Personal exposures to traffic-related air pollution and acute respiratory health among Bronx schoolchildren with asthma

Susceptibility of young and adult rats to the oral toxicity of titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) have potential applications as food additives, but concerns persist about their safety. Children are identified as having the highest exposure and may face the greatest health risks. However, the toxicological sensitivity of TiO2 NPs in different ages is not clear. Here, a comparative toxicity study of TiO2 NPs in 3-week (youth) and 8-week (adult) old Sprague-Dawley rats is reported following oral exposure at doses of 0, 10, 50, 200 mg kg(-1) body weight per day for 30 days. The organ mass and histology, blood biochemistry and redox state, intestinal function, and biodistribution of NPs are characterized. The results show that TiO2 NPs induce different toxic effects on young and adult rats. The liver edema, heart injuries and non-allergic mast cell activation in stomach tissues are found in young rats. On the other hand, only slight injury in the liver and kidney and decreased intestinal permeability and molybdenum contents are found in adult rats. Furthermore, TiO2 NP exposure can provoke reductive stress (i.e., increased reduced glutathione (GSH)/oxidized glutathione (GSSG) ratios) in plasmas through enhancing the glucose and GSH levels in young rats or reducing the glutathione peroxidase (GSH-Px) acitivity and GSSG levels in adult rats. These results suggest that different ages may require different biomarkers for identifying and monitoring oral toxicity of nanoparticles.

Recent advances in the epidemiologic investigation of risk factors for asthma: a review of the 2011 literature

The present review aims to identify and summarize epidemiologic investigations published during 2011 on the environmental risk factors for asthma. Potentially eligible papers were identified by a MEDLINE search. In total, 1,130 items were retrieved. Based on a broad definition of environment, the following topics were included: obesity, diet, vitamin D, air pollution, farming environment, and social factors. Some of the more relevant contributions included evidence that 1) obesity precedes asthma, 2) fruit consumption is longitudinally associated with a lower risk of asthma and atopy, 3) a comprehensive statewide smoking ban was followed by a reduction in hospital admissions for asthma, 4) asthma is one of the diseases showing the largest burdens due to environmental tobacco smoke, 5) traffic-related urban air pollution is associated with bronchial inflammation as measured by fractional exhaled nitric oxide and uncontrolled asthma, 6) aeroallergens and desert dust may contribute to the short-term effects of air pollution and asthma, and 7) maternal exposure to air pollution before and during pregnancy may alter the immune competence in offspring.

Associations between urban air pollution and pediatric asthma control in El Paso, Texas

Exposure to traffic-related pollutants poses a serious health threat to residents of major urban centers around the world. In El Paso, Texas, this problem is exacerbated by the region's arid weather, frequent temperature inversions, heavy border traffic, and an aged, poorly maintained vehicle fleet. The impact of exposure to traffic pollution, particularly on children with asthma, is poorly understood. Tracking the environmental health burden related to traffic pollution in El Paso is difficult, especially within school microenvironments, because of the lack of sensitive environmental health indicator data. The Asthma Control Questionnaire (ACQ) is a survey tool for the measurement of overall asthma control, yet has not previously been considered as an outcome in air pollution health effect research. We conducted a repeated measure panel study to examine weekly associations between ACQ scores and traffic- and non-traffic air pollutants among asthmatic schoolchildren in El Paso. In the main one- and two-pollutant epidemiologic models, we found non-significant, albeit suggestive, positive associations between ACQ scores and respirable particulate matter (PM10), coarse particulate matter (PM10-2.5), fine particulate matter (PM2.5), black carbon (BC), nitrogen dioxide (NO2), benzene, toluene, and ozone (O3). Notably, associations were stronger and significant for some subgroups, in particular among subjects taking daily inhaled corticosteroids. This pattern may indicate heightened immune system response in more severe asthmatics, those with worse asthma "control" and higher ACQ scores at baseline. If the ACQ is appropriately used in the context of air pollution studies, it could reflect clinically measurable and biologically relevant changes in lung function and asthma symptoms that result from poor air quality and may increase our understanding of how air pollution influences asthma exacerbation.

Traffic-related air pollutants and exhaled markers of airway inflammation and oxidative stress in New York City adolescents

Exposures to ambient diesel exhaust particles have been associated with respiratory symptoms and asthma exacerbations in children; however, epidemiologic evidence linking short-term exposure to ambient diesel exhaust particles with airway inflammation is limited. We conducted a panel study with asthmatic and nonasthmatic adolescents to characterize associations between ambient diesel exhaust particle exposures and exhaled biological markers of airway inflammation and oxidative stress. Over four weeks, exhaled breath condensate was collected twice a week from 18 asthmatics and 18 nonasthmatics (ages 14-19 years) attending two New York City schools and analyzed for pH and 8-isoprostane as indicators of airway inflammation and oxidative stress, respectively. Air concentrations of black carbon, a diesel exhaust particle indicator, were measured outside schools. Air measurements of nitrogen dioxide, ozone, and fine particulate matter were obtained for the closest central monitoring sites. Relationships between ambient pollutants and exhaled biomarkers were characterized using mixed effects models. Among all subjects, increases in 1- to 5-day averages of black carbon were associated with decreases in exhaled breath condensate pH, indicating increased airway inflammation, and increases in 8-isoprostane, indicating increased oxidative stress. Increases in 1- to 5-day averages of nitrogen dioxide were associated with increases in 8-isoprostane. Ozone and fine particulate matter were inconsistently associated with exhaled biomarkers. Associations did not differ between asthmatics and nonasthmatics. The findings indicate that short-term exposure to traffic-related air pollutants may increase airway inflammation and/or oxidative stress in urban youth and provide mechanistic support for associations documented between traffic-related pollutant exposures and respiratory morbidity.

Epidemiology of asthma in the United States

Incidence and prevalence rates of asthma can vary greatly according to population and location. The National Heart and Blood Institute of the National Institutes of Health defines asthma as a common chronic disorder of the airways that involves a complex interaction of airflow obstruction, bronchial hyperresponsiveness, and an underlying inflammation. This article uses the most common definitions and diagnostic methods for asthma. In 2009 there were 2.1 million asthma-related emergency department (ED) visits. ED visits lend an opportunity for providers to identify and intervene in the care of patients whose asthma is poorly controlled.

Integrated health impact assessment of travel behaviour: model exploration and application to a fuel price increase

Transportation policy measures often aim to change travel behaviour towards more efficient transport. While these policy measures do not necessarily target health, these could have an indirect health effect. We evaluate the health impact of a policy resulting in an increase of car fuel prices by 20% on active travel, outdoor air pollution and risk of road traffic injury. An integrated modelling chain is proposed to evaluate the health impact of this policy measure. An activity-based transport model estimated movements of people, providing whereabouts and travelled kilometres. An emission- and dispersion model provided air quality levels (elemental carbon) and a road safety model provided the number of fatal and non-fatal traffic victims. We used kilometres travelled while walking or cycling to estimate the time in active travel. Differences in health effects between the current and fuel price scenario were expressed in Disability Adjusted Life Years (DALY). A 20% fuel price increase leads to an overall gain of 1650 (1010-2330) DALY. Prevented deaths lead to a total of 1450 (890-2040) Years Life Gained (YLG), with better air quality accounting for 530 (180-880) YLG, fewer road traffic injuries for 750 (590-910) YLG and active travel for 170 (120-250) YLG. Concerning morbidity, mostly road safety led to 200 (120-290) fewer Years Lived with Disability (YLD), while air quality improvement only had a minor effect on cardiovascular hospital admissions. Air quality improvement and increased active travel mainly had an impact at older age, while traffic safety mainly affected younger and middle-aged people. This modelling approach illustrates the feasibility of a comprehensive health impact assessment of changes in travel behaviour. Our results suggest that more is needed than a policy rising car fuel prices by 20% to achieve substantial health gains. While the activity-based model gives an answer on what the effect of a proposed policy is, the focus on health may make policy integration more tangible. The model can therefore add to identifying win-win situations for both transport and health.

Respirable antimony and other trace-elements inside and outside an elementary school in Flagstaff, AZ, USA

Because people spend almost 90% of their time indoors, ambient air monitors may severely underestimate actual exposure to atmospheric particulate matter (PM). Therefore, it becomes increasingly important to better understand the microenvironments where people are spending their time. For preadolescent children, the best estimates of exposure may be inside of their school. In this study, 11 size fractions of PM were collected inside and outside of an elementary school in Flagstaff, AZ, USA. In particles<1 μm (PM1), the total mass indoors was similar to the mass outdoors (indoor:outdoor, I:O, ratio=0.92 ± 0.16). In the PM1-10 fraction, however, the mass concentration inside the school was highly elevated relative to outside the school (I:O ratios=13 ± 3). Mass concentrations of 27 elements were analyzed by ICP-MS. For all metals except for antimony (Sb), the PM1 and PM1-10 I:O ratios are found to be similar to the overall PM mass (near 1 and 13, respectively). In addition, indoor and outdoor particle size distributions reveal a crustal character for every element except Cu, Zn, Pb, and Sb. Therefore, we hypothesize that most of the PM mass inside the school is a result of transport from outside the school followed by resuspension from floors and clothing. In the PM1 fraction, the indoor mass of Sb was 86 times greater than the outdoor mass and had an air concentration of 17 ngm(-3) - greater than many urban areas around the world. Cu:Sb ratios and size distribution functions suggest that the excess source of PM1 indoor Sb results from the suspension of embedded Sb (used as a flame retardant) in the carpeting. This is the first study to observe elevated submicron Sb in schools and further studies are required to determine if this is a widespread health risk.

Repeated exposure to polycyclic aromatic hydrocarbons and asthma: effect of seroatopy

BACKGROUND

Exposure to traffic-related air pollutants, including polycyclic aromatic hydrocarbons (PAHs), can induce asthma. However, the effects of early repeated PAH exposure over time on different asthma phenotypes have not been examined.

OBJECTIVE

To assess associations between repeated PAH exposure, measured from prenatal personal and residential indoor monitors in children's homes, and asthma in an inner-city cohort.

METHODS

Prenatal exposure was assessed by personal air monitoring during 48 hours and exposure at 5 to 6 years of age by 2-week residential monitoring in the Columbia Center for Children's Environmental Health cohort. PAH was dichotomized into pyrene (representative semivolatile PAH) and the sum of 8 nonvolatile PAHs. High exposure to each was defined as measures above the median at both repeated time points. Asthma and wheeze were determined by validated questionnaires at ages 5 to 6 years. Children with specific IgE levels greater than 0.35 IU/mL to any of 5 indoor allergens were considered seroatopic.

RESULTS

Among all 354 children, repeated high exposure to pyrene was associated with asthma (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.13-3.20). Among 242 nonatopic children, but not those sensitized to indoor allergens (n = 87) or with elevated total IgE levels (n = 171), high pyrene levels were associated positively with asthma (OR, 2.89; 95% CI, 1.77-5.69), asthma medication use (OR, 2.28; 95% CI, 1.13-4.59), and emergency department visits for asthma (OR, 2.43; 95% CI, 1.20-4.91). Associations between the levels of the 8 nonvolatile PAHs and asthma were not observed, even when stratifying by seroatopy.

CONCLUSION

Nonatopic children may be more susceptible to the respiratory consequences of early pyrene exposures.

Childhood exposure to fine particulate matter and black carbon and the development of new wheeze between ages 5 and 7 in an urban prospective cohort

BACKGROUND

While exposures to urban fine particulate matter (PM(2.5)) and soot-black carbon (soot-BC) have been associated with asthma exacerbations, there is limited evidence on whether these pollutants are associated with the new development of asthma or allergy among young inner city children. We hypothesized that childhood exposure to PM(2.5) and the soot-BC component would be associated with the report of new wheeze and development of seroatopy in an inner city birth cohort.

METHODS

As part of the research being conducted by the Columbia Center of Children's Environmental Health (CCCEH) birth cohort study in New York City, two-week integrated residential monitoring of PM(2.5), soot-BC (based on a multi-wavelength integrating sphere method), and modified absorption coefficient (Abs*; based on the smoke stain reflectometer) was conducted between October 2005 and May 2011 for 408 children at ages 5-6 years old. Residential monitoring was repeated 6 months later (n=262) to capture seasonal variability. New wheeze was identified through the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaires during up to 3 years of follow-up and compared to a reference group that reported never wheeze, remitted wheeze, or persistent wheeze. Specific immunoglobulin (Ig) E against cockroach, mouse, cat, and dust mite and total IgE levels was measured in sera at ages 5 and 7 years.

RESULTS

PM(2.5), soot-BC, and Abs* measured at the first visit were correlated moderately with those at the second visit (Pearson r>0.44). Using logistic regression models, a positive association between PM(2.5) and new wheeze was found with adjusted odds ratio [95% confidence intervals] of 1.51 [1.05-2.16] per interquartile range (IQR). Positive but non-significant association was found between the development of new wheeze and soot-BC and (OR 1.40 [0.96-2.05]), and Abs* (OR 1.57 [0.91-2.68]); Significantly positive associations were found between air pollutant measurements and new wheeze when restricting to those participants with repeat home indoor measurements 6 months apart. Associations between pollutants and IgE levels were not detected.

CONCLUSIONS

Our findings suggest that childhood exposure to indoor air pollution, much of which penetrated readily from outdoor sources, may contribute to the development of wheeze symptoms among children ages 5 to 7 years.

Surfactant protein D (SP-D) alters cellular uptake of particles and nanoparticles

Surfactant protein D (SP-D) is primarily expressed in the lungs and modulates pro- and anti-inflammatory processes to toxic challenge, maintaining lung homeostasis. We investigated the interaction between NPs and SP-D and subsequent uptake by cells involved in lung immunity. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measured NP aggregation, particle size and charge in native human SP-D (NhSP-D) and recombinant fragment SP-D (rfhSP-D). SP-D aggregated NPs, especially following the addition of calcium. Immunohistochemical analysis of A549 epithelial cells investigated the co-localization of NPs and rfhSP-D. rfhSP-D enhanced the co-localisation of NPs to epithelial A549 cells in vitro. NP uptake by alveolar macrophages (AMs) and lung dendritic cells (LDCs) from C57BL/6 and SP-D knock-out mice were compared. AMs and LDCs showed decreased uptake of NPs in SP-D deficient mice compared to wild-type mice. These data confirmed an interaction between SP-D and NPs, and subsequent enhanced NP uptake.

Residential proximity to a major roadway is associated with features of asthma control in children

Background

While several studies suggest that traffic-related air pollutants are detrimental for respiratory health, few studies have examined relationships between residential proximity to a major roadway and asthma control in children. Furthermore, a major limitation of existing research is reliance on self-reported outcomes. We therefore determined the spatial relationship between the distance from a major roadway and clinical, physiologic and inflammatory features of asthma in a highly characterized sample of asthmatic children 6–17 years of age across a wide range of severities. We hypothesized that a closer residential proximity to a major roadway would be associated with increased respiratory symptoms, altered pulmonary function and a greater magnitude of airway and systemic inflammation.

Methodology/Principal Findings

224 children 6–17 years with confirmed asthma completed questionnaires and underwent spirometry, plethysmography, exhaled nitric oxide determination, exhaled breath condensate collection and venipuncture. Residential distance from a major roadway was determined by mapping the geographic coordinates of the residential address in Geographic Information System software. The distance between the home address and the nearest major roadway was calculated according to the shortest distance between the two points (i.e., “as the crow flies”). Asthmatic children living in closer proximity to a major roadway had an increased frequency of wheezing associated with increased medication requirements and more hospitalizations even after controlling for potential confounders. These children also had increased airway resistance, increased airway inflammation reflected by a lower breath condensate pH, and higher plasma EGF concentrations.

Conclusions/Significance

These findings suggest that closer residential proximity to a major roadway is associated with poorer asthma control in school-age children. Assessment of residential proximity to major roadways may be useful in the clinical evaluation of asthma in children.

Diesel exhaust particles and airway inflammation

PURPOSE OF REVIEW

Epidemiologic investigation has associated traffic-related air pollution with adverse human health outcomes. The capacity of diesel exhaust particles (DEPs), a major emission source air pollution particle, to initiate an airway inflammation has subsequently been investigated. We review the recent controlled human exposures to diesel exhaust and DEPs, and summarize the investigations into the associations between this emission source air pollution particle and airway inflammation.

RECENT FINDINGS

Using bronchoalveolar lavage, bronchial biopsies, and sputum collection, studies have demonstrated inflammation in the airways of healthy individuals after exposure to diesel exhaust and DEPs. This inflammation has included neutrophils, eosinophils, mast cells, and lymphocytes. Elevated expression and concentrations of inflammatory mediators have similarly been observed in the respiratory tract after diesel exhaust and DEP exposure. An increased sensitivity of asthmatic individuals to the proinflammatory effects of DEPs has not been confirmed.

SUMMARY

Inflammation after diesel exhaust and DEP exposure is evident at higher concentrations only; there appears to be a threshold dose for DEPs approximating 300 μg/m. The lack of a biological response to DEPs at lower concentrations may reflect a contribution of gaseous constituents or interactions between DEPs and gaseous air pollutants to the human inflammatory response and function loss.

A mixture of anatase and rutile TiO₂ nanoparticles induces histamine secretion in mast cells

Background

Histamine released from mast cells, through complex interactions involving the binding of IgE to FcεRI receptors and the subsequent intracellular Ca²⁺ signaling, can mediate many allergic/inflammatory responses. The possibility of titanium dioxide nanoparticles (TiO₂ NPs), a nanomaterial pervasively used in nanotechnology and pharmaceutical industries, to directly induce histamine secretion without prior allergen sensitization has remained uncertain.

Results

TiO₂ NP exposure increased both histamine secretion and cytosolic Ca²⁺ concentration ([Ca²⁺]_C) in a dose dependent manner in rat RBL-2H3 mast cells. The increase in intracellular Ca²⁺ levels resulted primarily from an extracellular Ca²⁺ influx via membrane L-type Ca²⁺ channels. Unspecific Ca²⁺ entry via TiO₂ NP-instigated membrane disruption was demonstrated with the intracellular leakage of a fluorescent calcein dye. Oxidative stress induced by TiO₂ NPs also contributed to cytosolic Ca²⁺ signaling. The PLC-IP₃-IP₃ receptor pathways and endoplasmic reticulum (ER) were responsible for the sustained elevation of [Ca²⁺]_C and histamine secretion.

Conclusion

Our data suggests that systemic circulation of NPs may prompt histamine release at different locales causing abnormal inflammatory diseases. This study provides a novel mechanistic link between environmental TiO₂ NP exposure and allergen-independent histamine release that can exacerbate manifestations of multiple allergic responses.

Modeling spatial variations of black carbon particles in an urban highway-building environment

Highway-building environments are prevalent in metropolitan areas. This paper presents our findings in investigating pollutant transport in a highway-building environment by combing field measurement and numerical simulations. We employ and improve the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model to simulate the spatial variations of black carbon (BC) concentrations near highway I-87 and an urban school in the South Bronx, New York. The results of CTAG simulations are evaluated against and agree adequately with the measurements of wind speed, wind directions, and BC concentrations. Our analysis suggests that the BC concentration at the measurement point of the urban school could decrease by 43-54% if roadside buildings were absent. Furthermore, we characterize two generalized conditions in a highway-building environment, i.e., highway-building canyon and highway viaduct-building. The former refers to the canyon between solid highway embankment and roadside buildings, where the spatial profiles of BC depend on the equivalent canyon aspect ratio and flow recirculation. The latter refers to the area between a highway viaduct (i.e., elevated highway with open space underneath) and roadside buildings, where strong flow recirculation is absent and the spatial profiles of BC are determined by the relative heights of the highway and buildings. The two configurations may occur at different locations or in the same location with different wind directions when highway geometry is complex. Our study demonstrates the importance of incorporating highway-building interaction into the assessment of human exposure to near-road air pollution. It also calls for active roles of building and highway designs in mitigating near-road exposure of urban population.