Toxicological effects in children exposed to lead: A cross-sectional study at the Colombian Caribbean coast

DNA damage and ALAD polymorphism in high blood lead (Pb) levels of pregnant women attending a tertiary care teaching hospital

Background

Pregnant women are particularly vulnerable to lead toxicity due to increased absorption and decreased elimination of lead from their bodies. The δ-aminolevulinic acid dehydratase (ALAD) gene plays a crucial role in lead metabolism, and its polymorphisms have been implicated in modifying the susceptibility to lead toxicity.

Methods

A cross-sectional study was conducted involving 90 pregnant women and blood samples were collected to measure blood lead levels (BLL) and assessed DNA damage using the comet assay. ALAD polymorphisms were genotyped using PCR-RFLP analysis with MspI restriction enzyme. Statistical analysis, including chi-square tests, logistic regression, and correlation analysis, was performed to determine associations between ALAD polymorphisms, BLL, and DNA damage.

Results

From 90 pregnant women the participants, 16 had high BLL (≥5 μg/dL), while the remaining 74 had normal levels (<5 μg/dL). The ALAD 1-2 genotype was found to be significantly associated with high BLL (p < 0.001). Pregnant women with the ALAD 1-2 genotype exhibited higher levels of DNA damage compared to those with other genotypes (p < 0.001). Furthermore, a positive correlation was observed between the transfer of lead concentration from mother to infant and DNA damage severity (r = 0.511, p < 0.001).

Conclusions

The combination of comet assay and polymorphism analysis offers a comprehensive approach to understanding the impact of lead exposure during pregnancy. These findings underscore the urgent need for effective regulatory measures to reduce lead exposure in the environment and mitigate its adverse effects of lead on maternal and child health.

An innovative aluminium foil electrode modified with Al nanoparticles and EDTA for lead detection in biological samples

This study presents a novel Aluminium foil-based electrode characterized by its affordability, flexibility, and ease of modification with carboxylic moiety-containing organic molecules. Upon foil modification with Aluminium nanoparticles and EDTA (AlNP-EDTA/AlE), the modified electrode exhibits remarkable activity in the oxidation of lead at potentials around -0.4 V. The lead signal is derived from the oxidation of lead deposited on the electrode surface using anodic stripping voltammetry (ASV). The addition of EDTA to AlNP/AlE increased the anodic peak current of lead by more than 500 %. The surface characterization of the electrode was performed by scanning electron microscopy (SEM) and infrared spectroscopy (IR), while its electroactive properties were evaluated by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Optimal operating parameters include pH 2.1, square-wave voltammetry (SWV) with an accumulation time of 60 s and an accumulation potential of -0.8 V. A low detection limit of 0.20 µmol/L and a relative standard deviation (RSD) of 3.0 % were achieved using five different electrodes. The effectiveness of AlNP-EDTA/AlE was further demonstrated with consistent results in biological samples spiked with Pb.

Co-exposure to Aluminium and Cadmium Mediates Postpartum Maternal Variation in Brain Architecture and Behaviour of Mice; Involvement of Oxido-nitrergic and Cholinergic Mechanisms : Postpartum effects of Aluminium and Cadmium co-exposure in pregnancy

Most research has not been done on the possible relationship between pregnant women's cross-metal exposures and postpartum neuroendocrine functions. The purpose of this study was to look into how co-exposure to aluminium chloride (AlCl3) and cadmium chloride (CdCl2) affected the neuroendocrine and neurometabolic changes in postpartum mice. A total of 24 adult pregnant female mice were used for the study. Group 1 served as control and received neither AlCl3 nor CdCl2 (n=6), group 2 comprised pregnant mice treated with AlCl3 (10mg/kg), group 3 with CdCl2 (1.5mg/kg), group 4 with a combination of AlCl3 (10 mg/kg) and CdCl2 (1.5 mg/kg).Oral treatment of animals was done daily from gestation day 7 to gestation day 20. Upon delivery and weaning on postnatal day 21 (PND 21), behavioural assessment was done on the postpartum mice and immediately followed by sacrifice for assessment of histological and neuroendocrine markers. Our findings revealed that the brain-to-body weight ratio was affected and brain oxidative stress was elevated in mice exposed to AlCl3 and CdCl2 during pregnancy. Given the strong association between postpartum hyperactivity, social interaction index, brain catalase and acetylcholinesterase activity, and the brain/body weight ratio, it is plausible that these effects have played a role in the adverse behavioural abnormalities observed in the postpartum maternal mice. Moreover, it was noted that in certain situations, co-exposures to the metals tended to have opposite effects to single metal exposures.

Neurodevelopmental assessments used to measure preschoolers' cognitive development in Latin America: a systematic review

OBJECTIVE

The objective of this study was to systematically review the standardized neurodevelopmental assessments used to study preschool-aged children's cognitive development in Spanish-speaking Latin America.

METHODS

The authors systematically searched PubMed, PsycINFO, and ERIC databases for peer-reviewed articles from Spanish-speaking Latin American countries. Articles were included if they measured cognitive development among children aged 2-6 years using at least one standardized assessment tool; 97 articles were included and reviewed in accordance with PRISMA guidelines to assess their use of these tools.

RESULTS

Ninety-seven studies across 13 countries used a total of 41 assessments to measure cognitive development; most widely used were the Wechsler intelligence scales (n = 46/97), particularly the Wechsler Preschool and Primary Scale of Intelligence and Wechsler Intelligence Scale for Children (n = 23 and 29, respectively). Other common assessments included the McCarthy Scales of Children's Abilities (n = 9), Raven's Progressive Matrices (n = 9), Child Neuropsychological Assessment (n = 8), and Peabody Picture Vocabulary Test (n = 7). In regions where normative data for a given assessment were unpublished, authors commonly used norms from the United States, Mexico, or Spain or did not report standard scores in their analyses.

CONCLUSIONS

The wide range of tools used in these studies presents a challenge for generalizing results when measuring the neurodevelopment of Latin American preschool-aged children. The low availability of normative data for specific regions reveals concerns if some tools are culturally and linguistically appropriate even when Spanish is a common language, particularly in low-resource settings. Future work to forge greater consistency in the use of validated measures, clarity in reporting research methods, and publication of regional normative data would benefit the field.

Insight into the effect of a heavy metal mixture on neurological damage in rats through combined serum metabolomic and brain proteomic analyses

The heavy metals lead (Pb), cadmium (Cd), and mercury (Hg) that cause neurocognitive impairment have been extensively studied. These elements typically do not exist alone in the environment; they are often found with other heavy metals and can enter the body through various routes, thereby impacting health. Our previous research showed that low Pb, Cd, and Hg levels cause neurobehavioral impairments in weaning and adult rats. However, little is known about the biomarkers and mechanisms underlying Pb, Cd, and Hg mixture-induced neurological impairments. A combined analysis of metabolomic and proteomic data may reveal heavy metal-induced alterations in metabolic and protein profiles, thereby improving our understanding of the molecular mechanisms underlying heavy metal-induced neurological impairments. Therefore, brain tissue and serum samples were collected from rats exposed to a Pb, Cd, and Hg mixture for proteomic and metabolomic analyses, respectively. The analysis revealed 363 differential proteins in the brain and 206 metabolites in serum uniquely altered in the Pb, Cd, and Hg mixture exposure group, compared to those of the control group. The main metabolic impacted pathways were unsaturated fatty acids biosynthesis, linoleic acid metabolism, phenylalanine metabolism, and tryptophan metabolism. We further identified that the levels of arachidonic acid (C20:4 n-3) and, adrenic acid (C22:4 n-3) were elevated and that kynurenic acid (KA) and quinolinic acid (QA) levels and the KA/QA ratio, were decreased in the group exposed to the Pb, Cd, and Hg mixture. A joint analysis of the proteome and metabolome showed that significantly altered proteins such as LPCAT3, SLC7A11, ASCL4, and KYAT1 may participate in the neurological impairments induced by the heavy metal mixture. Overall, we hypothesize that the dysregulation of ferroptosis and kynurenine pathways is associated with neurological damage due to chronic exposure to a heavy metal mixture.

Co-exposure to low-dose lead, cadmium, and mercury promotes memory deficits in rats: Insights from the dynamics of dendritic spine pruning in brain development

Lead (Pb), cadmium (Cd), and mercury (Hg) are environmentally toxic heavy metals that can be simultaneously detected at low levels in the blood of the general population. Although our previous studies have demonstrated neurodevelopmental toxicity upon co-exposure to these heavy metals at these low levels, the precise mechanisms remain largely unknown. Dendritic spines are the structural foundation of memory and undergo significant dynamic changes during development. This study focused on the dynamics of dendritic spines during brain development following Pb, Cd, and Hg co-exposure-induced memory impairment. First, the dynamic characteristics of dendritic spines in the prefrontal cortex were observed throughout the life cycle of normal rats. We observed that dendritic spines increased rapidly from birth to their peak value at weaning, followed by significant pruning and a decrease during adolescence. Dendritic spines tended to be stable until their loss in old age. Subsequently, a rat model of low-dose Pb, Cd, and Hg co-exposure from embryo to adolescence was established. The results showed that exposure to low doses of heavy metals equivalent to those detected in the blood of the general population impaired spatial memory and altered the dynamics of dendritic spine pruning from weaning to adolescence. Proteomic analysis of brain and blood samples suggested that differentially expressed proteins upon heavy metal exposure were enriched in dendritic spine-related cytoskeletal regulation and axon guidance signaling pathways and that cofilin was enriched in both of these pathways. Further experiments confirmed that heavy metal exposure altered actin cytoskeleton dynamics and disturbed the dendritic spine pruning-related LIM domain kinase 1-cofilin pathway in the rat prefrontal cortex. Our findings demonstrate that low-dose Pb, Cd, and Hg co-exposure may promote memory impairment by perturbing dendritic spine dynamics through dendritic spine pruning-related signaling pathways.

Cytotoxicity of Nine Medicinal Plants from San Basilio de Palenque (Colombia) on HepG2 Cells

The utilization of plants with medicinal properties is deeply rooted in the traditional knowledge of diverse human populations. This study aims to investigate the cytotoxicity of nine plants commonly used by communities in San Basilio de Palenque, Bolivar (Colombia), for managing inflammation-related illnesses. Hydroethanolic extracts from various plant parts such as roots, stems, barks, or leaves were prepared through a process involving drying, powdering, and maceration in an ethanol-water (7:3) solution. The extracts were subsequently freeze-dried and dissolved in DMSO for the bioassays. Cytotoxicity against the human hepatoma HepG2 cell line was assessed using the MTT assay, with extract concentrations ranging from 0 to 500 µg/mL and treatment durations of 24 and 48 h. The total phenolic content of the nine extracts varied from 96.7 to 167.6 mg GAE/g DT. Among them, eight hydroethanolic extracts from Jatropha gossypiifolia L., Piper peltatum L., Malachra alceifolia, Verbesina turbacensis, Ricinus communis, Desmodium incanum, and Dolichandra unguis-cati showed low toxicity (IC₅₀ > 500 µg/mL, 24 h) against HepG2 cells. On the other hand, the extracts of Aristolochia odoratissima L. (IC₅₀ = 95.7 µg/mL) and Picramnia latifolia (IC₅₀ = 128.9 µg/mL) demonstrated the highest cytotoxicity against the HepG2 cell line, displaying a modest selectivity index when compared to the HEKn cell line after 48 h of treatment. These findings suggest that medicinal plants from San Basilio de Palenque, particularly Picramnia latifolia and Aristolochia odoratissima, have potential activity against cancer cells, highlighting their potential for further research and development.

Modification by genetic polymorphism of lead-induced IQ alteration: a systematic review

As well as a lead-related environmental factor, genetic factors could also corroborate important changes in intelligence quotient (IQ) through single-nucleotide polymorphisms. Thus, a systematic review was carried out to evaluate the possible influence of polymorphism on blood Pb levels and IQ points in pediatric patients (0-19 years old). Following the PRISMA guideline, the studies were systematically collected on PubMed, Scopus, and Embase databases. Six genes (transferrin (TF); glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A); glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B); dopamine receptor D2/ankyrin repeat and kinase domain containing 1 ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1); aminolevulinate dehydratase (ALAD); vitamin D receptor (VDR)) were found in six selected articles. In these genes, 11 single-nucleotide polymorphisms were searched and six different types of variations (missense variant, intron variant, synonymous variant, stop, stop gained) were observed. Due to the few studies in the literature, there is no conclusive data to point out that there is a direct relationship between polymorphisms, Pb levels, and reduction of IQ points.

Exposure to heavy metals and red blood cell parameters in children: A systematic review of observational studies

BACKGROUND

Mechanistic studies show that heavy metals interfere with the hematopoietic system by inhibiting key enzymes, which could lead to anemia. However, the link between children's exposure and red blood cell (RBC) parameters has been inconsistent. We aimed to summarize evidence on human studies exploring the association between exposure to lead, mercury, cadmium, arsenic, and chromium VI and RBC parameters in children.

METHODS

Following the PRISMA guidelines, we searched PubMed, Scopus, and Web of Science databases for studies published between January 2010 and April 2022. Eligible papers included human observational studies that directly assessed exposure (internal dose) to the heavy metals under study and RBC parameters in participants aged ≤ 18 years. We excluded studies using hospital-based samples. Study quality was assessed using the National Institutes of Health's Quality Assessment Tools for Cohort and Cross-Sectional Studies. We synthesized the evidence using vote counting based on the direction of the relationship.

RESULTS

Out of 6,652 retrieved papers, we included a total of 38 (33 assessing lead, four mercury, two cadmium, and two arsenic; chromium VI was not assessed in any included paper). More than half of the studies were conducted in Asia. We found evidence of a positive relationship between lead concentration and hemoglobin (proportion of studies reporting negative relationships = 0.750; 95% Confidence Interval (CI) 0.583, 0.874) and mean corpuscular hemoglobin (0.875; 95% CI 0.546, 0.986), and a positive relationship with red cell distribution width (0.000; 95%CI 0.000, 0.379). When considering only good-quality studies (24% of the Pb studies), only the relationship with hemoglobin levels remained (0.875; 95% CI: 0.546, 0.986).

CONCLUSION

We found evidence of a negative relationship between lead concentration and hemoglobin and mean corpuscular hemoglobin and of a positive relationship with red cell distribution width in children. We also identified a need to conduct more studies in European countries. Future studies should use standardized practices and make efforts to increase study quality, namely by conducting comprehensive longitudinal studies. Our findings support the need to take further actions to limit heavy metal exposure during childhood.

Trace elements, peripheral blood film, and gene expression status in adolescents living near an industrial area in the Colombian Caribbean Coastline

BACKGROUND

Trace elements comprise both nutritionally essential and non-essential, and their presence in organisms plays important role in human health.

OBJECTIVE

The aim of this study was to evaluate the levels of trace elements, together with cellular and molecular biomarkers, in adolescents from Tierrabomba Island, a Caribbean community located near an industrial area, comparing them with a group living in San Onofre, a reference community.

METHODS

Hair and blood samples were obtained from 238 individuals aged 11-18 years old, 131 from Tierrabomba Island and 107 from San Onofre. Trace elements were quantified in hair using ICP-MS. The hematological evaluation was done by peripheral blood smears, and gene expression analysis was carried out through RT-PCR.

RESULTS

Thirteen elements were analyzed; eight showed significant differences between sites. In Tierrabomba, arsenic (As) and tungsten (W) registered mean values greater than in San Onofre. In contrast, in the reference site, average values for boron (B), cobalt (Co), zinc (Zn), yttrium (Y), tin (Sn), and barium (Ba) were greater. The peripheral blood film showed differences between populations. Mean lymphocyte percentage was higher in the Island, while eosinophil and monocyte percentages displayed greater means in San Onofre. Some correlations between trace elements and hematological parameters were found, mainly with platelets in Tierrabomba. This trend remained even when partial correlation coefficients were adjusted for age. Levels of gene expression of metallothionein 1X (MT1X) and superoxide dismutase (SOD) registered significant differences between sites, being greater in Tierrabomba. Negative correlations between SOD and As were observed in both sampling sites. Discriminant analysis suggested sampling locations could be differentiated by Zn, Mo, Ba, and MT1X levels.

SIGNIFICANCE

Trace elements and the relative gene expression associated with metal exposure are critical exposure biomarkers for coastal communities.

Associations between hair levels of trace elements and the risk of preterm birth among pregnant Wwomen: A prospective nested case-control study in Beijing Birth Cohort (BBC), China

Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.

Distribution and health-ecological risk assessment of heavy metals: an endemic disease case study in southwestern China

This research focuses on the health risks caused by heavy metal (HM) environmental pollution. Soil, water, corn, rice, and patients' hair samples from Daping Village, Yunnan Province, China, were analyzed for seven selected HMs. Geoaccumulation index (I_geo), pollution indexes (PI), and the Nemerow integrated pollution index (PN) were used to evaluate pollution levels. We employed principal component analysis (PCA), correlation analysis (CA), and spatial distribution to identify the source and distribution characteristics of HMs in soil. Health risks of HMs and exposure pathways were accessed by calculating the hazard quotient (HQ) and hazard index (HI). The I_geo, PI, and PN results show that cadmium (Cd) and arsenic (As) pollution is severe in soil, while other pollution is relatively little. PCA, CA, and spatial distribution show that HMs may be derived from black shale weathering and enrichment. Residents' drinking water is relatively safe. Arsenic is the element most threatening to local residents (HI = 3.8). Soil (HI = 3.55) ingestion and plant (HI = 1.67) ingestion are the primary exposure pathways to HMs. This unusual disease may be caused by children's relatively low immunity and long-term exposure to As. We must enhance the protection of children and encourage avoiding soil contact as much as possible. Our results highlight the importance of investigating HM pollution from geological sources and blocking potential exposure pathways.

IQ alteration induced by lead in developed and underdeveloped/developing countries: A systematic review and a meta-analysis

The aim of this study was to evaluate the effects of Pb exposure on full-scale IQ score in pediatric subjects. Following PRISMA guidelines, the data from January 2010 to April 2020 were systematically searched and collected on electronic databases (PubMed, Scopus, and Embase). The eligibility criteria included cross-sectional, cohort, and case-control studies that were published in English, from 2010 to 2020, that analyzed the blood Pb levels of pediatric subjects (0-19 years) and possible changes in the full-scale IQ score. In this study, 2174 scientific papers were collected from three electronic databases. From those, 726 were duplicates and 1421 were excluded because they did not meet the eligibility criteria, resulting in a total of 27 papers, from which, seven were used to perform the meta-analysis. The 27 scientific papers systematically selected for this study were separated by the country where the study was realized in developed and underdeveloped/developing countries. In the underdeveloped/developing countries the blood Pb levels are higher and showed a greater variation (1.30-11.66 μgPb/dL of blood) than in countries with higher development index (0.57-4.80 μgPb/dL of blood). The full-scale IQ score are inversely proportional to the blood Pb values, and it is possible to see that in the underdeveloped/developing countries the full-scale IQ score showed lower values and greater variation (59.2-111) compared to the individuals from developed countries (91.9-114.5). In conclusion, it was observed that blood Pb levels alter the full-scale IQ score. Thus, policies for the prevention of environmental contamination and the reduction of Pb exposure must be taken, mainly, in underdeveloped/developing countries.

Correlation between lead exposure and cognitive function in 12-year-old children: a systematic review and meta-analysis

Lead exposure as a toxic material especially in children can be recognized as a harmful factor for cognitive function system. This meta-analysis was conducted to estimate the lead exposure effect on cognitive function among 6979 children less than 12 years. The 16 studies were divided into two clusters according to "duration of exposure" and "dose" using k-means partitioning clustering algorithm. Then, subgroup analysis has been performed based on the clustered studies. According to the results of the k-means clustering, dose and duration of exposure were significant factors between all considered variables. A stronger negative significant pooled correlation was observed in higher dose and duration cluster in comparison with another cluster including lower dose and duration (r = - 0.29, P-value < 0.001 vs. r = - 0.08, P-value < 0.001). Overall, a negative significant correlation was observed between lead exposure and cognitive function test score (r = - 0.22, P-value < 0.001). This study confirms the negative effect of lead on cognitive function in children, but needed further investigations to achieve the safe dose and duration of the lead exposure.

Early occupational exposure to lead on neutrophil-to-lymphocyte ratio and genotoxicity

BACKGROUND

Lead (Pb) is known to induce detrimental health effects in exposed populations, including hematotoxicity and genotoxicity. Complete blood count (CBC) is a cost-effective and easy way to determine toxicity, and variations in proportion of different types of leukocytes: neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) are further evidence of hematotoxicity. However, few studies have been conducted to systematically evaluate effects of occupational Pb exposure on NLR and LMR, and their associations with genotoxicity.

OBJECTIVES

Our study was aimed to systematically assess the effects of current occupational Pb exposure on NLR and LMR, and their associations with genotoxicity.

METHODS

Our investigation was performed on 1176 workers from a newly built battery factory in North China. The workers had just entered their current job position in recent years and most of them had no previous history of occupational exposure to Pb. Blood lead levels (BLLs) and leukocytes indices were detected for all participants. Cytokinesis-blocked micronucleus assay (MN; n = 675) and alkaline comet assay (% tail DNA; n = 869) were used to assess genotoxicity. Multivariate linear and Poisson regression analyses were conducted to examine associations between leukocytes indices, genotoxic biomarkers and BLLs with adjustment for covariates. Spearman correlation and mediation analyses were used to investigate relationships between NLR and genotoxicity.

RESULTS

Among all the exposed workers, NLR increased with increasing BLLs. However, WBC and LMR did not change significantly. Significant and dose-dependent increases in both MN frequencies and % tail DNA were observed among groups with different exposure doses. Compared with the normal NLR group (1.48 ≤ NLR < 4.58), the high NLR group (NLR ≥ 4.58) had higher % tail DNA. In addition, there was a significant and positive association between NLR and % tail DNA among all the workers, and % tail DNA mediated 15% of the effect of Pb on increasing NLR.

CONCLUSION

Our large-scale population study shows that Pb exposure increased NLR and induced genotoxicity. There was an association between elevated NLR and DNA damage. In addition, the mediation effect of % tail DNA on the relationship between BLLs and NLR provided mechanistic evidence that certain mechanisms, e.g. inflammation, may be involved in elevation of NLR from Pb exposure. Therefore, NLR may be a convenient and sensitive biomarker for indication of Pb toxicity. Further studies are needed to validate the proposed mechanism and NLR as a biomarker.

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.

Nanochannel-based sensor for the detection of lead ions in traditional Chinese medicine

Lead ions (Pb2+) are used in the quality control of traditional Chinese medicine (TCM) preparations because they are highly toxic to human health. At present, sophisticated analytical instrumentation and complicated procedures for sample analysis are needed for the determination of Pb2+. Herein, a simple, fast, and sensitive peptide-modified nanochannel sensor to detect Pb2+ in TCM is reported, which is based on a Pb2+-specific peptide modified porous anodized aluminum membrane (PAAM). This peptide-based nanochannel clearly has the highest selectivity for Pb2+ when compared to other heavy metal ions, including As2+, Cd3+, Co2+, Cr2+, Cu2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, and Zn2+. Based on linear ranges from 0.01 to 0.16 μM and 10 to 100 μM, the detection limit was calculated to be 0.005 μM. Moreover, this peptide-based nanochannel sensor was successfully used to detect Pb2+ in complex TCM samples. In addition, when compared with the gold standard atomic absorption spectrophotometry (AAS) method, the recovery of the peptide-modified nanochannel sensor was between 87.7% and 116.8%. The experimental results prove that this new sensor is able to achieve accurate detection of Pb2+ in TCM samples. Thus, this sensor system could provide a simple assay for sensitive and selective detection of Pb2+ in TCM, thereby showing great potential in the practical application for the quality control of heavy metals in TCM.

Biomonitoring of Mercury, Cadmium and Selenium in Fish and the Population of Puerto Nariño, at the Southern Corner of the Colombian Amazon

Heavy metals threaten communities near biodiversity hotspots, as their protein sources come from the environment. This study assessed Hg, Cd, and Se concentrations in fish, as well as the magnitude of exposure and hematological conditions of adult citizens from Puerto Nariño (Colombian Amazon). Among fish samples, greater Hg concentrations were found in higher trophic level species, including Rhaphiodon vulpinus (880 ± 130 ng/g) and Pseudoplatystoma tigrinum (920 ± 87 ng/g). These species presented the highest hazard quotients and lowest Se:Hg molar ratios among those studied, showing their consumption represents a health risk to consumers. Moreover, some samples of Mylossoma duriventre and Prochilodus magdalenae had Cd levels greater than the regulated limit (100 ng/g). The average total Hg (T-Hg) concentrations in human hair and blood were 5.31 µg/g and 13.7 µg/L, respectively. All hair samples exceeded the 1.0 μg/g threshold set by the USEPA, whereas 93% of the volunteers had T-Hg blood levels greater than 5 μg/L, suggesting elevated exposure. The mean Cd level was 3.1 µg/L, with 21% of samples surpassing 5 µg/L, value at which mitigating actions should be taken. Eighty-four percent of participants presented Se deficiencies (<100 μg/L). There was a significant association between fish consumption and T-Hg in hair (ρ = 0.323; p = 0.032) and blood (ρ = 0.381; p = 0.011). In this last matrix, Se correlated with Cd content, whereas lymphocytes were inversely linked to Hg concentrations. The results of this study show that there is  extensive exposure to Hg in fish, the consumption of which may promote detrimental impacts on hematology parameters within the community.

Investigating the Status of Cadmium, Chromium and Lead in the Drinking Water Supply Chain to Ensure Drinking Water Quality in Malaysia

Prolonged persistence of toxic cadmium (Cd), chromium (Cr) and lead (Pb) in the aquatic environment are due to its nonbiodegradable characteristic. A few studies have reported higher concentrations of these metals in the transboundary Langat River, Malaysia. This study determined the spatial and temporal distributions of Cd, Cr and Pb concentrations (2005–2015) in the Langat River along with assessing the status of these metals in the drinking water supply chain at the basin. Water samples were collected once in 2015 from the drinking water supply chain, i.e., from the river, treated water at plants, taps and filtration water at households. Determined mean concentrations of Cd, Cr and Pb by inductively coupled plasma mass spectrometry in the Langat River were within the drinking water quality standard of Malaysia and the WHO, except for the Pb (9.99 ± 1.40 µg/L) concentration, which was at the maximum limit, 10 µg/L. The spatial and temporal distribution of these metals’ concentrations indicate dilution of it downstream, along with the increasing trend in rainfall and water flow, especially during the northeast monsoon. Significant correlation and regression analysis of the Cd, Cr and Pb concentrations also indicate that the sources of this metal pollution are mainly the natural weathering of minerals along with anthropogenic activities in the basin. The determined overall water quality of the Langat River is categorized Class IIA (i.e., clean), which requires conventional treatment before drinking; however, the maximum removal efficiency of these metals by the plants at the basin was about 90.17%. Therefore, the proactive leadership roles of the local authorities will be appropriate to reduce the pollution of this river as well as introducing a two-layer water filtration system at the Langat River Basin to accelerate the achievement of a sustainable drinking water supply.

Hydrochemical composition and potentially toxic elements in the Kyrgyzstan portion of the transboundary Chu-Talas river basin, Central Asia

Water chemistry and the assessment of health risks of potentially toxic elements have important research significance for water resource utilization and human health. However, not enough attention has been paid to the study of surface water environments in many parts of Central Asia. Sixty water samples were collected from the transboundary river basin of Chu-Talas during periods of high and low river flow, and the hydrochemical composition, including major ions and potentially toxic elements (Zn, Pb, Cu, Cr, and As), was used to determine the status of irrigation suitability and risks to human health. The results suggest that major ions in river water throughout the entire basin are mainly affected by water-rock interactions, resulting in the dissolution and weathering of carbonate and silicate rocks. The concentrations of major ions change to some extent with different hydrological periods; however, the hydrochemical type of calcium carbonate remains unchanged. Based on the water-quality assessment, river water in the basin is classified as excellent/good for irrigation. The relationship between potentially toxic elements (Zn, Pb, Cu, Cr, and As) and major ions is basically the same between periods of high and low river flow. There are significant differences between the sources of potentially toxic elements (Zn, Pb, Cu, and As) and major ions; however, Cr may share the same rock source as major ions. The risk assessment revealed low non-carcinogenic and carcinogenic risks for human health; however, the maximum carcinogenic risk for As exceeded the allowable value, which requires further consideration. These results provide a scientific basis for the management of agricultural irrigation uses and also infill existing gaps regarding the hydrochemical composition in the Chu-Talas river basin, Central Asia.

Effect of lead on proliferation, oxidative stress and genotoxic damage of 3T3-L1 fibroblasts

Lead (Pb) is an environmental and industrial contaminant that still represents a public health problem. In this paper, we investigated the effect of Pb on proliferation, lipid peroxidation and the number of micronucleated cells in exponentially growing 3T3-L1 fibroblasts, a cell line previously used to evaluate different environmental contaminants. We found that Pb (10 μM or higher) was able to inhibit proliferation of exponentially growing cells after 24-h treatment, which was evaluated by the MTT assay and cell counting in Neubauer chamber, but cell survival was not affected according to the trypan blue exclusion assay. On the other hand, Pb was able to increase lipid peroxidation and the number of micronucleated cells, which are indicative of oxidative stress and genotoxic damage respectively. We also found that removal of Pb after 24-h treatment allowed cells to recover proliferation. Our results indicate that Pb was able to induce oxidative stress and genotoxicity in this cell line under standardized conditions, which supports the involvement of Pb in similar effects observed in human exposed to this heavy metal. In addition, Pb inhibits proliferation of exponentially growing fibroblasts but cells resume proliferation after removal of this metal, which suggests that it is important to move away Pb-exposed individuals from the source of contamination.

Insights into cognitive deficits caused by low-dose toxic heavy metal mixtures and their remediation through a postnatal enriched environment in rats

The heavy metals, namely lead (Pb), cadmium (Cd), and mercury (Hg), have been studied extensively in various independent studies. It has been seen that these metals are usually detected simultaneously in the human blood at low levels. However, it is unknown whether exposure to these heavy metal mixtures (MM) can induce neurological damages at these low levels. Therefore, we investigated the influence of the Pb, Cd, and Hg mixture on the nervous system in rats at exposure doses equivalent to those normally found in the human blood. After pregnant rats being exposed to MM via drinking water throughout the gestation and lactation, their offspring were followed-up till adulthood. MM caused cognitive deficits and impairments in a dose-dependent manner. Furthermore, MM disrupted dendritic spines, the structural basis of learning and memory, and induced changes in spine-related pathways. Meanwhile, we explored an early and safe way to remedy these impairments through a postnatal enriched environment. The enriched environment ameliorated MM-impaired cognitive function, synaptic plasticity, and spine-related pathways. This study demonstrated that low-dose co-exposure to Pb, Cd, and Hg can cause cognitive and synaptic plasticity deficits and timely intervention through the enriched environment has a certain corrective effect.

Screening for Elevated Blood Lead Levels and Related Risk Factors among Thai Children Residing in a Fishing Community

The present study explored environmental and behavioral factors associated with elevated blood lead (Pb) levels in 311 children (151 girls and 160 boys), aged 3–7 years, who lived in a coastal fishing community of the Pakpoon Municipality, Nakhon Si Thammarat, Thailand. The geometric mean for blood Pb was 2.81 µg/dL, ranging between 0.03 and 26.40 µg/dL. The percentage of high blood Pb levels, defined as blood Pb ≥ 5 µg/dL, was 10.0% in boys and 13.9% in girls. Parental occupation in producing fishing nets with lead weights was associated with a marked increase in the prevalence odds ratio (POR) for high blood Pb (POR 17.54, 95%; CI: 7.093, 43.390; p < 0.001), while milk consumption was associated with 61% reduction in the POR for high blood Pb (POR 0.393, 95%; CI: 0.166, 0.931; p = 0.034). High blood Pb was associated with an increased risk for abnormal growth (POR 2.042, 95%; CI: 0.999, 4.174; p = 0.050). In contrast, milk consumption was associated with a 43% reduction in POR for abnormal growth (POR 0.573, 95%; CI: 0.337, 0.976; p = 0.040). After adjustment for age, the mean (standard error of mean, SE) values for blood Pb were 6.22 (0.50) μg/dL in boys and 6.72 (0.49) μg/dL in girls of parents with an occupation in making fishing nets with lead weights. These mean blood Pb values were respectively 2.3 and 2.5 times higher than similarly aged boys and girls of parents with other occupations. These data are essential for setting surveillance and programmes to prevent toxic Pb exposure, especially in children of coastal fishing communities in southern Thailand.