Black carbon exposures, blood pressure, and interactions with single nucleotide polymorphisms in MicroRNA processing genes

A genome-wide by PM10 exposure interaction study for blood pressure in Korean adults

Blood pressure (BP) is a typical complex trait, and the genetic susceptibility of individuals to changes in BP induced by air pollution exposure is different. Although interactions of exposure to air pollutants with several candidate genes have been identified, genome-wide interaction studies (GWISs) are needed to understand the association between them with BP. Therefore, we aimed to discover the unique genetic loci for BP that interact with exposure to air pollutants in Korean adults. We ultimately included 1868 participants in the discovery step and classified them into groups of those with low-to-moderate exposure and high exposure to average annual concentration of particulate matter with an aerodynamic diameter ≤ 10 μm (PM10). Because none of the single nucleotide polymorphisms (SNPs) achieved a genome-wide level of significance of pint < 5 × 10-8 for either systolic BP (SBP) or diastolic BP (DBP), we considered the top 10 ranking SNPs for each BP trait. To validate these suggestive SNPs, we finally selected six genetic variants for SBP and five variants for DBP, respectively. In a replication result for SBP, only one SNP (rs12914147) located in an intergenic region of the NR2F2 showed a significant interaction. We also identified several genetic susceptibility loci (e.g., CHST11, TEK, and ITGA1) implicated in candidate mechanisms such as inflammation and oxidative stress in the discovery step, although their interaction effects were not replicated. Our study reports the first GWIS finding to our knowledge, and the association between exposure to PM10 and BP levels may be determined in part by several newly discovered genetic suggestive loci, including NR2F2.

Acute ambulatory blood pressure response to short-term black carbon exposure: The MobiliSense sensor-based study

Documented relationships between black carbon (BC) exposure and blood pressure (BP) have been inconsistent. Very few studies measured both BC exposure and ambulatory BP across the multiple daily environments visited in the general population, and none adjusted for personal noise exposure, a major confounder. Our study addresses these gaps by considering 245 adults living in the Grand Paris region. Personal exposure to BC was monitored for 2 days using AE51 microaethalometers. Ambulatory BP was measured every 30 min after waking up using Arteriograph 24 monitors (n = 6772). Mixed effect models with a random intercept at the individual level and time-autocorrelation structure adjusted for personal noise exposure were used to evaluate the associations between BC exposure (averaged from 5 min to 1 h before each BP measurement) and BP. To increase the robustness of findings, we eliminated confounding by unmeasured time-invariant personal variables, by modelling the associations with fixed-effect models. All models were adjusted for potential confounders and short-term time trends. Results from mixed models show that a 1-μg/m³ increase in 5-minute averaged BC exposure was associated with an increase of 0.57 mmHg in ambulatory systolic blood pressure (SBP) (95 % CI: 0.30, 0.83) and with an increase of 0.36 mmHg in diastolic blood pressure (DBP) (95 % CI: 0.14, 0.58). The slope of the exposure-response relationship gradually decreased for both SBP and DBP with the increase in the averaging period of BC exposure from 5 min to 1 h preceding each BP measurement. Findings from the fixed-effect models were consistent with these results. There was no effect modification by noise in the associations, across all exposure windows. We found evidence of a relationship between BC exposure and acute increase in ambulatory SBP and DBP after adjustment for personal noise exposure, with potential implications for the development of adverse cardiovascular outcomes.

Associations between APOL1 genetic variants and blood pressure in African American mothers and children from a U.S. pregnancy cohort: Modification by air pollution exposures

INTRODUCTION

Carriage of high-risk APOL1 genetic variants is associated with increased risks for kidney diseases in people of African descent. Less is known about the variants' associations with blood pressure or potential moderators.

METHODS

We investigated these associations in a pregnancy cohort of 556 women and 493 children identified as African American. Participants with two APOL1 risk alleles were defined as having the high-risk genotype. Blood pressure in both populations was measured at the child's 4-6 years visit. We fit multivariate linear and Poisson regressions and further adjusted for population stratification to estimate the APOL1-blood pressure associations. We also examined the associations modified by air pollution exposures (particulate matter ≤2.5 μ m in aerodynamic diameter [PM2.5] and nitrogen dioxide) and explored other moderators such as health conditions and behaviors.

RESULTS

Neither APOL1 risk alleles nor risk genotypes had a main effect on blood pressure in mothers or children. However, each 2-μg/m3 increase of four-year average PM2.5 was associated with a 16.3 (95%CI: 5.7, 26.9) mmHg higher diastolic blood pressure in mothers with the APOL1 high-risk genotype, while the estimated effect was much smaller in mothers with the low-risk genotype (i.e., 2.9 [95%CI: -3.1, 8.8] mmHg; Pinteraction = 0.01). Additionally, the associations of APOL1 risk alleles and the high-risk genotype with high blood pressure (i.e., SBP and/or DBP ≥ 90th percentile) were stronger in girls vs. boys (Pinteraction = 0.02 and 0.005, respectively).

CONCLUSION

This study sheds light on the distribution of high blood pressure by APOL1 genetic variants and informs regulatory policy to protect vulnerable population subgroups.

Long-term exposure to black carbon and mortality: A 28-year follow-up of the GAZEL cohort

BACKGROUND

The current evidence on health effects of long-term exposure to outdoor airborne black carbon (BC) exposure remains scarce.

OBJECTIVES

To examine the association between long-term exposure to BC and mortality in a large population-based French cohort, with 28 years of follow-up.

METHODS

Data from the GAZEL cohort were collected between 1989 and 2017. Land use regression model with temporal extrapolation wa used to estimate yearly BC and PM_2.5 exposure at the residential addresses from 1989 until censoring for 19,906 participants. Time-varying Cox models with attained age as time-scale was used to estimate the associations between BC and all-cause and cardiovascular mortality, after adjusting for individual and area-level covariates. To handle confounding by PM_2.5, we used the residual of BC regressed on PM_2.5 as an alternate exposure variable. For all-cause mortality, we also examined effect modification by sex, smoking status, BMI and fruit/vegetable intake.

RESULTS

The median of 20-year moving average of BC exposure was 2.02 10^-5/m in study population. We found significant associations between BC exposure and all-cause mortality (n = 2357) using both 20-year moving average of BC and residual of BC, with corresponding hazard ratios (HR) of 1.14 (95 %CI: 1.07-1.22) and 1.17 (95 %CI: 1.10-1.24) for an inter-quartile range (IQR) increase (0.86 10^-5/m for BC and 0.57 10^-5/m for residual of BC). We found a similar association between BC and cardiovascular mortality (n = 277) with a HR of 1.15 (95 %CI: 0.95-1.38). The dose-response relationship between BC and all-cause mortality was monotonic but nonlinear with a steeper slope at high BC levels. In addition, the effect of BC was higher among never-smokers and among those having fruit/vegetables less than twice a week.

CONCLUSIONS

There was a positive association between long-term exposure to BC and increased mortality risk, reinforcing the emerging evidence that BC is a harmful component of PM_2.5.

Short-Term Cumulative Exposure to Ambient Traffic-Related Black Carbon and Blood Pressure: MMDA Traffic Enforcers' Health Study

Exposure to traffic-related air pollution is linked with acute alterations in blood pressure (BP). We examined the cumulative short-term effect of black carbon (BC) exposure on systolic (SBP) and diastolic (DBP) BP and assessed effect modification by participant characteristics. SBP and DBP were repeatedly measured on 152 traffic enforcers. Using a linear mixed-effects model with random intercepts, quadratic (QCDL) and cubic (CCDL) constrained distributed lag models were fitted to estimate the cumulative effect of BC concentration on SBP and DBP during the 10 hours (daily exposure) and 7 days (weekly exposure) before the BP measurement. Ambient BC was related to increased BP with QCDL models. An interquartile range change in BC cumulative during the 7 days before the BP measurement was associated with increased BP (1.2% change in mean SBP, 95% confidence interval (CI), 0.1 to 2.3; and 0.5% change in mean DBP, 95% CI, −0.8 to 1.7). Moreover, the association between the 10-h cumulative BC exposure and SBP was stronger for female (4.0% change, 95% CI: 2.1–5.9) versus male and for obese (2.9% change, 95% CI: 1.0–4.8) vs. non-obese traffic enforcers. Short-term cumulative exposure to ambient traffic-related BC could bring about cardiovascular diseases through mechanisms involving increased BP.

Age and mitochondrial DNA copy number influence the association between outdoor temperature and cognitive function: Insights from the VA Normative Aging Study

BACKGROUND

General cognitive function deteriorates with aging, a change that has been linked to outdoor temperature. Older individuals have reduced ability to adapt to changes in outdoor temperature than younger people. However, to what extent short-term changes in outdoor temperature interact with mitochondria to affect cognition in older people has not yet been determined.

METHODS

Our study included 591 participants of the Normative Aging Study who underwent multiple examinations between 2000 and 2013. Cognitive function was evaluated via the Mini-Mental State Examination. Outdoor temperature was estimated at residential addresses 1 day before the examination using on a validated spatiotemporal temperature model. Mitochondrial DNA copy number (mtDNAcn) was determined using buffy coat samples.

RESULTS

We found an interaction between temperature, age, mtDNAcn, and cognition. In individuals 84 years of age or older, cooler temperature was associated with low cognition (odds ratio = 1.2; 95% confidence interval = 1.05, 1.35 for a 1°C decrease in temperature; P = 0.007). We found higher odds ratio per 1°C decrease in temperature among individuals with lower mtDNAcn (β3 = 0.12; 95% confidence interval = 0.01, 0.22; P interaction = 0.02).

CONCLUSIONS

Our findings, albeit potentially underpowered, suggest that older individuals may be more susceptible to the influence of short-term temperature exposure on cognition. Moreover, the level of mtDNAcn may also modify the association between temperature and cognitive function, indicating a possible role of these cellular elements in this relationship.

The association between short-term residential black carbon concentration on blood pressure in a general population sample

BACKGROUND

Exposure to black carbon indoors may be associated with blood pressure; however, evidence is limited to vulnerable subpopulations and highly exposed individuals. Our objective was to explore the relationship between indoor black carbon at various exposure windows on resting blood pressure in a general population sample.

METHODS

Black carbon was measured in the home of 76 individuals aged 10-71 in New Orleans, Louisiana. Exposure was measured every 1 minute for up to 120 hours using an AE51 microaethalometer. Systolic blood pressure and diastolic blood pressure were measured at the conclusion of exposure monitoring.

RESULTS

In adjusted models, at all exposure windows, increasing black carbon was associated with increased systolic blood pressure. The period 0-72 hours prior to blood pressure measurement showed the strongest effect; a 1 μg/m³ increase in black carbon was associated with a 7.55 mm Hg (P = .02) increase in systolic blood pressure. The relationship was stronger in participants reporting doctor-diagnosed hypertension (β = 6.47 vs β = 3.27). Black carbon was not associated with diastolic blood pressure.

CONCLUSION

Increasing black carbon concentration indoors is positively associated with increasing systolic blood pressure with the most relevant exposure window being 0-72 hours prior to blood pressure measurement. Individuals with hypertension may be a more susceptible population.

Genetic polymorphism in DGCR8 is associated with late onset of preeclampsia

Background

PE (preeclampsia) is a heterogeneous disorder with early onset PE (EOPE) and late onset PE (LOPE) subtypes. Associations between maternal miRNAs biosynthesis genes polymorphisms and risk of PE have been previously observed. However, the impact of polymorphisms in DGCR8 which is indispensable in miRNA maturing processing on the susceptibility to preeclampsia (PE) has not been elucidated yet. We, therefore, conducted a case-control study to evaluate the impact of polymorphisms in DGCR8 on the risk of EOPE and LOPE.

Methods

A total of 66 patients diagnosed with EOPE, 206 with LOPE and 330 healthy controls were recruited. Five SNPs in DGCR8 were genotyped including rs1558496, rs1640299, rs720012, rs720014, and rs9606241. Logistic regression was used to estimate the OR and the 95% CI for the associations.

Results

Increased risk of LOPE has been observed among patients with rs1640299 TG genotype (OR = 1.98 (95%CI: 1.38, 2.87), p = 2.32e-4) and rs720014 TC genotype (OR = 2.49 (95%CI: 1.72, 3.60), p = 1.40e-7). The DGCR8 rs1558496/ rs1640299/ rs720012/ rs720014/ rs9606241 haplotype T-G-A-C-A and T-G-A-C-G were associated with increased risk of LOPE (OR = 2.20 (95%CI: 1.49, 3.25), p = 5.90e-5, and 1.58 (95%CI: 1.06, 2.36), p = 0.024, respectively). And the haplotype T-T-G-T-A was associated with lower risk of LOPE (OR = 0.74 (95%CI: 0.58, 0.95), p = 0.018). These significant associations retained after false-positive discovery rate correction. However, none of the tested SNPs or haplotypes in DGCR8 gene is associated with risk of EOPE (p > 0.05).

Conclusions

Polymorphisms in DGCR8 might participate in the pathological process of preeclampsia. The rs1640299 T > G and rs720014 T > C polymorphisms are associated with late onset preeclampsia susceptibility.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0887-7) contains supplementary material, which is available to authorized users.

Oxidation Potential Reduction of Carbon Nanomaterials during Atmospheric-Relevant Aging: Role of Surface Coating

Carbon nanomaterials from various sources are the important component of PM_2.5 and have many adverse effects on human health. They are prone to interact with other pollutants and subsequently age, defined here as changes in chemical properties. In this work, we investigated the aging process of various carbon nanoparticle samples such as Special Black 4A, Printex U, single-walled carbon nanotubes, and hexane flame soot by ambient air and studied the evolution of their oxidation potential. We found that coatings of inorganic and organic species dominated the aging process of carbonaceous particles by ambient air. The amounts of disordered carbon and C-H functional groups of aged carbonaceous particles decreased during the aging process; meanwhile, the contents of sulfate and nitrate showed significant increases. In addition, the oxidation potential measured by the dithiothreitol assay remarkably declined as a function of aging time with ambient air evidently because of heterogeneous reactions between SO₂ and NO₂, as well as the coating with organic vapors. This work is important for understanding the oxidation potential changes of carbonaceous particles during atmospheric transport.

Synthesis of Harvard Environmental Protection Agency (EPA) Center studies on traffic-related particulate pollution and cardiovascular outcomes in the Greater Boston Area

The association between particulate pollution and cardiovascular morbidity and mortality is well established. While the cardiovascular effects of nationally regulated criteria pollutants (e.g., fine particulate matter [PM_2.5] and nitrogen dioxide) have been well documented, there are fewer studies on particulate pollutants that are more specific for traffic, such as black carbon (BC) and particle number (PN). In this paper, we synthesized studies conducted in the Greater Boston Area on cardiovascular health effects of traffic exposure, specifically defined by BC or PN exposure or proximity to major roadways. Large cohort studies demonstrate that exposure to traffic-related particles adversely affect cardiac autonomic function, increase systemic cytokine-mediated inflammation and pro-thrombotic activity, and elevate the risk of hypertension and ischemic stroke. Key patterns emerged when directly comparing studies with overlapping exposure metrics and population cohorts. Most notably, cardiovascular risk estimates of PN and BC exposures were larger in magnitude or more often statistically significant compared to those of PM_2.5 exposures. Across multiple exposure metrics (e.g., short-term vs. long-term; observed vs. modeled) and different population cohorts (e.g., elderly, individuals with co-morbidities, young healthy individuals), there is compelling evidence that BC and PN represent traffic-related particles that are especially harmful to cardiovascular health. Further research is needed to validate these findings in other geographic locations, characterize exposure errors associated with using monitored and modeled traffic pollutant levels, and elucidate pathophysiological mechanisms underlying the cardiovascular effects of traffic-related particulate pollutants. Implications: Traffic emissions are an important source of particles harmful to cardiovascular health. Traffic-related particles, specifically BC and PN, adversely affect cardiac autonomic function, increase systemic inflammation and thrombotic activity, elevate BP, and increase the risk of ischemic stroke. There is evidence that BC and PN are associated with greater cardiovascular risk compared to PM_2.5. Further research is needed to elucidate other health effects of traffic-related particles and assess the feasibility of regulating BC and PN or their regional and local sources.

Effectiveness of commercial face masks to reduce personal PM exposure

Cycling and walking are promoted as means of transportation which can contribute to the reduction of traffic pollution in urban areas. However, cyclists and pedestrians may be exposed to high concentrations of air pollutants due to their proximity to vehicle emissions. Commercial face mask respirators are widely used, in both developing and developed countries, as an individual protective measure against particle pollution. However scientific data on the efficacy of face mask respirators in reducing airborne particle exposure is limited. In this study, a custom experimental set-up was developed in order to measure the effectiveness of nine different respirators under real environmental conditions in terms of particle mass concentration below 2.5 μm (PM_2.5), particle number concentration (PNC), Lung Deposited Surface Area (LDSA) and Black Carbon concentration (BC). Face mask performances were assessed in a typical traffic affected urban background environment in the city of Barcelona under three different simulated breathing rates to investigate the influence of flow rate. Results showed a median face mask effectiveness for PM_2.5 equal to 48% in a range of 14-96%, 19% in a range of 6%-61% for BC concentration, 19% in a range of 4%-63% for PNC and 22% in a range of 5%-65% for LDSA. For each pollutant under investigation, the best performance was found always with the same mask (N7) although it is not the most expensive (in a range of price of 1 to 44, its cost was 20 euros), which has a filter on the entire surface except for the 2 exhalation valves where air cannot enter but just exit and shows a good fit on the dummy head.

The Role of MicroRNAs in Environmental Risk Factors, Noise-Induced Hearing Loss, and Mental Stress

SIGNIFICANCE

MicroRNAs (miRNAs) are important regulators of gene expression and define part of the epigenetic signature. Their influence on every realm of biomedicine is established and progressively increasing. The impact of environment on human health is enormous. Among environmental risk factors impinging on quality of life are those of chemical nature (toxic chemicals, heavy metals, pollutants, and pesticides) as well as those related to everyday life such as exposure to noise or mental and psychosocial stress. Recent Advances: This review elaborates on the relationship between miRNAs and these environmental risk factors.

CRITICAL ISSUES

The most relevant facts underlying the role of miRNAs in the response to these environmental stressors, including redox regulatory changes and oxidative stress, are highlighted and discussed. In the cases wherein miRNA mutations are relevant for this response, the pertinent literature is also reviewed.

FUTURE DIRECTIONS

We conclude that, even though in some cases important advances have been made regarding close correlations between specific miRNAs and biological responses to environmental risk factors, a need for prospective large-cohort studies is likely necessary to establish causative roles. Antioxid. Redox Signal. 28, 773-796.

Impacts of exposure to black carbon, elemental carbon, and ultrafine particles from indoor and outdoor sources on blood pressure in adults: A review of epidemiological evidence

INTRODUCTION

Ambient particulate air pollution is known to have detrimental effects on cardiovascular health but less is known about the specific effects of black carbon or elemental carbon (BC/EC) and ultrafine particles (UFP).

METHODS

We present a narrative review of the epidemiological evidence related to the impact of exposure to BC/EC and UFP on blood pressure in adults. We searched PubMed and EMBASE in September 2017, using a predefined search strategy. Abstracts were screened using predefined inclusion criteria. Data collection was completed using a standard data extraction form. We focused on main effect estimates for associations between short (≤7 days) and long-term exposures to BC/EC and UFP and systolic (SBP) and diastolic blood pressure (DBP). Effect estimates were rescaled to enable direct comparisons between studies.

RESULTS

Thirty publications were included in the review: 19 studies examined outdoor exposure to BC/EC, 11 examined outdoor UFP, three studies examined indoor BC and one study examined indoor UFP. In general, existing evidence supports a positive association between BC/EC and blood pressure. Evidence for outdoor UFP exposures were less clear as effect estimates were small in magnitude and confidence intervals often included the null.

CONCLUSIONS

Existing evidence supports a positive association between BC/EC and blood pressure in adults, whereas UFPs do not appear to have a meaningful impact on blood pressure.

Vascular and cardiac autonomic function and PM2.5 constituents among the elderly: A longitudinal study

BACKGROUND

Although epidemiologic studies have shown an association between the total mass of particulate matter <2.5μm in aerodynamic diameter (PM_2.5) and cardiovascular disease, few studies have examined PM_2.5 constituents associated with vascular and cardiac autonomic dysfunction.

METHODS

In this longitudinal study, we investigated the relationship between PM_2.5 constituents and blood pressure (BP), and markers of the autonomic nervous system. In 466 elderly subjects residing in communities in Seoul, Korea, we examined 16 constituents, seven sources, and total mass concentrations of PM_2.5. We measured the BP, heart rate (HR), and indices of heart rate variability (HRV), such as the standard deviation of normal-to-normal intervals (SDNN), square root of the mean squared differences of successive NN intervals (rMSSD), and two frequency-domain variables (low frequency [LF] and high frequency [HF]). We used linear mixed effects models to assess the association of PM_2.5 constituents and sources with cardiovascular markers.

RESULTS

BP, HR, and rMSSD were associated with concentration of total mass of PM_2.5. For each increase of the interquartile range in PM_2.5 constituents, systolic and diastolic BP, and HR increased by 2.1-3.3mmHg, 1.2-2.3mmHg, and 1.2-1.9bpm, respectively, while the rMSSD, LF, and HF decreased by 8.1-9.3%, 16.6%, and 20.4%, respectively. Particularly, elemental carbon, sulfate, ammonium, lead, and strontium in the PM_2.5 constituents and emissions from oil combustion and incineration were associated with increased BP, HR, and decreased HRV.

CONCLUSIONS

Our results suggest an association between specific PM_2.5 constituents and vascular and cardiac autonomic functions. These findings may provide supportive evidence for developing a pollution reduction plan to prevent cardiovascular diseases.

miRNA processing gene polymorphisms, blood DNA methylation age and long-term ambient PM2.5 exposure in elderly men

AIM

We tested whether genetic variation in miRNA processing genes modified the association of PM2.5 with DNA methylation (DNAm) age.

PATIENTS & METHODS

We conducted a repeated measures study based on 552 participants from the Normative Aging Study with multiple visits between 2000 and 2011 (n = 940 visits). Address-level 1-year PM2.5 exposures were estimated using the GEOS-chem model. DNAm-age and a panel of 14 SNPs in miRNA processing genes were measured from participant blood samples.

RESULTS & CONCLUSION

In fully adjusted linear mixed-effects models, having at least one copy of the minor rs4961280 [AGO2] allele was associated with a lower DNAm-age (β = -1.13; 95% CI: -2.26 to -0.002). However, the association of PM2.5 with DNAm-age was significantly (Pinteraction  = 0.01) weaker in homozygous carriers of the major rs4961280 [AGO2] allele (β = 0.38; 95% CI: -0.20 to 0.96) when compared with all other participants (β = 1.58; 95% CI: 0.76 to 2.39). Our results suggest that miRNA processing impacts DNAm-age relationships. Graphical abstract: miRNA processing AGO2 polymorphism (rs4961280) modifies the association of long-term ambient fine particle exposure with blood DNA methylation age [Formula: see text] The graph depicts lines from a fully adjusted linear regression model with fine particle exposure levels ranging from the tenth to the ninetieth percentile, all other continuous variables held constant at their means, and all other categorical variables held at their most frequent level.

Histone 3 modifications and blood pressure in the Beijing Truck Driver Air Pollution Study

CONTEXT

Histone modifications regulate gene expression; dysregulation has been linked with cardiovascular diseases. Associations between histone modification levels and blood pressure in humans are unclear.

OBJECTIVE

We examine the relationship between global histone concentrations and various markers of blood pressure.

MATERIALS AND METHODS

Using the Beijing Truck Driver Air Pollution Study, we investigated global peripheral white blood cell histone modifications (H3K9ac, H3K9me3, H3K27me3, and H3K36me3) associations with pre- and post-work measurements of systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP), and pulse pressure (PP) using multivariable mixed-effect models.

RESULTS

H3K9ac was negatively associated with pre-work SBP and MAP; H3K9me3 was negatively associated with pre-work SBP, DBP, and MAP; and H3K27me3 was negatively associated with pre-work SBP. Among office workers, H3K9me3 was negatively associated with pre-work SBP, DBP, and MAP. Among truck drivers, H3K9ac and H3K27me were negatively associated with pre-work SBP, and H3K27me3 was positively associated with post-work PP.

DISCUSSION AND CONCLUSION

Epigenome-wide H3K9ac, H3K9me3, and H3K27me3 were negatively associated with multiple pre-work blood pressure measures. These associations substantially changed during the day, suggesting an influence of daily activities. Blood-based histone modification biomarkers are potential candidates for studies requiring estimations of morning/pre-work blood pressure.

Comparison of lung damage in mice exposed to black carbon particles and 1,4-naphthoquinone coated black carbon particles

Black carbon (BC) is a key component of atmospheric particles and has a significant effect on human health. BC can provide reactive sites and surfaces thus absorb quinones which were primarily generated from fossil fuel combustion and/or atmospheric photochemical conversions of PAHs. Oxidation could change the characteristics of BC and increase its toxicity. The comparison of lung damage in mice exposed to BC and 1,4-NQ-coated BC (1,4NQ-BC) particles is investigated in this study. Mice which were intratracheally instilled with particles have a higher expression of IL-1β, IL-6 and IL-33 in bronchoalveolar lavage fluid (BALF). Also, the IL-6, IL-33 mRNA expression in the lung tissue of mice instilled with 1,4NQ-BC were higher than that of mice instilled with BC. The pathology results showed that the lung tissue of mice instilled with 1,4NQ-BC particles have much more inflammatory cells infiltration than that of mice treated with BC. It is believed that the MAPK and PI3K-AKT pathway might be involved in the 1,4NQ-BC particles caused lung damage. Results indicated that 1,4NQ-BC particles in the atmosphere may cause more damage to health.

Estimating Causal Effects of Local Air Pollution on Daily Deaths: Effect of Low Levels

BACKGROUND

Although many time-series studies have established associations of daily pollution variations with daily deaths, there are fewer at low concentrations, or focused on locally generated pollution, which is becoming more important as regulations reduce regional transport. Causal modeling approaches are also lacking.

OBJECTIVE

We used causal modeling to estimate the impact of local air pollution on mortality at low concentrations.

METHODS

Using an instrumental variable approach, we developed an instrument for variations in local pollution concentrations that is unlikely to be correlated with other causes of death, and examined its association with daily deaths in the Boston, Massachusetts, area. We combined height of the planetary boundary layer and wind speed, which affect concentrations of local emissions, to develop the instrument for particulate matter ≤ 2.5 μm (PM2.5), black carbon (BC), or nitrogen dioxide (NO2) variations that were independent of year, month, and temperature. We also used Granger causality to assess whether omitted variable confounding existed.

RESULTS

We estimated that an interquartile range increase in the instrument for local PM2.5 was associated with a 0.90% increase in daily deaths (95% CI: 0.25, 1.56). A similar result was found for BC, and a weaker association with NO2. The Granger test found no evidence of omitted variable confounding for the instrument. A separate test confirmed the instrument was not associated with mortality independent of pollution. Furthermore, the association remained when all days with PM2.5 concentrations > 30 μg/m3 were excluded from the analysis (0.84% increase in daily deaths; 95% CI: 0.19, 1.50).

CONCLUSIONS

We conclude that there is a causal association of local air pollution with daily deaths at concentrations below U.S. EPA standards. The estimated attributable risk in Boston exceeded 1,800 deaths during the study period, indicating that important public health benefits can follow from further control efforts. Citation: Schwartz J, Bind MA, Koutrakis P. 2017. Estimating causal effects of local air pollution on daily deaths: effect of low levels. Environ Health Perspect 125:23-29; http://dx.doi.org/10.1289/EHP232.

Quantile Regression Analysis of the Distributional Effects of Air Pollution on Blood Pressure, Heart Rate Variability, Blood Lipids, and Biomarkers of Inflammation in Elderly American Men: The Normative Aging Study

BACKGROUND

Previous studies have observed associations between air pollution and heart disease. Susceptibility to air pollution effects has been examined mostly with a test of effect modification, but little evidence is available whether air pollution distorts cardiovascular risk factor distribution.

OBJECTIVES

This paper aims to examine distributional and heterogeneous effects of air pollution on known cardiovascular biomarkers.

METHODS

A total of 1,112 men from the Normative Aging Study and residents of the greater Boston, Massachusetts, area with mean age of 69 years at baseline were included in this study during the period 1995-2013. We used quantile regression and random slope models to investigate distributional effects and heterogeneity in the traffic-related responses on blood pressure, heart rate variability, repolarization, lipids, and inflammation. We considered 28-day averaged exposure to particle number, PM2.5 black carbon, and PM2.5 mass concentrations (measured at a single monitor near the site of the study visits).

RESULTS

We observed some evidence suggesting distributional effects of traffic-related pollutants on systolic blood pressure, heart rate variability, corrected QT interval, low density lipoprotein (LDL) cholesterol, triglyceride, and intercellular adhesion molecule-1 (ICAM-1). For example, among participants with LDL cholesterol below 80 mg/dL, an interquartile range increase in PM2.5 black carbon exposure was associated with a 7-mg/dL (95% CI: 5, 10) increase in LDL cholesterol, while among subjects with LDL cholesterol levels close to 160 mg/dL, the same exposure was related to a 16-mg/dL (95% CI: 13, 20) increase in LDL cholesterol. We observed similar heterogeneous associations across low versus high percentiles of the LDL distribution for PM2.5 mass and particle number.

CONCLUSIONS

These results suggest that air pollution distorts the distribution of cardiovascular risk factors, and that, for several outcomes, effects may be greatest among individuals who are already at high risk.

CITATION

Bind MA, Peters A, Koutrakis P, Coull B, Vokonas P, Schwartz J. 2016. Quantile regression analysis of the distributional effects of air pollution on blood pressure, heart rate variability, blood lipids, and biomarkers of inflammation in elderly American men: the Normative Aging Study. Environ Health Perspect 124:1189-1198; http://dx.doi.org/10.1289/ehp.1510044.

Associations of air pollution exposure with blood pressure and heart rate variability are modified by oxidative stress genes: A repeated-measures panel among elderly urban residents

BACKGROUND

Oxidative stress has been suggested as a major cause of elevated blood pressure (BP) and reduced heart rate variability (HRV) due to air pollution. We hypothesized that the associations of air pollution exposure with BP and HRV are modified by oxidative stress gene polymorphisms.

METHODS

Between 2008 and 2010, we conducted up to 5 surveys of 547 elderly participants, measured their BP and HRV, and genotyped 47 single nucleotide polymorphisms (SNPs) in 18 oxidative stress genes. Linear mixed models were constructed to evaluate the associations of particulate matter ≤10 μm, nitrogen dioxide, and sulfur dioxide with BP and HRV, as well as the modifications of these associations by the genotyped SNPs.

RESULTS

Single-SNP analyses revealed interactions between air pollution and 15 SNPs (for BP) and 33 SNPs (for HRV) (all, P for interaction < 0.05). When we generated genetic risk scores for BP and HRV, using the SNPs with interactions in the single-SNP models, we found that associations of air pollution exposure with BP and HRV were modified by the genetic risk scores (P for interaction < 0.05).

CONCLUSIONS

These results strongly suggest that the associations of air pollution with BP and HRV are mediated by oxidative stress pathways.

MiRNA-Related Genetic Variations Associated with Radiotherapy-Induced Toxicities in Patients with Locally Advanced Non-Small Cell Lung Cancer

Severe radiation-induced toxicities limit treatment efficacy and compromise outcomes of lung cancer. We aimed to identify microRNA-related genetic variations as biomarkers for the prediction of radiotherapy-induced acute toxicities. We genotyped 233 SNPs (161 in microRNA binding site and 72 in processing gene) and analyzed their associations with pneumonitis and esophagitis in 167 stage III NSCLC patients received definitive radiation therapy. Sixteen and 11 SNPs were associated with esophagitis and pneumonitis, respectively. After multiple comparison correction, RPS6KB2:rs10274, SMO:rs1061280, SMO:rs1061285 remained significantly associated with esophagitis, while processing gene DGCR8:rs720014, DGCR8:rs3757, DGCR8:rs1633445 remained significantly associated with pneumonitis. Patients with the AA genotype of RPS6KB2:rs10274 had an 81% reduced risk of developing esophagitis (OR: 0.19, 95% CI: 0.07–0.51, p = 0.001, q = 0.06). Patients with the AG+GG genotype of SMO:rs1061280 had an 81% reduced risk of developing esophagitis (OR: 0.19, 95% CI: 0.07–0.53, p = 0.001, q = 0.06). Patients with the GG+GA genotype of DGCR8:rs720014 had a 3.54-fold increased risk of pneumonitis (OR: 3.54, 95% CI: 1.65–7.61, p <0.05, q <0.1). Significantly cumulative effects of the top SNPs were observed for both toxicities (P-trend <0.001). Using bioinformatics tools, we found that the genotype of rs10274 was associated with altered expression of the RPS6KB2 gene. Gene-based analysis showed DGCR8 (p = 0.010) and GEMIN4 (p = 0.039) were the top genes associated with the risk of developing pneumonitis. Our results provide strong evidence that microRNA-related genetic variations contribute to the development of radiotherapy-induced acute esophagitis and pneumonitis and could thus serve as biomarkers to help accurately predict radiotherapy-induced toxicity in NSCLC patients.

Long-term exposure to black carbon, cognition and single nucleotide polymorphisms in microRNA processing genes in older men

INTRODUCTION

Air pollution exposure has been linked to impaired cognitive aging, but little is known about biomarkers modifying this association. MicroRNAs (miRNAs) control gene expression and neuronal programming. miRNA levels vary due to single nucleotide polymorphisms (SNPs) in genes processing miRNAs from precursor molecules.

OBJECTIVES

To investigate whether SNPs in miRNA-processing genes are associated with cognition and modify the relationship between black carbon (BC), marker of traffic-related pollution, and cognitive functions.

METHODS

533 Normative Aging Study men (mean±SD 72±7years) were tested ≤4 times (mean=1.7 times) using seven cognitive tests between 1995 and 2007. We tested interactions of 16 miRNA-related SNPs with 1-year average BC from a validated land-use-regression model. We used covariate-adjusted logistic regression for low (≤25) Mini-Mental tate Examination (MMSE) and mixed-effect regression for a global cognitive score combining six other tests.

RESULTS

Global cognition was negatively associated with the homozygous minor variant of rs595961 AGO1 (-0.42SD; 95%CI: (-0.71, -0.13)) relative to the major variant. BC-MMSE association was stronger in heterozygous carriers of rs11077 XPO5 (OR=1.99; 95%CI: (1.39, 2.85)) and minor variant carriers of GEMIN4 rs2740348 (OR=1.34; 95%CI: (1.05, 1.7)), compared to their major variant. The BC-global-cognition association was stronger in heterozygous carriers of GEMIN4 rs4968104 (-0.10SD; 95%CI: (-0.18, -0.02)), and GEMIN4 rs910924 (-0.09SD; 95%CI: (-0.17, -0.02)) relative to the major variant. Blood miRNA expression analyses showed associations only of XPO5 rs11077 with miR-9 and miR-96.

CONCLUSIONS

Carriers of particular miRNA-processing SNPs had higher susceptibility to BC in BC-cognition associations, possibly due to influences on miRNA expression.

Use of the Adaptive LASSO Method to Identify PM2.5 Components Associated with Blood Pressure in Elderly Men: The Veterans Affairs Normative Aging Study

BACKGROUND

PM2.5 (particulate matter ≤ 2.5 μm) has been associated with adverse cardiovascular outcomes, but it is unclear whether specific PM2.5 components, particularly metals, may be responsible for cardiovascular effects.

OBJECTIVES

We aimed to determine which PM2.5 components are associated with blood pressure in a longitudinal cohort.

METHODS

We fit linear mixed-effects models with the adaptive LASSO penalty to longitudinal data from 718 elderly men in the Veterans Affairs Normative Aging Study, 1999-2010. We controlled for PM2.5 mass, age, body mass index, use of antihypertensive medication (ACE inhibitors, non-ophthalmic beta blockers, calcium channel blockers, diuretics, and angiotensin receptor antagonists), smoking status, alcohol intake, years of education, temperature, and season as fixed effects in the models, and additionally applied the adaptive LASSO method to select PM2.5 components associated with blood pressure. Final models were identified by the Bayesian Information Criterion (BIC).

RESULTS

For systolic blood pressure (SBP), nickel (Ni) and sodium (Na) were selected by the adaptive LASSO, whereas only Ni was selected for diastolic blood pressure (DBP). An interquartile range increase (2.5 ng/m3) in 7-day moving-average Ni was associated with 2.48-mmHg (95% CI: 1.45, 3.50 mmHg) increase in SBP and 2.22-mmHg (95% CI: 1.69, 2.75 mmHg) increase in DBP, respectively. Associations were comparable when the analysis was restricted to study visits with PM2.5 below the 75th percentile of the distribution (12 μg/m3).

CONCLUSIONS

Our study suggested that exposure to ambient Ni was associated with increased blood pressure independent of PM2.5 mass in our study population of elderly men. Further research is needed to confirm our findings, assess generalizability to other populations, and identify potential mechanisms for Ni effects.

CITATION

Dai L, Koutrakis P, Coull BA, Sparrow D, Vokonas PS, Schwartz JD. 2016. Use of the adaptive LASSO method to identify PM2.5 components associated with blood pressure in elderly men: the Veterans Affairs Normative Aging Study. Environ Health Perspect 124:120-125; http://dx.doi.org/10.1289/ehp.1409021.

Traffic-related air pollution and sleep in the Boston Area Community Health Survey

Little is known about environmental determinants of sleep. We investigated the association between black carbon (BC), a marker of traffic-related air pollution, and sleep measures among participants of the Boston Area Community Health Survey. We also sought to assess the impact of sociodemographic factors, health conditions, and season on associations. Residential 24-h BC was estimated from a validated land-use regression model for 3821 participants and averaged over 1-6 months and 1 year. Sleep measures included questionnaire-assessed sleep duration, sleep latency, and sleep apnea. Linear and logistic regression models controlling for confounders estimated the association between sleep measures and BC. Effect modification was tested with interaction terms. Main effects were not observed between BC and sleep measures. However, in stratified models, males experienced 0.23 h less sleep (95% CI: -0.42, -0.03) and those with low SES 0.25 h less sleep (95% CI: -0.48, -0.01) per IQR increase in annual BC (0.21 μg/m(3)). In blacks, sleep duration increased with annual BC (β=0.34 per IQR; 95% CI: 0.12, 0.57). Similar findings were observed for short sleep (≤5 h). BC was not associated with sleep apnea or sleep latency, however, long-term exposure may be associated with shorter sleep duration, particularly in men and those with low SES, and longer sleep duration in blacks.

MicroRNAs as regulators of airborne pollution-induced lung inflammation and carcinogenesis

The increasing incidence of pulmonary inflammation and lung cancer, as well as exacerbation of pre-existing chronic lung diseases by exposure to airborne pollutants, e.g., particulate matter and cigarette smoke, is becoming a major public health concern in the world. However, the exact mechanisms of pulmonary injury from exposure to these airborne insults have not been fully elucidated. Nevertheless, accumulating evidence suggests that microRNAs (miRNAs) may play a unique role in the regulation of airborne agent-induced lung inflammation and carcinogenesis. Since epigenetic modifications are heritable and reversible, this may provide a new insight into the relationship of miRNAs and environmental pollution-related lung disorders. The aim of this review was to update our existing knowledge regarding the mechanisms by which airborne pollutants altering miRNA profiles in the lung, specifically for cigarette smoke and airborne particulate matter, and the potential biological roles of miRNAs in the initiation of pulmonary inflammation and lung cancer, as well as the regulation of underlying genetic susceptibility to these environmental stressors.

Blood pressure changes in association with black carbon exposure in a panel of healthy adults are independent of retinal microcirculation

Exposure to ambient particulate matter and elevated blood pressure are risk factors for cardiovascular morbidity and mortality. Microvascular changes might be an important pathway in explaining the association between air pollution and blood pressure. The objective of the study was to evaluate the role of the retinal microcirculation in the association between black carbon (BC) exposure and blood pressure. We estimated subchronic BC exposure based on 1-week personal measurements (μ-Aethalometer, AethLabs) in 55 healthy nurses. Blood pressure and retinal microvasculature were measured on four different days (range: 2-4) during this week. Subchronic BC exposure averaged (± SD) 1334±631ng/m(3) and ranged from 338ng/m(3) to 3889ng/m(3). An increased exposure of 631ng/m(3) BC was associated with a 2.77mmHg (95% CI: 0.39 to 5.15, p=0.027) increase in systolic blood pressure, a 2.35mmHg (95% CI: 0.52 to 4.19, p=0.016) increase in diastolic blood pressure and with 5.65μm (95% CI: 1.33 to 9.96, p=0.014) increase in central retinal venular equivalent. Mediation analysis failed to reveal an effect of retinal microvasculature in the association between blood pressure and subchronic BC exposure. In conclusion, we found a positive association between blood pressure and subchronic black carbon exposure in healthy adults. This finding adds evidence to the association between black carbon exposure and cardiovascular health effects, with elevated blood pressure as a plausible intermediate effector. Our results suggest that the changes in a person's blood pressure as a result of subchronic black carbon exposure operate independently of the retinal microcirculation.

Exposure to traffic-related air pollution during physical activity and acute changes in blood pressure, autonomic and micro-vascular function in women: a cross-over study

Background

Traffic-related air pollution may contribute to cardiovascular morbidity. In urban areas, exposures during physical activity are of interest owing to increased breathing rates and close proximity to vehicle emissions.

Methods

We conducted a cross-over study among 53 healthy non-smoking women in Montreal, Canada during the summer of 2013. Women were exposed to traffic pollutants for 2-hours on three separate occasions during cycling on high and low-traffic routes as well as indoors. Personal air pollution exposures (PM_2.5, ultrafine particles (UFP), black carbon, NO₂, and O₃) were evaluated along each route and linear mixed-effects models with random subject intercepts were used to estimate the impact of air pollutants on acute changes in blood pressure, heart rate variability, and micro-vascular function in the hours immediately following exposure. Single and multi-pollutant models were examined and potential effect modification by mean regional air pollution concentrations (PM_2.5, NO₂, and O₃) was explored for the 24-hour and 5-day periods preceding exposure.

Results

In total, 143 exposure routes were completed. Each interquartile increase (10,850/cm³) in UFP exposure was associated with a 4.91% (95% CI: -9.31, -0.512) decrease in reactive hyperemia index (a measure of micro-vascular function) and each 24 ppb increase in O₃ exposure corresponded to a 2.49% (95% CI: 0.141, 4.84) increase in systolic blood pressure and a 3.26% (95% CI: 0.0117, 6.51) increase in diastolic blood pressure 3-hours after exposure. Personal exposure to PM_2.5 was associated with decreases in HRV measures reflecting parasympathetic modulation of the heart and regional PM_2.5 concentrations modified these relationships (p < 0.05). In particular, stronger inverse associations were observed when regional PM_2.5 was higher on the days prior to the study period. Regional PM_2.5 also modified the impact of personal O₃ on the standard deviation of normal to normal intervals (SDNN) (p < 0.05): a significant inverse relationship was observed when regional PM_2.5 was low prior to study periods and a significant positive relationship was observed when regional PM_2.5 was high.

Conclusion

Exposure to traffic pollution may contribute to acute changes in blood pressure, autonomic and micro-vascular function in women. Regional air pollution concentrations may modify the impact of these exposures on autonomic function.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0070-4) contains supplementary material, which is available to authorized users.

Long-term effects of traffic particles on lung function decline in the elderly

RATIONALE

Few studies have been performed on air pollution effects on lung function in the elderly, a vulnerable population with low reserve capacity, and even fewer have looked at changes in the rate of lung function decline.

OBJECTIVES

We evaluated the effect of long-term exposure to black carbon on levels and rates of decline in lung function in the elderly.

METHODS

FVC and FEV1 were measured one to six times during the period 1995-2011 in 858 men participating in the Normative Aging Study. Exposure to black carbon, a tracer of traffic emissions, was estimated by a spatiotemporal land use regression model. We investigated the effects of moving averages of black carbon of 1-5 years before the lung function measurement using linear mixed models.

MEASUREMENTS AND MAIN RESULTS

A 0.5 μg/m(3) increase in long-term exposure to black carbon was associated with an additional rate of decline in FVC and FEV1 of between 0.5% and 0.9% per year, respectively, depending on the averaging time. In addition, black carbon exposure before the baseline visit was associated with lower levels of both FVC and FEV1, with effect estimates increasing up to 6-7% with a 5-year average exposure.

CONCLUSIONS

Our results support adverse effects of long-term exposure to traffic particles on lung function level and rate of decline in the elderly and suggest that functionally significant differences in health and risk of disability occur below the annual Environmental Protection Agency National Air Quality Standards.

Highway proximity and black carbon from cookstoves as a risk factor for higher blood pressure in rural China

Air pollution in China and other parts of Asia poses large health risks and is an important contributor to global climate change. Almost half of Chinese homes use biomass and coal fuels for cooking and heating. China's economic growth and infrastructure development has led to increased emissions from coal-fired power plants and an expanding fleet of motor vehicles. Black carbon (BC) from incomplete biomass and fossil fuel combustion is the most strongly light-absorbing component of particulate matter (PM) air pollution and the second most important climate-forcing human emission. PM composition and sources may also be related to its human health impact. We enrolled 280 women living in a rural area of northwestern Yunnan where biomass fuels are commonly used. We measured their blood pressure, distance from major traffic routes, and daily exposure to BC (pyrolytic biomass combustion), water-soluble organic aerosol (organic aerosol from biomass combustion), and, in a subset, hopane markers (motor vehicle emissions) in winter and summer. BC had the strongest association with systolic blood pressure (SBP) (4.3 mmHg; P < 0.001), followed by PM mass and water-soluble organic mass. The effect of BC on SBP was almost three times greater in women living near the highway [6.2 mmHg; 95% confidence interval (CI), 3.6 to 8.9 vs. 2.6 mmHg; 95% CI, 0.1 to 5.2]. Our findings suggest that BC from combustion emissions is more strongly associated with blood pressure than PM mass, and that BC's health effects may be larger among women living near a highway and with greater exposure to motor vehicle emissions.

Ambient particulate air pollution and microRNAs in elderly men

BACKGROUND

Ambient particulate matter (PM) has been associated with mortality and morbidity for cardiovascular disease. MicroRNAs control gene expression at a posttranscriptional level. Altered microRNA expression has been reported in processes related to cardiovascular disease and PM exposure, such as systemic inflammation, endothelial dysfunction, and atherosclerosis. Polymorphisms in microRNA-related genes could influence response to PM.

METHODS

We investigated the association of exposure to ambient particles in several time windows (4-hour to 28-day moving averages) and blood leukocyte expression changes in 14 candidate microRNAs in 153 elderly males from the Normative Aging Study (examined 2005-2009). Potential effect modification by six single nucleotide polymorphisms (SNPs) in three microRNA-related genes was investigated. Fine PM (PM2.5), black carbon, organic carbon, and sulfates were measured at a stationary ambient monitoring site. Linear regression models, adjusted for potential confounders, were used to assess effects of particles and SNP-by-pollutant interaction. An in silico pathway analysis was performed on target genes of microRNAs associated with the pollutants.

RESULTS

We found a negative association for pollutants in all moving averages and miR-1, -126, -135a, -146a, -155, -21, -222, and -9. The strongest associations were observed with the 7-day moving averages for PM2.5 and black carbon and with the 48-hour moving averages for organic carbon. The association with sulfates was stable across the moving averages. The in silico pathway analysis identified 18 pathways related to immune response shared by at least two microRNAs; in particular, the "high-mobility group protein B1/advanced glycosylation end product-specific receptor signaling pathway" was shared by miR-126, -146a, -155, -21, and -222. No important associations were observed for miR-125a-5p, -125b, -128, -147, -218, and -96. We found significant SNP-by-pollutant interactions for rs7813, rs910925, and rs1062923 in GEMIN4 and black carbon and PM2.5 for miR-1, -126, -146a, -222, and -9, and for rs1640299 in DGCR8 and SO4 for miR-1 and -135a.

CONCLUSIONS

Exposure to ambient particles could cause a downregulation of microRNAs involved in processes related to PM exposure. Polymorphisms in GEMIN4 and DGCR8 could modify these associations.

PM2.5-induced cardiovascular dysregulation in rats is associated with elemental carbon and temperature-resolved carbon subfractions

Background

We tested the hypothesis that cardiovascular responses to PM_2.5 exposure will be enhanced in hypertensive rats and linked to specific carbonaceous pollutants in an urban industrial setting.

Methods

Spontaneously hypertensive rats were exposed by inhalation to concentrated PM_2.5 in an industrial area of Dearborn, Michigan, for four consecutive summer days. Blood pressure (BP), heart rate (HR) and HR variability (HRV) metrics (SDNN, RMSSD) were assessed by radiotelemetry and compared to 1 h- and 8 h-averaged fluctuations in PM_2.5 composition, with a focus on elemental and organic carbon (EC and OC, respectively), and temperature-resolved subfractions (EC1-EC5, PC (pyrolized carbon), and OC1-OC4), as well as other major and minor PM components.

Results

Mean HR and BP were increased, while HRV was decreased over 4 days of exposure. Using 1 h averages, EC (1 μg/m³ increase) was associated with increased HR of 11-32 bpm (4-11% increase), 1.2-1.5 ms (22-27%) decreases in SDNN, 3-14 mmHg (1.5-8%) increases in systolic BP, and 5-12 mmHg (4-9%) increases in diastolic BP. By comparison, associations with OC were negligible. Using 8 h averages, EC subfractions were linked with increased heart rate (EC1: 13 bpm; EC2, EC3, PC: <5 bpm) and SDNN (EC1> > EC2 > EC3, EC4, PC), but with decreased RMSSD (EC2, EC5 > EC3, EC4). Minimal effects were associated with OC and OC1. Associations between carbon subfractions and BP were negligible. Associations with non-carbonaceous components and trace elements were generally non-significant or of negligible effect size.

Conclusions

These findings are the first to describe associations between acute cardiovascular responses and thermally resolved carbon subfractions. We report that cardiovascular responses to PM_2.5 carbonaceous materials appear to be driven by EC and its EC1 fraction.

Black carbon emissions in gasoline exhaust and a reduction alternative with a gasoline particulate filter

Black carbon (BC) mass and solid particle number emissions were obtained from two pairs of gasoline direct injection (GDI) vehicles and port fuel injection (PFI) vehicles over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) drive cycles on gasoline and 10% by volume blended ethanol (E10). BC solid particles were emitted mostly during cold-start from all GDI and PFI vehicles. The reduction in ambient temperature had significant impacts on BC mass and solid particle number emissions, but larger impacts were observed on the PFI vehicles than the GDI vehicles. Over the FTP-75 phase 1 (cold-start) drive cycle, the BC mass emissions from the two GDI vehicles at 0 °F (-18 °C) varied from 57 to 143 mg/mi, which was higher than the emissions at 72 °F (22 °C; 12-29 mg/mi) by a factor of 5. For the two PFI vehicles, the BC mass emissions over the FTP-75 phase 1 drive cycle at 0 °F varied from 111 to 162 mg/mi, higher by a factor of 44-72 when compared to the BC emissions of 2-4 mg/mi at 72 °F. The use of a gasoline particulate filter (GPF) reduced BC emissions from the selected GDI vehicle by 73-88% at various ambient temperatures over the FTP-75 phase 1 drive cycle. The ambient temperature had less of an impact on particle emissions for a warmed-up engine. Over the US06 drive cycle, the GPF reduced BC mass emissions from the GDI vehicle by 59-80% at various temperatures. E10 had limited impact on BC emissions from the selected GDI and PFI vehicles during hot-starts. E10 was found to reduce BC emissions from the GDI vehicle by 15% at standard temperature and by 75% at 19 °F (-7 °C).

The effects of environmental chemical carcinogens on the microRNA machinery

The first evidence that microRNA expression is early altered by exposure to environmental chemical carcinogens in still healthy organisms was obtained for cigarette smoke. To date, the cumulative experimental data indicate that similar effects are caused by a variety of environmental carcinogens, including polycyclic aromatic hydrocarbons, nitropyrenes, endocrine disruptors, airborne mixtures, carcinogens in food and water, and carcinogenic drugs. Accordingly, the alteration of miRNA expression is a general mechanism that plays an important pathogenic role in linking exposure to environmental toxic agents with their pathological consequences, mainly including cancer development. This review summarizes the existing experimental evidence concerning the effects of chemical carcinogens on the microRNA machinery. For each carcinogen, the specific microRNA alteration signature, as detected in experimental studies, is reported. These data are useful for applying microRNA alterations as early biomarkers of biological effects in healthy organisms exposed to environmental carcinogens. However, microRNA alteration results in carcinogenesis only if accompanied by other molecular damages. As an example, microRNAs altered by chemical carcinogens often inhibits the expression of mutated oncogenes. The long-term exposure to chemical carcinogens causes irreversible suppression of microRNA expression thus allowing the transduction into proteins of mutated oncogenes. This review also analyzes the existing knowledge regarding the mechanisms by which environmental carcinogens alter microRNA expression. The underlying molecular mechanism involves p53-microRNA interconnection, microRNA adduct formation, and alterations of Dicer function. On the whole, reported findings provide evidence that microRNA analysis is a molecular toxicology tool that can elucidate the pathogenic mechanisms activated by environmental carcinogens.

Personal black carbon exposure influences ambulatory blood pressure: air pollution and cardiometabolic disease (AIRCMD-China) study

Few prospective studies have assessed the blood pressure effect of extremely high air pollution encountered in Asia's megacities. The objective of this study was to evaluate the association between combustion-related air pollution with ambulatory blood pressure and autonomic function. During February to July 2012, personal black carbon was determined for 5 consecutive days using microaethalometers in patients with metabolic syndrome in Beijing, China. Simultaneous ambient fine particulate matter concentration was obtained from the Beijing Municipal Environmental Monitoring Center and the US Embassy. Twenty-four-hour ambulatory blood pressure and heart rate variability were measured from day 4. Arterial stiffness and endothelial function were obtained at the end of day 5. For statistical analysis, we used generalized additive mixed models for repeated outcomes and generalized linear models for single/summary outcomes. Mean (SD) of personal black carbon and fine particulate matter during 24 hours was 4.66 (2.89) and 64.2 (36.9) μg/m(3). Exposure to high levels of black carbon in the preceding hours was associated significantly with adverse cardiovascular responses. A unit increase in personal black carbon during the previous 10 hours was associated with an increase in systolic blood pressure of 0.53 mm Hg and diastolic blood pressure of 0.37 mm Hg (95% confidence interval, 0.17-0.89 and 0.10-0.65 mm Hg, respectively), a percentage change in low frequency to high frequency ratio of 5.11 and mean interbeat interval of -0.06 (95% confidence interval, 0.62-9.60 and -0.11 to -0.01, respectively). These findings highlight the public health effect of air pollution and the importance of reducing air pollution.

Soot particles at an elevated site in eastern China during the passage of a strong cyclone

Atmospheric particles larger than 0.2 μm were collected at the top of Mt. Tai (36.25°N, 117.10°E, 1534 m a.s.l.) in eastern China in May 2008 during the passage of a strong cyclone. The particles were analyzed with electron microscopes and characterized by morphology, equivalent diameter and elemental composition. Soot particles with coating (coated soot particles) and those without apparent coating (naked soot particles) were predominant in the diameter range smaller than 0.6 μm in all samples. The number-size distribution of the relative abundance of naked soot particles in the prefrontal air was similar to that in the postfrontal air and their size modes were around 0.2-0.3 μm. However, the distribution of inclusions of coated soot particles showed a mode in the range of 0.1-0.3 μm. The coating degree of coated soot particles, which was defined by the ratio of the diameter of inclusion to the diameter of particle body, showed a mode around 0.5 with the range of 0.3-0.6. These results indicate that the status of soot particles in the prefrontal and postfrontal air was similar although air pollution levels were dramatically different. In addition, the relative abundance of accumulation mode particles increased with the decrease of soot particles after the front passage.

Environmental epigenetics: prospects for studying epigenetic mediation of exposure-response relationships

Changes in epigenetic marks such as DNA methylation and histone acetylation are associated with a broad range of disease traits, including cancer, asthma, metabolic disorders, and various reproductive conditions. It seems plausible that changes in epigenetic state may be induced by environmental exposures such as malnutrition, tobacco smoke, air pollutants, metals, organic chemicals, other sources of oxidative stress, and the microbiome, particularly if the exposure occurs during key periods of development. Thus, epigenetic changes could represent an important pathway by which environmental factors influence disease risks, both within individuals and across generations. We discuss some of the challenges in studying epigenetic mediation of pathogenesis and describe some unique opportunities for exploring these phenomena.

MiRNAs as regulators of the response to inhaled environmental toxins and airway carcinogenesis

miRNAs are a class of small, noncoding RNAs averaging 22 nucleotides in length that down-regulate gene expression by complimentary binding to the 3' UTR of target genes. A growing body of research suggests that these small RNA species play significant roles in modulating the cellular response to a variety of types of stress. In this review, we summarize the available literature regarding the general response of miRNA to cellular stress, and then specifically focus on the miRNA response to inhaled toxins. These miRNA responses to inhaled toxins appear to be recapitulated in lung carcinogenesis, opening the possibility that modulation of the miRNA response could be a novel strategy for chemoprevention.

Epigenomics in environmental health

This review considers the emerging relationships between environmental factors and epigenetic alterations and the application of genome-wide assessments to better define these relationships. First we will briefly cover epigenetic programming in development, one-carbon metabolism, and exposures that may disrupt normal developmental programming of epigenetic states. In addition, because a large portion of epigenetic research has focused on cancer, we discuss exposures associated with carcinogenesis including asbestos, alcohol, radiation, arsenic, and air pollution. Research on other exposures that may affect epigenetic states such as endocrine disruptors is also described, and we also review the evidence for epigenetic alterations associated with aging that may reflect cumulative effects of exposures. From this evidence, we posit potential mechanisms by which exposures modify epigenetic states, noting that understanding the true effect of environmental exposures on the human epigenome will require additional research with appropriate epidemiologic studies and application of novel technologies. With a more comprehensive understanding of the affects of exposures on the epigenome, including consideration of genetic background, the prediction of the toxic potential of new compounds may be more readily achieved, and may lead to the development of more personalized disease prevention and treatment strategies.

Exploring potential sources of differential vulnerability and susceptibility in risk from environmental hazards to expand the scope of risk assessment

Genetic factors, other exposures, individual disease states and allostatic load, psychosocial stress, and socioeconomic position all have the potential to modify the response to environmental exposures. Moreover, many of these modifiers covary with the exposure, leading to much higher risks in some subgroups. These are not theoretical concerns; rather, all these patterns have already been demonstrated in studies of the effects of lead and air pollution. However, recent regulatory impact assessments for these exposures have generally not incorporated these findings. Therefore, differential risk and vulnerability is a critically important but neglected area within risk assessment, and should be incorporated in the future.

Ambient pollutants, polymorphisms associated with microRNA processing and adhesion molecules: the Normative Aging Study

BACKGROUND

Particulate air pollution has been associated with cardiovascular morbidity and mortality, but it remains unclear which time windows and pollutant sources are most critical. MicroRNA (miRNA) is thought to be involved in cardiovascular regulation. However, little is known about whether polymorphisms in genes that process microRNAs influence response to pollutant exposure. We hypothesized that averaging times longer than routinely measured one or two day moving averages are associated with higher soluble intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) levels, and that stationary and mobile sources contribute differently to these effects. We also investigated whether single nucleotide polymorphisms (SNPs) in miRNA-processing genes modify these associations.

METHODS

sICAM-1 and sVCAM-1 were measured from 1999-2008 and matched to air pollution monitoring for fine particulate matter (PM2.5) black carbon, and sulfates (SO42-). We selected 17 SNPs in five miRNA-processing genes. Mixed-effects models were used to assess effects of pollutants, SNPs, and interactions under recessive inheritance models using repeated measures.

RESULTS

723 participants with 1652 observations and 1-5 visits were included in our analyses for black carbon and PM2.5. Sulfate data was available for 672 participants with 1390 observations. An interquartile range change in seven day moving average of PM2.5 (4.27 μg/m3) was associated with 3.1% (95%CI: 1.6, 4.6) and 2.5% (95%CI: 0.6, 4.5) higher sICAM-1 and sVCAM-1. Interquartile range changes in sulfates (1.39 μg/m3) were associated with 1.4% higher (95%CI: 0.04, 2.7) and 1.6% (95%CI: -0.4, 3.7) higher sICAM-1 and sVCAM-1 respectively. No significant associations were observed for black carbon. In interaction models with PM2.5, both sICAM-1 and sVCAM-1 levels were lower in rs1062923 homozygous carriers. These interactions remained significant after multiple comparisons adjustment.

CONCLUSIONS

PM2.5 seven day moving averages are associated with higher sICAM-1 and sVCAM-1 levels. SO4-2 seven day moving averages are associated with higher sICAM-1 and a suggestive association was observed with sVCAM-1 in aging men. SNPs in miRNA-processing genes may modify associations between ambient pollution and sICAM-1 and sVCAM-1, which are correlates of atherosclerosis and cardiovascular disease.

Preferential regulation of miRNA targets by environmental chemicals in the human genome

Background

microRNAs (miRNAs) represent a class of small (typically 22 nucleotides in length) non-coding RNAs that can degrade their target mRNAs or block their translation. Recent disease research showed the exposure to some environmental chemicals (ECs) can regulate the expression patterns of miRNAs, which raises the intriguing question of how miRNAs and their targets cope with the exposure to ECs throughout the genome.

Results

In this study, we comprehensively analyzed the properties of genes regulated by ECs (EC-genes) and found miRNA targets were significantly enriched among the EC-genes. Compared with the non-miRNA-targets, miRNA targets were roughly twice as likely to be EC-genes. By investigating the collection methods and other properties of the EC-genes, we demonstrated that the enrichment of miRNA targets was not attributed to either the potential collection bias of EC-genes, the presence of paralogs, longer 3'UTRs or more conserved 3'UTRs. Finally, we identified 1,842 significant concurrent interactions between 407 miRNAs and 497 ECs. This association network of miRNAs-ECs was highly modular and could be separated into 14 interconnected modules. In each module, miRNAs and ECs were closely connected, providing a good method to design accurate miRNA markers for ECs in toxicology research.

Conclusions

Our analyses indicated that miRNAs and their targets played important roles in cellular responses to ECs. Association analyses of miRNAs and ECs will help to broaden the understanding of the pathogenesis of such chemical components.

Gene-air pollution interaction and cardiovascular disease: a review

Genetic susceptibility is likely to play a role in response to air pollution. Hence, gene-environment interaction studies can be a tool for exploring the mechanisms and the importance of the pathway in the association between air pollution and a cardiovascular outcome. In this article, we present a systematic review of the studies that have examined gene-environment interactions in relation to the cardiovascular health effects of air pollutants. We identified 16 articles meeting our search criteria. Of these studies, most have focused on individual functional polymorphisms or individual candidate genes. Moreover, they were all based on 3 study populations that have been extensively investigated in relation to air pollution effects: the Normative Aging Study, Air Pollution and Inflammatory Response in Myocardial Infarction Survivors: Gene-Environment Interaction in a High Risk Group, and Multiethnic Study of Atherosclerosis. In conclusions, the studies differed substantially in both the cardiovascular outcomes examined and the polymorphisms examined, so there is little confirmation of results across cohorts. Gene-environment interaction studies can help explore the mechanisms and the potential pathway in the association between air pollution and a cardiovascular outcome; replication of findings and studies involving multiple cohorts would be needed to draw stronger conclusions.

microRNAs: implications for air pollution research

The purpose of this review is to provide an update of the current understanding on the role of microRNAs in mediating genetic responses to air pollutants and to contemplate on how these responses ultimately control susceptibility to ambient air pollution. Morbidity and mortality attributable to air pollution continues to be a growing public health concern worldwide. Despite several studies on the health effects of ambient air pollution, underlying molecular mechanisms of susceptibility and disease remain elusive. In the last several years, special attention has been given to the role of epigenetics in mediating, not only genetic and physiological responses to certain environmental insults, but also in regulating underlying susceptibility to environmental stressors. Epigenetic mechanisms control the expression of gene products, both basally and as a response to a perturbation, without affecting the sequence of DNA itself. These mechanisms include structural regulation of the chromatin structure, such as DNA methylation and histone modifications, and post-transcriptional gene regulation, such as microRNA mediated repression of gene expression. microRNAs are small noncoding RNAs that have been quickly established as key regulators of gene expression. As such, miRNAs have been found to control several cellular processes including apoptosis, proliferation and differentiation. More recently, research has emerged suggesting that changes in the expression of some miRNAs may be critical for mediating biological, and ultimately physiological, responses to air pollutants. Although the study of microRNAs, and epigenetics as a whole, has come quite far in the field of cancer, the understanding of how these mechanisms regulate gene-environment interactions to environmental exposures in everyday life is unclear. This article does not necessarily reflect the views and policies of the US EPA.

Epigenetic epidemiology of common complex disease: prospects for prediction, prevention, and treatment

As part of the PLoS Epigenetics Collection, Caroline Relton and George Davey Smith discuss the potential of epigenetics for the treatment and prevention of common complex diseases, including cancer.