Cardiopulmonary responses of intratracheally instilled tire particles and constituent metal components

Potential Impacts of Energy and Vehicle Transformation Through 2050 on Oxidative Stress-Inducing PM2.5 Metals Concentration in Japan

The impacts of renewable energy shifting, passenger car electrification, and lightweighting through 2050 on the atmospheric concentrations of PM2.5 total mass and oxidative stress-inducing metals (PM2.5-Fe, Cu, and Zn) in Japan were evaluated using a regional meteorology-chemistry model. The surface concentrations of PM2.5 total mass, Fe, Cu, and Zn in the urban area decreased by 8%, 13%, 18%, and 5%, respectively. Battery electric vehicles (BEVs) have been considered to have no advantage in terms of non-exhaust PM emissions by previous studies. This is because the disadvantages (heavier weight increases tire wear, road wear, and resuspention) offset the advantages (regenerative braking system (RBS) reduces brake wear). However, the future lightweighting of drive battery and body frame were estimated to reduce all non-exhaust PM. Passenger car electrification only reduced PM2.5 concentration by 2%. However, Fe and Cu concentrations were more reduced (-8% and -13%, respectively) because they have high brake wear-derived and significantly reflects the benefits of BEV's RBS. The water-soluble fraction concentration of metals (induces oxidative stress in the body) was estimated based on aerosol acidity. The reduction of SOx, NOx, and NH3 emissions from on-road and thermal power plants slightly changed the aerosol acidity (pH ± 0.2). However, it had a negligible effect on water-soluble metal concentrations (maximum +2% for Fe and +0.5% for Cu and Zn). Therefore, the metal emissions reduction was more important than gaseous pollutants in decreasing the water-soluble metals that induces respiratory oxidative stress and passenger car electrification and lightweighting were effective means of achieving this.

Toxicity and health effects of ultrafine particles: Towards an understanding of the relative impacts of different transport modes

Exposure to particulate matter (PM) has been associated with a wide range of adverse health effects, but it is still unclear how particles from various transport modes differ in terms of toxicity and associations with different human health outcomes. This literature review aims to summarize toxicological and epidemiological studies of the effect of ultrafine particles (UFPs), also called nanoparticles (NPs, <100 nm), from different transport modes with a focus on vehicle exhaust (particularly comparing diesel and biodiesel) and non-exhaust as well as particles from shipping (harbor), aviation (airport) and rail (mainly subway/underground). The review includes both particles collected in laboratory tests and the field (intense traffic environments or collected close to harbor, airport, and in subway). In addition, epidemiological studies on UFPs are reviewed with special attention to studies aimed at distinguishing the effects of different transport modes. Results from toxicological studies indicate that both fossil and biodiesel NPs show toxic effects. Several in vivo studies show that inhalation of NPs collected in traffic environments not only impacts the lung, but also triggers cardiovascular effects as well as negative impacts on the brain, although few studies compared NPs from different sources. Few studies were found on aviation (airport) NPs, but the available results suggest similar toxic effects as traffic-related particles. There is still little data related to the toxic effects linked to several sources (shipping, road and tire wear, subway NPs), but in vitro results highlighted the role of metals in the toxicity of subway and brake wear particles. Finally, the epidemiological studies emphasized the current limited knowledge of the health impacts of source-specific UFPs related to different transport modes. This review discusses the necessity of future research for a better understanding of the relative potencies of NPs from different transport modes and their use in health risk assessment.

A Review of Road Traffic-Derived Non-Exhaust Particles: Emissions, Physicochemical Characteristics, Health Risks, and Mitigation Measures

Implementation of regulatory standards has reduced exhaust emissions of particulate matter from road traffic substantially in the developed world. However, nonexhaust particle emissions arising from the wear of brakes, tires, and the road surface, together with the resuspension of road dust, are unregulated and exceed exhaust emissions in many jurisdictions. While knowledge of the sources of nonexhaust particles is fairly good, source-specific measurements of airborne concentrations are few, and studies of the toxicology and epidemiology do not give a clear picture of the health risk posed. This paper reviews the current state of knowledge, with a strong focus on health-related research, highlighting areas where further research is an essential prerequisite for developing focused policy responses to nonexhaust particles.

Seasonal Variation, Chemical Composition, and PMF-Derived Sources Identification of Traffic-Related PM1, PM2.5, and PM2.5-10 in the Air Quality Management Region of Žilina, Slovakia

Particulate matter (PM) air pollution in the urban environment is mainly related to the presence of potential sources throughout the year. Road transport is one of the most important sources of PM in the urban environment, because it directly affects pedestrians. PM measurements were performed in the city of Žilina, Slovakia, at various road-traffic-related measurement stations over the course of several years. This paper evaluates changes in the concentration of the fine fraction (PM_2.5), the ultrafine fraction (PM₁), and the coarse fraction (PM_2.5–10) over time. PM concentrations were measured by reference gravimetric method. Significant changes in PM concentrations over time due to the diversification of pollution sources and other, secondary factors can be observed from the analysis of the measured data. PM samples were subjected to chemical analysis inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of elements (Mg, Al, Ca, Cr, Cu, Fe, Cd, Sb, Ba, Pb, Ni, and Zn). The seasonal variation of elements was evaluated, and the sources of PM_2.5, PM₁, and PM_2.5–10 were estimated using principal component analysis (PCA) and positive matrix factorization (PMF). PM_2.5 (maximum concentration of 148.95 µg/m³ over 24 h) and PM₁ (maximum concentration of 110.51 µg/m³ over 24 h) showed the highest concentrations during the heating season, together with the elements Cd, Pb, and Zn, which showed a significant presence in these fractions. On the other hand, PM_2.5–10 (maximum concentration of 38.17 µg/m³ over 24 h) was significantly related to the elements Cu, Sb, Ba, Ca, Cr, Fe, Mg, and Al. High correlation coefficients (r ≥ 0.8) were found for the elements Mg, Ca, Fe, Al, Cd, Pb, and Zn in the PM₁ fraction, Cd, Pb, and Zn in PM_2.5, and Ba, Sb, Fe, Cu, Cr, Mg, Al, and Ca in PM_2.5–10. Using PMF analysis, three major sources of PM (abrasion from tires and brakes, road dust resuspension/winter salting, and combustion processes) were identified for the PM_2.5 and PM₁ fractions, as well as for the coarse PM_2.5–10 fraction. This study reveals the importance of non-exhaust PM emissions in the urban environment.

Large global variations in measured airborne metal concentrations driven by anthropogenic sources

Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM_2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM_2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM_2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM_2.5 and PM₁₀ exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m⁻³). Kanpur, Hanoi, Beijing and Dhaka sites had annual mean arsenic concentrations that approached or exceeded the World Health Organization’s risk level for arsenic (6.6 ng m⁻³). The high concentrations of several potentially harmful metals in densely populated cites worldwide motivates expanded measurements and analyses.

Tyre and road wear particles (TRWP) - A review of generation, properties, emissions, human health risk, ecotoxicity, and fate in the environment

In this paper, the current knowledge on tyre and road wear particles (TRWP) is compiled regarding all environmental and health aspects. TRWP generated on roads during driving processes contribute to airborne non-exhaust emissions and are discussed in connection with the microplastic pollution. The major amount of TRWP consists of coarser heterogenous particles released to road surface, soils and aquatic compartments. The extensive compilation of annual emissions of tyre wear for numerous countries shows per-capita-masses ranging from 0.2 to 5.5 kg/(cap*a). Ecotoxicological studies revealed effects on aquatic organisms, but test concentrations and materials do not reflect environmental conditions. Contribution of tyre wear to PM10 accounts for up to approx. 11 mass %. A recent thorough risk assessment indicates the risk for human health via inhalation to be low, but no information is available on the risk caused by intake via the food chain. Data on degradation is scarce and most studies do not use realistic materials and conditions. The only published degradation study performed under environmental conditions implies a half-life of tyre rubber particles in soils of 16 months. For truck tyres, which mainly contain natural rubber, shorter periods were observed under optimum conditions in laboratory tests. Concentrations of tyre wear compiled from environmental monitoring studies show highly variable concentrations in road runoff, road dust, roadside soils, river sediments and river water, with a general decrease following the transport paths. However, the behaviour of TRWP in freshwater referring to transport, degradation, and sedimentation is still unclarified. Environmental monitoring of TRWP is still hampered by challenges for analytics. Thus, data on environmental concentrations is rare and has mainly exemplary character. Further research is needed with regard to emission factors, development of analytical methods for environmental matrices, long-period monitoring, fate in surface waters and soils, (eco)toxicological impacts and degradation under realistic conditions.

Characterization of metals in PM1 and PM10 and health risk evaluation at an urban site in the western Mediterranean

PM₁ and PM₁₀ samples collected in the urban center of Elche during two years were analyzed by Energy Dispersive X-Ray Fluorescence in order to determine the concentrations of the following metals: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Ba. The influence of traffic and Saharan dust intrusions on PM levels and metal content was studied in this work. The results indicate that the coarse fraction was affected more by variations in traffic intensity than the submicron fraction. The concentrations of Ca, commonly used as a tracer of road dust, showed the highest decreases during the weekends due to the reduction in traffic-induced resuspension. In contrast, Saharan events had a greater impact on the levels of other metals such as Ti and Fe, significantly affecting their seasonal variability. High concentrations of V and Ni compared with the values found at larger urban areas were observed. This could be attributed to a significant contribution from soils, Saharan dust and even ship emissions. Enrichment factors calculated using Ti as a reference element indicate that Zn and Cu are predominantly emitted by anthropogenic activities. In fact, Saharan dust intrusions had a minor influence on the average concentrations of these metals. Non-carcinogenic health hazards associated with exposure to airborne metals were lower than the safety threshold (hazard quotient < 1). Carcinogenic risks for Cr (VI) and Ni were between 10^-6 and 10^-4 and, therefore, within the range considered acceptable by the US EPA.

Chemical fractionation and mobility of traffic-related elements in road environments

Due to considerable progress in exhaust control emission technology and extensive regulatory work regarding this issue, non-exhaust sources of air pollution have become a growing concern. This research involved studying three types of road environment samples such as road dust, sludge from storm drains and roadside soil collected from heavily congested and polluted cities in Poland (Krakow, Warszawa, Opole and Wroclaw). Particles below 20 µm were examined since it was previously estimated that this fine fraction of road dust is polluted mostly by metals derived from non-exhaust sources of pollution such as brake linings wear. Chemical analysis of all samples was combined with a fractionation study using BCR protocol. It was concluded that the finest fractions of road environment samples were significantly contaminated with all of the investigated metals, in particular with Zn, Cu, both well-known key tracers of brake and tire wear. In Warszawa, the pollution index for Zn was on average 15-18 times the background value, in Krakow 12 times, in Wroclaw 8-12 times and in Opole 6-9 times the background value. The pollution index for Cu was on average 6-14 times the background in Warszawa, 7-8 times in Krakow, 4-6 times in Wroclaw and in Opole 5 times the background value. Fractionation study revealed that mobility of examined metals decreases in that order: Zn (43-62%) > Cd (25-42%) > Ni (6-16%) > Cu (3-14%) > Pb (1-8%). It should, however, be noted that metals even when not mobile in the environment can become a serious health concern when ingested or inhaled.

Wear and Tear of Tyres: A Stealthy Source of Microplastics in the Environment

Wear and tear from tyres significantly contributes to the flow of (micro-)plastics into the environment. This paper compiles the fragmented knowledge on tyre wear and tear characteristics, amounts of particles emitted, pathways in the environment, and the possible effects on humans. The estimated per capita emission ranges from 0.23 to 4.7 kg/year, with a global average of 0.81 kg/year. The emissions from car tyres (100%) are substantially higher than those of other sources of microplastics, e.g., airplane tyres (2%), artificial turf (12–50%), brake wear (8%) and road markings (5%). Emissions and pathways depend on local factors like road type or sewage systems. The relative contribution of tyre wear and tear to the total global amount of plastics ending up in our oceans is estimated to be 5–10%. In air, 3–7% of the particulate matter (PM_2.5) is estimated to consist of tyre wear and tear, indicating that it may contribute to the global health burden of air pollution which has been projected by the World Health Organization (WHO) at 3 million deaths in 2012. The wear and tear also enters our food chain, but further research is needed to assess human health risks. It is concluded here that tyre wear and tear is a stealthy source of microplastics in our environment, which can only be addressed effectively if awareness increases, knowledge gaps on quantities and effects are being closed, and creative technical solutions are being sought. This requires a global effort from all stakeholders; consumers, regulators, industry and researchers alike.

Effectiveness of traffic-related elements in tree bark and pollen abortion rates for assessing air pollution exposure on respiratory mortality rates

The majority of epidemiological studies correlate the cardiorespiratory effects of air pollution exposure by considering the concentrations of pollutants measured from conventional monitoring networks. The conventional air quality monitoring methods are expensive, and their data are insufficient for providing good spatial resolution. We hypothesized that bioassays using plants could effectively determine pollutant gradients, thus helping to assess the risks associated with air pollution exposure. The study regions were determined from different prevalent respiratory death distributions in the Sao Paulo municipality. Samples of tree flower buds were collected from twelve sites in four regional districts. The genotoxic effects caused by air pollution were tested through a pollen abortion bioassay. Elements derived from vehicular traffic that accumulated in tree barks were determined using energy-dispersive X-ray fluorescence spectrometry (EDXRF). Mortality data were collected from the mortality information program of Sao Paulo City. Principal component analysis (PCA) was applied to the concentrations of elements accumulated in tree barks. Pearson correlation and exponential regression were performed considering the elements, pollen abortion rates and mortality data. PCA identified five factors, of which four represented elements related to vehicular traffic. The elements Al, S, Fe, Mn, Cu, and Zn showed a strong correlation with mortality rates (R²>0.87) and pollen abortion rates (R²>0.82). These results demonstrate that tree barks and pollen abortion rates allow for correlations between vehicular traffic emissions and associated outcomes such as genotoxic effects and mortality data.

Early kidney damage induced by subchronic exposure to PM2.5 in rats

BACKGROUND

Particulate matter exposure is associated with respiratory and cardiovascular system dysfunction. Recently, we demonstrated that fine particles, also named PM_2.5, modify the expression of some components of the angiotensin and bradykinin systems, which are involved in lung, cardiac and renal regulation. The endocrine kidney function is associated with the regulation of angiotensin and bradykinin, and it can suffer damage even as a consequence of minor alterations of these systems. We hypothesized that exposure to PM_2.5 can contribute to early kidney damage as a consequence of an angiotensin/bradykinin system imbalance, oxidative stress and/or inflammation.

RESULTS

After acute and subchronic exposure to PM_2.5, lung damage was confirmed by increased bronchoalveolar lavage fluid (BALF) differential cell counts and a decrease of surfactant protein-A levels. We observed a statistically significant increment in median blood pressure, urine volume and water consumption after PM_2.5 exposure. Moreover, increases in the levels of early kidney damage markers were observed after subchronic PM_2.5 exposure: the most sensitive markers, β-2-microglobulin and cystatin-C, increased during the first, second, sixth and eighth weeks of exposure. In addition, a reduction in the levels of specific cytokines (IL-1β, IL-6, TNF-α, IL-4, IL-10, INF-γ, IL-17a, MIP-2 and RANTES), and up-regulated angiotensin and bradykinin system markers and indicators of a depleted antioxidant response, were also observed. All of these effects are in concurrence with the presence of renal histological lesions and an early pro-fibrotic state.

CONCLUSION

Subchronic exposure to PM_2.5 induced an early kidney damage response that involved the angiotensin/bradykinin systems as well as antioxidant and immune imbalance. Our study demonstrates that PM_2.5 can induce a systemic imbalance that not only affects the cardiovascular system, but also affects the kidney, which may also overall contribute to PM-related diseases.

Health effects of carbon-containing particulate matter: focus on sources and recent research program results

Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue.

Air pollution and public health: emerging hazards and improved understanding of risk

Despite past improvements in air quality, very large parts of the population in urban areas breathe air that does not meet European standards let alone the health-based World Health Organisation Air Quality Guidelines. Over the last 10 years, there has been a substantial increase in findings that particulate matter (PM) air pollution is not only exerting a greater impact on established health endpoints, but is also associated with a broader number of disease outcomes. Data strongly suggest that effects have no threshold within the studied range of ambient concentrations, can occur at levels close to PM2.5 background concentrations and that they follow a mostly linear concentration-response function. Having firmly established this significant public health problem, there has been an enormous effort to identify what it is in ambient PM that affects health and to understand the underlying biological basis of toxicity by identifying mechanistic pathways-information that in turn will inform policy makers how best to legislate for cleaner air. Another intervention in moving towards a healthier environment depends upon the achieving the right public attitude and behaviour by the use of optimal air pollution monitoring, forecasting and reporting that exploits increasingly sophisticated information systems. Improving air quality is a considerable but not an intractable challenge. Translating the correct scientific evidence into bold, realistic and effective policies undisputedly has the potential to reduce air pollution so that it no longer poses a damaging and costly toll on public health.

Particulate matter beyond mass: recent health evidence on the role of fractions, chemical constituents and sources of emission

Particulate matter (PM) is regulated in various parts of the world based on specific size cut offs, often expressed as 10 or 2.5 µm mass median aerodynamic diameter. This pollutant is deemed one of the most dangerous to health and moreover, problems persist with high ambient concentrations. Continuing pressure to re-evaluate ambient air quality standards stems from research that not only has identified effects at low levels of PM but which also has revealed that reductions in certain components, sources and size fractions may best protect public health. Considerable amount of published information have emerged from toxicological research in recent years. Accumulating evidence has identified additional air quality metrics (e.g. black carbon, secondary organic and inorganic aerosols) that may be valuable in evaluating the health risks of, for example, primary combustion particles from traffic emissions, which are not fully taken into account with PM2.5 mass. Most of the evidence accumulated so far is for an adverse effect on health of carbonaceous material from traffic. Traffic-generated dust, including road, brake and tire wear, also contribute to the adverse effects on health. Exposure durations from a few minutes up to a year have been linked with adverse effects. The new evidence collected supports the scientific conclusions of the World Health Organization Air Quality Guidelines and also provides scientific arguments for taking decisive actions to improve air quality and reduce the global burden of disease associated with air pollution.

Evaluation of potential for toxicity from subacute inhalation of tire and road wear particles in rats

Tire and road wear particles (TRWP) are a component of ambient particulate matter (PM) produced from the interaction of tires with the roadway. Inhalation of PM has been associated with cardiopulmonary morbidities and mortalities thought to stem from pulmonary inflammation. To determine whether TRWP may contribute to these events, the effects of subacute inhalation of TRWP were evaluated in rats. TRWP were collected at a road simulator laboratory, aerosolized, and used to expose male and female Sprague-Dawley rats (n = 10/treatment group) at ~10, 40, or 100 μg/m³ TRWP via nose-only inhalation for 6 h/day for 28 days. Particle size distribution of the aerosolized TRWP was found to be within the respirable range for rats. Toxicity was assessed following OECD guidelines (TG 412). No TRWP-related effects were observed on survival, clinical observations, body or organ weights, gross pathology, food consumption, immune system endpoints, serum chemistry, or biochemical markers of inflammation or cytotoxicity. Rare to few focal areas of subacute inflammatory cell infiltration associated with TWRP exposure were observed in the lungs of one mid and four high exposure animals, but not the low-exposure animals. These alterations were minimal, widely scattered and considered insufficient in extent or severity to have an impact on pulmonary function. Furthermore, it is expected that these focal lesions would remain limited and may undergo resolution without long-term or progressive pulmonary alterations. Therefore, from this study we identified a no-observable-adverse-effect-level (NOAEL) of 112 μg/m³ of TRWP in rats for future use in risk assessment of TRWP.

The policy relevance of wear emissions from road transport, now and in the future--an international workshop report and consensus statement

Road transport emissions are a major contributor to ambient particulate matter concentrations and have been associated with adverse health effects. Therefore, these emissions are targeted through increasingly stringent European emission standards. These policies succeed in reducing exhaust emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear and suspension in air of road dust. Is this a problem? To what extent do nonexhaust emissions contribute to ambient concentrations of PM10 or PM2.5? In the near future, wear emissions may dominate the remaining traffic-related PM10 emissions in Europe, mostly due to the steep decrease in PM exhaust emissions. This underlines the need to determine the relevance of the wear emissions as a contribution to the existing ambient PM concentrations, and the need to assess the health risks related to wear particles, which has not yet received much attention. During a workshop in 2011, available knowledge was reported and evaluated so as to draw conclusions on the relevance of traffic-related wear emissions for air quality policy development. On the basis of available evidence, which is briefly presented in this paper it was concluded that nonexhaust emissions and in particular suspension in air of road dust are major contributors to exceedances at street locations of the PM10 air quality standards in various European cities. Furthermore, wear-related PM emissions that contain high concentrations of metals may (despite their limited contribution to the mass of nonexhaust emissions) cause significant health risks for the population, especially those living near intensely trafficked locations. To quantify the existing health risks, targeted research is required on wear emissions, their dispersion in urban areas, population exposure, and its effects on health. Such information will be crucial for environmental policymakers as an input for discussions on the need to develop control strategies.

IMPLICATIONS

Road transport particulate matter (PM) emissions are associated with adverse health effects. Stringent policies succeed in reducing the exhaust PM emissions, but do not address "nonexhaust" emissions from brake wear, tire wear, road wear, and suspension in air of road dust. In the near future the nonexhaust emissions will dominate the road transport PM emissions. Based on the limited available evidence, it is argued that dedicated research is required on nonexhaust emissions and dispersion to urban areas from both an air quality and a public health perspective. The implicated message to regulators and policy makers is that road transport emissions continue to be an issue for health and air quality, despite the encouraging rapid decrease of tailpipe exhaust emissions.

Ultrafine particle characteristics in a rubber manufacturing factory

BACKGROUND

According to epidemiological research, exposure to rubber fumes can cause various types of cancer and can lead to an increase in death rate because of cardiovascular diseases.

OBJECTIVES

In this study, we have assessed the characteristics of ultrafine particles emitted into the air during the manufacturing of rubber products using waste tires.

METHODS

To assess the aerosol distribution of rubber fumes in the workplace from a product during curing, we have performed particle number concentration mapping using a handheld condensation particle counter. The particle number concentration of each process, count median diameter (CMD), and nanoparticle ratio (<100nm) were determined using an electrical low-pressure impactor (ELPI), and the surface area concentration was determined using a surface area monitor. The shape and composition of the sampled rubber fumes were analyzed using an ELPI-transmission electron microscopy grid method. Further, the rubber fume mass concentration was determined according to the Methods for the Determination of Hazardous Substances 47/2.

RESULTS

The results of particle mapping show that the rubber fumes were distributed throughout the air of the workplace. The concentration was the highest during the final process of the work. The particle number concentration and the surface area concentration were 545 000cm(-3) and 640 µm(2) cm(-3), respectively, approximately 10- and 4-fold higher than those in the outdoor background. During the final process, the CMD and the nanoparticle ratio were 26nm and 94%, respectively. Most of the rubber fume particles had a compact shape because of the coagulation between particles. The main components of these fumes were silicon and sulfur, and heavy metals such as zinc were detected in certain particles. The filter concentration of the rubber fumes was 0.22mg m(-3), lower than the UK workplace exposure limit of 0.6mg m(-3).

CONCLUSIONS

Therefore, the rubber manufacturing process is a potentially dangerous process that produces a high concentration of specific nanoparticles.

Spatial and seasonal distribution of aerosol chemical components in New York City: (2) road dust and other tracers of traffic-generated air pollution

We describe spatial and temporal patterns of seven chemical elements commonly observed in fine particulate matter (PM) and thought to be linked to roadway emissions that were measured at residential locations in New York City (NYC). These elements, that is, Si, Al, Ti, Fe, Ba, Br, and black carbon (BC), were found to have significant spatial and temporal variability at our 10 residential PM(2.5) sampling locations. We also describe pilot study data of near-roadway samples of both PM(10-2.5) and PM(2.5) chemical elements of roadway emissions. PM(2.5) element concentrations collected on the George Washington Bridge (GWB) connecting NYC and New Jersey were higher that similar elemental concentration measured at residential locations. Coarse-particle elements (within PM(10-2.5)) on the GWB were 10-100 times higher in concentration than their PM(2.5) counterparts. Roadway elements were well correlated with one another in both the PM(2.5) and PM(10-2.5) fractions, suggesting common sources. The same elements in the PM(2.5) collected at residential locations were less correlated, suggesting either different sources or different processing mechanisms for each element. Despite the fact that these elements are only a fraction of total PM(2.5) or PM(10-2.5) mass, the results have important implications for near-roadway exposures where elements with known causal links to health effects are shown to be at elevated concentrations in both the PM(2.5) and PM(10-2.5) size ranges.

Effects of atorvastatin on fine particle-induced inflammatory response, oxidative stress and endothelial function in human umbilical vein endothelial cells

The study is to explore the toxicity of organic extracts and water-soluble fraction of fine particles on human umbilical vein endothelial cells (HUVECs). The exposure doses were 100, 200 and 400 μg/ml, respectively, for two kinds of fractions. Moreover, atorvastatin was used for intervention study. HUVECs were stimulated by 400 μg/ml organic and water soluble extracts, respectively, immediately followed by treatment with atorvastatin in concentrations of 0.1 μmol/L, 1 μmol/L and 10 μmol/L, respectively. Cell viability, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), reactive oxygen species (ROS) and the expression of interleukin-6 beta (IL-6), tumor necrosis factor-α (TNF-α), endothelin-1 and P-selectin were determined in cells. The results showed that MDA and ROS increased in HUVECs after exposed to organic extracts and water-soluble fraction, whereas cell viability, NO and SOD decreased. The mRNA expression of IL-6, TNF-α, endothelin-1 (ET-1) and P-selectin increased after exposed to different fractions. Meanwhile, at the same exposure dose, water-soluble fraction caused more significant increase of MDA, IL-6, TNF-α and P-selectin and decrease of cell viability and NO when compared to organic extracts. Compared to no atorvastatin group, the levels of MDA, ROS and the expression of IL-6, TNF-α, ET-1 and P-selectin decreased in HUVECs in adding atorvastatin group, but cell viability, NO and SOD increased, which indicated that atorvastatin attenuated fine particle-induced inflammatory response, oxidative stress and endothelial damage. The results hinted that the inflammatory response, oxidative stress and endothelial dysfunction might be the mechanisms of cardiovascular injury induced by different fractions of ambient fine particles.

Redox and electrophilic properties of vapor- and particle-phase components of ambient aerosols

Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semi-volatile components may also contribute to many adverse health effects. The objectives of this study were: (i) assess for the first time the redox and electrophilic potential of vapor-phase components of ambient aerosols and (ii) evaluate the relative contributions of particle- and vapor-fractions to the hazard of a given aerosol. To achieve these objectives vapor- and particle-phase samples collected in Riverside (CA) were subjected to three chemical assays to determine their redox and electrophilic capacities. The results indicate that redox active components are mainly associated with the particle-phase, while electrophilic compounds are found primarily in the vapor-phase. Vapor-phase organic extracts were also capable of inducing the stress responding protein, heme-oxygenase-1 (HO-1), in RAW264.7 murine macrophages. These results demonstrate the importance of volatile components in the overall oxidative and electrophilic capacity of aerosols, and point out the need for inclusion of vapors in future health and risk assessment studies.

Zn and Cu isotopes as tracers of anthropogenic contamination in a sediment core from an urban lake

In this work, we use stable Zn and Cu isotopes to identify the sources and timing of the deposition of these metals in a sediment core from Lake Ballinger near Seattle, Washington, USA. The base of the Lake Ballinger core predates settlement in the region, while the upper sections record the effects of atmospheric emissions from a nearby smelter and rapid urbanization of the watershed. delta(66)Zn and delta(65)Cu varied by 0.50 per thousand and 0.29 per thousand, respectively, over the 500 year core record. Isotopic changes were correlated with the presmelter period ( approximately 1450 to 1900 with delta(66)Zn = +0.39 per thousand +/- 0.09 per thousand and delta(65)Cu = +0.77 per thousand +/- 0.06 per thousand), period of smelter operation (1900 to 1985 with delta(66)Zn = +0.14 +/- 0.06 per thousand and delta(65)Cu = +0.94 +/- 0.10 per thousand), and postsmelting/stable urban land use period (post 1985 with delta(66)Zn = 0.00 +/- 0.10 per thousand and delta(65)Cu = +0.82 per thousand +/- 0.12 per thousand). Rapid early urbanization during the post World War II era increased metal loading to the lake but did not significantly alter the delta(66)Zn and delta(65)Cu, suggesting that increased metal loads during this time were derived mainly from mobilization of historically contaminated soils. Urban sources of Cu and Zn were dominant since the smelter closed in the 1980s, and the delta(66)Zn measured in tire samples suggests tire wear is a likely source of Zn.

Differential pulmonary and cardiac effects of pulmonary exposure to a panel of particulate matter-associated metals

Biological mechanisms underlying the association between particulate matter (PM) exposure and increased cardiovascular health effects are under investigation. Water-soluble metals reaching systemic circulation following pulmonary exposure are likely exerting a direct effect. However, it is unclear whether specific PM-associated metals may be driving this. We hypothesized that exposure to equimolar amounts of five individual PM-associated metals would cause differential pulmonary and cardiac effects. We exposed male WKY rats (14 weeks old) via a single intratracheal instillation (IT) to saline or 1 micromol/kg body weight of zinc, nickel, vanadium, copper, or iron in sulfate form. Responses were analyzed 4, 24, 48, or 96 h after exposure. Pulmonary effects were assessed by bronchoalveolar lavage fluid levels of total cells, macrophages, neutrophils, protein, albumin, and activities of lactate dehydrogenase, gamma-glutamyl transferase, and n-acetyl glucosaminidase. Copper induced earlier pulmonary injury/inflammation, while zinc and nickel produced later effects. Vanadium or iron exposure induced minimal pulmonary injury/inflammation. Zinc, nickel, or copper increased serum cholesterol, red blood cells, and white blood cells at different time points. IT of nickel and copper increased expression of metallothionein-1 (MT-1) in the lung. Zinc, nickel, vanadium, and iron increased hepatic MT-1 expression. No significant changes in zinc transporter-1 (ZnT-1) expression were noted in the lung or liver; however, zinc increased cardiac ZnT-1 at 24 h, indicating a possible zinc-specific cardiac effect. Nickel exposure induced an increase in cardiac ferritin 96 h after IT. This data set demonstrating metal-specific cardiotoxicity is important in linking metal-enriched anthropogenic PM sources with adverse health effects.

Lung toxicity induced by intratracheal instillation of size-fractionated tire particles

Tire particles (TP) represent a significant component of urban air pollution (PM), constituting more than 10% of PM10 mass at urban locations with heavy traffic. The purpose of this study was to evaluate the effects of size-fractionated TP in an animal exposure model frequently used to assess the health effects of air pollutants. Potential pro-inflammatory and toxic effects of TP2.5 (<2.5 microm) and TP10 (<10 microm) were investigated through instillation of suspensions of these materials in BALB/c mice. Bronchoalveolar lavage fluid (BALF) was screened for total protein, lactate dehydrogenase (LDH), alkaline phosphatase (AP), and beta-glucuronidase (B-Gluc) as markers of cytotoxicity; glutathione (GSH) and superoxide dismutase (SOD) as markers of oxidative potential; and tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2 (MIP-2), and inflammatory cells as markers of inflammation. Concomitantly, histological analysis of TP-exposed lungs was performed. A single intratracheal instillation of 10 microg/100 microl, 100 microg/100 microl or 200 microg/100 microl was performed, and after 24h mice were euthanized and BALF examined. Inflammatory cellular profiles showed dose-dependent responses after TP10 exposure, while strong cytotoxic effects, including increases in total protein, LDH and AP, were observed to be associated to TP2.5 exposure. Histologically, TP10-treated lungs mainly showed inflammatory tissue infiltration, in contrast to TP2.5-treated lungs, where lysis of the alveolar barrier appeared to be the most characteristic lesion. Our biochemical, cytological, and histological results indicated differential lung toxicity mechanisms elicited by size-fractionated TP, in agreement with other studies performed in in vivo systems that have shown that lung responses to inhaled or instilled particles are affected by particle size. We conclude that lung toxicity induced by TP10 was primarily due to macrophage-mediated inflammatory events, while toxicity induced by TP2.5 appeared to be related more closely to cytotoxicity.

The effects of fine particle components on respiratory hospital admissions in children

BACKGROUND

Epidemiologic studies have demonstrated an association between acute exposure to ambient fine particles and both mortality and morbidity. Less is known about the relative impacts of the specific chemical constituents of particulate matter<2.5 microm in aerodynamic diameter (PM2.5) on hospital admissions.

OBJECTIVE

This study was designed to estimate the risks of exposure to PM2.5 and several species on hospital admissions for respiratory diseases among children.

DATA AND METHODS

We obtained data on daily counts of hospitalizations for children<19 and <5 years of age for total respiratory diseases and several subcategories including pneumonia, acute bronchitis, and asthma for six California counties from 2000 through 2003, as well as ambient concentrations of PM2.5 and its constituents, including elemental carbon (EC), organic carbon (OC), and nitrates (NO3). We used Poisson regression to estimate risks while controlling for important covariates.

RESULTS

We observed associations between several components of PM2.5 and hospitalization for all of the respiratory outcomes examined. For example, for total respiratory admissions for children<19 years of age, the interquartile range for a 3-day lag of PM2.5, EC, OC, NO3, and sulfates was associated with an excess risk of 4.1% [95% confidence interval (CI), 1.8-6.4], 5.4% (95% CI, 0.8-10.3), 3.4% (95% CI, 1.1-5.7), 3.3% (95% CI, 1.1-5.5), and 3.0% (95% CI, 0.4-5.7), respectively. We also observed associations for several metals. Additional associations with several of the species, including potassium, were observed in the cool season.

CONCLUSION

Components of PM2.5 were associated with hospitalization for several childhood respiratory diseases including pneumonia, bronchitis, and asthma. Because exposure to components (e.g., EC, OC, NO3, and K) and their related sources, including diesel and gasoline exhaust, wood smoke, and other combustion sources, are ubiquitous in the urban environment, it likely represents an identifiable and preventable risk factor for hospitalization for children.

Ambient particulates alter vascular function through induction of reactive oxygen and nitrogen species

Previous studies have shown a link between inhaled particulate matter (PM) exposure in urban areas and susceptibility to cardiovascular diseases. Although an oxidative stress pathway is strongly implicated, the locus of generation of reactive oxygen species (ROS) and the mechanisms by which these radicals exert their effects remain to be characterized. To test the hypothesis that exposure to environmentally relevant inhaled concentrated ambient PM (CAPs) enhances atherosclerosis through induction of vascular ROS and reactive nitrogen species. High-fat chow fed apolipoprotein E(-/-) mice were exposed to CAPs of less than 2.5 microm (PM(2.5)) or filtered air (FA), for 6 h/day, 5 days/week, for 4 months in Manhattan, NY. Atherosclerotic lesions were analyzed by histomorphometricly. Vascular reactivity, superoxide generation, mRNA expression of NADPH (nicotinamide adenine dinucleotide phosphate, reduced) oxidase subunits, inducible nitric oxide synthase, endothelial nitric oxide synthase, and GTP cyclohydrolase I were also assessed. Manhattan PM(2.5) CAPs were characterized by higher concentrations of organic and elemental carbon. Analysis of vascular responses revealed significantly decreased phenylephrine constriction in CAPs-exposed mice, which was restored by a soluble guanine cyclase inhibitor 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one. Vascular relaxation to A23187, but not to acetylcholine, was attenuated in CAPs mice. Aortic expression of NADPH oxidase subunits (p47(phox) and rac1) and iNOS were markedly increased, paralleled by increases in superoxide generation and extensive protein nitration in the aorta. The composite plaque area of thoracic aorta was significantly increased with pronounced macrophage infiltration and lipid deposition in the CAPs mice. CAPs exposure in Manhattan alters vasomotor tone and enhances atherosclerosis through NADPH oxidase dependent pathways.

Systemic translocation of (70)zinc: kinetics following intratracheal instillation in rats

Mechanisms of particulate matter (PM)-induced cardiotoxicity are not fully understood. Direct translocation of PM-associated metals, including zinc, may mediate this effect. We hypothesized that following a single intratracheal instillation (IT), zinc directly translocates outside of the lungs, reaching the heart. To test this, we used high resolution magnetic sector field inductively coupled plasma mass spectrometry to measure levels of five stable isotopes of zinc ((64)Zn, (66)Zn, (67)Zn, (68)Zn, (70)Zn), and copper in lungs, plasma, heart, liver, spleen, and kidney of male Wistar Kyoto rats (13 weeks old, 250-300 g), 1, 4, 24, and 48 h following a single IT or oral gavage of saline or 0.7 micromol/rat (70)Zn, using a solution enriched with 76.6% (70)Zn. Natural abundance of (70)Zn is 0.62%, making it an easily detectable tracer following exposure. In IT rats, lung (70)Zn was highest 1 h post IT and declined by 48 h. Liver endogenous zinc was increased 24 and 48 h post IT. (70)Zn was detected in all extrapulmonary organs, with levels higher following IT than following gavage. Heart (70)Zn was highest 48 h post IT. Liver, spleen and kidney (70)Zn peaked 4 h following gavage, and 24 h following IT. (70)Zn IT exposure elicited changes in copper homeostasis in all tissues. IT instilled (70)Zn translocates from lungs into systemic circulation. Route of exposure affects (70)Zn translocation kinetics. Our data suggests that following pulmonary exposure, zinc accumulation and subsequent changes in normal metal homeostasis in the heart and other organs could induce cardiovascular injury.

Subchronic inhalation of zinc sulfate induces cardiac changes in healthy rats

Zinc is a common metal in most ambient particulate matter (PM), and has been proposed to be a causative component in PM-induced adverse cardiovascular health effects. Zinc is also an essential metal and has the potential to induce many physiological and nonphysiological changes. Most toxicological studies employ high levels of zinc. We hypothesized that subchronic inhalation of environmentally relevant levels of zinc would cause cardiac changes in healthy rats. To address this, healthy male WKY rats (12 weeks age) were exposed via nose only inhalation to filtered air or 10, 30 or 100 microg/m(3) of aerosolized zinc sulfate (ZnSO(4)), 5 h/day, 3 days/week for 16 weeks. Necropsies occurred 48 h after the last exposure to ensure effects were due to chronic exposure rather than the last exposure. No significant changes were observed in neutrophil or macrophage count, total lavageable cells, or enzyme activity levels (lactate dehydrogenase, n-acetyl beta-D-glucosaminidase, gamma-glutamyl transferase) in bronchoalveolar lavage fluid, indicating minimal pulmonary effect. In the heart, cytosolic glutathione peroxidase activity decreased, while mitochondrial ferritin levels increased and succinate dehydrogenase activity decreased, suggesting a mitochondria-specific effect. Although no cardiac pathology was seen, cardiac gene array analysis indicated small changes in genes involved in cell signaling, a pattern concordant with known zinc effects. These data indicate that inhalation of zinc at environmentally relevant levels induces cardiac effects. While changes are small in healthy rats, these may be especially relevant in individuals with pre-existent cardiovascular disease.