Multiple metal concentrations and gestational diabetes mellitus in Taiyuan, China

Association between mixed metal exposure and stroke risk in Shanxi Province: a case-control study

BACKGROUND

Stroke is the second leading cause of death for all human beings and poses a serious threat to human health. Environmental exposure to a mixture of metals may be associated with the occurrence and development of stroke, but the evidence in the Chinese population is not yet conclusive.

OBJECTIVES

This study evaluated the association between stroke risk and 13 metals METHODS: Metal concentrations in whole blood samples from 100 stroke cases and 100 controls were measured by ICP-MS. The cumulative impact of mixed metal on stroke risk was investigated by using three statistical models, BKMR, WQS and QGC.

RESULTS

The case group had higher concentrations of Mg, Mn, Zn, Se, Sn, and Pb than the control group (p<0.05). BKMR model indicated a correlation between the risk of stroke and exposure to mixed metals. WQS model showed that Mg (27.2 %), Se (25.1 %) and Sn (14.8 %) were positively correlated with stroke risk (OR=1.53; 95 %Cl: 1.03-2.37, p=0.013). The QGC model showed that Mg (49.2 %) was positively correlated with stroke risk, while Ti (31.7 %) was negatively correlated with stroke risk.

CONCLUSIONS

Mg may be the largest contributor to the cumulative effect of mixed metal exposure on stroke risk, and the interaction between metals requires more attention. These findings could provide scientific basis for effectively preventing stroke by managing metals in the environment.

Maternal exposure to bisphenols, phthalates, perfluoroalkyl acids, and trace elements and their associations with gestational diabetes mellitus in the APrON cohort

The increasing global prevalence of gestational diabetes mellitus (GDM) has been hypothesized to be associated with maternal exposure to environmental chemicals. Here, among 420 women participating in the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort study, we examined associations between GDM and second trimester blood or urine concentrations of endocrine disrupting chemicals (EDCs): bisphenol-A (BPA), bisphenol-S (BPS), twelve phthalate metabolites, eight perfluoroalkyl acids (PFAAs), and eleven trace elements. Fifteen (3.57%) of the women were diagnosed with GDM, and associations between the environmental chemical exposures and GDM diagnosis were examined using multiple logistic and LASSO regression analyses in single- and multi-chemical exposure models, respectively. In single chemical exposure models, BPA and mercury were associated with increased odds of GDM, while a significant inverse association was observed for zinc. Double-LASSO regression analysis selected mercury (AOR: 1.51, CI: 1.12-2.02), zinc (AOR: 0.017, CI: 0.0005-0.56), and perfluoroundecanoic acid (PFUnA), a PFAAs, (AOR: 0.43, CI: 0.19-0.94) as the best predictors of GDM. The combined data for this Canadian cohort suggest that second trimester blood mercury was a robust predictor of GDM diagnosis, whereas blood zinc and PFUnA were protective factors. Research into mechanisms that underlie the associations between mercury, zinc, PFUnA, and the development of GDM is needed.

Vitamin C Alleviates the Risk of Gestational Diabetes Mellitus Associated With Exposure to Metals

Background: Exposure to heavy metals has been suggested to increase the risk of gestational diabetes mellitus (GDM) through the oxidative stress pathway. The study is aimed at examining whether vitamin C could modify the association between exposure to heavy metals and risk of GDM. Methods: We conducted a case-control study in Taiyuan, China, with 776 GDM cases and 776 controls. Data on vitamin C intake from diet and supplements were collected through questionnaires. Concentrations of metals in participants' blood were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Unconditional logistic regression models were applied to estimate effect modification of vitamin C on the association between heavy metals and GDM. Results: Women with higher blood levels of mercury (Hg) (odds ratio (OR) = 2.36, 95% confidence interval (CI): 1.43, 3.92 and 2.04, 95% CI: 1.20, 3.46 for the second and third vs. the first tertile) and arsenic (As) (OR = 2.46, 95% CI: 1.37, 4.43 and 2.16, 95% CI: 1.12, 4.17 for the second and third vs. the first tertile) exposure were associated with increased risk of GDM among women without vitamin C supplement use and having dietary vitamin C intake < 85 mg/day. We found no significant association with metals among women who took vitamin C supplements and/or dietary vitamin C ≥ 85 mg/day. Significant interactions were observed between vitamin C and exposures to metals (i.e., Hg and As) on the risk of GDM (P interaction = 0.048 and 0.045, respectively). Conclusions: Our study, for the first time, suggests that vitamin C supplement use or higher dietary vitamin C intake during preconception and early pregnancy could alleviate the risk of GDM associated with exposure to As and Hg. The results warrant further investigation.

A prospective cohort study of multimetal exposure and risk of gestational diabetes mellitus

The relationship between co-exposure to multiple metals and gestational diabetes mellitus (GDM) and the mechanisms involved are poorly understood. In this nested case-control study, 228 GDM cases and 456 matched controls were recruited, and biological samples were collected at 12-14 gestational weeks. The urinary concentrations of 10 metals and 8-hydroxydeoxyguanosine (8-OHdG) as well as the serum levels of malondialdehyde (MDA) and advanced glycation end products (AGEs) were determined to assess the association of metals with GDM risk and the mediating effects of oxidative stress. Urinary Ti concentration was significantly and positively associated with the risk of GDM (odds ratio [OR]:1.45, 95 % confidence interval [CI]: 1.12, 1.88), while Mn and Fe were negatively associated with GDM risk (OR: 0.67, 95 % CI: 0.50, 0.91 or OR: 0.61, 95 % CI: 0.47, 0.80, respectively). A significant negative association was observed between Mo and GDM risk, specifically in overweight and obese pregnant women. Bayesian kernel machine regression showed a significant negative joint effect of the mixture of 10 metals on GDM risk. The adjusted restricted cubic spline showed a protective role of Mn and Fe in GDM risk (P < 0.05). A significant negative association was observed between essential metals and GDM risk in quantile g-computation analysis (P < 0.05). Mediation analyses showed a mediating effect of MDA on the association between Ti and GDM risk, with a proportion of 8.7 % (P < 0.05), and significant direct and total effects on Ti, Mn, and Fe. This study identified Ti as a potential risk factor and Mn, Fe, and Mo as potential protective factors against GDM, as well as the mediating effect of lipid oxidation.

Effects of exposure to multiple metallic elements in the first trimester of pregnancy on the risk of preterm birth

Exposure to certain heavy metals has been demonstrated to be associated with a higher risk of preterm birth (PTB). However, studies focused on the effects of other metal mixtures were limited. A nested case‒control study enrolling 94 PTB cases and 282 controls was conducted. Metallic elements were detected in maternal plasma collected in the first trimester using inductively coupled plasma‒mass spectrometry. The effect of maternal exposure on the risk of PTB was investigated using logistic regression, least absolute shrinkage and selection operator, restricted cubic spline (RCS), quantile g computation (QGC) and Bayesian kernel machine regression (BKMR). Vanadium (V) and arsenic (As) were positively associated with PTB risk in the logistic model, and V remains positively associated in the multi-exposure logistic model. QGC analysis determined V (69.42%) and nickel (Ni) (70.30%) as the maximum positive and negative contributors to the PTB risk, respectively. BKMR models further demonstrated a positive relationship between the exposure levels of the mixtures and PTB risk, and V was identified as the most important independent variable among the elements. RCS analysis showed an inverted U-shape effect of V and gestational age, and plasma V more than 2.18 μg/L was considered a risk factor for shortened gestation length. Exposure to metallic elements mixtures consisting of V, As, cobalt, Ni, chromium and manganese in the first trimester was associated with an increased risk of PTB, and V was considered the most important factor in the mixtures in promoting the incidence of PTB.

Metalloestrogens exposure and risk of gestational diabetes mellitus: Evidence emerging from the systematic review and meta-analysis

BACKGROUND

Metalloestrogens are metals and metalloid elements with estrogenic activity found everywhere. Their impact on human health is becoming more apparent as human activities increase.

OBJECTIVE

Our aim is to conduct a comprehensive systematic review and meta-analysis of observational studies exploring the correlation between metalloestrogens (specifically As, Sb, Cr, Cd, Cu, Se, Hg) and Gestational Diabetes Mellitus (GDM).

METHODS

PubMed, Web of Science, and Embase were searched to examine the link between metalloestrogens (As, Sb, Cr, Cd, Cu, Se, and Hg) and GDM until December 2023. Risk estimates were derived using random effects models. Subgroup analyses were conducted based on study countries, exposure sample, exposure assessment method, and detection methods. Sensitivity analyses and adjustments for publication bias were carried out to assess the strength of the findings.

RESULTS

Out of the 389 articles identified initially, 350 met our criteria and 33 were included in the meta-analysis, involving 141,175 subjects (9450 cases, 131,725 controls). Arsenic, antimony, and copper exposure exhibited a potential increase in GDM risk to some extent (As: OR = 1.28, 95 % CI [1.08, 1.52]; Sb: OR = 1.73, 95 % CI [1.13, 2.65]; Cu: OR = 1.29, 95 % CI [1.02, 1.63]), although there is a high degree of heterogeneity (As: Q = 52.93, p < 0.05, I2 = 64.1 %; Sb: Q = 31.40, p < 0.05, I2 = 80.9 %; Cu: Q = 21.14, p < 0.05, I2 = 71.6 %). Conversely, selenium, cadmium, chromium, and mercury exposure did not exhibit any association with the risk of GDM in our study.

DISCUSSION

Our research indicates that the existence of harmful metalloestrogens in the surroundings has a notable effect on the likelihood of GDM. Hence, we stress the significance of environmental elements in the development of GDM and the pressing need for relevant policies and measures.

Association of exposure to multiple heavy metals during pregnancy with the risk of gestational diabetes mellitus and insulin secretion phase after glucose stimulation

BACKGROUND

Epidemiological evidence for the association between heavy metals exposure during pregnancy and gestational diabetes mellitus (GDM) is still inconsistent. Additionally, that is poorly understood about the potential cause behind the association, for instance, whether heavy metal exposure is related to the change of insulin secretion phase is unknown.

OBJECTIVES

We aimed to explore the relationships of blood levels of arsenic (As), lead (Pb), thallium (Tl), nickel (Ni), cadmium (Cd), cobalt (Co), barium (Ba), chromium (Cr), mercury (Hg) and copper (Cu) during early pregnancy with the odds of GDM, either as an individual or a mixture, as well as the association of the metals with insulin secretion phase after glucose stimulation.

METHODS

We performed a nested case-control study consisting of 302 pregnant women with GDM and 302 controls at the First Affiliated Hospital of Anhui Medical University in Hefei, China. Around the 12th week of pregnancy, blood samples of pregnant women were collected and levels of As, Pb, Tl, Ni, Cd, Co, Ba, Cr, Hg and Cu in blood were measured. An oral glucose tolerance test (OGTT) was done in each pregnant woman during the 24-28th week of pregnancy to diagnose GDM and C-peptide (CP) levels during OGTT were measured simultaneously. The four metals (As, Pb, Tl and Ni) with the highest effect on odds of GDM were selected for the subsequent analyses via the random forest model. Conditional logistic regression models were performed to analyze the relationships of blood As, Pb, Tl and Ni levels with the odds of GDM. The weighted quantile sum (WQS) regression and bayesian kernel machine regression (BKMR) were used to assess the joint effects of levels of As, Pb, Tl and Ni on the odds of GDM as well as to evaluate which metal level contributed most to the association. Latent profile analysis (LPA) was conducted to identify profiles of glycemic and C-peptide levels at different time points. Multiple linear regression models were employed to explore the relationships of metals with glycaemia-related indices (fasting blood glucose (FBG), 1-hour blood glucose (1h BG), 2-hour blood glucose (2h BG), fasting C-peptide (FCP), 1-hour C-peptide (1h CP), 2-hour C-peptide (2h CP), FCP/FBG, 1h CP/1h BG, 2h CP/2h BG, area under the curve of C-peptide (AUCP), area under the curve of glucose (AUCG), AUCP/AUCG and profiles of BGs and CPs, respectively. Mixed-effects models with repeated measures data were used to explore the relationship between As (the ultimately selected metal) level and glucose-stimulated insulin secretion phase. The mediation effects of AUCP and AUCG on the association of As exposure with odds of GDM were investigated using mediation models.

RESULTS

The odds of GDM in pregnant women increased with every ln unit increase in blood As concentration (odds ratio (OR) = 1.46, 95% confidence interval (CI) = 1.04-2.05). The joint effects of As, Pb, Tl and Ni levels on the odds of GDM was statistically significant when blood levels of four metals were exceeded their 50th percentile, with As level being a major contributor. Blood As level was positively associated with AUCG and the category of glucose latent profile, the values of AUCG were much higher in GDM group than those in non-GDM group, which suggested that As exposure associated with the odds of GDM may be due to that As exposure was related to the impairment of glucose tolerance among pregnant women. The significant and positive relationships of As level with AUCP, CP latent profile category, 2h CP and 2h CP/2h BG were observed, respectively; and the values of 1h CP/1h BG and AUCP/AUCG were much lower in GDM group than those in non-GDM group, which suggested that As exposure may not relate to the impairment of insulin secretion (pancreatic β-cell function) among pregnant women. The relationships between As level and 2h CP as well as 2h CP/2h BG were positive and significant; additionally, the values of 2h CP/2h BG in GDM group were comparable with those in non-GDM group; the peak value of CP occurred at 2h in GDM group, as well as the values of 2h CP/2h BG in high As exposure group were much higher than those in low As exposure group, which suggested that As exposure associated with the increased odds of GDM may be due to that As exposure was related to the change of insulin secretion phase (delayment of the peak of insulin secretion) among pregnant women. In addition, AUCP mediated 11% (p < 0.05) and AUCG mediated 43% (p < 0.05) of the association between As exposure and the odds of GDM.

CONCLUSION

Our results suggested that joint exposure to As, Pb, Tl and Ni during early pregnancy was positively associated with the odds of GDM, As was a major contributor; and the association of environmental As exposure with the increased odds of GDM may be due to that As exposure was related to the impairment of glucose tolerance and change of insulin secretion phase after glucose stimulation (delayment of the peak of insulin secretion) among pregnant women.

Effect of arsenic on the risk of gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Gestational diabetes mellitus (GDM) is a complication of pregnancy associated with numerous adverse outcomes. There may be a potential link between GDM and arsenic (As) exposure, but this hypothesis remains controversial. This meta-analysis summarizes the latest studies evaluating the association between As and GDM.

METHODS

A comprehensive search of the PubMed, Embase, and Scopus databases up to September 2023 was performed. The pooled estimates with 95% CIs were presented using forest plots. Estimates were calculated with random effects models, and subgroup and sensitivity analyses were conducted to address heterogeneity.

RESULTS

A total of 13 eligible studies involving 2575 patients with GDM were included in this meta-analysis. The results showed that women exposed to As had a significantly increased risk of GDM (OR 1.47, 95% CI: 1.11 to 1.95, P = 0.007). Subgroup analyses suggested that the heterogeneity might be attributed to the years of publication. In addition, sensitivity analysis confirmed the robust and reliable results.

CONCLUSIONS

This analysis suggested that women exposed to As have a greater risk of GDM. However, the significant heterogeneity across studies requires careful interpretation.

REGISTRATION

The PROSPERO registration ID is CRD42023461820.

Cadmium Exposure was Associated with Sex-Specific Thyroid Dysfunction: Consistent Evidence from Two Independent Cross-Sectional Studies Based on Urinary and Blood Cadmium Measurements

Population-based studies on the association between cadmium (Cd) exposure and thyroid function are limited and have shown conflicting results. Two independent cross-sectional studies using different Cd biomarkers were carried out in six rural areas with different soil Cd levels in China. Thyroid dysfunction was defined based on levels of thyroid stimulating hormone (TSH) and free thyroxine (FT4). Multivariable linear regression, multiple logistic regression, and restrictive cubic splines models were used to estimate the association between Cd and thyroid dysfunction. For both of the two independent studies, higher Cd levels were observed to be associated with lower TSH levels and higher risk of thyroid dysfunction. The negative relationship between urinary Cd and TSH was found in both total participants (β =  - 0.072, p = 0.008) and males (β =  - 0.119, p = 0.020) but not in females; however, the negative relationship between blood Cd and TSH was only found in females (β =  - 0.104, p = 0.024). Higher urinary Cd was associated with higher risk of thyroid dysfunction (OR = 1.77, p = 0.031), while higher blood Cd was associated with higher risk of thyroid dysfunction (OR = 1.95, p = 0.011). Results from the two independent cross-sectional studies consistently suggested that higher Cd levels were associated with sex-specific thyroid dysfunction.

Update of the risk assessment of inorganic arsenic in food

The European Commission asked EFSA to update its 2009 risk assessment on arsenic in food carrying out a hazard assessment of inorganic arsenic (iAs) and using the revised exposure assessment issued by EFSA in 2021. Epidemiological studies show that the chronic intake of iAs via diet and/or drinking water is associated with increased risk of several adverse outcomes including cancers of the skin, bladder and lung. The CONTAM Panel used the benchmark dose lower confidence limit based on a benchmark response (BMR) of 5% (relative increase of the background incidence after adjustment for confounders, BMDL05) of 0.06 μg iAs/kg bw per day obtained from a study on skin cancer as a Reference Point (RP). Inorganic As is a genotoxic carcinogen with additional epigenetic effects and the CONTAM Panel applied a margin of exposure (MOE) approach for the risk characterisation. In adults, the MOEs are low (range between 2 and 0.4 for mean consumers and between 0.9 and 0.2 at the 95th percentile exposure, respectively) and as such raise a health concern despite the uncertainties.

Combined exposure to multiple essential elements and cadmium at early pregnancy on gestational diabetes mellitus: a prospective cohort study

Background

Minerals and trace elements were involved in the pathogenesis and progression of diabetes. However, the association of mixed exposure to essential elements and toxic elements with gestational diabetes mellitus (GDM) is poorly understood.

Objective

This study aims to examine the associations between serum calcium (Ca), iron (Fe), zinc (Zn), copper (Cu), magnesium (Mg), and cadmium (Cd) concentrations in early pregnancy and GDM risk in Chinese pregnant women.

Method

A total of 1,168 pregnant women were included in this prospective cohort study. The concentrations of serum elements were measured using the polarography method before 14 gestational weeks and an oral glucose tolerance test was conducted at 24-28 gestational weeks to diagnose GDM. Binary logistic regression analysis and restricted cubic spline were applied to evaluate the association between serum individual element and GDM. Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression were used to assess the associations between mixed essential elements and Cd exposure and GDM risk.

Results

The mean concentrations of Zn (124.65 vs. 120.12 μmol/L), Fe (135.26 vs. 132.21 μmol/L) and Cu (23.33 vs. 23.03 μmol/L) in the GDM group were significantly higher than those in the control group. Single-element modeling results suggested that second and fourth-quartile maternal Zn and Fe concentration, third and fourth-quartile Cu concentration and fourth-quartile Ca concentration were associated with an increased risk of GDM compared to first-quartile values. Restricted cubic spline analysis showed U-shaped and non-linear relationships between Cd and GDM. According to the BKMR models and WQS analyses, a six-element mixture was significantly and positively associated with the risk of GDM. Additionally, Cd, Zn, and Cu contributed the most strongly to the association.

Conclusion

Serum Zn, Cu, Fe, and Ca exposure during early pregnancy showed a positive association with GDM in the individual evaluation. The multiple-evaluation showed that high levels of elements mixture, particularly Cd, Zn, and Cu, may promote the development of GDM.

Higher cadmium exposure was associated with sex-specific thyroid dysfunction: Consistent evidence from two independent cross-sectional studies based on urinary and blood cadmium measurements

Population-based studies on the association between cadmium (Cd) exposure and thyroid function are limited and have shown conflicting results. Two independent cross-sectional studies using different Cd biomarkers were carried out in six rural areas with different soil Cd levels in China. Thyroid dysfunction was defined based on levels of thyroid stimulating hormone (TSH) and free thyroxine (FT4). Both multivariable linear regression, multiple logistic regression and restrictive cubic splines models were used to estimate the association between Cd and thyroid dysfunction. For both of the two independent studies, higher Cd levels were observed to be associated with lower TSH levels and higher risk of thyroid dysfunction. The negative relationship between urinary Cd and TSH was found in both total participants (β = -0.072, p = 0.008) and males (β = -0.119, p = 0.020) but not in females, however, the negative relationship between blood Cd and TSH was only found in females (β = -0.104, p = 0.024). Higher urinary Cd (> 2.52 μg/g creatinine) was associated with higher risk of thyroid dysfunction, while higher blood Cd was associated with higher risk of hyperthyroidism status. The adjusted Odds Ratio (OR) for the risk of hyperthyroidism status was 3.48 (95%CI:1.36-8.92) and 6.94 (95%CI:1.23-39.31) times higher with every natural log unit higher in blood Cd in total participants and males, respectively. Results from the two independent cross-sectional studies consistently suggested that higher Cd levels were associated with sex-specific thyroid dysfunction.

Metal Exposure during Early Pregnancy and Risk of Gestational Diabetes Mellitus: Mixture Effect and Mediation by Phospholipid Fatty Acids

Despite existing studies exploring the association between metal exposure and gestational diabetes mellitus (GDM), most of them have focused on a single metal or a small mixture of metals. Our prospective work investigated the joint and independent effects of early gestational exposure to 17 essential and nonessential metals on the GDM risk and potential mediation by plasma phospholipid fatty acids (PLFAs) based on a nested case-control study established with 335 GDM cases and 670 randomly matched healthy controls. The Bayesian kernel machine regression (BKMR) and quantile g-computation analyses demonstrated a joint effect from metal co-exposure on GDM risk. BKMR with hierarchical variable selection indicated that the group of essential metals was more strongly associated with GDM than the group of nonessential metals with group posterior inclusion probabilities (PIPs) of 0.979 and 0.672, respectively. Cu (0.988) and Ga (0.570) had the largest conditional PIPs within each group. We also observed significant mediation effects of selected unsaturated PLFAs on Cu-GDM and Ga-GDM associations. KEGG enrichment analysis further revealed significant enrichment in the biosynthesis of unsaturated PLFAs. C18:1 n-7 exhibited the largest proportion of mediation in both associations (23.8 and 22.9%). Collectively, our work demonstrated the joint effect of early gestational metal exposure on GDM risk and identified Cu and Ga as the key species to the joint effect. The findings lay a solid ground for further validation through multicenter investigations and mechanism exploration via laboratory studies.

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.

The associations of non-essential metal mixture with fasting plasma glucose among Chinese older adults without diabetes

The evidence about the effect of non-essential metal mixture on fasting plasma glucose (FPG) levels among older adults without diabetes is limited. This study aims to estimate the individual and joint relationship between five non-essential metals and FPG levels in Chinese older adults without diabetes. This study included 2362 older adults without diabetes. Urinary concentrations of five non-essential metals, i.e., cesium (Cs), aluminum (Al), thallium (Tl), cadmium (Cd), and arsenic (As), were detected by inductively coupled plasma mass spectrometry (ICP-MS). The associations of single metals and the metal mixture with FPG levels were assessed using linear regression and Bayesian kernel machine regression (BKMR) models, respectively. Adjusted single-metal linear regression models showed positive associations of urinary Al (β = 0.016, 95%CI: 0.001-0.030) and Cs (β = 0.018, 95%CI: 0.006-0.031) with FPG levels. When comparing the 2th, 3th, and 4th quartiles of urine Cs to its 1th quartile, the significant associations between Cs and FPG levels were found and presented as an "inverted U" trend (βQ2 vs. Q1: 0.034; βQ3 vs. Q1:0.054; βQ4 vs. Q1: 0.040; all P<0.05). BKMR analyses showed urinary level of Cs exhibited an "inverted U" shape association with FPG levels. Moreover, the FPG levels increased linearly with the raised levels of the non-essential metal mixture, and the posterior inclusion probability (PIP) of Cs was the highest (0.92). Potential positive interaction of As and Cs on FPG levels was found in BKMR model. Stratified analysis displayed significant interactions of hyperlipidemia and urine Cs or Tl on FPG levels. An inverse U-shaped association between Cs and FPG was found, individually and as mixture. The FPG levels increased with the raised levels of the non-essential metal mixture, and Cs was the most contributor to FPG levels. Further research is required to confirm the correlation between non-essential metals and FPG levels and to clarify the underlying mechanisms.

DNA methylation analysis reveals the effect of arsenic on gestational diabetes mellitus

BACKGROUND

Arsenic (As) exposure is one of the risk factors for gestational diabetes mellitus (GDM). This study aimed to explore the effect of As-exposure on DNA methylation in GDM and to establish a risk assessment model of GDM in As exposed pregnant women.

METHOD

We collected elbow vein blood of pregnant women before delivery to measure As concentration and DNA methylation data. Then compared the DNA methylation data and established a nomogram.

RESULT

We identified a total of 10 key differentially methylated CpGs (DMCs) and found 6 corresponding genes. Functions were enriched in Hippo signaling pathway, cell tight junction, prophetic acid metabolism, ketone body metabolic process, and antigen processing and presentation. A nomogram was established that can predict GDM risks (c-index = 0.595, s:p = 0.973).

CONCLUSION

We found 6 genes associated with GDM with high As exposure. The prediction of the nomograms has been proven to be effective.

Mass spectrometry-based "omics" technologies for the study of gestational diabetes and the discovery of new biomarkers

Gestational diabetes (GDM) is one of the most common complications occurring during pregnancy. Diagnosis is performed by oral glucose tolerance test, but harmonized testing methods and thresholds are still lacking worldwide. Short-term and long-term effects include obesity, type 2 diabetes, and increased risk of cardiovascular disease. The identification and validation of sensitidve, selective, and robust biomarkers for early diagnosis during the first trimester of pregnancy are required, as well as for the prediction of possible adverse outcomes after birth. Mass spectrometry (MS)-based omics technologies are nowadays the method of choice to characterize various pathologies at a molecular level. Proteomics and metabolomics of GDM were widely investigated in the last 10 years, and various proteins and metabolites were proposed as possible biomarkers. Metallomics of GDM was also reported, but studies are limited in number. The present review focuses on the description of the different analytical methods and MS-based instrumental platforms applied to GDM-related omics studies. Preparation procedures for various biological specimens are described and results are briefly summarized. Generally, only preliminary findings are reported by current studies and further efforts are required to determine definitive GDM biomarkers.

A machine learning approach for early prediction of gestational diabetes mellitus using elemental contents in fingernails

The aim of this pilot study was to predict the risk of gestational diabetes mellitus (GDM) by the elemental content in fingernails and urine with machine learning analysis. Sixty seven pregnant women (34 control and 33 GDM patient) were included. Fingernails and urine were collected in the first and second trimesters, respectively. The concentrations of elements were determined by inductively coupled plasma-mass spectrometry. Logistic regression model was applied to estimate the adjusted odd ratios and 95% confidence intervals. The predictive performances of multiple machine learning algorithms were evaluated, and an ensemble model was built to predict the risk for GDM based on the elemental contents in the fingernails. Beryllium, selenium, tin and copper were positively associated with the risk of GDM while nickel and mercury showed opposite result. The trained ensemble model showed larger area under curve (AUC) of receiver operating characteristic curve (0.81) using fingernail Ni, Cu and Se concentrations. The model was validated by external data set with AUC = 0.71. In summary, the results of the present study highlight the potential of fingernails, as an alternative sample, together with machine learning in human biomonitoring studies.

Temporal changes of blood mercury concentrations in Chinese newborns and the general public from 1980s to 2020s

Mercury (Hg) is a global pollutant that threatens the environment and human health. As a major producer, emitter and consumer of Hg, China is currently taking different measures to curb mercury pollution in accordance with the requirements of the Minamata Convention on Mercury. Blood Hg can reflect the human body's recent exposure to Hg. This review summarized the temporal changes in blood Hg concentrations in newborns and the general public in China from 1980 s to 2020 s. It was shown that the blood Hg concentrations of newborns showed the downward trend, although it was not significant. The general public Hg concentrations showed a trend of first increase and then decrease trend. Most of the cord blood Hg and venous blood Hg concentrations in China were lower than the USEPA reference concentration of 5.8 µg/L. Since low-dose prenatal Hg exposure can affect fetal and neonatal development, continuous attention needs to be paid to reduce maternal and neonatal Hg exposure. The information provided in this review may lay a basis for the effectiveness evaluation on the implementation of Minamata Convention on Mercury.

Consequences of the exposome to gestational diabetes mellitus

The exposome is the cumulative measure of environmental influences and associated biological responses throughout the lifespan, including those from the environment, diet, behaviour, and endogenous processes. The exposome concept and the 2030 Agenda for the Sustainable Development Goals (SDGs) from the United Nations are the basis for understanding the aetiology and consequences of non-communicable diseases, including gestational diabetes mellitus (GDM). Pregnancy may be developed in an environment with adverse factors part of the immediate internal medium for fetus development and the external medium to which the pregnant woman is exposed. The placenta is the interface between maternal and fetal compartments and acts as a protective barrier or easing agent to transfer exposome from mother to fetus. Under and over-nutrition in utero, exposure to adverse environmental pollutants such as heavy metals, endocrine-disrupting chemicals, pesticides, drugs, pharmaceuticals, lifestyle, air pollutants, and tobacco smoke plays a determinant role in the development of GDM. This phenomenon is worsened by metabolic stress postnatally, such as obesity which increases the risk of GDM and other diseases. Clinical risk factors for GDM development include its aetiology. It is proposed that knowledge-based interventions to change the potential interdependent ecto-exposome and endo-exposome could avoid the occurrence and consequences of GDM.

Arsenic and Diabetes Mellitus: A Putative Role for the Immune System

Diabetes mellitus (DM) is an enormous public health issue worldwide. Recent data suggest that chronic arsenic exposure is linked to the risk of developing type 1 and type 2 DM, albeit the underlying mechanisms are unclear. This review discusses the role of the immune system as a link to possibly explain some of the mechanisms of developing T1DM or T2DM associated with arsenic exposure in humans, animal models, and in vitro studies. The rationale for the hypothesis includes: (1) Arsenic is a well-recognized modulator of the immune system; (2) arsenic exposures are associated with increased risk of DM; and (3) dysregulation of the immune system is one of the hallmarks in the pathogenesis of both T1DM and T2DM. A better understanding of DM in association with immune dysregulation and arsenic exposures may help to understand how environmental exposures modulate the immune system and how these effects may impact the manifestation of disease.

Higher blood selenium level is associated with lower risk of hyperhomocysteinemia in the elderly

BACKGROUND AND AIMS

Earlier studies have reported inconsistent association between selenium (Se) and homocysteine (Hcy) levels, while no evidence could be found from Chinese population. To fill this gap, we investigated the association between blood Se and hyperhomocysteinemia (HHcy) of rural elderly population in China.

METHODS

A cross-sectional study on 1823 participants aged 65 and older from four Chinese rural counties was carried out in this study. Whole blood Se and serum Hcy concentrations were measured in fasting blood samples. Analysis of covariance and restricted cubic spline models were used to examine the association between Se and Hcy levels. Logistic regression models were used to evaluate the risk of prevalent HHcy among four Se quartile groups after adjusting for covariates.

RESULTS

For this sample, the mean blood Se concentration was 156.34 (74.65) μg/L and the mean serum Hcy concentration was 17.25 (8.42) μmol/L. A significant non-linear relationship was found between blood Se and serum Hcy, the association was inverse when blood Se was less than 97.404 μg/L and greater than 156.919 μg/L. Participants in the top three blood Se quartile groups had significantly lower risk of prevalent HHcy compared with the lowest quartile group. When defined as Hcy> 10 μmol/L, the odds ratios and 95% confidence interval of HHcy were 0.600 (0.390, 0.924), 0.616 (0.398, 0.951) and 0.479 (0.314, 0.732) for Q2, Q3, and Q4 Se quartile groups compared with the Q1 group, respectively. When defined as Hcy≥ 15 μmol/L, the odds ratios and 95% confidence interval of HHcy were 0.833 (0.633, 1.098) and 0.827 (0.626, 1.092), 0.647 (0.489, 0.857) for Q2, Q3, and Q4 Se quartile groups compared with Q1 group.

CONCLUSIONS

Our findings suggest that higher blood Se level could be a protective factor for HHcy in the elderly.

Association between Plasma Trace Element Concentrations in Early Pregnancy and Gestational Diabetes Mellitus in Shanghai, China

(1) Background: Trace elements play important roles in gestational diabetes mellitus (GDM), but the results from reported studies are inconsistent. This study aimed to examine the association between maternal exposure to V, Cr, Mn, Co, Ni, and Se in early pregnancy and GDM. (2) Methods: A nested case-control study with 403 GDM patients and 763 controls was conducted. Trace elements were measured using inductively coupled plasma-mass spectrometry in plasma collected from pregnant women in the first trimester of gestation. We used several statistical methods to explore the association between element exposure and GDM risk. (3) Results: Plasma V and Ni were associated with increased and decreased risk of GDM, respectively, in the single-element model. V and Mn were found to be positively, and Ni was found to be negatively associated with GDM risk in the multi-element model. Mn may be the main contributor to GDM risk and Ni the main protective factor against GDM risk in the quantile g computation (QGC). 6.89 μg/L~30.88 μg/L plasma Ni was identified as a safe window for decreased risk of GDM. (4) Conclusions: V was positively associated with GDM risk, while Ni was negatively associated. Ni has dual effects on GDM risk.

Plasma Manganese Levels and Risk of Gestational Diabetes Mellitus: A Prospective Cohort Study

Manganese (Mn) intake has been found to be linked with risk of type 2 diabetes. However, the role of Mn in the development of gestational diabetes mellitus (GDM) remains to be investigated. This prospective study included pregnant women from the Tongji Maternal and Child Health Cohort. A total of 2327 participants with plasma specimens before 20 weeks were included. Among the pregnant women, 9.7% (225/2327) were diagnosed with GDM. After adjustment, pregnant women with the third and highest quartile of plasma Mn levels had 1.31-fold (RR, 2.31 [1.48, 3.61]) and 2.35-fold (RR, 3.35 [2.17, 5.17]) increased risk of GDM compared with those with the lowest quartile. A 1 standard deviation increment of ln-transformed plasma Mn levels (0.53 μg/L) was related to elevated risks of GDM with RRs of 1.28 [1.17, 1.40]. The positive associations between Mn and GDM remained consistent in all the subgroups. The weighted quantile sum index was significantly related to GDM (RR, 1.60 [1.37, 1.86]). The contribution of Mn (58.69%) to the metal mixture index was the highest related to GDM. Higher plasma Mn levels were found to be linked with elevated fasting and 2 h post-load blood glucose. This study revealed relationships of higher plasma Mn levels in early pregnancy and increased risk of GDM, suggesting that though essential, excess Mn in the body might be a potential important risk factor for GDM.

Cadmium exposure and the risk of GDM: evidence emerging from the systematic review and meta-analysis

Gestational diabetes mellitus (GDM) has become a global concern for its severe adverse effects on both mother and fetus. Recent epidemiological studies reported inconsistent results of the association between cadmium (Cd) exposure and GDM. Therefore, a systematic review and meta- analysis were performed. PubMed, Web of Science, Scopus, Embase, and SpringerLink were searched up to July 2021. Observational studies containing the adjusted relative risks between Cd exposure and GDM were included in the quantitative synthesis. The retrieval comprised 218 articles out of which 11 met our criteria and 9 were included in the meta-analysis, representing a total of 32,392 subjects (2881 GDM). In total, Cd exposure might increase the risk of GDM in some extent (OR = 1.21, 95% CI [0.89, 1.64]), even without statistical significance in high heterogeneity (Q = 28.45, p < 0.05, I² = 71.9%). Filtering two outliers indicated by Galbraith plot yielded a similar risk (OR = 1.19, 95% CI [1.02, 1.39]) with statistical significance. However, the heterogeneity among studies was obviously reduced (Q = 11.75, p = 0.068, I² = 48.9%). Additionally, biological specimen, study design, and diagnostic criteria contributed to the high heterogeneity according to the subgroup analysis. Since some important results do not deny that Cd exposure increases the risk of GDM, high-quality multi-centered large cohort studies are required in the future.

Higher selenium was associated with higher risk of diabetes: Consistent evidence from longitudinal and cross-sectional studies based on nail and serum selenium measures

Although the association between selenium (Se) and diabetes has been well-discussed in recent years, few studies have focused on the effects of long-term natural Se exposure and rarely concerned the effects of different Se biomarkers. To address this question, we carried out a 7-year longitudinal study on older adults aged over 65 and another cross-sectional study on middle-aged and older adults aged 40 and above from Chinese soil Se-deplete and Se-optimum areas. Cox proportional hazard models were used to evaluate the associations between nail Se levels and incidence risk of diabetes. Unconditional logistic regression models and analysis of variance models were used to examine the associations between serum Se levels and the prevalence risk of diabetes. The nail and serum Se levels were 0.47 ± 0.20 μg/g and 111.09 ± 55.01 μg/L for the two study populations, respectively. For both of the independent studies, higher Se levels were observed to be associated with a higher risk of diabetes and prediabetes. Compared with the Second nail Se quartile (Q2), the adjusted hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) of diabetes for Q1, Q3 and Q4 were 1.24(0.70, 2.21), 1.53(0.98, 2.39) and 1.31(0.76, 2.26), respectively, and the adjusted HRs (95 % CIs) of prediabetes were 1.47(0.77, 2.81), 1.38(0.83, 2.30), and 1.97(1.13, 3.44), respectively. Compared with the first serum Se quintile (Q1), the adjusted odds ratios (ORs) and 95 % CIs of diabetes for higher quintiles were 1.12(0.75, 1.66), 1.05(0.71, 1.57), 1.09(0.73, 1.62) and 1.51(1.02, 2.19), and the adjusted ORs (95 % CIs) of prediabetes were 1.27(0.77, 2.09), 1.70(1.05, 2.74), 1.94(1.21, 3.11) and 1.67(1.03, 2.71). Our findings consistently suggest that higher Se status is associated with a higher risk of diabetes in adults.

Association between whole blood metallic elements concentrations and gestational diabetes mellitus in Japanese women: The Japan environment and Children's study

BACKGROUND

Exposure to several metallic elements has been suggested as a risk factor for gestational diabetes mellitus (GDM), but inconsistent findings have been reported. This study aimed to examine the association between the maternal whole blood concentration of metallic elements (Hg, Pb, Cd, Mn, and Se) and GDM using the dataset of the Japan Environment and Children's Study (JECS), a nationwide birth cohort study, which was designed to examine the adverse effects of pre/post-natal exposure to hazardous environment.

METHODS

The data of 78,964 pregnant women who were participants of JECS were used. Blood samples were collected from the pregnant women at second/third trimester of gestation. We employed logistic regression analysis, quantile g-computation (QGC) and a distributed lag nonlinear model (DLNM) to examine the association between the blood concentration of metallic elements and the risk of GDM.

RESULTS

The prevalence of GDM was 2.1%. In the logistic regression analyses, maternal blood Hg was associated with an increased risk of GDM. In QGC analysis, although metallic elements mixtures were not related to an increased risk of GDM, Hg (52.6%) may be the main contributor. According to the results of DLNM, for maternal exposure to Hg, 4.99 ng/g was identified as its susceptible minimum window for elevated risk of GDM.

CONCLUSIONS

Our findings highlighted an association between Hg exposure and an increased risk of GDM. Studies of the underlying mechanisms and potential contributing factors, including fish intake, of this association are warranted.

Environmental health influences in pregnancy and risk of gestational diabetes mellitus: a systematic review

Background

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications globally. Environmental risk factors may lead to increased glucose levels and GDM, which in turn may affect not only the health of the mother but assuming hypotheses of "fetal programming", also the health of the offspring. In addition to traditional GDM risk factors, the evidence is growing that environmental influences might affect the development of GDM. We conducted a systematic review analyzing the association between several environmental health risk factors in pregnancy, including climate factors, chemicals and metals, and GDM.

Methods

We performed a systematic literature search in Medline (PubMed), EMBASE, CINAHL, Cochrane Library and Web of Science Core Collection databases for research articles published until March 2021. Epidemiological human and animal model studies that examined GDM as an outcome and / or glycemic outcomes and at least one environmental risk factor for GDM were included.

Results

Of n = 91 studies, we classified n = 28 air pollution, n = 18 persistent organic pollutants (POP), n = 11 arsenic, n = 9 phthalate n = 8 bisphenol A (BPA), n = 8 seasonality, n = 6 cadmium and n = 5 ambient temperature studies. In total, we identified two animal model studies. Whilst we found clear evidence for an association between GDM and air pollution, ambient temperature, season, cadmium, arsenic, POPs and phthalates, the findings regarding phenols were rather inconsistent. There were clear associations between adverse glycemic outcomes and air pollution, ambient temperature, season, POPs, phenols, and phthalates. Findings regarding cadmium and arsenic were heterogeneous (n = 2 publications in each case).

Conclusions

Environmental risk factors are important to consider in the management and prevention of GDM. In view of mechanisms of fetal programming, the environmental risk factors investigated may impair the health of mother and offspring in the short and long term. Further research is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13965-5.

Urinary element profiles and associations with cardiometabolic diseases: A cross-sectional study across ten areas in China

BACKGROUND

Existing evidence on the associations of urinary element profiles with related food intake and cardiometabolic diseases has been limited in China.

OBJECTIVES

To examine the associations of urinary toxic metals and other elements with food intakes and with the prevalence of cardiometabolic diseases.

METHODS

Inductively coupled plasma mass spectrometry was used to measure the concentrations of cadmium (Cd), arsenic (As), nickel (Ni), aluminum (Al), copper (Cu), and 16 other elements in spot urine samples collected from 19,380 adults in 10 geographically diverse areas of China during 2013-2014. The levels of creatinine-corrected elements were used to analyze their correlations with self-reported dietary intake and associations with prevalent diabetes (n = 1862), stroke (n = 1322) and ischemic heart disease (IHD) (n = 1690).

RESULTS

Overall, the mean (SD) age was 59.2 (10.1) years with a mean BMI of 24.2 (3.5) kg/m². Of the 21 elements, the median (IQR) concentrations varied from 0.49 (0.31-0.82) μg/g creatinine for vanadium (V) to 1666 (1189-2321) mg/g creatinine for potassium (K). Nine urinary elements [Cd, As, Ni, lead (Pb), boron (B), magnesium (Mg), rubidium (Rb), strontium (Sr), and cesium (Cs); all rs > 0.20, p < 0.001] were positively correlated with staple food intake, five [Cd, As, selenium (Se), Rb, and Cs; all rs > 0.20, p < 0.001] with animal-sourced food group, and one (Cd; r = 0.21, p < 0.05) with pickled vegetable intake. For diabetes, adjusted prevalence ratios (PRs) per SD of specific element levels were 1.10 [95% confidence interval (CI): 1.03-1.18] for Cd, 1.24 (1.18-1.31) for As, 1.33 (1.27-1.39) for Ni, 1.14 (1.09-1.20) for Al, and 1.24 (1.18-1.30) for Cu. Cd was positively associated with stroke (PR per SD = 1.13, 1.04-1.23), while none of the elements were significantly associated with IHD.

CONCLUSION

In China, the urinary levels of several toxic metals were significantly associated with the consumption of specific food groups and the risk of cardiometabolic diseases including diabetes and stroke.

The Association Between Cadmium Exposure and Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

Objective

Several studies have evaluated the association of cadmium exposure with the risk of gestational diabetes mellitus (GDM). However, the findings among these studies have been inconsistent. To further investigate the relationship, we carried out a meta-analysis to clarify the relationship between cadmium exposure and GDM risk.

Methods

Five databases (Scopus, PubMed, Web of Science, Cochrane, and CNKI) were searched for eligible studies until September 09, 2021. The quality of eligible studies was evaluated using the Newcastle–Ottawa quality assessment scale (NOS). The summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by random-effects models due to high heterogeneity. Sensitivity analysis was performed to explore the robustness of the results. Publication bias was evaluated by Egger's test and Begg's test. We also conducted meta-regression analysis and subgroup analysis to assess the potential sources of heterogeneity.

Results

A total of 10 studies with 32,000 participants related to our issue were included. Comparing the highest vs. lowest categories of cadmium exposure, no significant association was observed between cadmium exposure and the risk of GDM (OR = 1.16, 95% CI = 0.92–1.46, and P = 0.206). No publication bias was found in Begg's and Egger's tests (all P > 0.05). Meta-regression suggested that publication year was the potentially heterogeneous source (P = 0.034). Subgroup analysis of publication year showed that the OR of studies before the year of 2016 was 4.05 (95% CI = 1.87–8.76, P < 0.001), and prospective cohort studies showed a borderline increased GDM risk (OR = 1.15, 95% CI = 0.99–1.33, and P = 0.061).

Conclusion

Our results indicated no significant association between cadmium exposure and GDM risk. Further high-quality prospective studies, especially those using standard analytic methods for cadmium exposure, are warranted to confirm the results.

Arsenic exposure during pregnancy and postpartum maternal glucose tolerance: evidence from Bangladesh

BACKGROUND

Arsenic exposure has been associated with gestational diabetes mellitus. However, the extent to which arsenic exposure during pregnancy is associated with postpartum glucose intolerance is unknown.

METHODS

We studied 323 women in Bangladesh. We assessed arsenic exposure in early pregnancy via toenail and water samples. We measured fasting glucose and insulin in serum at a mean (SD) of 4.0 (3.5) weeks post-delivery. We ran covariate-adjusted, linear regression models to examine associations of arsenic concentrations with HOMA-IR, a marker of insulin resistance, and HOMA-β, a marker of beta cell function.

RESULTS

Median (IQR) arsenic concentration was 0.45 (0.67) μg/g in toenails and 2.0 (6.5) μg/L in drinking water. Arsenic concentrations during pregnancy were not associated with insulin resistance or beta cell function postpartum. HOMA-IR was 0.07% (- 3.13, 3.37) higher and HOMA-β was 0.96% (- 3.83, 1.99) lower per IQR increment in toenail arsenic, but effect estimates were small and confidence intervals crossed the null.

CONCLUSIONS

Although arsenic exposure during pregnancy has been consistently associated with gestational diabetes mellitus, we found no clear evidence for an adverse effect on postpartum insulin resistance or beta cell function.

Associations between multiple heavy metals exposure and glycated hemoglobin in a Chinese population

BACKGROUND

Heavy metals may play an important role as environmental risk factors in diabetes mellitus. This study aimed to explore the association of HbA1c with As, Cd, Cu, Ni, Pb, and Zn in single-metal exposure and multi-metal co-exposure models.

METHODS

A cross-sectional study involving 3472 participants was conducted. Plasma concentrations of heavy metals were determined by inductively coupled plasma mass spectrometry. We estimated the association of each metal with HbA1c by linear regression. Potential heterogeneities by sex, age, and smoking were investigated, and metal mixtures and interactions were assessed by the Bayesian kernel machine regression (BKMR).

RESULTS

In linear regression, Cu (β = 0.324, p < 0.05) and Ni (β = -0.19, p < 0.05) showed significant association with HbA1c in all participants. In BKMR analyses, all exposure-response relationships were approximately linear. Cu was significantly and positively associated with HbA1c levels in overall participants, women, participants aged 60 years old and above, and nonsmokers. Ni was significantly and negatively associated with HbA1c levels in overall participants. We did not observe the overall effect of plasma metal mixtures on HbA1c or the interaction effect of the metals on HbA1c.

CONCLUSION

Cu was positively correlated with HbA1c, whereas Ni was negatively correlated with HbA1c, when evaluated individually or in a metal mixture. Additional studies are necessary to confirm these correlations and to control for exposure to different metals in the general population.

Joint effect of urinary arsenic species and serum one-carbon metabolism nutrients on gestational diabetes mellitus: A cross-sectional study of Chinese pregnant women

BACKGROUND

Growing evidence indicates that arsenic (As) exposure can increase the risk of gestational diabetes mellitus (GDM). However, little is known about As species and GDM and the combined effect of As and one-carbon metabolism (OCM) on GDM.

OBJECTIVES

We aimed to examine the associations between As species and GDM and evaluate the potential interactions of folate, vitamin B₁₂, and homocysteine (Hcy) with As species on GDM prevalence.

METHOD

We measured levels of arsenite (As³⁺), arsenate (As⁵⁺), dimethylarsinic acid (DMA), and arsenobetaine (AsB) species in urine and folate, vitamin B₁₂, and Hcy in serum from 396 pregnant women in Tianjin, China. The diagnosis of GDM was based on an oral glucose tolerance test. Associations of As species in urine with GDM were evaluated using generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR). Additive interactions of As and OCM with GDM were estimated by determining the relative excess risk due to interaction (RERI).

RESULTS

Of the 396 pregnant women, 89 were diagnosed with GDM. Continuous increases in urinary inorganic As were associated with GDM in the GLMs, with adjusted odds ratios of 2.12 (95% CI: 0.96, 4.71) for As³⁺, and 0.27 (95% CI: 0.07, 0.98) for As⁵⁺. The BKMR in estimating the exposure-response functions showed that As³⁺ and AsB were positively associated with GDM. However, As⁵⁺ showed a negative relationship with GDM. Although the additive interactions between As exposure and OCM indicators were not significant, we found that pregnant women with higher urinary As³⁺ and total As accompanied by lower serum vitamin B₁₂ were more likely to have higher odds of GDM (3.12, 95% CI: 1.32, 7.38 and 3.10, 95% CI: 1.30, 7.38, respectively).

CONCLUSIONS

Our data suggest a positive relation between As³⁺ and GDM but a negative relation between As⁵⁺ and GDM. Potential additive interaction of As and OCM with GDM requires further investigation.

Associations of multiple metals with bone mineral density: A population-based study in US adults

Epidemiologic studies focus on combined effects of multiple metals on bone mineral density (BMD) are scarce. Therefore, this study was conducted to examine associations of multiple metals exposure with BMD. Data of adults aged ≥20 years (n = 2545) from the US National Health and Nutrition Examination Survey (NHANES, 2011-2016) were collected and analyzed. Concentrations of metals were measured in blood (cadmium [Cd], lead [Pb], mercury [Hg], and manganese [Mn]) and serum (copper [Cu], selenium [Se], and zinc [Zn]) using inductively coupled plasma mass spectrometry and inductively coupled plasma dynamic reaction cell mass spectrometry, respectively. The weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR) models were performed to determine the joint effects of multiple metals exposure on lumbar and total BMD. The linear regression analyses showed Pb was negatively associated with BMDs. The WQS regression analyses revealed that the WQS index was inversely related to lumbar (β = -0.022, 95% CI: -0.036, -0.008) and total BMD (β = -0.015, 95% CI: -0.024, -0.006), and Se, Mn, and Pb were the main contributors for the combined effects. Additionally, nonlinear dose-response relationships between Pb, Mn, and Se and BMD, as well as a synergistic interaction of Pb and Mn, were found in the BKMR analyses. Our findings suggested co-exposure to Cd, Pb, Hg, Mn, Cu, Se, and Zn (above their 50th percentiles) was associated with reduced BMD, and Pb, Mn, and Se were the main contributors driving the overall effects.

Predict Health Care Accessibility for Texas Medicaid Gap

Medicaid is a unique approach in ensuring the below poverty population obtains free insurance coverage under federal and state provisions in the United States. Twelve states without expanded Medicaid caused two million people who were under the poverty line into health insecurity. Principal Component-based logistical regression (PCA-LA) is used to consider health status (HS) as a dependent variable and fourteen social-economic indexes as independent variables. Four composite components incorporated health conditions (i.e., “no regular source of care” (NRC), “last check-up more than a year ago” (LCT)), demographic impacts (i.e., four categorized adults (AS)), education (ED), and marital status (MS). Compared to the unadjusted LA, direct adjusted LA, and PCA-unadjusted LA three methods, the PCA-LA approach exhibited objective and reasonable outcomes in presenting an odd ratio (OR). They included that health condition is positively significant to HS due to beyond one OR, and negatively significant to ED, AS, and MS. This paper provided quantitative evidence for the Medicaid gap in Texas to extend Medicaid, exposed healthcare geographical inequity, offered a sight for the Centers for Disease Control and Prevention (CDC) to improve the Medicaid program and make political justice for the Medicaid gap.

Exposome and foetoplacental vascular dysfunction in gestational diabetes mellitus

A balanced communication between the mother, placenta and foetus is crucial to reach a successful pregnancy. Several windows of exposure to environmental toxins are present during pregnancy. When the women metabolic status is affected by a disease or environmental toxin, the foetus is impacted and may result in altered development and growth. Gestational diabetes mellitus (GDM) is a disease of pregnancy characterised by abnormal glucose metabolism affecting the mother and foetus. This disease of pregnancy associates with postnatal consequences for the child and the mother. The whole endogenous and exogenous environmental factors is defined as the exposome. Endogenous insults conform to the endo-exposome, and disruptors contained in the immediate environment are the ecto-exposome. Some components of the endo-exposome, such as Selenium, vitamins D and B₁₂, adenosine, and a high-fat diet, and ecto-exposome, such as the heavy metals Arsenic, Mercury, Lead and Copper, and per- and polyfluoroakyl substances, result in adverse pregnancies, including an elevated risk of GDM or gestational diabesity. The impact of the exposome on the human placenta's vascular physiology and function in GDM and gestational diabesity is reviewed.

Contribution of diet and other factors for urinary concentrations of total arsenic and arsenic species: data for US children, adolescents, and adults

A comprehensive analysis of the associations between the consumptions of 17 food products with urinary concentrations of arsenobetaine, total arsenic, arsenous acid, dimethylarsinic acid (UDMA), monomethylarsonic acid (UMMA), and total inorganic arsenic for US children aged 3-5 years (N = 439), children aged 6-11 years (N = 2139), adolescents aged 12-19 years (N = 2434), and adults aged >= 20 years (N = 10902) was conducted. Data from National Health and Nutrition Examination Survey for 2005-2016 were used for this study. Concentrations of arsenobetaine were as much as > 15 times higher among consumers of fish/shellfish than non-consumers for children aged 6-11 years, > 12 times higher for children aged 3-5 years, > 13 times higher for adolescents, and > 7 times higher for adults. Consumption of rice as opposed to non-consumption of rice was associated with as much as 36.5% higher concentrations of total arsenic, 12.7% higher concentrations of arsenous acid, 43.9% higher concentrations of UDMA, 18.2% higher concentrations of UMMA, and 14.1% higher concentrations of total inorganic arsenic. Thus, consumption of fish/shell fish and rice was associated with higher concentrations of organic/inorganic arsenic. In addition, consumption of alcohol was also found to be associated with higher concentrations of organic/inorganic arsenic. However, consumption of milk and milk products, vegetables, organ and other meats, and nutritional drinks was found to be associated with lower concentrations of organic/inorganic arsenic. Thus, while consumption of several foods is associated with higher concentrations of arsenic, there are also foods whose consumption is associated with decreased concentrations of arsenic. Further studies are needed to identify foods that may lead to decreased concentrations of arsenic and as such arsenic toxicity.

Lead (Pb) exposure and heart failure risk

Lead (Pb) is a heavy metal with widespread industrial use, but it is also a widespread environmental contaminant with serious toxicological consequences to many species. Pb exposure adversely impacts the cardiovascular system in humans, leading to cardiac dysfunction, but its effects on heart failure risk remain poorly elucidated. To better understand the pathophysiological effects of Pb, we review potential mechanisms by which Pb exposure leads to cardiac dysfunction. Adverse effects of Pb exposure on cardiac function include heart failure risk, pressure overload, arrhythmia, myocardial ischemia, and cardiotoxicity. The data reviewed clearly establish that Pb exposure can play an important role in the occurrence and development of heart failure. Future epidemiological and mechanistic studies should be developed to better understand the involvement of Pb exposure in heart failure.

Association between maternal thallium exposure and risk of gestational diabetes mellitus: Evidence from a birth cohort study

BACKGROUND

The adverse effects of TI exposure on pregnant women are still unclear, especially regarding the risk of gestational diabetes mellitus (GDM) Objective: We explored the association between maternal urinary Tl burden and the risk of GDM.

METHODS

A subsample of 1789 pregnant women were enrolled who provided spot urine samples before the diagnostic 75-g oral glucose tolerance test. Urinary Tl concentration was measured using inductively coupled plasma mass spectrometry. Logistic regression and covariance analysis were carried out to estimate the association between Tl exposure and GDM risk.

RESULTS

The median of urinary Tl concentration was 0.382 μg/L or 0.525 μg/g creatinine (CC-Tl). There were 437 (24.4%) participants who were diagnosed with GDM, and the urinary CC-Tl concentrations of pregnant women with GDM were higher than that of pregnant women without GDM [0.548 (0.402, 0.788) vs 0.518 (0.356, 0.724), p = 0.014]. After adjusting for the relevant covariates, an association between urinary Tl concentrations and GDM was found. In comparison to the pregnant women in the lowest quartile of urinary CC-Tl concentration, the pregnant women in the highest quartile had a higher risk of GDM [OR (95% CI) = 1.44 (1.03, 2.02), p-trend = 0.055]. If limited to the pregnant women without family history of diabetes, the results were still robust [OR (95% CI) = 1.59 (1.11, 2.30), p-trend = 0.012].

CONCLUSION

Urinary CC-Tl concentration was associated with GDM among Chinese pregnant women. Our findings provide evidence that moderately high Tl exposure may be a novel risk factor for pregnant women health.

Electronic structure and reactivity of heme bound insulin

Insulin resistance as well as insulin deficiency are said to be principal to the development of type 2 diabetes mellitus (T2Dm). Heme has also been suggested to play an important role in the disease etiology since many of the heme deficiency symptoms constitute the common pathological features of T2Dm. Besides, iron overload, higher heme iron intake and transfusion requiring diseases are associated with a higher risk of T2Dm development. In this study the interaction between these two key components i.e. heme and insulin has been studied spectroscopically under different conditions which include the effect of excess peptide as well as increasing pH. The resultant heme-insulin complexes in their reduced state are found to produce very little partially reduced oxygen species (PROS) on getting oxidized by molecular oxygen. The interaction between insulin and previously reported T2Dm relevant heme-amylin complex were also examined using absorption and resonance Raman spectroscopy. The corresponding data suggest that insulin sequesters heme from heme-amylin to form the much less cytotoxic heme-insulin.

The Relationship Between Heavy Metal Exposure, Trace Element Level, and Monocyte to HDL Cholesterol Ratio with Gestational Diabetes Mellitus

The objective of this study is to assess the levels of heavy metals (cadmium, lead, antimony, mercury, and arsenic), which are also called endocrine-disrupting chemicals, and trace elements (chromium-III, chromium-VI, zinc, copper, and selenium) vs. monocyte to HDL ratio among pregnant women with gestational diabetes mellitus (GDM). A total of 112 pregnant women (60 with GDM and 52 healthy women) were included in this case-control study. Analysis of heavy metals and trace elements were performed in inductively coupled plasma mass spectrometer. Heavy metals (cadmium, lead, antimony, mercury, and arsenic), trace elements (chromium-III, chromium-VI, zinc, copper, and selenium), and metabolic parameters were assessed in both groups. It was determined that the levels of cadmium, lead, antimony, and copper were higher (p < 0.05) and levels of chromium-III, zinc, and selenium were lower (p < 0.05) among the GDM group compared to the control group, whereas there was a statistically insignificant difference between the two groups, regarding the levels of copper, mercury, and arsenic (p > 0.05). Moreover, the monocyte to HDL ratio was higher in the GDM group (p < 0.05), and the insulin resistance was significantly higher as well (p < 0.05). The results of our study demonstrated that environmental factors could be effective in the etiology of GDM. Toxic heavy metals, through inducing Cu, OS, and chronic inflammation, and other trace elements, either directly by impacting insulin secretion or through weakening the body's antioxidant defense system, could play a role in the occurrence of GDM.

Prospective association of metal levels with gestational diabetes mellitus and glucose: A retrospective cohort study from South China

OBJECTIVE

To explore the prospective correlation between serum metals before 24 weeks' gestation and gestational diabetes mellitus (GDM) or glucose in the late second trimester among southern Chinese pregnant women.

METHODS

A total of 8169 pregnant women were included in our retrospective cohort study. Logistic regression was used to investigate the relationships between metals (Manganese [Mn], copper [Cu], lead [Pb], calcium [Ca], zinc [Zn], magnesium [Mg]) and GDM. Quantile regression was performed to detect the shifts and associations with metals and three time-points glucose distribution of oral glucose tolerance test (OGTT) focused on the 10th, 50th, and 90th percentiles. Weighted quantile sum (WQS) regression was used to explore the relationship of metal mixtures and GDM as well as glucose.

RESULTS

Maternal serum concentrations of metals were assessed at mean 16.55 ± 2.92 weeks' gestation. Women with under weight might have 25% decreased risk of GDM for every 50% increase in Cu concentration within the safe limits. A 50% increase in Mn and Zn levels was related to a 0.051 μmol/L (95% CI: 0.033-0.070) and 0.059 μmol/L (95% CI: 0.040-0.079) increase in mean fasting plasma glucose of OGTT (OGTT0), respectively. The magnitude of association with Mn was smaller at the upper tail of OGTT0 distribution, while the magnitude of correlation with Zn was greater at the upper tail. However, there was a 0.012 mmol/L (95% CI: -0.017 to -0.008), 0.028 mmol/L (95% CI: -0.049 to -0.007), and 0.036 mmol/L (95% CI: -0.057 to -0.016) decrease in mean OGTT0 levels for every 50% increase in Pb, Ca, and Mg, respectively. The negative association of Pb, Ca, and Mg was greater at the lower tail of OGTT0 distribution. No significant relationship was observed in Cu and mean OGTT0 level (-0.010 mmol/L, 95% CI: -0.021 to 0.001), however, it showed a protective effect at the upper tail (-0.034 mmol/L, 95% CI: -0.049 to -0.017). No obvious correlation was found between metals and postprandial glucose levels (OGTT1 and OGTT2 from OGTT). The WQS index was significantly related to OGTT0 (P < 0.001). The contribution of Mn (80.19%) to metal mixture index was the highest related to OGTT0, followed by Cu (19.81%).

CONCLUSIONS

Higher Mn and Zn but lower Pb, Ca, and Mg concentrations within a certain range before 24 weeks' gestation might prospectively impair fasting plasma glucose during pregnancy; a greater focus is required on Mn. It could provide early markers of metal for predicting later glucose and suggest implement intervention for pregnant women.

Higher blood cadmium level is associated with greater cognitive decline in rural Chinese adults aged 65 or older

Cadmium (Cd) exposure has been reported to have neurotoxic effects in animal studies and associated with increased Alzheimer's Disease mortality and lower cognitive function in cross-sectional and case-control studies. However, no results from longitudinal studies on Cd and cognitive decline are available. In this prospective cohort study, we recruited 1867 participants aged 65 years or older from rural areas in China, blood Cd and cognitive function were measured at baseline (2010-2012), and 1554 participants completed cognitive function tests during a 3-year follow-up (2013-2015). Cognitive function was evaluated using nine standardized cognitive tests: The Community Screening Instrument for Dementia, the CERAD Word List Learning, Word list recall, IU Story Recall, Animal Fluency Test, Boston Naming Test, Stick Design, Delayed Stick Design and the IU Token Test. Analysis of covariance models and logistic regression models were used to determine the association between Cd and standardized cognitive decline adjusting for covariates. The median blood Cd concentration of this study population was 2.12 μg/L, and the interquartile range was 1.42-4.64 μg/L. Significant association of higher Cd levels with lower cognitive scores were observed in five individual cognitive tests (Delayed Stick Design Test, Boston Naming Test, CERAD Word List Learning Test, Word List Recall Test and IU Story Recall Test) and the composite cognitive score adjusting for multi-covariates at baseline. Higher Cd levels were significantly associated with greater 3-year cognitive decline in Delayed Stick Design Test, Boston Naming Test, IU Token Test, Word List Recall Test and Composite cognitive score. For these cognitive tests, participants in the top two Cd quartile groups had significantly greater decline than those in the lowest Cd quartile group, while the two lowest Cd quartile groups were not significantly different. Our findings suggest that higher Cd exposure is associated with greater cognitive decline in older Chinese adults.

Concentrations of selected arsenic species in urine across various stages of renal function including hyperfiltration

Data (N = 10,590) from National Health and Nutrition Examination Survey for 2005-2016 for US adults aged ≥ 20 years were analyzed to study how concentrations of arsenobetaine (UAB), monomethylarsonic acid (UMMA), dimethylarsenic acid (UDMA), and total arsenic (UAS) in urine vary across the stages of renal function (RF). Data were analyzed over RF-1A (eGFR > 110 mL/min/1.73 m²), RF-1B (eGFR between 90 and 110 mL/min/1.73 m²), RF-2 (eGFR between 60 and 90 mL/min/1.73 m²), RF-3A (eGFR between 45 and 60 mL/min/1.73 m²), and RF-3B/4 (eGFR between 15 and 45 mL/min/1.73 m²). Adjusted geometric mean (AGM) concentrations of the total population, males, and females for UAS, UAB, and UDMA were observed to follow inverted U-shaped distributions with points of inflection located at RF-3A. For example, adjusted concentrations for the total population for UAS were 8.8, 8.8, 9.5, 11.7, and 9.6 μg/L for those in RF-1A, RF-1B, RF-2, RF-3A, and RF-3B/4 respectively. While statistically significant differences were only occasionally observed, males, in general, had lower AGMs than females for UAS and UDMA, but females had lower AGMs than males for UAB. Among the various racial/ethnic groups, non-Hispanic whites had the lowest adjusted concentrations of all four arsenic variables. Adjusted levels of all four arsenic variables were observed to decrease over survey years of 2005-2006 through 2015-2016. However, statistical significance was not necessarily reached for all RF stages. Smoking was associated with reduced levels of four arsenic variables over RF-1A through RF-2. Diabetes was associated with increased levels of UMMA and UDMA at RF-2.

Significant association between blood lead (Pb) level and haemoglobin A1c in non-diabetic population

Although many heavy metals are necessary for normal biological function, a subset of heavy metals have no role in human physiology, such as lead (Pb) and arsenic (As). Such elements have deleterious effects on physiology and be associated with the incidence of diabetes and related metabolic syndromes. Haemoglobin A1c (HbA1c) is not only a useful diagnostic and prognostic parameter in patients with diabetes, but it is also helpful in prediction of future diabetic risk in non-diabetic patients. However, no studies have evaluated the relationship between heavy metal concentration and HbA1c in non-diabetic patients. Therefore, the present study was designed to address this issue. We performed surveys for general populations living in southern Taiwan from June 2016 to September 2018. All participants received face-to-face interviews, laboratory tests, and measurements of weight and height, waist circumference, heart rate, and systolic and diastolic blood pressures. HbA1c was positively associated with Log blood Pb, after adjustments for age, body mass index, fasting blood glucose, total cholesterol, and triglyceride. Additionally, a Log 1 μg/dL increase in Pb was associated with a small (0.819 mmol/mol, 95% confidence interval = 0.072-1.566) increase in HbA1c (P =  0.032). No association with HbA1c was observed for urine nickel, chromium, manganese, As, copper, and cadmium in the multivariable analysis. In conclusion, after adjusting for important clinical parameters, Log blood Pb was positively associated with HbA1c in our non-diabetic population. This finding implies that high blood Pb might have the potential to predict future diabetic risk in non-diabetic populations. Further prospective studies are necessary to validate this issue.

Temporal trends of urinary mercury in Chinese people from 1970s to 2010s: A review

Mercury (Hg) is one of the most toxic heavy metals. It can migrate around the globe and magnify through the food chain, ultimately harming human health. Urinary Hg reflects recent exposure of Hg, which reflects the status of environmental contamination by Hg. This review summarized the levels and presented temporal trends of urinary Hg in Chinese people (both the general public and the occupationally exposed people) reported from 1970s to 2010s. It was found that urinary Hg levels in 92.3% of the reported population were less than the reference value (10.0 µg/L) recommended by Chinese health authority, while 76.9% were less than the reference value (4.0 µg/L) recommended by World Health Organization (WHO) in the general public in China. For the temporal trend from 1970s to 2010s, the urinary Hg levels in the general public in China were found to decrease gradually. In the occupationally exposed people, the urinary Hg levels generally exceeded the reference value (10.0 µg/L) for the general public, and about half of them were higher than the occupational exposure limit (35.0 µg/g creatinine) set by Chinese Occupational Health Standard (WS/T 265 - 2006). From 1970s to 2010s, the urinary Hg levels in occupationally exposed population increased first and then decreased slowly. Hg miners in Guizhou were found to have the highest urinary Hg levels, while workers in Anhui, Chongqing, Qinghai and Shanxi also had high levels of urinary Hg. In all, the urinary Hg levels in both the general public and the occupationally exposed people decreased from 1970s to 2010s, especially in recent decades. Attention should be paid to occupationally exposed people since high levels of urinary Hg were found in them. The message provided in this review can help better understand the situation of Hg burden in Chinese people and lay a basis for the coming effectiveness evaluation on the implementation of Minamata Convention on Mercury. Capsule abstract: The urinary Hg levels in both the general public and the occupationally exposed people in China are decreasing.

Early Pregnancy Exposure to Rare Earth Elements and Risk of Gestational Diabetes Mellitus: A Nested Case-Control Study

OBJECTIVE

The extensive use of rare earth elements (REEs) in many technologies was found to have effects on human health, but the association between early pregnancy exposure to REEs and gestational diabetes mellitus (GDM) is still unknown.

METHODS

This nested case-control study involved 200 pregnant women with GDM and 200 healthy pregnant women from the Peking University Birth Cohort in Tongzhou. We examined the serum concentrations of 14 REEs during early pregnancy and analyzed their associations with the risk of GDM.

RESULTS

When the elements were considered individually in the logistic regression model, no significant associations were found between REEs and GDM, after adjusting for confounding variables (P > 0.05). In weighted quantile sum (WQS) regression, each quartile decrease in the mixture index for REEs resulted in a 1.67-fold (95% CI: 1.12-2.49) increased risk of GDM. Neodymium (Nd), Praseodymium (Pr), and Lanthanum (La) were the most important contributors in the mixture.

CONCLUSION

The study findings indicated that early pregnancy exposure to lower levels of REE mixture was associated with an increased risk of GDM, and Nd, Pr, and La exhibited the strongest effects in the mixture.

Epigenetic alternations of microRNAs and DNA methylation contribute to gestational diabetes mellitus

This study aimed to identify epigenetic alternations of microRNAs and DNA methylation for gestational diabetes mellitus (GDM) diagnosis and treatment using in silico approach. Data of mRNA and miRNA expression microarray (GSE103552 and GSE104297) and DNA methylation data set (GSE106099) were obtained from the GEO database. Differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs) and differentially methylated genes (DMGs) were obtained by limma package. Functional and enrichment analyses were performed with the DAVID database. The protein‐protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. Simultaneously, a connectivity map (CMap) analysis was performed to screen potential therapeutic agents for GDM. In GDM, 184 low miRNA‐targeting up‐regulated genes and 234 high miRNA‐targeting down‐regulated genes as well as 364 hypomethylation–high‐expressed genes and 541 hypermethylation–low‐expressed genes were obtained. They were mainly enriched in terms of axon guidance, purine metabolism, focal adhesion and proteasome, respectively. In addition, 115 genes (67 up‐regulated and 48 down‐regulated) were regulated by both aberrant alternations of miRNAs and DNA methylation. Ten chemicals were identified as putative therapeutic agents for GDM and four hub genes (IGF1R, ATG7, DICER1 and RANBP2) were found in PPI and may be associated with GDM. Overall, this study identified a series of differentially expressed genes that are associated with epigenetic alternations of miRNA and DNA methylation in GDM. Ten chemicals and four hub genes may be further explored as potential drugs and targets for GDM diagnosis and treatment, respectively.

Maternal Arsenic Exposure and Gestational Diabetes: A Systematic Review and Meta-Analysis

Gestational diabetes mellitus (GDM) is a metabolic complication associated with adverse outcomes for mother and fetus. Arsenic (As) exposure has been suggested as a possible risk factor for its development. The aim of this meta-analysis was to provide a comprehensive overview of published evidence on the association between As and GDM. The systematic search from PubMed, MEDLINE, and Scopus was limited to full-length manuscripts published in peer-reviewed journals up to April 2020, identifying fifty articles. Ten studies met the inclusion criteria, nine for quantitative synthesis with a total of n = 1984 GDM cases. The overall pooled risk was 1.56 (95% Confidence Interval - CI = 1.23, 1.99) with moderate heterogeneity (χ2 = 21.95; I2% = 64). Several differences among the included studies that may account for heterogeneity were investigated. Stratification for exposure indicator confirmed a positive association for studies assessing urine As. A slightly higher risk was detected pooling studies based in Asia rather than in North America. Stratification for GDM diagnostic criteria showed higher risks when diagnosis was made according to the Canadian Diabetes Association (CDA-SOGC) or World Health Organization (WHO) criteria, whereas a lower risk was observed when adopting the American Diabetes Association (ADA) criteria. These results provide additional evidence for a possible association between As exposure and GDM, although the data need to be interpreted with caution due to heterogeneity.

Repeated measures of prenatal thallium exposure and placental inflammatory cytokine mRNA expression: The Ma'anshan birth cohort (MABC) study

Thallium (Tl), a ubiquitous environmental toxicant, can cross the placental barrier during pregnancy. However, the effects of prenatal Tl exposure on placental function are currently unclear. Based on the Ma'anshan Birth Cohort study, we examined whether long-term prenatal Tl exposure was associated with placental inflammation. Tl concentrations were quantified in serum samples (n = 7050) from 2515 pregnancy during each trimester, placental inflammatory cytokine mRNA expression was assessed in 2519 placenta tissues. Geometric mean values of serum Tl concentrations were 63.57, 63.63 and 48.71 ng/L for the first, second and third trimesters, respectively. After adjustment for potential confounders, serum Tl concentration was positively associated with CD68 (β: 0.30; 95% CI: 0.05, 0.56) in the first trimester and TNF-α (β: 0.12; 95% CI: 0.01, 0.23), IL-6 (β: 0.15; 95% CI: 0.05, 0.25) and CD68 (β: 0.25; 95% CI: 0.10, 0.39) in the third trimester, however was negatively associated with IL-4 (β: -0.21; 95% CI: -0.41, -0.01) and CD206 (β: -0.23; 95% CI: -0.45, -0.02) in the first trimester. Repeated measures analysis showed that TNF-α, IL-6 and CD68 increased by 0.11 (95% CI: 0.01, 0.21), 0.12 (0.15, 95% CI: 0.05, 0.25), 0.22 (95% CI: 0.10, 0.39), respectively, with each 1ln-transformed Tl increase in total samples. Gender-specific analyses revealed that these associations were largely driven by male offspring. In addition, immunohistochemistry revealed that nuclear NF-κB p65 expression increased in placenta tissue. The results of this prospective cohort study provide longitudinal evidence that prenatal Tl exposure induces a placental inflammatory response in the Chinese population.