Oxidative DNA damage mediates the association between urinary metals and prevalence of type 2 diabetes mellitus in Chinese adults

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.

Reference values for plasma and urine trace elements in a Swiss population-based cohort

OBJECTIVES

Trace elements (TEs) are ubiquitous. TE concentrations vary among individuals and countries, depending on factors such as living area, workplaces and diet. Deficit or excessive TEs concentrations have consequences on the proper functioning of human organism so their biomonitoring is important. The aim of this project was to provide reference values for TEs concentrations in the Swiss population.

METHODS

The 1,078 participants to the SKiPOGH cohort included in this study were aged 18-90 years. Their 24-h urine and/or plasma samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine 24 TEs concentrations: Ag, Al, As, Be, Bi, Cd, Co, Cr, Cu, Hg, I, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Se, Sn, Tl, V and Zn. Statistical tests were performed to evaluate the influence of covariates (sex, age, BMI, smoking) on these results. Reference intervals for the Swiss adult population were also defined.

RESULTS

TEs concentrations were obtained for respectively 994 and 903 persons in plasma and urine matrices. It was possible to define percentiles of interest (P50 and P95) for almost all the TEs. Differences in TEs distribution between men and women were noticed in both matrices; age was also a cofactor.

CONCLUSIONS

This first Swiss biomonitoring of a large TEs-panel offers reference values in plasma and in urine for the Swiss population. The results obtained in this study were generally in line with clinical recommendations and comparable to levels reported in other population-based surveys.

Association of urinary arsenic metabolism with type 2 diabetes and glucose homeostasis: Cross-sectional and longitudinal associations

BACKGROUND

Previous researches have assessed the relationships of urinary arsenic metabolism with type 2 diabetes (T2D) and glucose-insulin homeostasis, but the results were controversial, and potential mechanisms remain largely unclear.

OBJECTIVES

This study aimed to investigate the cross-sectional and longitudinal associations of urinary arsenic metabolism with T2D prevalence and glucose changes in relatively higher arsenic exposure, and further to evaluate the underlying roles of oxidative damage in these relationships.

METHODS

We included 796 participants at baseline, among them 509 participants were followed up after 2 years. Logistic regression model and leave-one-out approach were applied to evaluate the associations of arsenic metabolism with T2D prevalence. Linear mixed model was conducted to estimate the relationship of arsenic metabolism with glycemic changes over two years. The associations between arsenic metabolism and indicators of oxidative stress were assessed with a linear regression model. We further performed mediation analysis to investigate the role of oxidative stress in the associations of arsenic metabolism with 2-year change of glucose levels.

RESULTS

Higher urinary MMA% increased T2D prevalence and baseline glucose levels. MMA% was positively associated with 2-year change of glucose levels. Moreover, we observed significant dose-response relationship between MMA% and 8-hydroxy-2-deoxyguanosine (8-OHdG). However, the mediating role of 8-OHdG in the association of MMA% and 2-year change of glucose levels was not observed in this population.

CONCLUSIONS

In this population exposure to relatively higher arsenic levels, higher MMA% contributed to increased T2D prevalence and glucose homeostasis disorder. Arsenic metabolism also affected oxidative stress levels, especially 8-OHdG. Further studies are required to investigate the potential mechanisms.

Associations between multiple metals during early pregnancy and gestational diabetes mellitus under four statistical models

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. Metal exposure is an emerging factor affecting the risk of GDM. However, the effects of metal mixture on GDM and key metals within the mixture remain unclear. This study was aimed at investigating the association between metal mixture during early pregnancy and the risk of GDM using four statistical methods and further at identifying the key metals within the mixture associated with GDM. A nested case-control study including 128 GDM cases and 318 controls was conducted in Beijing, China. Urine samples were collected before 13 gestational weeks and the concentrations of 13 metals were measured. Single-metal analysis (unconditional logistic regression) and mixture analyses (Bayesian kernel machine regression (BKMR), quantile g-computation, and elastic-net regression (ENET) models) were applied to estimate the associations between exposure to multiple metals and GDM. Single-metal analysis showed that Ni was associated with lower risk of GDM, while positive associations of Sr and Sb with GDM were observed. Compared with the lowest quartile of Ni, the ORs of GDM in the highest quartiles were 0.49 (95% CI 0.24, 0.98). In mixture analyses, Ni and Mg showed negative associations with GDM, while Co and Sb were positively associated with GDM in BKMR and quantile g-computation models. No significant joint effect of metal mixture on GDM was observed. However, interestingly, Ni was identified as a key metal within the mixture associated with decreased risk of GDM by all three mixture methods. Our study emphasized that metal exposure during early pregnancy was associated with GDM, and Ni might have important association with decreased GDM risk.

An updated systematic review and dose-response meta-analysis on the relation between exposure to arsenic and risk of type 2 diabetes

Arsenic is among the most critical environmental toxicants associated with many human disorders. However, its effect on type 2 diabetes mellitus (T2DM) is contradictory. This systematic review and dose-response meta-analysis aim to update information on the association between arsenic exposure and the risk of T2DM. The sample type (drinking water, urine, blood, and nails) conducted the subgroup analysis. Evaluation of the high vs. low arsenic concentrations showed a significant association between drinking water arsenic (OR: 1.58, 95% CI: 1.20-2.08) and urinary arsenic (OR: 1.37, 95% CI: 1.24-1.51) with the risk of T2DM. The linear dose-response meta-analysis showed that each 1 μg/L increase in levels of drinking water arsenic (OR: 1.01, 95% CI: 1.00-1.01) and urinary arsenic (OR: 1.01, 95% CI: 1.00-1.02) was associated with a 1% increased risk of T2DM. The non-linear dose-response analysis indicated that arsenic in urine was associated with the risk of T2DM (Pnon-linearity<0.001). However, this effect was not statistically significant for arsenic in drinking water (Pnon-linearity=0.941). Our findings suggest that blood arsenic was not significantly linked to the increased risk of T2DM in high vs. low (OR: 1.21, 95% CI: 0.85-1.71), linear (OR: 1.04, 95% CI: 0.99-1.09), and non-linear (Pnon-linearity=0.365) analysis. Also, nail arsenic was not associated with the risk of T2DM in this meta-analysis (OR: 1.33, 95% CI: 0.69-2.59). This updated dose-response meta-analysis indicated that arsenic exposure was significantly correlated with the risk of T2DM.

Cross-sectional and longitudinal relationships between ozone exposure and glucose homeostasis: Exploring the role of systemic inflammation and oxidative stress in a general Chinese urban population

The adverse health effects of ozone pollution have been a globally concerned public health issue. Herein we aim to investigate the association between ozone exposure and glucose homeostasis, and to explore the potential role of systemic inflammation and oxidative stress in this association. A total of 6578 observations from the Wuhan-Zhuhai cohort (baseline and two follow-ups) were included in this study. Fasting plasma glucose (FPG) and insulin (FPI), plasma C-reactive protein (CRP, biomarker for systemic inflammation), urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG, biomarker for oxidative DNA damage), and urinary 8-isoprostane (biomarker for lipid peroxidation) were repeatedly measured. After adjusting for potential confounders, ozone exposure was positively associated with FPG, FPI, and homeostasis model assessment of insulin resistance (HOMA-IR), and negatively associated with HOMA of beta cell function (HOMA-β) in cross-sectional analyses. Each 10 ppb increase in cumulative 7-days moving average ozone was associated with a 13.19%, 8.31%, and 12.77% increase in FPG, FPI, and HOMA-IR, respectively, whereas a 6.63% decrease in HOMA-β (all P < 0.05). BMI modified the associations of 7-days ozone exposure with FPI and HOMA-IR, and the effects were stronger in subgroup whose BMI ≥24 kg/m². Consistently high exposure to annual average ozone was associated with increased FPG and FPI in longitudinal analyses. Furthermore, ozone exposure was positively related to CRP, 8-OHdG, and 8-isoprostane in dose-response manner. Increased CRP, 8-OHdG, and 8-isoprostane could dose-dependently aggravate glucose homeostasis indices elevations related to ozone exposure. Increased CRP and 8-isoprostane mediated 2.11-14.96% of ozone-associated glucose homeostasis indices increment. Our findings suggested that ozone exposure could cause glucose homeostasis damage and obese people were more susceptible. Systemic inflammation and oxidative stress might be potential pathways in glucose homeostasis damage induced by ozone exposure.

Multiple metal exposure and metabolic syndrome in elderly individuals: A case-control study in an active mining district, Northwest China

The prevalence of metabolic syndrome (MetS) is increasing at an alarming rate worldwide, particularly among elderly individuals. Exposure to various metals has been linked to the development of MetS. However, limited studies have focused attention on the elderly population living in active mining districts. Participants with MetS (N = 292) were matched for age (±2 years old) and sex with a healthy subject (N = 292). We measured the serum levels of 14 metals in older people aged 65-85 years. Conditional logistic regression, restricted cubic spline model, multiple linear regression, and Bayesian Kernel Machine Regression (BKMR) were applied to estimate potential associations between multiple metals and the risk of MetS. Serum levels of Sb and Fe were significantly higher than the controls (0.58 μg/L vs 0.46 μg/L, 2167 μg/L vs 2042 μg/L, p < 0.05), while Mg was significantly lower (20035 μg/L vs 20,394 μg/L, p < 0.05). An increased risk of MetS was associated with higher serum Sb levels (adjusted odds ratio (OR) = 1.61 for the highest tertile vs. the lowest tertile, 95% CI = 1.08-2.40, p-trend = 0.018) and serum Fe levels (adjusted OR = 1.55 for the highest tertile, 95% CI = 1.04-2.33, p-trend = 0.032). Higher Mg levels in serum may have potential protective effects on the development of MetS (adjusted OR = 0.61 for the highest tertile, 95% CI = 0.41-0.91, p-trend = 0.013). A joint exposure analysis by the BKMR model revealed that the mixture of 12 metals (except Tl and Cd) was associated with increased risk of MetS. Our results indicated that exposure to Sb and Fe might increase the risk of MetS in an elderly population living in mining-intensive areas. Further work is needed to confirm the protective effect of Mg on MetS.

Cross-sectional and Longitudinal Associations Between Propylene Oxide Exposure and Lung Function Among Chinese Community Residents: Roles of Oxidative DNA Damage, Lipid Peroxidation, and Protein Carbonylation

BACKGROUND

Toxicologic studies have reported propylene oxide (PO) exposure may harm the respiratory system, but the association between PO exposure and lung function and potential mechanism remains unclear.

RESEARCH QUESTION

What is the association between PO exposure and lung function and potential mediating mechanism?

STUDY DESIGN AND METHODS

Urinary PO metabolite [N-Acetyl-S-(2-hydroxypropyl)-L-cysteine (2HPMA)] as PO internal exposure biomarker and lung function were measured for 3,692 community residents at baseline and repeated at 3-year follow up. Cross-sectional and longitudinal associations between urinary 2HPMA and lung function were assessed by linear mixed model. Urinary 8-hydroxy-deoxyguanosine, urinary 8-iso-prostaglandin-F2α, and plasma protein carbonyls as biomarkers of oxidative DNA damage, lipid peroxidation, and protein carbonylation, respectively, were measured for all participants to explore their potential roles in 2HPMA-associated lung function decline by mediation analysis.

RESULTS

After adjustment for potential covariates, each threefold increase in urinary 2HPMA was cross sectionally associated with a 26.18 mL (95% CI, -50.55 to -1.81) and a 21.83 mL (95% CI, -42.71 to -0.95) decrease in FVC and FEV1, respectively, at baseline (all P < .05). After 3 years of follow up, 2HPMA was observed to be longitudinally associated with FEV1/FVC decline. No significant interaction effect of smoking or passive smoking was observed (Pinteraction > .05), and the associations between 2HPMA and lung function indexes were persistent among participants who were not smoking and those who were not passive smoking in both baseline and follow-up evaluations. We observed urinary 8-hydroxy-deoxyguanosine partially mediated the associations of 2HPMA with FVC (mediation proportion, 5.48%) and FEV1 (mediation proportion, 6.81%), and plasma protein carbonyl partially mediated the association between 2HPMA and FEV1 (mediation proportion, 3.44%).

INTERPRETATION

PO exposure was associated with lung function decline among community residents, and oxidative DNA damage and protein carbonylation partially mediated PO exposure-associated lung function decline. Further attention on respiratory damage caused by PO exposure is warranted.

Acrolein Exposure Impaired Glucose Homeostasis and Increased Risk of Type 2 Diabetes: An Urban Adult Population-Based Cohort Study with Repeated Measures

Acrolein is an identified high-priority hazardous air pollutant ubiquitous in daily life and associated with cardiometabolic risk that attracts worldwide attention. However, the etiology role of acrolein exposure in glucose dyshomeostasis and type 2 diabetes (T2D) is unclear. This repeated-measurement prospective cohort study included 3522 urban adults. Urine/blood samples were repeatedly collected for determinations of acrolein metabolites (N-acetyl-S-(3-hydroxypropyl)-l-cysteine, N-acetyl-S-(2-carboxyethyl)-l-cysteine; acrolein exposure biomarkers), glucose homeostasis, and T2D at baseline and a three-year follow-up. We found that each 3-fold increment in acrolein metabolites was cross-sectionally associated with 5.91-6.52% decrement in homeostasis model assessment-insulin sensitivity (HOMA-IS) and 0.07-0.14 mmol/L, 4.02-4.57, 5.91-6.52, 19-20, 18-19, and 23-31% increments in fasting glucose (FPG), fasting insulin (FPI), HOMA-insulin resistance (HOMA-IR), risks of prevalent IR, impaired fasting glucose (IFG), and T2D, respectively; longitudinally, participants with sustained-high acrolein metabolite levels had increased risks of incident IR, IFG, and T2D by 63-80, 87-99, and 120-154%, respectively (P < 0.05). In addition, biomarkers of heme oxygenase-1 activity (exhaled carbon monoxide), lipid peroxidation (8-iso-prostaglandin-F2α), protein carbonylation (protein carbonyls), and oxidative DNA damage (8-hydroxy-deoxyguanosine) mediated 5.00-38.96% of these associations. Our study revealed that acrolein exposure may impair glucose homeostasis and increase T2D risk via mediating mechanisms of heme oxygenase-1 activation, lipid peroxidation, protein carbonylation, and oxidative DNA damage.

Exposure to multiple metals and diabetes mellitus risk in dong ethnicity in China: from the China multi-ethnic cohort study

Metals play an important role in the development of diabetes mellitus (DM). The association of metals with diabetes among the Dong ethnicity in China remains poorly understood. The current study aimed to evaluate the association of single metal exposure and multi-metal co-exposure with DM risk. Urinary concentrations of arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, molybdenum, nickel, strontium, vanadium, and zinc were measured using inductively coupled plasma-mass spectrometry (ICP-MS) among 4479 Dong ethnic participants aged 30-79 years from the China Multi-Ethnic Cohort (CMEC) study. Based on tertiles, the metal exposure can be divided into three groups: low, middle, and high exposure. Multivariate logistic regression models and principal component analysis were performed to determine exposure to single-metal and multi-metal co-exposure in relation to DM. A decrease in risk of DM was associated with iron (OR = 0.78, 95% CI: 0.61-1.00 and 0.68, 0.53-0.88 for the middle and high vs. low) and strontium (OR = 0.87, 95% CI: 0.69-1.12 and 0.67, 0.51-0.86 for the middle and high vs. low), respectively. A principal component 3 (PC3) characterized by iron and strontium showed an inverse association with DM. A principal component 4 (PC4) characterized by manganese and lead positively associated with DM. Exposure to high concentrations of urinary iron and strontium may reduce the risk of diabetes mellitus. This study revealed an increase in the risk of diabetes mellitus by co-exposure to high concentrations of urinary manganese and lead.

Lipid peroxidation mediates the association between iron overload and liver injury: cross-sectional and longitudinal analyses in general Chinese urban adults

Iron overload has been associated with acute/chronic organ failure, but whether iron overload induces liver injury remains unclear. The objectives of this study were to assess the relationship between urinary iron and serum alanine aminotransferase (ALT, a biomarker for liver injury), and investigate the potential mediating roles of lipid peroxidation and oxidative DNA damage in such association. Levels of urinary iron, serum ALT, and urinary biomarkers of lipid peroxidation (8-iso-prostaglandin-F_2α [8-iso-PGF_2α]) and oxidative DNA damage (8-hydroxy-deoxyguano-sine [8-OHdG]) were measured among 5386 observations of 4220 participants from the Wuhan-Zhuhai cohort. The relationships of urinary iron with serum ALT and risk of hyperALT were evaluated by linear mixed model and logistic regression model, respectively. The mediating roles of 8-iso-PGF_2α and 8-OHdG were assessed by mediation analyses. This cross-sectional analysis found that urinary iron was positively associated with ALT (β = 0.032; 95% CI: 0.020, 0.044) and hyperALT prevalence (OR = 1.127; 95% CI: 1.065, 1.192). After 3 years of follow-up, participants with persistent high iron levels had increased risk of developing hyperALT (RR = 3.800; 95% CI: 1.464, 9.972) when compared with those with persistent low iron levels. In addition, each 1% increase in urinary iron was associated with a 0.146% (95% CI: 0.128%, 0.164%) increase and a 0.192% (95% CI: 0.154%, 0.229%) increase in 8-iso-PGF_2α and 8-OHdG, respectively. Urinary 8-iso-PGF_2α (β = 0.056; 95% CI: 0.039, 0.074) was positively associated with ALT, while the association between 8-OHdG and ALT was insignificant. Furthermore, increased 8-iso-PGF_2α significantly mediated 22.48% of the urinary iron-associated ALT increment. Our study demonstrated that iron overload was significantly associated with liver injury, which was partly mediated by lipid peroxidation. Controlling iron intake and regulating lipid peroxidation may help in preventing liver injury.

Selenium exposure and urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine: Major effects of chemical species and sex

Selenium is an element present in trace amounts and different chemical forms. It may exert both beneficial and adverse effects on cellular redox status and on the generation of reactive oxygen species. 8-oxo-7,8-dihydro-2'deoxyguanosine (8-oxodG) is an oxidized derivative of deoxyguanosine, and a sensitive biomarker of oxidative stress and genotoxicity. The present study assessed the extent to which selenium status was associated with urinary 8-oxodG concentrations in a Northern Italian population. We recruited healthy, non-smoking blood donors living in the Reggio Emilia province during 2017-2019. We measured urinary 8-oxodG concentrations and used restricted cubic spline regression analyses to investigate the association between selenium status (estimated using food frequency questionnaires, urinary concentrations, and serum concentrations of selenium and selenium species) and 8-oxodG/g creatinine. Among 137 participants aged 30-60 years, median urinary selenium and 8-oxodG concentrations were 22.02 μg/L and 3.21 μg/g creatinine, respectively. Serum samples and selenium speciation analyses were available for 104 participants. Median total serum selenium levels and dietary intake were 116.5 μg/L and 78.7 μg/day, respectively. In spline regression analysis, there was little association between dietary, serum, or urinary selenium with 8-oxodG concentrations. In sex-specific analyses, urinary selenium showed a positive association with the endpoint among males. For single selenium species, we observed positive associations with urinary 8-oxodG for serum organic selenium species, and negative associations for inorganic selenium forms. In the most adjusted analysis, urinary 8-oxodG concentrations showed a strong positive association with selenomethione-bound selenium (Se-Met) and a negative association with inorganic tetravalent selenium, selenite. In sex-specific analyses, these associations were considerably stronger in males than in females. Overall, study findings indicate that selenium species exhibited very different patterns of associations with the biomarker of oxidative stress, and that these associations also depended on sex. Background exposure to Se-Met appears to be strongly and positively associated with oxidative stress.

Associations of metals and metals mixture with lipid profiles: A repeated-measures study of older adults in Beijing

Metals inevitably and easily enter into human bodies and can induce a series of pathophysiological changes, such as oxidative stress damage and lipid peroxidation, which then may further induce dyslipidemia. However, the effects of metals and metals mixture on the lipid profiles are still unclear, especially in older adults. A three-visits repeated measurement of 201 older adults in Beijing was conducted from November 2016 to January 2018. Linear Mixed Effects models and Bayesian kernel machine regression models were used to estimate associations of eight blood metals and metals mixture with lipid profiles, including total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), Castelli risk indexes I (CRI-1), Castelli risk indexes II (CRI-2), atherogenic coefficient (AC), and non-HDL cholesterol (NHC). Cesium (Cs) was positively associated with TG (β_Cs = 0.14; 95% CI: 0.02, 0.26) whereas copper (Cu) was inversely related to TG (β_Cu = -0.65; 95%CI: -1.14, -0.17) in adjusted models. Manganese (Mn) was mainly related to higher HDL-C (β_Mn = 0.14; 95% CI: 0.07, 0.21) whereas molybdenum showed opposite association. Metals mixture was marginally positive associated with HDL-C, among which Mn played a crucial role. Our findings suggest that the effects of single metal on lipid profiles may be counteracted in mixtures in the context of multiple metal exposures; however, future studies with large sample size are still needed to focus on the detrimental effects of single metals on lipid profiles as well as to identify key components.

Use of zinc nanoparticles and/or prodigiosin to mitigate heat stress in rabbits

Heat stress (HS) is an environmental challenge affecting animals' health, productivity and welfare. This work aimed to inspect the protective effect of zinc oxide nanoparticles (ZnNPs) and/or prodigiosin (PRG) against inflammation, immune dysfunction, oxidative stress and endoplasmic reticulum (ER) stress triggered by HS in growing rabbits. Growing weaned rabbits (one hundred males, 35 days of age) were randomly assigned into four groups. The first group fed a basal diet without supplementation and the 2nd, 3rd, and 4th groups fed diets containing zinc oxide nanoparticles (ZnNPs, 50mg/kg diet), prodigiosin (PRG, 100 mg/kg diet) or their mixture (ZnPRG) under HS conditions for eight successive weeks. The dietary inclusion with ZnNPs and/or PRG significantly boosted FBW (final body weight), CBWG (cumulative body weight gain), and FCR (feed conversion ratio) and had no substantial impacts on the CFI (cumulative feed intake) as compared with those in HS one. All supplemented treatments significantly unveiled an increase in the values of RBCs, hemoglobin, and platelets and significantly decreased in WBCs, basophils and monocytes with non-statistically effects on hematocrit, MCV, MCHC, neutrophils and eosinophils. Compared with the HS group, all supplemental groups showed a significant reduction in TNFα, IL4, IFN-γ, TLR-4 and amyloid A levels and DNA damage markers (Ohdg) and significantly increased in the levels of NO and lysosome activity. Rabbits in the ZnPRG group had significantly higher Ig G and Ig M levels than in other groups. The highest value of CAT and GSH levels were found in rabbits received the mixture of ZnNPs (50mg) and PRG (100mg) in their diets under elevated temperatures. Additionally, both treatments, PRG and ZnNPS, significantly (P<0.001) reduced the values of MDA and MYO, while all treated groups had significantly reduced PC contents compared with the HS group. Co-supplement with ZnPRG showed a considerable restoration in the higher immune expression of reticulum oxidative such GRP78 and IRE1 in hepatic tissues induced by HS conditions. The mixture of ZnNPs and PRG presented more robust effects in mitigating the adverse impacts of HS in rabbits compared with the individual treatments. Collectively, ZnNPs and/or PRG alleviated oxidative stress and DNA damage. In addition, it enhanced the antioxidant capacity and immune function, and downregulated ER stress such as GRP78 and IRE1 signaling in the hepatic tissues of stressed rabbits.

Relationships Between Urinary Metals and Diabetes Traits Among Mexican Americans in Starr County, Texas, USA

Hispanics/Latinos have higher rates of type 2 diabetes (T2D), and the origins of these disparities are poorly understood. Environmental endocrine-disrupting chemicals (EDCs), including some metals and metalloids, are implicated as diabetes risk factors. Data indicate that Hispanics/Latinos may be disproportionately exposed to EDCs, yet they remain understudied with respect to environmental exposures and diabetes. The objective of this study is to determine how metal exposures contribute to T2D progression by evaluating the associations between 8 urinary metals and measures of glycemic status in 414 normoglycemic or prediabetic adults living in Starr County, Texas, a Hispanic/Latino community with high rates of diabetes and diabetes-associated mortality. We used multivariable linear regression to quantify the differences in homeostatic model assessments for pancreatic β-cell function, insulin resistance, and insulin sensitivity (HOMA-β, HOMA-IR, HOMA-S, respectively), plasma insulin, plasma glucose, and hemoglobin A1c (HbA1c) associated with increasing urinary metal concentrations. Quantile-based g-computation was utilized to assess mixture effects. After multivariable adjustment, urinary arsenic and molybdenum were associated with lower HOMA-β, HOMA-IR, and plasma insulin levels and higher HOMA-S. Additionally, higher urinary copper levels were associated with a reduced HOMA-β. Lastly, a higher concentration of the 8 metal mixtures was associated with lower HOMA-β, HOMA-IR, and plasma insulin levels as well as higher HOMA-S. Our data indicate that arsenic, molybdenum, copper, and this metal mixture are associated with alterations in measures of glucose homeostasis among non-diabetics in Starr County. This study is one of the first to comprehensively evaluate associations of urinary metals with glycemic measures in a high-risk Mexican American population.

Sex-specific and dose-response relationships of urinary cobalt and molybdenum levels with glucose levels and insulin resistance in U.S. adults

Growing studies have linked metal exposure to diabetes risk. However, these studies had inconsistent results. We used a multiple linear regression model to investigate the sex-specific and dose-response associations between urinary metals (cobalt (Co) and molybdenum (Mo)) and diabetes-related indicators (fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), homeostasis model assessment for insulin resistance (HOMA-IR), and insulin) in a cross-sectional study based on the United States National Health and Nutrition Examination Survey. The urinary metal concentrations of 1423 eligible individuals were stratified on the basis of the quartile distribution. Our results showed that the urinary Co level in males at the fourth quartile (Q4) was strongly correlated with increased FPG (β = 0.61, 95% CI: 0.17-1.04), HbA1c (β = 0.31, 95% CI: 0.09-0.54), insulin (β = 8.18, 95% CI: 2.84-13.52), and HOMA-IR (β = 3.42, 95% CI: 1.40-5.44) when compared with first quartile (Q1). High urinary Mo levels (Q4 vs. Q1) were associated with elevated FPG (β = 0.46, 95% CI: 0.17-0.75) and HbA1c (β = 0.27, 95% CI: 0.11-0.42) in the overall population. Positive linear dose-response associations were observed between urinary Co and insulin (P_nonlinear = 0.513) and HOMA-IR (P_nonlinear = 0.736) in males, as well as a positive linear dose-response relationship between urinary Mo and FPG (P_nonlinear = 0.826) and HbA1c (P_nonlinear = 0.376) in the overall population. Significant sex-specific and dose-response relationships were observed between urinary metals (Co and Mo) and diabetes-related indicators, and the potential mechanisms should be further investigated.

Plasma microRNA expression profiles associated with zinc exposure and type 2 diabetes mellitus: Exploring potential role of miR-144-3p in zinc-induced insulin resistance

Zinc exposure has been linked with disordered glucose metabolism and type 2 diabetes mellitus (T2DM) development. However, the underlying mechanism remains unclear. We conducted population-based studies and in vitro experiments to explore potential role of microRNAs (miRNAs) in zinc-related hyperglycemia and T2DM. In the discovery stage, we identified plasma miRNAs expression profile for zinc exposure based on 87 community residents from the Wuhan-Zhuhai cohort through next-generation sequencing. MiRNAs profiling for T2DM was also performed among 9 pairs newly diagnosed T2DM-healthy controls. In the validating stage, plasma miRNA related to both of zinc exposure and T2DM among the discovery population was measured by qRT-PCR in 161 general individuals derived from the same cohort. Furthermore, zinc treated HepG2 cells with mimic or inhibitor were used to verify the regulating role of miR-144-3p. Based on the discovery and validating populations, we observed that miR-144-3p was positively associated with urinary zinc, hyperglycemia, and risk of T2DM. In vitro experiments confirmed that zinc-induced increase in miR-144-3p expression suppressed the target gene Nrf2 and downstream antioxidant enzymes, and aggravated insulin resistance. Our findings provided a novel clue for mechanism underlying zinc-induced glucose dysmetabolism and T2DM development, emphasizing the important role of miR-144-3p dysregulation.

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.

Cross-sectional and longitudinal relationships between urinary 1-bromopropane metabolite and pulmonary function and underlying role of oxidative damage among urban adults in the Wuhan-Zhuhai cohort in China

1-bromopropane is a US Environmental Protection Agency-identified significant hazardous air pollutant with concerned adverse respiratory effect. We aimed to investigate the relationship between 1-bromopropane exposure and pulmonary function and the underlying role of oxidative damage, which all remain unknown. Pulmonary function and urinary biomarkers of 1-bromopropane exposure (N-Acetyl-S-(n-propyl)-L-cysteine, BPMA) and oxidative damage to DNA (8-hydroxy-deoxyguanosine, 8-OHdG) and lipid (8-iso-prostaglandin-F2α, 8-iso-PGF2α) were measured for 3259 Chinese urban adults from the Wuhan-Zhuhai cohort. The cross-sectional relationship of BPMA with pulmonary function and the joint relationship of BPMA and 8-OHdG or 8-iso-PGF2α with pulmonary function were investigated by linear mixed models. The mediating roles of 8-OHdG and 8-iso-PGF2α were evaluated by mediation analysis. Additionally, a panel of 138 subjects was randomly convened from the same cohort to evaluate the stability of BPMA repeatedly measured in urine samples collected over consecutive three days and intervals of one, two, and three years, and to estimate the longitudinal relationship of BPMA with pulmonary function change in three years. We found each 3-fold increase in BPMA was cross-sectionally related to FVC and FEV₁ reductions by 29.88-mL and 25.67-mL, respectively (all P < 0.05). Joint relationship of BPMA and 8-OHdG rather than 8-iso-PGF2α with reduced pulmonary function was observed. Moreover, 8-OHdG significantly mediated 9.44% of the BPMA-related FVC reduction. Findings from the panel revealed a fair to excellent stability (intraclass correlation coefficient: 0.43-0.79) of BPMA in repeated urines collected over a period of three years. Besides, BPMA was longitudinally related to pulmonary function reduction in three years: compared with subjects with persistently low BPMA level, those with persistently high BPMA level had 79.08-mL/year and 49.80-mL/year declines in FVC and FEV₁, respectively (all P < 0.05). Conclusively, 1-bromopropane exposure might impair pulmonary function of urban adult population, and oxidative DNA damage might be a potential mechanism underlying 1-bromopropane impairing pulmonary function especially FVC.

Exposure to lead and cadmium is associated with fasting plasma glucose and type 2 diabetes in Chinese adults

AIMS

Exposure to lead and cadmium has been associated with type 2 diabetes, but the results are largely inconsistent, and little is known about their joint effect. We aimed to investigate the associations of lead and cadmium co-exposure with fasting plasma glucose (FPG) and type 2 diabetes.

MATERIALS AND METHODS

The study included 5732 participants aged ≥18 years from 16 communities in East China. Blood levels of lead and cadmium were determined using graphite furnace atomic absorption spectrometry. Multivariable linear and logistic regression models were performed to evaluate the associations of lead and cadmium alone or in combination with FPG and diabetes.

RESULTS

The median (interquartile range) values of blood lead and cadmium were 40.0 (26.8-57.9) and 1.70 (0.56-3.60) μg/L, respectively. After adjustment for potential confounders, blood lead levels were positively associated with FPG (difference comparing extreme lead quartiles = 0.11 [95% CI: 0.03, 0.20] mmol/L) and prevalent diabetes (odds ratio [OR] = 1.35 [95% CI: 1.03, 1.78]). The association between lead and diabetes was observed among participants with high cadmium, but not among those with low cadmium (P for interaction = 0.03). In the joint analysis, compared with participants with low levels of blood lead and cadmium, participants with high levels of two metals had a 0.16 (95% CI: 0.07, 0.25) mmol/L increase in FPG and a 51% (OR = 1.51, 95% CI: 1.15, 1.99) increase in odds of diabetes.

CONCLUSIONS

Our findings suggest that lead and cadmium co-exposure is significantly associated with elevated FPG and type 2 diabetes in the general population.

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.

Lead exposure and impaired glucose homeostasis in Chinese adults: A repeated measures study with 5 years of follow-up

Experimental studies suggest the diabetogenic effects of lead, but relevant data in humans are limited and have been primarily based on cross-sectional study design. We aimed to prospectively examine the association between lead exposure and glucose homeostasis in general population using repeated measurements. This cohort study included 5505 Chinese adults free of glucose-lowering medication use at baseline in 2014 and followed up 5 years later. Blood lead and glucose metabolic traits including fasting plasma glucose (FPG), fasting serum insulin, the homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA of beta-cell function (HOMA-B) were measured at baseline and follow-up. Linear mixed models and linear regression models were performed to evaluate the associations between blood lead and markers of glucose homeostasis. After full adjustment for confounders including BMI, an interquartile range (IQR) increase in blood lead levels was associated with a 2.26 % increase in FPG (95 % CI: 0.16 %, 4.39 %) and an 11.3 % decrease in HOMA-B (95 % CI: - 19.1 %, - 2.71 %) in women. The odds ratios of hyperglycemia and beta-cell dysfunction corresponding to an IQR increase in blood lead levels were 1.39 (95 % CI: 0.99, 1.95) and 1.74 (95 % CI: 1.00, 3.03), respectively. Similar results were found for 5-year changes of glucose metabolic markers. Compared with the first quartile of baseline lead levels, the highest lead quartile was associated with an additional 3.03 % increase in FPG (95 % CI: 0.84 %, 5.26 %) and an additional 13.3 % decrease in HOMA-B (95 % CI: - 20.4 %, - 5.53 %) in women during follow-up. We observed no overall associations between blood lead levels and glucose metabolic markers in men. Our findings provide suggestive evidence that environmental exposure to lead might contribute to sex-dependent disruption of glucose homeostasis in general adult population.

Associations of polychlorinated biphenyls exposure with plasma glucose and diabetes in general Chinese population: The mediating effect of lipid peroxidation

Polychlorinated biphenyls (PCBs) exposure has been related to the abnormal glucose metabolism and the risk of diabetes. However, the joint effects of various PCBs are uncertain and the potential mechanisms remain unclear. Our objectives were to evaluate the associations of serum PCBs with fasting plasma glucose (FPG) and the risk of diabetes among a general Chinese population, and to estimate the mediating effects of oxidative stress in the above associations. Serum levels of seven indicator-PCBs (PCB-28, 52, 101, 118, 138, 153, and 180) and FPG values were determined among 4498 subjects from the Wuhan-Zhuhai cohort. Oxidative DNA damage biomarker (urinary 8-hydroxy-2'-deoxyguanosine, 8-OHdG) and lipid peroxidation biomarker (urinary 8-isoprostane, 8-iso-PGF_2α) were also measured. Positive relationships of serum PCBs with FPG values as well as the risk of diabetes were observed. With each 1% increment in the natural log-transformed values of wet weight serum PCBs, FPG levels increased a 0.125% for PCB-52, 0.168% for PCB-118, 0.221% for PCB-138, 0.273% for PCB-153, and 0.379% for ΣPCB (the sum of seven PCBs). The adjusted odds ratios of diabetes associated with wet weight PCBs were 1.186 for PCB-52, 1.373 for PCB-118, 1.635 for PCB-153, and 1.456 for ΣPCB. The seven serum PCBs showed positive overall effect on the risk of diabetes. Elevated PCB-28, PCB-52, PCB-118, PCB-138, PCB-153, and ΣPCB were associated with the increased urinary 8-iso-PGF_2α, which was positively related with FPG values. Furthermore, urinary 8-iso-PGF_2α partially mediated the positive associations between PCBs and FPG values, with the mediated proportions ranged from 3.20 to 12.93%. In conclusion, our results suggested that serum PCBs were positively related with increased oxidative stress, FPG values, and the risk of diabetes among a general Chinese population. Serum PCBs mixture had positive overall effect on the risk of diabetes. Lipid peroxidation partly mediated the FPG elevation induced by PCB exposure.

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.

Associations of Heavy Metals with Activities of Daily Living Disability: An Epigenome-Wide View of DNA Methylation and Mediation Analysis

BACKGROUND

Exposure to heavy metals has been reported to be associated with multiple diseases. However, direct associations and potential mechanisms of heavy metals with physical disability remain unclear.

OBJECTIVES

We aimed to quantify associations of heavy metals with physical disability and further explore the potential mechanisms of DNA methylation on the genome scale.

METHODS

A cross-sectional study of 4,391 older adults was conducted and activities of daily living (ADL) disability were identified using a 14-item scale questionnaire including basic and instrumental activities to assess the presence of disability (yes or no) rated on a scale of dependence. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated to quantify associations between heavy metals and ADL disability prevalence using multivariate logistic regression and Bayesian kernel machine regression (BKMR) models. Whole blood-derived DNA methylation was measured using the HumanMethylationEPIC BeadChip array. An ADL disability-related epigenome-wide DNA methylation association study (EWAS) was performed among 212 sex-matched ADL disability cases and controls, and mediation analysis was further applied to explore potential mediators of DNA methylation.

RESULTS

Each 1-standard deviation (SD) higher difference in log10-transformed manganese, copper, arsenic, and cadmium level was significantly associated with a 14% (95% CI: 1.05, 1.24), 16% (95% CI:1.07, 1.26), 22% (95% CI:1.13, 1.33), and 15% (95% CI:1.06, 1.26) higher odds of ADL disability, which remained significant in the multiple-metal and BKMR models. A total of 85 differential DNA methylation sites were identified to be associated with ADL disability prevalence, among which methylation level at cg220000984 and cg23012519 (annotated to IRGM and PKP3) mediated 31.0% and 31.2% of manganese-associated ADL disability prevalence, cg06723863 (annotated to ESRP2) mediated 32.4% of copper-associated ADL disability prevalence, cg24433124 (nearest to IER3) mediated 15.8% of arsenic-associated ADL disability prevalence, and cg07905190 and cg17485717 (annotated to FREM1 and TCP11L1) mediated 21.5% and 30.5% of cadmium-associated ADL disability prevalence (all p<0.05).

DISCUSSION

Our findings suggested that heavy metals contributed to higher prevalence of ADL disability and that locus-specific DNA methylation are partial mediators, providing potential biomarkers for further cellular mechanism studies. https://doi.org/10.1289/EHP10602.

Acrylamide exposure increases cardiovascular risk of general adult population probably by inducing oxidative stress, inflammation, and TGF-β1: A prospective cohort study

Acrylamide (ACR) exposure and consequent health hazards are alarming public health issues that attract worldwide concern. The World Health Organization urges more researches into health hazards from ACR exposure. However, whether and how ACR exposure increases cardiovascular risk remain unclear, and we sought to address these issues in this prospective cohort study conducted on 3024 general adults with 3-year follow-up (N = 871 at follow-up). Individual urinary ACR metabolites (N-Acetyl-S-(2-carbamoylethyl)-L-cysteine [AAMA] and N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine [GAMA]) as credible biomarkers of ACR exposure were detected to assess their cross-sectional and longitudinal relationships with 10-year cardiovascular disease (CVD) risk, a well measure of overall cardiovascular risk. Besides, biomarkers of oxidative stress (urinary 8-hydroxy-deoxyguanosine [8-OHdG] and 8-iso-prostaglandin-F2α [8-iso-PGF2α]) and inflammation (circulating mean platelet volume [MPV] and plasma C-reactive protein [CRP]) as well as plasma transforming growth factor-β1 (TGF-β1) were measured to assess their mediating/mechanistic roles in the relationships of ACR metabolites with 10-year CVD risk. We found AAMA, GAMA, and ΣUAAM (AAMA + GAMA) were cross-sectionally and longitudinally related to increased 10-year CVD risk with odds ratios (95% confidence intervals [CIs]) of 1.32 (1.04, 1.70), 1.81 (1.36, 2.40), and 1.40 (1.07, 1.82), respectively, and risk ratios (95% CIs) of 1.99 (1.10, 3.60), 2.48 (1.27, 4.86), and 2.13 (1.15, 3.94), respectively. Furthermore, 8-OHdG, 8-iso-PGF2α, MPV, CRP, and TGF-β1 were found to significantly mediate 8.06-48.92% of the ACR metabolites-associated 10-year CVD risk increment. In summary, daily ACR exposure of general adults was cross-sectionally and longitudinally associated with increased cardiovascular risk, which was partly mediated by oxidative stress, inflammation, and TGF-β1, suggesting for the first time that ACR exposure may well increase cardiovascular risk of general adult population partly by mechanisms of inducing oxidative stress, inflammation, and TGF-β1. Our findings have important public health implications that provide potent epidemiological evidence and vital mechanistic insight into cardiovascular risk increment from ACR exposure.

Associations of urinary metabolites of oxidized DNA and RNA with the incidence of diabetes mellitus using UPLC-MS/MS and ELISA methods

BACKGROUND

To evaluate the association of urinary oxidized guanine/guanosine (OxGuo) levels with incident type 2 diabetes (T2D) among older adults.

METHODS

A nested case-control design was applied with 440 cases of incident T2D and 440 controls, randomly sampled from all 65-75 year-old study participants of the ESTHER study, which is a population-based German cohort study with 14 years of follow-up. Analyses of 8-hydroxy-2'-deoxyguanosine (8-oxo-dGuo; DNA oxidation product) and 8-hydroxyguanosine (8-oxo-Guo; RNA oxidation product) were measured by ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS). The sum of the two OxGuo molecule concentrations was calculated and called OxGuo-UPLC-MS/MS. The corresponding OxGuo-ELISA levels were measured by Cayman's DNA/RNA oxidative damage ELISA, which detects a mix of 8-oxo-dGuo, 8-oxo-Guo and one other OxGuo molecule. Logistic regression was applied and models were adjusted for age, sex, BMI, HbA_1c, and C-reactive protein levels.

RESULTS

8-oxo-dGuo and 8-oxo-Guo were highly correlated with each other (r = 0.642) and weakly correlated with OxGuo-ELISA (r = 0.22 and r = 0.14, respectively). OxGuo-ELISA levels were statistically significant associated with T2D incidence (odds ratio (OR) and 95% confidence interval [95%CI] for comparison of top and bottom quartile: 1.77 [1.14; 2.76]). In contrast, the ORs did not increase stepwise from quartile 2 to 4 for neither 8-oxo-Guo, 8-oxo-dGuo levels nor OxGuo-UPLC-MS/MS and comparisons of top and bottom quartile were not statistically significant. In a post-hoc analysis comparing bottom quartile 1 with a combined group of quartile 2-4, the association of OxGuo-UPLC-MS/MS with T2D incidence reached statistical significance (OR [95%CI]: 0.66 [0.46; 0.96]) and was very similar with the one obtained for OxGuo-ELISA (OR [95%CI]: 0.66 [0.45; 0.95]).

CONCLUSIONS

Although only the measurements of the DNA/RNA oxidative damage ELISA kit of Cayman were statistically significantly associated with T2D incidence in the main analysis, confidence intervals overlapped and the post-hoc analysis showed that results for OxGuo-UPLC-MS/MS were quite comparable.

Interactions of antimony with biomolecules and its effects on human health

Antimony (Sb) pollution has increased health risks to humans as a result of extensive application in diverse fields. Exposure to different levels of Sb and its compounds will directly or indirectly affect the normal function of the human body, whereas limited human health data and simulation studies delay the understanding of this element. In this review, we summarize current research on the effects of Sb on human health from different perspectives. First, the exposure pathways, concentration and excretion of Sb in humans are briefly introduced, and several studies have revealed that human exposure to high levels of Sb will cause higher concentrations in body tissues. Second, interactions between Sb and biomolecules or other nonbiomolecules affected biochemical processes such as gene expression and hormone secretion, which are vital for causing and understanding health effects and mechanisms. Finally, we discuss the different health effects of Sb at the biological level from small molecules to individual. In conclusion, exposure to high levels of Sb compounds will increase the risk of disease by affecting different cell signaling pathways. In addition, the appropriate form and dose of Sb contribute to inhibit the development of specific diseases. Key challenges and gaps in toxicity or benefit effects and mechanisms that still hinder risk assessment of human health are also identified in this review. Systematic studies on the relationships between the biochemical process of Sb and human health are needed.

Combined effects of exposure to polycyclic aromatic hydrocarbons and metals on oxidative stress among healthy adults in Caofeidian, China

Exposure to polycyclic aromatic hydrocarbons (PAHs) and metals is associated with many adverse effects on human health, accompanied by oxidative stress. This study aimed to investigate the effects of co-exposure to PAHs and metals on oxidative stress in healthy adults. A preliminary longitudinal panel study was conducted between 2017 and 2018 in 45 healthy college students in Caofeidian, China. Six urinary monohydroxylated-PAHs (OH-PAHs), ten metals, 8-hydroxydeoxyguanosine (8-OHdG), and 8-iso-prostaglandin-F2α (8-iso-PGF2α) were measured. Linear mixed effects (LME) models and Bayesian kernel machine regression (BKMR) models were used to explore the associations of urinary OH-PAHs and metals with 8-OHdG and 8-iso-PGF2α. LME models showed that most urinary OH-PAHs and metals were positively associated with 8-OHdG and 8-iso-PGF2α. For example, a one-unit increase in the ln-transformed level of 1-hydroxypyrene (1-OHPyr) and vanadium (V) was associated with an increase of 143.8% (95% CI: 105.7 - 188.9%) and 105.8% (95% CI: 79.2-136.4%) in 8-OHdG; 8-iso-PGF2α increased by 118.9% (95% CI: 99.2-140.5%) and 83.9% (95% CI: 67.2-102.2%) with a one-unit increase in the ln-transformed level of 3-hydroxyphenanthrene (3-OHPhe) and aluminum (Al). BKMR models indicated the overall positive associations of the mixture of six OH-PAHs, ten metals, or six OH-PAHs and ten metals with 8-OHdG and 8-iso-PGF2α. Urinary 1-OHPyr and V were identified as the major contributors to the increased urinary 8-OHdG levels, while urinary 3-OHPhe and Al were the most vital contributors to the increased urinary 8-iso-PGF2α levels. The results revealed the longitudinal dose-response relationships of urinary OH-PAHs and metals with oxidative stress among healthy adults in Caofeidian; this finding serves as an evidence regarding the early health hazard caused by exposure to PAHs and metals and has implications for the environmental management of PAH and metal emissions in this area.

Associations of propylene oxide exposure with fasting plasma glucose and diabetes: Roles of oxidative DNA damage and lipid peroxidation

Whether propylene oxide (PO) exposure is associated with hyperglycemia were rarely explored. We aimed to determine the relationship between PO exposure and glucose metabolism, and potential role of oxidative stress. Among 3294 Chinese urban adults, urinary PO metabolite (N-Acetyl-S-(2-hydroxypropyl)-L-cysteine, 2HPMA), biomarkers of oxidative DNA damage (8-oxo-7,8-dihydro-20-deoxyguanosine, 8-OHdG) and lipid peroxidation (8-isoprostane, 8-iso-PGF_2α) in urine were determined. The associations of 2HPMA with 8-OHdG, 8-iso-PGF_2α, fasting plasma glucose (FPG), and risk of diabetes were explored. The roles of 8-OHdG and 8-iso-PGF_2α on association of 2HPMA with FPG and risk of diabetes were detected. After adjusted for potential confounders, each 1-unit increase in log-transformed concentration of 2HPMA was associated with a 0.15-mmol/L increase in FPG level, and the adjusted OR (95% CI) of diabetes by the associations of log-transformed urinary 2HPMA concentrations was 1.47 (95% CI: 1.03-2.11). Combination effects of 2HPMA with 8-OHdG or 8-iso-PGF_2α on risk of diabetes were detected, and elevated 8-iso-PGF_2α significantly mediated 34.5% of the urinary 2HPMA-associated FPG elevation. PO exposure was positively associated with FPG levels and risk of diabetes. PO exposure combined with DNA oxidative damage or lipid peroxidation may increase the risk of diabetes, and lipid peroxidation may partially mediate the PO exposure-induced FPG elevation.

Urinary Transferrin and Proinflammatory Markers Predict the Earliest Diabetic Nephropathy Onset

This study aimed to determine the earliest markers of diabetic nephropathy (DN) onset with discriminative potentials from controlled diabetes (CD). Methods: Sixty male Wistar rats were allocated in three groups (20/group), the two diabetic groups CD and DN received 45 and 65 mg/kg STZ in 0.1 mole/L citrate buffer; respectively, while control group received only the vehicle. Serum/urinary levels of glomerular, tubular, oxidative and proinflammatory markers were weekly monitored. Results: Each diabetic group showed a different pattern of inflammatory; oxidative and signs of nephropathy along the study period, but none had a discriminative power until the 4^th week. At this time point, levels of urinary transferrin; serum/urinary IL-6 and TNF-α as well as urinary IL-18 were significantly higher in DN group comparing to CD (P = 0.0217, <0.0001, 0.0005, 0.0004, 0.0006, 0.0019; respectively). Predictive thresholds of these markers were calculated by receiver operating characteristic (ROC) curve that showed area under curve (AUC) of 0.9375 for transferrin with cut-off value 35.2 mg/dL, and 1.000 for serum/urinary IL-6 and TNF-α and urinary IL-18 with cut-of values 224.1, 82.11, 6.596, 125.9 and 21.86 pg/mL; respectively. Conclusion: Urinary transferrin and the inflammatory endpoints proposed in this study might represent promising biomarkers for the early DN onset.

Inverse Association of Plasma Molybdenum with Metabolic Syndrome in a Chinese Adult Population: A Case-Control Study

Molybdenum has been found to be associated with metabolic disorders. However, the relationship between molybdenum and metabolic syndrome (MetS) is still unclear. A large case-control study was conducted in a Chinese population from the baseline of Ezhou-Shenzhen cohort. A total of 5356 subjects were included with 2678 MetS and 2678 controls matched by sex and age (±2 years). Medians (IQRs) of plasma molybdenum concentrations were 1.24 μg/L for MetS cases and 1.46 μg/L for controls. After adjustment for multiple covariates, the odds ratio (OR) and 95% confidence intervals (CIs) for MetS were 1.00 (reference), 0.71 (0.59-0.84), 0.56 (0.46-0.68), and 0.47 (0.39-0.58) across quartiles of plasma molybdenum, and per SD increment of log-transformed molybdenum was associated with a 23% lower risk of MetS. In the spline analysis, the risk of MetS and its components decreased steeply with increasing molybdenum and followed by a plateau when the cutoff point was observed around 2.0 μg/L. The dose-dependent relationship of molybdenum with MetS remained consistent when considering other essential elements in the Bayesian kernel machine regression (BKMR) model. In our study, higher plasma molybdenum was significantly associated with a lower risk of MetS, as well as its components, in a dose-response manner.

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.

Effects of polycyclic aromatic hydrocarbons and multiple metals co-exposure on the mosaic loss of chromosome Y in peripheral blood

Mosaic loss of chromosome Y (mLOY) is an indicator of genome instability, but the environmental stressors of mLOY remained largely unknown. In this study, we detected the internal exposure levels of 11 polycyclic aromatic hydrocarbon (PAH) metabolites and 22 metals among 888 coke-oven workers, and calculated their blood mLOY based on genome-wide SNP genotyping data and presented as median log R ratio (mLRR-Y). The generalized linear model (GLM), LASSO, and Bayesian kernel machine regression (BKMR), were used to select mLOY-relevant chemicals. The results of these models consistently suggested the negative dose-response relationships of urinary 1-hydroxynaphthalene (1-OHNa), antimony (Sb), and molybdenum (Mo) with mLRR-Y. There were no pairwise interactions between these three chemicals (P_interaction > 0.05), but subjects with high exposure to ≥ 2 kinds of these chemicals showed reducing mLRR-Y [β(95%CI) = - 0.015(- 0.023, - 0.008)], increasing oxidative DNA damage (marked by 8-hydroxydeoxyguanosine) [β(95%CI) = 0.625(0.454, 0.796)] and chromosome damage (marked by micronucleus frequency in lymphocytes) [frequency ratio (FR) and 95%CI = 1.146(1.047, 1.225)] than those with low exposure to all these chemicals. The combined effects of 1-OHNa, Sb, and Mo on elevating DNA damage may partly explain their joint effects on increased blood mLOY. These results provided a new insight into environmental hazards co-exposure on chromosome-Y deletions.

A systematic review and dose-response meta-analysis of exposure to environmental selenium and the risk of type 2 diabetes in nonexperimental studies

Accumulating evidence from both experimental and nonexperimental human studies in the last 15 years indicates that exposure to high levels of the trace element selenium increases the risk of type 2 diabetes. However, the relation of dose to effect is not well understood because randomized controlled trials used only one dose (200 μg/day) of selenium supplementation. While no new trial on this topic has been published since 2018, several nonexperimental studies have appeared. We therefore updated a previous meta-analysis to include recently published observational studies, and incorporated the recently developed one-stage random-effects model to display the dose-response relation between selenium and type 2 diabetes. We retrieved 34 potentially eligible nonexperimental studies on selenium and diabetes risk up to April 15, 2021. The bulk of the evidence indicates a direct relation between blood, dietary and urinary levels of selenium and risk of diabetes, but not with nail selenium, which may be considered a less reliable biomarker. The association was nonlinear, with risk increasing above 80 μg/day of dietary selenium. Whole blood/plasma/serum selenium concentrations of 160 μg/L corresponded to a risk ratio of 1.96 (95% CI 1.27-3.03) compared with a concentration of 90 μg/L (approximately 60 μg of daily selenium intake). The cohort studies, which are less susceptible to reverse causation bias, indicated increased risk for both blood and urine selenium levels and dietary selenium intake, whereas no such pattern emerged from studies relying on nail selenium content. Overall, the nonexperimental studies agree with findings from randomized controlled trials, indicating that moderate to high levels of selenium exposure are associated with increased risk for type 2 diabetes.

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.

Concentrations of vanadium in urine with hypertension prevalence and blood pressure levels

The associations of vanadium exposure with hypertension risk in animal studies are inconsistent. Furthermore, epidemiologic studies on this topic are scarce. We aimed to assess the associations of vanadium exposure with hypertension prevalence and blood pressure levels in a general Chinese population. We measured urinary vanadium concentrations in 1867 participants to evaluate their internal exposure levels. The associations of urinary vanadium concentrations, categorized into quartiles or treated as continuous variables by logarithm transformation (log2), with hypertension prevalence and blood pressure levels were assessed by the multivariable logistic and linear regression models, respectively. We used the restricted cubic spline model to evaluate the dose-response relationship. Compared with the bottom quartile of vanadium, participants in the third and fourth quartile had an adjusted odds ratio of 2.04 (95% CI:1.40, 2.96) and 2.08 (95% CI:1.42, 3.06) for hypertension, with a linear dose-response relationship. The corresponding number for a doubling of vanadium concentrations was 1.25 (95% CI:1.12, 1.39). Besides, a doubling of vanadium concentrations was associated with a 0.66 (95% CI: 0.01, 1.31) and 0.90 (95% CI: 0.50, 1.31) mm Hg increased systolic and diastolic blood pressure level, respectively. Vanadium exposure was associated with increased hypertension prevalence and blood pressure levels. Prospective studies are needed to confirm our findings in other populations.

Sex-specific associations of plasma metals and metal mixtures with glucose metabolism: An occupational population-based study in China

Studies with multi-pollutant approach on the relationships between multiple metals and fasting plasma glucose (FPG) are limited. Few studies are available on the potential sex-specific associations between metal exposures and glucose metabolism. We explored the associations between 22 plasma metals and FPG level among the 769 participants from the manganese-exposed workers healthy cohort in China. We applied a sparse partial least squares (sPLS) regression followed by ordinary least-squares regression to evaluate multi-pollutant association. Bayesian kernel machine regression (BKMR) model was used to deal with metal mixtures and evaluate their joint effects on FPG level. In the sPLS model, negative associations on FPG levels were observed for plasma iron (belta = -0.066), cobalt (belta = -0.075), barium (belta = -0.109), and positive associations for strontium (belta = 0.082), and selenium (belta = 0.057) in men, which overlapped with the results among the overall participants. Among women, plasma copper (belta = 0.112) and antimony (belta = 0.137) were positively associated with elevated FPG level. Plasma magnesium was negatively associated with FPG level in both sexes (belta = -0.071 in men and belta = -0.144 in women). The results of overlapped for plasma magnesium was selected as the significant contributor to decreasing FPG level in the multi-pollutant, single-metal, and multi-metal models. BKMR model showed a significantly negative over-all effect of six metal mixtures (magnesium, iron, cobalt, selenium, strontium and barium) on FPG level among the overall participants from all the metals fixed at 50th percentile. In summary, our findings underline the probable role of metals in glucose homeostasis with potential sex-dependent heterogeneities, and suggest more researches are needed to explore the sex-specific associations of metal exposures with risk of diabetes.

Associations between metabolic syndrome and four heavy metals: A systematic review and meta-analysis

Four most concerned heavy metal pollutants, arsenic, cadmium, lead, and mercury may share common mechanisms to induce metabolic syndrome (MetS). However, recent studies exploring the relationships between MetS and metal exposure presented inconsistent findings. We aimed to clarify the relationship between heavy metal exposure biomarkers and MetS using a meta-analysis and systematic review approach. Literature search was conducted in international and the Chinese national databases up to June 2020. Of selected studies, we extracted the relevant data and evaluated the quality of each study's methodology. We then calculated the pooled effect sizes (ESs), standardized mean differences (SMDs), and their 95% confidence intervals (CIs) using a random-effect meta-analysis approach followed by stratification analyses for control of potential confounders. Involving 55,536 participants, the included 22 articles covered 52 observational studies reporting ESs and/or metal concentrations on specific metal and gender. Our results show that participants with MetS had significantly higher levels of heavy metal exposure [pooled ES = 1.16, 95% CI: 1.09, 1.23; n = 42, heterogeneity I2 = 75.6%; and SMD = 0.22, 95% CI: 0.15, 0.29; n = 32, I2 = 94.2%] than those without MetS. Pooled ESs in the subgroups stratified by arsenic, cadmium, lead, and mercury were 1.04 (95% CI: 0.97, 1.10; n = 8, I2 = 61.0%), 1.10 (0.95, 1.27; 11, 45.0%), 1.21 (1.00, 1.48; 12, 82.9%), and 1.26 (1.06, 1.48; 11, 67.7%), respectively. Pooled ESs in the subgroups stratified by blood, urine, and the other specimen were 1.22 (95% CI: 1.08, 1.38; n = 26, I2 = 75.8%), 1.06 (1.00, 1.13; 14, 58.1%), and 2.41 (1.30, 4.43; 2, 0.0%), respectively. In conclusion, heavy metal exposure was positively associated with MetS. Further studies are warranted to examine the effects of individual metals and their interaction on the relationship between MetS and heavy metals.

IL-22: A potential mediator of associations between urinary polycyclic aromatic hydrocarbon metabolites with fasting plasma glucose and type 2 diabetes

Previous studies found that exposure to polycyclic aromatic hydrocarbons (PAHs) was associated with type 2 diabetes (T2D) prevalence. However, the potential mechanism is still unclear. In this study, we investigated 3031 Chinese urban adults to discover the relationship between PAH exposure and plasma Interleukin-22 (IL-22) and potential role of IL-22 in the association between PAH and fasting plasma glucose (FPG) or risk of T2D. After adjustment for potential confounders, significant dose-response relationships were observed between several urinary PAH metabolites with FPG and the prevalence of T2D. Each 1-U increase in ln-transformed value of 2-hydroxynaphthalene (2-OHNa), 2-hydroxyphenanthrene (2-OHPh), 3-hydroxyphenanthrene (3-OHPh), 4-hydroxyphenanthrene (4-OHPh), 9-hydroxyphenanthrene (9-OHPh), 1-hydroxypyrene (1-OHP) or total PAH metabolites was significantly associated with a 0.053, 0.026, 0.037, 0.045, 0.051, 0.041 or 0.047 unit decrease in IL-22 level, respectively. In addition, plasma IL-22 level was negatively associated with FPG and prevalence of T2D in a dose-dependent manner. Mediation analysis showed that IL-22 mediated 8.48 %, 3.87 %, 6.64 %, 6.47 %, and 8.67 % of the associations between urinary 2-OHNa, 1-OHPh, 3-OHPh, 4-OHPh, and 9-OHPh with the prevalence of T2D, respectively. These results indicated that urinary PAHs metabolites were inversely associated with plasma levels of IL-22, but positively related to FPG and the T2D prevalence. Downregulation of IL-22 might play a significant role in mediating PAHs exposure-associated risk increasement of T2D.

Cadmium exposure, fasting blood glucose changes, and type 2 diabetes mellitus: A longitudinal prospective study in China

BACKGROUND

Cadmium is a recognized human carcinogen, raising global concern for its ubiquitously environmental exposure on public health. Diabetogenic effects of cadmium have been suggested in previous studies, but the longitudinal associations of chronic cadmium exposure with fasting blood glucose changes and type 2 diabetes mellitus have not been fully elucidated.

OBJECTIVE

To investigate the effects of long-term cadmium exposure on the fasting blood glucose changes and type 2 diabetes mellitus risk in a longitudinal prospective study of China.

METHODS

A total of 3521 urban adults were included as baseline study population from the Wuhan-Zhuhai cohort, and followed up three years later. Urinary cadmium concentrations were determined repeatedly during the follow-up of a three-year period. The within-person and between-person variability of urinary cadmium concentrations over three years was estimated using multilevel random-effects mixed models. Multivariate regression models were performed to evaluate the associations of cadmium exposure with fasting blood glucose changes and type 2 diabetes mellitus risk.

RESULTS

The geometric means of creatinine-corrected urinary cadmium concentration at baseline were 1.13 μg/g creatinine, which were close to the levels of follow-up (1.14 μg/g creatinine). The intra-class correlation coefficient of creatinine-corrected urinary cadmium concentrations was 0.71, achieving good reproducibility of cadmium over three years. With adjustment for potential confounders, each one-unit increase in log10-transformed cadmium was associated with a 0.11 (95%CI: 0.03 to 0.19) elevation in fasting blood glucose concentration, and was associated with a 42% (95%CI: 1.16 to 1.73) increase in risk of prevalent type 2 diabetes mellitus. Upward trends of fasting blood glucose changes and type 2 diabetes mellitus incidence were observed with increasing cadmium exposure. Individuals with the highest urinary cadmium exposure had a significant increase in fasting blood glucose change at follow-up [β (95% CI): 0.49 (0.31-0.67)]. Risk of incident type 2 diabetes mellitus were gradually elevated across increasing quartiles of cadmium exposure, though associations did not reach statistical significance (P = 0.15).

CONCLUSIONS

Our findings suggested that relatively high chronic cadmium exposure for general population adults might contribute to elevated changes of fasting blood glucose resulting in the development of type 2 diabetes mellitus.

Heavy metals exposure, lipid peroxidation and heart rate variability alteration: Association and mediation analyses in urban adults

Exposure to heavy metals was reported to be associated with heart rate variability (HRV) alteration. However, possible pathway of such association remains unclear. In this research, we investigated the possible role of lipid peroxidation in the associations between urinary heavy metals and HRV. We performed a cross-sectional study using baseline data of Wuhan-Zhuhai cohort. Urinary heavy metals (including lead, barium, antimony, cadmium, zinc, copper, iron and manganese), urinary 8-iso-prostaglandin-F2α levels (common biomarker for lipid peroxidation) and HRV indices (SDNN, r-MSSD, low frequency, high frequency and total power) were measured among 3022 participants. We conducted multivariable linear regression models to quantify associations between urinary 8-iso-prostaglandin-F2α (8-iso-PGF2α) and heavy metals or HRV indices. The potential role of 8-iso-PGF2α in the association of urinary heavy metals with HRV was evaluated through mediation analyses. After adjusting for potential confounders, urinary manganese, iron, copper, zinc, cadmium, antimony and barium were identified to be negatively associated with one or more HRV parameters. Each one-unit growth of log-transformed levels of urinary manganese, iron, copper, zinc, antimony and barium was associated with a 1.9%, 1.5%, 4.7%, 4.0%, 2.7% and 1.3% decrease in SDNN, respectively. We observed positive dose-response relationships between all eight urinary heavy metals and 8-iso-PGF2α, as well as negative association of urinary 8-iso-PGF2α with SDNN and total power (all P trend<0.05). The proportions mediated by 8-iso-PGF2α on SDNN were 4.6% for manganese, 9.3% for iron, 19.8% for antimony and 11.0% for barium. The proportions mediated by 8-iso-PGF2α on total power were 6.9% for manganese and 10.1% for cadmium (all P value < 0.05). This study suggested that urinary manganese, iron, copper, zinc, cadmium, antimony and barium were negatively associated with HRV indices. Lipid peroxidation may partly mediate the associations of urinary manganese, iron, cadmium, antimony and barium with specific HRV indices.

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

Background

Exposure to zinc was suggested to be associated with pulmonary damage, but whether zinc exposure affects lung function remains unclear.

Objectives

To quantify the association between urinary zinc and lung function and explore the potential mechanisms.

Methods

Urinary zinc and lung function were measured in 3917 adults from the Wuhan-Zhuhai cohort and were repeated after 3 years of follow-up. Indicators of systemic inflammation (C reactive protein), lung epithelium integrity (club cell secretory protein-16) and oxidative damage (8-hydroxy-2′-deoxyguanosine and 8-isoprostane) were measured at baseline. Linear mixed models were used to estimate the exposure–response relationship between urinary zinc and lung function. Mediation analyses were conducted to assess mediating roles of inflammation and oxidative damage in above relationships.

Results

Each 1-unit increase in log-transformed urinary zinc values was associated with a 35.72 mL decrease in forced vital capacity (FVC) and a 24.89 mL decrease in forced expiratory volume in 1 s (FEV1) in the baseline analyses. In the follow-up analyses, there was a negative association between urinary zinc and FVC among participants with persistent high urinary zinc levels, with an estimated change of −93.31 mL (95% CI −178.47 to −8.14). Furthermore, urinary zinc was positively associated with restrictive ventilatory impairment. The mediation analyses suggested that C reactive protein mediated 8.62% and 8.71% of the associations of urinary zinc with FVC and FEV1, respectively.

Conclusion

Urinary zinc was negatively associated with lung function, and the systemic inflammation may be one of the underlying mechanisms.

Acrylamide Exposure and Oxidative DNA Damage, Lipid Peroxidation, and Fasting Plasma Glucose Alteration: Association and Mediation Analyses in Chinese Urban Adults

OBJECTIVE

Acrylamide exposure from daily-consumed food has raised global concern. We aimed to assess the exposure-response relationships of internal acrylamide exposure with oxidative DNA damage, lipid peroxidation, and fasting plasma glucose (FPG) alteration and investigate the mediating role of oxidative DNA damage and lipid peroxidation in the association of internal acrylamide exposure with FPG.

RESEARCH DESIGN AND METHODS

FPG and urinary biomarkers of oxidative DNA damage (8-hydroxy-deoxyguanosine [8-OHdG]), lipid peroxidation (8-iso-prostaglandin-F2α [8-iso-PGF2α]), and acrylamide exposure (N-acetyl-S-[2-carbamoylethyl]-l-cysteine [AAMA], N-acetyl-S-[2-carbamoyl-2-hydroxyethyl]-l-cysteine [GAMA]) were measured for 3,270 general adults from the Wuhan-Zhuhai cohort. The associations of urinary acrylamide metabolites with 8-OHdG, 8-iso-PGF2α, and FPG were assessed by linear mixed models. The mediating roles of 8-OHdG and 8-iso-PGF2α were evaluated by mediation analysis.

RESULTS

We found significant linear positive dose-response relationships of urinary acrylamide metabolites with 8-OHdG, 8-iso-PGF2α, and FPG (except GAMA with FPG) and 8-iso-PGF2α with FPG. Each 1-unit increase in log-transformed level of AAMA, AAMA + GAMA (ΣUAAM), or 8-iso-PGF2α was associated with a 0.17, 0.15, or 0.23 mmol/L increase in FPG, respectively (P and/or P trend < 0.05). Each 1% increase in AAMA, GAMA, or ΣUAAM was associated with a 0.19%, 0.27%, or 0.22% increase in 8-OHdG, respectively, and a 0.40%, 0.48%, or 0.44% increase in 8-iso-PGF2α, respectively (P and P trend < 0.05). Increased 8-iso-PGF2α rather than 8-OHdG significantly mediated 64.29% and 76.92% of the AAMA- and ΣUAAM-associated FPG increases, respectively.

CONCLUSIONS

Exposure of the general adult population to acrylamide was associated with FPG elevation, oxidative DNA damage, and lipid peroxidation, which in turn partly mediated acrylamide-associated FPG elevation.

Association between maternal antimony exposure and risk of gestational diabetes mellitus: A birth cohort study

BACKGROUND

A small number of epidemiological studies have suggested the association of antimony (Sb) exposure with type 2 diabetes risk. However, little is known about the relationship between Sb exposure during pregnancy and risk of gestational diabetes mellitus (GDM).

OBJECTIVES

To investigate the associations of urinary Sb concentrations with GDM risk and blood glucose levels in pregnant women.

METHODS

We analyzed the baseline data of 1789 pregnant women enrolled in the Birth Cohort Study on Prenatal Environments and Offspring Health (PEOH) in Guangzhou, China. Sb concentrations in urine were measured by inductively coupled plasma mass spectrometry (ICP-MS). Logistic regression and analysis of covariance were used to evaluate associations of Sb exposure with GDM risk and blood glucose levels.

RESULTS

A total of 437 (24.4%) women were diagnosed with GDM. The relative risk of GDM for women in the highest quartile of creatinine-corrected Sb (CC-Sb) concentrations was 1.55 [RR (95% CI) = 1.55 (1.12, 2.15), p-trend = 0.005], compared with women in the lowest quartile. Moreover, the women in the top quartile of CC-Sb levels had a 5.2% higher 1 h blood glucose and a 4.2% higher 2 h blood glucose than those in the bottom quartile. We also found an interactive effect between maternal age and CC-Sb on the risk of GDM (p-interaction < 0.001).

CONCLUSION

This study suggested significant positive associations of Sb exposure with increased GDM risk and impaired blood glucose homeostasis in pregnant women, and the Sb-GDM association might be modified by maternal age.

Exposure to multiple metals in early pregnancy and gestational diabetes mellitus: A prospective cohort study

BACKGROUND

A growing number of epidemiologic studies have estimated associations between type 2 diabetes mellitus and exposure to metals. However, studies on the associations of internal assessments of metal exposure and gestational diabetes mellitus (GDM) are limited in scope and have inconsistent outcomes.

OBJECTIVES

This investigation aimed to explore the associations between urinary nickel (Ni), arsenic (As), cadmium (Cd), antimony (Sb), cobalt (Co), or vanadium (V) in early pregnancy and the subsequent risk of GDM in Chinese pregnant women.

METHODS

The study population included 2090 women with singleton pregnancy from the Tongji Maternal and Child Health Cohort (TMCHC). Urine samples were collected before 20 gestational weeks, and an oral glucose tolerance test (OGTT) was conducted at 24-28 gestational weeks to diagnose GDM. The concentrations of urinary metals were measured using inductively coupled plasma mass spectrometry (ICP-MS) and were corrected for urinary creatinine. The associations between the risk of GDM and urinary metals were assessed using Poisson regression with a robust error variance with generalized estimating equations (GEE) models and Bayesian kernel machine regression (BKMR).

RESULTS

A total of 241 participants (11.53%) were diagnosed with GDM. Five metals (Ni, As, Sb, Co, and V) were found significantly and positively associated with GDM based on single-metal models. In multiple-metal models, for each unit increase of ln-transformed urinary Ni or Sb, the risk of GDM increased 18% [relative risk (RR):1.18, 95%confidence interval (CI): 1.00, 1.38 or RR: 1.18, 95%CI: 1.00, 1.39, respectively]. The BKMR analysis revealed a statistically significant and positive joint effect of the six metals on the risk of GDM, when the urinary levels of the six metals were all above the 55th percentile, compared to the median levels. The effect of metal Ni was significant when the concentrations of the other metals were all fixed at their 25th percentile, and metal Sb displayed a significant and positive effect when all the other metals were fixed at 25th, 50th, and 75th percentiles.

CONCLUSIONS

To the best of our knowledge, this study is the first to demonstrate that increased concentrations of urinary Ni in early pregnancy are associated with an elevated risk of GDM, either evaluated individually or as a metal mixture. All six metals mixed exposure was positively associated with the risk of GDM, while Sb and Ni were demonstrated more important effects than the other four metals in the mixture.

Oxidatively Damaged DNA/RNA and 8-Isoprostane Levels Are Associated With the Development of Type 2 Diabetes at Older Age: Results From a Large Cohort Study

OBJECTIVE

Oxidative stress is believed to play an important role in the pathophysiology of type 2 diabetes, but the few cohort studies that have assessed the association of oxidative stress biomarkers with type 2 diabetes incidence were small and reported inconclusive results.

RESEARCH DESIGN AND METHODS

We examined the associations of urinary oxidized guanine/guanosine (OxGua) levels (a biomarker of DNA/RNA oxidation) and urinary 8-isoprostane levels (a biomarker of lipid peroxidation) with type 2 diabetes incidence in 7,828 individuals initially without diabetes from a population-based German cohort study with 14 years of follow-up. Hazard ratios (HRs) (95% CIs) per 1 SD were obtained using multivariable-adjusted Cox proportional hazards regression models.

RESULTS

In the total population, weak but statistically significant associations with type 2 diabetes incidence were observed for OxGua levels (HR [95% CI] per 1 SD 1.05 [1.01; 1.09]) and 8-isoprostane levels (1.04 [1.00; 1.09]). Stratified analyses showed that associations of both biomarkers with type 2 diabetes incidence were absent in the youngest age-group (50-59 years) and strongest in the oldest age-group (65-75 years) of the cohort, with HR of OxGua levels 1.14 (1.05; 1.23) per 1 SD and of 8-isoprostane levels 1.22 (1.02; 1.45) per 1 SD.

CONCLUSIONS

These results from a large cohort study support suggestions that an imbalanced redox system contributes to the development of type 2 diabetes but suggest that this association becomes clinically apparent at older ages only, possibly as a result of reduced cellular repair capacity.