system regulates distinct pathologies, such as infections, hypersensitivity, and malignancies. Therefore, PM-induced modulation of the immune system is crucial for understanding how it causes these diseases and highlighting key molecular mechanisms that can mitigate the underlying pathologies. Emerging evidence has revealed that immune responses to biomass-derived PM exposure are closely associated with the risk of diverse hypersensitivity disorders, including asthma, allergic rhinitis, atopic dermatitis, and allergen sensitization. Moreover, immunological alteration by PM accounts for increased susceptibility to infectious diseases, such as tuberculosis and coronavirus disease-2019 (COVID-19). Evidence-based understanding of the immunological effects of PM and the molecular machinery would provide novel insights into clinical interventions or prevention against acute and chronic environmental disorders induced by biomass-derived PM.

Particulate matter (PM10) enhances RNA virus infection through modulation of innate immune responses

Sensing of pathogens by specialized receptors is the hallmark of the innate immunity. Innate immune response also mounts a defense response against various allergens and pollutants including particulate matter present in the atmosphere. Air pollution has been included as the top threat to global health declared by WHO which aims to cover more than three billion people against health emergencies from 2019 to 2023. Particulate matter (PM), one of the major components of air pollution, is a significant risk factor for many human diseases and its adverse effects include morbidity and premature deaths throughout the world. Several clinical and epidemiological studies have identified a key link between the PM existence and the prevalence of respiratory and inflammatory disorders. However, the underlying molecular mechanism is not well understood. Here, we investigated the influence of air pollutant, PM10 (particles with aerodynamic diameter less than 10 μm) during RNA virus infections using Highly Pathogenic Avian Influenza (HPAI) - H5N1 virus. We thus characterized the transcriptomic profile of lung epithelial cell line, A549 treated with PM10 prior to H5N1infection, which is known to cause severe lung damage and respiratory disease. We found that PM10 enhances vulnerability (by cellular damage) and regulates virus infectivity to enhance overall pathogenic burden in the lung cells. Additionally, the transcriptomic profile highlights the connection of host factors related to various metabolic pathways and immune responses which were dysregulated during virus infection. Collectively, our findings suggest a strong link between the prevalence of respiratory illness and its association with the air quality.

Surfactin from Bacillus subtilis induces apoptosis in human oral squamous cell carcinoma through ROS-regulated mitochondrial pathway

Recently, ambient air particulate matter (PM) has been shown to increase the risk of oral cancer. The most common malignant tumor in the oral cavity is oral squamous cell carcinoma (OSCC). Recent studies have revealed that surfactin, a cyclic lipopeptide generated by Bacillus subtilis, has anti-inflammatory and anti-cancer properties. However, the exact anti-cancer effects of surfactin on human OSCC and underlying molecular mechanisms remain largely unknown. In the present study, we found that treatment of SCC4 and SCC25 cells (human OSCC cell lines) with surfactin reduced the viability of SCC4 and SCC25 cells by induction of apoptosis. Surfactin-induced apoptosis was associated with caspase activation and poly(ADP-ribose) polymerase (PARP) cleavage and was regulated by the mitochondrial pathway, exemplified by mitochondrial depolarization, mitochondrial-derived reactive oxidative species (ROS) production, cytochrome c release, up-regulation of Bad and Bax, and down-regulation of Bcl-2. Surfactin induced NADPH oxidase-dependent ROS generation, which appeared essential for the activation of the mitochondrial pathway. Surfactin-induced mitochondrial-derived ROS generation was associated with JNK1/2 activation. After treatment with surfactin, ROS caused JNK1/2-dependent cell death of SCC4 and SCC25 cells. Taken together, our findings suggest that surfactin induces mitochondria associated apoptosis of human OSCC cell lines, and surfactin may be a potential chemotherapeutic agent for future OSCC treatment.

Potential effects of noxious chemical-containing fine particulate matter on oral health through reactive oxygen species-mediated oxidative stress: Promising clues

Nowadays, air pollution which is dominated by fine particulate matter with aerodynamic diameter less than or equal to 2.5 µm resulting from rapid industrialization and urbanization combined with population explosion has become more and more severe problem to mankind and the whole planet because of its diversity of deleterious effects. The latest data estimated that exposure to fine particulate matter, or PM2.5, contributes to approximately 4 million deaths worldwide due to cardiopulmonary conditions such as heart disease and stroke, respiratory infections, chronic lung disease and lung cancer. During recent years, there has been growing concern about the adverse effects of this global threat on oral health which is one of key components of general health and quality of life. Although a few studies have reported such possible association, the findings are still far from conclusion. Moreover, the underlying mechanisms remain unclear. To our knowledge, the analysis of literature regarding this scope has yet been published. Thus, current work systematically assesses existing evidences on the potential association between exposure to PM2.5 and the development of various oral diseases as well as figures out the plausible paradigm of PM2.5-induced damages in the oral cavity through its toxic chemical constituents along with its ability to induce oxidative stress via reactive oxygen species production. This might partially provide the clues for new research ideas and progression in the field of oral health.

Fine Particulate Matter Exposure and Cancer Incidence: Analysis of SEER Cancer Registry Data from 1992-2016

BACKGROUND

Previous research has identified an association between fine particulate matter (PM 2.5 ) air pollution and lung cancer. Most of the evidence for this association, however, is based on research using lung cancer mortality, not incidence. Research that examines potential associations between PM 2.5 and incidence of non-lung cancers is limited.

OBJECTIVES

The primary purpose of this study was to evaluate the association between the incidence of cancer and exposure to PM 2.5 using > 8.5  million cases of cancer incidences from U.S. registries. Secondary objectives include evaluating the sensitivity of the associations to model selection, spatial control, and latency period as well as estimating the exposure-response relationship for several cancer types.

METHODS

Surveillance, Epidemiology, and End Results (SEER) program data were used to calculate incidence rates for various cancer types in 607 U.S. counties. County-level PM 2.5 concentrations were estimated using integrated empirical geographic regression models. Flexible semi-nonparametric regression models were used to estimate associations between PM 2.5 and cancer incidence for selected cancers while controlling for important county-level covariates. Primary time-independent models using average incidence rates from 1992-2016 and average PM 2.5 from 1988-2015 were estimated. In addition, time-varying models using annual incidence rates from 2002-2011 and lagged moving averages of annual estimates for PM 2.5 were also estimated.

RESULTS

The incidences of all cancer and lung cancer were consistently associated with PM 2.5 . The incident rate ratios (IRRs), per 10 - μ g / m 3 increase in PM 2.5 , for all and lung cancer were 1.09 (95% CI: 1.03, 1.14) and 1.19 (95% CI: 1.09, 1.30), respectively. Less robust associations were observed with oral, rectal, liver, skin, breast, and kidney cancers.

DISCUSSION

Exposure to PM 2.5 air pollution contributes to lung cancer incidence and is potentially associated with non-lung cancer incidence. https://doi.org/10.1289/EHP7246.

The Inducible Role of Ambient Particulate Matter in Cancer Progression via Oxidative Stress-Mediated Reactive Oxygen Species Pathways: A Recent Perception

Simple Summary

Particulate matter, especially the fine fraction PM2.5, is officially stated as carcinogenic to human. There are compelling evidences on the association between PM2.5 exposure and lung cancer, and there are also some preliminary data reporting the significant links between this fraction with non-lung cancers. The underlying mechanisms remain unclear. Further studies related to such scope are highly required. The purpose of this work is to systemically analyze recent findings concerning the relationship between PM2.5 and cancer, and to thoroughly present the oxidative stress pathways mediated by reactive oxygen species as the key mechanism for carcinogenesis induced by PM2.5. This will provide a more comprehensive and updated knowledge regarding carcinogenic capacity of PM2.5 to both clinicians and public health workers, contributing to preventive and therapeutic strategies to fight against cancer in human.

Abstract

Cancer is one of the leading causes of premature death and overall death in the world. On the other hand, fine particulate matter, which is less than 2.5 microns in aerodynamic diameter, is a global health problem due to its small diameter but high toxicity. Accumulating evidence has demonstrated the positive associations between this pollutant with both lung and non-lung cancer processes. However, the underlying mechanisms are yet to be elucidated. The present review summarizes and analyzes the most recent findings on the relationship between fine particulate matter and various types of cancer along with the oxidative stress mechanisms as its possible carcinogenic mechanisms. Also, promising antioxidant therapies against cancer induced by this poison factor are discussed.

Surfactin from Bacillus subtilis attenuates ambient air particulate matter-promoted human oral cancer cells metastatic potential

Recently, many studies have indicated that ambient air particulate matter (PM) can increase the risk of oral cancer. The most common malignant tumor in the oral cavity is oral squamous cell carcinoma (OSCC). Usually, cancer cell migration/invasion is the most important cause of cancer mortality. Matrix metalloproteinase-2 (MMP-2) and MMP-9 have been shown to play important roles in regulating metastasis and the tumor microenvironment. Here, we studied the anti-cancer effects of surfactin, a cyclic lipopeptide generated by Bacillus subtilis, on cancer cell migration and invasion. Surfactin suppressed PM-promoted cell migration and invasion and colony formation of SCC4 and SCC25 human oral squamous cell carcinoma cell lines. We observed that PM induced MMP-2 and MMP-9 expression, which was inhibited by surfactin. Transfection with p65, p50, c-Jun, c-Fos, p85, p110, Akt, mammalian target of rapamycin (mTOR), or interleukin-6 (IL-6) siRNA markedly inhibited PM-induced MMP-2 and MMP-9 expression. Moreover, surfactin could reduce Akt, mTOR, p65, and c-Jun activation and IL-6 secretion induced by PM. Finally, we proved that transfection with Akt, p65, or c-Jun siRNA significantly inhibited PM-induced IL-6 release. Taken together, these results suggest that surfactin functions as a suppressor of PM-induced MMP2/9-dependent oral cancer cell migration and invasion by inhibiting the activation of phosphoinositide 3-kinase (PI3K)/Akt/mTOR and PI3K/Akt/nuclear factor-κB (NF-κB) and activator protein-1 (AP-1)/IL-6 signaling pathways.

Cancer mortality risk, fine particulate air pollution, and smoking in a large, representative cohort of US adults

PURPOSE

Air pollution and smoking are associated with various types of mortality, including cancer. The current study utilizes a publicly accessible, nationally representative cohort to explore relationships between fine particulate matter (PM2.5) exposure, smoking, and cancer mortality.

METHODS

National Health Interview Survey and mortality follow-up data were combined to create a study population of 635,539 individuals surveyed from 1987 to 2014. A sub-cohort of 341,665 never-smokers from the full cohort was also created. Individuals were assigned modeled PM2.5 exposure based on average exposure from 1999 to 2015 at residential census tract. Cox Proportional Hazard models were utilized to estimate hazard ratios for cancer-specific mortality controlling for age, sex, race, smoking status, body mass, income, education, marital status, rural versus urban, region, and survey year.

RESULTS

The risk of all cancer mortality was adversely associated with PM2.5 (per 10 µg/m3 increase) in the full cohort (hazard ratio [HR] 1.15, 95% confidence interval [CI] 1.08-1.22) and the never-smokers' cohort (HR 1.19, 95% CI 1.06-1.33). PM2.5-morality associations were observed specifically for lung, stomach, colorectal, liver, breast, cervix, and bladder, as well as Hodgkin lymphoma, non-Hodgkin lymphoma, and leukemia. The PM2.5-morality association with lung cancer in never-smokers was statistically significant adjusting for multiple comparisons. Cigarette smoking was statistically associated with mortality for many cancer types.

CONCLUSIONS

Exposure to PM2.5 air pollution contributes to lung cancer mortality and may be a risk factor for other cancer types. Cigarette smoking has a larger impact on cancer mortality than PM2.5 , but is associated with similar cancer types.

Nrf2/HO-1 partially regulates cytoprotective effects of carbon monoxide against urban particulate matter-induced inflammatory responses in oral keratinocytes

INTRODUCTION

Exposure to airborne particulate matter (PM) increases the proportion of oral inflammatory diseases. During the formation of inflammatory conditions, the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome activation plays an important regulator. Carbon monoxide (CO) arising from heme degradation, catalyzed particularly by heme oxygenase-1 (HO-1), has been shown to own cytoprotective effects including anti-inflammation and antioxidant. Here, we determined the novel mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on PM-induced inflammatory responses in human oral keratinocytes (HOKs).

METHODS

The effects of CORM-2 on the expression of various inflammatory proteins induced by PM were determined by Western blot, real-time PCR, promoter assay, and ELISA. The involvement of signaling molecules in these responses was studied by using the selective pharmacological inhibitors and siRNAs.

RESULTS

We proved that PM enhanced C-reactive protein (CRP) levels, NLRP3 inflammasome and caspase-1 activation, and IL-1β release, which were reduced by preincubation with CORM-2. Transfection with PKCα siRNA and preincubation with the ROS scavenger (N-acetyl-cysteine, NAC), an inhibitor of NADPH oxidase (diphenyleneiodonium, DPI), or the mitochondria-specific superoxide scavenger (MitoTEMPO) inhibited PM-mediated inflammatory responses. In addition, PM-regulated PKCα and NADPH oxidase activation as well as NADPH oxidase- and mitochondria-derived ROS generation were inhibited by CORM-2, but not inactivate CORM-2 (iCORM-2) pretreatment. At the end, we confirmed that CORM-2 improved PM-induced inflammatory responses via the induction of Nrf2 activation and HO-1 expression.

CONCLUSION

We suggest that CORM-2 inhibits PM-induced inflammatory responses in HOKs via the inhibition of PKCα/ROS/NLRP3 inflammasome activation combined with the induction of Nrf2/HO-1 expression.

Comparing the lung cancer burden of ambient particulate matter using scenarios of air quality standards versus acceptable risk levels

OBJECTIVES

Ambient particulate matter (PM) is regulated with science-based air quality standards, whereas carcinogens are regulated with a number of "acceptable" cases. Given that PM is also carcinogenic, we identify differences between approaches.

METHODS

We assessed the lung cancer deaths for Switzerland attributable to exposure to PM up to 10 µm (PM10) and to five particle-bound carcinogens. For PM10, we used an epidemiological approach based on relative risks with four exposure scenarios compared to two counterfactual concentrations. For carcinogens, we used a toxicological approach based on unit risks with four exposure scenarios.

RESULTS

The lung cancer burden using concentrations from 2010 was 10-14 times larger for PM10 than for the five carcinogens. However, the burden depends on the underlying exposure scenarios, counterfactual concentrations and number of carcinogens. All scenarios of the toxicological approach for five carcinogens result in a lower burden than the epidemiological approach for PM10.

CONCLUSIONS

Air quality standards-promoted so far by the WHO Air Quality Guidelines-provide a more appealing framework to guide health risk-oriented clean air policymaking than frameworks based on a number of "acceptable" cases.

Association between coarse particulate matter (PM10-2.5) and nasopharyngeal carcinoma among Taiwanese men

The nasopharyngeal tract traps mainly coarse particles in inhaled air. Soluble carcinogenic compounds, endotoxins, and trace metals contained in these particles are potential causes of inflammation and oxidative stress which could enhance carcinogenesis. The aim of this study was to determine the association between coarse particulate matter (PM10-2.5) and nasopharyngeal cancer (NPC). A total of 521,098 men (355 cases and 520,743 non-cases), aged ≥40 years were included in this study. Data were retrieved from the Taiwan Cancer Registry, the Adult Preventive Medical Services Database, and the Air Quality Monitoring Database. PM10-2.5 was significantly associated with a higher risk of NPC after adjusting for SO2, NOx, O3, age, body mass index, smoking, alcohol drinking, betel nut chewing, exercise, hypertension, diabetes, and hyperlipidemia. With PM10-2.5<20.44 μg/m3 as the reference, the ORs and 95% CIs were 1.47; 1.03-2.11, 1.34; 0.94-1.91, and 1.68; 1.16-2.44 for 20.44≤PM10-2.5<24.08, 24.08≤PM10-2.5<29.27, and PM10-2.5≥29.27 μg/m3, respectively. PM10-2.5 remained significantly associated with a higher risk of NPC after further adjustments were made for the aforementioned covariates and PM2.5 The ORs; 95% CIs were 1.42; 0.96 to 2.12, 1.41; 0.94 to 2.10, and 1.71; 1.10 to 2.66 for 20.44≤PM10-2.5<24.08, 24.08≤PM10-2.5<29.27, and PM10-2.5≥29.27 μg/m3, respectively. In conclusion, PM10-2.5 was significantly associated with a higher risk of NPC in Taiwanese men.

Measuring the administered dose of particles on the facial mucosa of a realistic human model

Exposure to particulate contaminants can cause serious adverse health effects. Deposition on the facial mucosa is an important path of exposure, but it is difficult to conduct direct dose measurement on real human subjects. In this study, we propose an in vitro method to assess the administered doses of micron-sized particles on the eyes and lips in which computed tomographic scanning and three-dimensional printing were used to create a model that includes a face, oropharynx, trachea, the first five generations of bronchi, and lung volume. This realistic model of a face and airway was exposed to monodispersed fluorescent particles released from an incoming jet. The administered dose of particles deposited upon the eyes and lips, as quantified by fluorescence intensity, was determined via a standard wiping protocol. The results show that, in this scenario, the administered doses normalized by source were 2.15%, 1.02%, 0.88%, 2.13%, and 1.55% for 0.6-, 1.0-, 2.0-, 3.0-, and 5.0-µm particles, respectively. The administered dose of large particles on the mucosa within a given exposure time has great significance. Moreover, the lips suffer a much greater risk of exposure than the eyes and account for more than 80% of total facial mucosa deposition. Our study provides a fast and economical method to assess the administered dose on the facial mucosa on an individual basis.

Associations between ambient air pollution and cancer incidence in Taiwan: an ecological study of geographical variations

BACKGROUND

Air pollution is a global public health concern. The World Health Organization has recently set up a goal of saving 7 million people globally by 2030 from air pollution related death. We conducted an ecological study of geographical variation to explore the association between air pollution (specifically, particulate matter <2.5 μm in aerodynamic diameter [PM2.5], particulate matter <10 μm in aerodynamic diameter, sulfur dioxide, nitrogen dioxide, nitric oxide, and ozone) and cancer incidence in Taiwan, from 2012 to 2016.

METHODS

In this study, the yearly average concentrations of each air pollutant at 75 air quality monitoring stations were calculated, and using the kriging method, the concentrations were extrapolated to each and every geographical central point of 349 local administrative areas of Taiwan. Spearman rank correlation coefficients between the age-adjusted cancer incidence rates and various air pollutants were calculated by stratifying genders and urbanization degrees of the local administrative areas. A total of 70 correlation coefficients were calculated.

RESULTS

In total, 17 correlation coefficients were significantly positive at an alpha level of 0.05. Among these, four correlation coefficients between the age-adjusted cancer incidence rates and PM2.5 levels remained significant after Bonferroni correction. For men in developing towns, general towns, and aged towns and for women in aged towns, the age-adjusted cancer incidence rates increased 13.1 (95% confidence interval [CI], 8.8-17.6), 11 (95% CI, 5.6-16.4), 16.7 (95% CI, 6.9-26.4), and 11.9 (95% CI, 5.6-18.2) per 100,000 populations, respectively, for every 1 μg/m3 increment in PM2.5 concentrations.

CONCLUSIONS

A significantly positive correlation was observed between the PM2.5 level and cancer incidence rate after multiple testing correction.