Low level of antibodies to the oral bacterium Tannerella forsythia predicts bladder cancers and Treponema denticola predicts colon and bladder cancers: A prospective cohort study

This study explores the risk for cancer by level of antibodies to the anaerobe oral bacteria of periodontitis Tannerella forsythia (TF), Porphyromonas gingivalis (PG), and Treponema denticola (TD) all three collectively termed the red complex, and the facultative anaerobe bacterium Aggregatibacter actinomycetemcomitans (AA). The prospective cohort, the Oslo II-study from 2000, the second screening of the Oslo study of 1972/73, has been followed for 17 ½ years with regard to cancer incidence and mortality. A random sample of 697 elderly men comprised the study cohort. The antibody results measured by enzyme linked immunosorbent assay (ELISA) were used in the Cox proportional hazards analyses, and quartile risk on cancer incidence in a 17 ½ years follow-up. Among the 621 participants with no prior cancer diagnoses, 221 men developed cancer. The incidence trend was inverse, and the results are shown as 1^st quartile of highest value and 4^th as lowest of antibody levels. The results of the Cox proportional regression analyses showed that TF inversely predicts bladder cancer (n = 22) by Hazard Ratio (HR) = 1.71 (95% CI: 1.12, 2.61). TD inversely predicts colon cancer (n = 26) by HR = 1.52 (95% CI: 1.06, 2.19) and bladder cancer (n = 22) by HR = 1.60 (95% CI: 1.05, 2.43). Antibodies to two oral bacteria, TF and TD, showed an inverse risk relationship with incidence of specific cancers: TF bladder cancer, TD bladder and colon cancer. Lowered immunological response to the oral infection, periodontitis, is shown to be a risk factor in terms of cancer aetiology.

Review of industry reports on EU priority tobacco additives part A: Main outcomes and conclusions

The European Union Tobacco Products Directive (EU TPD) mandates enhanced reporting obligations for tobacco manufacturers regarding 15 priority additives. Within the Joint Action on Tobacco Control (JATC), a review panel of independent experts was appointed for the scientific evaluation of the additive reports submitted by a consortium of 12 tobacco manufacturers. As required by the TPD, the reports were evaluated based on their comprehensiveness, methodology and conclusions. In addition, we evaluated the chemical, toxicological, addictive, inhalation facilitating and flavoring properties of the priority additives based on the submitted reports, supplemented by the panel's expert knowledge and some independent literature. The industry concluded that none of the additives is associated with concern. Due to significant methodological limitations, we question the scientific validity of these conclusions and conclude that they are not warranted. Our review demonstrates that many issues regarding toxicity, addictiveness and attractiveness of the additives have not been sufficiently addressed, and therefore concerns remain. For example, menthol facilitates inhalation by activation of the cooling receptor TRPM8. The addition of sorbitol and guar gum leads to a significant increase of aldehydes that may contribute to toxicity and addictiveness. Titanium dioxide particles (aerodynamic diameter <10 µm) are legally classified as carcinogenic when inhaled. For diacetyl no report was provided. Overall, the industry reports were not comprehensive, and the information presented provides an insufficient basis for the regulation of most additives. We, therefore, advise MS to consider alternative approaches such as the precautionary principle.

Review of industry reports on EU priority tobacco additives part B: Methodological limitations

The Tobacco Products Directive (TPD) defines enhanced reporting obligations applying to 15 priority additives added to cigarettes and roll-your-own tobacco. A consortium of 12 international tobacco companies submitted 14 reports that were reviewed by an independent scientific body within the Joint Action on Tobacco Control (JATC). The reports were evaluated in accordance with the TPD with regard to their comprehensiveness, methodology and conclusions. Here we present their significant identified methodological limitations.

The toxicological and chemical evaluation in the industry reports was mainly based on comparative testing, which lacks discriminative power for products with high toxicity and variability, like cigarettes. The literature reviews were biased, the comparative chemical studies did not assess previously identified pyrolysis products, the toxicological evaluation did not include the assessment of inhalation toxicity, and pyrolysis products were not assessed in terms of toxicity, including their genotoxic and carcinogenic potential. For both chemistry and toxicity testing, the statistical approach applied to test the difference between test and additive-free control cigarettes resulted in a high chance of false negatives. The clinical study for inhalation facilitation and nicotine uptake had limitations concerning study design and statistical analysis, while addictiveness was not assessed. Finally, the methodology used to assess characterizing flavors was flawed.

In conclusion, there are significant limitations in the methodology applied by the industry. Therefore, the provided reports are of insufficient quality and are clearly not suitable to decide whether a priority additive should be banned in tobacco products according to the TPD.

Long-term exposure to low ambient air pollution concentrations and mortality among 28 million people: results from seven large European cohorts within the ELAPSE project

BACKGROUND

Long-term exposure to ambient air pollution has been associated with premature mortality, but associations at concentrations lower than current annual limit values are uncertain. We analysed associations between low-level air pollution and mortality within the multicentre study Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE).

METHODS

In this multicentre longitudinal study, we analysed seven population-based cohorts of adults (age ≥30 years) within ELAPSE, from Belgium, Denmark, England, the Netherlands, Norway, Rome (Italy), and Switzerland (enrolled in 2000-11; follow-up until 2011-17). Mortality registries were used to extract the underlying cause of death for deceased individuals. Annual average concentrations of fine particulate matter (PM_2·5), nitrogen dioxide (NO₂), black carbon, and tropospheric warm-season ozone (O₃) from Europe-wide land use regression models at 100 m spatial resolution were assigned to baseline residential addresses. We applied cohort-specific Cox proportional hazard models with adjustment for area-level and individual-level covariates to evaluate associations with non-accidental mortality, as the main outcome, and with cardiovascular, non-malignant respiratory, and lung cancer mortality. Subset analyses of participants living at low pollutant concentrations (as per predefined values) and natural splines were used to investigate the concentration-response function. Cohort-specific effect estimates were pooled in a random-effects meta-analysis.

FINDINGS

We analysed 28 153 138 participants contributing 257 859 621 person-years of observation, during which 3 593 741 deaths from non-accidental causes occurred. We found significant positive associations between non-accidental mortality and PM_2·5, NO₂, and black carbon, with a hazard ratio (HR) of 1·053 (95% CI 1·021-1·085) per 5 μg/m³ increment in PM_2·5, 1·044 (1·019-1·069) per 10 μg/m³ NO₂, and 1·039 (1·018-1·059) per 0·5 × 10^-5/m black carbon. Associations with PM_2·5, NO₂, and black carbon were slightly weaker for cardiovascular mortality, similar for non-malignant respiratory mortality, and stronger for lung cancer mortality. Warm-season O₃ was negatively associated with both non-accidental and cause-specific mortality. Associations were stronger at low concentrations: HRs for non-accidental mortality at concentrations lower than the WHO 2005 air quality guideline values for PM_2·5 (10 μg/m³) and NO₂ (40 μg/m³) were 1·078 (1·046-1·111) per 5 μg/m³ PM_2·5 and 1·049 (1·024-1·075) per 10 μg/m³ NO₂. Similarly, the association between black carbon and non-accidental mortality was highest at low concentrations, with a HR of 1·061 (1·032-1·092) for exposure lower than 1·5× 10^-5/m, and 1·081 (0·966-1·210) for exposure lower than 1·0× 10^-5/m.

INTERPRETATION

Long-term exposure to concentrations of PM_2·5 and NO₂ lower than current annual limit values was associated with non-accidental, cardiovascular, non-malignant respiratory, and lung cancer mortality in seven large European cohorts. Continuing research on the effects of low concentrations of air pollutants is expected to further inform the process of setting air quality standards in Europe and other global regions.

FUNDING

Health Effects Institute.

In utero and childhood exposure to tobacco smoke and multi-layer molecular signatures in children

BACKGROUND

The adverse health effects of early life exposure to tobacco smoking have been widely reported. In spite of this, the underlying molecular mechanisms of in utero and postnatal exposure to tobacco smoke are only partially understood. Here, we aimed to identify multi-layer molecular signatures associated with exposure to tobacco smoke in these two exposure windows.

METHODS

We investigated the associations of maternal smoking during pregnancy and childhood secondhand smoke (SHS) exposure with molecular features measured in 1203 European children (mean age 8.1 years) from the Human Early Life Exposome (HELIX) project. Molecular features, covering 4 layers, included blood DNA methylation and gene and miRNA transcription, plasma proteins, and sera and urinary metabolites.

RESULTS

Maternal smoking during pregnancy was associated with DNA methylation changes at 18 loci in child blood. DNA methylation at 5 of these loci was related to expression of the nearby genes. However, the expression of these genes themselves was only weakly associated with maternal smoking. Conversely, childhood SHS was not associated with blood DNA methylation or transcription patterns, but with reduced levels of several serum metabolites and with increased plasma PAI1 (plasminogen activator inhibitor-1), a protein that inhibits fibrinolysis. Some of the in utero and childhood smoking-related molecular marks showed dose-response trends, with stronger effects with higher dose or longer duration of the exposure.

CONCLUSION

In this first study covering multi-layer molecular features, pregnancy and childhood exposure to tobacco smoke were associated with distinct molecular phenotypes in children. The persistent and dose-dependent changes in the methylome make CpGs good candidates to develop biomarkers of past exposure. Moreover, compared to methylation, the weak association of maternal smoking in pregnancy with gene expression suggests different reversal rates and a methylation-based memory to past exposures. Finally, certain metabolites and protein markers evidenced potential early biological effects of postnatal SHS, such as fibrinolysis.

Early-Life Environmental Exposures and Childhood Obesity: An Exposome-Wide Approach

BACKGROUND

Chemical and nonchemical environmental exposures are increasingly suspected to influence the development of obesity, especially during early life, but studies mostly consider single exposure groups.

OBJECTIVES

Our study aimed to systematically assess the association between a wide array of early-life environmental exposures and childhood obesity, using an exposome-wide approach.

METHODS

The HELIX (Human Early Life Exposome) study measured child body mass index (BMI), waist circumference, skinfold thickness, and body fat mass in 1,301 children from six European birth cohorts age 6-11 y. We estimated 77 prenatal exposures and 96 childhood exposures (cross-sectionally), including indoor and outdoor air pollutants, built environment, green spaces, tobacco smoking, and biomarkers of chemical pollutants (persistent organic pollutants, metals, phthalates, phenols, and pesticides). We used an exposure-wide association study (ExWAS) to screen all exposure-outcome associations independently and used the deletion-substitution-addition (DSA) variable selection algorithm to build a final multiexposure model.

RESULTS

The prevalence of overweight and obesity combined was 28.8%. Maternal smoking was the only prenatal exposure variable associated with higher child BMI (z-score increase of 0.28, 95% confidence interval: 0.09, 0.48, for active vs. no smoking). For childhood exposures, the multiexposure model identified particulate and nitrogen dioxide air pollution inside the home, urine cotinine levels indicative of secondhand smoke exposure, and residence in more densely populated areas and in areas with fewer facilities to be associated with increased child BMI. Child blood levels of copper and cesium were associated with higher BMI, and levels of organochlorine pollutants, cobalt, and molybdenum were associated with lower BMI. Similar results were found for the other adiposity outcomes.

DISCUSSION

This first comprehensive and systematic analysis of many suspected environmental obesogens strengthens evidence for an association of smoking, air pollution exposure, and characteristics of the built environment with childhood obesity risk. Cross-sectional biomarker results may suffer from reverse causality bias, whereby obesity status influenced the biomarker concentration. https://doi.org/10.1289/EHP5975.

Low levels of antibodies for the oral bacterium Tannerella forsythia predict cardiovascular disease mortality in men with myocardial infarction: A prospective cohort study

Antibody levels to periodontal pathogens in prediction of cardiovascular disease (CVD) mortality were explored using data from a health survey in Oslo in 2000 (Oslo II-study) with 12 1/2 years follow-up. IgG antibodies to four common periodontal pathogens; Tannerella forsythia (TF), Porphyromonas gingivalis (PG), and Treponema denticola (TD) all termed collectively the "red complex", and Aggregatibacter actinomycetemcomitans(AA) were analysed. The study sample consisted of 1172 men drawn from a cohort of 6,530 men who participated in the Oslo II-study, where they provided information on medical and dental history. Of the study sample, 548 men had reported prior myocardial infarction (MI) at baseline whereas the remaining 624 men were randomly drawn from the ostensibly healthy participants for comparative analyses. Dental anamnestic information included tooth extractions and oral infections. An inverse relation was found for trend by the quartile risk level of TF predicting CVD mortality, p-value for trend = 0.017. Comparison of the first to fourth quartile of TF antibodies resulted in hazard ratio (HR) = 1.82, 95% confidence interval 1.12-2.94, p = 0.015, adjusted for age, education, diabetes, daily smoking, and systolic blood pressure. Specificity comparing decile 1 to deciles 2-10 of TF predicting mortality was 92.3%. We found an increased HR by low levels of antibodies to the bacterium T. forsythia predicting CVD mortality in a 12 ½ years follow-up in persons who had experienced an MI but not among non-MI men. This novel finding constitutes a plausible causal link between oral infections and CVD mortality.

Oral health and cardiovascular disease risk factors and mortality of cerebral haemorrhage, cerebral infarction and unspecified stroke in elderly men: A prospective cohort study

Background: Stroke mortality comprises different specific diagnoses as cerebral infarction, different haemorrhagic conditions and unspecified stroke. This study seeks to explore the prediction of oral health indicators versus known cardiovascular disease risk factors for stroke mortality. Methods: Altogether, 12,764 men aged 58 to 77 years were invited to the health screening Oslo II in the year 2000. It included general medical measurements and questionnaire information. Mortality data were supplied by Statistics Norway for the 6530 attending men. Cox proportional hazards regression analyses were used to establish prediction models for mortality. Results: Oral health by number of tooth extractions >10 was found to be an independent predictor for cerebral infarction hazard ratio = 2.92, 95% confidence interval (1.24-6.89). This was independent of HDL-Cholesterol (inversely) hazard ratio = 0.21, 95% confidence interval (0.06-0.76), frequent alcohol consumption (drinking 4-7 times per week) hazard ratio = 3.58, 95% confidence interval (1.40-9.13) and diabetes hazard ratio = 4.28, 95% confidence interval (1.68-10.89). Predictors for cerebral haemorrhage were age, hs-C-reactive protein and body mass index (inversely). Age and total cholesterol (inversely) were predictors for unspecified stroke. Conclusions: Oral health measured by number of tooth extractions >10 was an independent predictor for cerebral infarction in addition to age, HDL-C, hs-C-reactive protein and diabetes. The pattern of risk factors varied between the specific stroke diagnoses.

Synthetic hydrosilicate nanotubes induce low pro-inflammatory and cytotoxic responses compared to natural chrysotile in lung cell cultures

Asbestos (Mg-hydrosilicate; chrysotile) is known to cause pleural diseases, pulmonary fibrosis and lung cancers, via mechanisms strongly depending on diameter-length ratio and possibly metal content. A critical question is whether synthetic hydrosilicate nanotubes (NTs) of short length possess little toxic potential compared to chrysotile. Five Mg- and two NiNTs of different lengths were assessed for cytotoxicity and pro-inflammatory responses in THP-1 macrophages and human bronchial epithelial lung cells (HBEC3-KT), in comparison with chrysotile. NT lengths/diameters were characterized by TEM, surface areas by BET- and BJH analysis, and chemical composition by XRD. The different Mg- and NiNTs induced little cytotoxicity in both cell models, in contrast to chrysotile that induced marked cytotoxicity. The two longest synthetic MgNTs, with median lengths of 3 and 5 µm, induced increased levels of pro-inflammatory cytokines in THP-1 macrophages, but much less than chrysotile (median length 15 µm) and silica nanoparticles (Si10). The shortest NTs did not induce any increase in cytokines. In HBEC3-KT cells, all synthetic NTs induced no or only small changes in cytokine responses, in contrast to chrysotile and Si10. The synthetic NTs induced lower TGF-β responses than chrysotile in both cell models. In conclusion, the pro-inflammatory responses were associated with the length of synthetic hydrosilicate NTs in THP-1 macrophages, but not in HBEC3-KT cells. Notably, the shortest NTs showed no or little pro-inflammatory activity or cytotoxicity in both cell models. Such a safety by design approach is important for development of new materials being candidates for various new products.

Prenatal and Childhood Traffic-Related Air Pollution Exposure and Telomere Length in European Children: The HELIX Project

BACKGROUND

Telomere length is a molecular marker of biological aging.

OBJECTIVE

Here we investigated whether early-life exposure to residential air pollution was associated with leukocyte telomere length (LTL) at 8 y of age.

METHODS

In a multicenter European birth cohort study, HELIX (Human Early Life Exposome) ([Formula: see text]), we estimated prenatal and 1-y childhood exposure to nitrogen dioxide ([Formula: see text]), particulate matter with aerodynamic diameter [Formula: see text] ([Formula: see text]), and proximity to major roads. Average relative LTL was measured using quantitative real-time polymerase chain reaction (qPCR). Effect estimates of the association between LTL and prenatal, 1-y childhood air pollution, and proximity to major roads were calculated using multiple linear mixed models with a random cohort effect and adjusted for relevant covariates.

RESULTS

LTL was inversely associated with prenatal and 1-y childhood [Formula: see text] and [Formula: see text] exposures levels. Each standard deviation (SD) increase in prenatal [Formula: see text] was associated with a [Formula: see text] (95% CI: [Formula: see text], [Formula: see text]) change in LTL. Prenatal [Formula: see text] was nonsignificantly associated with LTL ([Formula: see text] per SD increase; 95% CI: [Formula: see text], 0.6). For each SD increment in 1-y childhood [Formula: see text] and [Formula: see text] exposure, LTL shortened by [Formula: see text] (95% CI: [Formula: see text], [Formula: see text]) and [Formula: see text] (95% CI: [Formula: see text], 0.1), respectively. Each doubling in residential distance to nearest major road during childhood was associated with a 1.6% (95% CI: 0.02, 3.1) lengthening in LTL.

CONCLUSION

Lower exposures to air pollution during pregnancy and childhood were associated with longer telomeres in European children at 8 y of age. These results suggest that reductions in traffic-related air pollution may promote molecular longevity, as exemplified by telomere length, from early life onward. https://doi.org/10.1289/EHP4148.

Personal assessment of the external exposome during pregnancy and childhood in Europe

The human exposome affects child development and health later in life, but its personal external levels, variability, and correlations are largely unknown. We characterized the personal external exposome of pregnant women and children in eight European cities. Panel studies included 167 pregnant women and 183 children (aged 6-11 years). A personal exposure monitoring kit composed of smartphone, accelerometer, ultraviolet (UV) dosimeter, and two air pollution monitors were used to monitor physical activity (PA), fine particulate matter (PM_2.5), black carbon, traffic-related noise, UV-B radiation, and natural outdoor environments (NOE). 77% of women performed the adult recommendation of ≥150 min/week of moderate to vigorous PA (MVPA), while only 3% of children achieved the childhood recommendation of ≥60 min/day MVPA. 11% of women and 17% of children were exposed to daily PM_2.5 levels higher than recommended (≥25μg/m³). Mean exposure to noise ranged from Lden 51.1 dB in Kaunas to Lden 65.2 dB in Barcelona. 4% of women and 23% of children exceeded the recommended maximum of 2 Standard-Erythemal-Dose of UV-B at least once a week. 33% of women and 43% of children never reached the minimum NOE contact recommendation of ≥30 min/week. The variations in air and noise pollution exposure were dominated by between-city variability, while most of the variation observed for NOE contact and PA was between-participants. The correlations between all personal exposures ranged from very low to low (Rho < 0.30). The levels of personal external exposures in both pregnant women and children are above the health recommendations, and there is little correlation between the different exposures. The assessment of the personal external exposome is feasible but sampling requires from one day to more than one year depending on exposure due to high variability between and within cities and participants.

Influence of the Urban Exposome on Birth Weight

BACKGROUND

The exposome is defined as the totality of environmental exposures from conception onwards. It calls for providing a holistic view of environmental exposures and their effects on human health by evaluating multiple environmental exposures simultaneously during critical periods of life.

OBJECTIVE

We evaluated the association of the urban exposome with birth weight.

METHODS

We estimated exposure to the urban exposome, including the built environment, air pollution, road traffic noise, meteorology, natural space, and road traffic (corresponding to 24 environmental indicators and 60 exposures) for nearly 32,000 pregnant women from six European birth cohorts. To evaluate associations with either continuous birth weight or term low birth weight (TLBW) risk, we primarily relied on the Deletion-Substitution-Addition (DSA) algorithm, which is an extension of the stepwise variable selection method. Second, we used an exposure-by-exposure exposome-wide association studies (ExWAS) method accounting for multiple hypotheses testing to report associations not adjusted for coexposures.

RESULTS

The most consistent statistically significant associations were observed between increasing green space exposure estimated as Normalized Difference Vegetation Index (NDVI) and increased birth weight and decreased TLBW risk. Furthermore, we observed statistically significant associations among presence of public bus line, land use Shannon's Evenness Index, and traffic density and birth weight in our DSA analysis.

CONCLUSION

This investigation is the first large urban exposome study of birth weight that tests many environmental urban exposures. It confirmed previously reported associations for NDVI and generated new hypotheses for a number of built-environment exposures. https://doi.org/10.1289/EHP3971.

Lipophilic components of diesel exhaust particles induce pro-inflammatory responses in human endothelial cells through AhR dependent pathway(s)

Background

Exposure to traffic-derived particulate matter (PM), such as diesel exhaust particles (DEP), is a leading environmental cause of cardiovascular disease (CVD), and may contribute to endothelial dysfunction and development of atherosclerosis. It is still debated how DEP and other inhaled PM can contribute to CVD. However, organic chemicals (OC) adhered to the particle surface, are considered central to many of the biological effects. In the present study, we have explored the ability of OC from DEP to reach the endothelium and trigger pro-inflammatory reactions, a central step on the path to atherosclerosis.

Results

Exposure-relevant concentrations of DEP (0.12 μg/cm²) applied on the epithelial side of an alveolar 3D tri-culture, rapidly induced pro-inflammatory and aryl hydrocarbon receptor (AhR)-regulated genes in the basolateral endothelial cells. These effects seem to be due to soluble lipophilic constituents rather than particle translocation. Extractable organic material of DEP (DEP-EOM) was next fractionated with increasing polarity, chemically characterized, and examined for direct effects on pro-inflammatory and AhR-regulated genes in human microvascular endothelial (HMEC-1) cells and primary human endothelial cells (PHEC) from four healthy donors. Exposure-relevant concentrations of lipophilic DEP-EOM (0.15 μg/cm²) induced low to moderate increases in IL-1α, IL-1β, COX2 and MMP-1 gene expression, and the MMP-1 secretion was increased. By contrast, the more polar EOM had negligible effects, even at higher concentrations. Use of pharmacological inhibitors indicated that AhR and protease-activated receptor-2 (PAR-2) were central in regulation of EOM-induced gene expression. Some effects also seemed to be attributed to redox-responses, at least at the highest exposure concentrations tested. Although the most lipophilic EOM, that contained the majority of PAHs and aliphatics, had the clearest low-concentration effects, there was no straight-forward link between chemical composition and biological effects.

Conclusion

Lipophilic and semi-lipophilic chemicals seemed to detach from DEP, translocate through alveolar epithelial cells and trigger pro-inflammatory reactions in endothelial cells at exposure-relevant concentrations. These effects appeared to be triggered by AhR agonists, and involve PAR-2 signaling.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0257-1) contains supplementary material, which is available to authorized users.

Diagnosis, monitoring and prevention of exposure-related non-communicable diseases in the living and working environment: DiMoPEx-project is designed to determine the impacts of environmental exposure on human health

The WHO has ranked environmental hazardous exposures in the living and working environment among the top risk factors for chronic disease mortality. Worldwide, about 40 million people die each year from noncommunicable diseases (NCDs) including cancer, diabetes, and chronic cardiovascular, neurological and lung diseases. The exposure to ambient pollution in the living and working environment is exacerbated by individual susceptibilities and lifestyle-driven factors to produce complex and complicated NCD etiologies. Research addressing the links between environmental exposure and disease prevalence is key for prevention of the pandemic increase in NCD morbidity and mortality. However, the long latency, the chronic course of some diseases and the necessity to address cumulative exposures over very long periods does mean that it is often difficult to identify causal environmental exposures. EU-funded COST Action DiMoPEx is developing new concepts for a better understanding of health-environment (including gene-environment) interactions in the etiology of NCDs. The overarching idea is to teach and train scientists and physicians to learn how to include efficient and valid exposure assessments in their research and in their clinical practice in current and future cooperative projects. DiMoPEx partners have identified some of the emerging research needs, which include the lack of evidence-based exposure data and the need for human-equivalent animal models mirroring human lifespan and low-dose cumulative exposures. Utilizing an interdisciplinary approach incorporating seven working groups, DiMoPEx will focus on aspects of air pollution with particulate matter including dust and fibers and on exposure to low doses of solvents and sensitizing agents. Biomarkers of early exposure and their associated effects as indicators of disease-derived information will be tested and standardized within individual projects. Risks arising from some NCDs, like pneumoconioses, cancers and allergies, are predictable and preventable. Consequently, preventative action could lead to decreasing disease morbidity and mortality for many of the NCDs that are of major public concern. DiMoPEx plans to catalyze and stimulate interaction of scientists with policy-makers in attacking these exposure-related diseases.

Characterization and pro-inflammatory responses of spore and hyphae samples from various mold species

Mold particles from Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum have been linked to respiratory-related diseases. We characterized X-ray-inactivated spores and hyphae fragments from these species by number of particles, morphology, and mycotoxin, β-glucan and protease content/activity. The pro-inflammatory properties of mold particles were examined in human bronchial epithelial cells (BEAS-2B) and THP-1 monocytes and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. Spores from P. chrysogenum and S. chartarum contained some hyphae fragments, whereas the other preparations contained either spores or hyphae. Each mold species produced mainly one gelatin-degrading protease that was either of the metallo- or serine type, while one remains unclassified. Mycotoxin levels were generally low. Detectable levels of β-glucans were found mainly in hyphae particle preparations. PMA-differentiated THP-1 macrophages were by far the most sensitive model with effects in the order of 10 ng/cm² . Hyphae preparations of A. fumigatus and P. chrysogenum were more potent than respective spore preparations, whereas the opposite seems to be true for A. versicolor and S. chartarum. Hyphae fragments of A. fumigatus, P. chrysogenum, and A. versicolor enhanced the release of metalloprotease (proMMP-9) most markedly. In conclusion, species, growth stage, and characteristics are all important factors for pro-inflammatory potential.

A Population-Based Study on Nighttime Road Traffic Noise and Insomnia

Study Objectives

The aims of the present study were to investigate how nighttime road traffic noise relates to self-reported symptoms of insomnia and sleep medication use.

Methods

We used questionnaire data from the population-based study Health and Environment in Oslo (HELMILO) (2009-2010; n = 13019). The insomnia symptoms difficulties falling asleep, awakenings during the night, and waking up too early in the morning as well as self-reported sleep medication use were included as outcomes. Modeled noise levels (Lnight) were assigned to each participant's home address. For selecting covariates to the statistical model, we used a directed acyclic graph. The associations between noise and sleep were analyzed using logistic regression models.

Results

After adjustment for potential confounders, we found an odds ratio (OR) of 1.05 (95% confidence interval [CI]: 1.01-1.09) for the association between traffic noise and difficulties falling asleep, in the total study population. For the association between traffic noise and awakenings during the night, the OR was 1.04 (95% CI: 1.00-1.08) and for waking up too early, the OR was 1.06 (95% CI: 1.02-1.11). The effect estimates are given per 5-dB increase in traffic noise level (Lnight). Self-reported sleep medication use was not statistically significantly associated with traffic noise exposure.

Conclusions

In an adult population from Oslo, traffic noise was associated with difficulties falling asleep and waking up too early. These findings indicate that sleep quantity may be compromised for individuals living in areas highly exposed to nighttime traffic noise.

Road traffic noise and registry based use of sleep medication

BACKGROUND

Road traffic noise has been associated with adverse health effects including sleep disturbances. Use of sleep medication as an indicator of sleeping problems has rarely been explored in studies of the effects of traffic noise. Furthermore, using registry data on sleep medications provides an opportunity to study the effects of noise on sleep where attribution of sleep problems to noise is not possible.

METHODS

We used questionnaire data from the population-based study Health and Environment in Oslo (HELMILO) (2009-10) (n = 13,019). Individual data on sleep medications was obtained from the Norwegian Prescription Database (NorPD). Noise levels (L _night) were modeled for the most exposed façade of the building at each participant's home address. Logistic regression models adjusted for potential confounders were used to analyze the association between traffic noise and sleep medication use both for one whole year and for the summer season. The results were reported as changes in the effect estimate per 5 decibel (dB) increase in noise level.

RESULTS

We observed no association between traffic noise and sleep medication use during one year [odds ratio (OR) = 1.00; 95% confidence interval (CI): 0.96, 1.04]. For sleep medication use in the summer season, there was a positive, however non-significant association (OR = 1.04; 95% CI: 0.99, 1.10). Among individuals sleeping with the bedroom window open, the association increased slightly and was borderline statistically significant (OR = 1.06; 95% CI: 1.00, 1.12).

CONCLUSIONS

We found no evidence of an association between traffic noise and sleep medication use during one year. However, for the summer season, there was some suggestive evidence of an association. These findings indicate that season may play a role in the association between traffic noise and sleep, possibly because indoor traffic noise levels are likely to be higher during summer due to more frequent window opening. More studies are, however, necessary in order to confirm this.

Nanomaterials Versus Ambient Ultrafine Particles: An Opportunity to Exchange Toxicology Knowledge

BACKGROUND

A rich body of literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), and there is strong support for an important role of ultrafine (nanosized) particles. At present, relatively few human health or epidemiology data exist for engineered nanomaterials (NMs) despite clear parallels in their physicochemical properties and biological actions in in vitro models.

OBJECTIVES

NMs are available with a range of physicochemical characteristics, which allows a more systematic toxicological analysis. Therefore, the study of ultrafine particles (UFP, <100 nm in diameter) provides an opportunity to identify plausible health effects for NMs, and the study of NMs provides an opportunity to facilitate the understanding of the mechanism of toxicity of UFP.

METHODS

A workshop of experts systematically analyzed the available information and identified 19 key lessons that can facilitate knowledge exchange between these discipline areas.

DISCUSSION

Key lessons range from the availability of specific techniques and standard protocols for physicochemical characterization and toxicology assessment to understanding and defining dose and the molecular mechanisms of toxicity. This review identifies a number of key areas in which additional research prioritization would facilitate both research fields simultaneously.

CONCLUSION

There is now an opportunity to apply knowledge from NM toxicology and use it to better inform PM health risk research and vice versa. https://doi.org/10.1289/EHP424.

Triggering Mechanisms and Inflammatory Effects of Combustion Exhaust Particles with Implication for Carcinogenesis

A number of biological responses may contribute to the carcinogenic effects of combustion-derived particulate matter (CPM). Here, we focus on mechanisms that trigger CPM-induced pro-inflammatory responses. Inflammation has both genotoxic and non-genotoxic implications and is considered to play a central role in development of various health outcome associated with CPM exposure, including cancer. Chronic, low-grade inflammation may cause DNA damage through a persistent increased level of reactive oxygen species (ROS) produced and released by activated immune cells. Moreover, a number of pro-inflammatory cytokines and chemokines display mitogenic, motogenic, morphogenic and/or angiogenic properties and may therefore contribute to tumour growth and metastasis. The key triggering events involved in activation of pro-inflammatory responses by CPM and soluble CPM components can be categorized into (i) formation of ROS and oxidative stress, (ii) interaction with the lipid layer of cellular membranes, (iii) activation of receptors, ion channels and transporters on the cell surface and (iv) interactions with intracellular molecular targets including receptors such as the aryl hydrocarbon receptor (AhR). In particular, we will elucidate the effects of diesel exhaust particles (DEP) using human lung epithelial cells as a model system.

Particulate Matter 2.5 Exposure and Self-Reported Use of Wood Stoves and Other Indoor Combustion Sources in Urban Nonsmoking Homes in Norway

Few studies have examined particulate matter (PM) exposure from self-reported use of wood stoves and other indoor combustion sources in urban settings in developed countries. We measured concentrations of indoor PM < 2.5 microns (PM_2.5) for one week with the MicroPEM^™ nephelometer in 36 households in the greater Oslo, Norway metropolitan area. We examined indoor PM_2.5 levels in relation to use of wood stoves and other combustion sources during a 7 day monitoring period using mixed effects linear models with adjustment for ambient PM_2.5 levels. Mean hourly indoor PM_2.5 concentrations were higher (p = 0.04) for the 14 homes with wood stove use (15.6 μg/m³) than for the 22 homes without (12.6 μg/m³). Moreover, mean hourly PM_2.5 was higher (p = 0.001) for use of wood stoves made before 1997 (6 homes, 20.2 μg/m³), when wood stove emission limits were instituted in Norway, compared to newer wood stoves (8 homes, 11.9 μg/m³) which had mean hourly values similar to control homes. Increased PM_2.5 levels during diary-reported burning of candles was detected independently of concomitant wood stove use. These results suggest that self-reported use of wood stoves, particularly older stoves, and other combustion sources, such as candles, are associated with indoor PM_2.5 measurements in an urban population from a high income country.

Air pollution-related metals induce differential cytokine responses in bronchial epithelial cells

Different transition metals have been shown to induce inflammatory responses in lung. We have compared eight different metal ions with regard to cytokine responses, cytotoxicity and signalling mechanisms in a human lung epithelial cell model (BEAS-2B). Among the metal ions tested, there were large differences with respect to pro-inflammatory potential. Exposure to Cd(2+), Zn(2+) and As(3+) induced CXCL8 and IL-6 release at concentrations below 100μM, and Mn(2+) and Ni(2+) at concentrations above 200μM. In contrast, VO4(3-), Cu(2+) and Fe(2+) did not induce any significant increase of these cytokines. An expression array of 20 inflammatory relevant genes also showed a marked up-regulation of CXCL10, IL-10, IL-13 and CSF2 by one or more of the metal ions. The most potent metals, Cd(2+), Zn(2+) and As(3+) induced highest levels of oxidative activity, and ROS appeared to be central in their CXCL8 and IL-6 responses. Activation of the MAPK p38 seemed to be a critical mediator. However, the NF-κB pathway appeared predominately to be involved only in Zn(2+)- and As(3+)-induced CXCL8 and IL-6 responses. Thus, the most potent metals Cd(2+), Zn(2+) and As(3+) seemed to induce a similar pattern for the cytokine responses, and with some exceptions, via similar signalling mechanisms.

Particulate matter properties and health effects: consistency of epidemiological and toxicological studies

Identifying the ambient particulate matter (PM) fractions or constituents, critically involved in eliciting adverse health effects, is crucial to the implementation of more cost-efficient abatement strategies to improve air quality. This review focuses on the importance of different particle properties for PM-induced effects, and whether there is consistency in the results from epidemiological and experimental studies. An evident problem for such comparisons is that epidemiological and experimental data on the effects of specific components of ambient PM are limited. Despite this, some conclusions can be drawn. With respect to the importance of the PM size-fractions, experimental and epidemiological studies are somewhat conflicting, but there seems to be a certain consistency in that the coarse fraction (PM10-2.5) has an effect that should not be neglected. Better exposure characterization may improve the consistency between the results from experimental and epidemiological studies, in particular for ultrafine particles. Experimental data indicate that surface area is an important metric, but composition may play an even greater role in eliciting effects. The consistency between epidemiological and experimental findings for specific PM-components appears most convincing for metals, which seem to be important for the development of both pulmonary and cardiovascular disease. Metals may also be involved in PM-induced allergic sensitization, but the epidemiological evidence for this is scarce. Soluble organic compounds appear to be implicated in PM-induced allergy and cancer, but the data from epidemiological studies are insufficient for any conclusions. The present review suggests that there may be a need for improvements in research designs. In particular, there is a need for better exposure assessments in epidemiological investigations, whereas experimental data would benefit from an improved comparability of studies. Combined experimental and epidemiological investigations may also help answer some of the unresolved issues.

Particulate matter air pollution components and risk for lung cancer

BACKGROUND

Particulate matter (PM) air pollution is a human lung carcinogen; however, the components responsible have not been identified. We assessed the associations between PM components and lung cancer incidence.

METHODS

We used data from 14 cohort studies in eight European countries. We geocoded baseline addresses and assessed air pollution with land-use regression models for eight elements (Cu, Fe, K, Ni, S, Si, V and Zn) in size fractions of PM2.5 and PM10. We used Cox regression models with adjustment for potential confounders for cohort-specific analyses and random effect models for meta-analysis.

RESULTS

The 245,782 cohort members contributed 3,229,220 person-years at risk. During follow-up (mean, 13.1 years), 1878 incident cases of lung cancer were diagnosed. In the meta-analyses, elevated hazard ratios (HRs) for lung cancer were associated with all elements except V; none was statistically significant. In analyses restricted to participants who did not change residence during follow-up, statistically significant associations were found for PM2.5 Cu (HR, 1.25; 95% CI, 1.01-1.53 per 5 ng/m(3)), PM10 Zn (1.28; 1.02-1.59 per 20 ng/m(3)), PM10 S (1.58; 1.03-2.44 per 200 ng/m(3)), PM10 Ni (1.59; 1.12-2.26 per 2 ng/m(3)) and PM10 K (1.17; 1.02-1.33 per 100 ng/m(3)). In two-pollutant models, associations between PM10 and PM2.5 and lung cancer were largely explained by PM2.5 S.

CONCLUSIONS

This study indicates that the association between PM in air pollution and lung cancer can be attributed to various PM components and sources. PM containing S and Ni might be particularly important.

Cytokine responses induced by diesel exhaust particles are suppressed by PAR-2 silencing and antioxidant treatment, and driven by polar and non-polar soluble constituents

Adsorbed soluble organics seem to be the main drivers of inflammatory responses induced by diesel exhaust particles (DEP). The specific compounds contributing to this process and the cellular mechanisms behind DEP-induced inflammation are not well known. We have assessed pro-inflammatory effects of DEP and various soluble DEP fractions, in human bronchial epithelial cells (BEAS-2B). DEP increased the expression of interleukin (IL)-6 and CXCL8. Silencing of the aryl hydrocarbon receptor (AhR) by siRNA or pretreatment with AhR-antagonists did not attenuate DEP-induced IL-6 and CXCL8 responses. However, the halogenated aromatic hydrocarbon (HAH)-selective AhR antagonist CH223191 caused a considerable reduction in DEP-induced CYP1A1 expression indicating that this response may be due to dioxin or dioxin-like constituents in DEP. Knock-down of protease activated receptor (PAR)-2 attenuated IL-6 responses without affecting CXCL8. Antioxidants did not affect IL-6 expression after 4h DEP-exposure and only partly reduced CXCL8 expression. However, after 24h exposure antioxidant treatment partly suppressed IL-6 protein release and completely blocked CXCL8 release. Furthermore, a heptane-soluble (non-polar) extract of DEP induced both IL-6 and CXCL8 release, whereas a PBS-soluble (highly polar) extract induced only IL-6. Thus, pro-inflammatory responses in DEP-exposed epithelial cells appear to be the result of both reactive oxygen species and receptor signaling, mediated through combinatorial effects between both non-polar and polar constituents adhered to the particle surface.

Activation of Proinflammatory Responses in Cells of the Airway Mucosa by Particulate Matter: Oxidant- and Non-Oxidant-Mediated Triggering Mechanisms

Inflammation is considered to play a central role in a diverse range of disease outcomes associated with exposure to various types of inhalable particulates. The initial mechanisms through which particles trigger cellular responses leading to activation of inflammatory responses are crucial to clarify in order to understand what physico-chemical characteristics govern the inflammogenic activity of particulate matter and why some particles are more harmful than others. Recent research suggests that molecular triggering mechanisms involved in activation of proinflammatory genes and onset of inflammatory reactions by particles or soluble particle components can be categorized into direct formation of reactive oxygen species (ROS) with subsequent oxidative stress, interaction with the lipid layer of cellular membranes, activation of cell surface receptors, and direct interactions with intracellular molecular targets. The present review focuses on the immediate effects and responses in cells exposed to particles and central down-stream signaling mechanisms involved in regulation of proinflammatory genes, with special emphasis on the role of oxidant and non-oxidant triggering mechanisms. Importantly, ROS act as a central second-messenger in a variety of signaling pathways. Even non-oxidant mediated triggering mechanisms are therefore also likely to activate downstream redox-regulated events.

Natural-cause mortality and long-term exposure to particle components: an analysis of 19 European cohorts within the multi-center ESCAPE project

BACKGROUND

Studies have shown associations between mortality and long-term exposure to particulate matter air pollution. Few cohort studies have estimated the effects of the elemental composition of particulate matter on mortality.

OBJECTIVES

Our aim was to study the association between natural-cause mortality and long-term exposure to elemental components of particulate matter.

METHODS

Mortality and confounder data from 19 European cohort studies were used. Residential exposure to eight a priori-selected components of particulate matter (PM) was characterized following a strictly standardized protocol. Annual average concentrations of copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc within PM size fractions ≤ 2.5 μm (PM2.5) and ≤ 10 μm (PM10) were estimated using land-use regression models. Cohort-specific statistical analyses of the associations between mortality and air pollution were conducted using Cox proportional hazards models using a common protocol followed by meta-analysis.

RESULTS

The total study population consisted of 291,816 participants, of whom 25,466 died from a natural cause during follow-up (average time of follow-up, 14.3 years). Hazard ratios were positive for almost all elements and statistically significant for PM2.5 sulfur (1.14; 95% CI: 1.06, 1.23 per 200 ng/m3). In a two-pollutant model, the association with PM2.5 sulfur was robust to adjustment for PM2.5 mass, whereas the association with PM2.5 mass was reduced.

CONCLUSIONS

Long-term exposure to PM2.5 sulfur was associated with natural-cause mortality. This association was robust to adjustment for other pollutants and PM2.5.

Differential NF-κB and MAPK activation underlies fluoride- and TPA-mediated CXCL8 (IL-8) induction in lung epithelial cells

Different toxic agents have a varying potential to induce the production of the proinflammatory chemokine, CXCL8 (interleukin [IL]-8), in lung cells. A critical question is which mechanisms determine the magnitude and persistence of the CXCL8 responses to different stimuli. To approach this, we compared the potential of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), and sodium fluoride (NaF) to induce CXCL8 responses in A549 cells, with emphasis on the importance of nuclear factor kappa B (NF-κB)- and mitogen-activated protein kinase (MAPK) signaling. Notably, TPA induced a greater release of CXCL8 than did NaF. Furthermore, TPA induced a strong, rapid, but transient upregulation of CXCL8 messenger (m)RNA, whereas NaF induced a weaker, more delayed, but persistent upregulation. With respect to signaling, TPA led to an early, strong, and relatively transient extracellular signal-regulated kinase (ERK)1/2 phosphorylation, and a less marked and even more transient phosphorylation of c-jun-N-terminal kinases (JNK1/2) and p38. In contrast, NaF elicited a lower, but relatively sustained increase in phosphorylation of ERK1/2, and a marked phosphorylation of p38 and JNK1/2, with the JNK1/2 response as most transient. Only ERK1/2 inhibition affected the TPA response, whereas inhibition of all the three MAPK cascades reduced NaF-induced CXCL8 release. TPA also induced an early, marked phosphorylation/translocation of p65 (NF-κB), whereas NaF induced slower, less pronounced effects on p65. The CXCL8 responses by TPA and NaF were reduced by p65-siRNA. In conclusion, all MAPK cascades were involved in NaF-induced CXCL8 release, whereas only ERK1/2 activation was involved in response to TPA. Furthermore, NF-κB activation appeared to be indispensable for CXCL8 induction. The early response, magnitude, and persistency of MAPK and NF-κB signaling seemed to be critical determinants for the potential to induce CXCL8. These findings underscore that a strong, rapid, and relatively transient activation of ERK1/2 in combination with NF-kB may be sufficient for a strong induction of CXCL8, which may exceed the effects of a more moderate ERK1/2 activation in combination with activation of p38, JNK1/2, and NF-κB.

Arterial blood pressure and long-term exposure to traffic-related air pollution: an analysis in the European Study of Cohorts for Air Pollution Effects (ESCAPE)

BACKGROUND

Long-term exposure to air pollution has been hypothesized to elevate arterial blood pressure (BP). The existing evidence is scarce and country specific.

OBJECTIVES

We investigated the cross-sectional association of long-term traffic-related air pollution with BP and prevalent hypertension in European populations.

METHODS

We analyzed 15 population-based cohorts, participating in the European Study of Cohorts for Air Pollution Effects (ESCAPE). We modeled residential exposure to particulate matter and nitrogen oxides with land use regression using a uniform protocol. We assessed traffic exposure with traffic indicator variables. We analyzed systolic and diastolic BP in participants medicated and nonmedicated with BP-lowering medication (BPLM) separately, adjusting for personal and area-level risk factors and environmental noise. Prevalent hypertension was defined as ≥ 140 mmHg systolic BP, or ≥ 90 mmHg diastolic BP, or intake of BPLM. We combined cohort-specific results using random-effects meta-analysis.

RESULTS

In the main meta-analysis of 113,926 participants, traffic load on major roads within 100 m of the residence was associated with increased systolic and diastolic BP in nonmedicated participants [0.35 mmHg (95% CI: 0.02, 0.68) and 0.22 mmHg (95% CI: 0.04, 0.40) per 4,000,000 vehicles × m/day, respectively]. The estimated odds ratio (OR) for prevalent hypertension was 1.05 (95% CI: 0.99, 1.11) per 4,000,000 vehicles × m/day. Modeled air pollutants and BP were not clearly associated.

CONCLUSIONS

In this first comprehensive meta-analysis of European population-based cohorts, we observed a weak positive association of high residential traffic exposure with BP in nonmedicated participants, and an elevated OR for prevalent hypertension. The relationship of modeled air pollutants with BP was inconsistent.

Mechanisms linked to differences in the mutagenic potential of 1,3-dinitropyrene and 1,8-dinitropyrene

This study explores and characterizes the toxicity of two closely related carcinogenic dinitro-pyrenes (DNPs), 1,3-DNP and 1,8-DNP, in human bronchial epithelial BEAS-2B cells and mouse hepatoma Hepa1c1c7 cells. Neither 1,3-DNP nor 1,8-DNP (3–30 μM) induced cell death in BEAS-2B cells. In Hepa1c1c7 cells only 1,3-DNP (10–30 μM) induced a mixture of apoptotic and necrotic cell death after 24 h. Both compounds increased the level of reactive oxygen species (ROS) in BEAS-2B as measured by CM-H₂DCFDA-fluorescence. A corresponding increase in oxidative damage to DNA was revealed by the formamidopyrimidine-DNA glycosylase (fpg)-modified comet assay. Without fpg, DNP-induced DNA damage detected by the comet assay was only found in Hepa1c1c7 cells. Only 1,8-DNP formed DNA adduct measured by ³²P-postlabelling. In Hepa1c1c cells, 1,8-DNP induced phosphorylation of H2AX (γH2AX) and p53 at a lower concentration than 1,3-DNP and there was no direct correlation between DNA damage/DNA damage response (DR) and induced cytotoxicity. On the other hand, 1,3-DNP-induced apoptosis was inhibited by pifithrin-α, an inhibitor of p53 transcriptional activity. Furthermore, 1,3-DNP triggered an unfolded protein response (UPR), as measured by an increased expression of CHOP, ATF4 and XBP1. Thus, other types of damage possibly linked to endoplasmic reticulum (ER)-stress and/or UPR could be involved in the induced apoptosis. Our results suggest that the stronger carcinogenic potency of 1,8-DNP compared to 1,3-DNP is linked to its higher genotoxic effects. This in combination with its lower potency to induce cell death may increase the probability of causing mutations.

The human early-life exposome (HELIX): project rationale and design

BACKGROUND

Developmental periods in early life may be particularly vulnerable to impacts of environmental exposures. Human research on this topic has generally focused on single exposure-health effect relationships. The "exposome" concept encompasses the totality of exposures from conception onward, complementing the genome.

OBJECTIVES

The Human Early-Life Exposome (HELIX) project is a new collaborative research project that aims to implement novel exposure assessment and biomarker methods to characterize early-life exposure to multiple environmental factors and associate these with omics biomarkers and child health outcomes, thus characterizing the "early-life exposome." Here we describe the general design of the project.

METHODS

In six existing birth cohort studies in Europe, HELIX will estimate prenatal and postnatal exposure to a broad range of chemical and physical exposures. Exposure models will be developed for the full cohorts totaling 32,000 mother-child pairs, and biomarkers will be measured in a subset of 1,200 mother-child pairs. Nested repeat-sampling panel studies (n = 150) will collect data on biomarker variability, use smartphones to assess mobility and physical activity, and perform personal exposure monitoring. Omics techniques will determine molecular profiles (metabolome, proteome, transcriptome, epigenome) associated with exposures. Statistical methods for multiple exposures will provide exposure-response estimates for fetal and child growth, obesity, neurodevelopment, and respiratory outcomes. A health impact assessment exercise will evaluate risks and benefits of combined exposures.

CONCLUSIONS

HELIX is one of the first attempts to describe the early-life exposome of European populations and unravel its relation to omics markers and health in childhood. As proof of concept, it will form an important first step toward the life-course exposome.

Air pollution and nonmalignant respiratory mortality in 16 cohorts within the ESCAPE project

RATIONALE

Prospective cohort studies have shown that chronic exposure to particulate matter and traffic-related air pollution is associated with reduced survival. However, the effects on nonmalignant respiratory mortality are less studied, and the data reported are less consistent.

OBJECTIVES

We have investigated the relationship of long-term exposure to air pollution and nonmalignant respiratory mortality in 16 cohorts with individual level data within the multicenter European Study of Cohorts for Air Pollution Effects (ESCAPE).

METHODS

Data from 16 ongoing cohort studies from Europe were used. The total number of subjects was 307,553. There were 1,559 respiratory deaths during follow-up.

MEASUREMENTS AND MAIN RESULTS

Air pollution exposure was estimated by land use regression models at the baseline residential addresses of study participants and traffic-proximity variables were derived from geographical databases following a standardized procedure within the ESCAPE study. Cohort-specific hazard ratios obtained by Cox proportional hazard models from standardized individual cohort analyses were combined using metaanalyses. We found no significant associations between air pollution exposure and nonmalignant respiratory mortality. Most hazard ratios were slightly below unity, with the exception of the traffic-proximity indicators.

CONCLUSIONS

In this study of 16 cohorts, there was no association between air pollution exposure and nonmalignant respiratory mortality.

Air pollution and lung cancer incidence in 17 European cohorts: prospective analyses from the European Study of Cohorts for Air Pollution Effects (ESCAPE)

BACKGROUND

Ambient air pollution is suspected to cause lung cancer. We aimed to assess the association between long-term exposure to ambient air pollution and lung cancer incidence in European populations.

METHODS

This prospective analysis of data obtained by the European Study of Cohorts for Air Pollution Effects used data from 17 cohort studies based in nine European countries. Baseline addresses were geocoded and we assessed air pollution by land-use regression models for particulate matter (PM) with diameter of less than 10 μm (PM10), less than 2·5 μm (PM2·5), and between 2·5 and 10 μm (PMcoarse), soot (PM2·5absorbance), nitrogen oxides, and two traffic indicators. We used Cox regression models with adjustment for potential confounders for cohort-specific analyses and random effects models for meta-analyses.

FINDINGS

The 312 944 cohort members contributed 4 013 131 person-years at risk. During follow-up (mean 12·8 years), 2095 incident lung cancer cases were diagnosed. The meta-analyses showed a statistically significant association between risk for lung cancer and PM10 (hazard ratio [HR] 1·22 [95% CI 1·03-1·45] per 10 μg/m(3)). For PM2·5 the HR was 1·18 (0·96-1·46) per 5 μg/m(3). The same increments of PM10 and PM2·5 were associated with HRs for adenocarcinomas of the lung of 1·51 (1·10-2·08) and 1·55 (1·05-2·29), respectively. An increase in road traffic of 4000 vehicle-km per day within 100 m of the residence was associated with an HR for lung cancer of 1·09 (0·99-1·21). The results showed no association between lung cancer and nitrogen oxides concentration (HR 1·01 [0·95-1·07] per 20 μg/m(3)) or traffic intensity on the nearest street (HR 1·00 [0·97-1·04] per 5000 vehicles per day).

INTERPRETATION

Particulate matter air pollution contributes to lung cancer incidence in Europe.

FUNDING

European Community's Seventh Framework Programme.

Differential chemokine induction by 1-nitropyrene and 1-aminopyrene in bronchial epithelial cells: importance of the TACE/TGF-α/EGFR-pathway

1-nitropyrene (1-NP), a common PAH in diesel exhaust, and its amine metabolite 1-aminopyrene (1-AP) induce distinctly different chemokine-responses in bronchial epithelial cells (BEAS-2B) characterized by increases in CXCL8 and CCL5, respectively. Tumor necrosis factor-α converting enzyme (TACE), which cleaves membrane-bound transforming growth factor (TGF)-α, activating the epidermal growth factor receptor (EGFR), may regulate pro-inflammatory responses induced by a variety of endogenous and exogenous agents. The present results suggest that CXCL8, but not CCL5 responses in 1-NP- or 1-AP-exposed cells required TACE/TGF-α/EGFR-signaling. The findings strengthen the notion that TACE/TGF-α/EGFR-signaling is central in epithelial CXCL8-regulation upon exposure to multiple airborne pollutants.

Mechanisms of chemokine responses by polycyclic aromatic hydrocarbons in bronchial epithelial cells: sensitization through toll-like receptor-3 priming

We have previously observed that 1-nitropyrene (1-NP) and its amine metabolite 1-aminopyrene (1-AP) induce differential chemokine responses in human bronchial epithelial cells (BEAS-2B) characterized by maximum responses for CXCL8 (IL-8) and CCL5 (RANTES), respectively. In the present study, we further explored the effects of 1-NP and 1-AP on chemokine responses. The results suggest that the differential effect of 1-NP and 1-AP on CXCL8 and CCL5 in BEAS-2B cells was mainly related to effects at higher concentrations, which in the case of 1-NP seemed to be linked to ROS-formation and/or metabolic activation by CYP-enzymes. However, at a low concentration (1 μM) where neither 1-NP, 1-AP nor unsubstituted pyrene had any effect on chemokine responses, we found that all three PAHs potentiated CXCL8 and CCL5 responses induced by the TLR3 ligand polyinosinic:polycytidylic acid (Poly I:C) in BEAS-2B cells. As neither benzo[a]pyrene nor β-naphthoflavone induced a similar effect in Poly I:C-primed cells, the response seemed independent of aryl hydrocarbon receptor-mediated mechanisms. The results show that priming cells with an inflammogenic stimuli like Poly I:C sensitizes the cells toward additional pro-inflammatory effects of certain PAHs. The study underscores that testing on healthy cells or animals may not be sufficient to fully evaluate chemokine responses and the pro-inflammatory potential of organic chemicals.

Wood smoke particles from different combustion phases induce similar pro-inflammatory effects in a co-culture of monocyte and pneumocyte cell lines

BACKGROUND

Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles' physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures.

RESULTS

WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved.

CONCLUSION

The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs.

Wood smoke particles from different combustion phases induce similar pro-inflammatory effects in a co-culture of monocyte and pneumocyte cell lines

BACKGROUND

Exposure to particulate matter (PM) has been linked to several adverse cardiopulmonary effects, probably via biological mechanisms involving inflammation. The pro-inflammatory potential of PM depends on the particles' physical and chemical characteristics, which again depend on the emitting source. Wood combustion is a major source of ambient air pollution in Northern countries during the winter season. The overall aim of this study was therefore to investigate cellular responses to wood smoke particles (WSPs) collected from different phases of the combustion cycle, and from combustion at different temperatures.

RESULTS

WSPs from different phases of the combustion cycle induced very similar effects on pro-inflammatory mediator release, cytotoxicity and cell number, whereas WSPs from medium-temperature combustion were more cytotoxic than WSPs from high-temperature incomplete combustion. Furthermore, comparisons of effects induced by native WSPs with the corresponding organic extracts and washed particles revealed that the organic fraction was the most important determinant for the WSP-induced effects. However, the responses induced by the organic fraction could generally not be linked to the content of the measured polycyclic aromatic hydrocarbons (PAHs), suggesting that also other organic compounds were involved.

CONCLUSION

The toxicity of WSPs seems to a large extent to be determined by stove type and combustion conditions, rather than the phase of the combustion cycle. Notably, this toxicity seems to strongly depend on the organic fraction, and it is probably associated with organic components other than the commonly measured unsubstituted PAHs.

Comparison of non-crystalline silica nanoparticles in IL-1β release from macrophages

BACKGROUND

Respirable crystalline silica (silicon dioxide; SiO₂, quartz) particles are known to induce chronic inflammation and lung disease upon long-term inhalation, whereas non-crystalline (amorphous) SiO₂ particles in the submicrometre range are regarded as less harmful. Several reports have demonstrated that crystalline, but also non-crystalline silica particles induce IL-1β release from macrophages via the NALP3-inflammasome complex (caspase-1, ASC and NALP3) in the presence of lipopolysaccharide (LPS) from bacteria. Our aim was to study the potential of different non-crystalline SiO₂ particles from the nano- to submicro-sized range to activate IL-1β responses in LPS-primed RAW264.7 macrophages and primary rat lung macrophages. The role of the NALP3-inflammasome and up-stream mechanisms was further explored in RAW264.7 cells.

RESULTS

In the present study, we have shown that 6 h exposure to non-crystalline SiO₂ particles in nano- (SiNPs, 5-20 nm, 50 nm) and submicro-sizes induced strong IL-1β responses in LPS-primed mouse macrophages (RAW264.7) and primary rat lung macrophages. The primary lung macrophages were more sensitive to Si-exposure than the RAW-macrophages, and responded more strongly. In the lung macrophages, crystalline silica (MinUsil 5) induced IL-1β release more potently than the non-crystalline Si50 and Si500, when adjusted to surface area. This difference was much less pronounced versus fumed SiNPs. The caspase-1 inhibitor zYVAD and RNA silencing of the NALP3 receptor reduced the particle-induced IL-1β release in the RAW264.7 macrophages. Furthermore, inhibitors of phagocytosis, endosomal acidification, and cathepsin B activity reduced the IL-1β responses to the different particles to a similar extent.

CONCLUSIONS

In conclusion, non-crystalline silica particles in the nano- and submicro-size ranges seemed to induce IL-1β release from LPS-primed RAW264.7 macrophages via similar mechanisms as crystalline silica, involving particle uptake, phagosomal leakage and activation of the NALP3 inflammasome. Notably, rat primary lung macrophages were more sensitive with respect to silica-induced IL-1β release. The differential response patterns obtained suggest that silica-induced IL-1β responses not only depend on the particle surface area, but on factors and/or mechanisms such as particle reactivity or particle uptake. These findings may suggest that bacterial infection via LPS may augment acute inflammatory effects of non-crystalline as well as crystalline silica particles.

Pulmonary and cardiovascular effects of traffic-related particulate matter: 4-week exposure of rats to roadside and diesel engine exhaust particles

Traffic-related particulate matter (PM) may play an important role in the development of adverse health effects, as documented extensively in acute toxicity studies. However, rather little is known about the impacts of prolonged exposure to PM. We hypothesized that long-term exposure to PM from traffic adversely affects the pulmonary and cardiovascular system through exacerbation of an inflammatory response. To examine this hypothesis, Fisher F344 rats, with a mild pulmonary inflammation at the onset of exposure, were exposed for 4 weeks, 5 days/week for 6 h a day to: (a) diluted diesel engine exhaust (PM(DEE)), or: (b) near roadside PM (PM(2.5)). Ultrafine particulates, which are largely present in diesel soot, may enter the systemic circulation and directly or indirectly trigger cardiovascular effects. Hence, we assessed the effects of traffic-related PM on pulmonary inflammation and activity of procoagulants, vascular function in arteries, and cytokine levels in the heart 24 h after termination of the exposures. No major adverse health effects of prolonged exposure to traffic-related PM were detected. However, some systemic effects due to PM(DEE) exposure occurred including decreased numbers of white blood cells and reduced von Willebrand factor protein in the circulation. In addition, lung tissue factor activity is reduced in conjunction with reduced lung tissue thrombin generation. To what extent these alterations contribute to thrombotic effects and vascular diseases remains to be established. In conclusion, prolonged exposure to traffic-related PM in healthy animals may not be detrimental due to various biological adaptive response mechanisms.

Mono(2-ethylhexyl) phthalate induces both pro- and anti-inflammatory responses in rat alveolar macrophages through crosstalk between p38, the lipoxygenase pathway and PPARalpha

Airway inflammation is important in asthma pathogenesis. Recent epidemiological data have indicated an association between asthma symptoms in children and exposure to di(2-ethylhexyl) phthalate (DEHP). Thus, we have studied inflammatory responses in primary rat alveolar macrophages (AMs) after exposure to mono(2-ethylhexyl) phthalate (MEHP), the major primary metabolite of DEHP. First, we show that MEHP induces a dose-dependent release of the pro-inflammatory tumour necrosis factor-alpha (TNF-alpha) in AMs, giving a maximal (5-fold) increase at 0.7 mM. This concentration also induced some cell death. MEHP also induced phosphorylation of MAPK p38, while the p38 inhibitor SB 202190 reduced MEHP-induced TNF-alpha, suggesting a p38-dependent cytokine production. Next, we elucidated possible effects of MEHP on the 5-lipoxygenase (5-LO) pathway and found that MEHP caused increased leukotriene (LTB(4)) release. Further, we found that the 5-LO inhibitor nordihydrogualaretic acid (NDGA) significantly reduced both MEHP-induced TNF-alpha release and MEHP-induced formation of reactive oxygen species (ROS), supporting an involvement of the 5-LO pathway in MEHP induced inflammatory reactions. Last, we found that MK-886, a known inhibitor of peroxisome proliferator-activated receptor alpha (PPARalpha), increased the MEHP-induced TNF-alpha response. This indicates that MEPH-PPARalpha binding mediates an anti-inflammatory signal.

Health effects of residential wood smoke particles: the importance of combustion conditions and physicochemical particle properties

BACKGROUND

Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles.

OUTLINE

The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties.

CONCLUSION

Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.

Helseeffekter av byluftpartikler

Svevestøv i byluft består av forbrenningspartikler og mineralpartikler med svært forskjellige størrelser og kjemiske egenskaper. Svevestøvet kan deles inn i størrelsesfraksjoner som PMAmbient particulate matter (PM) comprises particles from different combustion processes and a variety of mineral particles. The particles vary widely in size distribution and chemical/physical characteristics. PM is often divided into size fractions with different aerodynamic diameters: PM10 (PM ! 10 mm), PM2.5 (PM ! 2.5 mm) and PM0.1 (PM ! 0.1 mm). Recent population studies have found an association between an increase in mortality and morbidity due to lung and/or cardiovascular disease and short-term increases in PM. The relative risk (RR) was approximately 1.005 for an increase in 10 mg/m3 PM10, without an observed threshold even at concentrations below 10 mg/m3. Chronic exposure has been investigated to a lesser extent, but longterm exposure to PM2.5 has been found to be associated with an approximately 10-fold greater increase in RR than short-term exposures. Experimental studies with volunteers in chamber and field studies show mild lung or cardiovascular responses at concentrations of ambient particles (PM2.5/PM10: 100-200 mg/m3) that may occur during episodes of air pollution. Animal studies at higher concentrations have shown stronger responses. The experimental studies support the epidemiological evidence for an adverse health effect of PM. Both population- and experimental studies indicate the existence of vulnerable individuals. At low to average ambient concentrations there seems to exist a discrepancy between the results of population- and experimental studies that might be due to the absence of the most vulnerable individuals in the experimental studies. Together with cell culture experiments, human and animal studies indicate the importance of physical and chemical properties of the particles (size, content of metals, organics, endotoxins, etc.) for the observed effects. More knowledge about adverse health effects induced by low concentrations of PM and the critical particle characteristics, is required.10 (PM £ 10 mm), PM2,5 (PM £ 2,5 mm) og PM0,1 (PM £ 0,1 mm). Nyere befolkningsstudier viser en assosiasjon mellom økning i dødelighet og sykelighet (pga. lunge- og hjertekarsykdommer) og kortvarige økninger i svevestøvskonsentrasjoner i byluft. Den relative risikoen (RR) er rundt 1,005 ved en økning av PM10 på 10 mg/m3, uten noen observert terskelverdi, selv ved nivåer under 10 mg/m3. Kronisk eksponering for svevestøv er mindre undersøkt, men årelang eksponering for PM2,5 er assosiert med en RR som er omlag 10 ganger større enn ved korttidseksponering. Befolkningsstudiene indikerer at enkelte grupper synes å være spesielt følsomme (lungesyke, hjertesyke og barn). Hos frivillige individer i kammer- og feltstudier, fant man effekter både i luftveiene og i hjerte-karsystemet ved konsentrasjoner av svevestøv (PM2,5/PM10: 100-200 mg/m3) som kan forekomme i episoder med økt luftforurensning. Dyreforsøk med høyere konsentrasjoner ga kraftigere responser. De eksperimentelle studiene understøtter befolkningsstudiene i at byluftpartikler representerer et helseproblem. Både befolkningsstudiene og eksperimentelle studier indikerer at enkelte individer er mer sårbare enn andre. Ved lave til middels konsentrasjoner av byluftpartikler synes det å foreligge en diskrepans mellom disse studietypene som kan skyldes at de mest sårbare individene ikke er inkludert i eksperimentelle forsøk. Studier med mennesker, dyr og celler viser at fysisk/kjemiske egenskaper ved partiklene (størrelse, innhold av metaller, organiske forbindelser, endotoksiner etc.) er sentrale for de observerte effektene av svevestøvet. Mer kunnskap både om helseeffekter ved lave konsentrasjoner, samt egenskaper ved partikler, er nødvendig.

Differences in cytotoxicity versus pro-inflammatory potency of different PM fractions in human epithelial lung cells

Air pollution in Milan causes health concern due to the high concentrations of particulate matter (PM10 and PM2.5). The aim of this study was to investigate possible seasonal differences in PM10 and PM2.5 chemical composition and their biological effects on pro-inflammatory cytokine release and cytotoxicity. The PM was sampled during winter and summer seasons. The winter PMs had higher levels of PAHs than the summer samples which contained a greater amount of mineral dust elements. The PM toxicity was tested in the human pulmonary epithelial cell lines BEAS-2B and A549. The winter PMs were more cytotoxic than summer samples, whereas the summer PM10 exhibited a higher pro-inflammatory potential, as measured by ELISA. This inflammatory potential seemed partly due to biological components such as bacterial lipopolysaccharides (LPS), as evaluated by the use of Polymixin B. Interestingly, in the BEAS-2B cells the winter PM2.5 reduced proliferation due to a mitotic delay/arrest, while no such effects were observed in the A549 cells. These results underline that the in vitro responsiveness to PM may be cell line dependent and suggest that the PM different properties may trigger different endpoints such as inflammation, perturbation of cell cycle and cell death.

IL-1beta differently involved in IL-8 and FGF-2 release in crystalline silica-treated lung cell co-cultures

Background

Inhalation of crystalline silica particles is in humans associated with inflammation and development of fibrosis. The aim of the present study was to investigate the effect of crystalline silica on the release of the fibrosis- and angiogenesis-related mediator FGF-2 and the pro-inflammatory mediator IL-8, and how IL-1β and TNF-α were involved in this release from various mono- and co-cultures of monocytes, pneumocytes and endothelial cells.

Results

Silica exposure induced an increase of IL-8 release from monocytes and from pneumocytes alone, and the FGF-2 level in the medium increased upon silica exposure of pneumocytes. Both the responses were enhanced in non-contact co-cultures with endothelial cells. The FGF-2 release seemed to increase with the silica-induced decrease in the number of pneumocytes. The release of IL-8 and FGF-2 was partially suppressed in cultures with pneumocytes in contact with monocytes compared to non-contact cultures. Treatment with anti-TNF-α and the IL-1 receptor antagonist revealed that release of IL-1β, and not TNF-α, from monocytes dominated the regulation of IL-8 release in co-cultures. For release of FGF-2, IL-1ra was without effect. However, exogenous IL-1β reduced the FGF-2 levels, strongly elevated the FGF-2-binding protein PTX3, and prevented the reduction in the number of pneumocytes induced by silica.

Conclusion

IL-1β seems to be differently involved in the silica-induced release of IL-8 and FGF-2 in different lung cell cultures. Whereas the silica-induced IL-8 release is regulated via an IL-1-receptor-mediated mechanism, IL-1β is suggested only indirectly to affect the silica-induced FGF-2 release by counteracting pneumocyte loss. Furthermore, the enhanced IL-8 and FGF-2 responses in co-cultures involving endothelial cells show the importance of the interaction between different cell types and may suggest that both these mediators are important in angiogenic or fibrogenic processes.

Associations between environmental exposures and serum concentrations of Clara cell protein among elderly men in Oslo, Norway

Cardiopulmonary morbidity and mortality is associated with several environmental exposures. Mechanistically, pathophysiological changes in the cardiopulmonary system may lead to the induction of inflammatory responses. In the present study we explored associations between environmental exposures and serum concentrations of lung Clara cell protein 16kDa, a biomarker that has recently been used to assess the integrity of the lung epithelium. Serum Clara cell protein concentrations were associated with both number of cigarettes smoked per day and number of pack-years of smoking. There was no evidence of an association between long-term exposure to ambient air pollution, as assessed at each participant's home address, and serum concentrations of CC16. However, short-term variations in both ambient air pollution and temperature were associated with increases in serum Clara cell concentrations. All findings were robust when other factors were adjusted for. These findings suggest that acute environmental exposures may compromise the integrity of the lung epithelium and lead to increased epithelial barrier permeability in the lungs of elderly men.

Importance of Size and Composition of Particles for Effects on Cells In Vitro

A primary goal of current research on particle-induced health effects is to reveal the critical characteristics that determine their biological effects. Experimental studies have shown that smaller particles induce stronger biological effects than larger particles of similar composition, due to their larger surface area to mass ratio. However, correlation for variations in surface area could not account for variation in biological reactivity among particles of differential composition. Hence, the importance of size and surface area does not override the importance of particle composition. Moreover, different particle characteristics appear to be involved in different biological effects in vitro. Our studies show that mineral particle-induced apoptosis mostly seems to depend on particle size, whereas composition and surface reactivity appeared to be most important for the proinflammatory potential of the particles. The ability of the particles to generate reactive oxygen species in vitro was not correlated with either inflammatory markers or apoptosis, suggesting that other mechanisms are at play. A single, specific component of the mineral particles, explaining the differences in response, has not been identified. In European-wide studies such as the Respiratory Allergy and Inflammation due to Air Pollution (RAIAP) study, particles have been sampled in different locations to study season- and site-dependent variations in responses particles, such as markers of inflammatory and allergic reactions in cells and animals. The data indicate that coarse particles can induce at least as strong inflammatory responses as fine particles. The allergic responses tended to be more associated with the organic fraction (PAH) of particles, whereas the inflammatory reactions seemed to be more associated with metals and endotoxin. Overall, coarse PM was found to have an inflammatory potential similar to fine PM on an equal mass basis. Even though one has to take into account different concentrations in ambient air as well as differences in respiratory system deposition of the size fractions, the potential of coarse particles to induce pulmonary effects should not be neglected.