Cross-sectional and longitudinal associations between urinary zinc and lung function among urban adults in China

miR-629-3p inhibits fine particulate matter exposure-induced lung function decline: Results from the two-stage population study and in vitro study

MiRNAs were reported to play crucial roles in the pathogenesis of health damage caused by environmental pollutants. However, its potential role in fine particulate matter (PM2.5) exposure-induced lung function decline has rarely been elucidated. The present study was developed to profile specific miRNAs that were related to both PM2.5 exposure and lung function decline, and to investigate the regulating role in PM2.5 exposure-induced lung injury. Based on the Wuhan-Zhuhai cohort, in the discovery stage, plasma miRNA profiling for PM2.5 exposure was conducted through next-generation sequencing among 60 participants with 120 observations in a repeated-measures design. Plasma miRNA profiling for lung function decline was conducted among 10 pairs of lung function decline incident cases and matched healthy controls. In the validating stage, miR-629-3p was selected from miRNAs that were related to both PM2.5 exposure and lung function decline, and was measured by quantitative real-time PCR among 475 residents to validate its association with PM2.5 exposure as well as lung function. In vitro, PM2.5-treated A549 and BEAS-2B cell models and miR-629-3p mimic/inhibitor models were used to explore the role and underlying mechanism of miR-629-3p on epithelial-mesenchymal transition (EMT) induced by PM2.5 exposure. The two-stage population study found a negative association between personal PM2.5 exposure and plasma miR-629-3p, while a positive association between miR-629-3p and lung function. In vitro, PM2.5 treatment stimulated the expressions of EMT-related factors, accompanied by the activation of TGF-β1/TGF-βR1 signal pathway. Overexpression of miR-629-3p could inhibit PM2.5-induced TGF-βR1 expression and alleviate EMT process. And inhibition of miR-629-3p could promote TGF-βR1 expression and aggravate EMT process. In conclusion, miR-629-3p may alleviate the lung injury induced by PM2.5 exposure through inhibiting TGF-β1/TGF-βR1 pathway.

Investigation of the Mechanism of Oxidative Potential Increase in Atmospheric Particulate Matter during Photoaging: Important Role of Aromatic Nitrogenous Compounds

Particulate matter (PM) undergoing various aging processes in the atmosphere changes its toxicity. However, the mechanism of toxicity evolution is not fully clarified currently. This study demonstrates that photoaging promotes an increase in the oxidative potential (OP) of atmospheric PM by about 30%, and the increased OP is mainly attributed to the production of secondary organic compounds, while water-soluble metal ions contribute only 11%. The OP of nonextractable matters (NEMs) of atmospheric PM was mostly increased after photoaging, followed by water-soluble matters (WSMs). NEM can produce quinone-like functional groups and secondary persistent free radicals during photoaging, which are most likely to produce reactive oxygen species (ROS). For WSM, the conversion of low-oxidation humic-like substances (HULIS) to high-oxidation HULIS is the main reason for the increase in OP. Quinones, nitrophenols, and N-containing heterocycles are the OP contributors produced during the conversion process. Among them, quinones are the main secondary oxidizing active compounds, while nitro-phenolic compounds and N-containing heterocyclic compounds may play a catalyst-like role, facilitating the production of oxidizing active compounds and ROS in the newly converted high-oxidation HULIS. This study clarifies the secondary OP generation mechanism and provides new insights into the uncertainty of PM toxicity during atmospheric aging.

Zinc-associated phospholipid metabolic alterations and their impacts on ALT levels in workers

Zinc (Zn) is an essential trace element that is required for various biological functions, but excessive exposure to Zn is associated with many disorders and even diseases. However, the health effects and underlying mechanisms of long-term and high concentration exposure of Zn remain to be unclear. In the present study, we investigated the association between occupational exposure to Zn and liver function indicators (like alanine aminotransferase (ALT)) in workers. We found a positive association between Zn exposure and ALT level in workers. Workers having higher blood Zn (7735.65 (1159.15) μg/L) shows a 30.4 % increase in ALT level compared to those with lower blood Zn (5969.30 (989.26) μg/L). Furthermore, we explored the effects of phospholipids (PLs) and their metabolism on ALT level and discovered that Zn exposure in workers was associated with changes in PL levels and metabolism, which had further effects on increased ALT levels in workers. The study provides insights into the relationship between occupational Zn exposure and liver function, highlights the risk of long-term exposure to high concentrations of Zn, and paves the way for understanding the underlying mechanisms of Zn exposure on human health.

Associations of urinary zinc exposure with blood lipid profiles and dyslipidemia: Mediating effect of serum uric acid

The relationship between zinc (Zn) exposure and abnormal blood lipids including dyslipidemia is contentious. Serum uric acid (SUA) has been reported to be correlated to both Zn exposure and dyslipidemia. The underlying mechanisms of Zn exposure associated with blood lipids and the mediating effects of SUA remain unclear. Therefore, this study analyzed the data from Chinese 2110 adults (mean age: 59.0 years old) in rural areas across China to explore the associations of Zn exposure with blood lipid profiles and dyslipidemia, and to further estimate the mediating effects of SUA in these relationships. The study data showed that urinary Zn was associated with increased levels of blood lipid components triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). Moreover, an increased risk of dyslipidemia was observed in the study participants who had higher urinary Zn levels. Compared with the first quartile, the fourth quartile of urinary Zn concentration corresponded to the increase of TG (β = 0.20, 95 % CI: 0.12, 0.28), LDL-C (β = 0.06, 95 % CI: 0.01, 0.10) and dyslipidemia risk (OR = 2.16, 95 % CI: 1.50, 3.10), respectively. Elevated urinary Zn was also associated with higher levels of SUA and hyperuricemia risk. The SUA levels were positively related to total cholesterol (TC), TG, LDL-C levels and dyslipidemia risk. Mediation analyses revealed that SUA mediated 31.75 %, 46.16 % and 19.25 % of the associations of urinary Zn with TG, LDL-C levels and dyslipidemia risk, respectively. The subgroup and sensitivity analyses confirmed the positive associations between urinary Zn and blood lipid profiles and the mediating effect of SUA. The national population-based study further enhanced our understanding of the associations between Zn exposure and blood lipid profiles and mediating effect of SUA among generally healthy, middle-aged, and elderly individuals.

Longitudinal association of polycyclic aromatic hydrocarbons and genetic risk with lung function

To quantify the association of polycyclic aromatic hydrocarbons (PAHs) and the polygenic risk score (PRS) with lung function decline, we developed a repeated-measures study with 4681 observations from baseline and 6-year follow-up of the Wuhan-Zhuhai cohort. Lung function and urinary monohydroxylated PAH metabolites (OH-PAHs) were measured for each observation. The PRS was derived from 246 lung function-associated genetic variants weighted by the effect size of the decreasing ratio of forced expiratory volume in 1 s by forced vital capacity (FEV1/FVC). Linear mixed models were used to estimate the longitudinal exposure-response relationships between OH-PAHs and lung function, and to evaluate the interactions between OH-PAHs and PRS on the longitudinal change of lung function. We found that each 1-unit increase in log-transformed values of 9-hydroxyfluorene, 2-hydroxyfluorene, 4-hydroxyphenanthrene, 9-hydroxyphenanthrene, 2-hydroxyphenanthrene, 1-hydroxyphenanthrene, 1-hydroxypyrene, low molecular weight OH-PAHs (ΣLMW-OH-PAHs), and total OH-PAHs (ΣOH-PAHs) was associated with an annual change in FEV1/FVC of -0.140, -0.112, -0.260, -0.300, -0.159, -0.220, -0.145, -0.156, and -0.177 %/year, respectively. Interactions on the annual decline of FEV1/FVC were detected between ΣLMW-OH-PAHs and PRS (-0.010 %/year, 95% confidence interval -0.018 to -0.001, Pint = 0.0228), and between ΣOH-PAHs and PRS (-0.010 %/year, -0.018 to -0.001, Pint = 0.0203). These results indicated that specific and total urinary OH-PAHs were associated with the longitudinal FEV1/FVC decline, and ΣLMW-OH-PAHs as well as ΣOH-PAHs interacted with PRS on the annual decline of FEV1/FVC.

Cross-sectional and longitudinal associations of dichlorodiphenyltrichloroethane (DDT) metabolites exposure with lung function alternation in the Chinese general adults

Exposure of dichlorodiphenyltrichloroethane (DDT) pesticide was suggested to be associated with adverse effects on the respiratory system. However, the effects of DDT exposure on lung function remain unclear. Our objectives were to investigate the potential associations of internal levels of DDT and its metabolites including dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) with lung function. Serum DDT, DDE, and DDD concentrations and lung function were measured among 3968 general adults from the Wuhan-Zhuhai cohort. The cross-sectional and longitudinal associations of serum DDT and its metabolites with lung function were assessed using linear mixed models. The results showed negative dose-response relationships of serum DDT, DDE, and DDD levels with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). In the cross-sectional analyses, each 1-unit increase in natural log-transformed values of p,p'-DDE, o,p'-DDT, o,p'-DDE, or p,p'-DDD was significantly associated with a 25.77-, 44.84-, 51.13-, or 43.44-mL decrease in FVC, respectively. Each 1-unit increase in natural log-transformed values of o,p'-DDT, o,p'-DDE, o,p'-DDD, or p,p'-DDD was significantly associated with a 35.72-, 31.87-, 29.54-, or 36.80-mL decrease in FEV1, respectively. In the three-year longitudinal analyses, each 1-unit increase in natural log-transformed serum p,p'-DDT and p,p'-DDE was significantly associated with a 35.10 mL and 36.38 mL decrease in FVC, and a 26.32 mL and 32.37 mL decrease in FEV1, respectively. In conclusion, DDT and its metabolites exposure were associated with lung function decline in the general Chinese adult population.

Associations of multiple plasma metals with osteoporosis: findings from the Dongfeng-Tongji cohort

With the aging population, osteoporosis has become a more prevalent public health issue. Existing researches have indicated significant relations of single metal exposure with osteoporosis (e.g., lead, copper, and zinc), whereas the evidence regarding the joint association of metal mixtures with osteoporosis remain limited and inconclusive. A total of 4924 participants from the Dongfeng-Tongji cohort were included in the present study. Plasma levels of 23 metals were determined by inductively coupled plasma mass spectrometry, and the presence of osteoporosis was defined as a bone mineral density T-score ≤  - 2.5. We applied stepwise regression, plasma metal score, and quantile g-computation model to evaluate the association between plasma metal mixtures and osteoporosis risk. Of the 4924 participants, the prevalence of osteoporosis was 10.9% (N = 265) in males and 27.5% (N = 684) in females. In the multiple-metals model, arsenic was positively associated with osteoporosis in males, while zinc was positively associated with osteoporosis in females. Comparing extreme quartiles, the multivariate-adjusted ORs of osteoporosis were 2.20 (95% CI, 1.29, 3.79; P-trend = 0.006) for arsenic in males and 2.16 (95% CI, 1.44, 3.23; P-trend < 0.001) for zinc in females. The plasma metal score was significantly and positively associated with a higher risk of osteoporosis, with ORs (95% CI) comparing extreme quartiles were 5.00 (95% CI, 3.36, 7.65; P-trend < 0.001) in males and 1.76 (95% CI, 1.35, 2.29; P-trend < 0.001) in females. Furthermore, the results of quantile g-computation revealed a consistent positive trend of metal mixtures with risk of osteoporosis and suggested the dominant role of arsenic in males and zinc in females, respectively. Our findings highlighted the importance of controlling metal mixtures exposure for the prevention of osteoporosis in the middle-aged and elder population. Further prospective studies in larger populations are warranted to confirm our findings.

PM2.5-bound metals and blood metals are associated with pulmonary function and Th17/Treg imbalance: A panel study of asthmatic adults

Growing research has demonstrated that exposure to fine particulate matter (PM2.5) was associated with decreased pulmonary function and obvious inflammatory response. However, few pieces of research focus on the effects of PM2.5-bound metals on people with asthma. Here, we assessed whether PM2.5 and PM2.5-bound metals exposure could worsen pulmonary function in asthmatic patients and further elucidate the possible mechanisms. Thirty-four asthmatic patients were recruited to follow up for one year with eight visits in 2019-2020 in Taiyuan City, China. The index of pulmonary function was detected and blood and nasal epithelial lining fluid (ELF) samples were acquired for biomarkers measurement at each follow-up. Linear mixed-effect (LME) models were used to evaluate the relations between PM2.5, PM2.5-bound metals, and blood metals with lung function and biomarkers of Th17/Treg balance. The individual PM2.5 exposure concentration varied from 37 μg/m3 to 194 μg/m3 (mean: 59.63 μg/m3) in the present study. An interquartile range (IQR) increment of PM2.5 total mass was associated with a faster decline in maximal mid-expiratory flow (MMEF) and higher interleukin-23 (IL-23). PM2.5-bound metals [e.g. copper (Cu), nickel (Ni), manganese (Mn), titanium (Ti), and zinc (Zn)] were significantly associated with IL-23 (Cu: 5.1126%, 95% CI: 9.3708, 0.8544; Mn: 14.7212%, 95% CI: 27.926, 1.5164; Ni: 1.0269%, 95% CI: 2.0273, 0.0264; Ti: 16.7536%, 95% CI: 31.6203, 1.8869; Zn: 24.5806%, 95% CI: 46.609, 2.5522). Meanwhile, blood lead (Pb) and Cu were associated with significant declines of 0.382-3.895% in MMEF and maximum ventilatory volume (MVV). Blood Pb was associated with descending transforming growth factor β (TGF-β). In conclusion, exposure to PM2.5-bound metals and blood metals is a risk factor for decreased pulmonary function, especially in small airways. These alterations might be partially attributed to the imbalance of Th17/Treg.

Relationship of individual and mixed urinary metals exposure with liver function in the China National Human Biomonitoring (CNHBM) of Zhejiang Province

BACKGROUND

Heavy metals have been reported to affect liver function. However, there is currently little and inconsistent knowledge about the effects of combined and individual urinary metals on specific parameters of liver function in the general population. Therefore, this study aimed to investigate their associations.

METHODS

This study involved 807 general population from the China National Human Biomonitoring of Zhejiang Province 2017-2018. Concentrations of urinary metals, including Chromium (Cr), Cobalt (Co), Nickle (Ni), Arsenic (As), Selenium (Se), Molybdenum (Mo), Cadmium (Cd), Thallium (Tl) and Lead (Pb) were measured. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), direct bilirubin (DBIL), total bilirubin (TBIL) as liver function biomarkers. Multivariable linear regression and weighted quantile sum (WQS) regression were employed to explore the associations of urinary metals with liver function biomarkers. Subgroup analysis stratified by gender and age, excluding smokers and drinkers for sensitivity analysis.

RESULTS

Both statistical models indicated that urinary metals were positively associated with ALT and AST, while negatively with TP, ALB, DBIL and TBIL. In the WQS analysis, each quartile increase in the ln-transformed levels of metal mixtures was associated with 4.11 IU/L (95% CI: 1.07, 7.15) higher ALT and 3.00 IU/L (95% CI: 1.75, 4.25) higher AST, as well as, with 0.67 g/L (95% CI: 1.24, -0.11) lower TP, 0.74 g/L (95% CI: 1.09, -0.39) lower ALB, 0.38 μmol/L (95% CI: 0.67, -0.09) lower DBIL, and 1.56 μmol/L (95% CI: 2.22, -0.90) lower TBIL. The association between urinary metals and ALT was primarily driven by Cd (55.8%), Cr contributed the most to the association with AST (20.2%) and TBIL (45.2%), while the association with TP was primarily driven by Ni (38.2%), the association with ALB was primarily driven by As (32.8%), and the association with DBIL was primarily driven by Pb (30.9%). The associations between urinary metals and liver function might differ by sex and age.

CONCLUSION

Urinary metals were significantly associated with liver function parameters. Further studies are required to clarify the relationship between heavy metals and liver function.

Blood multiple heavy metals exposure and lung function in young adults: A prospective Cohort study in China

The content of single heavy metal in blood is associated with lung function decline, but there is little evidence on the joint effect of multiple heavy metals on lung function. To explore whether heavy metal mixture exposure is associated with lung function reduction among young adults. The study based on a cohort of 518 students recruited from a college in Shandong, China. We measured their lung function and blood heavy metal concentrations. The BKMR model was used to analyse the association between blood heavy metals mixture levels and lung function, and to identify the critical single heavy metal which contributes most to joint effects. As the sensitivity analysis, we used quantile g-computation model and GLM to explore the joint effect and independent effects of heavy metals. Our findings revealed a significant reduction of FVC and FEV1 levels after exposure to heavy metals mixture. An IQR increase in Cu was associated with a 0.079 L and 0.083 L decrease in FEV1 and FVC, respectively. And an IQR increase in Fe was associated with 0.036 L higher FEV1 and 0.033 L higher FVC. For adults, reducing blood heavy metals concentration might be an effective intervention to protect lung function.

The association between multi-heavy metals exposure and lung function in a typical rural population of Northwest China

BACKGROUND

Heavy metal exposure is acknowledged to be associated with decrease of lung function, but the relationship between metals co-exposure and lung function in rural areas of Northwest China remains unclear, particularly in an area famous for heavy metal pollution and solid fuel use. Therefore, the purpose of this study is to explore the effects of heavy metal exposure on lung function and the potential impacts of living habit in a rural cohort of Northwest China.

METHODS

The study area included five villages of two regions in Northwestern China-Gansu province. All participants were recruited from the Dongdagou-Xinglong (DDG-XL) rural cohort in the study area. Urine levels of 10 common and representative heavy metals were detected by ICP-MS, including Cobalt (Co), Nickel (Ni), Molybdenum (Mo), Cadmium (Cd), Stibium (Sb), Copper (Cu), Zinc (Zn), Mercury (Hg), Lead (Pb), and Manganese (Mn). The lung function was detected by measuring percentages of predicted forced vital capacity (FVC%) and predicted forced expiratory volume in one second (FEV1%) as well as the ratio of FEV1/FVC. We also analyzed the association between heavy metals and pulmonary ventilation dysfunction (PVD). Restricted cubic spline, logistic regression, linear regression, and bayesian kernel machine regression (BKMR) model were used to analyze the relationship between heavy metal exposure and lung function.

RESULTS

Finally, a total of 382 participants were included in this study with an average age of 56.69 ± 7.32 years, and 82.46% of them used solid fuels for heating and cooking. Single metal exposure analysis showed that the higher concentration of Hg, Mn, Sb, and lower Mo may be risk factors for PVD. We also found that FEV1% and FVC% were negatively correlated with Sb, Hg, and Mn, but positively correlated with Mo. The effect of mixed heavy metals exposure could be observed through BKMR model, through which we found the lung function decreased with the increase of heavy metal concentration. Furthermore, the males, BMI ≥ 24 kg/m2 and who used solid fuels showed a higher risk of PVD when exposed to Co, Zn, and Hg.

CONCLUSIONS

Our results suggested that heavy metal exposure was associated with decrease of lung function regardless of single exposure or mixed exposure, particularly for Sb, Hg, Mn and those who use solid fuels.

Metal Exposure-Related Welder's Pneumoconiosis and Lung Function: A Cross-Sectional Study in a Container Factory of China

Long-term inhalation of welding fume at high exposure can cause welder's pneumoconiosis, and metals in welding dust are associated with respiratory dysfunction. This cross-sectional study, which contains 384 Chinese male workers who were or had been working in a container factory, aimed to assess the potential risk of haemal and urinary metal content in welder's pneumoconiosis. Further, we investigated their effects on lung function parameters. Metal content and lung function were measured using inductively coupled plasma-mass spectrometry (ICP-MS) and spirometer, respectively. The concentration and metal content of respirable dust as well as total dust were collected at this container factory. Lung function of cases with welder's pneumoconiosis was significantly worse, as indicated by lower values of FVC, FVC% predicted, FEV1, FEV1% predicted, MEF25% predicted, and MMEF% predicted (p < 0.05). Results of logistic regression models showed that haemal Cr and Zn were risk factors of welder's pneumoconiosis (OR = 4.98, 95%CI: 1.73-21.20, p = 0.009 for Cr; OR = 5.23, 95%CI: 1.56-41.08, p = 0.033 for Zn) after adjusted with age, BMI, working years, welding dust exposure years, and smoking status. Multiple linear regression models showed that several metals (haemal Cd and Pb; urinary Cd and Fe) were significantly associated with different lung function indices in the welder's pneumoconiosis group. Compared to non-welders, welders were exposed to considerably higher levels of respirable dust, total dust, and six kinds of metals (p < 0.05). In conclusion, haemal Cr and Zn are positively related to welder's pneumoconiosis. Meanwhile, Cd and Pb might worsen lung function in welder's pneumoconiosis.

Cross-sectional and longitudinal associations of urinary zinc with glucose-insulin homeostasis traits and type 2 diabetes: Exploring the potential roles of systemic inflammation and oxidative damage in Chinese urban adults

The link between zinc exposure and glucose metabolism or the development of type 2 diabetes (T2D) is controversial, and underlying mechanisms are unclear. This study aimed to explore the associations of zinc exposure with glucose-insulin homeostasis traits and the long-term effects of zinc on the development of T2D, and further to estimate the potential roles of inflammation and oxidative damage in such relationships. We investigated 3890 urban adults from the Wuhan-Zhuhai cohort, and followed up every three years. Mixed linear model was applied to estimate dose-response associations between urinary zinc and glycemia traits [fasting plasma insulin (FPI), fasting plasma glucose (FPG), insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR), and β-cell dysfunction (homeostasis model assessment of β-cell function, HOMA-B)], as well as zinc and biomarkers for systemic inflammation (C-reactive protein) and oxidative damage (8-isoprostane and 8-hydroxy-2'-deoxyguanosine). Logistic regression model and Cox regression model were conducted to evaluate the relationships between urinary zinc and prevalence and incidence of T2D, respectively. We further performed mediation analysis to assess the roles of inflammation and oxidative damage biomarkers in above associations. At baseline, we observed significant dose-response relationships of elevated urinary zinc with increased FPI, FPG, HOMA-IR, and T2D prevalence and decreased HOMA-B, and such associations could be strengthened by increased C-reactive protein, 8-isoprostane, and 8-hydroxy-2'-deoxyguanosine. Elevated C-reactive protein significantly mediated 9.09% and 17.67% of the zinc-related FPG and HOMA-IR increments, respectively. In longitudinal analysis, a significantly positive association between urinary zinc and T2D incidence was observed among subjects with persistent high urinary zinc levels when compared with those with persistent low zinc levels. Our results suggested that high levels of zinc exposure adversely affected on glucose-insulin homeostasis and further contributed to increased risk of T2D cross-sectionally and longitudinally. Moreover, inflammatory response might play an important role in zinc-related glucose metabolic disorder.

Long-term personal PM2.5 exposure and lung function alternation: A longitudinal study in Wuhan urban adults

BACKGROUND

The effect of long-term PM_2.5 exposure on lung function has not been well established.

OBJECTIVES

To investigate the effects of long-term personal PM_2.5 exposure on lung function decline, obstructive, and restrictive ventilatory disorders.

METHOD

Personal PM_2.5 concentrations were evaluated using an estimation model. Lung function parameters including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁) and peak expiratory flow (PEF) were measured in 3053 Wuhan participants from the Wuhan-Zhuhai cohort and were repeated every 3 years. Participants were classified into persistently high exposure group, persistently low exposure group and inconsistent exposure group according to the median of PM_2.5 concentration of each visit. Mixed linear models with subject-specific random intercept were used to assess the association of 3-year change of lung function with personal PM_2.5 exposure, and generalized linear models were used to assess the association of 6-year change of lung function with personal PM_2.5 exposure. Cox regression models were applied to assess the associations of PM_2.5 with obstructive and restrictive ventilatory disorders.

RESULTS

The medians of personal PM_2.5 concentrations at baseline and two follow-ups were 153.18, 209.57 and 83.78 μg/m³, respectively. Compared with participants in the persistently low exposure group, participants in the persistently high exposure group showed a 2.99 % (95 % CI: 0.91, 5.08), a 380.15 mL/s (95 % CI: 32.82, 727.48) and a 5.98 % (95 % CI: 0.84, 11.11) additional decline in FEV₁/FVC, PEF and PEFpred after 6 years, respectively. Stratified analyses showed that age, gender, body mass index, smoking status and drinking status had no significant modification effect on the associations. The associations of PM_2.5 exposure with obstructive and restrictive ventilatory disorders were not significant, except for a positive association between persistently high PM_2.5 exposure and restrictive ventilatory disorder among ever drinkers.

CONCLUSION

Long-term high PM_2.5 exposure was associated with FEV₁/FVC, PEF and PEFpred declines.

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.

Cross-sectional and longitudinal associations of acrolein exposure with pulmonary function alteration: Assessing the potential roles of oxidative DNA damage, inflammation, and pulmonary epithelium injury in a general adult population

BACKGROUND

Acrolein is a significant high priority hazardous air pollutant with pulmonary toxicity and the leading cause of most noncancer adverse respiratory effects among air toxics that draws great attention. Whether and how acrolein exposure impacts pulmonary function remain inconclusive.

OBJECTIVES

To assess the association of acrolein exposure with pulmonary function and the underlying roles of oxidative DNA damage, inflammation, and pulmonary epithelium integrity.

METHODS

Among 3,279 Chinese adults from the Wuhan-Zhuhai cohort, associations of urinary acrolein metabolites (N-Acetyl-S-(2-carboxyethyl)-L-cysteine, CEMA; N-Acetyl-S-(3-hydroxypropyl)-L-cysteine, 3HPMA) as credible biomarkers of acrolein exposure with pulmonary function were analyzed by linear mixed models. Joint effects of biomarkers of oxidative DNA damage (8-hydroxy-deoxyguanosine), inflammation (C-reactive protein, CRP), and pulmonary epithelium integrity (Club cell secretory protein, CC16) with acrolein metabolites on pulmonary function and the mediating roles of these biomarkers were assessed. Besides, a subgroup (N = 138) was randomly recruited from the cohort to assess the stabilities of acrolein metabolites and their longitudinal associations with pulmonary function change in three years.

RESULTS

Significant inverse dose-response relationships between acrolein metabolites and pulmonary function were found. Each 10-fold increment in CEMA, 3HPMA, or ΣUACLM (CEMA + 3HPMA) was cross-sectionally related to a 68.56-, 40.98-, or 46.02-ml reduction in FVC and a 61.54-, 43.10-, or 50.14-ml reduction in FEV₁, respectively (P < 0.05). Furthermore, acrolein metabolites with fair to excellent stabilities were found to be longitudinally associated with pulmonary function decline in three years. Joint effects of acrolein metabolites with 8-hydroxy-deoxyguanosine, CRP, and CC16 on pulmonary function were identified. CRP significantly mediated 5.97% and 5.51% of CEMA-associated FVC and FEV₁ reductions, respectively. 8-hydroxy-deoxyguanosine significantly mediated 6.78%, 6.88%, and 7.61% of CEMA-, 3HPMA-, and ΣUACLM-associated FVC reductions, respectively.

CONCLUSIONS

Acrolein exposure of general adults was cross-sectionally and longitudinally related to pulmonary function decline, which was aggravated and/or partly mediated by oxidative DNA damage, inflammation, and pulmonary epithelium injury.

A review of practical statistical methods used in epidemiological studies to estimate the health effects of multi-pollutant mixture

Environmental risk factors have been implicated in adverse health effects. Previous epidemiological studies on environmental risk factors mainly analyzed the impact of single pollutant exposure on health, while in fact, humans are constantly exposed to a complex mixture consisted of multiple pollutants/chemicals. In recent years, environmental epidemiologists have sought to assess adverse health effects of exposure to multi-pollutant mixtures based on the diversity of real-world environmental pollutants. However, the statistical challenges are considerable, for instance, multicollinearity and interaction among components of the mixture complicate the statistical analysis. There is currently no consensus on appropriate statistical methods. Here we summarized the practical statistical methods used in environmental epidemiology to estimate health effects of exposure to multi-pollutant mixture, such as Bayesian kernel machine regression (BKMR), weighted quantile sum (WQS) regressions, shrinkage methods (least absolute shrinkage and selection operator, elastic network model, adaptive elastic-net model, and principal component analysis), environment-wide association study (EWAS), etc. We sought to review these statistical methods and determine the application conditions, strengths, weaknesses, and result interpretability of each method, providing crucial insight and assistance for addressing epidemiological statistical issues regarding health effects from multi-pollutant mixture.

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.

Environmental-level exposure to metals and metal-mixtures associated with spirometry-defined lung disease in American Indian adults: Evidence from the Strong Heart Study

BACKGROUND

American Indians have a higher burden of chronic lung disease compared to the US average. Several metals are known to induce chronic lung disease at high exposure levels; however, less is known about the role of environmental-level metal exposure. We investigated respiratory effects of exposure to single metals and metal-mixtures in American Indians who participated in the Strong Heart Study.

METHODS

We included 2077 participants with data on 6 metals (As, Cd, Mo, Se, W, Zn) measured from baseline urine samples (1989-1991) and who underwent spirometry testing at follow-up (1993-1995). We used generalized linear regression to assess associations of single metals with spirometry-defined measures of airflow limitation and restrictive ventilatory pattern, and continuous spirometry. We used Bayesian Kernel Machine Regression to investigate the joint effects of the metal-mixture. Sensitivity analyses included stratifying by smoking status and diabetes.

RESULTS

Participants were 40% male, with median age 55 years. 21% had spirometry-defined airflow limitation, and 14% had a restrictive ventilatory pattern. In individual metal analyses, Cd was associated with higher odds of airflow limitation and lower FEV1 and FEV1/FVC. Mo was associated with higher odds of restrictive ventilatory pattern and lower FVC. Metal-mixtures analyses confirmed these models. In smoking stratified analyses, the overall metal-mixture was linearly and positively associated with airflow limitation among non-smokers; Cd was the strongest contributor. For restrictive ventilatory pattern, the association with the overall metal-mixture was strong and linear among participants with diabetes and markedly attenuated among participants without diabetes. Among those with diabetes, Mo and Zn were the major contributors.

CONCLUSIONS

Environmental-level exposure to several metals was associated with higher odds of spirometry-defined lung disease in an American Indian population. Exposure to multiple metals, including Cd and Mo, may have an under-recognized adverse role on the respiratory system.

Longitudinal relationships between polycyclic aromatic hydrocarbons exposure and heart rate variability: Exploring the role of transforming growth factor-β in a general Chinese population

We aim to investigate the long-term adverse effects of polycyclic aromatic hydrocarbons (PAHs) exposure on heart rate variability (HRV) reduction, and to assess the potential role of transforming growth factor-β1 (TGF-β1) in such relationship. We enrolled 2985 adult residents with 4100 observations who participated at baseline and 6-years follow-up from Wuhan-Zhuhai cohort. Ten detectable urinary PAHs metabolites and two HRV indices were repeatedly measured at baseline and follow-up; and plasma TGF-β1 levels were also determined for all subjects. We observed that both total urinary low molecular weight PAHs (ΣLWM OH-PAH) and total urinary high molecular weight PAHs (ΣHWM OH-PAH) were negatively associated with HRV reductions (P < 0.05). Subjects with persistent high levels of ΣHWM OH-PAH had a significant reduction in HRV over 6 years, and the incensement of TGF-β1 could aggravate above adverse effects in a dose-response manner. All kinds of PAHs were positively associated with plasma TGF-β1 elevation, which in turn, were negatively related to HRV indices. Increased TGF-β1 significant mediated 1.34-3.62% of PAHs-associated HRV reduction. Our findings demonstrated that long-term high levels of PAHs exposure could cause HRV reductions, and TGF-β1 may play an essential role in such association.

Multiple plasma metals, genetic risk and serum complement C3, C4: A gene-metal interaction study

Exposure to metals and metalloids is widely related with human health, and could affect the function of immune system. The complement system links innate and adaptive immunity, and is critically involved in the pathogenesis of inflammatory and immune diseases. The third and fourth components of complement (C3, C4) play key roles in the complement system. However, few studies have examined the relations between multiple metals and complement levels. In this study, based on a total of 2977 participants from the Dongfeng-Tongji cohort, China, we investigated 17 plasma metals and serum C3, C4 levels, and calculated C3/C4-associated genetic risk scores (GRSs) using established single nucleotide polymorphisms. We further explored the potential gene-metal interactions on C3 and C4. After multivariable adjustment, an increment of 10-standard deviation increase in natural log-transformed exposure concentrations of plasma copper was associated with 0.549 (0.489, 0.608) (FDR <0.0001), and 1.146 (0.999, 1.294) (FDR <0.0001) higher natural log-transformed serum C3 and C4 levels, respectively. While each increment of 10-standard deviation of natural log-transformed zinc was associated with a difference of 0.083 (0.024, 0.143) (FDR = 0.049) and 0.007 (-0.138, 0.152) (FDR = 0.935) in log-transformed C3 and C4 levels, respectively. Participants with higher GRS had higher C3 and C4 levels. Furthermore, we found a significant interaction between arsenic exposure and C3-GRS in relation to C3 level (P_interaction = 0.0096). Our results suggested that plasma arsenic would modify the association between C3 genetic predisposition and serum C3 level. We provide new insight into metals exposure on the human immune system. These findings require replication in future research.

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.

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.