Metals and oxidative potential in urban particulate matter influence systemic inflammatory and neural biomarkers: A controlled exposure study

Metal and oxidative potential exposure through particle inhalation and oxidative stress biomarkers: a 2-week pilot prospective study among Parisian subway workers

OBJECTIVE

In this pilot study on subway workers, we explored the relationships between particle exposure and oxidative stress biomarkers in exhaled breath condensate (EBC) and urine to identify the most relevant biomarkers for a large-scale study in this field.

METHODS

We constructed a comprehensive occupational exposure assessment among subway workers in three distinct jobs over 10 working days, measuring daily concentrations of particulate matter (PM), their metal content and oxidative potential (OP). Individual pre- and post-shift EBC and urine samples were collected daily. Three oxidative stress biomarkers were measured in these matrices: malondialdehyde (MDA), 8-hydroxy-2'deoxyguanosine (8-OHdG) and 8-isoprostane. The association between each effect biomarker and exposure variables was estimated by multivariable multilevel mixed-effect models with and without lag times.

RESULTS

The OP was positively associated with Fe and Mn, but not associated with any effect biomarkers. Concentration changes of effect biomarkers in EBC and urine were associated with transition metals in PM (Cu and Zn) and furthermore with specific metals in EBC (Ba, Co, Cr and Mn) and in urine (Ba, Cu, Co, Mo, Ni, Ti and Zn). The direction of these associations was both metal- and time-dependent. Associations between Cu or Zn and MDAEBC generally reached statistical significance after a delayed time of 12 or 24 h after exposure. Changes in metal concentrations in EBC and urine were associated with MDA and 8-OHdG concentrations the same day.

CONCLUSION

Associations between MDA in both EBC and urine gave opposite response for subway particles containing Zn versus Cu. This diverting Zn and Cu pattern was also observed for 8-OHdG and urinary concentrations of these two metals. Overall, MDA and 8-OHdG responses were sensitive for same-day metal exposures in both matrices. We recommend MDA and 8-OHdG in large field studies to account for oxidative stress originating from metals in inhaled particulate matter.

Disentangling fine particles (PM2.5) composition in Hanoi, Vietnam: Emission sources and oxidative potential

A comprehensive chemical characterization of fine particulate matter (PM2.5) was conducted at an urban site in one of the most densely populated cities of Vietnam, Hanoi. Chemical analysis of a series of 57 daily PM2.5 samples obtained in 2019-2020 included the quantification of a detailed set of chemical tracers as well as the oxidative potential (OP), which estimates the ability of PM to catalyze reactive oxygen species (ROS) generation in vivo as an initial step of health effects due to oxidative stress. The PM2.5 concentrations ranged from 8.3 to 148 μg m-3, with an annual average of 40.2 ± 26.3 μg m-3 (from September 2019 to December 2020). Our results obtained by applying the Positive Matrix Factorization (PMF) source-receptor apportionment model showed the contribution of nine PM2.5 sources. The main anthropogenic sources contributing to the PM mass concentrations were heavy fuel oil (HFO) combustion (25.3 %), biomass burning (20 %), primary traffic (7.6 %) and long-range transport aerosols (10.6 %). The OP activities were evaluated for the first time in an urban site in Vietnam. The average OPv levels obtained in our study were 3.9 ± 2.4 and 4.5 ± 3.2 nmol min-1 m-3 for OPDTT and OPAA, respectively. We assessed the contribution to OPDTT and OPAA of each PM2.5 source by applying multilinear regression models. It shows that the sources associated with human activities (HFO combustion, biomass burning and primary traffic) are the sources driving OP exposure, suggesting that they should be the first sources to be controlled in future mitigation strategies. This study gives for the first time an extensive and long-term chemical characterization of PM2.5, providing also a link between emission sources, ambient concentrations and exposure to air pollution at an urban site in Hanoi, Vietnam.

Toxic Potencies of Particulate Matter from Typical Industrial Plants Mediated with Acidity via Metal Dissolution

Acidity is an important property of particulate matter (PM) in the atmosphere, but its association with PM toxicity remains unclear. Here, this study quantitively reports the effect of the acidity level on PM toxicity via pH-control experiments and cellular analysis. Oxidative stress and cytotoxicity potencies of acidified PM samples at pH of 1-2 were up to 2.8-5.2 and 2.1-13.2 times higher than those at pH of 8-11, respectively. The toxic potencies of PM samples from real-world smoke plumes at the pH of 2.3 were 9.1-18.2 times greater than those at the pH of 5.6, demonstrating a trend similar to that of acidified PM samples. Furthermore, the impact of acidity on PM toxicity was manifested by promoting metal dissolution. The dramatic increase by 2-3 orders of magnitude in water-soluble metal content dominated the variation in PM toxicity. The significant correlation between sulfate, the pH value, water-soluble Fe, IC20, and EC1.5 (p < 0.05) suggested that acidic sulfate could enhance toxic potencies by dissolving insoluble metals. The findings uncover the superficial association between sulfate and adverse health outcomes in epidemiological research and highlight the control of wet smoke plume emissions to mitigate the toxicity effects of acidity.

Effect of PM2.5 exposure on adhesion molecules and systemic nitric oxide in healthy adults: The role of metals, PAHs, and oxidative potential

Since there is limited evidence on the impact of PM2.5 content on cardiovascular biomarkers, we conducted a cross-sectional study on 89 healthy adults from October 12 to November 21, 2021. We measured daily PM2.5 in two distinct regions during different time windows: a high-traffic urban area and an industrial suburb. The concentrations of metals, PAHs, and oxidative potential (OP) were determined using ICP-MS, GC-MS, and dithiothreitol (DTT), respectively. Systemic biomarkers, including NO, sICAM-1, sVCAM-1, MDA, and CRP, were quantified in each subject simultaneously. A generalized linear model was used to examine the association between PM2.5 toxicity and each health endpoint. Our findings indicated that daily PM2.5 concentrations exceeded the WHO-recommended level by approximately sevenfold. We found that PM2.5 exposure was associated with adverse cardiovascular outcomes. Moreover, exposure to PM2.5 mass, total PAHs, and certain trace metals (Ni, Fe, V, As, and Pb) resulted in a decline in serum NO levels. At lag 3, exposure to PM2.5 mass resulted in a significant decrease in NO levels [1.32% (95% CI: -2.27, -0.12)] and total PAHs [2.05% (95% CI: -3.93, -0.12)]. In contrast, OP exhibited a mild correlation with NO level increases. Positive associations were observed between PM2.5 and its chemical constituents (PAHs, As, Cu, OP) and adhesion molecules at different lag times. An increase of 0.16 ppb in PAH concentrations at an interquartile range was associated with a 4.74% decline (95% CI, -7.80, -0.55) in the sVCAM-1 level. However, our study did not reveal any significant trend between pollutants and other biomarkers (sICAM-1, MDA, and CRP). Consequently, our findings suggest that different PM2.5 chemical compositions exhibit diverse behavior in biological responses.

Multipollutant reciprocal neurological hazard from smoke particulate matter and heavy metals cadmium and lead in brain nerve terminals

Heavy metals, Cd2+ and Pb2+, and carbonaceous air pollution particulate matter are hazardous neurotoxicants. Here, a capability of water-suspended smoke particulate matter preparations obtained from poplar wood (WPs) and polypropylene fibers (medical facemasks) (MPs) to influence Cd2+/Pb2+-induced neurotoxicity, and vice versa, was monitored using biological system, i.e. isolated presynaptic rat cortex nerve terminals. Combined application of Pb2+ and WPs/MPs to nerve terminals in an acute manner revealed that smoke preparations did not change a Pb2+-induced increase in the extracellular levels of excitatory neurotransmitter L-[14C]glutamate and inhibitory one [3H]GABA, thereby demonstrating additive result and no interference of neurotoxic effects of Pb2+ and particulate matter. Whereas, both smoke preparations decreased a Cd2+-induced increase in the extracellular level of L-[14C]glutamate and [3H]GABA in nerve terminals. In fluorimetric measurements, the metals and smoke preparations demonstrated additive effects on the membrane potential of nerve terminals causing membrane depolarisation. WPs/MPs-induced reduction of spontaneous ROS generation was mitigated by Cd2+ and Pb2+. Therefore, a potential variety of multipollutant heavy metal-/airborne particulate-induced effects on key presynaptic processes was revealed. Multipollutant reciprocal neurological hazard through disturbance of the excitation-inhibition balance, membrane potential and ROS generation was evidenced. This multipollutant approach and data contribute to up-to-date environmental quality/health risk estimation.

The causal effect of air pollution on the risk of essential hypertension: a Mendelian randomization study

Background

Air pollution poses a major threat to human health by causing various illnesses, such as cardiovascular diseases. While plenty of research indicates a correlation between air pollution and hypertension, a definitive answer has yet to be found.

Methods

Our analyses were performed using the Genome-wide association study (GWAS) of exposure to air pollutants from UKB (PM2.5, PM10, NO2, and NOX; n = 423,796 to 456,380), essential hypertension from FinnGen (42,857 cases and 162,837 controls) and from UKB (54,358 cases and 408,652 controls) as a validated cohort. Univariable and multivariable Mendelian randomization (MR) were conducted to investigate the causal relationship between air pollutants and essential hypertension. Body mass index (BMI), alcohol intake frequency, and the number of cigarettes previously smoked daily were included in multivariable MRs (MVMRs) as potential mediators/confounders.

Results

Our findings suggested that higher levels of both PM2.5 (OR [95%CI] per 1 SD increase in predicted exposure = 1.24 [1.02-1.53], p = 3.46E-02 from Finn; OR [95%CI] = 1.04 [1.02-1.06], p = 7.58E-05 from UKB) and PM10 (OR [95%CI] = 1.24 [1.02-1.53], p = 3.46E-02 from Finn; OR [95%CI] = 1.04 [1.02-1.06], p = 7.58E-05 from UKB) were linked to an increased risk for essential hypertension. Even though we used MVMR to adjust for the impacts of smoking and drinking on the relationship between PM2.5 exposure and essential hypertension risks, our findings suggested that although there was a direct positive connection between them, it is not present after adjusting BMI (OR [95%CI] = 1.05 [0.87-1.27], p = 6.17E-01). Based on the study, higher exposure to PM2.5 and PM10 increases the chances of developing essential hypertension, and this influence could occur through mediation by BMI.

Conclusion

Exposure to both PM2.5 and PM10 is thought to have a causal relationship with essential hypertension. Those impacted by substantial levels of air pollution require more significant consideration for their cardiovascular health.

Effects of personal exposure to the oxidative potential of PM2.5 on oxidative stress biomarkers in pregnant women

Oxidative stress is a prominent pathway for the health effects associated with fine particulate matter (PM2.5) exposure. Oxidative potential (OP) of PM has been associated to several health endpoints, but studies on its impact on biomarkers of oxidative stress remains insufficient. 300 pregnant women from the SEPAGES cohort (France) carried personal PM2.5 samplers for a week and OP was measured using ascorbic acid (AA) and dithiothreitol (DTT) assays, and normalized by 1) PM2.5 mass (OPm) and 2) sampled air volume (OPv). A pool of three urine spots collected on the 7th day of PM sampling was analyzed for biomarkers, namely 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA) and 8-isoprostaglandin-F2α (8-isoPGF2α). Associations were investigated using adjusted multiple linear regressions. OP effects were additionally investigated by stratifying by median PM2.5 concentration (14 μg m-3). In the main models, no association was observed with 8-isoPGF2α, nor MDA. An interquartile range (IQR) increase in OPmAA exposure was associated with increased 8-OHdG (percent change: 6.2 %; 95 % CI: 0.2 % to 12.6 %). In the stratified analysis, exposure to OPmAA was associated with 8-OHdG for participants exposed to low levels of PM2.5 (percent change: 11.4 %; 95 % CI: 3.3 % to 20.1 %), but not for those exposed to high levels (percent change: -1.0 %; 95 % CI: -10.6 % to 9.6 %). Associations for OPmDTT also followed a similar pattern (p-values for OPmAA-PM and OPmDTT-PM interaction terms were 0.12 and 0.11, respectively). Overall, our findings suggest that OPmAA may be associated with increased DNA oxidative damage. This association was not observed with PM2.5 mass concentration exposure. The effects of OPmAA in 8-OHdG tended to be stronger at lower (below median) vs. higher concentrations of PM2.5. Further epidemiological, toxicological and aerosol research are needed to further investigate the OPmAA effects on 8-OHdG and the potential modifying effect of PM mass concentration on this association.

Exposure to ambient air pollutants is associated with an increased incidence of hyperuricemia: A longitudinal cohort study among Chinese government employees

BACKGROUND

It is widely recognized that ambient air pollution can induce various detrimental health outcomes. However, evidence linking ambient air pollutants and hyperuricemia incidence is scarce.

OBJECTIVES

To assess the association between long-term air pollution exposure and the risk of hyperuricemia.

METHODS

In this study, a total of 5854 government employees without hyperuricemia were recruited and followed up from January 2018 to June 2021 in Hunan Province, China. Hyperuricemia was defined as serum uric acid (SUA) level of >420 μmol/L for men and >360 μmol/L for women or use of SUA-lowering medication or diagnosed as hyperuricemia during follow-up. Data from local air quality monitoring stations were used to calculate individual exposure levels of PM10, PM2.5, SO2 and NO2 by inverse distance weightingn (IDW) method. Cox proportional hazard model was applied to evaluate the causal relationships between air pollutant exposures and the risk of hyperuricemia occurrence after adjustment for potential confounders and meanwhile, restricted cubic spline was used to explore the dose-response relationships.

RESULTS

The results indicated that exposures to PM10 (hazard ratio, HR = 1.042, 95% conficence interal, 95% CI: 1.028, 1.057), PM2.5 (HR = 1.204, 95% CI: 1.141, 1.271) and NO2 (HR = 1.178, 95% CI: 1.125,1.233) were associated with an increased HR of hyperuricemia. In addition, a nonlinear dose-response relationship was found between PM10 exposure level and the HR of hyperuricemia (p for nonlinearity = 0.158) with a potential threshold of 50.11 μg/m3. Subgroup analysis demonstrated that participants usually waking up at night and using natural ventilation were more vulnerable to the exposures of PM10, PM2.5, NO2, and SO2.

CONCLUSION

Long-term exposures to ambient PM10, PM2.5 and NO2 are associated with an increased incidence of hyperuricemia among Chinese government employees.

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.

Independent and combined associations of urinary metals exposure with markers of liver injury: Results from the NHANES 2013-2016

BACKGROUND

Heavy metals entering the human body could cause damage to a variety of organs. However, the combined harmful effects of exposure to various metals on liver function are not well understood. The purpose of the study was to investigate the independent and joint relationships between heavy metal exposure and liver function in adults.

METHODS

The study involved 3589 adults from the National Health and Nutrition Examination Survey. Concentrations of urinary metals, including arsenic (As), cadmium (Cd), lead (Pb), antimony (Sb), barium (Ba), thallium (Tl), tungsten (W), uranium (U), were determined in urine using inductively coupled plasma mass spectrometry. Data for liver function biomarkers included alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transaminase (GGT), and alkaline phosphatase (ALP). Survey-weighted linear regression and quantile g-computation (qgcomp) were employed to evaluate the relationship of urinary metals with the markers of liver injury.

RESULTS

Cd, U and Ba were found to have positive correlations with ALT, AST, GGT, and ALP in the survey-weighted linear regression analyses. According to the qgcomp analyses, the total metal mixture was positively correlated with ALT (percent change: 8.15; 95% CI: 3.84, 12.64), AST (percent change: 5.55; 95% CI: 2.39, 8.82), GGT (percent change: 14.30; 95% CI: 7.81, 21.18), and ALP (percent change: 5.59; 95% CI: 2.65, 8.62), and Cd, U, and Ba were the main contributors to the combined effects. Positive joint effects were observed between Cd and U on ALT, AST, GGT and ALP, and U and Ba had positive joint effects on ALT, AST and GGT.

CONCLUSION

Exposures to Cd, U, and Ba were individually associated with multiple markers of liver injury. Mixed metal exposure might be adversely correlated with markers of liver function. The findings indicated the potential harmful effect of metal exposure on liver function.

Personal exposure to PM2.5 oxidative potential and its association to birth outcomes

BACKGROUND

Prenatal exposure to fine particulate matter (PM2.5) assessed through its mass concentration has been associated with foetal growth restriction in studies based on outdoor levels. Oxidative potential of PM2.5 (OP) is an emerging metric a priori relevant to mechanisms of action of PM on health, with very limited evidence to indicate its role on birth outcomes.

OBJECTIVES

We investigated the association of OP with birth outcomes and compared it with that of PM2.5 mass concentration.

METHODS

405 pregnant women from SEPAGES cohort (Grenoble area) carried PM2.5 personal dosimeters for one or two one-week periods. OP was measured using dithiothreitol (DTT) and ascorbic acid (AA) assays from the collected filters. Associations of each exposure metric with offspring weight, height, and head circumference at birth were estimated adjusting for potential confounders.

RESULTS

The correlation between PM2.5 mass concentration and [Formula: see text] was 0.7. An interquartile range increase in .. was associated with reduced weight (adjusted change, -64 g, -166 to -11, p = 0.02) and height (-4 mm, -6 to -1, p = 0.01) at birth. PM2.5 mass concentration showed similar associations with weight (-53 g, -99 to -8, p = 0.02) and height (-2 mm, -5 to 0, p = 0.05). In birth height models mutually adjusted for the two exposure metrics, the association with [Formula: see text] was less attenuated than that with mass concentration, while for weight both effect sizes attenuated similarly. There was no clear evidence of associations with head circumference for any metric, nor for [Formula: see text] with any growth parameter.

IMPACT

PM2.5 pregnancy exposure assessed from personal dosimeters was associated with altered foetal growth. Personal OP exposure was associated with foetal growth restrictions, specifically decreased weight and height at birth, possibly to a larger extent than PM2.5 mass concentration alone. These results support OP assessed from DTT as being a health-relevant metric. Larger scale cohort studies are recommended to support our findings.

Seasonal variation of driving factors of ambient PM2.5 oxidative potential in Shenzhen, China

Reactive oxygen species (ROS) play a central role in health effects of ambient fine particulate matter (PM_2.5). In this work, we screened for efficient and complementary oxidative potential (OP) measurements by comparing the response values of multiple chemical probes (OP^DTT, OP^OH, OP^GSH) to ambient PM_2.5 in Shenzhen, China. Combined with meteorological condition and PM_2.5 chemical composition analysis, we explored the effects of different chemical components and emission sources on the ambient PM_2.5 OP and analyzed their seasonal variations. The results show that OP_m^DTT(mass-normalized) and OP_m^GSH-SLF were highly correlated (r = 0.77). OP^DTT was mainly influenced by organic carbon, while OP^OH was highly dominated by heavy metals. The combination of OP^DTT and OP^OH provides an efficient and comprehensive measurement of OP. Temporally, the OPs were substantially higher in winter than in summer (1.4 and 4 times higher for OP_m^DTT and OP_m^OH, respectively). The long-distance transported biomass burning sources from the north dominated the OP^DTT in winter, while the ship emissions mainly influenced the summer OP. The OP_m^DTT increased sharply with the decrease of PM_2.5 mass concentration, especially when the PM_2.5 concentration was lower than 30 μg/m³. The huge differences in wind fields between the winter and summer cause considerable variations in PM_2.5 concentrations, components, and OP. Our work emphasizes the necessity of long-term, multi-method, multi-component assessment of the OP of PM_2.5.

Unequal airborne exposure to toxic metals associated with race, ethnicity, and segregation in the USA

Persons of color have been exposed to a disproportionate burden of air pollution across the United States for decades. Yet, the inequality in exposure to known toxic elements of air pollution is unclear. Here, we find that populations living in racially segregated communities are exposed to a form of fine particulate matter with over three times higher mass proportions of known toxic and carcinogenic metals. While concentrations of total fine particulate matter are two times higher in racially segregated communities, concentrations of metals from anthropogenic sources are nearly ten times higher. Populations living in racially segregated communities have been disproportionately exposed to these environmental stressors throughout the past decade. We find evidence, however, that these disproportionate exposures may be abated though targeted regulatory action. For example, recent regulations on marine fuel oil not only reduced vanadium concentrations in coastal cities, but also sharply lessened differences in vanadium exposure by segregation.

Exposure to metal mixtures and hypertensive disorders of pregnancy: A nested case-control study in China

Exposure to metals has been linked with the risk of hypertensive disorders of pregnancy (HDP), but little is known about the potential effects of exposure to metal mixtures. Thus, our study aimed to investigated the impact of a complex mixture of metals on HDP, especially the interactions among metal mixtures. We did a population-based nested case-control study from October 2013 to October 2016 in Wuhan, China, including 146 HDP cases and 292 controls. Plasma concentrations of Aluminum (Al), Barium (Ba), Cobalt (Co), Copper (Cu), Lead (Pb), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Strontium (Sr), Thallium (Tl), and Vanadium (V) were measured and collected between 10 and 16 gestational weeks. We employed quantile g-computation, conditional logistic regression models, and Bayesian Kernel Machine Regression (BKMR) to assess the association of individual metals and metal mixtures with HDP risk. In the quantile g-computation, the OR for a joint tertile increase in plasma concentrations was 3.67 (95% CI: 1.70, 7.91). Hg contributed the largest positive weights and followed by Al, Ni, and V. In conditional logistic regression models, concentrations of Hg, Al, Ni, and V were significantly associated with the risk of HDP (p-FDR < 0.05). Compared to the lowest tertiles, the ORs (95% CI) for the highest tertiles of these four metals were 2.67 (1.44, 4.95), 3.09 (1.70, 5.64), 5.31 (2.68, 10.53), and 4.52 (2.26, 9.01), respectively. In the BKMR analysis, we observed a linear positive association between Hg, Al, V, and HDP, and a nonlinear relationship between Ni and HDP. A potential interaction between Al and V was also identified. We found that exposure to metal mixtures in early pregnancy, both individually and as a mixture, was associated with the risk of HDP. Potential interaction effects of Al and V on the risk of HDP may exist.

Characterization of fetal exposure to multiple metals among an urban population: A case study of New York City

INTRODUCTION

Metals and metalloids are ubiquitous and persistent in urban areas and are generally released into the environment as mixtures.

OBJECTIVES

The purpose of this study was to establish baseline concentrations of selected elements in meconium samples among a large urban population in the US and understand the spatial variability in concentrations. The association of metal mixtures on birth weight was also assessed.

METHODS

This cross-sectional study was conducted across five public hospitals located in New York City, NY (NYC) in four boroughs. We collected meconium sample from 116 infants during the first 24 h after delivery and quantified 11 metals using ICP-MS. Principal component analysis was used to determine metal mixtures and their association with birth weight. Spatial hot spots of each metal were calculated using the Getis-Ord (GI*).

RESULTS

Essential elements were detected in all samples with Zn in the greatest abundance (median = 274.5 μg/g) and Mo in the least (median = 0.1845 μg/g). Pb was detected in all but two samples (median = 0.0222 μg/g), while Cd levels were detected in approximately half of the samples (median = 0.0019 μg/g). Co-located hot spots were detected for Cu, Zn, and Fe in southeast Brooklyn; Cd, Cr, and Ni in eastern Queens; and Al and Mo in south Queens. There was a significant inverse relationship between Pb concentrations (beta = -1935.7; p = 0.006) and the mixture of Cr, Cu, Mo, Zn (beta = -157.7; p = 0.045) and birth weight.

CONCLUSIONS

Our findings indicate that meconium is an effective biomarker for measuring metal exposures among an urban population. We were able to quantify detectable levels of ten of the eleven metals measured in the study and characterize nutritionally necessary trace elements and metals derived from anthropogenic sources without biologic need in a cohort of NYC newborns. Further research needs to establish the change point from necessary to toxic, for the essential elements.

Identification of Legacy and Active Sources of Metal Contamination in Soils in Brooklyn, NY

The purpose of this study was to examine the spatial distribution and potential anthropogenic sources of lead (Pb), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) in surface soils throughout Brooklyn, NY. We collected soil samples (n = 1,373) from 176 different New York City parks. Samples were analyzed ex-situ using a portable X-ray fluorescence with a subset of samples laboratory confirmed. The effect of multiple sources on concentrations were determined by multivariable linear regression with generalized estimating equations. Median concentrations of Pb, Zn, Cu, Fe, and Mn were 108 ppm, 145 ppm, 49 ppm, 14,034 ppm, and 279 ppm, respectively. All metals were significantly correlated with one another (p < 0.001), with the strength of the correlation ranging from a low of approximately ρ = 0.3 (Pb-Mn and Zn-Mn) to a high of ρ = 0.7 (Pb-Cu). In final multivariate modeling significant association were observed between scrap yards and Mn concentration (β = 0.075, 0.019), National Priorities List (NPL) sites and Pb, Fe and Mn (β = 0.134, p = 0.004; β = 0.038, p = 0.014; β = 0.057, p = 0.037, respectively), and bridges nearby and Pb and Zn (β = 0.106, p = 0.003; β = 0.076, p = 0.026, respectively). Although manufacturing and industry have mostly left the area, smaller scrap metal recyclers are abundant and associated with increased Cu and Mn soil concentrations. In addition, NPL sites contributed to increased concentrations of all five metals within 800 m. Roadways have long been established to be sources of urban pollution; however, in our study we also found the presence of bridges within 800 m were also strongly predictive of increased Pb, Cu, and Zn concentrations.

Associations of Short-Term Exposure to Fine Particulate Matter with Neural Damage Biomarkers: A Panel Study of Healthy Retired Adults

Exposure to fine particulate matter (PM_2.5) is associated with various adverse health effects, such as respiratory and cardiovascular diseases. This study aimed to evaluate the association of PM_2.5 with neural damage biomarkers. A total of 34 healthy retirees were recruited from Xinxiang Medical University from December 2018 to April 2019. Concentrations of PM_2.5 constituents including 24 metals and nonmetallic elements and 6 ions, and 5 biomarkers of neural damage including brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), and S100 calcium-binding protein B (S100B) in serum were measured. A linear mixed-effect model was employed to estimate the association of PM_2.5 and its constituents with neural damage biomarkers. Modification effects of glutathione S-transferase theta 1 gene (GSTT1) polymorphism, sex, education, and physical activity on PM_2.5 exposure with neural damage were explored. PM_2.5 and its key constituents were significantly associated with neural damage biomarkers. A 10 μg/m³ increase in PM_2.5 concentration was associated with 2.09% (95% CI, 39.3-76.5%), 100% (95% CI, 1.73-198%), and 122% (95% CI, 20.7-222%) increments in BDNF, NfL, and PGP9.5, respectively. Several constituents such as Cu, Zn, Ni, Mn, Sn, V, Rb, Pb, Al, Be, Cs, Co, Th, U, Cl^-, and F^- were significantly associated with NfL. The estimated association of PM_2.5 with NSE in GSTT1-sufficient volunteers was significantly higher than that in GSTT1-null volunteers. Therefore, short-term PM_2.5 exposure was associated with neural damage, and GSTT1 expression levels modified the PM_2.5-induced adverse neural effects.

Do urinary metals associate with the homeostasis of inflammatory mediators? Results from the perspective of inflammatory signaling in middle-aged and older adults

OBJECTIVE

We aimed to investigate whether urinary metal mixtures are associated with the homeostasis of inflammatory mediators in middle-aged and older adults.

METHODS

A four-visit repeated-measures study was conducted with 98 middle-aged and older adults from five communities in Beijing, China. Only one person was lost to follow-up at the third visit. Ultimately, 391 observations were included in the analysis. The urinary concentrations of 10 metals were measured at each visit using inductively coupled plasma mass spectrometry (ICP-MS) with a limit of detection (LOD) ranging from 0.002 to 0.173 µg/L, and the detection rates were all above 84%. Similarly, 14 serum inflammatory mediators were measured using a Beckman Coulter analyzer and the Bio-Plex MAGPIX system. A linear mixed model (LMM), LMM with least absolute shrinkage and selection operator regularization (LMMLASSO), and Bayesian kernel machine regression (BKMR) were adopted to explore the effects of urinary metal mixtures on inflammatory mediators.

RESULTS

In LMM, a two-fold increase in urinary cesium (Cs) and chromium (Cr) was statistically associated with -35.22% (95% confidence interval [CI]: -53.17, -10.40) changes in interleukin 6 (IL-6) and -11.13% (95 %CI: -20.67, -0.44) in IL-8. Urinary copper (Cu) and selenium (Se) was statistically associated with IL-6 (88.10%, 95%CI: 34.92, 162.24) and tumor necrosis factor-alpha (TNF-α) (22.32%, 95%CI: 3.28, 44.12), respectively. Similar results were observed for the LMMLASSO and BKMR. Furthermore, Cr, Cs, Cu, and Se were significantly associated with other inflammatory regulatory network mediators. For example, urinary Cs was statistically associated with endothelin-1, and Cr was statistically associated with endothelin-1 and intercellular adhesion molecule 1 (ICAM-1). Finally, the interaction effects of Cu with various metals on inflammatory mediators were observed.

CONCLUSION

Our findings suggest that Cr, Cs, Cu, and Se may disrupt the homeostasis of inflammatory mediators, providing insight into the potential pathophysiological mechanisms of metal mixtures and chronic diseases.

The distribution and structural fingerprints of metals from particulate matters (PM) deposited in human lungs

This work investigated the distribution and chemical fingerprints of 24 metals in particulate matter (PM) deposited in nonoccupational human lungs. Metals in the pulmonary PM can be grouped by the mean concentration as > 5 × 10³ μg/g (Al/Fe/Ca/Mg/Zn), 1-5 × 10³ μg/g (Ti/Ba/Pb/Mn), 0.2-1 × 10³ μg/g (Cu/Cr/As/V) and < 100 μg/g (Ni/Sn/Cd/Sb). Three parameters (LF_L, LR, EF_P) were defined to predict different metal leaching behaviors. The leaching factor (LF_L) of metals was 10-60 for Pb/Sb/Cd/Co/Cu and decreased to 1-2 for Ni/Cr/Mg/Al/Fe. Metals showed a divergent extent of lung retention (LR), including high retention (LR>10, Al/Cd/Cr/Ba/Ni/Ti/Sn/V/Sb), moderate retention (2 <LR<10, Pb/Mn/Fe), minor retention (1 < LR <2, Cu/Co), and negligible retention (LR<1, Ca/Mg/Zn). V and Ti were found to be mainly from indoor PM sources and deserve a close attention in healthy individuals. C-, Al- and Ti-rich fine particles were the most common pulmonary particles imaged by spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM). These data establish a foundation for classification and further risk assessment of the metal species in pulmonary PM.

Acute responses of airway oxidative stress, inflammation, and hemodynamic markers to ambient PM2.5 and their trace metal contents among healthy adolescences: A panel study in highly polluted versus low polluted regions

Particulate air pollutants are known contributors to global cardiorespiratory mortality through several pathways. We examined the effects of varied exposure to PM_2.5 and trace metals on biological markers of airway inflammation, oxidative stress, and hemodynamic function of young individuals living in two different exposure settings. We enrolled and followed a panel of 97 healthy nonsmoking participants aged 15-18 years living in a highly polluted metropolitan city of Tabriz (TBZ) and a much less polluted semi-urban town of Hadishahr (HDS). For five consecutive months, the subjects were examined by a physician, and fractional exhaled nitric oxide levels (FE_NO) were measured. Samples of exhaled breath condensation (EBC) were obtained for measuring interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and total nitric oxide (NO_x). We measured daily outdoor PM_2.5 mass concentration in a fixed station in each location for all this period. The PM-metal content was analyzed by ICP-MS. The linear mixed-effects regression models were applied for data analysis. The averages of PM_2.5 mass and total metals in TBZ were nearly two and four times higher than in HDS, respectively. In TBZ, an increased IQR of PM_2.5 mass during 0-5 days was -correlated with a significant rise in diastolic blood pressure, heart rate, TNF-α, FE_NO, and NO_x and reduction of IL-6. Moreover, exposure to low PM_2.5 concentration is significantly -correlated with an elevation in diastolic blood pressure in HDS. We also observed that exposure to metal constituents in the highly polluted region is correlated with increased TNF-α and IL-6 with 131.80% (95% CI: 56.01, 244.39) and 47.51% (95% CI: 33.01, 62.05) per IQR of Hg, respectively. This study suggests that exposure to ambient PM_2.5 and their metal contents in highly polluted areas may incite significant changes in airway inflammation, oxidative stress, and hemodynamic parameters in healthy subjects.

Systemic inflammation mediates the association of heavy metal exposures with liver injury: A study in general Chinese urban adults

Heavy metal exposures have been reported to be associated with increased risk for liver injury. However, the potential mechanisms of the association remain unclear. A repeated-measure study of 9367 observations was conducted to quantify the associations of urinary heavy metals with serum alanine aminotransferase (ALT), a biomarker for liver injury, and assess the mediating role of systemic inflammation in such associations among general Chinese adults. In single-metal models, positive dose-response relationships between urinary vanadium (V), chromium (Cr), copper (Cu), arsenic (As), cadmium (Cd), tungsten (W), and lead (Pb) and serum ALT were observed. In the multiple-metal model containing the seven metals mentioned above, V and Cu remained positively associated with ALT. In longitudinal analyses of 3-6 years, each 1-unit increase in log-transformed levels of V and Cu was associated with an additional rate of annual ALT increase (95% CI) for 1.3% (0.7-1.8%) and 1.3% (0.7-2.0%), respectively. Plasma CRP concentrations were not only positively associated with urinary Cu and Cd, but also positively related with ALT. Furthermore, mediation analyses showed that CRP mediated 4.70% and 7.03% of urinary Cu- and Cd-associated ALT elevations. Our study provides clues for the prevention of heavy metal-induced liver injury.

Association between long-term exposure to fine particulate matter and diabetic retinopathy among diabetic patients: A national cross-sectional study in China

BACKGROUND

While the relationship between ambient air pollution and diabetes mellitus has recently been reported, data on the association between fine particulate matter (PM_2.5) and diabetic complications are limited, especially in microvascular diseases such as diabetic retinopathy.

OBJECTIVES

To investigate the associations between long-term exposure to PM_2.5 and the prevalence of diabetic retinopathy in adult diabetic patients in rural China.

METHODS

The study population was based on the Rural Epidemiology for Glaucoma in China (REG-China), a national cross-sectional survey conducted in rural China. This analysis selected diabetic patients with or without diabetic retinopathy. A satellite-based spatiotemporal model was used to estimate personal PM_2.5 exposure. Logistic regression models were used to investigate the effect of long-term PM_2.5 exposure on diabetic retinopathy.

RESULTS

The analysis included 3111 diabetic participants, 329 of whom were diagnosed with diabetic retinopathy. The median level of exposure to PM_2.5 from 2000 to2016 was 59.9 μg/m³. For each 10 μg/m³ increase in PM_2.5, the adjusted odds ratio (95% confidence interval) for diabetic retinopathy was 1.41 (1.27, 1.57). In subgroup analyses, the effect of PM_2.5 on diabetic retinopathy was significantly stronger in participants who self-reported alcohol consumption.

CONCLUSION

These findings suggest that long-term exposure to high PM_2.5 was associated with the risk of diabetic retinopathy among diabetic patients in rural China.

Independent and combined associations of urinary heavy metals exposure and serum sex hormones among adults in NHANES 2013-2016

Accumulating evidences indicated that heavy metals may disrupt human sex hormones. However, the combined effects of heavy metals on sex hormones remain to be clarified. To explore the independent and combined associations between heavy metal exposure and serum sex hormones among adults, data of 2728 adults from the National Health and Nutrition Examination Survey (NHANES) was applied. We examined independent and combined associations of fourteen urinary heavy metals and three serum sex steroid hormones (total testosterone (TT), estradiol (E2) and sex hormone-binding globulin (SHBG)). Multivariate linear regression was used to evaluate the independent associations between metal exposure and sex hormone alterations. Principle component analysis -weighted quantile sum regression (PCA-WQSR) model was performed to estimate the combined associations in our individuals. In the co-exposure model, we determined that weighted quantile sum (WQS) index of industrial pollutants was negatively associated with E2 in females (WQS Percent change_8-metal = -20.6%; 95% CI: -30.1%, -9.96%), while in males WQS index of water pollutants was negatively related to SHBG (WQS Percent change_8-metal = -5.35%; 95% CI: -9.88%, -0.598%). Cadmium (Cd), tin (Sn) and lead (Pb) were the dominating metals of female E2-negative association while Ba was the leading contributor related to male SHBG reduction, which was consistent with the results of multivariate linear regression. Additionally, in postmenopausal women, the associations of E2 decrease with heavy metal co-exposure remained significant while Cd and monomethylarsonic acid (MMA) were identified as hazardous metals in the mixture. We concluded that the exposure to heavy metals was associated with human sex hormone alterations in independent or combined manners. Considering the design of NHANES study, further studies from other national-representative surveys are necessary.

Particulate matter air pollutants and cardiovascular disease: Strategies for intervention

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and CVD-related mortality. Particulate matter (PM) is a critical factor in air pollution-associated CVD. PM forms in the air during the combustion of fuels as solid particles and liquid droplets and the sources of airborne PM range from dust and dirt to soot and smoke. The health impacts of PM inhalation are well documented. In the US, where CVD is already the leading cause of death, it is estimated that PM2.5 (PM < 2.5 μm in size) is responsible for nearly 200,000 premature deaths annually. Despite the public health data, definitive mechanisms underlying PM-associated CVD are elusive. However, evidence to-date implicates mechanisms involving oxidative stress, inflammation, metabolic dysfunction and dyslipidemia, contributing to vascular dysfunction and atherosclerosis, along with autonomic dysfunction and hypertension. For the benefit of susceptible individuals and individuals who live in areas where PM levels exceed the National Ambient Air Quality Standard, interventional strategies for mitigating PM-associated CVD are necessary. This review will highlight current state of knowledge with respect to mechanisms for PM-dependent CVD. Based upon these mechanisms, strategies for intervention will be outlined. Citing data from animal models and human subjects, these highlighted strategies include: 1) antioxidants, such as vitamins E and C, carnosine, sulforaphane and resveratrol, to reduce oxidative stress and systemic inflammation; 2) omega-3 fatty acids, to inhibit inflammation and autonomic dysfunction; 3) statins, to decrease cholesterol accumulation and inflammation; 4) melatonin, to regulate the immune-pineal axis and 5) metformin, to address PM-associated metabolic dysfunction. Each of these will be discussed with respect to its potential role in limiting PM-associated CVD.

Insomnia associated with traffic noise and proximity to traffic-a cross-sectional study of the Respiratory Health in Northern Europe III population

STUDY OBJECTIVES

Exposure to traffic noise increases the risk of sleeping disturbance, but little is known about the effect of traffic-related air pollution on insomnia symptoms. We aimed to investigate the separate associations of self-reported proximity to traffic and traffic noise with insomnia.

METHODS

This is a cross-sectional study of the population included in the Respiratory Health in Northern Europe study, consisting of randomly selected men and women born between 1945 and 1973, from 7 Northern European centers. Hearing traffic noise in the bedroom, bedroom window proximity to traffic, and insomnia symptoms were self-reported. Bedroom window proximity to traffic was used as a surrogate for exposure to traffic-related air pollution. The following insomnia symptoms were assessed: difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening.

RESULTS

A total of 12,963 individuals was included. Traffic noise was positively associated with all three insomnia symptoms: difficulty initiating sleep (odds ratio [OR] = 3.54; 95% confidence interval [CI]: 1.85, 6.76), difficulty maintaining sleep (OR = 2.95; 95% CI: 1.62, 5.37), and early morning awakening (OR = 3.25; 95% CI: 1.97, 5.37). Proximity to traffic without disturbing noise was associated with difficulty initiating sleep (OR = 1.62; 95% CI: 1.45, 1.82).

CONCLUSIONS

This study adds further support to the identification of traffic noise as a risk factor for insomnia. Proximity to traffic without being exposed to noise was associated with an increased risk of difficulty initiating sleep. Our findings indicate that insomnia may be associated with both traffic noise and traffic-related air pollution.

Differential inflammatory and toxic effects in-vitro of wood smoke and traffic-related particulate matter from Sydney, Australia

BACKGROUND

It is well known that PM_2.5 generated by traffic or burning wood is pro-inflammatory and induces various adverse health outcomes in humans. In Sydney, New South Wales, Australia, the main anthropogenic contributors to particulate matter (PM) air pollution are wood combustion heaters, on-road vehicles, and coal-fired power stations. However, the relative toxicity of these local sources has not to date been investigated.

METHOD

PM_2.5 was collected on filters from the same sampling site in Liverpool, one suburb of Sydney. According to the positive matrix factorisation and collection season, filters were representative of either day with high traffic-related air pollution (TRAP), wood smoke, or both TRAP and woodsmoke (mixed air pollution). The elemental composition of the PM was assessed by accelerator-based ion beam analysis techniques (i.e. PIXE & PIGE) and size by Dynamic Light Scattering. Toxicity and inflammation were assessed in-vitro in human bronchial epithelial cells by measuring interleukin-6 (IL-6), interleukin-8 (IL-8) release, and MTT.

RESULTS

Mixed air pollution (TRAP/wood smoke) PM had more nanometer (nm) sized PM than the other two groups. Using an in-vitro model of the lungs, the mixed air pollution PM was the most toxic, whereas the PM from woodsmoke induced greater IL-6 release than TRAP PM. There was no difference in the induction of IL-8 between the three sources of PM.

CONCLUSION

Marked differences occur in the cellular response to PM from different sources, with differences in both toxicity and inflammation.

Particulate Matter and Associated Metals: A Link with Neurotoxicity and Mental Health

Particulate air pollution (PM) is a mixture of heterogenous components from natural and anthropogenic sources and contributes to a variety of serious illnesses, including neurological and behavioral effects, as well as millions of premature deaths. Ultrafine (PM0.1) and fine-size ambient particles (PM2.5) can enter the circulatory system and cross the blood–brain barrier or enter through the optic nerve, and then upregulate inflammatory markers and increase reactive oxygen species (ROS) in the brain. Toxic and neurotoxic metals such as manganese (Mn), zinc (Zn), lead (Pb), copper (Cu), nickel (Ni), and barium (Ba) can adsorb to the PM surface and potentially contribute to the neurotoxic effects associated with PM exposure. Epidemiological studies have shown a negative relationship between exposure to PM-associated Mn and neurodevelopment amongst children, as well as impaired dexterity in the elderly. Inhaled PM-associated Cu has also been shown to impair motor performance and alter basal ganglia in schoolchildren. This paper provides a brief review of the epidemiological and toxicological studies published over the last five years concerning inhaled PM, PM-relevant metals, neurobiology, and mental health outcomes. Given the growing interest in mental health and the fact that 91% of the world’s population is considered to be exposed to unhealthy air, more research on PM and PM-associated metals and neurological health is needed for future policy decisions and strategic interventions to prevent public harm.

Association of long-term exposure to ambient air pollution with the incidence of sleep disorders: A cohort study in China

BACKGROUND

Sleep disorders have been verified to be associated with adverse health outcomes. Recent studies have linked ambient air pollution to sleep disorders. However, evidence with large sample size and especially prospective studies is very limited.

METHODS

We used data from a prospective cohort study established from 2015 to 2018 in Ningbo, China. Participants were followed-up after baseline survey through linkage to the regional Health Information System (HIS). Sleep disorders were defined based on International Classification of Disease 10 (ICD-10). Spatial-temporal land-use regression (LUR) models were used to estimate the annual exposure to particulate matter with diameter ≤ 2.5 µm (PM_2.5), ≤ 10 µm (PM₁₀) and nitrogen dioxides (NO₂). The associations between long-term exposure to air pollutants and prevalence of sleep disorders were examined using logistic regression models, and Cox regression models for the effects of air pollution on the incidence of sleep disorders. A generalized weighted quantile sum (gWQS) regression was used in the multipollutant analysis.

RESULTS

A total of 38,775 participants were included in the final analysis. Based on baseline data, we observed significant positive associations between air pollution exposure and increased odds of prevalent sleep disorders (Odds Ratio (OR)= 1.48, 95% confidence interval (CI): 1.41-1.55 for PM_2.5; OR= 1.47,95%CI:1.38-1.57 for PM₁₀; OR= 1.38, 95%CI:1.31-1.46 for NO₂). In the longitudinal analysis, hazard ratios for incident sleep disorders associated with per interquartile range (IQR) increase in PM_2.5, PM₁₀ and NO₂ were 1.14 (1.03, 1.25), 1.13 (1.01, 1.27) and 1.13 (1.04, 1.23), respectively. A gWQS regression analysis showed significant association between air pollution mixture and incident sleep disorders (OR=1.11, 95%CI: 1.03-1.20).

CONCLUSIONS

Long-term exposure to PM_2.5, PM₁₀ and NO₂ were associated with increased risk of sleep disorders in a Chinese population. Our findings could provide evidence for a more general role in the adverse health impact of air pollution.

Mechanistic Insights into the Role of Iron, Copper, and Carbonaceous Component on the Oxidative Potential of Ultrafine Particulate Matter

Transition metals play a key role in the pathogenic potential of urban particulate matter (PM). However, air quality regulations include exposure limits only for metals having a known toxic potential like Pb, As, Cd, and Ni, neglecting other transition metals like Fe and Cu. Fe and Cu are mainly found in the water-soluble fraction of PM. However, a fraction of the ions may persist strongly bound to the particles, thus potentially acting as surface reactive sites. The contribution of surface ions to the oxidative potential (OP) of PM is likely different from that of free ions since the redox activity of metals is modulated by their local chemical environment. The aim of this study was to investigate how Fe and Cu bound to carbonaceous particles affect the OP and associated toxicity of PM toward epithelial cells and macrophages. Carbonaceous nanoparticles (CNPs) having well-defined size were loaded with controlled amounts of Cu and Fe. The effect of Cu and Fe on the OP of CNPs was evaluated by electronic paramagnetic resonance (EPR) spectroscopy associated with the spin-trapping technique and correlated with the ability to induce cytotoxicity (LDH, WST-1), oxidative stress (Nrf2 translocation), and DNA damage (comet assay) on lung macrophages (NR8383) and/or epithelial cells (RLE-6TN). The release of pro-inflammatory cytokines (TNF-α, MCP-1, and CXCL2) by macrophages and epithelial cells was also investigated. The results indicate a major contribution of surface Cu to the surface reactivity of CNPs, while Fe has a minor role. At the same time, Cu increases the cytotoxicity of CNPs and their ability to induce oxidative stress and DNA damage. In contrast, surface Fe increases the release of pro-inflammatory cytokines by macrophages. Overall, these results confirm the role of Cu and Fe in PM toxicity and suggest that the total metals content in PM might be a better indicator of pathogenicity than water-soluble metals.

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.

Neuropathology changed by 3- and 6-months low-level PM2.5 inhalation exposure in spontaneously hypertensive rats

Background

Epidemiological evidence has linked fine particulate matter (PM_2.5) to neurodegenerative diseases; however, the toxicological evidence remains unclear. The objective of this study was to investigate the effects of PM_2.5 on neuropathophysiology in a hypertensive animal model. We examined behavioral alterations (Morris water maze), lipid peroxidation (malondialdehyde (MDA)), tau and autophagy expressions, neuron death, and caspase-3 levels after 3 and 6 months of whole-body exposure to urban PM_2.5 in spontaneously hypertensive (SH) rats.

Results

SH rats were exposed to S-, K-, Si-, and Fe-dominated PM_2.5 at 8.6 ± 2.5 and 10.8 ± 3.8 μg/m³ for 3 and 6 months, respectively. We observed no significant alterations in the escape latency, distance moved, mean area crossing, mean time spent, or mean swimming velocity after PM_2.5 exposure. Notably, levels of MDA had significantly increased in the olfactory bulb, hippocampus, and cortex after 6 months of PM_2.5 exposure (p < 0.05). We observed that 3 months of exposure to PM_2.5 caused significantly higher expressions of t-tau and p-tau in the olfactory bulb (p < 0.05) but not in other brain regions. Beclin 1 was overexpressed in the hippocampus with 3 months of PM_2.5 exposure, but significantly decreased in the cortex with 6 months exposure to PM_2.5. Neuron numbers had decreased with caspase-3 activation in the cerebellum, hippocampus, and cortex after 6 months of PM_2.5 exposure.

Conclusions

Chronic exposure to low-level PM_2.5 could accelerate the development of neurodegenerative pathologies in subjects with hypertension.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-020-00388-6.

Circulating metal concentrations, inflammatory cytokines and gestational weight gain: Shanghai MCPC cohort

OBJECTIVES

Based on a prospective birth cohort, we aimed to investigate the associations between maternal circulating metals exposure and gestational weight gain (GWG) across pregnancy, and explore whether maternal inflammatory cytokines could contribute to the GWG changes associated with metals exposure.

METHODS

A total of 234 pregnant women from the Shanghai Maternal-Child Pairs cohort were enrolled in this panel study. 547 blood and serum samples were collected from pregnant women during three follow-up visits, and the circulating concentrations of 27 metals were determined by using the ICP-MS method. Five inflammatory cytokines in serum samples were measured through multiplexed immunoassays. The linear mixed models were used to estimate the association between each ln-transformed metal concentration and GWG across pregnancy. Robust generalized linear regression models were used to estimate the associations among circulating metals, GWG, and inflammatory cytokines.

RESULTS

The GWG during pregnancy was 13.76 ± 1.40 kg. The concentrations Co, Zn, Mo, B, Ag and Te in second or third trimesters were significantly higher than those in early second trimester. The concentration of Mg decreased with the increase of pregnant weeks and no significant statistical differences were found in the concentrations of other metals in different trimesters. Among the detected 26 metals, Li and Sr concentrations were positively associated with GWG in the third trimester. The GWG increased by 0.100 kg (95% CI 0.005, 0.195) and 0.120 kg (95% CI 0.009, 0.232) with each one ln-concentration increase in circulating Li and Sr concentrations, respectively. Concentrations of Li and Sr in the third trimester were positively associated with tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6, but negatively associated with growth differentiation factor-15 (GDF-15) significantly. Besides, IL-6 and GDF-15 levels were associated with the increase or decrease of overall pregnancy GWG, respectively.

CONCLUSIONS

Results showed that maternal exposure to Li and Sr were associated with increased GWG, in which maternal IL-6 and GDF-15 could contribute to the associations between metal exposures and GWG in pregnant women.

Toxicity and mechanism of mesoporous silica nanoparticles in eyes

The study on the safety of nanomaterials in eyes is still in its early stages. In this study, we put our focus on the effect of one important nanoparticle feature - large surface area - to assess eye safety. To this end, mesoporous silica nanoparticles (MSiNPs) were for the first time employed as a model to evaluate their toxicity in eyes. The porosity of the MSiNPs endows them with a large surface area and the ability to attach to surrounding chemical or biological molecules, further enhancing their surface reactivity and toxic effects. Therefore, to better mimic MSiNP exposure in real environments, we also introduced other hazardous substances such as silver ions (Ag+) to the system and then investigated their synergistic nanotoxicity. Our results showed that the exposure to MSiNPs-Ag+ and even Ag+ at a safe dose, resulted in more significant toxicity than the MSiNPs alone, as evidenced from cell viability, apoptosis, reactive oxygen species (ROS) production, and DNA damage experiments. RNA-Sequencing analysis revealed that the mRNA surveillance signalling pathway plays a unique role in regulating MSiNPs-Ag+-induced cytotoxicity. Besides this, severe corneal damage and dry eye were observed in rat models upon exposure to MSiNPs-Ag+ compared to MSiNPs. Most importantly, we also proposed a protein corona-based therapy to treat MSiNP-induced corneal disease, where the corneal damage could be rescued by fetal bovine serum (FBS) treatment.

Cardiovascular adaptations to particle inhalation exposure: molecular mechanisms of the toxicology

Ambient air, occupational settings, and the use and distribution of consumer products all serve as conduits for toxicant exposure through inhalation. While the pulmonary system remains a primary target following inhalation exposure, cardiovascular implications are exceptionally culpable for increased morbidity and mortality. The epidemiological evidence for cardiovascular dysfunction resulting from acute or chronic inhalation exposure to particulate matter has been well documented, but the mechanisms driving the resulting disturbances remain elusive. In the current review, we aim to summarize the cellular and molecular mechanisms that are directly linked to cardiovascular health following exposure to a variety of inhaled toxicants. The purpose of this review is to provide a comprehensive overview of the biochemical changes in the cardiovascular system following particle inhalation exposure and to highlight potential biomarkers that exist across multiple exposure paradigms. We attempt to integrate these molecular signatures in an effort to provide direction for future investigations. This review also characterizes how molecular responses are modified in at-risk populations, specifically the impact of environmental exposure during critical windows of development. Maternal exposure to particulate matter during gestation can lead to fetal epigenetic reprogramming, resulting in long-term deficits to the cardiovascular system. In both direct and indirect (gestational) exposures, connecting the biochemical mechanisms with functional deficits outlines pathways that can be targeted for future therapeutic intervention. Ultimately, future investigations integrating "omics"-based approaches will better elucidate the mechanisms that are altered by xenobiotic inhalation exposure, identify biomarkers, and guide in clinical decision making.

Ambient particulate matter oxidative potential: Chemical determinants, associated health effects, and strategies for risk management

Exposure to ambient air pollution has an adverse influence on human health. There is increasing evidence that oxidative potential (OP), the capacity of airborne pollutants to oxidize target molecules by generating redox oxidizing species, is a plausible metric for particulate matter (PM) toxicity. Here we describe the commonly used acellular techniques for measuring OP (respiratory tract lining fluid, dithiothreitol, ascorbic acid, and electron paramagnetic resonance assays) and review the PM chemical constituents that have been identified to drive the OP response. We further perform a review of the epidemiologic literature to identify studies that reported an association between exposure to ambient PM and a health outcome in a human population, and in which exposure was measured by both PM mass concentration and OP. Laboratory studies have shown that specific redox-active metals and quinones are able to contribute OP directly. However, interactions among PM species may alter the redox properties of PM components. In ambient PM measurements, all OP assays were found to be correlated with metals (Fe, Cu) and organic species (photochemically aged organics). Across the epidemiological studies reviewed, associations between fine PM (PM_2.5) mass and cardio-respiratory outcomes were found to be stronger at elevated OP levels but findings varied across the different OP measurement techniques. Future work should aim to identify specific situations in which PM OP can improve air pollution exposure assessment and/or risk management. This may be particularly useful in countries with low PM_2.5 mass concentrations over broad spatial scales where such information may greatly improve the efficiency of risk management activities.

Biomonitoring of Metals in Children Living in an Urban Area and Close to Waste Incinerators

The impact of waste incinerators is usually examined by measuring environmental pollutants. Biomonitoring has been limited, until now, to few metals and to adults. We explored accumulation of a comprehensive panel of metals in children free-living in an urban area hosting two waste incinerators. Children were divided by georeferentiation in exposed and control groups, and toenail concentrations of 23 metals were thereafter assessed. The percentage of children having toenail metal concentrations above the limit of detection was higher in exposed children than in controls for Al, Ba, Mn, Cu, and V. Exposed children had higher absolute concentrations of Ba, Mn, Cu, and V, as compared with those living in the reference area. The Tobit regression identified living in the exposed area as a significant predictor of Ba, Ni, Cu, Mn, and V concentrations, after adjusting for covariates. The concentrations of Ba, Mn, Ni, and Cu correlated with each other, suggesting a possible common source of emission. Exposure to emissions derived from waste incinerators in an urban setting can lead to body accumulation of specific metals in children. Toenail metal concentration should be considered a noninvasive and adequate biomonitoring tool and an early warning indicator which should integrate the environmental monitoring of pollutants.

Exposure to ambient dusty particulate matter impairs spatial memory and hippocampal LTP by increasing brain inflammation and oxidative stress in rats

OBJECTIVES

Exposure of healthy subjects to ambient airborne dusty particulate matter (PM) causes brain dysfunction. This study aimed to investigate the effect of sub-chronic inhalation of ambient PM in a designed special chamber to create factual dust storm (DS) conditions on spatial cognition, hippocampal long-term potentiation (LTP), inflammatory cytokines, and oxidative stress in the brain tissue.

METHODS

Adult male Wistar rats (250-300 g) were randomly divided into four groups: Sham (clean air, the concentration of dusty PM was <150 μg/m³), DS1 (200-500 μg/m³), DS2 (500-2000 μg/m³) and DS3 (2000-8000 μg/m³). Experimental rats were exposed to clean air or different sizes and concentrations of dust PM storm for four consecutive weeks (exposure was during 1-4, 8-11, 15-16 and 20-23 days, 30 min, twice daily) in a real-ambient dust exposure chamber. Subsequently, cognitive performance, hippocampal LTP, blood-brain barrier (BBB) permeability and brain edema of the animals evaluated. As well as, inflammatory cytokines and oxidative stress indexes in the brain tissue measured using ELISA assays.

RESULTS

Exposing to dust PM impaired spatial memory (p < 0.001), hippocampal LTP (p < 0.001). These disturbances were in line with the severe damage to respiratory system followed by disruption of BBB integrity (p < 0.001), increased brain edema (p < 0.001), inflammatory cytokines (p < 0.001) excretion and oxidative stress (p < 0.001) in brain tissue.

CONCLUSIONS

Our study showed that exposure to ambient dust PM increased brain edema and BBB permeability, induced memory impairment and hippocampal LTP deficiency by increasing the inflammatory responses and oxidative stress in the brain of the rats.

Culturability, metabolic activity and composition of ambient bacterial aerosols in a surrogate lung fluid

Interactions of particulate matter (PM) and respiratory tract play a crucial role in PM-related respiratory diseases. The majority of the work focuses on the oxidative stress induced by reactions between PM-borne redox-active components and lung lining fluid (LLF). The effects of PM-borne biological components are largely unknown. Of all PM-borne biologicals, bacteria, as living microorganisms, are closely related with inflammatory immune responses. However, its inhalation risk is usually determined without considering the respiratory physiological conditions. In this study, a surrogate lung fluid (SLF) with four typical antioxidants was applied to characterize the ambient bacteria, including concentrations of total bacteria/viable bacteria/culturable bacteria, metabolic activity, bacteria-derived endotoxin, as well as the community structure. Comparing to those determined by SLF, we find that use of PBS leads to an underestimation of the bacterial culturability and metabolic activity. No effect was seen regarding the number of total bacteria and viable bacteria (with intact membrane). Population structure change was seen for bacteria cultured from SLF-collected samples, when compared to that from PBS. Spore-forming bacteria, e.g., genus Bacillus, were found to be easily recovered with SLF. This implies that use of PBS could underestimate the bacteria inhalation risk, especially those bacterial endospores. Our work highlights the necessity to consider the respiratory airway environment when evaluating microbial inhalation risk.

Oxidative Potential Versus Biological Effects: A Review on the Relevance of Cell-Free/Abiotic Assays as Predictors of Toxicity from Airborne Particulate Matter

Background and Objectives: The oxidative potential (OP) of particulate matter (PM) in cell-free/abiotic systems have been suggested as a possible measure of their biological reactivity and a relevant exposure metric for ambient air PM in epidemiological studies. The present review examined whether the OP of particles correlate with their biological effects, to determine the relevance of these cell-free assays as predictors of particle toxicity. Methods: PubMed, Google Scholar and Web of Science databases were searched to identify relevant studies published up to May 2019. The main inclusion criteria used for the selection of studies were that they should contain (1) multiple PM types or samples, (2) assessment of oxidative potential in cell-free systems and (3) assessment of biological effects in cells, animals or humans. Results: In total, 50 independent studies were identified assessing both OP and biological effects of ambient air PM or combustion particles such as diesel exhaust and wood smoke particles: 32 in vitro or in vivo studies exploring effects in cells or animals, and 18 clinical or epidemiological studies exploring effects in humans. Of these, 29 studies assessed the association between OP and biological effects by statistical analysis: 10 studies reported that at least one OP measure was statistically significantly associated with all endpoints examined, 12 studies reported that at least one OP measure was significantly associated with at least one effect outcome, while seven studies reported no significant correlation/association between any OP measures and any biological effects. The overall assessment revealed considerable variability in reported association between individual OP assays and specific outcomes, but evidence of positive association between intracellular ROS, oxidative damage and antioxidant response in vitro, and between OP assessed by the dithiothreitol (DDT) assay and asthma/wheeze in humans. There was little support for consistent association between OP and any other outcome assessed, either due to repeated lack of statistical association, variability in reported findings or limited numbers of available studies. Conclusions: Current assays for OP in cell-free/abiotic systems appear to have limited value in predicting PM toxicity. Clarifying the underlying causes may be important for further advancement in the field.

Exposure to ultrafine particulate matter induces NF-κβ mediated epigenetic modifications

Exposure to ultrafine particulate matter (PM0.1) is positively associated with the etiology of different acute and chronic disorders; however, the in-depth biological imprints that link these submicron particles with the disturbances in the epigenomic machinery are not well defined. Earlier, we showed that exposure to these particles causes significant disturbances in the mitochondrial machinery and triggers PI-3-kinase mediated DNA damage responses. In the present study, we aimed to further understand the epigenomic insights of the ultrafine PM exposure. The higher levels of intracellular reactive oxygen species and depleted Nrf-2 in ultrafine PM exposed cells reconfirmed its potential to induce oxidative stress. Importantly, the observed increase in the levels of NF-κβ and associated cytokines among exposed cells suggested the activation of NF-κβ mediated inflammatory loop which potentially serves as a platform for initiating epigenetic insinuations. This fact was strongly supported by the altered miRNA expression profile of the ultrafine PM exposed cells. These NF-κβ induced miRNA alterations were also found to be associated with other epigenetic targets as the exposed cells showed higher expression levels of DNA methyltransferases which positively corresponded with the global changes in DNA methylation levels. Upon further analysis, significant alterations in histone code were also reported in ultrafine PM exposed cells. Conclusively our results suggested that NF-κβ acts as an inflammatory switch that possesses the potential to induce genome-wide epigenetic modification upon ultrafine PM exposure.