Chemical constituents of fine particulate air pollution and pulmonary function in healthy adults: the Healthy Volunteer Natural Relocation study

Associations of personal PM2.5-bound heavy metals and heavy metal mixture with lung function: Results from a panel study in Chinese urban residents

BACKGROUND

There are a few reports on the associations between fine particulate matter (PM2.5)-bound heavy metals and lung function.

OBJECTIVES

To evaluate the associations of single and mixed PM2.5-bound heavy metals with lung function.

METHODS

This study included 316 observations of 224 Chinese adults from the Wuhan-Zhuhai cohort over two study periods, and measured participants' personal PM2.5-bound heavy metals and lung function. Three linear mixed models, including the single constituent model, the PM2.5-adjusted constituent model, and the constituent residual model were used to evaluate the association between single metal and lung function. Mixed exposure models including Bayesian kernel machine regression (BKMR) model, weighted quantile sum (WQS) model, and Explainable Machine Learning model were used to assess the relationship between PM2.5-bound heavy metal mixtures and lung function.

RESULTS

In the single exposure analyses, significant negative associations of PM2.5-bound lead, antimony, and cadmium with peak expiratory flow (PEF) were observed. In the mixed exposure analyses, significant decreases in forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC), maximal mid-expiratory flow (MMF), and forced expiratory flow at 75% of the pulmonary volume (FEF75) were associated with the increased PM2.5-bound heavy metal mixture. The BKMR models suggested negative associations of PM2.5-bound lead and antimony with lung function. In addition, PM2.5-bound copper was positively associated with FEV1/FVC, MMF, and FEF75. The Explainable Machine Learning models suggested that FEV1/FVC, MMF, and FEF75 decreased with the elevated PM2.5-bound lead, manganese, and vanadium, and increased with the elevated PM2.5-bound copper.

CONCLUSIONS

The negative relationships were detected between PM2.5-bound heavy metal mixture and FEV1/FVC, MMF, as well as FEF75. Among the PM2.5-bound heavy metal mixture, PM2.5-bound lead, antimony, manganese, and vanadium were negatively associated with FEV1/FVC, MMF, and FEF75, while PM2.5-bound copper was positively associated with FEV1/FVC, MMF, and FEF75.

Mechanisms of microbial resistance against cadmium - a review

The escalating cadmium influx from industrial activities and anthropogenic sources has raised serious environmental concerns due to its toxic effects on ecosystems and human health. This review delves into the intricate mechanisms underlying microbial resistance to cadmium, shedding light on the multifaceted interplay between microorganisms and this hazardous heavy metal. Cadmium overexposure elicits severe health repercussions, including renal carcinoma, mucous membrane degradation, bone density loss, and kidney stone formation in humans. Moreover, its deleterious impact extends to animal and plant metabolism. While physico-chemical methods like reverse osmosis and ion exchange are employed to mitigate cadmium contamination, their costliness and incomplete efficacy necessitate alternative strategies. Microbes, particularly bacteria and fungi, exhibit remarkable resilience to elevated cadmium concentrations through intricate resistance mechanisms. This paper elucidates the ingenious strategies employed by these microorganisms to combat cadmium stress, encompassing metal ion sequestration, efflux pumps, and enzymatic detoxification pathways. Bioremediation emerges as a promising avenue for tackling cadmium pollution, leveraging microorganisms' ability to transform toxic cadmium forms into less hazardous derivatives. Unlike conventional methods, bioremediation offers a cost-effective, environmentally benign, and efficient approach. This review amalgamates the current understanding of microbial cadmium resistance mechanisms, highlighting their potential for sustainable remediation strategies. By unraveling the intricate interactions between microorganisms and cadmium, this study contributes to advancing our knowledge of bioremediation approaches, thereby paving the way for safer and more effective cadmium mitigation practices.

Nickel in ambient particulate matter and respiratory or cardiovascular outcomes: A critical review

Exposure to ambient particulate matter (PM) has been associated with respiratory and cardiovascular outcomes, and nickel has been more frequently associated with these outcomes than other metal constituents of ambient PM. Because of this, we evaluated whether the evidence to date supports causal relationships between exposure to nickel in ambient PM and respiratory or cardiovascular outcomes. We critically reviewed 38 studies in human populations published between 2012 and 2022. Although a large variety of respiratory and cardiovascular outcomes were examined, data were sparse for many. As a result, we focused our evaluation on seven respiratory outcomes and three cardiovascular outcomes that were each examined in ≥3 studies. Of these health outcomes, exposure to nickel in ambient PM has been statistically significantly associated with respiratory mortality, respiratory emergency hospital visits, asthma, lung function (i.e., forced expiratory volume in 1 s, forced vital capacity), cardiovascular mortality, and ischemic heart disease mortality. Studies of the health outcomes of focus are subject to multiple methodological limitations, primarily ecological fallacy (short-term exposure studies), exposure measurement error, confounding, model misspecification, and multiple comparisons issue. While some statistically significant associations were reported, they were not strong, precise, or consistent. Statistically significant findings for long-term exposure to nickel in PM were largely reported in studies that could not establish temporality, despite their cohort study design. Statistically significant findings for short-term exposure to nickel in PM were largely reported in studies that could establish temporality, although this cannot inform causal inference at the individual level due to the aggregate level data used. The biological plausibility of the associations is only supported at high concentrations not relevant to ambient exposures. Overall, the literature to date does not provide adequate support for a causal relationship between nickel in ambient PM and respiratory or cardiovascular outcomes.

The incidence of upper respiratory infections in children is related to the concentration of vanadium in indoor dust aggregates

Background

It has been reported that the disease-initiated and disease-mediated effects of aerosol pollutants can be related to concentration, site of deposition, duration of exposure, as well as the specific chemical composition of pollutants.

Objectives

To investigate the microelemental composition of dust aggregates in primary schools of Vilnius and determine trace elements related to acute upper respiratory infections among 6-to 11-year-old children.

Methods

Microelemental analysis of aerosol pollution was performed using dust samples collected in the classrooms of 11 primary schools in Vilnius from 2016 to 2020. Sites included areas of its natural accumulation behind the radiator heaters and from the surface of high cupboards. The concentrations of heavy metals (Pb, W, Sb, Sn, Zr, Zn, Cu, Ni, Mn, Cr, V, and As) in dust samples were analyzed using a SPECTRO XEPOS spectrometer. The annual incidence rates of respiratory diseases in children of each school were calculated based on data from medical records.

Results

The mean annual incidence of physician-diagnosed acute upper respiratory infections (J00-J06 according to ICD-10A) among younger school-age children was between 25.1 and 71.3% per school. A significant correlation was found between vanadium concentration and the number of episodes of acute upper respiratory infections during each study year from 2016 to 2020. The lowest was r = 0.67 (p = 0.024), and the highest was r = 0.82 (p = 0.002). The concentration of vanadium in the samples of dust aggregates varied from 12.7 to 52.1 parts per million (ppm). No significant correlations between the other trace elements and the incidence of upper respiratory infections were found, which could be caused by a small number of study schools and relatively low concentrations of other heavy metals found in the samples of indoor dust aggregates.

Conclusion

A significant and replicable correlation was found between the concentration of vanadium in the samples of natural dust aggregates collected in primary schools and the incidence of acute upper respiratory infections in children. Monitoring the concentration of heavy metals in the indoor environment can be an important instrument for the prevention and control of respiratory morbidity in children.

Higher temperature and humidity exacerbate pollutant-associated lung dysfunction in the elderly

RATIONALE

Air pollution and extreme temperature and humidity are risk factors for lung dysfunction, but their interactions are not clearly understood.

OBJECTIVES

To assess the impact of exposure to air pollutants and meteorological factors on lung function, and the contribution of their interaction to the overall effect.

METHODS

The peak expiratory flow rates of 135 participants were repeatedly measured during up to four visits. Two weeks before each visit, the concentrations of gaseous pollutants and 19 fine particle components, and the temperature and relative humidity, were continuously monitored in the community where they lived. A Bayesian Kernel machine regression model was used to explore the non-linear exposure-response relationships of the peak expiratory flow rate with pollutant exposure and meteorological factors, and their interactions.

MEASUREMENTS AND MAIN RESULTS

Increased temperature and relative humidity could exacerbate pollutant-associated decline in the peak expiratory flow rate, although their associations with lung dysfunction disappeared after adjustment for pollutant exposure. For example, declines of peak expiratory flow rate associated with interquartile range increase of 3-day cadmium exposure were -0.03 and -0.07 units, when temperature was at 0.1 and 19.5 °C, respectively. Decreased temperature were associated with declines of peak expiratory flow rate after adjustment for pollutant exposure, and had interaction with pollutant exposure on lung dysfunction.

CONCLUSIONS

High temperature, low temperature, and high humidity were all high-risk factors for lung dysfunction, and their interactions with pollutant levels contributed greatly to the overall effects.

Short-term effects of the chemical components of fine particulate matter on pulmonary function: A repeated panel study among adolescents

The effects of the chemical components of fine particulate matter (PM2.5) have been drawing attention. However, information regarding the impact of low PM2.5 concentrations is limited. Hence, we aimed to investigate the short-term effects of the chemical components of PM2.5 on pulmonary function and their seasonal differences in healthy adolescents living on an isolated island without major artificial sources of air pollution. A panel study was repeatedly conducted twice a year for one month every spring and fall from October 2014 to November 2016 on an isolated island in the Seto Inland Sea, which has no major artificial sources of air pollution. Daily measurements of peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) were performed in 47 healthy college students, and the concentrations of 35 chemical components of PM2.5 were analyzed every 24 h. Using a mixed-effects model, the relationship between pulmonary function values and concentrations of PM2.5 components was analyzed. Significant associations were observed between several PM2.5 components and decreased pulmonary function. Among the ionic components, sulfate was strongly related to decreases in PEF and FEV1 (-4.20 L/min [95 % confidence interval (CI): -6.40 to -2.00] and - 0.04 L [95 % CI: -0.05 to -0.02] per interquartile range increase, respectively). Among the elemental components, potassium induced the greatest reduction in PEF and FEV1. Therefore, PEF and FEV1 were significantly reduced as the concentrations of several PM2.5 components increased during fall, with minimal changes observed during spring. Several chemical components of PM2.5 were significantly associated with decreased pulmonary function among healthy adolescents. The concentrations of PM2.5 chemical components differed by season, suggesting the occurrence of distinct effects on the respiratory system depending on the type of component.

Achieving health-oriented air pollution control requires integrating unequal toxicities of industrial particles

Protecting human health from fine particulate matter (PM) pollution is the ambitious goal of clean air actions, but current control strategies  largely ignore the role of source-specific PM toxicity. Here, we proposed health-oriented control strategies by integrating the unequal toxic potencies of the most polluting industrial PMs. Iron and steel industry (ISI)-emitted PM2.5 exhibit about one order of magnitude higher toxic potency than those of cement and power industries. Compared with the current mass-based control strategy (prioritizing implementation of ultralow emission standards in the power sector), the proposed health-oriented control strategy (priority control of the ISI sector) could generate 5.4 times higher reduction in population-weighted toxic potency-adjusted PM2.5 exposure among polluting industries in China. Furthermore, the marginal abatement cost per unit of toxic potency-adjusted mass of ISI-emitted PM2.5 is only a quarter of that of the other two sectors under ultralow emission scenarios. We highlight that a health-oriented air pollution control strategy is urgently required to achieve cost-effective reductions in particulate exposure risks.

Lias overexpression alleviates pulmonary injury induced by fine particulate matter in mice

Oxidative stress and inflammation are mechanisms underlying toxicity induced by fine particulate matter (PM2.5). The antioxidant baseline of the human body modulates the intensity of oxidative stress in vivo. This present study aimed to evaluate the role of endogenous antioxidants in alleviating PM2.5-induced pulmonary injury using a novel mouse model (LiasH/H) with an endogenous antioxidant capacity of approximately 150% of its wild-type counterpart (Lias+/+). LiasH/H and wild-type (Lias+/+) mice were randomly divided into control and PM2.5 exposure groups (n = 10), respectively. Mice in the PM2.5 group and the control group were intratracheally instilled with PM2.5 suspension and saline, respectively, once a day for 7 consecutive days. The metal content, major pathological changes in the lung, and levels of oxidative stress and inflammation biomarkers were examined. The results showed that PM2.5 exposure induced oxidative stress in mice. Overexpression of the Lias gene significantly increased the antioxidant levels and decreased inflammatory responses induced by PM2.5. Further study found that LiasH/H mice exerted their antioxidant function by activating the ROS-p38MAPK-Nrf2 pathway. Therefore, the novel mouse model is useful for the elucidation of the mechanisms of pulmonary injury induced by PM2.5.

The effects of metals and mixture exposure on lung function and the potential mediating effects of oxidative stress

Exposure to metals is associated with lung function decline. However, limited data are available about effects of co-exposure of metals on lung function. Additionally, the mechanism of the association between metals and lung function remains unclear. We conducted a longitudinal panel study in 2017-2018 among 45 healthy college students. Urinary 15 metals, lung function, biomarkers of oxidative stress and inflammation of participants were measured. Linear mixed effect (LME) and Bayesian kernel machine regression (BKMR) models were applied to explore the associations of urinary metals and mixture with lung function. Furthermore, we analyzed the mediating effect of biomarkers in the association between urinary metals and lung function. LME models showed the negative associations of aluminum (Al), vanadium (V), manganese (Mn), cobalt (Co), nickel (Ni), cadmium (Cd) or antimony (Sb) with Forced vital capacity (FVC), and V, Co, Ni, and Sb with Forced expiratory volume in one second (FEV1). BKMR models indicated the overall effect of metals mixture was negatively associated with FEV1 and FVC; urinary Sb was identified as the major contributor to decreased FVC and FEV1. Urinary 8-hydroxydeoxyguanosine mediated the association of Al, Mn, or Sb with FVC and the relationship of V with FEV1. The results revealed the longitudinal dose-response relationships of urinary metals with pulmonary function among healthy adults. Oxidative stress may be the underlying mechanisms of metals exposure associated with decreased lung function. Due to the small sample size, the interpretation of the results of this study should be cautious, and more studies are needed to verify the findings of this study.

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants, originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities, undergo complex atmospheric chemical reactions and multiphase processes. Secondary gaseous pollutants represented by ozone and secondary particulate matter, including sulfates, nitrates, ammonium salts, and secondary organic aerosols, are formed in the atmosphere, affecting air quality and human health. This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants. Meanwhile, different secondary pollutants' toxicological effects and corresponding health risks are evaluated. Studies have shown that secondary pollutants are generally more toxic than primary ones. However, due to their diverse source and complex generation mechanism, the study of the toxicological effects of secondary pollutants is still in its early stages. Therefore, this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone's toxicological effects. In terms of particulate matter, secondary inorganic and organic particulate matters are summarized separately, then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed. Finally, secondary pollutants generated in the indoor environment are briefly introduced. Overall, a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Independent and combined associations of multiple-heavy-metal exposure with lung function: a population-based study in US children

Previous research has found relationships between some single metals and lung function parameters. However, the role of simultaneous multi-metal exposure is poorly understood. The crucial period throughout childhood, when people are most susceptible to environmental dangers, has also been largely ignored. The study aimed to evaluate the joint and individual associations of 12 selected urinary metals with pediatric lung function measures using multi-pollutant approaches. A total of 1227 children aged 6-17 years from the National Health and Nutrition Examination Survey database of the 2007-2012 cycles were used. The metal exposure indicators were 12 urine metals adjusted for urine creatinine, including arsenic (As), barium (Ba), cadmium (Cd), cesium (Cs), cobalt (Co), mercury (Hg), molybdenum (Mo), lead (Pb), antimony (Sb), thallium (Tl), tungsten (Tu), and uranium (Ur). The outcomes of interest were lung function indices, including the 1st second of a forceful exhalation (FEV₁), forced vital capacity (FVC), forced expiratory flow between 25 and 7% of vital capacity (FEF_25-75%), and peak expiratory flow (PEF). Multivariate linear regression, quantile g-computation (QG-C), and Bayesian kernel machine regression models (BKMR) were adopted. A significantly negative overall effect of metal mixtures on FEV₁ (β = - 161.70, 95% CI - 218.12, - 105.27; p < 0.001), FVC (β = - 182.69, 95% CI - 246.33, - 119.06; p < 0.001), FEF_25-75% (β = - 178.86 (95% CI - 274.47, - 83.26; p < 0.001), and PEF (β = - 424.17, 95% CI - 556.55, - 291.80; p < 0.001) was observed. Pb had the largest negative contribution to the negative associations, with posterior inclusion probabilities (PIPs) of 1 for FEV₁, FVC, and FEF_25-75%, and 0.9966 for PEF. And Pb's relationship with lung function metrics showed to be nonlinear, with an approximate "L" shape. Potential interactions between Pb and Cd in lung function decline were observed. Ba was positively associated with lung function metrics. Metal mixtures were negatively associated with pediatric lung function. Pb might be a crucial element. Our findings highlight the need for prioritizing children's environmental health to protect them from later respiratory disorders and to guide future research into the toxic mechanisms of metal-mediated lung function injury in the pediatric population.

The causal links between long-term exposure to major PM2.5 components and the burden of tuberculosis in China

BACKGROUND

We aimed to estimate the causal impacts of long-term exposure to major PM_2.5 components - including black carbon, organic matter, sulfate, nitrate, and ammonium - on the incidence and mortality of tuberculosis in China.

METHODS

We collected annual and provincial-level tuberculosis incidence and mortality, concentrations of PM_2.5 components, and socioeconomic indicators from between 2004 and 2018 in mainland China. We used the difference-in-differences (DID) causal inference approach with a generalized weighted quantile sum (gWQS) regression model to estimate the long-term effects and relative contributions of PM_2.5 components' exposure on tuberculosis incidence and mortality.

RESULTS

We found that long-term multi-components exposure was significantly associated with tuberculosis incidence (WQS index IR%:8.34 %, 95 % CI:4.54 %-12.27 %) and mortality (WQS index IR%:19.49 %, 95 % CI: 9.72 %-30.13 %). Primary pollutants, black carbon and organic matter, contributed most of the overall mixture effect (over 85 %). Nitrate showed a critical role in tuberculosis burden in not-aging provinces and in regions at the Q3 stratum (i.e., the 3rd quartile) of GDP per capita and urbanization rate. Meanwhile the contribution of sulfate to tuberculosis burden in regions at the Q1 stratum of GDP per capita and urbanization rate was the largest among the effect of secondary pollutants (i.e., sulfate, nitrate, and ammonium).

CONCLUSION

The mitigation of black carbon and organic matter pollution may significantly reduce the tuberculosis burden in China. Controlling nitrate emissions and increasing clean energy (i.e., energy sources with limited pollution emissions, such as natural gas and clean coal) may also be effective in certain regions.

Unique regulatory roles of ncRNAs changed by PM2.5 in human diseases

PM_2.5 is a type of particulate matter with an aerodynamic diameter smaller than 2.5 µm, and exposure to PM_2.5 can adversely damage human health. PM_2.5 may impair health through oxidative stress, inflammatory reactions, immune function alterations and chromosome or DNA damage. Through increasing in-depth studies, researchers have found that noncoding RNAs (ncRNAs), particularly microRNAs (miRNAs), circular RNAs (circRNAs) as well as long noncoding RNAs (lncRNAs), might play significant roles in PM_2.5-related human diseases via some of the abovementioned mechanisms. Therefore, in this review, we mainly discuss the regulatory function of ncRNAs altered by PM_2.5 in human diseases and summarize the potential molecular mechanisms. The findings reveal that these ncRNAs might induce or promote diseases via inflammation, the oxidative stress response, cell autophagy, apoptosis, cell junction damage, altered cell proliferation, malignant cell transformation, disruption of synaptic function and abnormalities in the differentiation and status of immune cells. Moreover, according to a bioinformatics analysis, the altered expression of potential genes caused by these ncRNAs might be related to the development of some human diseases. Furthermore, some ncRNAs, including lncRNAs, miRNAs and circRNAs, or processes in which they are involved may be used as biomarkers for relevant diseases and potential targets to prevent these diseases. Additionally, we performed a meta-analysis to identify more promising diagnostic ncRNAs as biomarkers for related diseases.

Association of PM2.5 Components with Acceleration of Aging: Moderating Role of Sex Hormones

Fine particulate matter (PM_2.5) has been linked to aging risk, and a lack of knowledge about the relationships between PM_2.5 components and aging risk impeded the development of healthy aging. Participants were recruited through a multicenter cross-sectional study in the Beijing-Tianjin-Hebei region in China. Middle-age and older males and menopausal women completed the collection of basic information, blood samples, and clinical examinations. The biological age was estimated by Klemera-Doubal method (KDM) algorithms based on clinical biomarkers. Multiple linear regression models were applied to quantify the associations and interactions while controlling for confounders, and a restricted cubic spline function estimated the corresponding dose-response curves of the relationships. Overall, KDM-biological age acceleration was associated with PM_2.5 component exposure over the preceding year in both males and females, with calcium [females: 0.795 (95% CI: 0.451, 1.138); males: 0.712 (95% CI: 0.389, 1.034)], arsenic [females: 0.770 (95% CI: 0.641, 0.899); males: 0.661 (95% CI: 0.532, 0.791)], and copper [females: 0.401 (95% CI: 0.158, 0.644); males: 0.379 (95% CI: 0.122, 0.636)] having greater estimates of the effect than total PM_2.5 mass. Additionally, we observed that the associations of specific PM_2.5 components with aging were lower in the higher sex hormone scenario. Maintaining high levels of sex hormones may be a crucial barrier against PM_2.5 component-related aging in the middle and older age groups.

Using a human bronchial epithelial cell-based malignant transformation model to explore the function of hsa-miR-200 family in the progress of PM2.5-induced lung cancer development

Numerous studies have revealed that ambient long-term exposure to fine particulate matter (PM_2.5) is significantly related to the development of lung cancer, but the molecular mechanisms of PM_2.5 exposure-induced lung cancer remains unknown. As an important epigenetic regulator, microRNAs (miRNAs) play vital roles in responding to environment exposure and various diseases including lung cancer development. Here we constructed a PM_2.5-induced malignant transformed cell model and found that miR-200 family, especially miR-200a-3p, was involved in the process of PM_2.5 induced lung cancer. Further investigation of the function of miR-200 family (miR-200a-3p as a representative revealed that miR-200a-3p promoted cell migration by directly suppressing TNS3 expression. These results suggested that ambient PM_2.5 exposure may increase the expression of miR-200 family and then promote the proliferation and migration of lung cancer cells. Our study provided novel model and insights into the molecular mechanism of ambient PM_2.5 exposure-induced lung cancer.

The Validity of Benchmark Dose Limit Analysis for Estimating Permissible Accumulation of Cadmium

Cadmium (Cd) is a toxic metal pollutant that accumulates, especially in the proximal tubular epithelial cells of kidneys, where it causes tubular cell injury, cell death and a reduction in glomerular filtration rate (GFR). Diet is the main Cd exposure source in non-occupationally exposed and non-smoking populations. The present study aimed to evaluate the reliability of a tolerable Cd intake of 0.83 μg/kg body weight/day, and its corresponding toxicity threshold level of 5.24 μg/g creatinine. The PROAST software was used to calculate the lower 95% confidence bound of the benchmark dose (BMDL) values of Cd excretion (E_Cd) associated with injury to kidney tubular cells, a defective tubular reabsorption of filtered proteins, and a reduction in the estimated GFR (eGFR). Data were from 289 males and 445 females, mean age of 48.1 years of which 42.8% were smokers, while 31.7% had hypertension, and 9% had chronic kidney disease (CKD). The BMDL value of E_Cd associated with kidney tubular cell injury was 0.67 ng/L of filtrate in both men and women. Therefore, an environmental Cd exposure producing E_Cd of 0.67 ng/L filtrate could be considered as Cd accumulation levels below which renal effects are likely to be negligible. A reduction in eGFR and CKD may follow when E_Cd rises from 0.67 to 1 ng/L of filtrate. These adverse health effects occur at the body burdens lower than those associated with E_Cd of 5.24 µg/g creatinine, thereby arguing that current health-guiding values do not provide a sufficient health protection.

Overview of particulate air pollution and human health in China: Evidence, challenges, and opportunities

Ambient particulate matter (PM) pollution in China continues to be a major public health challenge. With the release of the new WHO air quality guidelines in 2021, there is an urgent need for China to contemplate a revision of air quality standards (AQS). In the recent decade, there has been an increase in epidemiological studies on PM in China. A comprehensive evaluation of such epidemiological evidence among the Chinese population is central for revision of the AQS in China and in other developing countries with similar air pollution problems. We thus conducted a systematic review on the epidemiological literature of PM published in the recent decade. In summary, we identified the following: (1) short-term and long-term PM exposure increase mortality and morbidity risk without a discernible threshold, suggesting the necessity for continuous improvement in air quality; (2) the magnitude of long-term associations with mortality observed in China are comparable with those in developed countries, whereas the magnitude of short-term associations are appreciably smaller; (3) governmental clean air policies and personalized mitigation measures are potentially effective in protecting public and individual health, but need to be validated using mortality or morbidity outcomes; (4) particles of smaller size range and those originating from fossil fuel combustion appear to show larger relative health risks; and (5) molecular epidemiological studies provide evidence for the biological plausibility and mechanisms underlying the hazardous effects of PM. This updated review may serve as an epidemiological basis for China’s AQS revision and proposes several perspectives in designing future health studies.

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Acute effects of PM are smaller in China compared with developed countries

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Health effects caused by PM depend on particle composition, source, and size

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There are no thresholds for the health effects of PM

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Mechanistic studies support the biological plausibility of PM’s health effects

The role of PP2A /NLRP3 signaling pathway in ambient particulate matter 2.5 induced lung injury

Ambient particulate matter 2.5 (PM_2.5) exposure has been linked to pulmonary fibrosis. However, the key signaling pathways remained unclear. In the present study, we applied a mouse model with myeloid-specific deletion of Ppp2r1a gene (encoding protein phosphatase 2 A (PP2A) A subunit) to identify the key signaling pathways involved in PM_2.5-induced pulmonary fibrosis. PP2A Aα^-/- homozygote mice and matched wild-type (WT) littermates were exposed to filtered air (FA), unfiltered air (UA), and concentrated PM_2.5 (CA) in a real-ambient PM exposure system for 8 weeks and 16 weeks, respectively. The mice exposed to PM_2.5 displayed a progressive inflammation and pulmonary fibrosis. Moreover, the expressions of NLRP3, pro-caspase-1, caspase-1, ASC and IL-1β were increased in mice lung following PM_2.5 exposure, indicating PM_2.5 exposure caused pulmonary inflammation by the NLRP3 pathways activation. Furthermore, the effects of PM exposure on pulmonary inflammation, pulmonary fibrosis, oxidative stress, and pulmonary function damage were significantly enhanced in PP2A^-/- mice compared to WT mice, indicating the role of PP2A in the regulation of pulmonary injury induced by PM exposure. In vitro study confirmed that PP2A was involved in the PM_2.5-induced inflammation response and NLRP3 inflammasome activation. Importantly, we identified PP2A regulated the activation of NLRP3 pathways by direct dephosphorylating IRE1α in response to PM_2.5 exposure. Taken together, our results demonstrated that PP2A-IRE1α-NLRP3 signaling pathway played a crucial role in regulating the inflammation response, triggering the lung fibrogenesis upon PM_2.5 exposure. Our findings provide new insights into regulatory role of PP2A in human diseases upon the PM exposure.

Cross-sectional and longitudinal associations between urinary arsenic and lung function among urban Chinese adults

To investigate the associations of arsenic exposure with lung function and ventilatory impairment. The repeated-measures study was developed with 8479 observations from three study periods of the Wuhan-Zhuhai cohort. Urinary arsenic and lung function were measured during each period. Linear mixed models were used to estimate the cross-sectional and longitudinal relationships between urinary arsenic and lung function. Logistic regression models and COX regression models were used to evaluate the cross-sectional and longitudinal associations between urinary arsenic and ventilatory impairment, respectively. In the cross-sectional analysis, each 1-unit increase in log-transformed urinary arsenic was associated with a -22.499 mL (95 % confidence interval (CI): -35.832 to -9.165), -15.081 mL (-25.205 to -4.957), and -0.274 % (-0.541 to -0.007) change in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and FEV1/FVC, respectively. In the longitudinal analysis, each 1-unit increase in log-transformed urinary arsenic was associated with an annual change rate of -6.240 mL/year (95 % CI: -12.429 to -0.051), -5.855 mL/year (-10.632 to -1.079), and -0.143 %/year (-0.234 to -0.051) in FVC, FEV1, and FEV1/FVC, respectively. Stratified analyses suggested a modification role of gender on the cross-sectional and longitudinal associations between urinary arsenic and FEV1, with the stronger associations were found among males (P for modification 0.0384 and 0.0168). Furtherly, each 1-unit increase in log-transformed urinary arsenic was associated with a 14.8 % (odds ratio 1.148, 95 % CI: 1.043 to 1.263) and 11.7 % (hazard ratio 1.117, 95 % CI: 1.023 to 1.218) increase in the prevalent and incident risk of restrictive ventilatory impairment, respectively. Source analyses suggested that fish intake and fine particulate matter inhalation positively associated with the total arsenic levels. In conclusion, arsenic exposure was associated with lung function decline and the risk of restrictive ventilatory impairment.

Mitigation of Cadmium Toxicity through Modulation of the Frontline Cellular Stress Response

Cadmium (Cd) is an environmental toxicant of public health significance worldwide. Diet is the main Cd exposure source in the non-occupationally exposed and non-smoking populations. Metal transporters for iron (Fe), zinc (Zn), calcium (Ca), and manganese (Mn) are involved in the assimilation and distribution of Cd to cells throughout the body. Due to an extremely slow elimination rate, most Cd is retained by cells, where it exerts toxicity through its interaction with sulfur-containing ligands, notably the thiol (-SH) functional group of cysteine, glutathione, and many Zn-dependent enzymes and transcription factors. The simultaneous induction of heme oxygenase-1 and the metal-binding protein metallothionein by Cd adversely affected the cellular redox state and caused the dysregulation of Fe, Zn, and copper. Experimental data indicate that Cd causes mitochondrial dysfunction via disrupting the metal homeostasis of this organelle. The present review focuses on the adverse metabolic outcomes of chronic exposure to low-dose Cd. Current epidemiologic data indicate that chronic exposure to Cd raises the risk of type 2 diabetes by several mechanisms, such as increased oxidative stress, inflammation, adipose tissue dysfunction, increased insulin resistance, and dysregulated cellular intermediary metabolism. The cellular stress response mechanisms involving the catabolism of heme, mediated by heme oxygenase-1 and -2 (HO-1 and HO-2), may mitigate the cytotoxicity of Cd. The products of their physiologic heme degradation, bilirubin and carbon monoxide, have antioxidative, anti-inflammatory, and anti-apoptotic properties.

Associations of Exposure to Fine Particulate Matter Mass and Constituents with Systemic Inflammation: A Cross-Sectional Study of Urban Older Adults in China

Systemic inflammation is a key mechanism in the development of cardiovascular diseases induced by exposure to fine particles (particles with aerodynamic diameter ≤2.5 μm [PM_2.5]). However, little is known about the effects of chemical constituents of PM_2.5 on systemic inflammation. In this cross-sectional study, filter samples of personal exposure to PM_2.5 were collected from community-dwelling older adults in Tianjin, China, and the chemical constituents of PM_2.5 were analyzed. Blood samples were collected immediately after the PM_2.5 sample collection. Seventeen cytokines were measured as targets. A linear regression model was applied to estimate the relative effects of PM_2.5 and its chemical constituents on the measured cytokines. A positive matrix factorization model was employed to distinguish the sources of PM_2.5. The calculated source contributions were used to estimate their effects on cytokines. After adjusting for other covariates, higher PM_2.5-bound copper was significantly associated with increased levels of interleukin (IL)1β, IL6, IL10, and IL17 levels. Source analysis showed that an increase in PM_2.5 concentration that originated from tire/brake wear and cooking emissions was significantly associated with enhanced levels of IL1β, IL6, tumor necrosis factor alpha (TNFα), and IL17. In summary, personal exposure to some PM_2.5 constituents and specific sources could increase systemic inflammation in older adults. These findings may explain the cardiopulmonary effects of specific particulate chemical constituents of urban air pollution.

Personal PM2.5-bound PAH exposure, oxidative stress and lung function: The associations and mediation effects in healthy young adults

Decreased lung function is an early hazard of respiratory damage from fine particulate matter (PM_2.5) exposure. Limited studies have explored the association between PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) and lung function, but studies at the personal level in healthy young adults are scarce. Here, we assessed personal PM_2.5 and PM_2.5-bound PAH levels in a panel of 45 healthy young adults by a time-weighted model. The aims were to investigate the relationship between personal exposure and lung function by a linear mixed effect model, and to explore the mediating effects of oxidative stress in this association. The results showed that personal exposure to PM_2.5 and PAHs had the greatest negative effect on forced expiratory volume in 1 s (FEV₁), peak expiratory flow rate (PEF) and forced expiratory flow between 25% and 75% vital capacity (FEF_25-75) at lag 3 days. An IQR increase in personal PM_2.5 exposure was associated with a change of 0.35% (95% CI: 0.27%, 0.42%) in FEV₁, 0.39% (95% CI: 0.29%, 0.47%) in PEF and 0.36% (95% CI: 0.27%, 0.45%) in FEF_25-75. An IQR increase in personal PAH exposure was associated with a decrease of 0.63% (95% CI: 0.55%, 0.69%) in FEV₁, 0.69% (95% CI: 0.61%, 0.75%) in PEF and 0.66% (95% CI: 0.57%, 0.72%) in FEF_25-75. Additionally, exposure to PM_2.5 and PAHs resulted in the strongest positive effects on urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin-F_2α (8-iso-PGF_2α). Of these, 8-OHdG mediated 10.33%, 8.87% and 9.45% of the associations of personal PM_2.5 exposure with FEV₁, PEF and FEF_25-75, respectively. Our results revealed that personal exposure to PM_2.5 and PAHs was associated with lung function decline in healthy young adults, and urinary 8-OHdG mediated the association between personal PM_2.5 and lung function.

Evidence for Ovarian and Testicular Toxicities of Cadmium and Detoxification by Natural Substances

Cadmium (Cd) is an environmental toxicant, capable of reducing mitochondrial ATP production and promoting the formation of reactive oxygen species (ROS) with resultant oxidative stress conditions. The ovary and testis are the primary gonads in which female gametes (oocytes) and male gametes (spermatozoa), estrogen and testosterone are produced. These organs are particularly susceptible to Cd cytotoxicity due to their high metabolic activities and high energy demands. In this review, epidemiological and experimental studies examining Cd toxicities in gonads are highlighted together with studies using zinc (Zn), selenium (Se), and natural substances to reduce the effects of Cd on follicular genesis and spermatogenesis. Higher blood concentrations of Cd ([Cd]b) were associated with longer time-to-pregnancy in a prospective cohort study. Cd excretion rate (ECd) as low as 0.8 μg/g creatinine was associated with reduced spermatozoa vitality, while Zn and Se may protect against spermatozoa quality decline accompanying Cd exposure. ECd > 0.68 µg/g creatinine were associated with an increased risk of premature ovarian failure by 2.5-fold, while [Cd]b ≥ 0.34 µg/L were associated with a 2.5-fold increase in the risk of infertility in women. Of concern, urinary excretion of Cd at 0.68 and 0.8 μg/g creatinine found to be associated with fecundity are respectively 13% and 15% of the conventional threshold limit for Cd-induced kidney tubular effects of 5.24 μg/g creatinine. These findings suggest that toxicity of Cd in primary reproductive organs occurs at relatively low body burden, thereby arguing for minimization of exposure and environmental pollution by Cd and its transfer to the food web.

Environmental and Occupational Short-Term Exposure to Airborne Particles and FEV1 and FVC in Healthy Adults: A Systematic Review and Meta-Analysis

Background: No study has compared the respiratory effects of environmental and occupational particulate exposure in healthy adults. Methods: We estimated, by a systematic review and meta-analysis, the associations between short term exposures to fine particles (PM_2.5 and PM₄) and certain parameters of lung function (FEV₁ and FVC) in healthy adults. Results: In total, 33 and 14 studies were included in the qualitative synthesis and meta-analyses, respectively. In environmental studies, a 10 µg/m³ increase in PM_2.5 was associated with an FEV₁ reduction of 7.63 mL (95% CI: −10.62 to −4.63 mL). In occupational studies, an increase of 10 µg/m³ in PM₄ was associated with an FEV₁ reduction of 0.87 mL (95% CI: −1.36 to −0.37 mL). Similar results were observed with FVC. Conclusions: Both occupational and environmental short-term exposures to fine particles are associated with reductions in FEV₁ and FVC in healthy adults.

Association of multi-metals exposure with intelligence quotient score of children: A prospective cohort study

BACKGROUND

Associations between most single metals and children's intelligence quotient (IQ) scores have been evaluated in previous studies. However, associations between multi-metal exposures and children's IQ scores have not been analyzed.

OBJECTIVES

To assess the joint effects of lead (Pb), manganese (Mn), antimony (Sb), tin (Sn) and titanium (Ti) co-exposure on children's IQ scores.

METHODS

A prospective cohort study was conducted in Shimen and Huayuan, Hunan Province, China. Urine metals levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) at baseline. Children's IQ scores were repeatedly measured at baseline and follow-up following the method of Raven's Standard Progressive Matrices (SPM) and standardized as z scores. We fitted linear regression models and Bayesian kernel machine regression (BKMR) models to investigate the associations of metal levels with children's IQ scores after adjusting for covariates.

RESULTS

A total of 633 participants aged 7-10 years completed the survey. Urinary Pb (β = -0.028, P = 0.022) and urinary Ti (β = -0.0003, P = 0.001) were inversely associated with children's IQ scores. The BKMR analyses revealed significant negative overall effects of the five metals on children's IQ scores when all the metals were above their median levels, while significant positive associations were shown when all the metal concentrations were below their median levels. The model also showed negative trends of Sn and Ti on children's IQ. Furthermore, Ti and Sn had a synergistic relationship, with a decline in IQ score when Sn exposure was relatively high. The urinary Sn concentration was significantly higher but the urinary Ti concentration was significantly lower in participants from the Shimen area than in those from the Huayuan area. Decreasing trends of the overall effects were observed in both the Shimen and Huayuan areas.

CONCLUSION

Our findings revealed that multi-metal exposures caused a decline in children's IQ scores according to traditional linear regression models and the BKMR model. Our results provide some evidence of the association between multi-metal exposure and children's IQ. Meanwhile, interactions between multi-metal exposures on children's IQ should be given more attention.

Urinary metabolites of polycyclic aromatic hydrocarbons after short-term fine particulate matter exposure: A randomized crossover trial of air filtration

Research on the relationship between short-term exposure to fine particulate matter (PM_2.5) and urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) is sparse in the nonoccupationally exposed populations. A quasi-experimental observation of haze events nested within a randomized crossover trial of alternative 1-week real or sham indoor air filtration was conducted to evaluate the associations of urinary monohydroxy-PAHs (OH-PAHs) with short-term exposure to PM_2.5 and PM_2.5-bound PAHs. The study was conducted among 57 healthy college students in Beijing, China. PM_2.5-bound PAHs and urinary OH-PAHs were quantified using gas chromatography coupled with a triple-quadrupole tandem mass spectrometer. Linear mixed-effect models were applied to evaluate the association of urinary OH-PAHs with time-weighted personal PM_2.5 and PM_2.5-bound PAHs, controlling for potentially confounding variables. The results demonstrated that air filtration could markedly reduce external exposure to PM_2.5 and PM_2.5-bound parent, nitrated, and oxygenated PAHs. In the intervention trial, the urinary concentrations of 2-hydroxyfluorene (2-OH-FLU) and 9-hydroxyphenanthrene (9-OH-PHE) were elevated significantly by 16.5% (95% CI, 2.1%, 33.1%) and 37.9% (95% CI, 8.4%, 75.4%), respectively, in association with a doubling increase in personal PM_2.5 exposure. Urinary 9-OH-PHE was also significantly positively associated with the increase in the sum of PM_2.5-bound parent PAHs. Furthermore, the levels of urinary OH-PAHs such as 2-OH-FLU and 9-OH-PHE in the haze events were elevated by 31.1% (95% CI, 8.7%, 53.4%) and 73.5% (95% CI, 16.0%, 131.0%), respectively, in association with a doubling increase in personal PM_2.5 exposure. The findings indicated that urinary 2-OH-FLU and 9-OH-PHE could serve as potential internal exposure biomarkers for assessing short-term PM_2.5 exposure in nonoccupational populations.

Chemical constituents and sources of indoor PM2.5 and cardiopulmonary function in patients with chronic obstructive pulmonary disease: Estimation of individual and joint effects

BACKGROUND

The cardiopulmonary effects of chemical constituents and sources of indoor fine particulate matter (PM_2.5) remain unclear.

OBJECTIVES

To examine the individual and joint effects of constituents of indoor PM_2.5 on cardiopulmonary function of patients with chronic obstructive pulmonary disease (COPD) and the role of identified sources.

METHODS

This panel study recruited 43 stable COPD patients from November 2015 to May 2016 in Beijing, China. Daily indoor and outdoor PM_2.5 were collected for five consecutive days simultaneously. Twenty-four elements were measured and principal component analysis was used for source appointment. Pulmonary function and blood pressure (BP) were also measured at daily visit. The linear mixed-effect models were used to estimate the effect of each constituent and source. Bayesian kernel machine regression (BKMR) models were used to estimate the overall effect of all measured constituents.

RESULTS

The combustion, indoor soil/dust and road dust sources were identified as the main sources of indoor PM_2.5 and combustion sources contributed over 40% during the heating season. Most constituents were significantly associated with elevated BP of COPD patients and the joint effects of mixed exposures were also significant especially during the heating season. Most associations of chemical constituents with pulmonary function were negative but not statistically significant during the heating season, as was the joint effect. Few associations were observed during the non-heating season. Further, we observed combustion sources throughout the study period and road dust sources during the heating season were significantly associated with increased BP but not decreased pulmonary function.

CONCLUSION

The combustion and road dust sources and their related constituents of indoor PM_2.5 could cause adverse effects on cardiovascular function of COPD patients especially during the heating season, but the effect on pulmonary function still needs to be further studied.

Acute effects of fine particulate matter constituents on cardiopulmonary function in a panel of COPD patients

BACKGROUND

Exposure to fine particulate matter (PM_2.5) has been linked with adverse cardiorespiratory health conditions. However, evidence for PM_2.5 constituents is still scarce, especially among patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To investigate the associations of short-term exposure to different chemical constituents of PM_2.5 with measures of cardiac and lung function in COPD patients.

METHODS

We conducted a retrospective panel study among 100 COPD patients who received repeated measures of left ventricular ejection fraction (LVEF), forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and peak expiratory flow (PEF) in Shanghai, China from August 2014 to September 2019. Daily PM_2.5 and PM_2.5 constituents were obtained from fixed-site monitoring station. Linear mixed-effects models were used to estimate the associations of PM_2.5.

RESULTS

We found water-soluble ions of PM_2.5, mainly NO₃^-, SO₄^2-, and NH₄⁺ were robustly associated with reduced LVEF, and the reductions in LVEF associated with an IQR increase of them ranged from 1.8% to 2.0% (lag 1 d). Metal constituents such as Cu and As were associated with FEV₁, FVC and PEF. The corresponding reductions in lung function parameters for an IQR increase of them ranged from 1.4% to 2.3% (lag 0 or 1 d). These associations remained relatively robust after adjusting for total PM_2.5 mass and gaseous pollutants.

CONCLUSIONS

Our results suggest that water-soluble ions and several metal/metalloid elements might be important constituents in PM_2.5 that were associated with reduced cardiorespiratory function among COPD patients.

No more waste at the elemental analysis of airborne particulate matter on quartz fibre filters

Particulate matter (PM) is the major environmental pollutant. Its elemental composition is routinely monitored. Inductively coupled plasma mass spectroscopy (ICPMS) is commonly applied after a PM sample has been digested by an acid during a microwave treatment. In this case, sample preparation procedure is laborious, sometimes incomplete and produces toxic waste. In this paper we show that direct sample introduction to ICPMS by laser ablation (LA-ICPMS) is of huge advantage. Minimal quantity of a sample is required for the analysis (<1 cm²) and no chemical waste is produced. The study focused on the most universal and widely used quartz fibre filter samples and we show that LA-ICPMS can be successfully applied for the determination of the elemental composition of such samples. Some effort is, however, still needed to develop an autosampler for the LA-ICPMS system and to provide commercial matrix-matched standards for this application to be implemented in environment laboratories worldwide.

The association between urinary aluminum and lung function among an urban adult population: A repeated-measure longitudinal study

OBJECTIVES

To investigate the cross-sectional and longitudinal associations between aluminum exposure and lung function and the risk of chronic obstructive pulmonary disease (COPD).

METHODS

The repeated-measure study was developed with 3917 adults from the Wuhan-Zhuhai cohort and they were followed-up after 3 years and 6 years. Urinary aluminum and lung function were measured at each period. Linear mixed models were used to estimate the exposure-response relationship between urinary aluminum and lung function. COX regression models were used to evaluate the association of urinary aluminum with the risk of COPD.

RESULTS

A total of 6996 observations including 2251 (32.2%) males with a mean age of 54.8 years were included. In the cross-sectional analyses, each 1-unit increase in log-transformed urinary aluminum was associated with a -33.34 mL (95% confidence interval (CI) -45.71 to -20.96) change in forced vital capacity (FVC) and a -17.89 mL (-27.80 to -7.97) change in forced expiratory volume in 1 s (FEV1). The follow-up analyses detected a negative association between urinary aluminum and the annual change of FVC (-6.73 mL/year, 95% CI -10.92 to -2.54), while the association of annual decline of FEV1 with urinary aluminum was statistically insignificant (-2.26 mL/year, -5.76 to 1.23). In the adjusted COX regression model, each 1-unit increase in log-transformed urinary aluminum was associated with a 29% increase in the incident risk of COPD (hazard ratio 1.29, 95% CI 1.04-1.62).

INCLUSION

Increased urinary aluminum was associated with lung function reduction and the increased risk of COPD in a general urban population.

COVID-19 Infection and Mortality: Association with PM2.5 Concentration and Population Density—An Exploratory Study

The novel coronavirus disease (COVID-19) has become a public health problem at a global scale because of its high infection and mortality rate. It has affected most countries in the world, and the number of confirmed cases and death toll is still growing rapidly. Susceptibility studies have been conducted in specific countries, where COVID-19 infection and mortality rates were highly related to demographics and air pollution, especially PM2.5, but there are few studies on a global scale. This paper is an exploratory study of the relationship between confirmed COVID-19 cases and death toll per million population, population density, and PM2.5 concentration on a worldwide basis. A multivariate linear regression based on Moran eigenvector spatial filtering model and Geographically weighted regression model were undertaken to analyze the relationship between population density, PM2.5 concentration, and COVID-19 infection and mortality rate, and a geostatistical method with bivariate local spatial association analysis was adopted to explore their spatial correlations. The results show that there is a statistically significant positive relationship between COVID-19 confirmed cases and death toll per million population, population density, and PM2.5 concentration, but the relationship displays obvious spatial heterogeneity. While some adjacent countries are likely to have similar characteristics, it suggests that the countries with close contacts/sharing borders and similar spatial pattern of population density and PM2.5 concentration tend to have similar patterns of COVID-19 risk. The analysis provides an interpretation of the statistical and spatial association of COVID-19 with population density and PM2.5 concentration, which has implications for the control and abatement of COVID-19 in terms of both infection and mortality.

Fine and coarse particulate matter, trace element content, and associated health risks considering respiratory deposition for Ergene Basin, Thrace

Ergene Basin is located in Thrace, Turkey, where industries are densely populated. This study aimed to determine exposure of people living in Ergene Basin (Çorlu and Çerkezköy) to fine and coarse PM, and its potentially toxic element (PTE) content by considering variation in respiratory airway deposition rates with daily activities and PM particle size by employing deposition models of International Commission on Radiological Protection and Multiple Path Particle Dosimetry. Fine and coarse PM samples were collected daily for a year at points in Çorlu and Çerkezköy representing urban and industrial settings, respectively. A questionnaire survey was conducted in the study area to obtain time-activity budgets, and associated variation was included in the health risk assessment by considering time-activity-dependent inhalation rates. The studied PTEs were Al, As, Ba, Cd, Cr, Co, Mn, Ni, Pb, and Se. The mean fine and coarse PM concentrations were measured as 23 and 14 μg/m³ in Çorlu, and 22 and 12 μg/m³ in Çerkezköy, respectively. The only PTE that exceeded acceptable risk in terms of total carcinogenic risk was Cr. Non-carcinogenic risks of all the PTEs including Cr were below the threshold. The use of deposition fractions in the health risk assessment (HRA) calculations was found to prevent overestimation of health risks by at least 91% and 87% for fine and coarse PM, respectively, compared to the regular HRA. Minor differences in risk between Çorlu and Çerkezköy suggest that urban pollution sources could be at least as influential on human health as industrial sources.

Health effects of occupational exposure to printer emissions on workers in China: Cardiopulmonary function change

Printers emitted nanoparticles (NPs), ozone (O₃) and volatile organic chemicals (VOCs) during operation that elicited adverse effects on indoor air quality of the printing room, which may affect the health of exposed workers. The aim of this work was to explore the health effects of occupational exposure to printer emissions on workers, especially cardiovascular and lung function. We sampled particles in the print shop for characterization, including particle size distribution and elemental composition, and measured PM₁ number concentrations in print shops and other workplaces. We assessed blood pressure, heart rate and pulmonary function in 53 printing room workers and 54 controls in Beijing, China. Multiple linear regression analysis were used to examine health effects of exposure to printer emissions. The PM₁ number concentration in the print shop was more than 2 times that of the control group. Compared with controls, the exposed workers with lower education and income had heavier workload with a median of 7 days per week and 12 h per day on working days, and presented cardiopulmonary function injury with increased the diastolic blood pressure (DBP), systolic blood pressure (SBP), and mean arterial pressure (MAP). The most significant changes of cardiopulmonary function were found in exposed workers with more than 10 years of working age. Multiple linear regression also showed printer emissions exposure was associated with increased SBP and MAP, while decreased lung function indices. This study found changes in the cardiopulmonary function of staff members exposed to printer emissions, which prompted the necessity and urgency of improving the environment of printing rooms and protecting the health of exposed workers.

Low levels of fine particulate matter increase vascular damage and reduce pulmonary function in young healthy adults

BACKGROUND

Fine particulate matter (PM2.5) related mild inflammation, altered autonomic control of cardiovascular function, and changes to cell function have been observed in controlled human exposure studies.

METHODS

To measure the systemic and cardiopulmonary impacts of low-level PM exposure, we exposed 20 healthy, young volunteers to PM2.5, in the form of concentrated ambient particles (mean: 37.8 μg/m3, SD 6.5), and filtered air (mean: 2.1 μg/m3, SD 2.6). In this double-blind, crossover study the exposure order was randomized. During the 4 h exposure, volunteers (7 females and 13 males) underwent light intensity exercise to regulate ventilation rate. We measured pulmonary, cardiac, and hematologic end points before exposure, 1 h after exposure, and again 20 h after exposure.

RESULTS

Low-level PM2.5 resulted in both pulmonary and extra-pulmonary changes characterized by alterations in systematic inflammation markers, cardiac repolarization, and decreased pulmonary function. A mean increase in PM2.5 concentration (37.8 μg/m3) significantly increased serum amyloid A (SAA), C-reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1), 1 h after exposure by 8.7, 9.1, 10.7, and 6.6%, respectively, relative to the filtered air control. SAA remained significantly elevated (34.6%) 20 h after PM2.5 exposure which was accompanied by a 5.7% decrease in percent neutrophils. Decreased pulmonary function was observed 1 h after exposure through a 0.8 and 1.2% decrease in forced expiratory volume in 1 s (FEV1) and FEV1/ forced vital capacity (FEV1/FVC) respectively. Additionally, sex specific changes were observed in repolarization outcomes following PM2.5 exposure. In males, P-wave and QRS complex were increased by 15.4 and 5.4% 1 h after exposure.

CONCLUSIONS

This study is the first controlled human exposure study to demonstrate biological effects in response to exposure to concentrated ambient air PM2.5 particles at levels near the PM2.5 US NAAQS standard.

CLINICAL TRIAL REGISTRATION INFORMATION

clinicaltrials.gov ; Identifier: NCT03232086 . The study was registered retrospectively on July 25, 2017, prior to final data collection on October 25, 2017 and data analysis.

Cadmium and Lead Exposure, Nephrotoxicity, and Mortality

The present review aims to provide an update on health risks associated with the low-to-moderate levels of environmental cadmium (Cd) and lead (Pb) to which most populations are exposed. Epidemiological studies examining the adverse effects of coexposure to Cd and Pb have shown that Pb may enhance the nephrotoxicity of Cd and vice versa. Herein, the existing tolerable intake levels of Cd and Pb are discussed together with the conventional urinary Cd threshold limit of 5.24 μg/g creatinine. Dietary sources of Cd and Pb and the intake levels reported for average consumers in the U.S., Spain, Korea, Germany and China are summarized. The utility of urine, whole blood, plasma/serum, and erythrocytes to quantify exposure levels of Cd and Pb are discussed. Epidemiological studies that linked one of these measurements to risks of chronic kidney disease (CKD) and mortality from common ailments are reviewed. A Cd intake level of 23.2 μg/day, which is less than half the safe intake stated by the guidelines, may increase the risk of CKD by 73%, and urinary Cd levels one-tenth of the threshold limit, defined by excessive ß₂-microglobulin excretion, were associated with increased risk of CKD, mortality from heart disease, cancer of any site and Alzheimer's disease. These findings indicate that the current tolerable intake of Cd and the conventional urinary Cd threshold limit do not provide adequate health protection. Any excessive Cd excretion is probably indicative of tubular injury. In light of the evolving realization of the interaction between Cd and Pb, actions to minimize environmental exposure to these toxic metals are imperative.

Temporal trend of arsenic in outdoor air PM2.5 in Wuhan, China, in 2015-2017 and the personal inhalation of PM-bound arsenic: implications for human exposure

Arsenic in fine air particulate matter (PM_2.5) has been identified as an important factor responsible for the morbidity of lung cancer, which has increased sharply in many regions of China. Some reports in China have shown that arsenic in the air exceeds the ambient air quality standard value, while long-term airborne arsenic concentrations in central China and human exposure via inhalation of PM-bound arsenic (inhalable airborne PM) have not been well characterized. In this study, 579 outdoor air PM_2.5 samples from Wuhan, a typical city in central China, were collected from 2015 to 2017, and arsenic was measured by inductively coupled plasma-mass spectrometry. Personal exposure to PM-bound arsenic via inhalation and urinary arsenic concentration were also measured. The concentrations of arsenic in PM_2.5 were in the range of 0.42-61.6 ng/m³ (mean 8.48 ng/m³). The average concentration of arsenic in 2015 (10.7 ng/m³) was higher than that in 2016 (6.81 ng/m³) and 2017 (8.18 ng/m³), exceeded the standard value. The arsenic concentrations in spring and winter were higher than those in summer and autumn. No significant differences (p > 0.05) were found among different sites. The daily intake of arsenic inhalation based on PM₁₀ samples collected by personal samplers (median, 10.8 ng/m³) was estimated. Urban residents inhaled higher levels of PM-bound arsenic than rural residents. Daily intake of arsenic via inhalation accounted for a negligible part (< 1%) of the total daily intake of arsenic (calculated based on excreted urinary arsenic); however, potential associations between the adverse effects (e.g., lung adenocarcinoma) and inhaled PM-bound arsenic require more attention, particularly for those who experience in long-term exposure. This study is the first report of a 3-year temporal trend of airborne PM_2.5-bound arsenic in central China.

Industrial Air Pollution and Respiratory Health Status among Residents in an Industrial Area in Central Italy

The area of Civitavecchia (Lazio region, Central Italy) has been a reason of concern in the past because of environmental air contamination. The aim of this study was to evaluate the association between air pollution from different sources and respiratory symptoms and lung function in the population. A sample of 1177 residents underwent medical examination and lung function tests. Information on individual characteristics, histories of exposure and medical history were collected through a validated questionnaire. Long-term exposure to industrial, harbour, biomass combustion emissions (PM₁₀) and urban traffic (NO_x) at residential address was assessed using a Lagrangian dispersion model. The associations between exposure and wheezing and dyspnea were assessed using logistic regression models, while modified Poisson regression models were used to evaluate cough with phlegm. Relationships between exposure and lung function were analysed using linear mixed-effects models and cross-correlation. PM10 emissions from the harbour were associated with lower lung function parameters (FEV1: β = –0.12, 95% CI –0.21 –0.03; p = 0.02; FEV1/FVC: β = –1.67, (–3.10 –0.23); p = 0.02. This association was observed also in healthy subjects, but not in females. We found, even if at low exposure level, an effect of environmental PM₁₀ exposure from harbour on lung function.

Toxic Effects of Particulate Matter Derived from Dust Samples Near the Dzhidinski Ore Processing Mill, Eastern Siberia, Russia

Ambient particulate matter (PM) is associated with increased mortality and morbidity, an effect influenced by the metal components of the PM. We characterized five sediment samples obtained near a tungsten-molybdenum ore-processing complex in Zakamensk, Russia for elemental composition and PM toxicity with regard to pulmonary, vascular, and neurological outcomes. Elemental and trace metals analysis of complete sediment and PM₁₀ (the respirable fraction, < 10 µm mass mean aerodynamic diameter) were performed using inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS). Sediment samples and PM₁₀ consisted largely of silicon and iron and silicon and sodium, respectively. Trace metals including manganese and uranium in the complete sediment, as well as copper and lead in the PM₁₀ were observed. Notably, metal concentrations were approximately 10 × higher in the PM₁₀ than in the sediment. Exposure to 100 µg of PM₁₀ via oropharyngeal aspiration in C56BL/6 mice resulted in pulmonary inflammation across all groups. In addition, mice exposed to three of the five PM₁₀ samples exhibited impaired endothelial-dependent relaxation, and correlative analysis revealed associations between pulmonary inflammation and levels of lead and cadmium. A tendency for elevated cortical ccl2 and Tnf-α mRNA expression was induced by all samples and significant upregulation was noted following exposure to PM₁₀ samples Z3 and Z4, respectively. Cortical Nqo1 mRNA levels were significantly upregulated in mice exposed to PM₁₀ Z2. In conclusion, pulmonary exposure to PM samples from the Zakamensk region sediments induced varied pulmonary and systemic effects that may be influenced by elemental PM composition. Further investigation is needed to pinpoint putative drivers of neurological outcomes.

Endogenous doesn't always mean innocuous: a scoping review of iron toxicity by inhalation

Ambient air pollution is a leading risk factor for the global burden of disease. One possible pathway of particulate matter (PM)-induced toxicity is through iron (Fe), the most abundant metal in the atmosphere. The aim of the review was to consider the complexity of Fe-mediated toxicity following inhalation exposure focusing on the chemical and surface reactivity of Fe as a transition metal and possible pathways of toxicity via reactive oxygen species (ROS) generation as well as considerations of size, morphology, and source of PM. A broad term search of 4 databases identified 2189 journal articles and reports examining exposure to Fe via inhalation in the past 10 years. These were sequentially analyzed by title, abstract and full-text to identify 87 articles publishing results on the toxicity of Fe-containing PM by inhalation or instillation to the respiratory system. The remaining 87 papers were examined to summarize research dealing with in vitro, in vivo and epidemiological studies involving PM containing Fe or iron oxide following inhalation or instillation. The major findings from these investigations are summarized and tabulated. Epidemiological studies showed that exposure to Fe oxide is correlated with an increased incidence of cancer, cardiovascular diseases, and several respiratory diseases. Iron PM was found to induce inflammatory effects in vitro and in vivo and to translocate to remote locations including the brain following inhalation. A potential pathway for the PM-containing Fe-mediated toxicity by inhalation is via the generation of ROS which leads to lipid peroxidation and DNA and protein oxidation. Our recommendations include an expansion of epidemiological, in vivo and in vitro studies, integrating research improvements outlined in this review, such as the method of particle preparation, cell line type, and animal model, to enhance our understanding of the complex biological interactions of these particles.

Short-term impacts of ambient fine particulate matter on emergency department visits: Comparative analysis of three exposure metrics

BACKGROUND

Research argued that daily excessive concentration hours (DECH) could be more informative through accounting for within-day variations, when assessing population-level exposure to ambient fine particle (PM_2.5). However, few studies have comparatively investigated PM_2.5-associated risks using DECH and two common metrics of daily mean and hourly peak concentration.

METHODS

We collected daily records of all-cause emergency department visits (EDVs) and hourly data on air pollutants and meteorological factors from Shenzhen, China, 2015-2018. According to guidelines proposed by the World Health Organization, DECH was calculated by summing up daily concentrations exceeding 25 μg/m³. Based on time-stratified case-crossover design, we adopted conditional logistic regression models to assess short-term attributable risks of EDVs associated with PM_2.5 using three exposure metrics.

RESULTS

DECH and daily average of PM_2.5 strongly elevated risks of EDVs, while less evident associations were observed using hourly peak metric. Estimated excess relative risks at lag 0 day were 0.56% (95% confidence interval [CI]: 0.21 to 0.91), 0.69% (95% CI: 0.25 to 1.13) and 0.37% (95% CI: 0.02 to 0.76), respectively, associated with an interquartile range increase in DECH (420.2 μg/m³), 24-h average (24.9 μg/m³) and hourly peak concentration (38 μg/m³). More emergency visits could be attributed to DECH than daily mean PM_2.5, with attributable fractions of 2.02% (95% CI: 1.42 to 2.61) and 1.09% (95% CI: 0.69 to 1.49), respectively.

CONCLUSIONS

This study added evidence for increased risk of EDVs associated with exposure to ambient PM_2.5. DECH was a potential alternative exposure metric for PM_2.5 assessment, which may have implications for future revision of air quality standards.

Association of emergency room visits for respiratory diseases with sources of ambient PM2.5

Previous studies have reported associations of short-term exposure to different sources of ambient fine particulate matter (PM_2.5) and increased mortality or hospitalizations for respiratory diseases. Few studies, however, have focused on the short-term effects of source-specific PM_2.5 on emergency room visits (ERVs) of respiratory diseases. Source apportionment for PM_2.5 was performed with Positive Matrix Factorization (PMF) and generalized additive model was applied to estimate associations between source-specific PM_2.5 and respiratory disease ERVs. The association of PM_2.5 and total respiratory ERVs was found on lag4 (RR = 1.011, 95%CI: 1.002, 1.020) per interquartile range (76 μg/m³) increase. We found PM_2.5 to be significantly associated with asthma, bronchitis and chronic obstructive pulmonary disease (COPD) ERVs, with the strongest effects on lag5 (RR = 1.072, 95%CI: 1.024, 1.119), lag4 (RR = 1.104, 95%CI: 1.032, 1.176) and lag3 (RR = 1.091, 95%CI: 1.047, 1.135), respectively. The estimated effects of PM_2.5 changed little after adjusting for different air pollutants. Six primary PM_2.5 sources were identified using PMF analysis, including dust/soil (6.7%), industry emission (4.5%), secondary aerosols (30.3%), metal processing (3.2%), coal combustion (37.5%) and traffic-related source (17.8%). Some of the sources were identified to have effects on ERVs of total respiratory diseases (dust/soil, secondary aerosols, metal processing, coal combustion and traffic-related source), bronchitis ERVs (dust/soil) and COPD ERVs (traffic-related source, industry emission and secondary aerosols). Different sources of PM_2.5 contribute to increased risk of respiratory ERVs to different extents, which may provide potential implications for the decision making of air quality related policies, rational emission control and public health welfare.

Associations of chemical composition and sources of PM2.5 with lung function of severe asthmatic adults in a low air pollution environment of urban Nagasaki, Japan

Previous studies have linked ambient PM_2.5 to decreased pulmonary function, but the influence of specific chemical elements and emission sources on the severe asthmatic is not well understood. We examined the mass, chemical constituents, and sources of PM_2.5 for short-term associations with the pulmonary function of adults with severe asthma in a low air pollution environment in urban Nagasaki, Japan. We recruited 35 asthmatic adults and obtained the daily record of morning peak expiratory flow (PEF) in spring 2014-2016. PM_2.5 filters were extracted from an air quality monitoring station (178 days) and measured for 27 chemical elements. Source apportionment was performed using Positive Matrix Factorization (PMF). We fitted generalized linear model with generalized estimating equation (GEE) method to estimate changes in PEF (from personal monthly maximum) and odds of severe respiratory deterioration (first ≥ 15% PEF reduction within a 1-week interval) associated with mass, constituents, and sources of PM_2.5, with adjustment for temperature and relative humidity. Constituent sulfate (SO₄^2-) and PM_2.5 from oil combustion and traffic were associated with reduced PEF. An interquartile range (IQR) increase in SO₄^2- (3.7 μg/m³, average lags 0-1) was associated with a decrease of 0.38% (95% confidence interval = -0.75% to -0.001%). An IQR increase in oil combustion and traffic-sourced PM_2.5 (2.64 μg/m³, lag 1) was associated with a decrease of 0.33% (-0.62% to -0.002%). We found a larger PEF decrease associated with PM_2.5 from dust/soil on Asian Dust days. There was no evidence linking total mass and metals to reduced pulmonary function. The ventilatory capacity of adults with severe asthma is susceptible to specific constituents/sources of PM_2.5 such as sulfate and oil combustion and traffic despite active self-management of asthma and low air pollution levels in the study location.

Short-Term Effects of Carbonaceous Components in PM2.5 on Pulmonary Function: A Panel Study of 37 Chinese Healthy Adults

OBJECTIVES

To explore the health effects of indoor/outdoor carbonaceous compositions in PM_2.5 on pulmonary function among healthy students living in the local university campus.

METHODS

Daily peak expiratory flow (PEF) and forced expiratory volume in 1 second (FEV₁) were measured among 37 healthy students in the morning and evening for four two-week periods. Concurrent concentrations of indoor and outdoor PM_2.5 (particulate matter with an aerodynamic diameter ≤ 2.5μm), carbonaceous components in PM_2.5, ambient temperature, and relative humidity in the study area were also obtained. Mixed-effects model was applied to evaluate the associations between carbonaceous components and lung function. Different lags for the carbonaceous components were investigated.

RESULTS

In single-pollutant model, a 10 μg/m³ increase of indoor and outdoor EC (elemental carbon) associated with -3.93 (95%CI: -6.89, -0.97) L/min and -3.21 (95%CI: -5.67, -0.75) L/min change in evening PEF at lag 0 day, respectively. Also, a 10 μg/m³ increase of indoor and outdoor POC (primary organic carbon) concentration was significantly associated with -5.82 (95%CI: -10.82, -0.81) L/min and -7.32 (95%CI: -12.93, -1.71) L/min change of evening PEF at lag 0 day. After adjusting total mass of PM_2.5, indoor EC consistently had a significant adverse impact on evening PEF and FEV₁ at lag3 day and a cumulative effect at lag0-3 day.

CONCLUSIONS

This study suggests that carbonaceous components in PM_2.5 indeed have impacts on pulmonary function among healthy young adults especially on evening PEF. Thus, the local mitigation strategies on pollution are needed.

Exposure to ambient fine particles causes abnormal energy metabolism and ATP decrease in lung tissues

Airborne fine particles, generating from human activities, have drawn increasing attention due to their potential lung health hazards. The currently available toxicological data on fine particles is still not sufficient to explain their cause-and-effect. Based on well reported critical role of ATP on maintaining lung structure and function, the alterations of ATP production and energy metabolism in lungs of rats exposed to different dosages of seasonal PM_2.5 were investigated. Haze dosage PM_2.5 exposure was demonstrated to reduce the ATP production. Activity of critical enzymes in TCA cycle, such as malate dehydrogenase (MDH) and citrate synthase (CS), and expression of mitochondrial respiration chain genes were attenuated in groups exposed to haze dosage PM_2.5. In contrast, there was prominent augment of glycolytic markers at haze dosage PM_2.5, including metabolite contents (pyruvate and lactic acid), enzyme activities (hexokinase (HK) and pyruvate kinase (PKM)), along with mRNA levels of PKM and LDH. Consequently, sub-chronic exposure to seasonal haze PM_2.5 caused reduction in ATP generation and metabolic rewiring from TCA cycle to glycolysis. Our findings can help better understand the toxicological mechanism of lung disease caused by particulate air pollution.

Different health effects of indoor- and outdoor-originated PM2.5 on cardiopulmonary function in COPD patients and healthy elderly adults

Numerous research has explored the associations of outdoor or indoor fine particulate matter (PM_2.5 ) and health effects; however, few studies compared the effects of indoor PM_2.5 originated from outdoor (PM_2.5,os ) and indoor sources (PM_2.5,is ). To assess the associations of PM_2.5,os and PM_2.5,is with cardiopulmonary function in patients with chronic obstructive pulmonary disease (COPD) and healthy elderly adults, blood pressure (BP) and pulmonary function were repeatedly examined in 43 COPD patients and their 32 healthy spouses in Beijing, China. Iron was used as tracer element to separate PM_2.5,os and PM_2.5,is . Mixed-effects models were applied to assess the associations of PM_2.5,os or PM_2.5,is and health effects after controlling for potential confounders. There was a reduction in forced expiratory volume in first second (FEV₁ ) in COPD patients associated with PM_2.5,is during the heating season. PM_2.5,os was positively associated with diastolic BP (DBP) in healthy elderly adults during the heating season. There was a reduction in peak expiratory flow (PEF) in healthy elderly adults associated with PM_2.5,os during the non-heating season. Exposure to indoor- and outdoor-originated PM_2.5 had different health effects on cardiopulmonary function in different populations. The results provide supporting evidence for improving indoor air quality to promote public health among susceptible population.

The CD25+/CD4+ T cell ratio and levels of CII, CIX and CXI antibodies in serum may serve as biomarkers of pristane-induced arthritis in rats and Rheumatoid Arthritis in humans

OBJECTIVE

Collagen antibodies in serum are involved in the pathogenesis of Rheumatoid Arthritis (RA). The objective of this study was to identify the subtype of collagen antibodies and T cell subtype distribution in pristane-induced arthritis (PIA) and to clarify their roles in the initiation and maintenance of arthritis.

METHODS

Arthritis was induced in Dark Agouti (DA) rats by injection of pristane. The severity was evaluated by macroscopic and microscopic score systems. The alteration of CD25+/CD4+ T cell ratio in rats was detected by flow cytometry. Collagen type II (CII), CIX, or CXI antibody in serum was determined by ELISA. The levels of Nitric oxide (NO) and tartrate-resistant acid phosphatase (TRAP) were measured by kits.

RESULTS

The serum levels of CII, CIX, CXI antibodies were significantly increased in RA patients while slightly increased in PIA rats. The ratio of CD25+/CD4+ T cells was significantly higher in RA rats than that in the control group. The serum levels of NO and TRAP in PIA rats and RA patients were higher than that in the control groups, which suggested that the activity of osteoclast was increased in RA.

CONCLUSION

The ratio of CD25+/CD4+ T cells plays a pivotal role in the development of PIA. The serum levels of NO and TRAP are inflammatory and osteoclast activity indicators. The serum levels of CII, CIX and CXI antibodies may serve as the clinical diagnostic indicators. These findings are important to our understanding of the pathogenesis of RA, and may provide biomarkers of RA diagnosis and therapeutic targets for the treatment of RA.

Association of heavy metals with measures of pulmonary function in children and youth: Results from the National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION

Exposure to cadmium, cobalt, lead, and manganese has been associated with decreased pulmonary function in adults. Little is known about the magnitude of these associations among children in the United States.

OBJECTIVES

We evaluated cross-sectional associations of blood and urinary concentrations of cadmium, cobalt, lead, and manganese with pulmonary function measures [forced expiratory volume in one second (FEV1; milliliters), forced vital capacity (FVC; milliliters), ratio of FEV1 to FVC (FEV1:FVC), and mid-exhalation forced expiratory flow rate (FEF 25-75%; milliliters/second)] in a sample of 1234 6-17 year olds, who participated in the 2011-2012 survey cycle of the National Health and Nutrition Examination Survey (NHANES).

METHODS

Survey-weighted linear regression was used to estimate beta coefficients and 95% confidence intervals (CIs) for the associations between metal exposure tertiles or quartiles and pulmonary function test parameters, with adjustment for relevant covariates.

RESULTS

Blood manganese concentration was inversely associated with FVC (β for highest versus lowest quartile = -97.1, 95% CI = -230.6, 36.4; p for trend = 0.03). Urinary manganese was inversely associated with FEV1:FVC and FEF 25-75% (p for trend = 0.05 and 0.02, respectively). Urinary lead was inversely associated with FEF 25-75% (p for trend = 0.01). The associations between blood manganese and both FEV1 and FVC differed by age (p for interaction = 0.04 and 0.04, respectively), indicating an inverse trend that was strongest among older youth.

CONCLUSIONS

Environmental exposure to manganese and lead may adversely impact the pulmonary function of young people in the United States. Our findings highlight a need to prioritize children's environmental health and evaluate these associations prospectively.

Revisiting the Veterans Cohort Mortality Study: New results and synthesis

The Veterans Cohort Mortality Study began in 1999 in collaboration with Washington University in St. Louis, comprising ~70,000 male military veterans. We published six research papers on this cohort, considering the dynamics of all-cause mortality as the subjects aged and environmental parameters changed. This paper summarizes those results and presents new results by age group. Pollutants included monitored and modeled criteria pollutants, vehicular traffic density (annual km driven per unit of county land area), and modeled nationwide levels of hazardous species. In addition to spatial relationships, we examined the effects of exposure timing through separate analyses of sequential follow-up and exposure periods from 1976 to 2001. Risks associated with peak ozone decreased with lag between exposure and response, suggesting acute effects. Risks associated with traffic were invariant over time and consistent across five exposure databases. Associations with ozone were also coherent across databases; we found no consistent associations with particulate matter. Epidemiology considers both spatial and temporal relationships; most long-term studies focus on spatial gradients at a given time, thus masking effects of cohort aging and other trends during follow-up. Our new analyses distinguished between these temporal effects by analyzing age deciles for which separate mortality risks had been estimated for nationwide levels of nitrogen oxides (NO_x), benzene, and traffic density during four sequential follow-up subperiods, thus providing 40 sets of mortality risk coefficients. We used ordinary least squares regression to define relationships with subject age and follow-up year for the data set of 40 coefficients. We found strong nonlinear relationships between subject age and mortality coefficients for smoking, climate, poverty status, and air pollution; only smoking and climate coefficients changed over time as well. We concluded that these pollutant-mortality relationships reflected differences among the veterans' residential locations rather than changes in their pollution exposures during follow-up. We saw no evidence that cleaner air reduced mortality. Implications: Recent air pollution mortality studies emphasize PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm); we show associations with many other pollutants and a measure of traffic intensity. Control policies should thus be based on multipollutant analyses. We found no reduced risks with improved air quality after distinguishing cohort aging from purely temporal effects; longitudinal studies of accountability must thus account for changes in demography and exposures. Our studies of exposure timing indicate mainly coincident responses and no evidence for cumulative effects typical of smoking; we had no information on personal exposures. We found the strongest risks were associated with high-traffic locations rather than outdoor air quality per se.