Lead exposure is associated with risk of impaired coagulation in preschool children from an e-waste recycling area

E-waste: mechanisms of toxicity and safety testing

Currently, information on the toxicity profile of the majority of the identified e-waste chemicals, while extensive and growing, is admittedly fragmentary, particularly at the cellular and molecular levels. Furthermore, the toxicity of the chemical mixtures likely to be encountered by humans during and after informal e-waste recycling, as well as their underlying mechanisms of action, is largely unknown. This review paper summarizes state-of-the-art knowledge of the potential underlying toxicity mechanisms associated with e-waste exposures, with a focus on toxic responses connected to specific organs, organ systems, and overall effects on the organism. To overcome the complexities associated with assessing the possible adverse outcomes from exposure to chemicals, a growing number of new approach methodologies have emerged in recent years, with the long-term objective of providing a human-based and animal-free system that is scientifically superior to animal testing, more effective, and acceptable. This encompasses a variety of techniques, typically regarded as alternative approaches for determining chemical-induced toxicities and holds greater promise for a better understanding of key events in the metabolic pathways that mediate known adverse health outcomes in e-waste exposure scenarios. This is crucial to establishing accurate scientific knowledge on mixed e-waste chemical exposures in shorter time frames and with greater efficacy, as well as supporting the need for safe management of hazardous chemicals. The present review paper discusses important gaps in knowledge and shows promising directions for mechanistically anchored effect-based monitoring strategies that will contribute to the advancement of the methods currently used in characterizing and monitoring e-waste-impacted ecosystems.

Process intensification for sustainable extraction of metals from e-waste: challenges and opportunities

The electrical and electronic waste is expected to increase up to 74.7 million metric tons by 2030 due to the unparalleled replacement rate of electronic devices, depleting the conventional sources of valuable metals such as rare earth elements, platinum group metals, Co, Sb, Mo, Li, Ni, Cu, Ag, Sn, Au, and Cr. Most of the current techniques for recycling, recovering, and disposing of e-waste are inappropriate and therefore contaminate the land, air, and water due to the release of hazardous compounds into the environment. Hydrometallurgy and pyrometallurgy are two such conventional methods used extensively for metal recovery from waste electrical and electronic equipment (WEEE). However, environmental repercussions and higher energy requirements are the key drawbacks that prevent their widespread application. Thus, to ensure the environment and elemental sustainability, novel processes and technologies must be developed for e-waste management with enhanced recovery and reuse of the valued elements. Therefore, the goal of the current work is to examine the batch and continuous processes of metal extraction from e-waste. In addition to the conventional devices, microfluidic devices have been also analyzed for microflow metal extraction. In microfluidic devices, it has been observed that the large specific surface area and short diffusion distance of microfluidic devices are advantageous for the efficient extraction of metals. Additionally, cutting-edge technologies have been proposed to enhance the recovery, reusability, and recycling of e-waste. The current study may support decision-making by researchers in deciding the direction of future research and moving toward sustainable development.

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.

Association between urinary multiple metals and platelet-related parameters: A cross-sectional study in a metal-contaminated area of China

Previous works have shown that hematological system can be affected by exposure to lead; however, the effects of multiple metals on platelets remain elusive within the population from metal-contaminated areas. Hence, the study enrolled 609 participants, with 396 from a metal-exposed area and 213 from a control area. Platelet count (PLT), mean platelet volume (MPV), thrombocytocrit (PCT), platelet to large cell ratio (P-LCR), and platelet distribution width (PDW) were selected to evaluate platelet function. Stepwise regression and Lasso regression were utilized to identify the most influential metals. Moreover, the generalized linear model (GLM), Bayesian kernel machine regression (BKMR) models, and quantile g-computation were employed to estimate the individual or combined effects associations between 12 urinary metals and platelet indices. The results revealed all metals except vanadium, copper, strontium, and molybdenum were significantly higher in the exposed group. The GLM models indicated that urinary metals, including lead, antimony, and arsenic, exhibited associations with PLT, MPV, P-LCR, and PDW. Quantile g-computation and BKMR demonstrated negative correlations between metal mixtures and MPV as well as PDW. In conclusion, the study highlights the associations between multiple metal exposures and platelet indices, suggesting that elevated levels of the metal mixture may impede platelet activation in the population in metal-contaminated areas.

Chronic exposure to electronic waste poses risk to liver toxicity with molecular interaction of GSTM1, GSTT1 null variants, and GSTP1

Chronic exposure to electronic waste (e-waste) is becoming a serious concern for health among individuals exposed to it. E-waste has been reported to contain heavy metals, trace elements, and persistent organic pollutants which can trigger health issues through different biological pathways. The liver is a major metabolic and detoxifying organ in the body. Glutathione S-transferase (GST) is a liver enzyme for phase II detoxification that catalyzes glutathione (GSH) conjugation with environmental pollutants. This research aimed to investigate the liver toxicity caused by long-term exposure to e-wastes, exploring the potential association with null variants of GSTT1 and GSTMI, as well as GSTP1. The study was designed as a cross-sectional investigation, in which 256 adult males who were chronically exposed to e-waste and 200 non-exposed control participants, matched for age and gender, were recruited randomly. Standard colorimetric and enzymatic methods were used to analyze biochemical parameters such as serum alkaline phosphatase (ALP), alanine transaminase (ALT), total bilirubin (T. Bil), albumin, and reduced glutathione. Genotypic analysis of the null variant GSTM1, GSTT1, and GSTP1 genes was conducted by standard molecular methods. The study findings indicated a notable surge in ALP, ALT, and albumin levels while T. Bil and GSH levels showed a reduction, suggesting a potential risk of liver toxicity. Additionally, analysis of GSTM1, GSTT1, and GSTP1 genotypes revealed a possible association with GSH levels and the hepatotoxicity risk. The study concluded that the individuals exposed to e-waste exhibited dysregulation of liver enzymes that results in liver toxicity. Moreover, analysis of GSTM1, GSTT1, and GSTP1 at a molecular level revealed that these genes could potentially serve as risk factors for liver toxicity in e-waste chronic exposure.

A review of various strategies in e-waste management in line with circular economics

Waste management of electrical and electronic equipment has become a key challenge for electronics manufacturers due to globalization and the rapid expansion of information technology. As the volume of e-waste grows, legal departments lack the infrastructure, technology, and ability to collect and manage it environmentally soundly. Government laws, economic reasons, and social issues are important considerations in e-waste management. The circular economy concept is built on reusing and recycling goods and resources. A novel idea called the circular economy might prevent the negative consequences brought on by the exploitation and processing of natural resources while also having good effects such as lowering the demand for raw materials, cutting down on the use of fundamental resources, and creating jobs. To demonstrate the significance of policy implementation, the necessity for technology, and the need for societal awareness to build a sustainable and circular economy, the study intends to showcase international best practices in e-waste management. This study uses circular economy participatory implementation methods to provide a variety of possible approaches to assist decision-makers in e-waste management. The purpose of this article is to review the most accepted methods for e-waste management to emphasize the importance of implementing policies, technology requirements, and social awareness in creating a circular economy. To conclude, this paper highlights the necessity of a common legal framework, reform of the informal sector, the responsibility of different stakeholders, and entrepreneurial perspectives.

Blood lead levels of children exposed to e-waste: a systematic review and meta-analysis

Blood lead levels (BLLs) have been decreasing worldwide for decades. However, systematic reviews and quantitative syntheses of BLLs in electronic waste (e-waste)-exposed children are lacking. To summarize temporal trend of BLLs among children in e-waste-recycling areas. Fifty-one studies met the inclusion criteria and included participants from six countries. Meta-analysis was performed using the random-effects model. Results showed that among e-waste-exposed children, the total geometric mean (GM) BLL was 7.54 μg/dL (95% CI: 6.77, 8.31). Children's BLLs displayed a decreasing temporal trend, from 11.77 μg/dL in phase I (2004-2006) to 4.63 μg/dL in phase V (2016-2018). Almost 95% of eligible studies found that children exposed to e-waste had significantly higher BLLs than reference groups. The difference of children's BLLs between the exposure group and the reference group was from 6.60 μg/dL (95% CI: 6.14, 7.05) in 2004 to 1.99 μg/dL (95% CI: 1.61, 2.36) in 2018. For subgroup analyses, except for Dhaka and Montevideo, the BLLs of children from Guiyu in the same survey year were higher than those of children from other regions. Our findings indicate that the gap between BLLs of children exposed to e-waste and those of reference group children is closing, and we appeal that the critical value for blood lead poisoning in children should be lowered in key e-waste-dismantling areas of developing countries, such as Guiyu.

A systematic review of the health effects of lead exposure from electronic waste in children

Introduction

Electronic waste (e-waste) is an emerging human and environmental problem. Lead (Pb) is one of the most dangerous chemicals for human health, and it is the most prevalent heavy metal pollutant in e-waste. Despite the rapid growth of e-waste globally and the health effects of Pb, there is little information regarding the effects of Pb exposure from e-waste on children. Therefore, the aim of this review was to provide concise information on the health effects of Pb exposure from e-waste on children.

Methods

A comprehensive search of databases was undertaken using PubMed/MEDLINE, Cochrane Library, Science Direct, HINARI, African Journal Online (AJOL), and additional sources were searched up to November 25, 2022. Eligibility criteria were determined using Population, Exposure, Comparator, and Outcome (PECO). The guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) were used during the article selection process. The protocol of this systematic review was registered in the International Prospective Register of Systematic Reviews (Registration ID: CRD42022377028). The Joanna Briggs Institute (JBI) quality appraisal checklist was used to assess the quality of the included studies.

Results

From a total of 1,150 identified studies, 20 full-text studies were included in the systematic review. All most included studies were conducted in China recycling area for e-waste. The included studies were conducted with an exposed group versus a reference group. The majority of the included studies found that blood Pb levels were ≥5 μg/dl and that Pb exposures from e-waste were affecting children's health, such as a decrease in serum cortisol levels, inhibition of hemoglobin synthesis, impact on neurobehavioral development, affect physical development, etc.

Conclusion

Lead exposure had a significant impact on children's health as a result of informal e-waste recycling. Therefore, formalizing the informal sector and raising public health awareness are important steps toward reducing Pb exposure from e-waste. Moreover, the concerned stakeholders, like national and international organizations, should work together to effectively manage e-waste.

Kindergarten indoor dust metal(loid) exposure associates with elevated risk of anemia in children

Exposure to metals and metalloids in indoor dust is associated with adverse health effects in young children, but there is limited evidence for an association with anemia, which is at high risk in children. The aim of this study was to investigate the association between exposure to multiple metal(loid)s in indoor dust in kindergartens and the risk of anemia in children. In 2021, 2165 children from 25 kindergartens in eastern China were included in the study and had their hemoglobin (Hb) measured. Indoor dust samples were collected from the children's kindergartens, and the concentrations of 11 metals and metalloids in the samples were measured using inductively coupled plasma mass spectrometry (ICP-MS). The daily exposure dose (DED) of dust was used to assess the risk of metal(loid) exposure in the children. The results showed that of the 2165 children with available data, 351 (16.2 %) met the WHO definition of anemia. In multiple linear regression and logistic regression analyses, we found that for each quartile of DED increase in Cd inhalation, child Hb levels decreased by 2.703 g/L (95 % CI: -4.055, -1.351), and the risk of anemia increased 1.602-fold (95 % CI: 1.087, 2.360). Mn ingestion was associated with increased odds of anemia [odds ratio (OR) = 1.760 (95 % CI: 1.217, 2.544)]. Interaction analysis indicated that metal(loid)s exposure effects were modified by child sex, age, and body mass index (BMI). Cluster analysis found that children at high risk of metal(loid) exposure in the school environment tended to have lower Hb levels and higher prevalence of anemia compared with those at low risk, although this was not statistically significant. These findings suggest that child school exposure to metal(loid)s in indoor dust is associated with an increased risk of developing anemia in children, modified by child sex, age, and BMI.

Assessment for the associations of twenty-three metal(loid)s exposures with early cardiovascular damage among Chinese urban adults with five statistical methods: Insight into assessing health effect of multipollutant exposure

The topic of cardiovascular hazards from multiple metal (loid)s exposures has attracted widespread attention. Here, we measured concentrations of twenty-three urinary metal (loid)s and mean platelet volume (MPV), an early cardiovascular damage biomarker, for 3396 Chinese adults. We aimed to comprehensively assess the associations of single metal (loid) and multiple metal (loid)s (as a mixture) with MPV by combined use of five statistical methods, including general linear models, Bayesian kernel machine regression (BKMR), weight quartile sum (WQS) regression, quantile g-computation (QGC), and adaptive elastic network regression (AENR). And based on that, we hope to provide insight into assessing the health effect of multipollutant exposure. After adjustment for potential covariates, at least three methods jointly suggested that of twenty-three metal (loid)s, iron, arsenic, and antimony were positively while aluminum, tungsten, and thallium were inversely associated with MPV. The environmental risk score of metal (loid)s construed by AENR was significantly positively associated with MPV, while the association between overall twenty-three metal (loid)s mixture and MPV was neutralized to be insignificant in QGC and BKMR. Conclusively, single metal (loid) may be inversely (iron, arsenic, and antimony) and positively (aluminum, tungsten, and thallium) associated with early cardiovascular damage, while the association of overall twenty-three metal (loid)s mixture with MPV was insignificant when concurrent exposures exist. It is crucial to select appropriate statistical methods based on study purpose and principles/characteristics of statistical methods, and combined employment of multimethod is insightfully suggested when assessing health effects of multipollutant exposure.

Biochemical and Hematological Markers in Workers with Chronical Exposure to Lead and Cadmium in Colombia

The aim of the present study was to find if workers chronically exposed to lead (Pb) and cadmium (Cd) presented changes in their general health and in the clinical parameters of the population under study. We carried out a cross-sectional survey in a sample of informal workers in Cartagena, Colombia. The population under study was composed of male informal workers (≥18 years of age), with experience in their job, selected from occupational settings with potential exposure to Pb and Cd (i.e., mechanics, battery and garbage recyclers, and welders). The median age was 45 years (interquartile range (IQR), 33−53). The median blood Pb level (BLL) was 2 μg/dL (IQR, 0.76−6.22), and the median of blood Cd level (BCL) was 1.22 μg/L (IQR, 0.33−2.01). The study found that 33% of high exposure jobs with BLL > 5 μg/dL (n = 57), whereas in ‘control’ workers, this was 15.3% (n = 9). The highest BLLs were found in battery recyclers (82.1%; n = 23), followed by mechanics (37.3%, n = 22). In the logistic regression model adjusted by age, time on the job, smoking and elevated BCL and BLL increased 3.2 times (95% CI, 1.1−9.7) in mechanics and 29.6 times (95% CI, 7.2−145.6) in battery recyclers. This study found negative changes in the health of workers with higher chronic exposure to lead in Cartagena, Colombia.

Pb and Cd exposure linked with Il-10 and Il-13 gene polymorphisms in asthma risk relevant immunomodulation in children

Genetic variants and environmental factor of heavy metal exposure accelerate the risk of immune-mediated respiratory diseases, including asthma in children. This study aims to investigate the effects and interaction of Pb, Cd exposure from e-waste and interleukin (IL)-10, IL-13 gene polymorphisms on interleukin expressions in children. Pb, Cd levels, Il-10 (rs1800871, rs1800872, rs1800896) and Il-13 (rs20541, rs1800925) polymorphisms were determined in blood or urine of 155 children (75 from e-waste-exposed area, Guiyu and 80 from reference area, Haojiang). Blood Pb and urine Cd levels of e-waste-exposed children were both higher (mean: 5.89 vs. 3.35 μg/dL; 6.04 vs. 1.82 μg/g, both P < 0.05). Exposed children had a larger proportion of high blood Pb level (> 5.00 μg/dL) (66.67% vs. 4.11%, P < 0.001), but they had no statistically different proportion of high urine Cd level (> 1.00 μg/g creatinine). Median levels of IL-13 decreased (3.674 vs. 4.410 ng/L, P < 0.01), but of IL-10 did not vary in serum of exposed children. The analyses revealed no significant associations of Pb or Cd with Il-10 or Il-13 gene polymorphisms. The high blood Pb and urine Cd level were respectively associated with the low IL-13 ( < 3.696 ng/L) and low IL-10 ( < 0.361 ng/L) level, after adjustment for children's age, gender, and BMI (both P ≤ 0.05). Children homozygous carrying major allele for Il-13 (rs20541 and rs1800925) had additive interactions with high blood Pb level on low IL-13 expression (OR = 5.37, 95% CI: 1.96, 14.73 and OR = 8.45, 95% CI: 2.61, 27.32; both P ≤ 0.001). In contrast, no interaction was observed amongst Pb or Cd with Il-10 gene polymorphisms on its expression. Our findings suggest that Pb exposure interacting with Il-13 gene polymorphisms negatively regulates IL-13 expression, which may pose a risk to abnormal asthma-relevant immunomodulation in preschool children.

PM2.5 exposure and pediatric health in e-waste dismantling areas

Fine particulate matter (PM_2.5) is the first leading environmental risk factor for death according to the Global Burden of Disease Study 2019. Children are in a pivotal window stage of growth and development, and one of the most sensitive and vulnerable groups when they are exposed to PM_2.5. E-waste refers to the abandoned electrical or electronic equipment. Informal e-waste dismantling activities, such as heating, burning, and roasting, will release a large number PM_2.5 into the local atmosphere. PM_2.5 exposure levels are higher in e-waste dismantling areas than those in reference areas. PM_2.5 derived from e-waste contains a variety of toxic and harmful components such as transition metals and persistent organic pollutants. Few studies have focused on the exposure levels of PM_2.5 and its compositions in e-waste dismantling areas, but little is known about their effects on children's health. Therefore, this study will briefly summarize the impact of PM_2.5 on children's health in e-waste dismantling areas.

Health consequences of exposure to e-waste: an updated systematic review

Electronic waste (e-waste) contains numerous chemicals harmful to human and ecological health. To update a 2013 review assessing adverse human health consequences of exposure to e-waste, we systematically reviewed studies reporting effects on humans related to e-waste exposure. We searched EMBASE, PsycNET, Web of Science, CINAHL, and PubMed for articles published between Dec 18, 2012, and Jan 28, 2020, restricting our search to publications in English. Of the 5645 records identified, we included 70 studies that met the preset criteria. People living in e-waste exposed regions had significantly elevated levels of heavy metals and persistent organic pollutants. Children and pregnant women were especially susceptible during the critical periods of exposure that detrimentally affect diverse biological systems and organs. Elevated toxic chemicals negatively impact on neonatal growth indices and hormone level alterations in e-waste exposed populations. We recorded possible connections between chronic exposure to e-waste and DNA lesions, telomere attrition, inhibited vaccine responsiveness, elevated oxidative stress, and altered immune function. The existence of various toxic chemicals in e-waste recycling areas impose plausible adverse health outcomes. Novel cost-effective methods for safe recycling operations need to be employed in e-waste sites to ensure the health and safety of vulnerable populations.

Human Body Burden of Heavy Metals and Health Consequences of Pb Exposure in Guiyu, an E-Waste Recycling Town in China

Guiyu accommodates millions of tons of e-waste from overseas and domestic sources each year and is notorious for its e-waste dismantling industry. As a consequence, Guiyu has been described as "the world's most toxic place" and "junk town". Informal e-waste recycling activities have caused severe pollution to the local environment and are associated with extensive health problems to the residents. This review provides updated insights on the body burden of heavy metals derived from e-waste and health outcomes resulted from lead (Pb) exposure. The review identified that Guiyu has been highly contaminated by heavy metals, especially Pb. Excessive exposure to Pb has been associated with multi-system and long-term effects in neonates and children, covering nervous, cardiovascular, adaptive immune, and hematologic systems as well as chromosome and DNA damage. Our review indicates strong associations that emphasize the need to develop strong regulations for prevention of exposure and health consequences in Guiyu and similar sites around the world.

E-waste polycyclic aromatic hydrocarbon (PAH) exposure leads to child gut-mucosal inflammation and adaptive immune response

Polycyclic aromatic hydrocarbon (PAH) exposure alters immunological responses. Research concerning PAH exposure on intestinal immunity of children in electronic waste (e-waste) areas is scarce. The aim of this study was to evaluate the effects of polycyclic aromatic hydrocarbon (PAH) pollutants on intestinal mucosal immunity of children in e-waste areas. Results showed higher hydroxylated PAH (OH-PAH) concentrations in e-waste-exposed children, accompanied with higher sialyl Lewis A (SLA) level, absolute lymphocyte and monocyte counts, decreased of percentage of CD4⁺ T cells, and had a higher risk of diarrhea. OH-PAH concentrations were negative with child growth. 1-OHNap mediated through WBCs, along with 1-OHPyr, was correlated with an increase SLA concentration. 2-OHFlu, 1-OHPhe, 2-OHPhe, 1-OHPyr, and 6-OHChr were positively correlated with secretory immunoglobulin A (sIgA) concentration. Our results indicated that PAH pollutants caused inflammation, affected the intestinal epithelium, and led to transformation of microfold cell (M cell). M cells initiating mucosal immune responses and the subsequent increasing sIgA production might be an adaptive immune respond of children in the e-waste areas. To our knowledge, this is the first study of PAH exposure on children intestinal immunity in e-waste area, showing that PAH exposure plays a negative role in child growth and impairs the intestinal immune function.

Bibliometric analysis of studies involving e-waste: a critical review

The correct destination of waste is an essential factor for sustainable development. Electronic waste, which is very toxic, is the type of waste with the highest rate of increase in its generation. For these reasons, the amount of research on this topic increases year by year, as shown by the literature review carried out by this study. This review aims to identify the main characteristics and proposals of the main study on electronic waste and verify how Brazil is inserted globally in the research on e-waste. Another objective is to suggest a path for researchers who want to start research on e-waste by identifying the keywords most used in the analyzed articles. The results evidenced that the most published countries on the subject are China, the USA, and India. Brazil is in a position of little prominence concerning its research production on the subject. Most of the central studies we analyzed use case study and literature review as the research method. Among the 44 articles analyzed, only one proposed a destination for e-waste. It highlights the need for more research focusing on the environmentally correct destination of e-waste. A good way to start a search on electronic waste is to use the keywords identified in this study, especially those used most frequently in the analyzed articles.

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.

Low-level Eexposure to lead dust in unusual work schedules and hematologic, renal, and hepatic parameters

BACKGROUND

Many workers are exposed to lead dust in lead-‑zinc mines. Exposure to this heavy toxic metal and its compounds can cause irreversible adverse health effects.

OBJECTIVE

To assess possible hematotoxic, nephrotoxic, and hepatotoxic potentials of low levels of lead in a group of mine workers exposed to this heavy metal in an unusual work schedule.

METHODS

A total of 73 exposed and 70 non-exposed employees were interviewed. Demographic data, and occupational and medical history of the employees were obtained by questionnaires. Air monitoring was performed to determine the workers' time-weighted average (TWA) exposure to lead dust. The threshold limit value (TLV) for lead was adjusted for unusual work schedules according to the model developed by the University of Montreal and the Institute de Recherche en Sante et en Securite du Travail (IRSST). Blood samples were collected for complete blood count, liver and kidney function tests. Data were analyzed using version 21.0 of the SPSS software.

RESULTS

The TWA exposure of workers was 24 μg/m³. On average, the worker's exposure to lead dust did not exceed the 8-h OSHA and ACGIH TLV-TWA of 50 μg/m³. Significant associations were found only between exposure to lead and platelet count, red cell distribution width, total protein, and albumin.

CONCLUSIONS

Exposure to low levels of lead dust in unusual work schedules was not associated with overt hematotoxicity, hepatotoxicity or nephrotoxicity. However, mild, sub-clinical, pre-pathologic significant changes were noted in some blood parameters of the exposed employees as compared with their referent counterparts.

D-serine reduces memory impairment and neuronal damage induced by chronic lead exposure

Although exogenous D-serine has been applied as a neural regulatory intervention in many studies, the role played by D-serine in hippocampal injuries caused by lead exposure remains poorly understood. Rat models of chronic lead exposure were established through the administration of 0.05% lead acetate for 8 weeks. Simultaneously, rats were administered 30 or 60 mg/kg D-serine, intraperitoneally, twice a day. Our results showed that D-serine treatment shortened the escape latency from the Morris water maze, increased the number of times that mice crossed the original platform location, and alleviated the pathological damage experienced by hippocampal neurons in response to lead exposure. Although D-serine administration did not increase the expression levels of the N-methyl-D-aspartate receptor subtype 2B (NR2B) in the hippocampi of lead-exposed rats, 60 mg/kg D-serine treatment restored the expression levels of NR2A, which are reduced by lead exposure. These findings suggested that D-serine can alleviate learning and memory impairments induced by lead exposure and that the underlying mechanism is associated with the increased expression of NR2A in the hippocampus. This study was approved by the Animal Ethics Committee of North China University of Science and Technology, China (approval No. LX2018155) on December 21, 2018.

Associations between prenatal and postnatal lead exposure and preschool children humoral and cellular immune responses

Studies have shown that lead exposure affected the immune function, but few studies have examined the relationships between in utero lead exposure, a sensitive period that is important for immune development, and later immune responses. To investigate the effects of prenatal and childhood lead exposure on the preschool-aged children's immune responses, a prospective birth cohort study was established in Wuhan, China, in which lead concentrations were analyzed in maternal urine during the third trimester and in plasma samples from children aged about 3 years. We assessed immune responses by measuring immune cytokines in the children's plasma (n = 326) and peripheral blood T lymphocyte subsets (n = 394) at 3 years of age. Each unit increase in maternal urinary lead concentration (μg/g creatinine) was associated with reduced IL-10 (β = -5.93%, 95%CI: -11.82%, -0.03%) and reduced IL-4 levels (β = -5.62%, 95%CI: -10.44%, -0.80%). Lead in children's plasma (μg/L) was associated with significant increase in TNF-α (β = 10.78%, 95%CI: 3.97%, 17.59%). No statistically significant relationship of childhood lead exposure with T lymphocyte subsets was observed. The study suggested prenatal and childhood lead exposure was associated with changes in preschool children's plasma cytokine levels.

Cellular and Molecular Mechanisms of Environmental Pollutants on Hematopoiesis

Hematopoiesis is a complex and intricate process that aims to replenish blood components in a constant fashion. It is orchestrated mostly by hematopoietic progenitor cells (hematopoietic stem cells (HSCs)) that are capable of self-renewal and differentiation. These cells can originate other cell subtypes that are responsible for maintaining vital functions, mediate innate and adaptive immune responses, provide tissues with oxygen, and control coagulation. Hematopoiesis in adults takes place in the bone marrow, which is endowed with an extensive vasculature conferring an intense flow of cells. A myriad of cell subtypes can be found in the bone marrow at different levels of activation, being also under constant action of an extensive amount of diverse chemical mediators and enzymatic systems. Bone marrow platelets, mature erythrocytes and leukocytes are delivered into the bloodstream readily available to meet body demands. Leukocytes circulate and reach different tissues, returning or not returning to the bloodstream. Senescent leukocytes, specially granulocytes, return to the bone marrow to be phagocytized by macrophages, restarting granulopoiesis. The constant high production and delivery of cells into the bloodstream, alongside the fact that blood cells can also circulate between tissues, makes the hematopoietic system a prime target for toxic agents to act upon, making the understanding of the bone marrow microenvironment vital for both toxicological sciences and risk assessment. Environmental and occupational pollutants, therapeutic molecules, drugs of abuse, and even nutritional status can directly affect progenitor cells at their differentiation and maturation stages, altering behavior and function of blood compounds and resulting in impaired immune responses, anemias, leukemias, and blood coagulation disturbances. This review aims to describe the most recently investigated molecular and cellular toxicity mechanisms of current major environmental pollutants on hematopoiesis in the bone marrow.

E-waste lead exposure and children's health in China

China is one of the countries worldwide confronted with serious e-waste pollution and associated detrimental health effects, which has aroused public, academic and governmental concerns. Most local residents are exposed to hazardous substances such as lead (Pb) and other persistent organic pollutants because of informal e-waste recycling activities. This study reviews recent studies on children exposed to e-waste Pb in China focusing on health-related effects in children (e.g. growth and development, cardiovascular, immune, nervous, respiratory, reproductive, skeletal, and urinary systems) and evaluating the evidence for the association between e-waste Pb exposure and the children health outcomes in China. Children are one of most sensitive and vulnerable groups when facing e-waste Pb exposure. Previous data indicate that exposure to e-waste Pb has adverse effect on human health such as delayed and damaged physical and nervous development. It is the time to take effective measures, such as upgrading e-waste recycling technology, enhancing government policy guidance and support, and strengthening environmental protection and health awareness of the local inhabitants, to prevent the adverse effects of e-waste.

Oral antimicrobial activity weakened in children with electronic waste lead exposure

Environmental lead (Pb) exposure can induce dysbacteriosis, impair oral health, and is associated with the development of dental caries. However, the mechanism is unclear. The aim of this study was to explore the effects of Pb toxicity on oral antimicrobial activity in children in an e-waste area. Results showed higher blood Pb levels in e-waste-exposed group children, accompanied by decreased saliva SAG (salivary agglutinin) concentrations, increased peripheral WBC (white blood cell) counts and monocyte counts, and elevated peripheral monocyte percentage. LnPb (natural logarithmic transformation of blood Pb level) was negatively correlated with saliva SAG concentration, while positively correlated with peripheral monocyte percentage. Saliva SAG concentration played a complete mediating role in the correlation of LnPb to peripheral monocyte percentage. To our knowledge, this is the first study on the relationship of environmental Pb exposure and oral antimicrobial activity in children, showing that environmental Pb exposure may weaken oral antimicrobial activity through reducing saliva SAG concentration, which may raise the risk of oral dysbacteriosis and ultimately pathogen infection.

Dose and duration-dependent toxicological evaluation of lead acetate in chicks

Lead is one of the utmost contaminated and dangerous heavy metals. This toxicant ultimately enters into the human body through the food chain and accumulated in the body because the animal/human body has not an appropriate mechanism to excrete it from the body. The main objective of the present research was to assess the toxicological effects of lead on body weights, biochemical, and hematological parameters of chickens and also to measure its bioaccumulation in the brain. Lead acetate was administrated orally at doses of 0, 71, 142, 213, and 284 mg/kg of body weight of chicken for groups A, B, C, D, and E, respectively. Along with determination of biometry of all experimental chicks, hematological [hemoglobin (Hb), packed cell volume (PCV), mean corpuscular hemoglobin concentration (MCHC), total erythrocyte count (TEC), white blood cells (WBCs), leukocyte differential count (LDC)] and biochemical [low density lipoprotein (LDL), total protein, high-density lipoprotein (HDL), and alanine aminotransferase (ALT)] parameters were measured. The present study showed that the bodyweight of chickens was not affected significantly by lead acetate exposure. The levels of MCHC, PCV, TEC, Hb, LDL, HDL, and total protein were found to be significantly decreased while WBC, LDC, and ALT profile were enhanced due to administration of lead acetate. Bioaccumulation of lead acetate was found to be higher in the brain. We conclude that the chronic administration of lead acetate affected the blood and biochemical profile of exposed chicken. These effects might be due to the accumulation of the chemical in certain vital organ(s). However, further studies in the future are suggested to refine such findings.

Decreased erythrocyte CD44 and CD58 expression link e-waste Pb toxicity to changes in erythrocyte immunity in preschool children

Lead (Pb) toxicity damages blood cells and disturbs the immune micro-environment. When Pb enters the circulatory system, >95% of Pb accumulates in erythrocytes. We therefore conducted this study to explore the long-term effect of Pb exposure on expression of erythrocyte adhesion molecules (CD44 and CD58) and related downstream cytokine concentrations. We enrolled a total of 267 preschool children, 2-7 years of age, from Guiyu (e-waste-exposed group, n = 132) and Haojiang (reference group, n = 135) in November and December 2015. We measured child blood Pb, biomarkers including erythrocyte CD44 and CD58, erythrocyte count, leukocyte count and inflammatory cytokines (IL-1β, IL-12p70 and IFN-γ), and calculated erythrocyte Pb levels. Regression model demonstrated that higher erythrocyte Pb was associated with lower CD44 and CD58. Compared to low erythrocyte Pb levels (quartile 1), high erythrocyte Pb levels (quartile 4) were related to lower levels of erythrocyte CD44 and CD58. Elevated blood Pb correlated with higher IL-12p70 and IFN-γ, and lower IL-2. The mediation effect of erythrocyte CD44 on the relationship of erythrocyte Pb with IL-1β and IL-12p70 was significant, and the effect of erythrocyte Pb on IFN-γ was mediated by erythrocyte CD58. The data provides novel translational insight into the relationship between elevated Pb exposure and the change of erythrocyte immunity and downstream cytokine secretion in preschool children.

Air pollution and body burden of persistent organic pollutants at an electronic waste recycling area of China

This paper reviews the concentrations of persistent organic pollutants (POPs) in atmosphere of an electronic waste (e-waste) recycling town, Guiyu, in Southeast China, focusing on polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). We assess the evidence for the association between air pollution and human body burden, to provide an indication of the severity of respiratory exposure. Compared with standards and available existing data for other areas, it clearly shows that four typical POPs, derived from recycling processes, lead to serious atmospheric pollution and heavy body burden. From published data, the estimated respiratory exposure doses of Guiyu adults and children, varied between 2.48-10.37 and 3.25-13.6 ng kg^-1 body weight (bw) day^-1 for PBDEs, 2.31-7.6 and 4.09-13.58 pg World Health Organization-Toxic Equivalent Quantity (WHO-TEQ) kg^-1 bw day^-1 for PCDD/Fs, 5.57 and 20.52 ng kg^-1 bw day^-1 for PCBs, and 8.59-50.01 and 31.64-184.14 ng kg^-1 bw day^-1 for PAHs, respectively. These results show that air pollution is more harmful to children. Furthermore, except for PBDEs, the hazard quotient (HQ) of the other three pollutants was rated more than 1 by respiratory exposure only, and all of them are at risk of carcinogenesis. So we speculate these pollutants enter the body mainly through air inhalation, making respiratory exposure may be more important than dietary exposure in the Guiyu e-waste recycling area. Effective management policies and remediation techniques are urgently needed to prevent the deterioration of ambient air quality in the e-waste recycling area.