Effect of lead pollution control on environmental and childhood blood lead level in Nantong, China: an interventional study

Independent and joint associations of multiple metals exposure with vital capacity index: a cross-sectional study in Chinese children and adolescents

OBJECTIVE

The current study aimed to explore the relationships between urinary metals and vital capacity index (VCI) in 380 children and adolescents in Northeast China using a variety of statistical methods.

METHODS

A cross-sectional survey was conducted among 380 children and adolescents in Liaoning Province, China. To assess the relationships between urinary metals and VCI, Elastic-net (ENET) regression, multivariate linear regression, weighted quantile sum (WQS), bayesian kernel machine regression (BKMR) and quantile-based g computation (qgcomp) were adopted.

RESULTS

The ENET model selected magnesium (Mg), vanadium (V), manganese (Mn), arsenic (As), tin (Sn) and lead (Pb) as crucial elements. In multiple linear regression, we observed urinary Pb, Mn was negatively correlated with VCI individually in both total study population and adolescents (all p values < 0.05) in the adjustment model. The WQS indices were negatively related with VCI in total study population (β=-3.19, 95%CI: -6.07, -0.30) and adolescents (β=-3.46, 95%CI: -6.58, -0.35). The highest weight in total study population was Pb (38.80%), in adolescents was Mn (35.10%). In the qgcomp, Pb (31.90%), Mn (27.20%) were the major negative contributors to the association in the total population (β=-3.51, 95%CI: -6.29, -0.74). As (42.50%), Mn (39.90%) were the main negative contributors (β=-3.95, 95% CI: -6.68, -1.22) among adolescents. The results of BKMR were basically consistent with WQS and qgcomp analyses.

CONCLUSIONS

Our results indicated that Pb and Mn were priority toxic materials on VCI. The cumulative effect of metals was negatively related to VCI, and this relationship was more pronounced in adolescents.

Fate, source apportionment and fractionation of potentially toxic elements in agricultural soil around a densely populated, semiarid urban center of India: baseline study and ecological risk assessment

This study is on the outskirts of the rapidly growing city of Jaipur, located in the semiarid region of India and gateway to the 'Great Indian Thar' desert, and focused on potentially toxic elements (PTE) pollution in the farmlands around the city. Concentrations of PTE, along with associated soil parameters such as pH, available nitrogen, organic carbon, phosphorus, and potassium, were estimated in agricultural soil samples near an industrial region on the outskirts of the capital city of the largest state of India. The PTE concentrations in the soil were in the following order: Mn > Pb > Ni > Cr > Cu > Cd. Soil pollution indices, such as the geochemical accumulation index (Igeo), contamination factor (CF), and ecological risk index (ERI), indicated that the soil was moderately to highly polluted. The result of BCR extraction techniques showed Cd is found mainly in the exchangeable and residual fractions, Pb, Mn were found in the reducible as well as residual fractions, while other PTE were mostly bound to residual fraction. All other PTEs are primarily found in the residual fraction, tightly linked with the silicate lattice of soil minerals. Multivariate analysis and the Pearson correlation matrix indicate a common source apportionment for Pb and Cd. Cd, and Pb concentrations in agricultural soil indicate ecological harm that warrants immediate attention and policy-level intervention.

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.

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.

The association between multi-heavy metals exposure and lung function in a typical rural population of Northwest China

BACKGROUND

Heavy metal exposure is acknowledged to be associated with decrease of lung function, but the relationship between metals co-exposure and lung function in rural areas of Northwest China remains unclear, particularly in an area famous for heavy metal pollution and solid fuel use. Therefore, the purpose of this study is to explore the effects of heavy metal exposure on lung function and the potential impacts of living habit in a rural cohort of Northwest China.

METHODS

The study area included five villages of two regions in Northwestern China-Gansu province. All participants were recruited from the Dongdagou-Xinglong (DDG-XL) rural cohort in the study area. Urine levels of 10 common and representative heavy metals were detected by ICP-MS, including Cobalt (Co), Nickel (Ni), Molybdenum (Mo), Cadmium (Cd), Stibium (Sb), Copper (Cu), Zinc (Zn), Mercury (Hg), Lead (Pb), and Manganese (Mn). The lung function was detected by measuring percentages of predicted forced vital capacity (FVC%) and predicted forced expiratory volume in one second (FEV1%) as well as the ratio of FEV1/FVC. We also analyzed the association between heavy metals and pulmonary ventilation dysfunction (PVD). Restricted cubic spline, logistic regression, linear regression, and bayesian kernel machine regression (BKMR) model were used to analyze the relationship between heavy metal exposure and lung function.

RESULTS

Finally, a total of 382 participants were included in this study with an average age of 56.69 ± 7.32 years, and 82.46% of them used solid fuels for heating and cooking. Single metal exposure analysis showed that the higher concentration of Hg, Mn, Sb, and lower Mo may be risk factors for PVD. We also found that FEV1% and FVC% were negatively correlated with Sb, Hg, and Mn, but positively correlated with Mo. The effect of mixed heavy metals exposure could be observed through BKMR model, through which we found the lung function decreased with the increase of heavy metal concentration. Furthermore, the males, BMI ≥ 24 kg/m2 and who used solid fuels showed a higher risk of PVD when exposed to Co, Zn, and Hg.

CONCLUSIONS

Our results suggested that heavy metal exposure was associated with decrease of lung function regardless of single exposure or mixed exposure, particularly for Sb, Hg, Mn and those who use solid fuels.

Dissolved organic matters-enhanced Pb releases from nano- or submicron Pb sulfides and oxides

Diverse lead (Pb) particles possess different ecological risks not only due to their own toxicity differences but also because of different abilities to release toxic dissolved Pb. Dissolved organic matter (DOM) was a key factor influencing dissolution processes of metal particles. However, impacts of DOM on dissolution of different Pb nano- or submicron particles were not known yet. Herein, impacts of DOM on dissolution kinetics of lead sulfide (PbS), lead sulfate (PbSO₄), lead monoxide (PbO), lead tetroxide (Pb₃O₄) and lead dioxide (PbO₂) nano- or submicron particles were firstly investigated taking Pahokee Peat humic acid (PPHA) as an example. Results indicated PPHA improved the suspending stability of Pb particles through electrostatic repulsion, and enhanced releases of dissolved Pb. Final concentration of dissolved Pb was raised by 1.22-8.82 times with PPHA. This was attributed to ligand exchange interactions between PPHA and Pb particles. Theoretical computations indicated that not only sorption or ligand exchange energy, but also numbers of ligands on the surface of particles were key factors governing impacts of PPHA on dissolved Pb. This study provided a new mechanism insight into dissolution behavior of various Pb particles and will be beneficial to their ecological risk assessment.

Effects of various Fe compounds on the bioavailability of Pb contained in orally ingested soils in mice: Mechanistic insights and health implications

Reducing lead (Pb) exposure via oral ingestion of contaminated soils is highly relevant for child health. Elevating dietary micronutrient iron (Fe) intake can reduce Pb oral bioavailability while being beneficial for child nutritional health. However, the practical performance of various Fe compounds was not assessed. Here, based on mouse bioassays, ten Fe compounds applied to diets (100-800 mg Fe kg^-1) reduced Pb oral relative bioavailability (RBA) in two soils variedly depending on Fe forms. EDTA-FeNa was most efficient, which reduced Pb-RBA in a soil from 79.5 ± 14.7 % to 23.1 ± 2.72 % (71 % lower) at 100 mg Fe kg^-1 in diet, more effective than other 9 compounds at equivalent or higher doses (3.6-68 % lower). When EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous bisglycinate were supplemented, Fe-Pb co-precipitation was not observed in the intestinal tract. EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous sulfate suppressed duodenal divalent metal transporter 1 (DMT1)mRNA relative expression similarly (27-68 % lower). In comparison, among ten compounds, EDTA-FeNa elevated Fe concentrations in mouse liver, kidney, and blood (1.50-2.69-fold higher) most efficiently, suggesting the most efficient Fe absorption that competed with Pb. In addition, EDTA was unique from other organic ligands, ingestion of which caused 12.0-fold higher Pb urinary excretion, decreasing Pb concentrations in mouse liver, kidney, and blood by 68-88 %. The two processes (Fe-Pb absorption competition and Pb urinary excretion with EDTA) interacted synergistically, leading to the lowest Pb absorption with EDTA-FeNa. The results provide evidence of a better inhibition of Pb absorption by EDTA-FeNa, highlighting that EDTA-FeNa may be the most appropriate supplement for intervention on human Pb exposure. Future researches are needed to assess the effectiveness of EDTA-FeNa for intervention on human Pb exposure.

Toxic Metals in Particulate Matter and Health Risks in an E-Waste Dismantling Park and Its Surrounding Areas: Analysis of Three PM Size Groups

Heavy metals generated from e-waste have created serious health risks for residents in e-waste disposal areas. This study assessed how airborne toxic metals from an e-waste dismantling park (EP) influenced surrounding residential areas after e-waste control. PM_2.5, PM₁₀, and total suspended particles (TSP) were sampled from 20 sites, including an EP, residential areas, and an urban site; ten kinds of metals were analyzed using ICP-MS and classified as PM_2.5, PM_2.5-10, and PM_10-100. Results showed that metals at the EP tended to be in coarser particles, while metals from residential areas tended to be in finer particles. A source analysis showed that metals from the EP and residential areas may have different sources. Workers' cancer and non-cancer risks were higher when exposed to PM_2.5-10 metals, while residents' risks were higher when exposed to PM_2.5 metals. As and Cr were the most strongly associated with cancer risks, while Mn was the most strongly associated with the non-cancer risk. Both workers and residents had cancer risks (>1.0 × 10^-6), but risks were lower for residents. Therefore, e-waste control can positively affect public health in this area. This study provides a basis for further controlling heavy metal emissions into the atmosphere by e-waste dismantling and encouraging worldwide standardization of e-waste dismantling.

Source Analysis and Contamination Assessment of Potentially Toxic Element in Soil of Small Watershed in Mountainous Area of Southern Henan, China

In this study, the concentrations of potentially toxic elements in 283 topsoil samples were determined. Håkanson toxicity response coefficient modified matter element extension model was introduced to evaluate the soil elements contamination, and the results were compared with the pollution index method. The sources and spatial distribution of soil elements were analyzed by the combination of the PMF model and IDW interpolation. The results are as follows, 1: The concentration distribution of potentially toxic elements is different in space. Higher concentrations were found in the vicinity of the mining area and farmland. 2: The weight of all elements has changed significantly. The evaluation result of the matter-element extension model shows that 68.55% of the topsoil in the study area is clean soil, and Hg is the main contamination element. The evaluation result is roughly the same as that of the pollution index method, indicating that the evaluation result of the matter-element extension model with modified is accurate and reasonable. 3: Potentially toxic elements mainly come from the mixed sources of atmospheric sedimentation and agricultural activities (22.59%), the mixed sources of agricultural activities and mining (20.26%), the mixed sources of traffic activities, nature and mining (36.30%), the mixed sources of pesticide use and soil parent material (20.85%).

Pollutant source, ecological and human health risks assessment of heavy metals in soils from coal mining areas in Xinjiang, China

This study aims to analyze the pollution characteristics and sources of heavy metal elements for the first time in the Zhundong mining area in Xinjiang using the linear regression model. Additionaly, the health risks with their probability and infleuencing factors on different groups of people's were also evaluated using Monte Carlo (MC) simulation approach. The results shows that 89.28% of Hg was from coal combustion, 40.28% of Pb was from transportation, and 19.54% of As was from atmospheric dust. The main source of Cu and Cr was coal dust, Hg has the greatest impact on potential ecological risks. which accounted for 60.2% and 81.46% of the Cu and Cr content in soil, respectively. The all samples taken from Pb have been Extremely polluted (100%). 93.3% samples taken from As have been Extremely polluted. The overall potential ecological risk was moderate. Adults experienced higher non-carcinogenic risks of heavy metals from their diets than children. Interestingly, body weight was the main factor affecting the adult's health risks. This research provides more comprehensive information for better soil management, soil remediation, and soil pollution control in the Xinjiang mining areas.

Inventory of Pb emissions from one of the largest historic Pb smelter worldwide: 118-year legacy of Pb pollution in northern Mexico

The atmospheric Pb emissions (1901-2019), from one of the world's largest non-ferrous metallurgical complexes (Met-Mex in Torreón, México), were estimated based on historical records of modifications in the design, processes, and production volumes. Eight historical periods, with differing amounts of Pb emissions, were distinguished: (1) Essentially no controls (1901-1960); (2) migration to limited controls (1961-1972) by conversion to a Pb-Zn smelter-refining complex and installation of SO₂ collectors in 1961-1963; (3) completion to limited control (1973-1977) by the installation of a third H₂SO₄ collector and a low-efficiency filtration system; (4) maintenance of limited control with no changes (1978-1987); (5) migration to strict control (1988 to 1998) by updating H₂SO₄ collectors and installation of fertilizer and SO₂ liquid extraction plants; (6) completion to strict control (1999-2000) by the installation of state-art technology filtration systems and roofing working areas; (7) migration to abatement (2001-2003) by implantation of good management practices; and (8) maintenance of abatement following good management practices (2004-2019). Based on differences between those periods, we reconstructed the evolution of the Pb emission reduction efficiency (ER in %) and Pb emission factors (EF in gram/ton) for the Torreón complex. Pb emitted by the complex over the past 118 years totaled 23,350-27,580 t, with most of it (63-75%) occurring when emission controls were negligible (pre-1960 period). In comparisons with other facilities worldwide (e.g., the USA, Canada, and Europa), the modification in Met-Mex for control the Pb emission occurred several years. Emissions from the primary Pb-Zn smelter-refining are released mostly to the atmosphere from the sintering, smelting, drossing, and refining. While Pb emissions from the facility have declined by over an order of magnitude to contemporary levels (≤ 12.6 t/year), the current Pb rates still account for atmospheric Pb levels that are 2-3 times higher the USEPA standard and still constitutes a major health threat in Torreón.

Elevated levels of lead exposure and impact on the anti-inflammatory ability of oral sialic acids among preschool children in e-waste areas

The oral health of preschool children in an electronic waste (e-waste) area is susceptible to lead (Pb) exposure increasing the risk of dental caries and causing periodontitis and other oral diseases. The aim of the present study is to investigate the relationship between chronic exposure to Pb and oral anti-inflammatory potential of preschool children. For this analysis, 574 preschool children from 2.5 to 6 years of age were recruited between November and December 2017, in which 357 preschool children were from Guiyu (n = 357), an e-waste-contaminated town, and 217 from Haojiang Shantou. We measured the levels of child blood Pb, salivary sialic acid, serum interleukin-6 (IL-6) and serum tumor necrosis factor-α (TNF-α), and investigated the prevalence of dental caries in deciduous teeth. The medians of blood Pb levels, serum IL-6 and TNF-α were significantly higher in the Guiyu children than in Haojiang children. Concomitantly, salivary sialic acids were lower in the Guiyu children [9.58 (3.97, 18.42) mg/dL] than in Haojiang [17.57 (5.95, 24.23) mg/dL]. Additionally, the prevalence of dental caries in deciduous teeth was significantly higher in the Guiyu children than in Haojiang (62.5% vs. 53.9%). Blood Pb levels were negatively correlated with salivary sialic acids, in which IL-6 played as a mediator of the association between blood Pb levels and saliva sialic acid concentrations according to the mediation model. To our knowledge, this is the first report on the potential association between chronic Pb exposure and the anti-inflammatory ability of oral sialic acids among preschool children. These results suggest that the chronic Pb exposure can reduce salivary sialic acid levels, attenuate oral anti-inflammatory potential and increase the potential risk of dental caries in deciduous teeth among preschool children in an e-waste site.

A highly sensitive, selective and renewable carbon paste electrode based on a unique acyclic diamide ionophore for the potentiometric determination of lead ions in polluted water samples

Due to the toxicity of lead(ii) to all living organisms as it destroys the central nervous system leading to circulatory system and brain disorders, the development of effective and selective lead(ii) ionophores for its detection is very important. In this work, 1,3-bis[2-(N-morpholino)acetamidophenoxy]propane (BMAPP), belonging to acyclic diamides, was applied as a highly selective lead(ii) ionophore in a carbon paste ion selective electrode for the accurate and precise determination of Pb(ii) ions even in the presence of other interfering ions. Factors affecting the electrode's response behavior were studied and optimized. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and FT-IR spectroscopy were used for studying the morphology and response mechanism of the prepared sensor. The lipophilicity of the used ionophore, which contributes to the mechanical stability of the sensor, was studied using the contact angle measurement technique. The selectivity coefficients obtained by the separate solution method (SSM) and fixed interference method (FIM) confirmed the selectivity of the proposed sensor for Pb(ii) ions. The proposed sensor exhibited a Nernstian slope of 29.96 ± 0.34 mV per decade over a wide linear range of 5 × 10⁻⁸ to 1 × 10⁻¹ mol L⁻¹ and detection limit of 3 × 10⁻⁸ mol L⁻¹ for 2 months with a fast response time (<10 s) and working pH range (2.5–5.5). To further ensure the practical applicability of the sensor, it was successfully applied for the lead(ii) ion determination in different water samples and the obtained data showed an agreement with those obtained by atomic absorption spectroscopy. In addition, it was successfully applied for the potentiometric titration of Pb(ii) against K₂CrO₄ and Na₂SO₄.

Due to the toxicity of lead(ii) to all living organisms destroying the central nervous system and leading to circulatory system and brain disorders, the development of effective and selective lead(ii) ionophores for its detection is very important.

Status of cadmium accumulation in agricultural soils across China (1975-2016): From temporal and spatial variations to risk assessment

Based on 1186 published studies, the first national-scale assessment of cadmium (Cd) contamination in agricultural soils across China was conducted. Cd concentrations, temporal and spatial variations, and ecological and health risks resulted from Cd exposure were analyzed. A small part of sampling sites with Cd concentration surpass the screening value and the control value (GB15618-2018), respectively. Soil Cd concentrations in South China were higher than other regions. Ecological risks resulting from Cd contamination were low. Soil Cd concentrations accumulated gradually from 1981 to 2016. Cd mainly came from anthropogenic activities, such as mining, smelting, sewage irrigation, and fertilization. Linear correlations were observed between application amounts of fertilizers and Cd concentrations in soil, indicating that the application of nitrogen, phosphorus, potassium, and compound fertilizers is an important contributor of Cd in soils. This study details the overall Cd contamination status of agricultural soils in China, thus can provide insights for policymakers regarding contamination prevention measures.

Status of lead accumulation in agricultural soils across China (1979-2016)

The first national-scale assessment of lead (Pb) contamination in agricultural soils across China was conducted based on >1900 articles published between 1979 and 2016. Pb concentrations, temporal and spatial variations, and influencing factors were analyzed. Children's blood lead levels (BLLs) were also estimated using the integrated exposure uptake biokinetic (IEUBK) model. Pb concentrations in different areas of China varied greatly, which was closely associated with the distribution of Pb-related industries, especially Pb-zinc mine smelting, non-ferrous polymetallic mine smelting, e-waste recycling, and leaded gasoline consumption. The year 2000 was a significant transition year for Pb concentrations, with a rapid increase pre-2000 and a subsequent slow upward trend. Pb concentrations were found to be strongly associated with indicators of economic and social development including gross domestic product (GDP), population size, and vehicle ownership. Leaded gasoline, coal combustion, and non-ferrous smelting were the main sources of atmospheric Pb during the different periods. Predicted BLLs were higher in South China than those in the north. This study details the overall Pb contamination status of agricultural soils in China, and thus provides insights for policymakers with respect to pollution prevention measures.

A review of soil heavy metal pollution from industrial and agricultural regions in China: Pollution and risk assessment

Soil heavy metal pollution has been becoming serious and widespread in China. To date, there are few studies assessing the nationwide soil heavy metal pollution induced by industrial and agricultural activities in China. This review obtained heavy metal concentrations in soils of 402 industrial sites and 1041 agricultural sites in China throughout the document retrieval. Based on the database, this review assessed soil heavy metal concentration and estimated the ecological and health risks on a national scale. The results revealed that heavy metal pollution and associated risks posed by cadmium (Cd), lead (Pb) and arsenic (As) are more serious. Besides, heavy metal pollution and associated risks in industrial regions are severer than those in agricultural regions, meanwhile, those in southeast China are severer than those in northwest China. It is worth noting that children are more likely to be affected by heavy metal pollution than adults. Based on the assessment results, Cd, Pb and As are determined as the priority control heavy metals; mining areas are the priority control areas compared to other areas in industrial regions; food crop plantations are the priority control areas in agricultural regions; and children are determined as the priority protection population group. This paper provides a comprehensive ecological and health risk assessment on the heavy metals in soils in Chinese industrial and agricultural regions and thus provides insights for the policymakers regarding exposure reduction and management.

How Does Low Socioeconomic Status Increase Blood Lead Levelsin KoreanChildren?

Although studies have shown that a low socioeconomic status (SES) is associated with high blood lead levels (BLLs) in children, the mechanism underlying this observation is not well known. To determine how SES influences BLLs via environmental factors in Korean children, we conducted a population-based cross-sectional study of 4744 children aged 5–13 years. Questionnaires on sociodemographic information, environmental factors, and food consumption were administered to the children’s parents. BLLs in the study subjects were measured.The complete set of hypothesized associations was assessed using regression analysis and structural equation modeling. SES was associated with high BLLs. The total effects of nutritional factors, lead in the air and total length of nearby roads, and agriculture on BLLs were −0.062 (p < 0.001), 0.068 (p = 0.005), and 0.038 (p = 0.035), respectively. The direct effects of playing outdoors and SES on BLLs were 0.113 (p < 0.001) and −0.111 (p < 0.001), respectively. Although playing outdoors had a greater direct effect on BLLs than did SES, the total effect of SES (standardized β = −0.132, p < 0.001) was greater than that of other sources owing to indirect effects (β = −0.020, p = 0.004). A low SES was a major risk factor for elevated BLLs via environmental factors.

Effects of Pb Smelting on the Soil Bacterial Community near a Secondary Lead Plant

Secondary lead smelting is a widespread industrial activity which has exacerbated Pb or Cd contamination of soil and water across the world. Soil physicochemical properties, soil enzyme activities, heavy metal concentrations, and bacterial diversity near a secondary lead plant in Xuzhou, China were examined in this study. The results showed that secondary lead smelting activities influenced nearby soils. Soil acidification decreased one order of magnitude, with a mean value of 7.3. Soil organic matter also showed a downward trend, while potassium and nitrogen appeared to accumulate. Soil urease and protease activity increased in samples with greater heavy metal pollution, but overall the soil microbial biodiversity decreased. Soil heavy metal concentration-especially Pb and Cd-greatly exceeded the concentrations of Chinese Environmental Quality Standard for Soils (GB 15618-1995). Some environmental factors-such as pH, organic matter, enzyme activity, and the concentration of heavy metals-significantly affected bacterial diversity: compared with the control site, the Chao1 estimator decreased about 50%, while the Shannon diversity index dropped approximately 20%. Moreover, some genera have significant relationships with heavy metal concentration-such as Ramlibacter with Zn and Steroidobacter with Cd-which might act as bio-indicators for soil remediation. These results will provide a new insight in the future for reclaiming soil contaminants caused by secondary lead smelting.

Mathematical Model for Forecasting the Influence of Atmospheric Pollution on Population Morbidity in Stara Zagora Municipality (Bulgaria)

AIM:

This paper aims to create a mathematical model for forecasting the morbidity of the population in the Republic of Bulgaria and the Stara Zagora Municipality in particular as a consequence of the atmospheric pollution.

SUBJECTS AND METHODS:

This model is based on a formula which determines the correlation between the average annual concentrations of atmospheric pollutants SO₂, PM₁₀, Pb aerosols, NO₂ and H₂S) and the morbidity of the population based on the number of people who visited their GPs in a relation with a chronic health problem or emergency condition and the number of hospitalisations in two age groups (newborn to 17 years olds and 18 and older) as well as for the entire population in the period 2009-2013, making it possible to predict morbidity levels.

RESULTS:

The expected morbidity level predictions based on the number of people who visited their GPs in Municipality are lower, while hospitalisation level predictions are higher. This model has been created and tested and is applicable in all residential areas.

CONCLUSIONS:

A new, very sensitive, mathematical model has been created and tested (average margin of error from 0.61% to 2.59%) and is applicable in all residential areas.

An Emission-Free Vacuum Chlorinating Process for Simultaneous Sulfur Fixation and Lead Recovery from Spent Lead-Acid Batteries

Spent lead-acid battery recycling by using conventional technologies is usually accompanied by releases of lead-containing wastewater as well as emissions of sulfur oxides and lead particulates that may potentially cause secondary pollution. This study developed a vacuum chlorinating process for simultaneous sulfur fixation and high-purity lead chloride (PbCl₂) recovery from spent lead paste by using calcium chloride (CaCl₂) and silicon dioxide (SiO₂) as reagents. The process train includes pretreatment, simultaneous PbCl₂ production and sulfur fixation, and PbCl₂ volatilization. The pretreatment eliminated chlorine emission from direct chlorinating reaction of PbO₂ in the initial S-paste (PbSO₄/PbO₂/PbO/Pb). During the subsequent PbCl₂ production and sulfur fixation step, lead compounds in the P-paste (PbSO₄/PbO) was converted to volatile PbCl₂, and sulfur was simultaneously fixed to the solid residues in the form of CaSO₄ to eliminate the emission of sulfur oxides. The final step, PbCl₂ volatilization under vacuum, is a physical phase-transformation process of ionic crystals, following a zeroth-order kinetic model. A cost estimate indicates a profit of USD $ 8.50/kg PbCl₂. This process offers a novel green lead recovery alternative for spent lead-acid batteries with environmental and economic benefits.

Reusable resistive aptasensor for Pb(II) based on the Pb(II)-induced despiralization of a DNA duplex and formation of a G-quadruplex

The article describes a reusable biosensor for Pb(II) ions. A duplex DNA with a terminal amino group and containing a G-quadruplex (G4) aptamer was covalently conjugated to single walled carbon nanotubes on a field effect transistor (FET). The detection scheme is based on the despiralization of the DNA duplex because Pb(II) can induce the G4 aptamer to form a stabilizing G4/Pb(II) complex. This structural change affects the electrical conductivity of SWNTs which serves as the analytical signal. The biosensor was characterized via scanning electron microscopy, Raman, UV-vis, and voltage-current profiles. Under optimized conditions, the relative resistance at 0.02 V increases linearly with the logarithm of the Pb(II) concentration in the range from 1 ng·L^-1 to 100 μg·L^-1, and the limit of detection is 0.39 ng·L^-1. Compared to other sensors, this oner demonstrates superior simplicity, sensitivity, and selectivity even in mixtures of heavy metal ions. It was applied to the determination of Pb(II) in (spiked) water and soil samples and gave good results. Graphical abstract Schematic of the fabrication a biosensor for Pb(II). It is making use of an SWNT-based FET, G4-DNA and complementary DNA with an amino group. Pb(II) can despiralize the DNA duplex to form a G-quadruplex which affects the electrical conductivity of SWNTs. After each detection, the single complementary strand DNA can rebind the G4-DNA, which makes the biosensor reusable.

Sources, symptoms and characteristics of childhood lead poisoning: experience from a lead specialty clinic in China

OBJECTIVES

This study explored the sources of lead exposure, identified patients' geographic distribution and evaluated the symptoms of children with elevated blood lead levels (BLLs) referred to a pediatric lead specialty clinic in China.

MATERIAL AND METHODS

Data were collected from 515 consecutive outpatients attending the Pediatric Lead Poisoning Clinic in Xinhua Hospital, Shanghai, China, between 2011 and 2016, referred for BLLs ≥5 μg/dL. Atomic absorption spectrometry was used to measure venous BLLs.

RESULTS

The mean ± standard deviation age of the patients was 4.1 ± 3.2 years. Their BLLs ranged from 5 to 126 μg/dL. The geometric mean and median BLLs were 24 and 26 μg/dL, respectively. Two hundred and twenty-two children (43.1%) were exposed to industrial lead pollution-mainly from Zhejiang, Jiangsu, Hunan, Henan and Anhui provinces; whereas, 41.4% (213 cases) were induced by folk medicines used widely throughout China. Other nonindustrial sources of lead exposure included lead-containing tinfoil and tin pots. Household lead paint was a rare source. Most patients exhibited nonspecific symptoms, such as hyperactivity, attention difficulty, aggressiveness, constipation and anorexia.

CONCLUSIONS

Industrial pollution and folk medicines are important sources of lead exposure in China. Childhood lead poisoning may be difficult to diagnose clinically as symptoms are nonspecific. Thus, blood lead screening may be necessary to identify children at high risk of exposure. Education to raise the awareness of potential sources of exposure resulting in their elimination would be expected to decrease the incidence of children with elevated BLLs.

Anion exchange coupled with the reduction and dimerisation of a copper(ii) nitrate complex of tripyridyl dithioether via a single-crystal-to-single-crystal transformation

It is a challenge to develop methodologies involving multiple transformations for preparing new materials that cannot be obtained via direct synthesis. Herein, we report an anion exchange process accompanying cation reduction and dimerisation via a single-crystal-to-single-crystal transformation. First, a direct reaction of the flexible tripyridyl dithioether ligand L with CuI afforded a mixture of four bis(ligand) complexes (1a-1d). To avoid the formation of undesired mixed products, a copper(ii) nitrate complex-mediated approach involving anion exchange and cation reduction was employed to generate a monomeric complex, [CuII(L)NO3]NO3·toluene (2). When the dark blue crystals of 2 were immersed in an aqueous NaI solution, the crystals were transformed to a pale yellow dimeric copper(i) iodide complex, [(μ-CuI2I2)(L)2] (3). The observed anion exchange promotes the reduction of copper(ii) to copper(i) at the expense of I-/I3- oxidation as well as dimerisation via the formation of a Cu2I2 cluster. This result corresponds to the synthesis of a compound that otherwise was not able to be prepared via a direct synthetic procedure.

Temporal and spatial characteristics of lead emissions from the lead-acid battery manufacturing industry in China

An inventory of lead emissions was established for the lead-acid battery (LAB) manufacturing industry in China from 2000 to 2014. The lead emissions from the LAB manufacturing industry increased from 133 t in 2000 to a peak at 281 t in 2010 with the rapid development of LAB industry. Since 2011, a mandatory national clean action on LAB industry and a series of retrofitting measures have been implemented in China. As a result, more than 80% of small and low-efficient LAB manufacturers were closed, and technical-environmental performance of the industry has been improved significantly. Thus the lead emissions from the industry declined to 113 t in 2014. Geographically, lead emissions were attributed to several provinces with intensive LAB manufacturers, including Zhejiang, Guangdong, Jiangsu, Shandong, and Hebei Province. Spatial transfer of the LAB manufacturing industry from developed areas to developing areas in China was manifest due to strict environmental regulation, posing potential environmental risks to the areas undertaking the industry transfer. In light of the effectiveness of the national clean action, the LAB manufacturing industry will reduce lead emissions further by implementing the entry criteria strictly, adopting policy of total lead emissions control, and establishing a long-term regulatory mechanism for LAB manufacturers. The local authorities in some developing areas should improve abilities of environmental supervision and environmental risk prevention to deal with the spillover of lead emissions.

Using a novel adsorbent macrocyclic compound cucurbit[8]uril for Pb2+ removal from aqueous solution

In this study, cucurbit[8]uril (CB[8]) was utilized as a kind of new adsorbent to remove Pb²⁺ ions from aqueous solution. With the solution pH increased from 2 to 6, the removal efficiency of adsorption increased from 55.6% to 74.5%correspondingly. The uptake of Pb²⁺ increased rapidly in the initial 30min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily; and the rate determining step in Pb²⁺ adsorption onto CB[8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fitting result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67mg/g for 298K, 149.70mg/g for 313K and 136.42mg/g for 323K, respectively. The adsorption is a spontaneous process of exothermic nature. The effect of the adsorbent dosage and the influences of solution pH and co-existing cations were also investigated. The CB[8] was synthesized and characterized by ¹H NMR, IR, ESI-MS spectra, SEM-EDAX, Zeta-potential and BET-analysis. The adsorption mechanism was due to the coordination between CB[8] molecule and Pb²⁺ ions.

Uncovering the Evolution of Lead In-Use Stocks in Lead-Acid Batteries and the Impact on Future Lead Metabolism in China

This study aims to illustrate the evolution of lead in-use stocks, particularly in lead-acid batteries (LABs), and their impact on future lead metabolism in China. First, we used a bottom-up methodology to study the evolution of lead in-use stocks in China from 2000 to 2014. It was found that the lead in-use stocks increased from 0.91 to 7.75 Mt. The principal driving force of such change is the rapid development of LABs-driven electric vehicles. Then, we proposed three scenarios, low, baseline, and high in-use stocks, to project the lead demand and supply toward 2030. The results show that the LAB demand will decrease as a result of competition and replacement by lithium ion batteries. The lead demand in China will come to a peak around 2018-2020 under the three scenarios, then reduce to 3.7, 4.6, and 5.3 Mt/yr in 2030. Meanwhile, primary lead outputs will follow the increase of zinc production in China. Secondary lead recovered from spent LABs will also increase gradually. The overall unused lead stocks in 2030 will be 49.6, 44.8, and 41.2 Mt under the three scenarios, some 3.5-5.7 times as big as the lead in-use stocks. Thus, a large amount of lead will have to be safely stockpiled or exported in China.

Effectiveness of interventions to reduce exposure to lead through consumer products and drinking water: A systematic review

OBJECTIVES

The objective of this systematic review is to assess the effectiveness of regulatory, environmental and educational interventions for reducing blood lead levels (BLLs) and associated health outcomes in children, pregnant women and the general population.

METHODS

Searches were run in MEDLINE, EMBASE and the Global Health Library up until August 2015. Studies were eligible for inclusion if they assessed the impact of regulatory, environmental or educational interventions, stand-alone or in combination, on BLLs among children, pregnant women or the general population through randomized controlled trials (RCT), controlled before-after (CBA), interrupted time series (ITS), uncontrolled before-after (UBA) or repeated cross-sectional studies. Studies assessing the impact of interventions to reduce exposure to lead in paint or household dust as well as studies concerned exclusively with environmental concentrations of lead were not included. As documented in a detailed protocol, screening, data extraction and quality appraisal were largely undertaken according to Cochrane standards. Harvest plots were used to graphically summarize evidence of effectiveness.

RESULTS

The searches yielded 6466 unique records, of which five met our eligibility criteria; two additional eligible studies were identified by experts. We did not find any studies regarding the effectiveness of regulatory, educational or environmental interventions targeting exposure to lead in consumer products. Evidence regarding the effectiveness of interventions in reducing BLLs from exposures through drinking water is limited in both quantity and quality. Stand-alone targeted educational interventions showed no statistically significant reductions in children's BLL (two RCT) when compared to general educational interventions. Likewise, instructing women to reduce or eliminate lead-contaminated drinking water showed no effect on BLL (one RCT). Stand-alone environmental interventions appeared more promising in reducing BLL (three UBA). Combining educational and environmental interventions and targeting multiple settings may be effective in reducing BLL, as suggested by one uncontrolled before-after study. No studies examining the effectiveness of regulatory interventions were found.

CONCLUSIONS

The limited quantity and quality of the evidence measuring BLL and associated health outcomes points to an urgent need for more robust research into the effectiveness of interventions to reduce lead exposure from consumer products and drinking water, especially for regulatory interventions.

Application of IEUBK model in lead risk assessment of children aged 61-84 months old in central China

Few studies have focused on the accuracy of using the Integrated Exposure Uptake Biokinetic (IEUBK) model in Chinese children with site- and age-specific exposure data. This study aimed to validate the accuracy and sensitivity of the IEUBK model in lead risk assessment of Chinese children aged 61-84 months old. A total of 760 children were enrolled from two respective counties in Central China by using random cluster sampling method. Blood lead levels (BLLs) of all subjects were determined using graphite furnace atomic absorption spectrometry, as well as that in the environmental media, such as air, drinking water, soil, dust and food. Age- and site-specific time-activity patterns and water consumption were evaluated by using questionnaires for children. Exposure parameters including outdoor and indoor activity time, ventilation rate and water consumption in this study were different from the default values of the IEUBK model. Statistical analysis revealed no significant differences between the predicted and observed BLLs. Diet and soil/dust lead intake contributed approximately 83.39% (57.40%-93.84% range) and 15.18% (3.25%-41.60% range) of total lead intake, respectively. These findings showed that the IEUBK model is suitable for lead risk assessment of Chinese children aged 61-84 months old and diet acts as an important lead source.

Childhood lead exposure in an industrial town in China: coupling stable isotope ratios with bioaccessible lead

Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL(-1), averaging 6.1 ± 3.2 μg dL(-1) (mean ± standard deviation), and were ∼1.6 times the national average in China (3.9 ± 1.8 μg dL(-1)). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg(-1)) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)(-1)] contained elevated Pb concentrations. The isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations.