Concentration of Selected Metals in Whole Blood, Plasma, and Urine in Short Stature and Healthy Children

Associations between metal(loid) exposure with overweight and obesity and abdominal obesity in the general population: A cross-sectional study in China

Previous studies have revealed links between metal(loid)s and health problems; however, the link between metal(loid)s and obesity remains controversial. We evaluated the cross-sectional association between metal(loid) exposure in whole blood and obesity among the general population. Vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), antimony (Sb), thallium (T1), and lead (Pb) were measured in 3029 subjects in Guangdong Province (China) using ICP-MS. The prevalence of overweight and obesity (OWO) and abdominal obesity (AOB) was calculated according to body mass index (BMI) and waist circumference (WC), respectively. Multivariate analysis showed that elevated blood Cu, Cd, and Pb levels were inversely associated with the risk of OWO, and these associations were confirmed by a linear dose-response relationship. Elevated blood Co concentration was associated with a decreased risk of AOB. A quantile g-computation approach showed a significantly negative mixture-effect of 13 metal(loid)s on OWO (OR: 0.96; 95% CI: 0.92, 0.99). Two metals-Ni and Mo-were inversely associated with the risk of OWO but positively associated with AOB. We cross-grouped the two obesity measurement types and found that the extremes of metal content were present in people with AOB only. In conclusion, blood Cu, Mo, Ni, Cd, and Pb were inversely associated with the risk of OWO. The presence of blood Co may be protective, while Ni and Mo exposure might increase the risk of AOB. The association between metal(loid) exposure and obesity warrants further investigation in longitudinal cohort studies.

Association Between Heavy Metals Exposure and Height in Chinese Preschoolers

OBJECTIVES

This study aimed to explore the association between multiple metals' exposure and children's height.

METHODS

We collected urine samples and physical measurement data of 1477 preschoolers in China. Children's actual height was measured, and whether reached target height was also assessed. Logistic regression analysis was performed to explore the association between heavy metals and height. The least absolute shrinkage and selection operator regression was used to select the urinary metals, which were highly correlated.

RESULTS

In the single-metal model after adjusting for potential confounders, urinary iron, aluminum, nickel, chrome, titanium, vanadium, selenium, rubidium, and thallium levels were negatively associated with actual height. Urinary iron, aluminum, nickel, and chrome concentrations were also negatively associated with target height.

CONCLUSIONS

The findings suggested that some urinary metal exposure might be associated with height in preschoolers.

Epidemiological evidence for the effect of environmental heavy metal exposure on the immune system in children

Heavy metals exist widely in daily life, and exposure to heavy metals caused by environmental pollution has become a serious public health problem worldwide. Due to children's age-specific behavioral characteristics and imperfect physical function, the adverse health effects of heavy metals on children are much higher than in adults. Studies have found that heavy metal exposure is associated with low immune function in children. Although there are reviews describing the evidence for the adverse effects of heavy metal exposure on the immune system in children, the summary of evidence from epidemiological studies involving the level of immune molecules is not comprehensive. Therefore, this review summarizes the current epidemiological study on the effect of heavy metal exposure on childhood immune function from multiple perspectives, emphasizing its risks to the health of children's immune systems. It focuses on the effects of six heavy metals (lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), nickel (Ni), and manganese (Mn)) on children's innate immune cells, lymphocytes and their subpopulations, cytokines, total and specific immunoglobulins, and explores the immunotoxicological effects of heavy metals. The review finds that exposure to heavy metals, particularly Pb, Cd, As, and Hg, not only reduced lymphocyte numbers and suppressed adaptive immune responses in children, but also altered the innate immune response to impair the body's ability to fight pathogens. Epidemiological evidence suggests that heavy metal exposure alters cytokine levels and is associated with the development of inflammatory responses in children. Pb, As, and Hg exposure was associated with vaccination failure and decreased antibody titers, and increased risk of immune-related diseases in children by altering specific immunoglobulin levels. Cd, Ni and Mn showed activation effects on the immune response to childhood vaccination. Exposure age, sex, nutritional status, and co-exposure may influence the effects of heavy metals on immune function in children.

Fluorescence "Turn-Off" and Colorimetric Sensor for Fe2+, Fe3+, and Cu2+ Ions Based on a 2,5,7-Triarylimidazopyridine Scaffold

Two cyanoimidazopyridine-based sensors (SS1 and SS2) were explored for the colorimetric and fluorometric detection of Fe²⁺, Fe³⁺, and Cu²⁺ ions in the semi-aqueous medium. The "turn-off" fluorescence response of both sensors to these ions was due to the restriction in internal charge transfer. Job's plot and semi-empirical calculations revealed that SS1 and SS2 complexed with Cu²⁺ ions in a 1:1 ratio and Fe^2+/3+ ions in a 2:1 ratio, respectively. The sensors were found to have high binding constant (K _a) values and low detection limit values. FMO analysis using the semi-empirical quantum mechanics method revealed the decrease in energy gap after complexation with metal ions. Sensor-coated filter paper strips were prepared and analyzed, where the color changes in the strips could be utilized for the real-time detection of Fe²⁺, Fe³⁺, and Cu²⁺ ions.

Colorimetric determination of cysteine and copper based on the peroxidase-like activity of Prussian blue nanocubes

Prussian blue nanocubes were synthesized via a hydrothermal method. Significantly, the redox couple Ni3+/Ni2+ provided rich oxidation and reduction reactions, which enhance catalytic activity. Furthermore, PBNCs mimic peroxidase activity which could oxidise colourless tetramethyl benzidine (TMB) to a blue colour (TMB+) in the presence of H2O2. Thus, it can be used as a colorimetric sensing platform for detecting cysteine and Cu2+. The addition of cysteine to a TMB + PBNCs sensing system decreases the intensity of the blue colour in the solution with a decrease in the absorption peak at 652 nm in the UV visible spectrum. Subsequently, the addition of Cu2+ into the TMB + PBNCs + Cys sensing system increases the intensity of the blue colour due to complex formation of Cu and cysteine. Therefore, the change in intensity of the blue colour of TMB is directly proportional to the concentration of Cys and Cu2+. As a result, this sensing system is highly sensitive and selective with an effective low detection limit of 0.002 mM for cysteine and 0.0181 mM for Cu2+. Furthermore, this method was applied to the detection of cysteine and copper in spiked real samples and gave satisfactory results.

High-Sensitivity Sensing of Divalent Copper Ions at the Single Upconversion Nanoparticle Level

Single-nanoparticle-level sensing allows us to measure individual molecular interactions and probe environmental stimuli at nanometer-scale resolution. Despite these premises, limited success has been met hitherto due to the demanding challenge to distinguish a dimmed signal from a noisy background. Here, we describe an approach for high-sensitivity single-nanoparticle-level sensing of divalent copper (Cu²⁺) ions through near-infrared-to-visible upconversion luminescence against a near-null background. This nanosensor utilizes ytterbium- (Yb³⁺) and erbium (Er³⁺)-doped sodium yttrium fluoride (NaYF₄) upconversion nanoparticles (UCNPs) (maximal emission at 540 nm when excited at 980 nm) as an energy donor, of which the surface attaches Cu²⁺-dependent DNAzymes labeled with BHQ1 dye (Black Hole Quencher 1, maximal absorption at 548 nm) as energy acceptors. Adding a hint amount of Cu²⁺ ions resulted in the cleavage of a BHQ1-containing moiety in DNAzymes, thus turning on upconversion luminescence for sensitive detection. Indeed, this approach allows us to perform single-nanoparticle-level detection of Cu²⁺ ions with extraordinary signal-to-noise ratios (SNRs, >277) for all measured concentrations that cover 3 orders of magnitude (from sub-nM to μM). Importantly, a limit of detection of 220 pM was achieved, about sevenfold lower than the one at the ensemble level. Moreover, a stochastic particle-to-particle sensing behavior was also identified, featuring single-nanoparticle-level detection. This work untaps the usage of UCNPs for high-sensitivity single-nanoparticle-level biosensing.

The evaluation of heavy metals in transylvania, as predictor for the health status of the exposed population

It is well known and proven that heavy metal contamination of the soils can severely affect the health of the people living in the contaminated areas given the ease with which trace elements can enter the human body. In addition-to agricultural crop depreciation as well as soil erosion, soil pollution can negatively affect the natural function of ecosystems. While certain heavy metals in high doses can be harmful to the body, others such as cadmium, mercury, lead, chromium, silver and arsenic in minimal amounts have delusional effects on the body, causing acute and chronic intoxication. Our research is focused on the identification of heavy metals from the soil (O, Al, Ca, Cu, Fe, K, Mg, Na, P, Pb, Si, Ti, Zn) in 3 areas in Transylvania where factories were in operation, using 4 methods: UV-VIS spectrometry, AAS, SEM-EDAX and X-ray diffractions. High levels of very toxic trace elements such as lead, aluminum, cadmium were found near the studied areas, especially using SEM-EDAX and AAS methods. Knowledge on the soil concentration of TEs, the time exposure and the side effects can lead us to predict the health status of the exposed population. In our study, by determinating the concentration of TEs we set out to formulate a prediction on the health status of the exposed population using literature data.

Vitamin D Status in Children With Short Stature: Accurate Determination of Serum Vitamin D Components Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry

OBJECTIVE

Vitamin D is critical for calcium and bone metabolism. Vitamin D insufficiency impairs skeletal mineralization and bone growth rate during childhood, thus affecting height and health. Vitamin D status in children with short stature is sparsely reported. The purpose of the current study was to investigate various vitamin D components by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) to better explore vitamin D storage of short-stature children in vivo.

METHODS

Serum circulating levels of 25-hydroxyvitamin D2 [25(OH)D2], 25-hydroxyvitamin D3 [25(OH)D3], and 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3, C3-epi] were accurately computed using the LC-MS/MS method. Total 25(OH)D [t-25(OH)D] and ratios of 25(OH)D2/25(OH)D3 and C3-epi/25(OH)D3 were then respectively calculated. Free 25(OH)D [f-25(OH)D] was also measured.

RESULTS

25(OH)D3 and f-25(OH)D levels in short-stature subgroups 2 (school age: 7~12 years old) and 3 (adolescence: 13~18 years old) were significantly lower compared with those of healthy controls. By contrast, C3-epi levels and C3-epi/25(OH)D3 ratios in all the three short-stature subgroups were markedly higher than the corresponding healthy cases. Based on cutoff values developed by Endocrine Society Recommendation (but not suitable for methods 2 and 3), sufficient storage capacities of vitamin D in short-stature subgroups 1, 2, and 3 were 42.8%, 23.8%, and 9.0% as determined by Method 3 [25(OH)D2/3+25(OH)D3], which were lower than those of 57.1%, 28.6%, and 18.2% as determined by Method 1 [25(OH)D2+25(OH)D3+C3-epi] and 45.7%, 28.5%, and 13.6% as determined by Method 2 [25(OH)D2/3+25(OH)D3+C3-epi]. Levels of 25(OH)D2 were found to be weakly negatively correlated with those of 25(OH)D3, and higher 25(OH)D3 levels were positively correlated with higher levels of C3-epi in both short-stature and healthy control cohorts. Furthermore, f-25(OH)D levels were positively associated with 25(OH)D3 and C3-epi levels in children.

CONCLUSIONS

The current LC-MS/MS technique can not only separate 25(OH)D2 from 25(OH)D3 but also distinguish C3-epi from 25(OH)D3. Measurement of t-25(OH)D [25(OH)D2+25(OH)D3] alone may overestimate vitamin D storage in children, and short-stature children had lower vitamin D levels compared with healthy subjects. Ratios of C3-epi/25(OH)D3 and 25(OH)D2/25(OH)D3 might be alternative markers for vitamin D catabolism/storage in short-stature children. Further studies are needed to explore the relationships and physiological roles of various vitamin D metabolites.

Update of the risk assessment of nickel in food and drinking water

The European Commission asked EFSA to update its previous Opinion on nickel in food and drinking water, taking into account new occurrence data, the updated benchmark dose (BMD) Guidance and newly available scientific information. More than 47,000 analytical results on the occurrence of nickel were used for calculating chronic and acute dietary exposure. An increased incidence of post-implantation loss in rats was identified as the critical effect for the risk characterisation of chronic oral exposure and a BMDL 10 of 1.3 mg Ni/kg body weight (bw) per day was selected as the reference point for the establishment of a tolerable daily intake (TDI) of 13 μg/kg bw. Eczematous flare-up reactions in the skin elicited in nickel-sensitised humans, a condition known as systemic contact dermatitis, was identified as the critical effect for the risk characterisation of acute oral exposure. A BMDL could not be derived, and therefore, the lowest-observed-adverse-effect-level of 4.3 μg Ni/kg bw was selected as the reference point. The margin of exposure (MOE) approach was applied and an MOE of 30 or higher was considered as being indicative of a low health concern. The mean lower bound (LB)/upper bound (UB) chronic dietary exposure was below or at the level of the TDI. The 95th percentile LB/UB chronic dietary exposure was below the TDI in adolescents and in all adult age groups, but generally exceeded the TDI in toddlers and in other children, as well as in infants in some surveys. This may raise a health concern in these young age groups. The MOE values for the mean UB acute dietary exposure and for the 95th percentile UB raises a health concern for nickel-sensitised individuals. The MOE values for an acute scenario regarding consumption of a glass of water on an empty stomach do not raise a health concern.

A Search for Similar Patterns in Hair Trace Element and Mineral Content in Children with Down's Syndrome, Obesity, and Growth Delay

The objective of the present study was to perform comparative analysis of hair trace element and mineral levels in children with Down's syndrome, growth delay, and obesity in order to reveal common and specific patterns. Hair Zn (14, 7, and 15%), Ca (38%, 24%, and 47%), and Mg (33%, 31%, and 49%) levels in children with Down's syndrome, obesity, and growth delay were lower than the respective control values. At the same time, patients with Down's syndrome and growth delay were characterized by 27% and 21%, as well as 24% and 20% lower hair Co as well as Cu content than healthy examinees. Certain alterations were found to be disease-specific. Particularly, in Down's syndrome children, hair Cr, Fe, and V levels were significantly lower, whereas hair P content exceeded the control values. Obese children were characterized by significantly increased hair Cr content. At the same time, hair Mn and Si levels in children with growth delay were lower as compared with the controls. In regression models, all three studied diseases were considered as negative predictors of hair Cu content. Down's syndrome and growth delay, but not obesity, were inversely associated with hair Co content. Both Down's syndrome and obesity were inversely associated with hair Zn content. Based on the revealed similarities in altered hair element, content it is proposed that deficiency of essential elements may predispose Down's syndrome patients to certain syndrome comorbidities including growth delay and obesity, although further detailed studies are required.

Prenatal and postnatal cadmium exposure and cellular immune responses among pre-school children

BACKGROUND

Experimental studies have demonstrated that cadmium exposure induces alterations on immune function, but epidemiological evidence is lacking.

OBJECTIVE

To examine the associations between prenatal and postnatal cadmium exposure and cellular immune responses among pre-school children.

METHODS

Pre-school aged children (n = 407) were followed from a prospective birth cohort study in Wuhan, China. Maternal urinary and children's plasma cadmium concentrations were measured as biomarkers of prenatal and postnatal cadmium exposure, respectively. Children's cellular immune responses were assessed by peripheral blood T lymphocyte subsets and plasma cytokines. Multivariable adjusted models were applied to estimate the associations of prenatal and postnatal cadmium exposure with T lymphocyte subsets and cytokines, and the effect modification by child gender were also examined.

RESULTS

Maternal urinary cadmium was associated with reduced absolute counts of CD3⁺CD4⁺ cells (-12.45%; 95% CI: -23.74%, 0.40% for the highest vs. lowest quartile; p for trend = 0.045). Inverse associations of maternal urinary cadmium with %CD3⁺CD4⁺ cells and CD4⁺/CD8⁺ ratio were only observed among females (both p-interaction < 0.050); whereas an inverse association with absolute counts of CD3⁺CD8⁺ cells was only observed among males (p-interaction = 0.057). Positive associations of maternal urinary cadmium with %CD3⁺CD4⁺ cells, interleukin-4 (IL-4), and IL-6 were only observed among females, although there were no significant interactions. We observed no clear associations of children's plasma cadmium with T lymphocyte subsets and cytokines.

CONCLUSION

Prenatal but not postnatal cadmium exposure was associated with sex-specific alterations on children's cellular immune responses.

An On-Off-On Fluorescence Probe Based on Coumarin for Cu2+, Cysteine, and Histidine Detections

A simple coumarin-based Schiff base (probe L) was successfully developed. It showed strong green fluorescence emission at 527 nm with a 70.3% of fluorescence quantum efficiency (Φ_F). However, after the addition of common metal ions, probe L can only combine with Cu²⁺ ions and displayed significant fluorescence quenching of > 96.2% (Φ_F = 2.7%) due to the paramagnetic quenching action from Cu²⁺. Conversely, by the coordination action of cysteine (Cys) and histidine (His), the quenching fluorescence of the complex (L-Cu²⁺) between probe L and Cu²⁺ ions was recovered mostly because the Cys and His can usurp Cu²⁺ of L-Cu²⁺ and led to the liberation of probe L. Based on the fluorescence changes of probe L with the actions of Cu²⁺, Cys, and His, an on-off-on reversible fluorescence probe for sensitive and specific monitoring Cu²⁺, Cys, and His has been prepared. More importantly, the probe L and L-Cu²⁺ ensemble can be used, respectively, to test Cu²⁺ and Cys/His in live cells and human urine samples with great reliability.

Highly Selective Fluorescent Probe for the Detection of Copper (II) and Its Application in Live Cell Imaging

The development of fluorescent methods for the detection of metal ions is of great importance due to their diverse environmental and biological roles. Herein, a rhodamine 6G-based off-on fluorescent probe (L1) with a t-butyl pyrrole moiety as the recognition site was designed and synthesized. Photophysical studies show that L1 exhibits excellent sensitivity and selectivity towards Cu²⁺ to other metal ions in neutral acetonitrile aqueous media. Mechanism studies suggest that the recognition process may associate with a Cu²⁺ promoted hydrolysis reaction of L1. Furthermore, L1 has been successfully applied in fluorescence imaging of Cu²⁺ ion in living cells.

A novel jointly colorimetric and fluorescent sensor for Cu2+ recognition and its complex for sensing S2- by a Cu2+ displacement approach in aqueous media

In this work, a simple and easily synthesized Schiff-based derivative colorimetric and fluorescent sensor (1), 4-dimethylamino-benzoic acid (2-imidazole formaldehyde)-hydrazide, was obtained for the detection of Cu²⁺ and S^2-. The compound 1 exhibited dual spectral responses to Cu²⁺, that is, vivid color change and fluorescence enhancement in the presence of Cu²⁺. The detection limits were valued as 0.46 μM and 15 nM according to absorption and fluorescent response, respectively. Both of them are below the World Health Organization (WHO) guidelines for drinking water (31.5 μM). In addition, the ensemble (1-Cu²⁺) selectively and sensitively detected a low concentration of S^2-. As the addition of S^2- instantly removed Cu²⁺ from the ensemble (1-Cu²⁺) resulting in a color change from yellow to colorless and a "turn-off" fluorescent response. The detection limit for S^2- was estimated as 0.12 μM (from fluorescent method) and 0.68 μM (from absorption method), respectively, each of which was also lower than the maximum allowable level of S^2- (15 μM) in drinking water defined by the WHO. The binding process was confirmed via UV-vis absorption, fluorescence measurements, ¹H NMR, mass spectroscopy and density functional theory calculation. What's more, successful practical application of test paper is used to inspect the S^2- which means the convenient and rapid assay in real samples can be achieved.

Association of SNPs in transferrin and transferrin receptor genes with blood iron levels in human

Iron is bound to mobile transferrin (TF) and ferritin in blood. TF receptors (TFRC and TFR2) regulate intracellular iron by delivering iron from TF into the cytoplasm. In this study, we examined the effects of 10 single nucleotide polymorphisms (SNPs) in each of the genes for TF and TF receptors on blood iron concentrations in Japanese subjects. Blood iron levels were determined by microwave plasma-atomic emission spectrometry and the SNPs were analyzed by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Blood iron levels in males were significantly higher than those in females. Therefore, the analysis was performed only in males. Blood iron concentrations did not correlate with age and postmortem intervals in males. Among the 10 SNPs in TF, TFRC, and TFR2 genes, significant associations were observed between TF genotypes (rs12769) and male iron concentrations. Individuals with genotype GG in rs12769 had significantly higher blood iron concentrations than those with GA. Previous studies have shown the association between high tissue iron concentrations and disease, liver iron levels are higher in infants dying from sudden infant death syndrome and decreased blood iron concentrations were observed in critically ill children. Therefore, rs12769 in TF might be related to diseases and mortality risk.

Association of SNPs in genes encoding zinc transporters on blood zinc levels in humans

Zinc homeostasis in cells depends on zinc transporters, which are divided into 2 families: ZnT (SLC30A) and ZIP (SLC39A). In this study, we examined the effect of 20 single nucleotide polymorphisms (SNPs) in 10 genes encoding zinc transporters on blood zinc concentration in Japanese subjects (n = 102). Blood zinc levels were determined by microwave plasma-atomic emission spectrometry, and SNPs were analyzed by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Among the 20 SNPs examined, 3 SNPs (SLC30A3 rs11126936, SLC39A8 rs233804, and SLC39A14 rs4872479) were significantly associated with blood zinc concentration. Individuals with genotype TT and TG in rs11126936 showed significantly higher blood zinc concentrations than those with GG. As for rs233804, individuals harboring the A allele had significantly higher blood zinc concentrations than those without this allele. Furthermore, the genotype TT and TG in rs4872479 had significantly higher blood zinc concentrations than those with GG. Among these three SNPs, combination of SLC30A3 rs11126936 and SLC39A8 rs233804 may strongly affect blood zinc levels. This study is the first comprehensive investigation of the effect of SNPs in genes encoding zinc transporters on blood zinc concentration. Adverse effects of zinc deficiency are reported and above 3 SNPs may be related to genetic susceptibility to zinc deficiency.

Assessment the Exposure Level of Rare Earth Elements in Workers Producing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles

In order to assess occupational exposure level of 15 rare earth elements (REEs) and identify the associated influence, we used inductively coupled plasma mass spectrometry (ICP-MS) based on closed-vessel microwave-assisted wet digestion procedure to determinate the concentration of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in urinary samples obtained from workers producing ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggest that La and Ce were the primary component, together accounting for 97 % of total REEs in workers. The urinary levels of La, and Ce among the workers (6.36, 15.32 μg.g^-1 creatinine, respectively) were significantly enriched compared to those levels measured in the control subjects (1.52, 4.04 μg.g^-1 creatinine, respectively) (p < 0.05). This study simultaneously identified the associated individual factors, the results indicate that the concentrations in over 5 years group (11.64 ± 10.93 for La, 27.83 ± 24.38 for Ce) were significantly elevated compared to 1-5 years group (2.58 ± 1.51 for La, 6.87 ± 3.90 for Ce) (p < 0.05). Compared the urinary levels of La and Ce at the separation and packaging locations (9.10 ± 9.51 for La, 22.29 ± 21.01 for Ce) with the other locations (2.85 ± 0.98 for La, 6.37 ± 2.12 for Ce), the results show urinary concentrations were significantly higher in workers at separation and packaging locations (p < 0.01). Inter-individual variation in levels of La and Ce in urine is the result of multi-factorial comprehensive action. Further researches should focus on the multiple factors contributing to the REEs levels of the occupationally exposed workers.