A curated review of recent literature of biomarkers used for assessing air pollution exposures and effects in humans

Neuroendocrine contribution to sex-related variations in adverse air pollution health effects

Air pollution exposure is ranked as a leading environmental risk factor for not only cardiopulmonary diseases but also for systemic health ailments including diabetes, reproductive abnormalities, and neuropsychiatric disorders, likely mediated by central neural stress mechanisms. Current experimental evidence links many air pollution health outcomes with activation of neuroendocrine sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal (HPA) stress axes associated with resultant increases in adrenal-derived hormone levels acting as circulating mediators of multi-organ stress reactions. Epidemiological and experimental investigations also demonstrated sex-specific responses to air pollutant inhalation, which may be attributed to hormonal interactions within the stress and reproductive axes. Sex hormones (androgens and estrogens) interact with neuroendocrine functions to influence hypothalamic responses, subsequently augmenting stress-mediated metabolic and immune changes. These neurohormonal interactions may contribute to innate sex-specific responses to inhaled irritants, inducing differing individual susceptibility. The aim of this review was to: (1) examine neuroendocrine co-regulation of the HPA axis by gonadal hormones, (2) provide experimental evidence demonstrating sex-specific respiratory and systemic effects attributed to air pollutant inhalation exposure, and (3) postulate proposed mechanisms of stress and sex hormone interactions during air pollution-related stress.

Multiple Chemical Sensitivity: It's time to catch up to the science

Multiple chemical sensitivity (MCS) is a complex medical condition associated with low dose chemical exposures. MCS is characterized by diverse features and common comorbidities, including fibromyalgia, cough hypersensitivity, asthma, and migraine, and stress/anxiety, with which the syndrome shares numerous neurobiological processes and altered functioning within diverse brain regions. Predictive factors linked to MCS comprise genetic influences, gene-environment interactions, oxidative stress, systemic inflammation, cell dysfunction, and psychosocial influences. The development of MCS may be attributed to the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1. Capsaicin inhalation challenge studies demonstrated that TRPV1 sensitization is manifested in MCS, and functional brain imaging studies revealed that TRPV1 and TRPA1 agonists promote brain-region specific neuronal variations. Unfortunately, MCS has often been inappropriately viewed as stemming exclusively from psychological disturbances, which has fostered patients being stigmatized and ostracized, and often being denied accommodation for their disability. Evidence-based education is essential to provide appropriate support and advocacy. Greater recognition of receptor-mediated biological mechanisms should be incorporated in laws, and regulation of environmental exposures.

A comprehensive overview of genotoxicity and mutagenicity associated with outdoor air pollution exposure in Brazil

This review examined the mutagenicity and genotoxicity associated with exposure to outdoor air pollutants in Brazil. A search was performed on the Web of Science database using a combination of keywords that resulted in 134 articles. After applying exclusion criteria, a total of 75 articles were obtained. The articles were classified into three categories: (1) studies with plants and animals, (2) in vitro studies, and (3) human biomonitoring. The investigations were conducted in 11 of 27 Brazilian states with the highest prevalence in the southeast and south regions. Only 5 investigations focused on the effects of burning biomass on the quality of outdoor air. Plants, especially Tradescantia pallida, were the main air pollution biomonitoring tool. When available, a significant association between levels of air pollutants and genetic damage was described. Among the in vitro studies, Salmonella/microsome is the most used test to evaluate mutagenesis of outdoor air in Brazil (n = 26). Human biomonitoring studies were the least frequent category (n = 18). Most of the investigations utilized micronucleus bioassay, in oral mucosa cells (n = 15) and lymphocytes (n = 5), and the comet assay (n = 6). The analysis in this study points to the existence of gaps in genotoxicity studies and our findings indicate that future studies need to address the variety of potential sources of pollution existing in Brazil. In addition to extent of the impacts, consideration should be given to the enormous Brazilian biodiversity, as well as the determination of the role of socioeconomic inequality of the population in the observed outcomes.

Metal contents in house geckos (Squamata: Gekkonidae) from industrial and urban areas of southern Tamaulipas, Mexico and western Andalucía, Spain, may reflect airborne metal pollution

House geckos share living quarters with humans in the tropical and subtropical regions inhabited by these reptiles. Gecko behavior, biological traits, continuous exposure to suspended particulate matter 0 µm in diameter (PM₁₀) and dust, as well as status as exotic species, motivated the choice of these species to examine environmental exposure to ambient air pollutants, in particular metals, and subsequent accumulation in these organisms. One part of the study was conducted in Tamaulipas (Mexico) where Hemydactylus frenatus is abundant in urban and industrial environments, the other part was conducted in Andalucia (Spain) where Tarentola mauritanica is found in similar environments. Adult geckos were collected on buildings in locations affected by various air pollution sources. For both species, higher metal contents were observed in whole-body (including digestive tracts) analysis and were markedly different between collection sites. Contents in tails, digestive tracts, and carcasses without digestive tracts were not correlated. Based on contamination factor values, bioaccumulation in H. frenatus tissues occurred for 12 of the 15 metals analyzed. Data suggest that H. frenatus might serve as a biomonitor for Cu, Ni, Pb, Cr, Li, and V, whereas T. mauritanica might be a biomonitor for Cu, Ni, Pb, and Cr. To our knowledge, metal contents for H. frenatus are reported here for the first time. House gecko data could be integrated into a highly representative monitoring system and health risk assessments related to air quality in residential areas.

Time trend of exposure to secondhand tobacco smoke and polycyclic aromatic hydrocarbons between 1995 and 2019 in Germany - Showcases for successful European legislation

Starting in 2002, regulations and legislative amendments in Germany focused on the non-smoker protection with several measures to reduce exposure to secondhand tobacco smoke (SHS). The present work aimed to evaluate the relationship between polycyclic aromatic hydrocarbons (PAHs) and SHS exposure and to determine to which extent enforced non-smoking regulations and smoking bans affected the exposure of the non-smoking population in Germany since their implementation in the early 2000s until today. For this purpose, cotinine and selected monohydroxylated PAHs (OH-PAHs) were analyzed by means of (UP)LC-MS/MS in 510 24-h-urine samples of the Environmental Specimen Bank collected over a time span of 24 years from 1995 to 2019. Median urinary cotinine levels were found to steadily and significantly decline by 82% from 1995 to 2019. A significant decrease of urinary 3-hydroxybenzo[a]pyrene (19%), 1-OH-pyrene (39%), 1-naphthol (66%), 1- (17%), 2- (25%), and 3-OH-phenanthrene (22%) was also observed throughout the same time span. The decline in urinary levels of cotinine and several OH-PAHs can most likely be attributed to smoking bans and regulations limiting SHS and PAH exposure. This study therefore emphasizes the relevance of human biomonitoring to investigate the exposure of humans to chemicals of concern, assess the effectiveness of regulatory measures, and help policies to enforce provisions to protect public health.

Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity

The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.

Determination of phytotoxicity and cytogenotoxicity due to exposure to particles originating from sugarcane burning using test systems Lactuca sativa L. and Allium cepa L

Sugarcane straw burning generates particulate matter with complex composition resulting in atmosphere pollution. Sugarcane straw sugarcane burning particles (PSSB) contain several chemical compounds that were previously identified to be associated with carcinogenic and mutagenic processes. The aim of the present study was to extract PSSB under lab conditions and subsequently determine phyto- and cytogenotoxicity of these particles using Lactuca sativa L. and Allium cepa L. bioassays. Seeds of lettuce var. Cinderela and onion cv. Vale-Ouro IPA-11 were germinated in Petri dishes containing different concentrations of PSSB at 25, 50, 100, 200 or 300 mg/ml as well as control for 72 hr. Seed germination of lettuce was inhibited by PSSB, in a concentration-dependent manner, accompanied by decreased root growth, suggesting phytotoxic effects. Further, reduction of mitotic index and high number of chromosomal alterations in onion of meristematics cells indicated a cytogenotoxic action attributed to PSSB. Although the chemical composition of PSSB in question has not been determined, the phyto- and cytogenotoxic effects may be linked to the possible presence of polycyclic aromatic hydrocarbons (PAHs), which are were identified as the main constituents of particulate matter resulting from burning of sugarcane straw, in addition to exerting adverse biological effects that might result in mutations and cancer. Data demonstrated that the use of plants bioassays might be an important tool for biomonitoring air quality.

Organic compound and particle emissions of additive manufacturing with photopolymer resins and chemical outgassing of manufactured resin products

Photopolymer resins are applied at an increasing rate in additive manufacturing (AM) industry as vat photopolymerization (VP) and material jetting (MJ) methods gain more popularity. The aim of this study was to measure volatile organic compound (VOC), carbonyl compound, ultrafine particle (UFP), and particulate matter (PM₁₀) air concentrations emitted in 3D printer operations. Individual chemicals were identified when multiple photopolymer resin feedstocks were used in various VP and MJ printers. The size distributions of UFPs, and indoor air parameters were also monitored. Finally, the VOC outgassing of the cured resin materials was determined over 84 days. The data demonstrated that 3D printer operators were exposed to low concentrations of airborne exposure agents as follows: average concentrations of VOCs were between 41 and 87 µg/m³, UFP number levels ranged between 0.19 and 3.62 × 10³ number/cm³; however, no impact was detected on air parameters or PM₁₀ concentrations. A majority of the UFPs existed in the 10-45 nm size range. The identified compounds included hazardous species included sensitizing acrylates and carcinogenic formaldehyde. The outgassed products included similar compounds that were encountered during the AM processes, and post-processing solvents. Products heated to 37°C emitted 1.4‒2.9-fold more VOCs than at room temperature. Total emissions were reduced by 84‒96% after 28 days roughly from 3000-14000 to 100-1000 µg/m²/hr. In conclusion, resin printer operators are exposed to low concentrations of hazardous emissions, which might result in adverse health outcomes during prolonged exposure. Manufactured resin products are suggested to be stored for 4 weeks after their production to reduce potential consumer VOC hazards.

Effects of Urban Green Space on Cardiovascular and Respiratory Biomarkers in Chinese Adults: Panel Study Using Digital Tracking Devices

Background

The health benefits of urban green space have been widely reported in the literature; however, the biological mechanisms remain unexplored, and a causal relationship cannot be established between green space exposure and cardiorespiratory health.

Objective

Our aim was to conduct a panel study using personal tracking devices to continuously collect individual exposure data from healthy Chinese adults aged 50 to 64 years living in Hong Kong.

Methods

A panel of cardiorespiratory biomarkers was tested each week for a period of 5 consecutive weeks. Data on weekly exposure to green space, air pollution, and the physical activities of individual participants were collected by personal tracking devices. The effects of green space exposure measured by the normalized difference vegetation index (NDVI) at buffer zones of 100, 250, and 500 meters on a panel of cardiorespiratory biomarkers were estimated by a generalized linear mixed-effects model, with adjustment for confounding variables of sociodemographic characteristics, exposure to air pollutants and noise, exercise, and nutrient intake.

Results

A total of 39 participants (mean age 56.4 years, range 50-63 years) were recruited and followed up for 5 consecutive weeks. After adjustment for sex, income, occupation, physical activities, dietary intake, noise, and air pollution, significant negative associations with the NDVI for the 250-meter buffer zone were found in total cholesterol (–21.6% per IQR increase in NDVI, 95% CI –32.7% to –10.6%), low-density lipoprotein (–14.9%, 95% CI –23.4% to –6.4%), glucose (–11.2%, 95% CI –21.9% to –0.5%), and high-sensitivity C-reactive protein (–41.3%, 95% CI –81.7% to –0.9%). Similar effect estimates were found for the 100-meter and 250-meter buffer zones. After adjustment for multiple testing, the effect estimates of glucose and high-sensitivity C-reactive protein were no longer significant.

Conclusions

The health benefits of green space can be found in some metabolic and inflammatory biomarkers. Further studies are warranted to establish the causal relationship between green space and cardiorespiratory health.

Individual exposure to urban air pollution and its correlation with placental angiogenic markers in the first trimester of pregnancy, in São Paulo, Brazil

Pollution of the atmosphere is known that may lead to adverse obstetric outcomes, including fetal growth restriction, gestational hypertension, and preeclampsia. Such disorders are correlated with imbalances in angiogenic factors, which may also be involved in the pathological mechanism as the pollutants impact placental and maternal physiology. In the first trimester of gestation, this study assessed the outcomes of personal maternal short period exposure to air pollution on soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PLGF) of pregnant women blood concentrations. This was a cross-sectional study, held in the city of São Paulo, Brazil, and conducted with low-risk pregnant women, who carried personal passive nitrogen dioxide (NO2) and ozone (O3) monitors for about a few days preceding the ultrasound evaluation, and on this day, the venous blood sample was collected to measure the angiogenic factors sFlt1 and PLGF and their ratio (sFlt1/PLGF) by enzyme-linked immunosorbent assay (ELISA). By means of multiple regression models, the effect of the studied pollutants on the log-transformed concentrations of the angiogenic factors was evaluated. One hundred thirty-one patients were included. The log of the sFlt1/PLGF ratio increased with rising NO2 levels (p = 0.021 and beta = 0.206), and the log of the PLGF concentration showed a negative correlation with NO2 (p = 0.008 and beta = - 0.234). NO2, an indicator of the levels of primary air pollutants, presented significant positive correlation with an increased sFlt1/PLGF ratio and diminished PLGF levels, which may reflect an antiangiogenic state generated by air pollution exposure.

Cardiovascular effects of air pollution: current evidence from animal and human studies

Air pollution is a global health concern. Particulate matter (PM)_2.5, a component of ambient air pollution, has been identified by the World Health Organization as one of the pollutants that poses the greatest threat to public health. Cardiovascular health effects have been extensively documented, and these effects are still being researched to provide an overview of recent literature regarding air pollution-associated cardiovascular morbidity and mortality in humans. Additionally, potential mechanisms through which air pollutants affect the cardiovascular system are discussed based on human and additional animal studies. We used the strategy of a narrative review to summarize the scientific literature of studies that were published in the past 7 yr. Searches were carried out on PubMed and Web of Science using predefined search queries. We obtained an initial set of 800 publications that were filtered to 78 publications that were relevant to include in this review. Analysis of the literature showed significant associations between air pollution, especially PM_2.5, and the risk of elevated blood pressure (BP), acute coronary syndrome, myocardial infarction (MI), cardiac arrhythmia, and heart failure (HF). Prominent mechanisms that underlie the adverse effects of air pollution include oxidative stress, systemic inflammation, endothelial dysfunction, autonomic imbalance, and thrombogenicity. The current review underscores the relevance of air pollution as a global health concern that affects cardiovascular health. More rigorous standards are needed to reduce the cardiovascular disease burden imposed by air pollution. Continued research on the health impact of air pollution is needed to provide further insight.

Use of Untargeted Metabolomics to Explore the Air Pollution-Related Disease Continuum

PURPOSE OF REVIEW

The purpose of this review is to summarize the application of untargeted metabolomics to identify the perturbation of metabolites or metabolic pathways associated with air pollutant exposures.

RECENT FINDINGS

Twenty-three studies were included in this review, in adults, children, or pregnant women. The most commonly measured air pollutant is particulate matter smaller than 2.5 μm. Size-fractioned particles, particle chemical species, gas pollutants, or organic compounds were also investigated. The reviewed studies used a wide range of air pollution measurement techniques and metabolomics analyses. Identified metabolites were primarily related to oxidative stress and inflammatory responses, and a few were related to the alterations of steroid metabolic pathways. The observed metabolic perturbations can differ by disease status, sex, and age. Air pollution-related metabolic changes were also associated with health outcomes in some studies. Our review shows that air pollutant exposures are associated with metabolic pathways primarily related to oxidative stress, inflammation, as assessed through untargeted metabolomics in 23 studies. More metabolomic studies with larger sample sizes are needed to identify air pollution components most responsible for adverse health effects, elaborate on mechanisms for subpopulation susceptibility, and link air pollution exposure to specific adverse health effects.

Atmospheric fine particulate matter and epithelial mesenchymal transition in pulmonary cells: state of the art and critical review of the in vitro studies

Exposure to fine particulate matter (PM_2.5) has been associated with several diseases including asthma, chronic obstructive pulmonary disease (COPD) and lung cancer. Mechanisms such as oxidative stress and inflammation are well-documented and are considered as the starting point of some of the pathological responses. However, a number of studies also focused on epithelial-mesenchymal transition (EMT), which is a biological process involved in fibrotic diseases and cancer progression notably via metastasis induction. Up until now, EMT was widely reported in vivo and in vitro in various cell types but investigations dealing with in vitro studies of PM_2.5 induced EMT in pulmonary cells are limited. Further, few investigations combined the necessary endpoints for validation of the EMT state in cells: such as expression of several surface, cytoskeleton or extracellular matrix biomarkers and activation of transcription markers and epigenetic factors. Studies explored various cell types, cultured under differing conditions and exposed for various durations to different doses. Such unharmonized protocols (1) might introduce bias, (2) make difficult comparison of results and (3) preclude reaching a definitive conclusion regarding the ability of airborne PM_2.5 to induce EMT in pulmonary cells. Some questions remain, in particular the specific PM_2.5 components responsible for EMT triggering. The aim of this review is to examine the available PM_2.5 induced EMT in vitro studies on pulmonary cells with special emphasis on the critical parameters considered to carry out future research in this field. This clarification appears necessary for production of reliable and comparable results.

In vivo and in vitro analysis of cytogenotoxicity in populations living in abnormal conditions from Santos-Sao Vicente estuary

The aim of the study was to evaluate cyto- and genotoxic effects in populations living in subnormal clusters in Santos São Vicente estuary. For in vivo study, samples of buccal mucosa and peripheral blood cells were collected. Micronucleus assay and single-cell gel (comet) assay were performed. For in vitro study, Chinese ovary hamster (CHO) cells were exposed to contaminated water. The results showed that people living in the contaminated estuary have increased DNA damage in oral mucosa and peripheral blood cells, as detected in the micronucleus and comet assays respectively. In addition, estuarine water was able to promote cytotoxicity at the highest concentrations, as well as decrease the number of cells in the G1 phase. In summary, our results indicate that water from the Santos-São Vicente estuary is capable of inducing cytogenotoxicity in mammalian cells in vivo and in vitro.

Analysis of urinary metabolites of polycyclic aromatic hydrocarbons and cotinine in pooled urine samples to determine the exposure to PAHs in an Australian population

Our previous biomonitoring study of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in a population in Australia found high levels of 1-naphthol, a metabolite of both naphthalene and carbaryl, in some adult samples. Here, we conducted a follow-up study to collect and analyse pooled urine samples, stratified by age and sex, from 2014 to 2017 using a GC-MS method. Geometric mean concentrations of 1-hydroxypyrene, the most common biomarker of PAH exposure, were 100 and 120 ng/L urine in 2014-2015 and 2016-2017, respectively. The concentrations of most OH-PAHs in this study except 1-naphthol are in line with those reported by biomonitoring programs in the US and Canada. In general, concentrations of OH-PAHs are lower in samples from small children (0-4 years) and school-aged children (5-14 years) compared with samples from the older age groups, except for some cases in the recent monitoring period. The concentrations of 1-naphthol in some adult samples of both sexes are very high, which is consistent with our previous findings. Such high concentrations of 1-naphthol together with the high 1-naphthol/2-naphthol ratio suggest potential exposure to the insecticide carbaryl in this population but other exposure sources and different rates of naphthalene metabolism should also be investigated.

Assessment of genotoxic effects on elderly populations exposed to high traffic areas: Results for supporting public health surveillance

In urban areas with intense vehicular traffic, particulate matter in suspension, especially the fraction of particles with ultra-fine diameter, has been regarded as the main problem of chronic diseases in susceptible populations, such as the elderly. This study aimed to determine the genotoxic effects of exposure to air pollution evaluating the association between the frequencies of micronuclei (MN) and binucleated (BN) cells in exfoliated oral mucosa cells of elderly population and exposure conditions, considering the influence of traffic and concentration of PM in different aerodynamic diameters. Traffic of passenger vehicles, heavy duty trucks and environmental concentrations of Particulate Matter were measured twice a day during 28 days before biological sampling of oral mucosa from 154 participants living in areas of distinct levels of urban traffic. Data from this study showed that the group of participants living near road traffic exhibited higher MN cell frequency, when compared to the other groups of subjects. In addition, a canonical correlation analysis between environmental and genotoxicity variables analysis revealed that high concentrations of the particulate matter were correlated with intense traffic and the genotoxicity in exfoliated oral cells.

Cardio-respiratory health effects of exposure to traffic-related air pollutants while exercising outdoors: A systematic review

Despite physical exercise provides numerous health benefits, outdoor exercisers are frequently exposed to traffic-related air pollutants (TRAP) known to be associated with respiratory and cardiovascular diseases. The aim of this systematic review was to investigate the effects of TRAP exposure, specifically particulate matter and nitrogen dioxide (NO₂), during outdoor exercise on cardio-respiratory health effects. Systematic database searches of PubMed, Web of Science, Scopus and Medline were performed by two researchers to identify peer-reviewed studies from 2000 to 2018. Combinations of keywords related to cardio-respiratory health effects, physical exercise and ambient air pollution were used. Thirteen studies were included, originating predominantly from European countries but also the American. They suggested that exercising in an environment with high TRAP exposure increases markers of respiratory and systemic inflammation, as well as, impairs the vascular function and increases artery pressure, when compared with an environment with low-TRAP exposure. In addition, the smaller particles appear to have the most severe health consequences compared with the larger coarse particles and NO₂. This study also provides evidence that specific groups of the population have enhanced susceptibility to adverse effects from particulate matter exposure while exercising. There is a need for more studies focused on the relationship between air pollution, physical exercise and health, as large societal benefits can be obtained from healthy environments that can promote outdoor physical exercise.

Relationship between fine particulate air pollution exposure and human adult life expectancy in Taiwan

Among the air pollutants, particulate matter with an aerodynamic diameter less than 2.5 um (PM_2.5) is of particular interest to environmental medicine as epidemiologic studies consistently reported that long-term exposure to PM_2.5 is associated with increased risk of premature death in adults. Life expectancy is a well-documented and important measure of overall public health policy. However, few investigators examined the relationship between PM_2.5 levels and adult life expectancy. In this Taiwan-wide study, county-level annual mean PM_2.5 concentrations data were collected concomitantly with potential confounding variables including demographic and socioeconomic status, as well as smoking prevalence. Subsequently, these PM_2.5 data were analyzed with respect to county-level adult life expectancy data for the period 2010 to 2017. Linear regression was used to determine the relationship between PM_2.5 and life expectancy in adults. Residents residing in the counties characterized as containing higher levels of PM_2.5 exhibited significantly reduced life expectancy after controlling for potential confounders. For each 10 ug/m³ increase in PM_2.5 there was an estimated mean decrease in life expectancy in adults of 0.3 years. The results of this study shed light on the relationship between fine particulate air pollution exposure and risk to human health in Taiwan.

Fine particulate air pollution associated with increased risk of hospital admissions for hypertension in a tropical city, Kaohsiung, Taiwan

The aim of this study was to assess whether a correlation exists between fine particles (PM_2.5) levels and number of hospital admissions for hypertension in Kaohsiung, Taiwan. Hospital admission frequency and ambient air pollution data were obtained for Kaohsiung for 2009-2013. A time-stratified case-crossover method was used to estimate relative risk for hospital admissions, controlling for weather, day of the week, seasonality, and long-term time trends. Odds ratios and 95% confidence intervals were calculated for a 10 µg/m³ increment of PM_2.5 for lags from days 0 to 6. Data showed no significant associations between PM_2.5 levels and number of hypertension-related hospital admissions on warm days (>25°C). However, on cool days (<25°C), a significant positive association was found with frequency of hypertension admissions in the single-pollutant model (without adjusting for other pollutants) with a 10 µg/m³ rise in PM_2.5 on day of admission (lag 0) associated with a 12% increase in number of admissions for hypertension. In the two-pollutant model, the association of PM_2.5 with rate of hypertension hospitalizations remained significant after including SO₂ or O₃ on lag day 0. Data demonstrate that an association between short-term exposure to PM_2.5 and elevated risk of hypertension-related hospital admissions may exist in Kaohsiung, Taiwan, a tropical city.

Mapping Exposure to Multi-Pollutants Using Environmental Biomonitors-A Multi-Exposure Index

Atmosphere is a major pathway for transport and deposition of pollutants in the environment. In industrial areas, organic compounds are released or formed as by-products, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F's). Inorganic chemical elements, including lead and arsenic, are also part of the pollutants mixture, and even in low concentrations may potentially be toxic and carcinogenic. However, assessing the spatial pattern of their deposition is difficult due to high spatial and temporal heterogeneity. Lichens have been used as biomonitors of atmospheric deposition, because these organisms encompass greater spatial detail than air monitoring stations and provide an integration of overall pollution. Based upon the ability of lichens to concentrate pollutants such as PCDD/F and chemical elements, the main objectives of this study were to develop a new semi-quantitative multi-pollutant toxicity exposure index (TEQ-like), derived from risk estimates, in an attempt to correlate several atmospheric pollutants to human exposure levels. The actual pollutant concentrations were measured in the environment, from biomonitors (organisms that integrate multi-pollutants), enabling interpolation and mapping of contaminant deposition within the region. Thus, the TEQ-like index provides a spatial representation not from absolute accumulation of the different pollutants, but from the accumulation weighted by their relative risk. The assessment of environmental human exposure to multi-pollutants through atmospheric deposition may be applied to industries to improve mitigation processes or to health stakeholders to target populations for a comprehensive risk assessment, epidemiological studies, and health recommendations.

Effects of Occupational Silica Exposure on OXIDATIVE Stress and Immune System Parameters in Ceramic Workers in TURKEY

Silica is the second most common element after oxygen, and therefore, exposures to crystalline silica dust occur in a large variety of occupations such as metal foundries, constructions, and ceramic, quarry, and pottery industries. Since crystalline silica exposure has been linked with silicosis, lung cancer, and other pulmonary diseases, adverse effect attributed to this element has be a cause for concern worldwide. Silica dust exposure in workers is still considered to be important health problem especially in developing countries. The aim of the study was to investigate the effects of occupational silica exposure on oxidative stress parameters including the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and levels of total glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) as well as immune system parameters such as interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, and IL-10 and tumor necrosis factor (TNF)-α in Turkish ceramic workers. In this study, nearly 50% of Turkish ceramic workers were diagnosed with silicosis. Eighty-four percent of these silicotic workers were found to present with profusion category 1 silicosis, whereas controls (n = 81) all displayed normal chest radiographs. Data demonstrated a significant decrease in levels of GSH and activities of CAT, SOD, and GPx, but a significant increase in MDA levels and activity of GR in all workers. Further, workers possessed significantly higher levels of IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, and TNF-α. These observations suggest that ceramic workers may have impaired antioxidant/oxidant status and activated immune system indicative of inflammatory responses.

Wood smoke exposure of Portuguese wildland firefighters: DNA and oxidative damage evaluation

Portugal is among the European Union countries most devastated by forest fires each year. In the last three decades, more than 3.8 million hectares of forest were burned. Wildland firefighters are exposed to a variety of hazards, including many toxic combustion products that may lead to deleterious health effects. Epidemiological studies showed a positive association between firefighting and several chronic diseases, including cancer. Results from biomonitoring studies in firefighters, particularly concerning genotoxicity evaluation, constitute a valuable tool for investigating important occupational hazards. Thus, the aim of this study was to assess genotoxicity in a group of wildland firefighters using the comet assay for DNA damage and oxidative stress. Both parameters were increased in firefighters compared to controls, but significance was only found for basal DNA damage. No significant influence was found regarding major confounding variables on the genotoxic endpoints studied, with the exception of age. Data obtained provide preliminary information on human health effects of wildland firefighting exposure at genetic and molecular levels. These findings may also provide new important data to serve as public awareness to the potential adverse health risks involving wildland firefighting. Implementation of security and hygiene measures in this sector as well as good practices campaigns may be crucial to decrease risk.

Short-Term Exposure to Urban Air Pollution and Influences on Placental Vascularization Indexes

BACKGROUND

It has been widely demonstrated that air pollution can affect human health and that certain pollutant gases lead to adverse obstetric outcomes, such as preeclampsia and fetal growth restriction.

OBJECTIVES

We evaluated the influence of individual maternal exposure to air pollution on placental volume and vascularization evaluated in the first trimester of pregnancy.

METHODS

This was a cross-sectional study on low-risk pregnant women living in São Paulo, Brazil. The women carried passive personal NO₂ and O₃ monitors in the week preceding evaluation. We employed the virtual organ computer-aided analysis (VOCAL) technique using three-dimensional power Doppler ultrasound to evaluate placental volume and placental vascular indexes [vascularization index (VI), flow index (FI), and vascularization flow index (VFI)]. We analyzed the influence of pollutant levels on log-transformed placental vascularization and volume using multiple regression models.

RESULTS

We evaluated 229 patients. Increased NO₂ levels had a significant negative association with log of VI (p = 0.020 and beta = -0.153) and VFI (p = 0.024 and beta = -0.151). NO₂ and O₃ had no influence on the log of placental volume or FI.

CONCLUSIONS

NO₂, an estimator of primary air pollutants, was significantly associated with diminished VI and VFI in the first trimester of pregnancy.

Particulate matter-mediated release of long pentraxin 3 (PTX3) and vascular endothelial growth factor (VEGF) in vitro: Limited importance of endotoxin and organic content

Exposure to particulate matter (PM) is associated with adverse health effects, but it is still relatively unknown which role PM sources and physicochemical properties play in the observed effects. It was postulated that PM in vitro induces release of long pentraxin 3 (PTX3) and vascular endothelial growth factor (VEGF) and that endotoxin and organic compounds present in the PM regulate this release. A contact coculture of THP-1 human leukemia monocytes and A549 human adenocarcinoma alveolar pneumocytes was exposed to PM from Traffic, Wood, Diesel, and Quartz (10-40 µg/cm²) for 12-64 h to determine release of PTX3 and VEGF. The role of endotoxin and the organic fraction in the mediator release was assessed using polymyxin B sulfate and organic extracts, respectively. Finally, antagonists were used to investigate whether the early proinflammatory cytokines interleukin (IL)-1 and tumor necrosis factor (TNF)-α affected the PTX3 and VEGF release. All PM samples induced a time-dependent release of both PTX3 and VEGF. Traffic mediated the greatest release of PTX3, whereas Wood and Diesel were more potent inducers of VEGF. The endotoxin content did not markedly affect release of either mediator, while the organic fraction exerted no significant effect on VEGF release and limited influence on PTX3 release. In addition, the IL-1 and TNF-α agonists affected PTX3 release more strongly than VEGF release. In conclusion, the current data show a limited impact of endotoxin and organic compounds on PTX3 and VEGF release. Further, the observed differences in response patterns may point toward differential regulation of PM-mediated release of PTX3 and VEGF.

Linking physiological parameters to perturbations in the human exposome: Environmental exposures modify blood pressure and lung function via inflammatory cytokine pathway

Human biomonitoring is an indispensable tool for evaluating the systemic effects derived from external stressors including environmental pollutants, chemicals from consumer products, and pharmaceuticals. The aim of this study was to explore consequences of environmental exposures to diesel exhaust (DE) and ozone (O₃) and ultimately to interpret these parameters from the perspective of in vitro to in vivo extrapolation. In particular, the objective was to use cytokine expression at the cellular level as a biomarker for physiological systemic responses such as blood pressure and lung function at the systemic level. The values obtained could ultimately link in vivo behavior to simpler in vitro experiments where cytokines are a measured parameter. Human exposures to combinations of DE and O₃ and the response correlations between forced exhaled volume in 1 second (FEV₁), forced vital capacity (FVC), systolic and diastolic blood pressure (SBP and DBP, respectively), and 10 inflammatory cytokines in blood (interleukins 1β, 2, 4, 5, 8, 10, 12p70 and 13, IFN-γ, and TNF-α) were determined in 15 healthy human volunteers. Results across all exposures revealed that certain individuals displayed greater inflammatory responses compared to the group and, generally, there was more between-person variation in the responses. Evidence indicates that individuals are more stable within themselves and are more likely to exhibit responses independent of one another. Data suggest that in vitro findings may ultimately be implemented to elucidate underlying adverse outcome pathways (AOP) for linking high-throughput toxicity tests to physiological in vivo responses. Further, this investigation supports assessing subjects based upon individual responses as a complement to standard longitudinal (pre vs. post) intervention grouping strategies. Ultimately, it may become possible to predict a physiological (systemic) response based upon cellular-level (in vitro) observations.

Fine particulate matter (PM2.5) enhances allergic sensitization in BALB/c mice

Ambient particulate matter (PM), a component of air pollution, exacerbates airway inflammation and hyperreactivity in asthmatic patients. Studies showed that PM possesses adjuvant-like properties that enhance the allergic inflammatory response; however, the mechanism (or mechanisms) by which PM enhances the allergic response remains to be determined. The aim of this study was to assess how exposure to fine PM collected from Sacramento, CA, shapes the allergic airway immune response in BALB/c mice undergoing sensitization and challenge with ovalbumin (OVA). Eight-week-old BALB/c male mice were sensitized/challenged with phosphate-buffered saline (PBS/PBS; n = 6), PM/PBS (n = 6), OVA/OVA (n = 6), or OVA + PM/OVA (n = 6). Lung tissue, bronchoalveolar lavage fluid (BALF), and plasma were analyzed for cellular inflammation, cytokines, immunoglobulin E, and heme oxygenase-1 (HO-1) expression. Mice in the OVA + PM/OVA group displayed significantly increased airway inflammation compared to OVA/OVA animals. Total cells, macrophages, and eosinophils recovered in BALF were significantly elevated in the OVA + PM/OVA compared to OVA/OVA group. Histopathological grading indicated that OVA + PM/OVA treatment induced significant inflammation compared to OVA/OVA. Both immunoglobulin (Ig) E and tumor necrosis factor (TNF) α levels were significantly increased in OVA/OVA and OVA + PM /OVA groups compared to PBS/PBS control. The number of HO-1 positive alveolar macrophages was significantly elevated in lungs of mice treated with OVA + PM /OVA compared to OVA/OVA. Our findings suggest that fine PM enhances allergic inflammatory response in pulmonary tissue through mechanisms involving increased oxidative stress.

Short-term effects of fine particulate air pollution on hospital admissions for hypertension: A time-stratified case-crossover study in Taipei

This study was undertaken to determine whether there was a correlation between fine particle (PM_2.5) levels and hospital admissions for hypertension in Taipei, Taiwan. Hospital admissions for hypertension and ambient air pollution data for Taipei were obtained for the period from 2009 to 2013. The relative risk of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single pollutant model (without adjustment for other pollutants), the risk of hospital admissions for hypertension was estimated to increase by 12% on warm days (>23°C) and 2% on cool days (<23°C), respectively. There was no indication of an association between levels of PM_2.5 and risk of hospital admissions for hypertension. In two-pollutant model, PM_2.5 remained nonsignificant after inclusion of any of the other air pollutants (SO₂, NO₂, CO, or O₃) both on warm and cool days, but a numerically greater response was seen on warm days. Data thus indicate that in Taipei, hospital admissions for hypertension occur as a consequence of factors not related to ambient air exposure.

Nanoparticles-induced apoptosis of human airway epithelium is mediated by proNGF/p75NTR signaling

Environmental and occupational exposures to respirable ultrafine fractions of particulate matter (PM) have been implicated in the initiation and exacerbation of lung diseases. However, the precise mechanisms underlying production of cell damage and death attributed to nanoparticles (NP) on human airway epithelium are not fully understood. This study examined the role of neurotrophic pathways in NP-induced airway toxicity. Size and agglomeration of TiO₂ nanoparticles (TiO₂-NP) and fine (TiO₂-FP) particles were measured by dynamic light scattering. Expression and signaling of key neurotrophic factors and receptors were assessed by real-time polymerase chain reaction, flow cytometry, immunostaining, and Western blot in various respiratory epithelial cells after exposure to TiO₂-NP or TiO₂-FP. Particle-induced cell death was measured by flow cytometry after annexin V/propidium iodide staining. The role of neurotrophin-dependent apoptotic pathways was analyzed with specific blocking antibodies or siRNAs. Exposure of human epithelial cells to TiO₂-NP enhanced interleukin (IL)-1α synthesis, as well as nerve growth factor (NGF) gene expression and protein levels, specifically the precursor form (proNGF). TiO₂-NP exposure also increased expression of p75^NRF receptor genes. These neurotropic factor and receptor responses were stimulated by IL-1α and abolished by its specific receptor antagonist (IL-1-ra). TiO₂-NP also increased JNK phosphorylation and apoptosis, which was prevented by anti-p75^NRF or NGFsiRNA. Data demonstrated that TiO₂-NP exerted adverse effects in the respiratory tract by inducing unbalanced overexpression of immature neurotrophins, which led to apoptotic death of epithelial cells signaled through the death receptor p75^NTR. This may result in airway inflammation and hyperreactivity after exposure to TiO₂-NP.

Tetrachlorobenzoquinone exhibits neurotoxicity by inducing inflammatory responses through ROS-mediated IKK/IκB/NF-κB signaling

Tetrachlorobenzoquinone (TCBQ) is a joint metabolite of persistent organic pollutants (POPs), hexachlorobenzene (HCB) and pentachlorophenol (PCP). Previous studies have been reported that TCBQ contributes to acute hepatic damage due to its pro-oxidative nature. In the current study, TCBQ showed the highest capacity on the cytotoxicity, ROS formation and inflammatory cytokines release among four compounds, i.e., HCB, PCP, tetrachlorohydroquinone (TCHQ, reduced form of TCBQ) and TCBQ, in PC 12 cells. Further mechanistic study illustrated TCBQ activates nuclear factor-kappa B (NF-κB) signaling. The activation of NF-κB was identified by measuring the protein expressions of inhibitor of nuclear factor kappa-B kinase (IKK) α/β, p-IKKα/β, an inhibitor of NF-κB (IκB) α, p-IκBα, NF-κB (p65) and p-p65. The translocation of NF-κB was assessed by Western blotting of p65 in nuclear/cytosolic fractions, electrophoretic mobility shift assay (EMSA) and luciferase reporter gene assay. In addition, TCBQ significantly induced protein and mRNA expressions of inflammatory cytokines and mediators, such as interleukin-1 beta (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and the production of nitric oxide (NO) and prostaglandin E2 (PGE2). Pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor inhibited these effects efficiently, further suggested TCBQ-induced inflammatory responses involve NF-κB signaling. Moreover, antioxidants, i.e., N-acetyl-l-cysteine (NAC), Vitamin E and curcumin, ameliorated TCBQ-induced ROS generation as well as the activation of NF-κB, which implied that ROS serve as the upstream molecule of NF-κB signaling. In summary, TCBQ exhibits a neurotoxic effect by inducing oxidative stress-mediated inflammatory responses via the activation of IKK/IκB/NF-κB pathway in PC12 cells.