Adverse health effects of outdoor air pollutants

Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.     

Cancer risk assessment of selected hazardous air pollutants in Seattle

The risk estimates calculated from the conventional risk assessment method usually are compound specific and provide limited information for source-specific air quality control. We used a risk apportionment approach, which is a combination of receptor modeling and risk assessment, to estimate source-specific lifetime excess cancer risks of selected hazardous air pollutants. We analyzed the speciated PM(2.5) and VOCs data collected at the Beacon Hill in Seattle, WA between 2000 and 2004 with the Multilinear Engine to first quantify source contributions to the mixture of hazardous air pollutants (HAPs) in terms of mass concentrations. The cancer risk from exposure to each source was then calculated as the sum of all available species' cancer risks in the source feature. We also adopted the bootstrapping technique for the uncertainty analysis. The results showed that the overall cancer risk was 6.09 x 10(-5), with the background (1.61 x 10(-5)), diesel (9.82 x 10(-6)) and wood burning (9.45 x 10(-6)) sources being the primary risk sources. The PM(2.5) mass concentration contributed 20% of the total risk. The 5th percentile of the risk estimates of all sources other than marine and soil were higher than 110(-6). It was also found that the diesel and wood burning sources presented similar cancer risks although the diesel exhaust contributed less to the PM(2.5) mass concentration than the wood burning. This highlights the additional value from such a risk apportionment approach that could be utilized for prioritizing control strategies to reduce the highest population health risks from exposure to HAPs.     

Ecological effects of sulfur dioxide,fluorides, and minor air pollutants: recent trends and research needs

The regulation of the emissions of 'traditional' primary air pollutants (fluorides, sulfur dioxide) has changed the pattern of exposure of ecological systems, with greatly reduced exposure close to sources, but with a smaller effect in some remote areas. Measurements show that recovery is occurring at some sites, in fresh water chemistry (reduced acidity) and in sensitive biota (sustainable fish populations). However, the pattern of change in exposure has not always been simply related to emission reductions. An understanding of responses to recent changes will improve our predictions of the response to future emission changes, both locally and globally. As exposure to 'traditional' pollutants is reduced, the potential for other pollutants to have effects becomes more evident. In the aqueous phase, we need to understand the role of soluble and suspended organics, but this also means explicit recognition of the possibility of phase exchange, and the role of photolytic reactions on plant, soil, and water surfaces. Do highly reactive free radicals in the atmosphere, formed by the action of sunlight on volatile organic compounds, have direct effects on plants? Organic compounds and heavy metals may be bioactive as gases and particles, but for many potentially toxic compounds, the experimental evidence for biotic response is very limited. To evaluate the potential effects of pollutants, we need to understand the pathways by which airborne pollutants enter and react within ecosystems. For vegetation, we have to consider bidirectional fluxes, and distinguish among uptake through stomata, through leaf surfaces, or through roots. There are several challenges for the future. (1) Can we devise experiments that permit exposure of vegetation to gases, particles, and/or aqueous pollutants at 'realistic' concentrations? (2) Can we include the potential interactions with photolytically derived free radicals, and the dynamics of exchange? (3) How do we allow for responses to pollutant mixtures, or the simultaneous exposure to pollutants in gas, particle, and aqueous phases? The recognition of the importance of the dynamic exchange of pollutants between phases will be the key to the development of effective experimental approaches to evaluating cause-effect relationships between pollutant mixtures and ecosystem responses.     

Genetic consequences of radioactive contamination by the Chernobyl fallout to agricultural crops

The genetic consequences of radioactive contamination by the fallout to agricultural crops after the accident at the Chernobyl NPP in 1986 have been studied. In the first, acute, period of this accident, when the absorbed dose was primarily due to external beta- and gamma-irradiation, the radiation injury of agricultural crops, according to the basic cytogenetic tests, resembled the effect produced by acute gamma-irradiation at comparable doses. The yield of cytogenetic damage in leaf meristem of plants grown in the 10-km zone of the ChNPP in 1987-1989 (the period of chronic, lower level radiation exposure) was shown to be enhanced and dependent on the level of radioactive contamination. The rate of decline with time in cytogenetic damage induced by chronic exposure lagged considerably behind that of the radiation exposure. Analysis of genetic variability in three sequential generations of rye and wheat revealed increased cytogenetic damage in plants exposed to chronic irradiation during the 2nd and 3rd years.     

Immunotoxic effects of environmental pollutants in marine mammals

Due to their marine ecology and life-history, marine mammals accumulate some of the highest levels of environmental contaminants of all wildlife. Given the increasing prevalence and severity of diseases in marine wildlife, it is imperative to understand how pollutants affect the immune system and consequently disease susceptibility. Advancements and adaptations of analytical techniques have facilitated marine mammal immunotoxicology research. Field studies, captive-feeding experiments and in vitro laboratory studies with marine mammals have associated exposure to environmental pollutants, most notable polychlorinated biphenyls (PCBs), organochlorine pesticides and heavy metals, to alterations of both the innate and adaptive arms of immune systems, which include aspects of cellular and humoral immunity. For marine mammals, reported immunotoxicology endpoints fell into several major categories: immune tissue histopathology, haematology/circulating immune cell populations, functional immune assays (lymphocyte proliferation, phagocytosis, respiratory burst, and natural killer cell activity), immunoglobulin production, and cytokine gene expression. Lymphocyte proliferation is by far the most commonly used immune assay, with studies using different organic pollutants and metals predominantly reporting immunosuppressive effects despite the many differences in study design and animal life history. Using combined field and laboratory data, we determined effect threshold levels for suppression of lymphocyte proliferation to be between < 0.001–10 ppm for PCBs, 0.002–1.3 ppm for Hg, 0.009–0.06 for MeHg, and 0.1–2.4 for cadmium in polar bears and several pinniped and cetacean species. Similarly, thresholds for suppression of phagocytosis were 0.6–1.4 and 0.08–1.9 ppm for PCBs and mercury, respectively. Although data are lacking for many important immune endpoints and mechanisms of specific immune alterations are not well understood, this review revealed a systemic suppression of immune function in marine mammals exposed to environmental contaminants. Exposure to immunotoxic contaminants may have significant population level consequences as a contributing factor to increasing anthropogenic stress in wildlife and infectious disease outbreaks.     

Quantifying disturbance effects on vegetation carbon pools in mountain forests based on historical data

Although the terrestrial carbon budget is of key importance for atmospheric CO₂ concentrations, little is known on the effects of management and natural disturbances on historical carbon stocks at the regional scale. We reconstruct the dynamics of vegetation carbon stocks and flows in forests across the past 100 years for a valley in the eastern Swiss Prealps using quantitative and qualitative information from forest management plans. The excellent quality of the historical information makes it possible to link dynamics in growing stocks with high-resolution time series for natural and anthropogenic disturbances. The results of the historical reconstruction are compared with modelled potential natural vegetation. Forest carbon stock at the beginning of the twentieth century was substantially reduced compared to natural conditions as a result of large scale clearcutting lasting until the late nineteenth century. Recovery of the forests from this unsustainable exploitation and systematic forest management were the main drivers of a strong carbon accumulation during almost the entire twentieth century. In the 1990s two major storm events and subsequent bark beetle infestations significantly reduced stocks back to the levels of the mid-twentieth century. The future potential for further carbon accumulation was found to be strongly limited, as the potential for further forest expansion in this valley is low and forest properties seem to approach equilibrium with the natural disturbance regime. We conclude that consistent long-term observations of carbon stocks and their changes provide rich information on the historical range of variability of forest ecosystems. Such historical information improves our ability to assess future changes in carbon stocks. Further, the information is vital for better parameterization and initialization of dynamic regional scale vegetation models and it provides important background for appropriate management decisions.     

The effects of woodburning on the indoor residential air quality

Data from suburban residences in the Boston metropolitan area reveal a potential adverse impact on indoor air quality from woodburning in woodstoves and fireplaces. Ambient pollutant concentrations at each residence were compared to corresponding pollutant levels indoors at three locations (kitchen, bedroom, and activity room). Individual gaseous pollutant samples were averaged on an hourly basis while 24-h integrated samples of particulate matter were obtained. Ten gaseous pollutants were sampled along with total suspended particulates (TSP). Chemical analyses further determined ten components of TSP including trace metals, benzo-a-pyrene(B)aP, respirable suspended particulates (RSP), and water soluble sulfates and nitrates. Monitoring lasted two weeks at each residence and was conducted under occupied, real-life, conditions. Observed, elevated indoor concentrations of TSP, RSP, and BaP are attributed to woodburning. Data indicate that average indoor TSP concentrations during woodburning periods were about three times corresponding levels during nonwoodburning periods. The primary 24-h national ambient air quality standard (NAAQS) for TSP was exceeded once indoors during fireplace use, and the secondary, 24-h TSP NAAQS, was also exceeded indoors by RSP concentrations. Indoor BaP concentrations during woodstove use averaged five times more than during nonwoodburning periods. At this stage, results are only indicative, but the potential impact from elevated indoor concentrations of TSP, RSP, and BaP, attributed to woodburning, may have long-term health implications.     

Estimating the total exposure to air pollutants for different population age groups in Hong Kong

Given that Hong Kong is one of the most densely populated cities in the world, the exposure of the Hong Kong people is one of the interesting research areas. In this study, an indirect approach was used to estimate the exposure to nitrogen dioxide (NO2), respiratory dust (PM10) and carbon monoxide (CO) pollutants experienced by different age groups of people in Hong Kong. The average concentrations of the 20 major microenvironments obtained from our measurement survey data, together with the people activity pattern data obtained from 7-day recall questionnaires, were used to predict frequency distributions to exposure assessment. Our results showed that Hong Kong people spent more than 86% of their time indoors. Homes were shown to be the one of the major exposure sites to NO2, CO and PM10 for all age groups. Our results also indicate that the 24-h NO2 exposure for individuals, irrespective of age, spending more than 2 h in commuting daily, was observed to be exceeding the 24-h NO2 exposure standards. This study was one of the pioneering studies with valuable contribution for modeling the estimates of exposures to NO2, PM10 and CO of different age groups in Hong Kong.     

Recent progress in developing and using personal monitors to measure human exposure to air pollutants

Within the last two years, great progress has been made in the field of personal air quality monitors. Improvements in pump design, miniaturization, adsorption techniques, and new collection principles have produced about a dozen sensitive monitors capable of being used by the general public to measure their normal everyday exposure to many toxic or carcinogenic compounds. This article reviews recent progress in this field, particularly as it relates to U.S. Environmental Protection Agency programs.     

Spatial assessment of climate change effects on crop suitability for major plantation crops in Sri Lanka

Climate change is the main global challenge of this century; it is therefore imperative to identify its effects on agriculture in developing countries. This research makes spatial assessment of climate change effect on major plantation crops in Sri Lanka, with emphasis on crop suitability of tea, rubber, and coconut. Geo-referenced maps of spatial and temporal changes in crop suitability and production potentials are generated and compared. Data pertaining to six agro-ecological zones under the study area are analyzed for a period of 1980–2007. Crop suitability maps are generated amalgamating yield maps and climatic factors maps using AHP in multi-criteria analysis under two time frames of 1980–1992 and 1993–2007. Percent change in crop suitability and crop yield classes is calculated based on five crop suitability and five crop yield classes during two time frames. Dynamics of climatic parameters and crop yield are recognized using geo-referenced maps. The suitability maps of the two time frames are compared to identify the changes with each crop in conjunction with changes in the prevailing climate and yield. Geographic shift of suitability, yield, and climate classes are examined. Net gain or loss in crop production is quantified. Long-term annual rainfall significantly decreased in mid-country wet zone, whereas the mean temperature of the study area increased by 1.4°C. Results clearly showed that the climate and yield can be meaningfully related to the crop suitability and management.     

Assessing the genotoxicity of urban air pollutants in Varanasi City using Tradescantia micronucleus (Trad-MCN) bioassay

In the present study Tradescantia micronucleus (Trad-MCN) bioassay was performed to assess the genotoxicity of air pollutants in Varanasi City. The experiment was performed during October 2006 to April 2007. For Tradescantia micronucleus (Trad-MCN) bioassay four sites were selected, three in the city having different traffic characteristics and one control site virtually free from traffic intervention. Twenty young Tradescantia pallida inflorescences were collected from each sampling site during the study period and micronuclei frequencies were determined in early tetrads of pollen mother cells and expressed as MCN/100 tetrads. During the same period the concentration of different air pollutants were also measured. Tradescantia micronucleus (Trad-MCN) bioassay showed that the plants kept in areas having higher traffic emissions evidence higher micronuclei frequencies than samples kept at control site. The study indicates that in situ biomonitoring using higher plants may be useful for characterizing genotoxic air pollutants in areas even without any sophisticated instrument.     

Using air pollution based community clusters to explore air pollution health effects in children

To study respiratory health effects of long-term exposure to ambient air pollutant mixture, we observed 7058 school children 5-16 years of age living in the four Chinese cities of Lanzhou, Chongqing, Wuhan, and Guangzhou. These children were enrolled from elementary schools located in eight districts, one urban district and one suburban district in each of the above cities. Ambient levels of PM(2.5), PM(10-2.5), total suspended particles (TSP), SO(2), and NO(x) were measured in these districts from 1993 to 1996. Based on a cluster analysis of arithmetic mean concentrations of PM(2.5), PM(10-2.5), (TSP-PM(10)), SO(2), and NO(x), we classified these children into four ordinal categories of exposure to ambient air pollutant mixtures. We tested for exposure-response relationships using logistic regression models, controlling for relevant covariates. We observed monotonic, positive relationships of exposure to the pollutant mixture with prevalence rates of cough with phlegm and wheeze. Other outcomes were not associated with the exposure in a monotonic exposure-response pattern. Even so, odds ratios for cough, phlegm, bronchitis, and asthma in the higher exposure district clusters were all higher than in the lowest exposure district cluster. We found evidence that exposure to the pollutant mixtures had adverse effects on children living in the four Chinese cities.     

The potential impact of environmental variation on the concentrations and ecological effects of pollutants in a marine avian top predator

Concentrations of organochlorine contaminants (OCs) and associations between OCs and fitness components were examined in great black-backed gulls (Larus marinus) in three colonies along the coast of northern Norway. In one of the colonies, data were collected in two subsequent seasons. Concentrations of four OCs (HCB, oxychlordane, DDE and PCB) were measured in blood (n=260) and fitness components (reproductive variables and adult return rate between breeding seasons) were recorded. In the first year, in two of the colonies, body condition and reproductive performance among the gulls were poor compared to the third colony, suggesting spatial variation in environmental conditions, especially food availability. However, in the third colony, body condition and reproductive performance were even better in the second season; i.e. environmental conditions varied temporally. OC residues were higher in the colonies where environmental conditions were poor, but much of this variation was explained by differences in body condition among colonies. Moreover, concurrent with improved body condition from one season to the next, the concentrations of OCs were halved. In the two colonies where environmental conditions were poor, female OC residues were negatively related to egg-laying date, egg size and nesting success, and in the colony where the concentrations of OC were highest, gulls with elevated DDE residues had low probability of returning between breeding seasons. In comparison, in the colony where environmental conditions were better in the first year, other types of adverse relationships between OCs and fitness components were found; i.e. chicks from females with high OC concentrations were in poor condition at hatching, suggesting maternal transfer of OCs to the eggs, and males with high OC residues had poor nesting success and chick survival, suggesting OC-mediated behavioural changes. With improved environmental conditions and lower OC concentrations in the second season, no significant adverse relationships between OCs and fitness components were found. This study thus suggests that there are complex interrelationships between both concentrations and ecological effects of OCs, and the environment, indicating that effects of OCs in nature may only be assessed after considering environmental variation.     

Assessing potential secondary effects of countermeasures in agricultural systems: a review.

Secondary effects are defined as any positive or negative impacts resulting from the application of countermeasures other than radiological benefits or direct costs. They are categorised into environmental, radioecological, economic and social effects. Impacts on the environment may include changes in water, air and soil pollution or in the conservation and amenity value of an area. Radioecological effects occur when the countermeasure unintentionally alters the behaviour of the target radionuclide or any other radionuclide present. Economic effects may range from changes in agricultural income to environmental costs (e.g. impact of soil erosion on fisheries). Social effects relate to the acceptability of countermeasures, for example in terms of consumer confidence and animal welfare. Recent research into the identification and assessment of secondary effects is summarised. Non-quantitative and quantitative approaches are explained and formal evaluation procedures involving decision matrices and decision support systems are introduced. Examples of recent experimental and modelling work focusing on radiocaesium are given for the following countermeasures: soil application of potassium, administration of AFCF to livestock and ploughing techniques.     

Health effects of indoor air pollution: Synergistic effects of nitrogen dioxide and a respirable aerosol

Comparative studies of the effects of various air pollutants on lung collagen biosynthesis have been performed. A hitherto unexpected synergism between the oxidant air pollutants ozone or nitrogen dioxide and a respirable-sized aerosol of ammonium sulfate was observed during controlled exposures of rats to these substances. In an assay system, measuring collagen biosynthesis by lung minces prepared from rats exposed for 1 week to either filtered air or to these pollutants gases, dose-response curves to either O₃ or NO₂ are altered in the presence of 5 mg/m³ of (NH₄)₂SO₄ aerosol. These observations may have broad implications for the appropriate evaluation of laboratory data in the setting of ambient air quality standards and/or the setting of threshold limit values for maintenance of occupational health and safety.     

New international long-term ecological research on air pollution effects on the Carpathian Mountain forests,Central Europe

An international cooperative project on distribution of ozone in the Carpathian Mountains, Central Europe was conducted from 1997 to 1999. Results of that project indicated that in large parts of the Carpathian Mountains, concentrations of ozone were elevated and potentially phytotoxic to forest vegetation. That study led to the establishment of new long-term studies on ecological changes in forests and other ecosystems caused by air pollution in the Retezat Mountains, Southern Carpathians, Romania and in the Tatra Mountains, Western Carpathians on the Polish-Slovak border. Both of these important mountain ranges have the status of national parks and are Man & the Biosphere Reserves. In the Retezat Mountains, the primary research objective was to evaluate how air pollution may affect forest health and biodiversity. The main research objective in the Tatra Mountains was to evaluate responses of natural and managed Norway spruce forests to air pollution and other stresses. Ambient concentrations of ozone (O(3)), sulfur dioxide (SO(2)), nitrogen oxides (NO(x)) as well as forest health and biodiversity changes were monitored on densely distributed research sites. Initial monitoring of pollutants indicated low levels of O(3), SO(2), and NO(x) in the Retezat Mountains, while elevated levels of O(3) and high deposition of atmospheric sulfur (S) and nitrogen (N) have characterized the Tatra Mountains. In the Retezat Mountains, air pollution seems to have little effect on forest health; however, there was concern that over a long time, even low levels of pollution may affect biodiversity of this important ecosystem. In contrast, severe decline of Norway spruce has been observed in the Tatra Mountains. Although bark beetle seems to be the immediate cause of that decline, long-term elevated levels of atmospheric N and S depositions and elevated O(3) could predispose trees to insect attacks and other stresses. European and US scientists studied pollution deposition, soil and plant chemistry, O(3)-sensitive plant species, forest insects, and genetic changes in the Retezat and Tatra Mountains. Results of these investigations are presented in a GIS format to allow for a better understanding of the changes and the recommendations for effective management in these two areas.     

Effects of seven organic pollutants on soil nematode Caenorhabditis elegans

Caenorhabditis elegans is a free-living soil nematode that is commonly used as a model for toxicity tests. The aim of this study was to investigate the toxicity of seven organic pollutants: four azaarenes (quinoline, acridine, phenazine, and 1,10-phenanthroline), short-chain chlorinated paraffins, and two organochlorinated pesticides (toxaphene and hexachlorobenzene). The exposure to all chemicals was carried out in three test media (soil, agar, and aquatic medium), and adult mortality was evaluated after 24 and 48 h. Toxaphene was the most toxic substance with LC(50) (48 h) of 379 mg/kg in the soil and 0.2 mg/L in the aquatic medium. Quinoline was the most toxic chemical in agar test with LC(50) (48 h) of 10 mg/L. HCB showed a very low toxicity in all tests, maybe due to its very low water solubility. Longer than 24-h test duration was found necessary for getting more correct data on toxicity. In comparison with other studies, C. elegans was less sensitive than other soil invertebrates. Different response might be attributed to different exposure routes and shorter test duration. Equilibrium partitioning theory was used to calculate K(oc) from results of soil and aquatic tests but this approach was found not working. Our results suggest that the tests with nematode C. elegans should be included to the battery of tests for risk assessment of POPs in soil.     

Exploring uncertainty of the change from ICD-9 to ICD-10 on acute mortality effects of air pollution

The change in ICD coding from ICD-9 to ICD-10 may produce inconsistencies and discontinuities in cause-specific mortality, thus impacting on effects estimates of air pollution on mortality. The current study was conducted in Wuhan, China. We examined the concordant rates and Kappa statistics using the mortality data from the year 2002 coded with both ICD-9 and ICD-10 codes and compared the estimated effects of air pollution using the Generalized Additive Model in R. We found high concordant rates (>99.3%) and Kappa statistics close to 1.0 (>0.98). Little difference was identified in the estimated effects of air pollution on daily cardiovascular, stroke, cardiac, cardiopulmonary, and respiratory mortality. This study provides evidence that, based on the wide definitions of cause-specific morality typically used in the studies of time-series air pollution mortality, the change in the ICD coding does not significantly affect the estimated effects of air pollution.     

Evaluation of genotoxic and non-genotoxic effects of organic air pollution using in vitro bioassays

In this study, organic extracts of total suspended particles (TSP) and the particulate matter (PM) with the size below 2.5 microm (PM(2.5)) combined with organic extracts of the gas phase (GP) collected at two urban and two background localities were analyzed with a bacterial genotoxicity test, SOS chromotest, and an in vitro test for the dioxin toxicity determination, using a modified cell-line of rat hepatoma H4IIE.luc. In addition, the samples of TSP and GP were analyzed for PAHs contents. The PAHs concentrations and both of the toxic activities at the urban localities were much higher than ones at the background localities. Predominantly, traffic was a source of the urban air pollution there which was also confirmed by the evaluation of portions of certain PAHs (BaP/BPE, PYR/BaP) at the localities. On the other hand, the background localities were apparently affected by a long-distance transport of the pollutants from urban and industrial centers. The results of the bioassays indicated potential health risks for the population exposed to the organic air pollutants, especially at the urban localities. Based on the collected samples, distribution of the organic pollutants with the toxic effects in the air was evaluated. The significant portion of the direct genotoxins was bound to the particles larger than 2.5 microm. On the contrary, the indirect genotoxins were bound predominantly to the particles with the size below 2.5 microm. However, in the urban air they may be also bound to the larger particles, as well. While the direct genotoxicity may be related with the presence of PAH-derivatives as well as some polar organic pollutants, the indirect genotoxicity is related with the detected carcinogenic PAHs. But besides the above specified pollutants it is also necessary to consider the presence of other toxic components of the complex organic air pollution mixture that may also show potential health risks. This study demonstrates application of the combination of the screening bioassays for the evaluation of organic air pollution and identification of its health risks.