Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution

Oxidative stress and calcium signaling in the adverse effects of environmental particles (PM10)

This review focuses on the potential role that oxidative stress plays in the adverse effects of PM(10). The central hypothesis is that the ability of PM(10) to cause oxidative stress underlies the association between increased exposure to PM(10) and both exacerbations of lung disease and lung cancer. Pulmonary inflammation may also underlie the cardiovascular effects seen following increased PM(10), although the mechanisms of the cardiovascular effects of PM(10) are not well understood. PM(10) is a complex mix of various particle types and several of the components of PM(10) are likely to be involved in the induction of oxidative stress. The most likely of these are transition metals, ultrafine particle surfaces, and organic compounds. In support of this hypothesis, oxidative stress arising from PM(10) has been shown to activate a number of redox-responsive signaling pathways in lung target cells. These pathways are involved in expression of genes that play a role in responses relevant to inflammation and pathological change, including MAPKs, NF-kappaB, AP-1, and histone acetylation. Oxidative stress from particles is also likely to play an important role in the carcinogenic effects associated with PM(10) and hydroxyl radicals from PM(10) cause DNA damage in vitro.

Airborne particles of the california central valley alter the lungs of healthy adult rats

Epidemiologic studies have shown that airborne particulate matter (PM) with a mass median aerodynamic diameter < 10 microm (PM10) is associated with an increase in respiratory-related disease. However, there is a growing consensus that particles < 2.5 microm (PM2.5), including many in the ultrafine (< 0.1 microm) size range, may elicit greater adverse effects. PM is a complex mixture of organic and inorganic compounds; however, those components or properties responsible for biologic effects on the respiratory system have yet to be determined. During the fall and winter of 2000-2001, healthy adult Sprague-Dawley rats were exposed in six separate experiments to filtered air or combined fine (PM2.5) and ultrafine portions of ambient PM in Fresno, California, enhanced approximately 20-fold above outdoor levels. The intent of these studies was to determine if concentrated fine/ultrafine fractions of PM are cytotoxic and/or proinflammatory in the lungs of healthy adult rats. Exposures were for 4 hr/day for 3 consecutive days. The mean mass concentration of particles ranged from 190 to 847 microg/m3. PM was enriched primarily with ammonium nitrate, organic and elemental carbon, and metals. Viability of cells recovered by bronchoalveolar lavage (BAL) from rats exposed to concentrated PM was significantly decreased during 4 of 6 weeks, compared with rats exposed to filtered air (p< 0.05). Total numbers of BAL cells were increased during 1 week, and neutrophil numbers were increased during 2 weeks. These observations strongly suggest exposure to enhanced concentrations of ambient fine/ultrafine particles in Fresno is associated with mild, but significant, cellular effects in the lungs of healthy adult rats.

The U.S. Environmental Protection Agency Particulate Matter Health Effects Research Centers Program: a midcourse report of status, progress, and plans

In 1998 Congress mandated expanded U.S. Environmental Protection Agency (U.S. EPA) health effects research on ambient air particulate matter (PM) and a National Research Council (NRC) committee to provide research oversight. The U.S. EPA currently supports intramural and extramural PM research, including five academically based PM centers. The PM centers in their first 2.5 years have initiated research directed at critical issues identified by the NRC committee, including collaborative activities, and sponsored scientific workshops in key research areas. Through these activities, there is a better understanding of PM health effects and scientific uncertainties. Future PM centers research will focus on long-term effects associated with chronic PM exposures. This report provides a synopsis of accomplishments to date, short-term goals (during the next 2.5 years) and longer-term goals. It consists of six sections: biological mechanisms, acute effects, chronic effects, dosimetry, exposure assessment, and the specific attributes of a coordinated PM centers program.

Chronic exposure to high levels of particulate air pollution and small airway remodeling

Recent evidence suggests that chronic exposure to high levels of ambient particulate matter (PM) is associated with decreased pulmonary function and the development of chronic airflow obstruction. To investigate the possible role of PM-induced abnormalities in the small airways in these functional changes, we examined histologic sections from the lungs of 20 women from Mexico City, a high PM locale. All subjects were lifelong residents of Mexico City, were never-smokers, never had occupational dust exposure, and never used biomass fuel for cooking. Twenty never-smoking, non-dust-exposed subjects from Vancouver, British Columbia, Canada, a low PM region, were used as a control. By light microscopy, abnormal small airways with fibrotic walls and excess muscle, many containing visible dust, were present in the Mexico City lungs. Formal grading analysis confirmed the presence of significantly greater amounts of fibrous tissue and muscle in the walls of the airways in the Mexico City compared with the Vancouver lungs. Electron microscopic particle burden measurements on four cases from Mexico City showed that carbonaceous aggregates of ultrafine particles, aggregates likely to be combustion products, were present in the airway mucosa. We conclude that PM penetrates into and is retained in the walls of small airways, and that, even in nonsmokers, long-term exposure to high levels of ambient particulate pollutants is associated with small airway remodeling. This process may produce chronic airflow obstruction.

Temporal variation of hydroxyl radical generation and 8-hydroxy-2'-deoxyguanosine formation by coarse and fine particulate matter

AIMS

To determine the induction of 8-hydroxy-2'-deoxyguanosine (8-OHdG) by fine (<2.5 microm) and coarse (10-2.5 microm) particulate matter (PM) sampled over time at one sampling location, and to relate the observed effects to the hydroxyl radical (*OH) generating activities and transition metal content of these samples, and to meteorological parameters.

METHODS

Weekly samples of coarse and fine PM were analysed for H(2)O(2) dependent *OH formation using electron spin resonance (ESR) and formation of 8-OHdG in calf thymus DNA using an immuno-dotblot assay. Immunocytochemistry was used to determine 8-OHdG formation in A549 human epithelial lung cells. To determine temporal effects, samples from six weeks in summer and six weeks in autumn/winter were compared using ESR and the dotblot assay. Concentrations of leachable V, Cr, Fe, Ni, and Cu were determined by inductively coupled plasma mass spectrometry.

RESULTS

Both PM fractions elicited *OH generation as well as 8-OHdG formation in calf thymus DNA and in A549 cells. 8-OHdG formation in the naked DNA was significantly related to *OH generation, but not to metal concentrations except for copper. A significantly higher *OH generation was observed for coarse PM, but not fine PM collected during the autumn/winter season; this was not due to differences in sampled mass or metal content. Specific weather conditions under which increased *OH formation in the coarse mode was observed suggest that other, as yet unknown, anthropogenic components might affect the radical generating capacity of PM.

CONCLUSIONS

Both coarse and fine PM are able to generate *OH, and induce formation of 8-OHdG. When considered at equal mass, *OH formation shows considerable variability with regard to the fraction of PM, as well as the sampling season. The toxicological implications of this heterogeneity in *OH formation by PM, as can be easily determined by ESR, need further investigation.

Lung cancer and related risk factors: an update of the literature

At the present time, lung cancer is the leading cause of cancer-related death in males. Diagnostic difficulty makes detection complicated and this, in conjunction with the low survival rate, renders the disease a serious health problem. In-depth knowledge of associated risk factors is therefore called for, in order to prevent or at least reduce the appearance of lung cancer and to open new avenues of research. Although the disease has a multicausal aetiology, tobacco accounts for 85-90% of all cases. This paper reviews the current situation, dividing the risk factors, for study purposes, into two groups; intrinsic (non-modifiable) and extrinsic (modifiable).

The public health benefits of insulation retrofits in existing housing in the United States

BACKGROUND

Methodological limitations make it difficult to quantify the public health benefits of energy efficiency programs. To address this issue, we developed a risk-based model to estimate the health benefits associated with marginal energy usage reductions and applied the model to a hypothetical case study of insulation retrofits in single-family homes in the United States.

METHODS

We modeled energy savings with a regression model that extrapolated findings from an energy simulation program. Reductions of fine particulate matter (PM2.5) emissions and particle precursors (SO2 and NOx) were quantified using fuel-specific emission factors and marginal electricity analyses. Estimates of population exposure per unit emissions, varying by location and source type, were extrapolated from past dispersion model runs. Concentration-response functions for morbidity and mortality from PM2.5 were derived from the epidemiological literature, and economic values were assigned to health outcomes based on willingness to pay studies.

RESULTS

In total, the insulation retrofits would save 800 TBTU (8 x 10(14) British Thermal Units) per year across 46 million homes, resulting in 3,100 fewer tons of PM2.5, 100,000 fewer tons of NOx, and 190,000 fewer tons of SO2 per year. These emission reductions are associated with outcomes including 240 fewer deaths, 6,500 fewer asthma attacks, and 110,000 fewer restricted activity days per year. At a state level, the health benefits per unit energy savings vary by an order of magnitude, illustrating that multiple factors (including population patterns and energy sources) influence health benefit estimates. The health benefits correspond to 1.3 billion dollars per year in externalities averted, compared with 5.9 billion dollars per year in economic savings.

CONCLUSION

In spite of significant uncertainties related to the interpretation of PM2.5 health effects and other dimensions of the model, our analysis demonstrates that a risk-based methodology is viable for national-level energy efficiency programs.

Biological activities of organic compounds adsorbed onto ambient air particles: comparison between the cities of Teplice and Prague during the summer and winter seasons 2000-2001

The capital of the Czech Republic, Prague, appears today to be one of the most polluted residential areas in the country, whereas air pollution in the Northern Bohemia region (the former "Black Triangle Region") has substantially decreased during the last decade, especially with respect to the gaseous pollutant SO(2). This study evaluated the biological activities of complex mixtures of organic compounds adsorbed onto ambient air particles (PM10) collected during the summer and winter seasons of 2000-2001 at three monitoring sites--Teplice (TP), Prague-Smíchov (PRG-SM) (city centre) and Prague-Libus (PRG-LB) (suburban area). The following short-term in vitro assays with strikingly different endpoints were used: a bacterial mutagenicity test using the Salmonella typhimurium tester strain TA98 and YG1041, an acellular assay (CT DNA) combined with 32P-postlabelling to evaluate DNA adduct-forming potency and the chick embryotoxicity screening test (CHEST). The results of the mutagenicity test with the YG1041 strain, the acellular genotoxicity (DNA adducts) and the embryotoxicity tests responded to the amount of eight carcinogenic polycyclic aromatic hydrocarbons (PAHs) analysed in the EOM (dichloromethane extractable organic matter) samples tested. Nevertheless, the biological effects of the EOM did not differ between locations. The highest biological activity of the ambient air in terms of organic compounds associated with particles (per unit volume of air) was seen in the Prague city centre during both summer and winter seasons. At this location, B[a]P concentration ranged from 0.1 to 8.9 ng/m(3) (mean 0.3 and 3.6 ng/m(3) for summer and winter seasons, respectively), 13 PAHs ranged from 11 to 343 ng/m(3) (mean 52 and 160 ng/m(3) for summer and winter seasons, respectively). Generally, using in vitro tests, higher ambient air activity was found in the winter season as compared with the summer season at all three monitoring sites (TA98 +S9, approximately 4-fold; YG1041 -S9, approximately 5-fold; YG1041 +S9, approximately 8-fold; CT DNA +S9, approximately 10-fold; CHEST, approximately 10-fold; B[a]P, carcinogenic PAHs and total PAHs analysed, more than 10-fold). The different proportions of individual PAHs found in the summer and winter samples suggested traffic as a major emission source in the summer and, additionally, residential heating in the winter season at all three monitoring sites. The DNA adduct patterns resulting from the in vitro acellular assay also demonstrated similar major emission sources at all three locations. The study shows that particle-bound carcinogenic-PAH concentrations may be taken as an index for the biologically active (mutagenic, genotoxic, embryotoxic) components in air particulate samples. Therefore, high-quality monitoring data of carcinogenic PAHs may be useful for epidemiological studies of the impact of air pollution on the health of the population and for helping decision makers to improve our environment.

Environmental polycyclic aromatic hydrocarbons, benzo(a) pyrene (BaP) and BaP-quinones, enhance IgE-mediated histamine release and IL-4 production in human basophils

Polycyclic aromatic hydrocarbons (PAHs) are major components of diesel exhaust particles found in pollutant respirable particles. There is growing evidence that these fossil fuel combustion products exacerbate allergic inflammation. Basophils contribute to allergic inflammation through the release of preformed and granule-derived mediators. To determine whether allergens and PAHs interact, we incubated human basophils with PAHs and measured the release of histamine and IL-4 with and without added antigen. None of the PAHs induced mediator release by itself and none affected total cellular histamine levels. However, several PAHs enhanced histamine release and IL-4 production in response to crosslinking the high-affinity IgE receptor, Fc epsilon RI. The enhancement seen with 1,6-BaP-quinone involved an increase in tyrosine phosphorylation in several different substrates, including the Fc epsilon RI-associated tyrosine kinase, Lyn, and elevated reactive oxygen species (ROS) levels detected by dichlorofluorescein fluorescence and flow cytometry. The PAH-induced enhancement of mediator release and ROS production could be inhibited with the antioxidant N-acetylcysteine. These data provide further evidence that environmental pollutants can influence allergic inflammation through enhanced Fc epsilon RI-coupled mediator release from human basophils.

Diesel exhaust particles in lung acutely enhance experimental peripheral thrombosis

BACKGROUND

Pollution by particulates has consistently been associated with increased cardiovascular morbidity and mortality, but a plausible biological basis for this association is lacking.

METHODS AND RESULTS

Diesel exhaust particles (DEPs) were instilled into the trachea of hamsters, and blood platelet activation, experimental thrombosis, and lung inflammation were studied. Doses of 5 to 500 micro g of DEPs per animal induced neutrophil influx into the bronchoalveolar lavage fluid with elevation of protein and histamine but without lactate dehydrogenase release. The same doses enhanced experimental arterial and venous platelet rich-thrombus formation in vivo. Blood samples taken from hamsters 30 and 60 minutes after instillation of 50 micro g of DEPs yielded accelerated aperture closure (ie, platelet activation) ex vivo, when analyzed in the Platelet Function Analyser (PFA-100). The direct addition of as little as 0.5 micro g/mL DEPs to untreated hamster blood significantly shortened closure time in vitro.

CONCLUSIONS

The intratracheal instillation of DEPs leads to lung inflammation as well as a rapid activation of circulating blood platelets. The kinetics of platelet activation are consistent with the reported clinical occurrence of thrombotic complications after exposure to pollutants. Our findings, therefore, provide a plausible explanation for the increase in cardiovascular morbidity and mortality accompanying urban air pollution.

Description and demonstration of the EXPOLIS simulation model: two examples of modeling population exposure to particulate matter

As a part of the EXPOLIS study, a stochastic exposure-modeling framework was developed. The framework is useful to compare exposure distributions of different (sub-) populations or different scenarios, and to gain insight into population exposure distributions and exposure determinants. It was implemented in an MS-Excel workbook using @Risk add-on software. Basic concept of the framework is that time-weighted average exposure is a sum of partial exposures in the visited microenvironments. Partial exposure is determined by the concentration and the time spent in the microenvironment. In the absence of data, indoor concentrations are derived as a function of ambient concentrations, effective penetration rates and contribution of indoor sources. Framework input parameters are described by probability distributions. A lognormal distribution is assumed for the microenvironment concentrations and for the contribution of indoor sources, and a beta distribution for the time spent in a microenvironment and for the penetration factor. Mean and standard deviation values parameterize the distributions. In this paper, Latin Hypercube sampling is used for the input distributions. The outcome of the framework is an estimate of the population exposure distribution for the selected air pollutant. The framework is best suited for averaging times from 24 h upwards. Sensitivity analyses can be performed to determine the most influential factors of exposure. The application of the framework is illustrated in two examples. The EXPOLIS PM(2.5) example uses microenvironment measurement and time-activity data from the EXPOLIS study to model PM(2.5) population exposure distributions in four European cities. The results are compared to the observed personal exposure distributions from the same study. The Dutch PM(10) example uses input data from several (Dutch) databases and from literature, and shows a more complex application of the framework for comparison of scenarios and subpopulations.

Measuring the accumulated hazards of smoking: global and regional estimates for 2000

OBJECTIVE

Current prevalence of smoking, even where data are available, is a poor proxy for cumulative hazards of smoking, which depend on several factors including the age at which smoking began, duration of smoking, number of cigarettes smoked per day, degree of inhalation, and cigarette characteristics such as tar and nicotine content or filter type.

METHODS

We extended the Peto-Lopez smoking impact ratio method to estimate accumulated hazards of smoking for different regions of the world. Lung cancer mortality data were obtained from the Global Burden of Disease mortality database. The American Cancer Society Cancer Prevention Study, phase II (CPS-II) with follow up for the years 1982 to 1988 was the reference population. For the global application of the method, never-smoker lung cancer mortality rates were chosen based on the estimated use of coal for household energy in each region.

RESULTS

Men in industrialised countries of Europe, North America, and the Western Pacific had the largest accumulated hazards of smoking. Young and middle age males in many regions of the developing world also had large smoking risks. The accumulated hazards of smoking for women were highest in North America followed by Europe.

CONCLUSIONS

In the absence of detailed data on smoking prevalence and history, lung cancer mortality provides a robust indicator of the accumulated hazards of smoking. These hazards in developing countries are currently more concentrated among young and middle aged males.

Particle concentration profile in a vertical displacement flow: a study in an industrial hall

The effect of displacement flow on the distribution of aerosol concentration was investigated in an industrial hall. According to the displacement ventilation principle, vertical upflow is accomplished by introducing fresh air, cooler than room air, into the occupied zone near floor level. The fresh air is introduced from low-velocity devices and heated by warm processes. This technique allows warm air contaminants to rise to the ceiling, and the rising plume is then exhausted close to the ceiling. This study presents the results of a field study conducted in an industrial environment. The aerosol properties and behavior, especially the vertical gradients, are characterized in a displacement flow field. The results indicate that the fine particles, less than 1 microm in diameter, are transported away from the breathing zone by the ventilation process. However, the air quality is significantly influenced by the emission source, and therefore the number concentration of fine and ultrafine (smaller than 0.1 microm in diameter) aerosol particles in the breathing zone was clearly elevated compared to that of the incoming clean air. The vertical gradients displayed clear size dependence; the strongest gradients were found for particles between 0.003 and 0.015 microm in diameter.

Epidemiological research on cancer with a focus on Europe

Cancer has been a growing public health problem throughout the last century. Cancer mortality rates in both sexes combined in the European Union (EU) reached a peak in 1988. Thereafter, they declined by 9.4% in 1998. Likewise, lung cancer rates in the EU for both sexes combined increased by 58% between 1960 and 1988, but declined by 14% in 1998. Over a third of the decline was accounted for by lung cancer alone and approximately half by the combination of tobacco-related neoplasms. About half of the decline in total cancer mortality not attributable to tobacco derived from the steady fall in mortality from gastric cancer. The remaining half, including favourable trends in colorectal, breast, testis and lymphoid neoplasms, can be at least in part attributed to advancements in cancer diagnosis and treatment. The major causes of cancer and hence the most important priorities for research will be reviewed, with a specific focus on European priorities for research.

Stop inhaling smoke: prevent coronary heart disease

Acute myocardial infarction (AMI) was rare a century ago and was diagnosed in few living patients prior to 1925. By 1950, it was the most common heart problem seen by clinicians. Thought at first to have been overlooked, there were many explanations offered for its neglect. Smoking, hypertension, and elevated cholesterol are associated with AMI, but of these only smoking should be considered a cause. Hypertension and hypercholesterolemia may be co-effects, perhaps of inflammation stimulated in the lung and blood vessels by smoking and air pollution, thus affecting vessels and arteries subjected to systemic blood pressure. Air pollution--the 20th century's other "big smoke"--deserves consideration as a 2nd cause. Auto exhaust blankets the world's cities. It consists of smoke and other effluents of petroleum vaporization and combustion that emanate from the crankcases and exhaust pipes of trucks and automobiles. The major living spaces (conurbations) of the world now imitate and exceed Los Angeles in their levels of air pollution. Auto exhaust gases fit the timeline, and their increasing amounts parallel the worldwide rise in coronary heart disease. Increasing doses of these chemicals imitate cigarette smoke and stimulate inflammation in the lungs. They appear to be absorbed into the blood, where they cause inflammation in blood vessels, increased blood pressure, and clogged coronary arteries. Avoidance is the obvious solution. Quit inhaling cigarette smoke and motor vehicle exhaust. The benefits have been shown and can be proved by intervention. The quest for clean air is hygienic-like avoiding water contaminated with feces was 150 yr ago. Clear air must be made a moral right. Its attainment requires a major revolution in priorities for energy use and lifestyle. Two types of smoke must be avoided. The world's most lethal disease.

Personal PM2.5 exposure and markers of oxidative stress in blood

Ambient particulate air pollution assessed as outdoor concentrations of particulate matter less than or equal to 2.5 micro m in diameter (PM(2.5)) in urban background has been associated with cardiovascular diseases at the population level. However, the significance of individual exposure and the involved mechanisms remain uncertain. We measured personal PM(2.5) and carbon black exposure in 50 students four times in 1 year and analyzed blood samples for markers of protein and lipid oxidation, for red blood cell (RBC) and platelet counts, and for concentrations of hemoglobin and fibrinogen. We analyzed protein oxidation in terms of gamma-glutamyl semialdehyde in hemoglobin (HBGGS) and 2-aminoadipic semialdehyde in hemoglobin (HBAAS) and plasma proteins (PLAAS), and lipid peroxidation was measured as malondialdehyde (MDA) in plasma. Median exposures were 16.1 micro g/m(3) for personal PM(2.5) exposure, 9.2 micro g/m(3) for background PM(2.5) concentration, and 8.1 X 10(-6)/m for personal carbon black exposure. Personal carbon black exposure and PLAAS concentration were positively associated (p < 0.01), whereas an association between personal PM(2.5) exposure and PLAAS was only of borderline significance (p = 0.061). A 3.7% increase in MDA concentrations per 10 micro g/m(3) increase in personal PM(2.5) exposure was found for women (p < 0.05), whereas there was no significant relationship for the men. Similarly, positive associations between personal PM(2.5)exposure and both RBC and hemoglobin concentrations were found only in women (p < 0.01). There were no significant relationships between background PM(2.5) concentration and any of the biomarkers. This suggests that exposure to particles in moderate concentrations can induce oxidative stress and increase RBCs in peripheral blood. Personal exposure appears more closely related to these biomarkers potentially related to cardiovascular disease than is ambient PM(2.5) background concentrations.

Air pollution: the "Heart" of the problem

Air pollution exposure is associated with an increased risk of acute and chronic cardiovascular mortality. Recent observations have implicated fine particulate matter (PM(2.5)) as one of the most important pollutants. Inhalation of PM(2.5) causes acute pulmonary inflammation and oxidative stress. The subsequent generation of a systemic inflammatory response could link air pollution exposure with the development of cardiovascular disease. Human experiments have demonstrated pro-arrhythmic alterations in cardiac autonomic tone, increased blood pressure, higher serum C-reactive protein levels, and alterations in blood rheology favoring coagulation following controlled pollution exposures or in relation to elevated ambient PM(2.5) levels. Recent studies have also uncovered several harmful impacts on the systemic vasculature, including the triggering of acute vasoconstriction and the enhanced development of atherosclerosis. Many questions, however, remain unanswered and future studies will be required to clarify the relevant biologic mechanisms and to identify the specific constituents responsible for mediating the adverse health impacts.

Personal PM2.5 exposure and markers of oxidative stress in blood

Ambient particulate air pollution assessed as outdoor concentrations of particulate matter less than or equal to 2.5 micro m in diameter (PM(2.5)) in urban background has been associated with cardiovascular diseases at the population level. However, the significance of individual exposure and the involved mechanisms remain uncertain. We measured personal PM(2.5) and carbon black exposure in 50 students four times in 1 year and analyzed blood samples for markers of protein and lipid oxidation, for red blood cell (RBC) and platelet counts, and for concentrations of hemoglobin and fibrinogen. We analyzed protein oxidation in terms of gamma-glutamyl semialdehyde in hemoglobin (HBGGS) and 2-aminoadipic semialdehyde in hemoglobin (HBAAS) and plasma proteins (PLAAS), and lipid peroxidation was measured as malondialdehyde (MDA) in plasma. Median exposures were 16.1 micro g/m(3) for personal PM(2.5) exposure, 9.2 micro g/m(3) for background PM(2.5) concentration, and 8.1 X 10(-6)/m for personal carbon black exposure. Personal carbon black exposure and PLAAS concentration were positively associated (p < 0.01), whereas an association between personal PM(2.5) exposure and PLAAS was only of borderline significance (p = 0.061). A 3.7% increase in MDA concentrations per 10 micro g/m(3) increase in personal PM(2.5) exposure was found for women (p < 0.05), whereas there was no significant relationship for the men. Similarly, positive associations between personal PM(2.5)exposure and both RBC and hemoglobin concentrations were found only in women (p < 0.01). There were no significant relationships between background PM(2.5) concentration and any of the biomarkers. This suggests that exposure to particles in moderate concentrations can induce oxidative stress and increase RBCs in peripheral blood. Personal exposure appears more closely related to these biomarkers potentially related to cardiovascular disease than is ambient PM(2.5) background concentrations.

Ambient air pollution and health

The adverse health effects of air pollution became widely acknowledged after severe pollution episodes occurred in Europe and North America before the 1960s. In these areas, pollutant levels have decreased. During the last 15 years, however, consistent results, mainly from epidemiological studies, have provided evidence that current air pollutant levels have been associated with adverse long- and short-term health effects, including an increase in mortality. These effects have been better studied for ambient particle concentrations but there is also substantial evidence concerning gaseous pollutants such as ozone, NO(2) and CO. Attempts to estimate the impact of air pollution effects on health in terms of the attributable number of events indicate that the ubiquitous nature of the exposure results in a considerable public health burden from relatively weak relative risks.

Relación a corto plazo de la contaminación atmosférica y la mortalidad en 13 ciudades españolas

BACKGROUND AND OBJECTIVE

EMECAM is a collaborative project that seeks to evaluate the short-term effects of air pollution on mortality in Spain.

MATERIAL AND METHOD

We collected data for air pollutants (particles and gases), daily mortality (total except external, cardiovascular and respiratory causes) and co-variables (temperature, humidity, influenza and calendar variables) in 13 Spanish cities. The magnitude of the association in every city was estimated using GAM under a Poisson distribution. Combined estimates for each cause and pollutant were obtained under 'fixed effects' and 'random effects'models.

RESULTS

An increase of 10 (g/m3 in the levels of the average of the concurrent and one day lag for black smoke was associated with a 0.8% (CI: 0.4-1.1) increase in mortality. The same increase in the concentration of SO2 was associated with a 0.5% (CI: 0.1-1.0) increase in daily deaths, and a 0.6% (CI: 0.3-0.8) increase in the case of NO2. An increase of 1 mg/m3 in the levels of CO was associated with an increase of 1.5% (CI: 0.5-2.6) in daily deaths.

CONCLUSIONS

There is a short-term association between increases of daily levels of air pollutants and the number of daily deaths in Spanish cities.

Contribution of environmental factors to cancer risk

Environmental carcinogens, in a strict sense, include outdoor and indoor air pollutants, as well as soil and drinking water contaminants. An increased risk of mesothelioma has consistently been detected among individuals experiencing residential exposure to asbestos, whereas results for lung cancer are less consistent. At least 14 good-quality studies have investigated lung cancer risk from outdoor air pollution based on measurement of specific agents. Their results tend to show an increased risk in the categories at highest exposure, with relative risks in the range 1.5-2.0, which is not attributable to confounders. Results for other cancers are sparse. A causal association has been established between exposure to environmental tobacco smoke and lung cancer, with a relative risk in the order of 1.2. Radon is another carcinogen present in indoor air which may be responsible for 1% of all lung cancers. In several Asian populations, an increased risk of lung cancer is present in women from indoor pollution from cooking and heating. There is strong evidence of an increased risk of bladder, skin and lung cancers following consumption of water with high arsenic contamination; results for other drinking water contaminants, including chlorination by-products, are inconclusive. A precise quantification of the burden of human cancer attributable to environmental exposure is problematic. However, despite the relatively small relative risks of cancer following exposure to environmental carcinogens, the number of cases that might be caused, assuming a causal relationship, is relatively large, as a result of the high prevalence of exposure.

The CAUSE model: a research-supported aid for physicians communicating with patients about cancer risk

"Talk to your doctor" may be one of the most common pieces of advice given to help patients manage cancer risk. In fact, though, the support given to physicians for talking with patients about cancer prevention is not extensive. To address this need, we propose a decision aid for physicians. The CAUSE model draws on existing research, identifying common sources of tension or confusion in physician patient interaction. Specifically, the model assists physicians in anticipating common barriers to effective communication and overcoming them to establish credibility, create awareness and understanding, gain agreement about solutions, and help patients enact solutions for the prevention of cancer.

Air pollution and its health impacts: the changing panorama

Urban air pollution levels are associated with increased mortality and cardiorespiratory morbidity. These health effects occur even at exposure levels below those stipulated in current air-quality guidelines, and it is unclear whether a safe threshold exists. Air pollution in Australia and New Zealand comes primarily from motor vehicle emissions, electricity generation from fossil fuels, heavy industry, and home heating using wood and coal. In individual patients a direct link between symptoms and air pollution exposure may be difficult to establish and may not change their clinical management. However, avoiding exposure during periods of peak pollution may be beneficial. Although there is some evidence that urban air pollution in Australia and New Zealand has been decreasing (through reduced car use, improved emission-control technology and use of more energy-efficient devices in the household and in industry), pollution levels are still unsatisfactory. Further reductions may prevent hundreds of cardiorespiratory hospital admissions and deaths each year.

The importance of population susceptibility for air pollution risk assessment: a case study of power plants near Washington, DC

In evaluating risks from air pollution, health impact assessments often focus on the magnitude of the impacts without explicitly considering the distribution of impacts across subpopulations. In this study, we constructed a model to estimate the magnitude and distribution of health benefits associated with emission controls at five older power plants in the Washington, DC, area. We used the CALPUFF atmospheric dispersion model to determine the primary and secondary fine-particulate-matter (< 2.5 micro m in aerodynamic diameter) concentration reductions associated with the hypothetical application of "Best Available Control Technology" to the selected power plants. We combined these concentration reductions with concentration-response functions for mortality and selected morbidity outcomes, using a conventional approach as well as considering susceptible subpopulations. Incorporating susceptibility had a minimal effect on total benefits, with central estimates of approximately 240 fewer premature deaths, 60 fewer cardiovascular hospital admissions (CHA), and 160 fewer pediatric asthma emergency room visits (ERV) per year. However, because individuals with lower education appear to have both higher background mortality rates and higher relative risks for air-pollution-related mortality, stratifying by educational attainment implies that 51% of the mortality benefits accrue among the 25% of the population with less than high school education. Similarly, diabetics and African Americans bear disproportionate shares of the CHA and ERV benefits, respectively. Although our ability to characterize subpopulations is constrained by the available information, our analysis demonstrates that incorporation of susceptibility information significantly affects demographic and geographic patterns of health benefits and enhances our understanding of individuals likely to benefit from emission controls.

Update on the health effects of outdoor air pollution

The number of studies conducted on the health effects of air pollution has increased exponentially. Important methodological advances include the application of novel observational study designs, in particular the multi-city design, and the development and application of airborne particle concentrators for use in experimental human exposure studies and toxicological studies. Experimental data are validating and providing insight into some surprising observational findings.

Epidemiology of lung cancer

This review article presents lung cancer epidemiology, describing main epidemiologic characteristics including epidemiological situation in cancer incidence, mortality and survival in Europe in comparison with situation in the Czech Republic. Influence of environmental and life style risk factors like smoking, passive smoking, risk factors of work environment, ionizing radiation, air pollution, nutrition and genetic and hormonal factors are discussed.

Primary prevention protects public health

It is widely accepted that epidemiological data provide the only reliable evidence of a carcinogenic effect in humans, but epidemiology is unable to provide early warning of a cancer risk. The experimental approach to carcinogenicity can ascertain and predict potential cancer risks to humans in time for primary prevention to be successful. Unfortunately, only in rare instances were experimental data considered sufficiently convincing per se to stimulate the adoption of preventive measures. The experimental testing of environmental agents is the second line of defense against potential human carcinogens. The first line is the testing of synthesized agents, be these pesticides, medical drugs, or industrial chemical/physical agents, at the time of their development. We do not know, however, how many substances have been prevented from entering the environment because most tests are carried out by commercial or private laboratories and results are rarely released. A better understanding of the mechanisms underlying the sequence of events of the carcinogenesis process will eventually lead to a more accurate characterization and quantification of risks. However, the ways that mechanistic data have been used lately for evaluating evidence of carcinogenicity have not necessarily meant that the evaluations were more closely oriented toward public health. A tendency has surfaced to dismiss the relevance of long-term carcinogenicity studies. In the absence of absolute certainty, rarely if ever reached in biology, it is essential to adopt an attitude of responsible caution, in line with the principles of primary prevention, the only one that may prevent unlimited experimentation on the entire human species.

The origin, fate, and health effects of combustion by-products: a research framework

Incomplete combustion processes can emit organic pollutants, metals, and fine particles. Combustion by-products represent global human and environmental health challenges that are relevant not only in heavily industrialized nations, but also in developing nations where up to 90% of rural households rely on unprocessed biomass fuels for cooking, warmth, and light. These issues were addressed at the Seventh International Congress on Combustion By-Products, which convened 4-6 June 2001 in Research Triangle Park, North Carolina. This congress included a diverse group of multidisciplinary researchers and practitioners who discussed recent developments and future goals in the control of combustion by-products and their effects of exposure on human and ecologic health. Participants recommended that interdisciplinary, coordinated research efforts should be focused to capitalize on the important potential synergisms between efforts to reduce the adverse human health effects linked to exposures to combustion by-products and broader efforts to reduce greenhouse gas emissions and save energy through efficiency. In this article we summarize the principal findings and recommendations for research focus and direction.

Air pollution and health

The health effects of air pollution have been subject to intense study in recent years. Exposure to pollutants such as airborne particulate matter and ozone has been associated with increases in mortality and hospital admissions due to respiratory and cardiovascular disease. These effects have been found in short-term studies, which relate day-to-day variations in air pollution and health, and long-term studies, which have followed cohorts of exposed individuals over time. Effects have been seen at very low levels of exposure, and it is unclear whether a threshold concentration exists for particulate matter and ozone below which no effects on health are likely. In this review, we discuss the evidence for adverse effects on health of selected air pollutants.

Hazardous air pollutants and asthma

Asthma has a high prevalence in the United States, and persons with asthma may be at added risk from the adverse effects of hazardous air pollutants (HAPs). Complex mixtures (fine particulate matter and tobacco smoke) have been associated with respiratory symptoms and hospital admissions for asthma. The toxic ingredients of these mixtures are HAPs, but whether ambient HAP exposures can induce asthma remains unclear. Certain HAPs are occupational asthmagens, whereas others may act as adjuncts during sensitization. HAPs may exacerbate asthma because, once sensitized, individuals can respond to remarkably low concentrations, and irritants lower the bronchoconstrictive threshold to respiratory antigens. Adverse responses after ambient exposures to complex mixtures often occur at concentrations below those producing effects in controlled human exposures to a single compound. In addition, certain HAPs that have been associated with asthma in occupational settings may interact with criteria pollutants in ambient air to exacerbate asthma. Based on these observations and past experience with 188 HAPs, a list of 19 compounds that could have the highest impact on the induction or exacerbation of asthma was developed. Nine additional compounds were identified that might exacerbate asthma based on their irritancy, respirability, or ability to react with biological macromolecules. Although the ambient levels of these 28 compounds are largely unknown, estimated exposures from emissions inventories and limited air monitoring suggest that aldehydes (especially acrolein and formaldehyde) and metals (especially nickel and chromium compounds) may have possible health risk indices sufficient for additional attention. Recommendations for research are presented regarding exposure monitoring and evaluation of biologic mechanisms controlling how these substances induce and exacerbate asthma.

Potential technology for studying dosimetry and response to airborne chemical and biological pollutants

Advances in computational, and imaging techniques have enabled the rapid development of three-dimensional (3-D) models of biological systems in unprecedented detail. Using these advances, 3-D models of the lungs and nasal passages of the rat and human are being developed to ultimately improve predictions of airborne pollutant dosimetry. Techniques for imaging the respiratory tract by magnetic resonance imaging (MRI) were developed to improve the speed and accuracy of geometric data collection for mesh reconstruction. The MRI resolution is comparable to that obtained by manual measurements but at much greater speed and accuracy. Newly developed software (NWGrid) was utilized to translate imaging data from MR into 3-D mesh structures. Together, these approaches significantly reduced the time to develop a 3-D model. This more robust airway structure will ultimately facilitate modeling gas or vapor exchange between the respiratory tract and vasculature as well as enable linkages of dosimetry with cell response models. The 3-D, finite volume, viscoelastic mesh structures form the geometric basis for computational fluid dynamics modeling of inhalation, exhalation and the delivery of individual particles (or concentrations of gas or vapors) to discrete regions of the respiratory tract. The ability of these 3-D models to resolve dosimetry at such a high level of detail will require new techniques to measure regional airflows and particulate deposition for model validation.