Blood lead and mercury levels are associated with low resting heart rate in community adolescent boys

Functionalization of Ti3C2 MXene with Diethylenetriamine for a Column-Based Solid-Phase Extraction of Heavy Metals

Transition metal carbides, nitrides, and carbonitrides, known as MXenes, are attracting attention for their potential application in trace detection of heavy metals. This study presents diethylenetriamine-functionalized Ti3C2 MXene for trace detection of cadmium and lead ions. Functionalization of Ti3C2 significantly improves the adsorption properties of MXenes by replacing native functional groups with silane moieties that contain three amine groups, offering higher affinity for heavy metals. We demonstrate the efficacy of this material as a solid-phase extractor in column-based solid-phase extraction for heavy metal analysis in various food samples. Diethylenetriamine-functionalized Ti3C2 coupled with the flame atomic absorption spectrometer exhibits exceptional analytical performance. While maintaining a robust stability for 15 adsorption-desorption cycles, the proposed method shows detection limits of 0.09 ng mL-1 for cadmium and 1.7 ng mL-1 for lead, with a linear dynamic range of 0.3-50 ng mL-1 for cadmium and 5-90 ng mL-1 for lead, and relative recoveries of 97.50-101.05 and 98.65-100.80% for cadmium and lead ions, respectively. Additionally, relative standard deviations and enrichment factors were calculated as 0.60-4.70% and 42.3 for cadmium ions and 0.65-1.24% and 44.2 for lead ions.

Biomonitoring of Mercury and Lead Levels in the Blood of Children Living near a Tropical River Impacted by Artisanal and Small-Scale Gold Mining in Colombia

(1) Background: Mercury and lead contamination resulting from various anthropogenic activities represents a global environmental problem and a considerable risk to the health of the human population. (2) Methods: The objective of this research was to evaluate the concentrations of mercury (Hg) and Lead (Pb) in the blood of the child population in the municipalities in the Atrato River basin using a direct Hg analyzer and graphite furnace atomic absorption spectrometry. (3) Results: In total, 171 children (5-14 years of age) were taken into account, and 18.71% (32) of the children had concentrations of Hg and Pb above the permissible values established by the WHO. In the municipality of UN, 19 children had blood Hg concentrations between 5.29 and 17.71 μg/L. In CA, two children had concentrations of 5.03 and 8.43 μg/L, separately. In the case of Pb, seven children showed concentrations between 3.60 and 4.83 μg/dL in the municipality of RQ, three in UN (3.59, 3.61, and 4.60 μg/dL), and one in Carmen de Atrato (5.47 μg/dL). (4) Conclusions: The levels of Hg and Pb in the blood of children living in the riparian areas of the Atrato River basin are related to gold mining activities in the basin and the consumption of contaminated fish.

Effects of Blood Lead Levels <10 µg/dL in School-Age Children and Adolescents: A Scoping Review

CONTEXT

Lead exposures among school-age children are a major public health issue. Although the harmful effects of lead exposure during the first years of life are well known, there is not as much understanding of the effects of low levels of lead exposure during later childhood.

OBJECTIVES

To review the effects of blood lead levels (BLLs) <10 µg/dL in school-age children and adolescents.

DATA SOURCES

We searched Medline, Embase, Global health, CINAHL, Scopus, and Environmental Science Collection databases between January 1, 2000, and May 11, 2023.

STUDY SELECTION

We included peer-reviewed English-language articles that presented data on the effects of BLLs <10 µg/dL in individuals ages 5 through 18 years.

DATA EXTRACTION

Data on country, population, analytic design, sample size, age, BLLs, outcomes, covariates, and results were extracted.

RESULTS

Overall, 115 of 3180 screened articles met the inclusion criteria. The reported mean or median BLL was <5 µg/dL in 98 articles (85%). Of the included articles, 89 (77%) presented some evidence of an association between BLLs <10 µg/dL during school age and detrimental outcomes in a wide range of categories. The strongest evidence of an association was for the outcomes of intelligence quotient and attention-deficit/hyperactivity disorder diagnoses or behaviors.

LIMITATIONS

Few articles controlled for BLLs at age <5 years, limiting conclusions about the relation between later BLLs and outcomes.

CONCLUSIONS

BLLs <10 µg/dL in school-age children and adolescents may be associated with negative outcomes. This review highlights areas that could benefit from additional investigation.

Association of low-level lead exposure with all-cause and cardiovascular disease mortality in US adults with hypertension: evidence from the National Health and Nutrition Examination Survey 2003-2010

BACKGROUND

To explore the association of low-level lead exposure with all-cause mortality and cardiovascular disease (CVD) mortality among hypertensive patients.

METHODS

This cohort study enrolled 6453 adults with hypertension from the National Health and Nutrition Examination Survey 2003-2010 and followed mortality information through December 31, 2019. The baseline population were divided into four groups based on quartiles of blood lead levels (Q1: < 1.2 μg/dL, Q2: 1.2-1.6 μg/dL, Q3: 1.7-2.4 μg/dL, Q4: 2.5-4.9 μg/dL). The correlation of blood lead levels to mortality was investigated by Kaplan-Meier survival curves, restricted cubic spline (RCS), proportional hazard regression model, and subgroup analysis.

RESULTS

During a median follow-up period of 136 (interquartile range 113, 164) months, a total of 1943 (30.1%) deaths were documented, among which 553 (28.5%) were due to CVD. Blood lead showed a linear dose-response relationship with all-cause and CVD mortality. After adequate adjusting for confounders, the risk of all-cause death rose by 23% for each unit increase in continuous variable blood lead (hazard ratio (HR): 1.23; 95% confidence interval (CI):1.16-1.30). When blood lead was a quartile group variable, participants in the Q 4 group had a 73% higher risk of death than those in the Q 1 group (HR:1.73; 95% CI: 1.43-2.10; P for trend < 0.001). The association for CVD mortality was analogous. The concordant results were achieved in the subgroup analysis.

CONCLUSION

Elevated blood lead levels were strongly associated with an increased all-cause and CVD mortality in adults with hypertension, even at the reference range of blood lead.

Determinants affecting the blood mercury levels of preschool children in Shanghai, China: A cross-sectional study

Infants and children are vulnerable to mercury (Hg)-induced toxicity, which has detrimental effects on their neurological development. This study measured blood Hg levels (BMLs) and identified potential factors influencing BMLs, including demographic and socioeconomic factors, lifestyle, and daily dietary habits, among 0 to 7-year-old children in Shanghai. Our study recruited 1474 participants, comprising 784 boys and 690 girls. Basic demographic and lifestyle information were obtained and blood Hg were analyzed using the Direct Mercury Analyzer 80. The blood Hg concentrations of children in Shanghai ranged from 0.01 to 17.20 μg/L, with a median concentration of 1.34 μg/L. Older age, higher familial socioeconomic status, higher residential floors, and a higher frequency of consuming aquatic products, rice, vegetables, and formula milk were identified as risk factors. Other potential influencing factors including the mother's reproductive history (gravidity and parity), smoking (passive smoking), supplementation of fish oil and calcium need to be further investigated. These findings can be useful in establishing appropriate interventions to prevent children's high blood Hg concentrations in Shanghai and other similar metropolitan cities.

Childhood lead exposure and sex-based neurobehavioral functioning in adolescence

It is well documented that childhood lead exposure is associated with long-term decreases in intelligence quotients (IQ). Lesser known is the relationship with neurobehavioral domains, especially in adolescence. This study sought to identify cross-sectional and longitudinal associations between lead exposure and adolescent executive and visual-motor functioning and examine sex-based differences. Participants were 681 children from Jintan, China who had their blood lead levels (BLLs) assessed at age 3-5 years and 12 years old and neurobehavioral functioning assessed through the University of Pennsylvania Computerized Neurocognitive Battery (PennCNB) platform http://www.med.upenn.edu/bbl at 12 years old. Mean BLLs were 6.41 mcg/dl at age 3-5 years and 3.10 mcg/dl at 12. BLLs at 3-5 years and 12 years were used as predictors for the individual neurobehavioral domains in general linear models while controlling for father and mother occupation and education, residence location, age, and adolescent IQ. Models were run separately for males and females. In adjusted models, males BLLs at 3-5 years were associated with increased time to correctly complete tasks in multiple domains including abstraction/flexibility (β = 19.90, 95% CI( 4.26, 35.54) and spatial processing (β = 96.00, 95% CI 6.18, 185.82) at 12 years. For females in adjusted models, BLLs at 3-5 years were associated with increasing time to correctly complete tasks on the episodic memory domain task (β = 34.59, 95% CI 5.33, 63.84) at 12 years. Two adolescent cross-sectional relationships remained in the adjusted models for males only, suggesting a positive association between BLLs and increasing time for correct responses on the attentional domain task (β = 15.08, 95% CI 0.65, 29.51) and decreasing time for correct responses on the episodic memory task (β = -73.49, 95% CI -138.91, -8.06) in males at 12 years. These associations remained with and without controlling for IQ. These results suggest that lead exposure is associated with overall deficits in male and female neurobehavioral functioning, though in different domains and different timing of exposure.

Bifunctional Amine- and Thiol-Modified Ti3C2Tx MXene for Trace Detection of Heavy Metals

Surface functionalization of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, also known as MXenes, is a powerful approach for modification of their physical and chemical properties for new applications. In this study, we demonstrate the synthesis of a bifunctional Ti₃C₂T_x MXene modified with amine and thiol groups through a facile condensation reaction. We successfully employed the resulting NH₂/SH-Ti₃C₂T_x MXene as a solid phase in the ultrasonic-assisted dispersive micro solid-phase extraction (d-μ-SPE) method for the analytical determination of heavy metals at trace levels in food and soil samples. The prepared NH₂/SH-Ti₃C₂T_x MXene showed remarkable performance in the ultrasonic-assisted d-μ-SPE method with limits of detection of 0.12 and 2.30 ng mL^-1, with linear dynamic ranges of 0.50-90 μg L^-1 and 10-120 μg L^-1 for cadmium (Cd²⁺) and lead (Pb²⁺) ions, respectively. Furthermore, the extraction efficiencies were greater than 97%, with a relative standard deviation of less than 3% for five separate batch experiments in the determination of 5.0 μg L^-1 of Cd²⁺ and Pb²⁺. This study shows that NH₂/SH-Ti₃C₂T_x can be used as a simple, rapid, reliable, selective, and sensitive material in the d-μ-SPE method for the trace determination of Cd²⁺ and Pb²⁺ in soil and agricultural products. This study demonstrates the utility of MXenes for analytical chemistry and suggests that further advances in methods for the functionalization of MXenes can open new applications for these already exciting materials.

Longitudinal association of early childhood lead exposure and adolescent heart rate variability: influence of parental education

Lead exposure has been shown to dysregulate physiological stress responses. However, few studies have investigated the effect of lead exposure on later heart rate variability (HRV), an indicator of a stress response, in large samples of children. Furthermore, the interaction between social environmental factors and lead exposure in childhood, which commonly co-occur, remains understudied. This study examined relationships between childhood lead exposure and early adolescent physiological stress responses at different levels of parental education. Participants were 406 children from Jintan, China. Blood lead levels (BLLs) and parental education data were collected at 3-5 years of age, and HRV outcomes assessed at 12 years via frequency domain measures (LF/HF ratio) collected during an induced stress test. Results show a significant interaction between parental education and BLLs at 3-5 years. This relationship was found to be most consistent for the interaction between BLLs and mother's years of education for both the planning (β = 0.12, p = 0.046) and speaking (β = 0.11, p = 0.043) phase of the stress task, suggesting that increasing years of mother's education may enhance the deleterious influence of lead exposure on the HRV frequency measure, LF/HF ratio. This research highlights the complexity in lead exposure induced outcomes.

Early childhood lead exposure and adolescent heart rate variability: A longitudinal cohort study

Lead is a known neurotoxicant with many detrimental health effects, including neurocognitive deficits and cardiovascular and metabolic disorders. However, few studies have tested the association between lead exposure and the physiological stress response, which in and of itself may act as a precursor to and/or underlying mechanism of detrimental health outcomes. The purpose of this study was to examine the influence of early childhood and early adolescent low-level lead exposure on early adolescent heart rate variability, a widely-used measure of physiological stress. Participants were 408 children from Jintan, China for whom blood lead levels were measured between 3 and 5 years (early childhood) and again at 12 years (early adolescence). Heart rate variability was assessed at 12 years while participants underwent an induced stress task utilizing the ratio of low to high frequency (LF/HF) ECG measures. Mean blood lead levels in the cohort were 6.63 mcg/dl and 3.10 mcg/dl at 3-5 years and 12 years, respectively. Blood lead levels at 3-5 years of age (β 0.06, p = 0.027), but not at age 12 (β -0.05, p = 0.465), were significantly associated with LF/HF measures while controlling for multiple sociodemographic variables, potentially reflecting a dysregulated stress response with a shift towards sympathetic dominance. These findings suggest that early childhood lead exposure may have a detrimental influence on early adolescent autonomic responses to acute stress, which holds implications for cardiovascular health and overall growth and development.

Functional consequences of lead and mercury exposomes in the heart

Lead and mercury are heavy metals that are highly toxic to life forms. There are no known physiological processes that require them, and they do not have a particular threshold concentration to produce biologic damage. They are non-biodegradable, and they slowly accumulate in the environment in a dynamic equilibrium between air, water, soil, food, and living organisms. Their accumulation in the environment has been increasing over time, because they were not banned from use in anthropogenic industrial production. In their +2 cationic state they are powerful oxidizing agents with the ability to interfere significantly with processes that require specific divalent cations. Acute or chronic exposure to lead and mercury can produce multisystemic damage, especially in the developing nervous systems of children and fetuses, resulting in variety of neurological consequences. They can also affect the cardiovascular system and especially the heart, either directly through their action on cardiomyocytes or indirectly through their effects on innervation, humoral responses or blood vessel alterations. For example, heart function modified by these heavy metals are heart rate, contraction, excitability, and rhythm. Some cardiac molecular targets have been identified and characterized. The direct mechanisms of damage of these heavy metals on heart function are discussed. We conclude that exposome to these heavy metals, should be considered as a major relevant risk factor for cardiac diseases.

Prenatal methylmercury exposure is associated with decrease heart rate variability in children

BACKGROUND

Although several epidemiological studies have suggested mercury (Hg) might be associated with cardiotoxicity, the impact of Hg exposure on cardiac autonomic activity and blood pressure in children has not been investigated at Hg exposure levels equivalent to the Environmental Protection Agency (EPA) reference dose.

OBJECTIVE

To investigate the association between low dose prenatal and recent methylmercury (MeHg) exposures and cardiac autonomic function and blood pressure with adjustment for factors such as fish consumption among children from a high fish consumption coastal city.

METHODS

Children aged 7-8 years were recruited from the birth cohort of our previous study. Heart rate variability (HRV), resting heart rate (RHR) and blood pressure were measured as surrogate markers of cardiac autonomic function. Cord blood and current whole blood Hg concentration were used as biomarkers of prenatal and recent MeHg exposure, respectively. Recent fish consumption information was estimated with a food frequency questionnaire.

RESULTS

Among 604 children, median cord blood and whole blood Hg concentrations were 45.9 nmol/L (IQR: 32.8-65.03 nmol/L) and 13.57 nmol/L (IQR: 9.29-19.72 nmol/L), respectively. Our results demonstrated that prenatal MeHg exposure was associated with decreased HRV (i.e. low CVRR, SDRR, and RMSSD), reflecting reduced parasympathetic activity (i.e. low CCV_HF and HF), and a sympathovagal balance shift toward sympathetic predominance (i.e. high %LF and LF/HF ratio). Adjustment of recent fish consumption further increased the significance and magnitude of the adverse associations of MeHg.

CONCLUSION

The results of this study suggest that prenatal MeHg exposure is associated with decreased parasympathetic modulation of cardiac autonomic function in children.