The present study aims to determine the associations of multiple plasma metal levels and plasma microRNAs (miRNAs) with diabetes risk, and further explore the mediating effects of plasma miRNAs on the associations of plasma metal with diabetes risk. We detected plasma levels of 23 metals by inductively coupled plasma mass spectrometry (ICP-MS) among 94 newly diagnosed and untreated diabetic cases and 94 healthy controls. The plasma miRNAs were examined by microRNA Array screening and Taqman real-time PCR validation among the same study population. The multivariate logistic regression models were employed to explore the associations of plasma metal and miRNAs levels with diabetes risk. Generalized linear regression models were utilized to investigate the relationships between plasma metal and plasma miRNAs, and mediation analysis was used to assess the mediating effects of plasma miRNAs on the relationships between plasma metals and diabetes risk. Plasma aluminum (Al), titanium (Ti), copper (Cu), zinc (Zn), selenium (Se), rubidium (Rb), strontium (Sr), barium (Ba), and Thallium (Tl) levels were correlated with elevated diabetic risk while molybdenum (Mo) with decreased diabetic risk (P < 0.05 after FDR multiple correction). MiR-122–5p and miR-3141 were positively associated with diabetes risk (all P < 0.05). Ti, Cu, and Zn were positively correlated with miR-122–5p (P = 0.001, 0.028 and 0.004 respectively). Ti, Cu, and Se were positively correlated with miR-3141 (P = 0.003, 0.015, and 0.031 respectively). In addition, Zn was positively correlated with miR-193b-3p (P = 0.002). Ti was negatively correlated with miR-26b-3p (P = 0.016), while Mo and miR-26b-3p were positively correlated (P = 0.042). In the mediation analysis, miR-122–5p mediated 48.0% of the association between Ti and diabetes risk. The biological mechanisms of the association are needed to be explored in further studies.

Associations between environmental metals and chemicals and adverse human health effects have emerged recently, but the links among environmental metals and respiratory diseases are less studied. The aim of this study was to assess 14 urinary metals (cadmium, barium, cobalt, molybdenum, mercury, cesium, manganese, antimony, lead, tin, strontium, tungsten, thallium, and uranium), seven species of arsenic (arsenous acid, arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid, monomethylarsonic acid, and total arsenic) and seven polycyclic aromatic hydrocarbon (PAH) (1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 2 & 3-hydroxyphenanthrene) compounds’ concentrations in urine and the correlation with chronic obstructive pulmonary disease (COPD) in the adult US population. A cross-sectional analysis using the 2013–2014 and 2015–2016 National Health and Nutrition Examination Survey (NHANES) dataset was conducted. Self-questionnaires related to COPD criteria were used to identify the COPD cases. The correlation between urinary metals and PAH compounds and COPD was calculated. The total study population analyzed included 2885 adults aged 20 years and older. Seven types of urinary PAHs including 1-hydroxynaphthalene [odds ratio (OR): 1.832, 95% confidence interval (CI): 1.210, 2.775], 2-hydroxynaphthalene [OR: 3.361, 95% CI: 1.519, 7.440], 3-hydroxyfluorene [OR: 2.641, 95% CI: 1.381, 5.053], 2-hydroxyfluorene [OR: 3.628, 95% CI: 1.754, 7.506], 1-hydroxyphenanthrene [OR: 2.864, 95% CI: 1.307, 6.277], 1-hydroxypyrene [OR: 4.949, 95% CI: 2.540, 9.643] and 2 & 3-hydroxyphenanthrene [OR: 3.487, 95% CI: 1.382, 8.795] were positively associated with COPD. Urinary cadmium [OR: 12.382, 95% CI: 4.459, 34.383] and tin [OR: 1.743, 95% CI: 1.189, 2.555] showed positive associations with increased odds of COPD. The other types of urinary metals were not associated with COPD. The study observed that urinary PAHs, cadmium, and tin are significantly associated with COPD.

Barium (Ba) is ubiquitous in the environment, and humans are primarily exposed to it through ingestion of drinking water. Previous studies focused on the exposure to lead, cadmium, and arsenic, but have not focused on exposure to Ba. Recent studies found a significant association between Ba exposure and elevated blood pressure in pregnant women and adults. However, there are no studies regarding the effect of Ba exposure on blood pressure in children and adolescents, and the potential biological mechanisms remain unclear. We evaluated the associations between urinary Ba and systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) among 8- to 17-year-old participants (n = 3707) of the 2003–2018 National Health and Nutrition Examination Survey. Furthermore, the potential roles of inflammation in these associations were explored. Weighted linear regression was used to analyze the association between urinary Ba and blood pressure, and mediation analyses were used to estimate the potential role of white blood cell count (WBC) in these associations. Quantile g-computation models were used to explore the effect of co-exposure to Ba and other metals on blood pressure. After adjusting for covariates, a two-fold increase in urinary Ba concentration was associated with a 0.41 (95% CI 0.12, 0.70) mmHg increase in SBP, a 1.04 (95% CI 0.55, 1.53) mmHg increase in PP, but a −0.63 (95% CI −1.04, −0.22) mmHg decrease in DBP. WBC significantly mediated 6% of the association between urinary Ba and SBP. Quantile g-computation models suggested that urinary Ba was the main contributor to the elevation of SBP and PP in the urinary metal mixture. Our findings revealed that exposure to Ba was associated with elevated SBP and PP among children and adolescents. Inflammation may play an important role in the associations of Ba exposure with SBP.

Pollution of the aquatic ecosystem due to different trace elements has become a global concern which has raised health-related issues for both aquatic and human life. Industrial and agricultural water run-off drained into the rivers and deposit trace elements in water, sediments and planktons. This study was designed to calculate the burden of trace elements such as aluminium (Al), arsenic (As), barium (Ba), and lead (Pb) in the river water of Punjnad Headworks, Bahawalpur, Punjab, Pakistan. Samples were collected from surface water, bed sediments and planktons during autumn, winter and spring seasons (September 2018 to May 2019). The results showed that the concentration of Pb was highest in surface water (453.87 mg L⁻¹), while that of Al was highest in sediments (370.24 µg g⁻¹) and plankton (315.05 µg g⁻¹). A significant difference was found in metal concentrations among surface water, bed sediments and plankton at different sampling stations during various seasons. Importantly, the Expᵢₙg (0.71, 1.23⁻³, 0.34, 0.02 for Pb, As, Al, and Ba, respectively) and Expdₑᵣₘ (7.09⁻⁸, 1.23¹⁰, 3.42⁻⁸, and 2.48⁻⁹ for Pb, As, Al, and Ba, respectively) for trace elements were below 1.0 suggesting non-significant adverse effects of trace elements on human health. This study provided better understanding of various pollutants and their concentrations in water sources at the studied location.

The chemical characteristic of flowback fluid from hydraulic fracturing for shale gas exploration/production in various localizations is presented. The results of statistical analysis have shown that variability in the chemical composition of these fluids is statistically significant and depends on the time difference between fracturing process and flowback sampling as well as sampling spot within the installation for flowback collection. Parameters which depend on sampling schedule (time and spot of sampling) are as follows: electrical conductivity and concentration of ammonia, boron, barium, calcium, lithium, sodium, magnesium, manganese, sodium, strontium, silicate, bromide, and chloride. Independent parameters are pH, total organic carbon (TOC), concentration of potassium, and iron. The ranges of the values of the characteristic parameters were determined, taking into account the representativeness of the samples, supported by statistical tests. The methods for the reuse of flowback fluids in terms of chemical composition are presented.

Congenital heart defects (CHDs) are one of the major causes of death in infants and young children, and heavy metal exposure during pregnancy is one of the possible risk factors. However, the effect of heavy metal exposure on CHDs is still controversial. We searched English (PubMed, Web of Science) and Chinese (CNKI and WanFang database) databases for relevant articles. The summarized effect sizes and 95% confidence intervals (CIs) were calculated by pooling estimates using the random-effects model. Egger’s test was used to estimate publication bias. Heterogeneity among studies was indicated by p-values and I². Finally, we conducted subgroup analyses to elucidate the causes of heterogeneity. Thirteen studies were included in this meta-analysis. A positive association between maternal exposure to heavy metals and CHDs was found. Pooling odds ratios (ORs) for arsenic, cadmium, mercury, and lead were 2.12, 1.30, 1.22, and 2.30, respectively for total CHDs. Regarding CHD subtypes, arsenic was associated with an increased risk of septal defects (OR: 1.82), barium with left ventricular outflow tract obstruction (LVOTO) (OR: 1.15) and septal defects (OR: 1.21), and lead with conotruncal defects (OR: 2.34) and LVOTO (OR: 1.93). A heterogeneous relationship was found between studies using different methods of measurement, which were mainly due to differences in actual exposure levels to heavy metals. This meta-analysis suggests significant associations between arsenic, cadmium, mercury, and lead exposure during pregnancy and an increased risk of specific CHDs in offspring. These findings underscore the importance of heavy metal exposure during pregnancy in the risk of CHDs in offspring.

Human beings are exposed to heavy metals through various ways in daily life. However, the effect of heavy metal mixtures on muscle strength in children and adolescents remains unclear. We aimed to investigate the relationship of exposure to heavy metal mixtures (barium, cadmium, cobalt, manganese, molybdenum, lead, antimony, strontium, tin, thallium, tungsten, uranium, and cesium) with muscle strength in children and adolescents. A total of 1357 (boys, 50.8%) participants aged between 8 and 17 were extracted from the National Health and Nutrition Examination Surveys 2011–2014. Urine metals were measured by inductively coupled plasma-mass spectrometry. Muscle strength was measured through a grip test using a handgrip dynamometer. Weighted quantile sum regression was performed to estimate the mixture effect of urinary metals on muscle strength. After adjusting for potential confounders, comparing participants in the highest versus lowest quartiles of cobalt, molybdenum, lead, antimony, strontium, thallium, and cesium, the handgrip strength decreased by − 4.48 kg (95% CI: − 6.93, − 2.03), − 6.13 kg (− 8.76, − 3.51), − 2.26 kg (− 4.22, − 0.30), − 2.38 kg (− 4.68, − 0.08), − 2.29 kg (− 4.45, − 0.13), − 4.78 kg (− 7.13, − 2.44), and − 5.68 kg (− 9.20, − 2.17), respectively. Furthermore, exposure to a mixture of metals were also significantly associated with decreased muscle strength (β: − 2.62 kg; 95% CI: − 3.71, − 1.54). Findings from the present study suggest that higher heavy metal exposure and the exposure levels of a mixture of metals in urine are inversely related to handgrip strength, implying that children’s grip strength is not entirely explained by energy intake or lack of exercise, but may be related to environmental pollutants.

Chemical exposure of heavy metals in children is of particular concern. However, using heavy metal-contaminated toys can threaten the life and well-being of children. Therefore, quality control of toys for avoiding children exposure to potentially toxic metals is important. The investigation of potentially toxic metals (arsenic, barium, antimony, cadmium, chromium, mercury, lead, selenium) in toys was performed in present study. A total number of 150 popular cheap priced plastic toy samples were purchased from the eight metropolitan and most visited provinces in Iran and analyzed by atomic absorption spectrophotometer for arsenic, barium, antimony cadmium, chromium, mercury, lead, and selenium. As results showed As, Ba, Cd, Cr, Hg, Pb, Sb, and Se respectively were in the range of 0–0.9 mg/kg, 0.3–5 mg/kg, 0–3.1 mg/kg, 0.04–4.8 mg/kg, 0–0.03 mg/kg, 0.22–11.7 mg/kg, 0–1.2 mg/kg, and 0.03–1.1 mg/kg. Cadmium was higher than the European standard in Kurdistan province. The highest amount of mercury was also observed in Tehran. The highest amount of lead, selenium, and antimony was detected in Qom province. The results showed that all the toxic elements in the collected toys were within the permissible limit. Furthermore, market monitoring is needed to control toys safety on a large scale in metropolitan cities like Qom province.

Metals, arsenic, and polycyclic aromatic hydrocarbons (PAHs) have all been linked to respiratory diseases. Chronic bronchitis, which is a form of chronic obstructive pulmonary disease (COPD), is a major public health concern and source of morbidity and mortality in the US. The purpose of this study was to analyze the correlation of 14 urinary metals (antimony, barium, cadmium, cesium, cobalt, lead, manganese, mercury, molybdenum, strontium, thallium, tin, tungsten, uranium), seven species of arsenic, and seven forms of polycyclic aromatic hydrocarbon (PAH) concentrations and chronic bronchitis in the US population. A cross-sectional analysis using three datasets from the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2016 in adults, aged 20 years and older. Chronic bronchitis was determined using a self-questionnaire from the NHANES dataset. A specialized weighted complex survey design analysis package was used to analyze NHANES data. Multivariate logistic regression models were used to determine the correlation between urinary metals, arsenic, PAHs, and chronic bronchitis. Models were adjusted for lifestyle and demographic factors. A total of 4186 participants were analyzed; 49.8% were female and 40.5% were non-Hispanic White. All seven types of PAHs showed a positive association with chronic bronchitis (1-hydroxynaphthalene odds ratio (OR): 1.559, 95% confidence interval (CI): 1.271–1.912; 2-hydroxynaphthalene OR: 2.498, 95% CI: 1.524–4.095; 3-hydroxyfluorene OR: 2.752, 95% CI: 2.100–3.608; 2-hydroxyfluorene OR: 3.461, 95% CI: 2.438–4.914; 1-hydroxyphenanthrene OR: 2.442, 95% CI: 1.515–3.937; 1-hydroxypyrene OR: 2.828, 95% CI: 1.728–4.629; 2 & 3-hydroxyphenanthrene OR: 3.690, 95% CI: 2.309–5.896). Of the metals, only urinary cadmium showed a statistically significant positive association (OR: 2.435, 95% CI: 1.401–4.235) with chronic bronchitis. No other metals or arsenic were correlated with chronic bronchitis. Seven forms of urinary PAHs, cadmium, and several demographic factors were associated with chronic bronchitis.