Contemporary blood lead levels of children aged 0-84 months in China: A national cross-sectional study

Blood Lead Levels in the Population Living in Algeria: A Cross-Sectional National Study

Lead poisoning, is currently recognized as a real public health problem, The WHO classifies lead as one of 10 chemicals of serious public health concern. In Algeria and North Africa, to date, no study on the evaluation of lead impregnation has been carried out at the national level. The main objective of this work is to assess the exposure of the general Algerian population to lead. A cross-sectional study was carried out over the entire Algerian national territory, on a population aged between 3 and 74 years old. The survey lasted three years, A questionnaire, a clinical examination and a blood sample were carried out for each individual. Generalized linear regression models were used to determine the factors influencing lead levels measured in blood samples. The study population, spread over 39 wilayas and 121 districts, consists of 3674 individuals. The mean lead levels were 28.27 μg/L, the median was 22.22 μg/L, and the 95th percentile was 73.83 μg/L, Blood lead levels were influenced differently by age, gender, wilaya of residence, dietary habits such as consumption of canned food and the way in which water is conserved for daily consumption. The use of kohl has been confirmed as a potential source of lead exposure. In Algeria, a blood lead value of 75 µg/L serves as the Reference Exposure Value, guiding public health responses and risk management strategies, Recommendations have been issued to reduce the blood lead levels of the general population in Algeria in terms of limitation of lead in the sources of exposure, installation of an effective health monitoring system.

Environmental exposure and child health in China

Chinese children are exposed to broad environmental risks ranging from well-known hazards, such as pesticides and heavy metals, to emerging threats including many new man-made chemicals. Although anecdotal evidence suggests that the exposure levels in Chinese children are substantially higher than those of children in developed countries, a systematic assessment is lacking. Further, while these exposures have been linked to a variety of childhood diseases, such as respiratory, endocrine, neurological, behavioral, and malignant disorders, the magnitude of the associations is often unclear. This review provides a current epidemiologic overview of commonly reported environmental contaminants and their potential impact on children's health in China. We found that despite a large volume of studies on various topics, there is a need for more high-quality research and better-coordinated regional and national data collection. Moreover, prevention of such diseases will depend not only on training of environmental health professionals and enhanced research programs, but also on public education, legislation, and networking.

Lead exposure in Chinese children: Urbanization lowers children's blood lead levels (BLLs)

Lead is a toxic metal that can pose a huge threat to children's health. China has experienced rapid urbanization since the reform in 1978; however, there has been no examination of the potential influence of this urbanization on children's blood lead levels (BLLs). This study is the initial investigation to explore the correlation between urbanization and BLLs in Chinese children. Five windows of time are considered: pre-2000, 2001-2005, 2006-2010, 2011-2015 and 2016-2021. The results show that urbanization affected lead distribution in urban soil and agricultural soil during the above periods, especially in northern China. The higher non-carcinogenic risk of lead for children is consistent with the lead pollution in soil (3 < Igeo ≤ 4). Urban children's BLLs are slightly higher than those of rural children in 2001-2010, but rural children's BLLs in 2011-2021 are higher than those of urban children during China's urbanization. The areas of rural decline and the areas of urban growth increased across all the window periods. However, the BLLs decrease in all rural and urban areas during all window periods, especially in urban areas. Children's BLLs have a significantly negative correlation with urban areas (p < 0.01). Therefore, China's urbanization has a significant effect on the decrease in children's BLLs. The significance of this study is to provide a fresh perspective and innovative strategy for policymaking in order to reduce children's BLLs and prevent lead exposure. This can be achieved by transforming their external living environment from a rural lifestyle to an urban one, while also ensuring access to well education and maintaining a balanced nutrient intake.

Distribution of blood lead and cadmium levels in healthy children aged 0 to 18 years and analysis of related influencing factors in Henan, China: data findings from 2017 to 2022

BACKGROUND

There is still a lack of data on blood lead levels (BLLs) and blood lead levels (BLLs) in healthy children of all ages from 0 to 18 years in China. This study was performed to analyze the BLLs and BCLs in healthy children aged 0-18 years from 2017 to 2022 in urban and rural areas of Henan Province, Central China, as well as their relationships with socio-demographic variables and certain relevant exposure factors. To provide a basis for evaluating public health policy development and exposure risk management.

METHODS

This was an observational study containing data from 17 prefecture-level cities in Henan, China. Blood Pb and Cd levels were determined using a triple quadrupole inductively coupled plasma mass spectrometer equipped with an autosampler. We first calculated the concentrations of Pb and Cd elements in participants of different genders, ages and years, and then created visual graphs depicting the distribution of each element in terms of gender, age and year (2017-2022). The rates between different groups were compared using the Chi-square test or Fisher exact test (if applicable). The means were compared by one-way ANOVA, medians were compared with the Kruskal-Wallis rank-sum test. Generalized linear models (GLM) were performed to estimate the effects of various factors on blood Pb and Cd concentrations in children.

RESULTS

We recruited a total of 25,920 children (16,142 boys and 9,778 girls) aged 0.01 to 18.00 years (2.58 (1.00,6.25)). The median of BLLs was 23.48µg/L, around 9.39% of studied children had elevated BLLs. The median of BCLs was 0.66µg/L, around 1.84% of studied children had elevated BCLs. The median blood Pb concentration was higher in boys (23.90µg/L) than in girls (22.75µg/L) (P<0.001). The median blood Pb concentration was highest in the 3-7 years group (24.51µg/L) and the median blood Cd concentration was highest in the 1-3 years group (0.66µg/L) among all age groups. Both BLLs and BCLs were substantially higher in children in 2020-2022 compared to 2017-2019. Rural children had lower BLLs and higher BCLs. The results of the generalized linear model showed that children in households using Oil, coal, pellet or other wood as a fuel for heating, children with higher frequency of exposure to tobacco smoke and beverage intake had significantly increased chances of elevated BLLs and BCLs.

CONCLUSIONS

Pb and Cd exposure of children in this area is relatively low, but associated risk factors continue to exist in vulnerable populations. This study is the first big data analysis of Pb and Cd in children in Henan, China, and provides baseline information for future research.

Quantitative relationships of FAM50B and PTCHD3 methylation with reduced intelligence quotients in school aged children exposed to lead: Evidence from epidemiological and in vitro studies

At present, the application of DNA methylation (DNAm) biomarkers in environmental health risk assessment (EHRA) is more challenging due to the unclearly quantitative relationship between them. We aimed to explore the role of FAM50B and PTCHD3 at the level of signaling pathways, and establish the quantitative relationship between them and children's intelligence quotients (IQs). DNAm of target regions was measured in multiple cell models and was compared with the human population data. Then the dose-response relationships of lead exposure with neurotoxicity and DNAm were established by benchmark dose (BMD) model, followed by potential signaling pathway screening. Results showed that there was a quantitative linear relationship between children's IQs and FAM50B/PTCHD3 DNAm (DNAm between 51.40 % - 78.78 % and 31.41 % - 74.19 % for FAM50B and PTCHD3, respectively), and this relationship was more significant when children's IQs > 90. The receiver operating characteristic (ROC) and calibration curves showed that FAM50B/PTCHD3 DNAm had a satisfying accuracy and consistency in predicting children's IQs, which was confirmed by sensitivity analysis of gender and CpG site grouping data. In cell experiments, there was also a quantitative linear relationship between FAM50B DNAm and reactive oxygen species (ROS) production, which was mediated by PI3K-AKT signaling pathway. In addition, the lead BMD of ROS was close to that of FAM50B DNAm, suggesting that FAM50B DNAm was a suitable biomarker for the risk assessments of adverse outcomes induced by lead. Taken collectively, these results suggest that FAM50B/PTCHD3 can be applied to EHRA and the prevention/intervention of adverse effects of lead on children's IQs.

Clinical case analysis of 32 children aged 0-6 years with lead poisoning in Nanning, China

Lead is one of the heavy metals that is toxic and widely distributed in the environment, and children are more sensitive to the toxic effects of lead because the blood-brain barrier and immune system are not yet well developed. The objective of the study was to investigate the clinical characteristics of lead poisoning in children aged 0∼6 years in a hospital in Guangxi, and to provide scientific basis for the prevention and treatment of lead poisoning. We collected and analyzed the clinical data of 32 children with lead poisoning admitted to a hospital in Guangxi from 2010 to 2018. The results showed that most of the 32 cases presented with hyperactivity, irritability, poor appetite, abdominal pain, diarrhea, or constipation. The hemoglobin (HGB), mean corpusular volume (MCV), mean corpuscular hemoglobin (MCH), and hematocrit (HCT) of the lead-poisoned children were all decreased to different degrees and were below normal acceptable levels. Urinary β2-microglobulin was increased. Blood lead levels (BLL) decreased significantly after intravenous injection of the lead chelator, calcium disodium edetate (CaNa2-EDTA). In addition, HGB returned to normal levels, while MCV, MCH, and HCT increased but remained below normal levels. Urinary β2-microglobulin was reduced to normal levels. Therefore, in this cohort of children, the high-risk factors for lead poisoning are mainly Chinese medicines, such as baby powder. In conclusion, lead poisoning caused neurological damage and behavioral changes in children and decreased erythrocyte parameters, leading to digestive symptoms and renal impairment, which can be attenuated by CaNa2-EDTA treatment.

Metabolomics insights into the effects of pre-pregnancy lead exposure on bone metabolism in pregnant rats

Today's women of childbearing age with a history of high lead (Pb) exposure in childhood have large Pb body burdens, which increases Pb release during pregnancy by promoting bone Pb mobilisation. The purpose of this study was to investigate the metabolic mechanisms underlying bone Pb mobilisation and explore the bone metabolism-related pathways during pregnancy. Drinking water containing 0.05% sodium acetate or Pb acetate was provided to weaned female rats for 4 weeks followed by a 4-week washout period, and then rats were co-caged with healthy males of the same age until pregnancy. Blood and bone tissues of the female rats were collected at gestational day (GD) 3 (early pregnancy), GD 10 (middle pregnancy), and GD 17 (late pregnancy), respectively. Pb and calcium concentrations, biomarkers for bone turnover, bone microstructure, serum metabolomics, and metabolic indicators were intensively analyzed. The results demonstrated that pre-pregnancy Pb exposure elevated blood lead levels (BLLs) at GD17, accompanied by a negative correlation between BLLs and trabecular bone Pb levels. Meanwhile, Pb-exposed rats had low bone mass and aberrant bone architecture with a larger number of mature osteoclasts (OCs) compared to the control group. Moreover, the metabolomics uncovered that Pb exposure caused mitochondrial dysfunction, such as enhanced oxidative stress and inflammatory response, and suppressed energy metabolism. Additionally, the levels of ROS, MDA, IL-1β, and IL-18 involved in redox and inflammatory pathways of bone tissues were significantly increased in the Pb-exposed group, while antioxidant SOD and energy metabolism-related indicators including ATP levels, Na+-K+-ATPase, and Ca2+-Mg2+-ATPase activities were significantly decreased. In conclusion, pre-pregnancy Pb exposure promotes bone Pb mobilisation and affects bone microstructure in the third trimester of pregnancy, which may be attributed to OC activation and mitochondrial dysfunction.

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.

Lead pollution-related health of children in China: Disparity, challenge, and policy

Lead (Pb) is a neurotoxic metal, and no level of lead exposure is safe for children. China has still experienced problems on child lead poisoning even though the Chinese government has phased out leaded gasoline since 2000. The underlying problem affecting the lead pollution-related health of children in China remains to be comprehensively investigated. It is found that although the significant decline of BLLs, as the Geometric Mean (GM), from 91.40 μg/L^GM in 2001 to 37.52 μg/L^GM in 2018 is observed, the average BLLs of children are still above 50 μg/L or more [average 59.70 (60.50-65.02, 95 % CI) μg/L^GM] after phasing out leaded gasoline since 2000 in China. Lead exposure causes 29.67 MID per 1000 children with a loss of 98.23 (59.40-146.21, 95 % CI) DALYs per 1000 in China, which is greater than the levels reported from the Western Pacific Region and other low- and middle-income countries. A significant correlation is observed between the number of child crimes (NoCCs) and the outcomes of long-term lead exposure for children in China. Although the disparities in BLLs in China are strongly influenced by unequal distributions of potential multi-lead related sources (soil lead, PM2.5 lead, dust lead), unbalance development of local industrialization and economies, as well as incorrect health care for younger children, the notable emissions from coal combustion (CC) and non-ferrous metals (NMS) exploitation dominate the crucial sources of low-level lead exposure to children after phasing out leaded gasoline in China currently. Faced with the unequal and disparate distribution of BLLs in China, the big bottleneck is to decrease the BLLs exertions of 36-45 μg/L in the next few decades. The Chinese government needs to make more efforts on developing more strict guidelines, implementing more policy strategies on prevention and management of blood Pb poisoning, and monitoring the nationwide changes in children's BLLs continuously.

Effect of lead, calcium, iron, zinc, copper and magnesium on anemia in children with BLLs ≥ 100 μg/L

OBJECTIVE

Adverse effects of lead exposure on children's health have been demonstrated. While studies have examined the relationship between iron status and low-level lead exposure in children with blood lead levels (BLLs) < 100 μg/L, few have investigated the association between blood lead and other trace elements and anemia in children with BLLs ≥ 100 μg/L. This study aimed to assess the levels of lead, iron, copper, zinc, magnesium, and calcium in children aged 0-14 with BLLs≥ 100 μg/L between 2009 and 2021, and to examine the relationship between blood lead, trace elements and anemia.

METHODS

A total of 11,541 children with BLLs ≥ 100 μg/L were included in this study. Venous blood samples were collected to measure blood lead levels, hemoglobin levels, and trace element levels. According to the World Health Organization standard, outpatients with hemoglobin levels < 110 g / L were defined as having anemia.

RESULTS

The study results found that high BLLs and blood calcium had a negative influence on Hb with odds ratios (95% confidence interval) of 1.411(1.208, 1.649) and 1.219(1.043, 1.424). High blood iron had a positive influence on Hb with odds ratios of 0.421(0.355, 0.499).

CONCLUSION

The results suggest that the risk of anemia rose significantly with higher BLLs, blood copper, and blood calcium levels, and decreases considerably with higher blood iron levels.

Evaluation of blood lead measurements by the 6-year external quality assessment program in China

BACKGROUND

Blood lead is an important clinical indicator. A typical tool for promoting standardisation or harmonisation is external quality assessment (EQA). Therefore, the National Centre for Clinical Laboratories (NCCL) in China launched the EQA Program for blood lead measurement in 2006 to assess its standardisation process.

METHODS

Blood lead EQA samples tested for homogeneity and stability were sent to participating laboratories. The return data were grouped according to the detection method. The robust mean value, robust coefficient of variation (CV) and standard uncertainty were calculated according to ISO 13528. The evaluation criteria were determined based on a thorough analysis of the previous pass rate and the current detection level. Overall trends in the blood lead EQA program over 6 years were investigated by calculating the pass rates of participating laboratories. We compared the pass rates and current issues of different detection methods and analysed the target values, bias and CV results of mainstream detection methods.

RESULTS

A total of 4,283 laboratories participated in EQA programs from 2017 to 2022. The pass rates were generally increasing while the inter-laboratory mean CVs were decreasing. For samples with varying concentrations, the higher the concentration, the smaller the CV. According to the evaluation criteria, the most used measurement methods, Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Tungsten Ship Atomic Absorption Spectrometry (TSAAS) demonstrated better performances than Differential Potentiometric Stripping (DPS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Flame Atomic Absorption Spectrometry (FAAS). Furthermore, DPS, ICP-MS and FAAS outperformed Anodic Stripping Voltammetry (ASV).

CONCLUSION

Our study provides reliable information on the standardisation of blood lead measurement procedures for manufacturers and clinical laboratories. Further improvements for standardisation are still required to make laboratories more patient-centred.

Domestic dogs as sentinels of children lead exposure: Multi-pathway identification and source apportionment based on isotope technique

Environmental lead exposure poses risks to children' health, thus exposure sources and pathways identification remain important concern and research scope. Due to sharing the same environment, domestic animals, especially dogs, have been used as useful sentinels to identify human lead exposure. However, more evidence is needed on whether domestic dogs could be used to identify the lead exposure pathways and sources of children. Thus, this study investigated the dietary habits, behaviors, and household environment of children and dogs in a typical coal-fired area in China. The lead levels and lead isotope ratios (Acronym: LIRs, expressed as ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶Pb) in dogs' and children's blood, as well as in environmental media (food, PM_2.5, indoor/outdoor dust, drinking water and soil) were measured to explore the predominant lead pollution sources and exposure pathways of children. The results showed that the LIRs of children's blood (²⁰⁸Pb/²⁰⁶Pb = 2.0703 ± 0.0076, ²⁰⁷Pb/²⁰⁶Pb = 0.8501 ± 0.0052) were similar to those of dogs' blood (²⁰⁸Pb/²⁰⁶Pb = 2.0696 ± 0.0085, ²⁰⁷Pb/²⁰⁶Pb = 0.8499 ± 0.0052), as well as similar to the LIRs of environmental media, i.e. children's food (²⁰⁸Pb/²⁰⁶Pb = 2.0731 ± 0.0057, ²⁰⁷Pb/²⁰⁶Pb = 0.8491 ± 0.0036) and coal (²⁰⁸Pb/²⁰⁶Pb = 2.0683 ± 0.017, ²⁰⁷Pb/²⁰⁶Pb = 0.8515 ± 0.01). Children and dogs had similar lead exposure pathways, but the contributions of each exposure pathway were different, i.e., 83.1% vs. 76.9% for children and dogs via food ingestion, 1.4% vs. 5.6% via particulate matter exposure, and 15.5% vs. 17.5% via household dust exposure, respectively. The contribution of food via ingestion to lead exposure remains dominant, and coal combustion is a main lead exposure source for children and domestic dogs.

Low level lead exposure in early childhood and parental education on adolescent IQ and working memory: a cohort study

BACKGROUND

The independent effect of lead exposure and parental education on children's neurocognition is well-documented. However, few studies have examined the combined effect of childhood lead exposure and parental education on adolescent neurocognition, especially in China.

OBJECTIVE

Examine both the combined and interactive effect of childhood blood lead levels (BLLs) and parental education on early adolescent neurocognition.

METHODS

417 children from a longitudinal cohort study in Jintan, China had BLLs measured at 3-5 years and 12 years, parental education levels assessed at 3-5 years, and neurocognitive outcomes tested at 12 years.

RESULTS

BLLs at 3-5 years were inversely associated with adolescent IQ (β -0.55 95% CI: -0.97, -0.13) but not working memory (β -0.06 95% CI: -0.23, 0.11) and parental education was positively associated with adolescent IQ (β 0.68 95% CI: 0.19, 1.17) and working memory (β 0.24 95% CI: 0.04, 0.44). BLLs and parental education evidenced combined effects on neurocognition, where children with higher BLLs and lower fathers' education had mean IQ scores 7.84 (95% CI: -13.15, -2.53) points lower than children with lower BLLs and higher fathers' education. There were significant associations between parental education and working memory, however, not with BLLs. The interaction between mother and father high school education and BLLs was insignificant for effects on IQ and working memory.

SIGNIFICANCE

Childhood lead exposure and parental education levels have a combined and long-term impact on IQ, evidence that may partially explain disparities in lead exposure associated outcomes and highlight those children at greatest risk for neurocognitive deficits.

IMPACT STATEMENT

Children continue to be exposed to low-levels of environmental lead in China and globally, warranting examination of the impact of such exposures. This paper demonstrates that even relatively low-level lead exposure in early childhood significantly influences adolescent neurocognitive functioning. Furthermore, co-existing social determinant of health-related variables, measured here as parental education, have a combined impact on neurocognition. These results highlight children at greater risk for neurocognitive deficits and demonstrate the need to examine the influence of lead exposure within the broader socio- ecological environment, as these factors work in tandem to influence longer-term neurocognitive outcomes.

Trace Metal(loid) Migration from Road Dust to Local Vegetables and Tree Tissues and the Bioaccessibility-Based Health Risk: Impacts of Vehicle Operation-Associated Emissions

Traffic activities release large amounts of trace metal(loid)s in urban environments. However, the impact of vehicle operation-associated emissions on trace metal(loid) enrichment in road dust and the potential migration of these trace metal(loid)s to the surrounding environment remain unclear. We evaluated the contamination, sequential fraction, and bioaccessibility of trace metal(loid)s in urban environments by assessing their presence in road dust, garden vegetables, and tree tissues, including bark and aerial roots, at a traffic-training venue impacted by vehicle operation emissions and, finally, calculated the bioaccessibility-based health risk. The results indicated a significant accumulation of trace metal(loid)s in road dust, with the highest lead (Pb), cadmium (Cd), and antimony (Sb) concentrations in the garage entrance area due to higher vehicle volumes, frequent vehicle starts and stops, and lower speeds. Aerial roots exposed to hill start conditions exhibited the highest Pb, Zn, and Sb levels, potentially caused by high road dust resuspension, confirming that this tree tissue is an appropriate bioindicator. Sequential extraction revealed high percentages of carbonate-, Fe/Mn oxide-, and organic/sulphide-associated fractions of Pb, copper (Cu), and zinc (Zn) in road dust, while most Cd, Cr, Ni, and Sb occurred as residual fractions. According to the potential mobilizable fractions in sequential extraction, the in vitro gastrointestinal method could be more suitable than the physiologically based extraction test to evaluate the bioaccessibility-related risk of traffic-impacted road dust. The bioaccessibility-based health risk assessment of the road dust or soil confirmed no concern about noncarcinogenic risk, while the major risk originated from Pb although leaded gasoline was prohibited before the venue establishment. Furthermore, the cancer risks (CRs) analysis showed the probable occurrence of carcinogenic health effects from Cd and Ni to adults and from Cd, Cr, and Ni to children. Furthermore, the Cd and Pb concentrations in the edible leaves of cabbage and radish growing in gardens were higher than the recommended maximum value. This study focused on the health risks of road dust directly impacted by vehicle emissions and provides accurate predictions of trace metal(loid) contamination sources in the urban environment.

Development and application of a high accuracy method for measuring Pb in blood

BACKGROUND

Lead (Pb) is an environmental pollutant, and human exposure is assessed by measuring blood Pb concentrations. Today, the use of Pb-based products is restricted, but the health effects of low Pb concentrations require investigation. For this, a high-accuracy method is needed. Here, we report a new inductively coupled plasma mass spectrometry (ICP-MS) method for quantifying Pb in blood.

METHODS

Blood samples and calibrators were gravimetrically spiked with bismuth as an internal standard, digested with ultrapure nitric acid, and diluted 100 times. The calibrators were made from high-purity reference materials supplied by the National Institute of Standards and Technology, and the sample concentration was measured using the calibration bracketing method. The analytical performance and application of the new method were investigated.

RESULTS

The method had good specificity and a negligible matrix effect. The intra- and inter-assay coefficients of variation (CVs) were <1.34 % and <1.88 %, respectively, and the total CV was <1.74 %. The range of recovery was 98.9 %-99.4 %. SRM955d, BCR-635, and BCR-636 were within the certified intervals, with mean relative bias values of 0.93 %, -0.13 %, and -0.56 %, respectively. The limit of quantification was 1.1 µg/l. The method was used to assign target values to external quality assessment samples and to assess routine methods, showing good results at high concentrations. However, at low concentrations, two laboratories did not pass.

CONCLUSIONS

This ICP-MS method is a simple, accurate method and can be a candidate reference method for blood Pb measurement. But more research will be needed to verify this.

Source apportionment based on lead isotope ratios: Could domestic dog's blood lead be used to identify the level and sources of lead pollution in children?

Domestic dogs have been proved to be used as "sentinel organisms" to monitor human lead exposure. However, whether dogs' blood can be used to identify the levels and pollution source of children's lead exposure still needs evidence. To evaluate the potential use of domestic dogs' blood lead as an indicator of lead exposure levels and pollution source of children, accompanying with potential environmental media samples, lead concentrations and isotope ratios (expressed as ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb) in blood were investigated and compared between children and dogs, who came from a Pb-Zn smelter area, a coal fired area and a control area without industrial activity. The results showed that there were significant correlations in blood lead levels (BLLs) between children and dogs in the study areas (p < 0.01). The lead isotope ratios (LIRs) in blood of children and dogs were disparate among the three areas, however, the LIRs of dogs were quite correlated with those of children in each area (p < 0.01). With the comparison of LIRs between potential pollution sources (slag, ore, coal, paint) and blood samples, the identified lead sources based on dogs' blood were found to be coincident with those based on children's blood. Ore smelting and coal combustion were the main sources of lead exposure for the dogs and children in the smelting area, and coal combustion was the predominant source for the children and dogs living in the coal burning area and control area. The results showed that dogs' BLLs might be used to estimate children's BLLs, and blood LIRs measurements of dogs' could be used as an alternative for identifying the sources of children's lead exposure. This study further provided relevant evidence for dogs to be sentinels exposed to human lead exposure and an alternative method for source apportionment of children's lead exposure.

Geochemical Contamination, Speciation, and Bioaccessibility of Trace Metals in Road Dust of a Megacity (Guangzhou) in Southern China: Implications for Human Health

Road dust has been severely contaminated by trace metals and has become a major health risk to urban residents. However, there is a lack of information on bioaccessible trace metals in road dust, which is necessary for an accurate health risk assessment. In this study, we collected road dust samples from industrial areas, traffic intersections, and agricultural fields from a megacity (Guangzhou), China, and conducted a geochemical enrichment, speciation, and bioaccessibility-based health risk assessment of trace metals. In comparison with local soil background values, the results revealed a significant accumulation of trace metals, including Zn, Cd, Cu, and Pb in the road dust, which is considered moderate to heavy pollution. Sequential extraction indicated that most trace metals in the road dust were primarily composed of a Fe/Mn oxide-bound fraction, carbonate-bound fraction, and residual fraction, while the dominant fraction was the organic matter-bound fraction of Cu, and the residual fractions of As, Cr, and Ni. The in vitro gastrointestinal (IVG) method revealed that high percentages of Zn, Cd, Cu, and As were bioaccessible, suggesting the possible dissolution of trace metals from adsorbed and carbonate-associated fractions in road dust exposed to the biological fluid matrix. The IVG bioaccessibility-based concentration largely decreased the noncarcinogenic health risk to a negligible level. Nevertheless, the entire population is still exposed to the cumulative probability of a carcinogenic risk, which is primarily contributed to by As, Cd, Cr, and Pb. Future identification of the exact sources of these toxic metals would be helpful for the appropriate management of urban road dust contamination.

Research Progress on Heavy Metals Pollution in the Soil of Smelting Sites in China

Contamination by heavy metals is a significant issue worldwide. In recent decades, soil heavy metals pollutants in China had adverse impacts on soil quality and threatened food security and human health. Anthropogenic inputs mainly generate heavy metal contamination in China. In this review, the approaches were used in these investigations, focusing on geochemical strategies and metal isotope methods, particularly useful for determining the pathway of mining and smelting derived pollution in the soil. Our findings indicate that heavy metal distribution substantially impacts topsoils around mining and smelting sites, which release massive amounts of heavy metals into the environment. Furthermore, heavy metal contamination and related hazards posed by Pb, Cd, As, and Hg are more severe to plants, soil organisms, and humans. It's worth observing that kids are particularly vulnerable to Pb toxicity. And this review also provides novel approaches to control and reduce the impacts of heavy metal pollution. Hydrometallurgy offers a potential method for extracting metals and removing potentially harmful heavy metals from waste to reduce pollution. However, environmentally friendly remediation of contaminated sites is a significant challenge. This paper also evaluates current technological advancements in the remediation of polluted soil, such as stabilization/solidification, natural attenuation, electrokinetic remediation, soil washing, and phytoremediation. The ability of biological approaches, especially phytoremediation, is cost-effective and favorable to the environment.

Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (Pb^HD) in Shanghai in order to determine the extent and exposure risks of Pb^HD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (Pb^IC). The mean concentration of Pb^HD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of Pb^IC of household dust samples (²⁰⁸Pb/²⁰⁶Pb: 2.1096 ± 0.0054; ²⁰⁷Pb/²⁰⁶Pb: 0.8648 ± 0.0025) are a close match to Pb^IC of coal combustion and solid waste incineration and fit well with those of outdoor air Pb^IC and urban surface soil Pb^IC of Shanghai. The study shows that children living in Shanghai are subject to Pb^HD exposure, with children living in the homes with lower average price having increased susceptibility to Pb^HD exposure. The data indicate that Pb^HD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.

Uneven development of the lead industry leads to regional differences in blood lead levels of children

Children's exposure to lead is a global health problem, especially in low- and middle-income countries. However, research on the relationship between children's blood lead levels (BLLs) and the development of the lead industry is still limited. This study examined whether children's BLLs were associated with the development of lead industry in different regions. Using survey data on the BLLs of children living in 250 prefectures in China with corresponding data on their economic factors and lead industries, we explored the regional variation of children's BLLs using statistical methods. The results show that the level of economic development in leaded areas was associated with inequity in children's BLLs and met the environmental Kuznets hypothesis. In areas without lead industries, there was little correlation between the level of economic development and the BLLs of children and thus the environmental Kuznets hypothesis was not supported. Lead mines, lead smelting and chemical companies are major sources of blood lead in children living in leaded areas. This study demonstrated the success of control policies for lead-acid battery manufacturers in promoting the prevention and control of childhood lead poisoning in China. China should consciously support the improvement of children's BLLs in undeveloped areas with lead industries through national financing and policies to avoid the continuous effects of the regional inequality problem of high children's BLLs.

Assessment of Urinary Lead (Pb) and Essential Trace Elements in Autism Spectrum Disorder: a Case-Control Study Among Preschool Children in Malaysia

Lead (Pb) is a heavy metal which is abundant in the environment and known to cause neurotoxicity in children even at minute concentration. However, the trace elements calcium (Ca), magnesium (Mg), zinc (Zn) and iron (Fe) are essential to children due to its protective effect on neurodevelopment. The primary objective of this study was to assess the role of Pb and trace elements in the development of autism spectrum disorder (ASD) among preschool children. A total of 81 ASD children and 74 typically developed (TD) children aged between 3 and 6 years participated in the study. Self-administered online questionnaires were completed by the parents. A first-morning urine sample was collected in a sterile polyethene urine container and assayed for Pb, Ca, Mg, Zn and Fe using an inductively coupled plasma mass spectrometry (ICP-MS). Comparisons between groups revealed that the urinary Pb, Mg, Zn and Fe levels in ASD children were significantly lower than TD children. The odds of ASD reduced significantly by 5.0% and 23.0% with an increment of every 1.0 μg/dL urinary Zn and Fe, respectively. Post interaction analysis showed that the odds of ASD reduced significantly by 11.0% and 0.1% with an increment of every 1.0 μg/dL urinary Zn and Pb, respectively. A significantly lower urinary Pb level in ASD children than TD children may be due to their poor detoxifying mechanism. Also, the significantly lower urinary Zn and Fe levels in ASD children may augment the neurotoxic effect of Pb.

Environmental health survey for children residing near mining areas in South Gobi, Mongolia

Background

We evaluated the level and factors of heavy metal exposure to children residing in the Togttsetsii, Khanbogd, and Bayandalai soums of South Gobi province, Mongolia.

Methods

A total of 118 children aged 9–12 years were surveyed, and the level of heavy metal exposure in their bodies was investigated. Exposure was investigated by measuring concentrations of heavy metals such as cadmium, lead, and mercury in the blood; mercury concentration in the hair; and total arsenic in the urine.

Results

Blood cadmium concentration had geometric averages of 0.16 µg/L in the children from Bayandalai, 0.15 µg/L Tsogttsetsii, and 0.16 µg/L Khanbogd. Blood lead concentration showed a relatively higher geometric average of 7.42 µg/dL in the children from Bayandalai compared to 4.78 µg/dL and 5.15 µg/dL in those from Tsogttsetsii and Khanbogd, respectively. While blood mercury concentration was the highest in the children from Bayandalai, with a value of 0.38 µg/L, those from Tsogttsetsii and Khanbogd had similar concentrations of 0.29 µg/L and 0.29 µg/L, respectively. Hair mercury concentration was the highest in the children from Bayandalai, with a value of 78 µg/g, a particularly significant difference, with a concentration of 0.50 µg/g in those from Khanbogd. Urine arsenic concentration was the highest in the children from Khanbogd, with a value of 36.93 µg/L; it was 26.11 µg/L in those from Bayandalai and 23.89 µg/L in those from Tsogttsetsii.

Conclusions

The high blood lead concentration of children in Bayandalai was judged to be due to other factors in addition to mine exposure; the reason why blood and hair mercury concentration was higher in children from Bayandalai may have been due to exposure to many small-scale gold mines in the area. In the case of Khanbogd, it was estimated that the high arsenic level in urine was caused by the effect of mines.

Increased intestinal permeability with elevated peripheral blood endotoxin and inflammatory indices for e-waste lead exposure in children

Lead (Pb) entering the body through different channels can damage the function of intestinal mucosal barrier and cause the body stressful inflammatory response to enhance. This study conducted a cross-sectional study to investigate the effects of Pb exposure on intestinal permeability in children by measuring the level of bacterial endotoxin and index of inflammatory cell types in peripheral blood. From November to December 2018, we recruited 187 participants aged 3-6 years by stratified randomization, from an electronic-waste-exposed group (n = 82) and a referent group (n = 105). General demographic information, past history of the digestive system in child, and family situation were informed by children's guardians with questionnaires. Children in the exposed group showed lower weight, height, and body mass index while more diarrhea in a month. Blood Pb and plasma endotoxin were elevated in exposed children than referent children and the positive relationship between them was shown in all children [B (95% CI): 0.072 (0.008, 0.137), P = 0.033]. Peripheral monocyte counts and leukotriene B₄ (LTB₄) levels were significantly increased in the exposed group. Endotoxin levels were positively correlated with neutrophils, monocytes, and LTB₄ [B (95% CI): 0.054 (0.015, 0.093), 0.018 (0.005, 0.031), and 0.049 (0.011, 0.087), respectively, P < 0.05]. To sum up, the exposed children showed lower physical growth levels, poorer gut health, and increased intestinal permeability, which was related to high blood Pb and peripheral inflammatory indices. These results suggest the possible adverse impact of environmental Pb exposure on the intestinal health of children.

Blood lead levels of Chinese children from 1991 to 2020: Based on Monte Carlo simulation

Chinese children have been exposed to high level of lead due to polluted air, dust, contaminated foods and water, etc. In this research, we investigated published blood lead levels (BLLs) reflecting 1,057,832 Chinese children aged at 0-12 and teenagers aged at 13-18 in the past 30 years (1991-2020). The data mining and estimation were performed innovatively by Monte Carlo simulation to remedy the skewed distribution-induced bias. The temporal trend of Chinese children's BLLs showed an obvious decrease in the past decades from 88.74 μg/L (Geometric SD = 4.09) during 1991-1995 to 27.32 μg/L (Geometric SD = 4.18) during 2016-2020. This study also indicated that children's BLLs of Yunnan, Guizhou, Shanxi were at relatively high levels and most provinces showed a downward trend. Chinese boys aged at 1-18 years old had higher BLLs (GM: 44.03 μg/L) compared to girls (GM: 41.32 μg/L) (p < 0.001). At different age groups, Chinese children's BLLs were 42.04 μg/L (1-3 years old), 52.88 μg/L (4-6 years old), 50.49 μg/L (7 and above years old), respectively. Although the BLLs of Chinese children exhibited a continuous declined trend in the past 30 years, it was still higher than that in developed countries, which indicated that more efforts are needed in children's BLLs control.

Regional characteristics of children's blood lead levels in China: A systematic synthesis of national and subnational population data

The blood lead levels (BLLs) of children in China remain notably high in many areas. We aimed to summarise the relevant regional characteristics, identifying problematic areas and the causes of lead pollution. We searched the databases of PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang Data, systematically reviewing 219 articles published from January 2010 to September 2020. In doing so, we assessed the BLLs noted in 220 prefectures across China. Data were organised using Geographic Information Systems (GIS) mapping. Out of a total of 629,627 children sampled, we found that the average blood lead level (BLL) of children included in our study is 50.61 ± 13.63 μg/L, which slightly exceeds the 50.00 μg/L US standard. Within the sample, 8.75% had BLLs higher than 100.00 μg/L. Children living in Liaoning, Hebei, Shanxi, Jiangxi, Anhui, Fujian, Guizhou, Yunnan, and Guangxi had notably high BLLs, at more than 60.00 μg/L. A total of 112 municipalities had an average children's BLL above 50.00 μg/L. Furthermore, Chenzhou, Linfen, Yuncheng, and Hechi had the highest children's BLLs, with average values above 100.00 μg/L. The leading contributors to lead pollution are lead mining, lead recovery and the smelting industry. Nonetheless, the lead-acid battery industry needs more attention. Although data suggest that BLLs are decreasing in China, many areas still have high BLLs that need to be monitored. Moreover, national standards must improve to decrease acceptable BLL thresholds for children.

A novel calibration for L-shell x-ray fluorescence measurements of bone lead concentration using the strontium Kβ/Kαratio

Objective. Lead (Pb) is a well-known toxic element.In vivobone Pb concentration measurement is a long-term exposure metric complementary to blood Pb concentration measurement which is a metric of recent exposure.In vivohuman tibia bone Pb measurements using Pb K-shell or L-shell x-ray fluorescence (KXRF or LXRF) emissions were developed in the 1980s. KXRF bone Pb measurements using Cd-109 gamma rays and coherent-to-fluorescence ratio to account for differences between phantom andin vivomeasurements, was employed in human studies. Bone Pb LXRF method employed x-ray tubes. However, calibration procedures using ultrasound measurements of the soft tissue thickness (STT) proved inaccurate.Approach. In this study, bone and soft tissue (ST) phantoms simulatedin vivobone Pb measurements. Seven plaster-of-Paris cylindrical bone phantoms containing 1.01 mg g-1of strontium (Sr) were doped with Pb in 0, 8, 16, 29, 44, 59, and 74 μg g-1concentrations. Polyoxymethylene (POM), resin, and wax were each used to fabricate four ST phantoms in the approximate 1-4 mm thickness range. Pb LXRF measurements were performed using a previously developed optimal grazing incidence position method.Main results. Linear attenuation coefficients measurements of ST materials indicated that POM and resin mimicked well attenuation of Pb x-rays in skin and adipose tissue, respectively. POM and resin data indicated a bone Pb detection limit of 20 μg g-1for a 2 mm STT. Derived relationships between the Pb concentration, Pb LXRF and Sr Kβ/Kαratio data did not require STT knowledge. Applied to POM and resin data, the new calibration method yielded unbiased results.Significance.In vivobone Pb measurements in children were suggested following considerations of radiation dose, STT, detectability and distribution of Pb and Sr in bone. This research meets with the concerns regarding the negative effects of low levels of Pb exposure on neurodevelopment of children.

Time for a change in blood lead reference value for Chinese children

In China, the first and also the latest version of national childhood lead exposure control guidelines was issued by the National Health Commission in 2006, when the reference value of high blood lead exposure was set at 100 μg/L and lead poisoning was set at 200 μg/L. Lead exposure levels have been decreasing in China over the last few decades, with almost all blood lead concentrations in children under 7 years of age being under 100 μg/L in non-industrial areas. However, lead concentrations lower than 100 μg/L in blood in children are associated with neurodevelopmental deficits. Thus, if the reference value remains at a high level, a large percent of children with exposure levels that are high but lower than the current reference value will be diagnosed as 'safe' and be ignored. Thus, we appeal that the reference value should be lowered according to local actual exposure level. A more stringent reference value would give care givers, doctors, communities, and officials more opportunities to take action earlier.

Biomonitoring of Lead Exposure in Children from Two Fishing Communities at Northern Colombia

Lead (Pb) exposure is a growing concern in developing countries, especially in vulnerable children. The objective of this study was to evaluate blood lead levels (BLL) in children from two fishing populations at Northern Colombia, Loma de Arena and Tierrabomba, as well as their association with morphometric parameters, markers of hematological status, liver function, and mRNA expression of genes related to Pb toxicity. A total of 198 blood samples were collected from participants aged 5-16 years old. The mean (± standard error) BLL for the studied sample was 3.6 ± 0.3 μg/dL, and the 97.5th percentile was 21.0 μg/dL. The participants of Loma de Arena and Tierrabomba presented BLL of 3.9 ± 0.5 and 2.9 ± 0.3 μg/dL, respectively. Children born preterm had greater BLL than those born at full term. Boys had greater BLL than girls, which also occurred for participants between 12 and 16 years old, compared with those aged 5-11 years old. The BLL were negatively correlated with body mass index in children from Loma de Arena, but an opposite behavior was observed for Tierrabomba. In Loma de Arena, the mRNA expression of interferon gamma, a pro-inflammatory cytokine, increased with the BLL, but that of δ-aminolevulinic acid dehydrogenase, a sensor for Pb poisoning, decreased. In Tierrabomba, gene expression did not change with BLL. These results show that in fishing communities, lead exposure promotes different health impacts depending on age, sex, and other site-specific factors. In any case, appropriate educational and intervention programs should be carried out to minimize Pb exposure in children.

Distribution patterns and sources of heavy metals in soils from an industry undeveloped city in Southern China

The accumulations of heavy metals in urban soils are derived from natural parent materials and complex anthropogenic emission sources. This paper investigated metal contamination in urban soils at an industry undeveloped city (Haikou) in southern China, an ideal place to quantitatively assess the contribution of metals from different sources. The concentrations of most heavy metals in the urban soils of Haikou were much lower than their guideline values and that of those from other big cities in China. In contrast, the chemical speciation of metals in this study was similar to those from other cities. The spatial distributions of heavy metals and principal component analysis (PCA) revealed that basaltic parent materials, traffic emissions, and coal combustion were the main factors controlling the distribution of metals in the soils. The Pb isotope signatures of the Haikou soils were greatly different from those of the Beijing and Shanghai soils, but similar to those of the Guangzhou soils, suggesting the common sources of Pb in southern China cities. The results of ternary mixing model of Pb isotopes showed that the contributions of Pb from natural background, coal combustion and traffic emission sources were 5.3-82.4% (mean: 39.7 ± 21.1%), 0-85.7% (mean: 25.5 ± 24.6%), and 1.9-64% (mean: 34.8 ± 22.9%), respectively. This suggests that traffic emission is still the most important anthropogenic source of Pb in Haikou.

Environmental Pollution Effect Analysis of Lead Compounds in China Based on Life Cycle

Environmental pollution caused by lead toxicity causes harm to human health. Lead pollution in the environment mainly comes from the processes of mining, processing, production, use, and recovery of lead. China is the world’s largest producer and consumer of refined lead. In this paper, the material flow analysis method is used to analyze the flow and direction of lead loss in four stages of lead production, manufacturing, use, and waste management in China from 1949 to 2017. The proportion coefficient of lead compounds in each stage of lead loss was determined. The categories and quantities of lead compounds discharged in each stage were calculated. The results show that in 2017, China emitted 2.1519 million tons of lead compounds. In the four stages of production, manufacturing, use, and waste management, 137.9 kilo tons, 209 kilo tons, 275 kilo tons, and 1.53 million tons were respectively discharged. The emissions in the production stage are PbS, PbO, PbSO₄, PbO₂, Pb₂O₃, and more. The emissions during the manufacturing phase are Pb, PbO, PbSO₄, Pb₂O₃, Pb₃O₄, and more. The main emissions are Pb, PbO, Pb₂O₃, Pb₃O₄, and more. The main emissions in the waste management stage are PbS, Pb, PbO, PbSO₄, PbO₂, PbCO₃, Pb₂O₃, Pb₃O₄, and more. Among them, the emissions of PbSO₄, PbO, Pb, and PbO₂ account for about 90%, which are the main environmental pollution emissions. The waste management stage is an important control source of lead compound emission and pollution. In view of these characteristics of the environmental pollution risk of lead compounds in China, the government should issue more targeted policies to control lead pollution.

Occurrence and Fate of Heavy Metals in Municipal Wastewater in Heilongjiang Province, China: A Monthly Reconnaissance from 2015 to 2017

As one of the major sources of pollutions in the environments, effluents from municipal wastewater recently became a hot topic. This study quantified monthly county-level releases of five heavy metals, i.e., lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and mercury (Hg), from municipal wastewater into the environment in the Heilongjiang Province of China, based on sampling, measurement, and modeling tools. Wastewater samples were collected from 27 municipal wastewater treatment plants (MWTPs) in 15 county-level cities of Heilongjiang every month from 2015 to 2017. The concentrations of five heavy metals were analyzed in both influents (Pb: 160 ± 100 μg/L; Cd: 15 ± 9.0 μg/L; Cr: 170 ± 64 μg/L; Hg: 0.67 ± 1.5 μg/L; As: 6.2 ± 4.8 μg/L) and effluents (Pb: 45 ± 15 μg/L; Cd: 5.2 ± 5.1 μg/L; Cr: 57 ± 13 μg/L; Hg: 0.28 ± 0.12 μg/L; As: 2.6 ± 1.4 μg/L). The removal ratios of the five heavy metals ranged from 50% to 67%. Inflow fluxes of Pb, Cr, and Cd displayed increasing trends first then decreased after reaching a maximum value, whereas those of Hg and Pb remained stable. Material flow analysis reveals that constructions of MWTPs are conducive to significantly reduce the releases of heavy metals from urban areas into the aquatic environment in the study area. Additionally, municipal wastewater sludge (used as fertilizer or spread on the land) could be a significant source of heavy metals in the land.