Mechanisms Associated with Cognitive and Behavioral Impairment Induced by Arsenic Exposure

Inorganic arsenic in aquatic products in Shenzhen, China from 2018 to 2024: Levels, temporal variation and health risk assessment

Aquatic products are a significant source of arsenic exposure, with inorganic arsenic (iAs) posing a significant risk to humans. This study assessed iAs levels in 1191 aquatic products from Shenzhen, China (2018-2024), and estimated health risks. Shellfish had lower mean iAs levels (0.01 mg/kg ∼ 0.07 mg/kg), while crab, fish, and shrimp had higher levels (0.04 mg/kg ∼ 0.06 mg/kg). The iAs levels in shellfish were stable from 2018 to 2024. Health risk assessments showed estimated daily intake values ranging from 0.01 μg/kg·bw/day to 0.39 μg/kg·bw/day, with children having the highest exposure. The target hazard quotient exceeded 1 for fish and shrimp in high-consumption scenarios for children, indicating potential non-carcinogenic risks. Cancer risk estimates surpassed acceptable thresholds, especially for children and adolescents, suggesting an increased cancer risk with high consumption. Authorities should strengthen surveillance of iAs in aquatic products, especially shellfish and shrimp, and enhance environmental monitoring in Shenzhen.

Water sources and educational attainment in Colombian adults: evidence from the national nutritional survey

BACKGROUND

Academic achievement is essential to people's individual and social development by enhancing opportunities for significant personal achievement throughout life. Exposure to toxic agents due to poor water quality may negatively influence neurodevelopment in children and adolescents into adulthood.

OBJECTIVE

We aimed to estimate the association between the type of water for drinking purposes and academic achievements in Colombian adults.

METHODS

We designed a cross-sectional study based on the National Survey of Nutritional Situation in Colombia (Encuesta Nacional de la Situación Nutricional en Colombia -ENSIN-) 2015. Academic achievement in our study was classified as less than complete primary school (0-4 years), between complete primary and incomplete secondary (5-10 years), between complete secondary and incomplete higher education (11-15 years), and complete higher education and more (16-24 years). We utilized adjusted ordinal logistic regression to estimate betas (β's) and Odds Ratio [OR] with 95% confidence intervals [95%CI].

RESULTS

After adjusting for potential confounders, we report an inverse association between consumption of untreated water and academic attainments, where individuals who drink surface water [β: -0.625; 95%CI: -0.629, -0.620], or groundwater [β: -0.368; 95%CI: -0.372, -0.364] were less likely to achieve higher educational levels compared to those consuming treated water. This pattern was similar across the country when disaggregated by region.

CONCLUSION

We found that people with lower levels of education are more likely to consume untreated water in Colombia. Our results encourage improving access to treated water to the population with an emphasis on rural communities and the Atlantic region.

Alzheimer's Disease and Circulatory Imbalance of Toxic Heavy Metals: A Systematic Review and Meta-analysis of Clinical Studies

The role of heavy metals on human health has often been discussed regarding disease pathogenesis and risk factors. Alzheimer's disease (AD), a prevalent neurodegenerative disease, is no exception. We conducted a comprehensive examination to assess the concentrations of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in biological samples of AD patients in comparison with a group of individuals without AD, with the objective of our study being to perform a systematic review on this topic. We performed this systematic review by searching various databases/search engines, including Web of Science, Scopus, PubMed, and Google Scholar, until December 7, 2022. Relevant studies were scrutinized for eligibility. Meta-analysis was performed on studies with sufficient data using STATA software. Twenty-seven out of 3349 studies met pre-defined eligibility criteria and were included in our systematic review. For the meta-analysis, 22 studies with 3346 participants (1291 AD patients and 2055 healthy controls) had sufficient data for inclusion in the analysis. Using a random-effects model, we found that pooled data indicated patients with AD had significantly higher levels of Cd in their biological samples compared to controls (Hedges' g, 0.83; 95% CI, 0.11, 1.54; p = 0.023). However, other heavy metals were not significantly different in circulatory samples of AD patients compared to healthy controls (p > 0.05). This systematic review and meta-analysis indicated that Cd concentrations in AD patients were significantly higher than in healthy controls. Other included heavy metals may not be directly associated with increased risk of AD.

Evaluation of Heavy Metals and Essential Minerals in the Hair of Children with Autism Spectrum Disorder and Their Association with Symptom Severity

The exact cause of Autism spectrum disorder (ASD) remains unclear. The accumulation of heavy metals and the imbalance of trace elements are believed to play a key role in the pathogenesis of ASD. This study aimed to compare the levels of trace elements and heavy metals in the hair of 1-16-year-old children with varying ASD severity. We included a control group of 57 children, as well as 124 children with autism, consisting of 53 with mild to moderate autism and 71 with severe autism. Questionnaires and hair samples were collected, and 21 chemical elements were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Children with severe autism showed significantly higher levels of the trace elements copper (Cu) and heavy metals vanadium (V), cobalt (Co), nickel (Ni), arsenic (As), cadmium (Cd), and lead (Pb) in their bodies compared to the control group. Boys with severe autism showed significantly higher levels of Cu, As, Cd, and Pb compared to the control group, while girls with severe autism exhibited significantly lower levels of potassium (K) and increased levels of Pb. Severely autistic children under 7 years old had significantly increased levels of Mn, Cu, V, Co, Ni, As, Cd, and Pb. Children with severe autism aged 7-16 years typically showed significantly higher levels of Cu and As. These findings underscore the importance of heavy metals and essential minerals as environmental factors in the severity of ASD disease.

A comprehensive review of arsenic-induced neurotoxicity: Exploring the role of glial cell pathways and mechanisms

The review aims to examine the neurotoxic effects of arsenic, particularly exploring the roles of glial cells-astrocytes, microglia, and oligodendrocytes, amid its widespread environmental contamination and impact on cognitive impairments. It highlights the role of altered neurotrophin and growth factor signaling in disrupting neuronal health and cognitive performance. It elucidates the intricate interactions between oxidative stress, DNA damage, neurotransmitter disruption, and cellular signaling alterations, underscoring the vital importance of the glial cells. These cells are crucial for preserving neural health and responding to environmental toxins, and arsenic disrupts their functions, resulting in decreased antioxidative responses, induction of inflammatory pathways, and subsequent neuronal dysfunction. The brain's cytotoxic impact arises from a complex network of cellular responses, with pathways such as MAPK, transcription factor and autophagy signaling to play critical roles in mediating these dysregulated inflammation and oxidative stress mechanisms. The detailed exploration into specific impacts of arsenic on glial cell morphology, activation, and mitochondrial functions illuminates the cascade of neuroinflammatory and neurodegenerative changes that may be triggered upon arsenic exposure. The review recommends a multidisciplinary research approach by emphasizing the significance of the brain's microenvironment, methylation processes, and the enzyme AS3MT in arsenic neurotoxicity. It calls for converging environmental science, neurobiology, and toxicology to develop targeted interventions for preventing and mitigating arsenic's neurotoxic effects. This in-depth exploration into glial cell dynamics aims to advance public health and neurotoxicology research, striving to devise strategies that reduce the cognitive and neurodegenerative damage caused by arsenic, thereby enhancing global health outcomes.

Curcumin alleviates arsenic trioxide-induced neural damage in the murine striatal region

RATIONALE

Arsenic-induced neurotoxicity, with dose-dependent effects, is well-documented in rodents. Curcumin (CUR), a cost-effective plant polyphenol, shows neuroprotective effects by modulating oxidative stress, apoptosis, and neurochemistry. This study evaluates curcumin's neuroprotective potential against arsenic trioxide (As2O3) in the mouse striatal region.

METHODS

Healthy adult male mice were chronically administered with varying concentrations of As2O3 (2, 4 and 8 mg/kg bw) alone and along with CUR (100 mg/kg bw) orally for 45 days. Towards the end of the experimental period, the animals were subjected to behavioural paradigms including open field task, novel object recognition, rota-rod, and Morris water maze. Striatal tissues were freshly collected from the animals on day 46 for biochemical analyses (MDA, GPx, and GSH). Additionally, perfusion-fixed brains were processed for morphological observations.

RESULTS

Behavioural study showed an apparent decrease in certain cognitive functions (learning and memory) and locomotor activity in mice exposed to As2O3 compared to controls. Simultaneous treatment of As2O3 (2, 4 and 8 mg/kg bw) and curcumin (100 mg/kg bw) alleviated the As-induced locomotor and cognitive deficits. As2O3 alone exposure also exhibited a significant increase in oxidative stress marker (MDA) and a decrease in antioxidant enzyme levels (GPx, GSH). Morphological alterations were noted in mice subjected to elevated doses of As2O3 (4 and 8 mg/kg bw). However, these changes were reversed in mice who received As2O3 + CUR co-treatment.

CONCLUSIONS

Collectively, our findings indicate that curcumin offers neuroprotection to the striatal region against As2O3-induced behavioral deficits, as well as biochemical and morphological alterations.

Exposure to arsenic and cognitive impairment in children: A systematic review

OBJECTIVE

Arsenic exposure is a significant public health concern, particularly for its impact on children's cognitive development. Arsenic, a prevalent environmental toxin, is known to disrupt various biological pathways, leading to cognitive deficits and neurodevelopmental issues. Understanding the long-term effects and mechanisms underlying arsenic-induced cognitive impairments is crucial for devising effective interventions.

METHODS

This systematic review included observational and experimental studies focusing on children under 18 years exposed to arsenic through drinking water, food, or other environmental sources. Studies were selected through comprehensive database searches, encompassing articles that measured cognitive outcomes via standardized tests. The synthesis was primarily narrative, given the heterogeneity in study designs, exposure levels, and outcomes.

RESULTS

The review analysed findings from 24 studies, showing a consistent inverse relationship between arsenic exposure and cognitive performance in children. Higher arsenic levels were associated with lower IQ scores, slower processing speeds, and impaired memory and language skills. These cognitive deficits were evident across diverse geographical regions and persisted even after adjusting for sociodemographic factors. The studies highlighted the potential for both immediate and long-term cognitive effects, underscoring the importance of early-life exposure.

CONCLUSIONS

Arsenic exposure has the potential to impair cognitive development in children. Nonetheless, quantitative meta-analysis is necessary to deduce any conclusions related to its impact. Public health efforts must prioritize reducing arsenic exposure through improved water quality and community-awareness programs. Future research should focus on longitudinal studies to better understand the dose-response relationship and the effectiveness of intervention strategies.

SYSTEMATIC REVIEW REGISTRATION

Prospero, CRD42024544442.

Cerebellar pathology in forensic and clinical neuroscience

Recent research underscores the cerebellum's growing importance in forensic science and neurology, showing its functions extend beyond motor control, especially in identifying causes of death. Critical neuropathological markers including alpha-synuclein and tau protein aggregates, cellular degeneration, inflammation, and vascular changes are vital for identifying neurodegenerative diseases, injuries, and toxic exposures. Advanced forensic methods, such as Magnetic resonance imaging (MRI), immunohistochemistry, and molecular analysis, have greatly improved the accuracy of diagnoses. Promising new therapies, including neuroprotective agents like resveratrol and transcranial magnetic stimulation (TMS), offer potential in treating cerebellar disorders. The cerebellum's vulnerability to toxins, drugs, and traumatic brain injuries (TBIs) highlights its forensic relevance. Moreover, advancements in genetic diagnostics, such as next-generation sequencing and CRISPR-Cas9, are enhancing the understanding and treatment of genetic conditions like Joubert syndrome and Dandy-Walker malformation. These findings emphasize the need for further research into cerebellar function and its broader significance in both forensic science and neurology.

From contamination to detection: The growing threat of heavy metals

Heavy metals like lead, mercury, cadmium, and arsenic are environmental pollutants that accumulate in ecosystems and pose significant health risks to humans and wildlife, primarily through food chain contamination where plants absorb heavy metals, affecting their growth and threatening consumer health. Cognitive and cardiovascular functions are particularly affected by exposure to heavy metals even at low concentrations through the induction of oxidative stress. Various analytical techniques are used in measuring heavy metals in different environmental and biological samples. The atomic absorption spectroscopy (AAS) offers low cost, simplicity, and portability but lacks sensitivity for certain metals. Although more sensitive, the high cost of inductively coupled plasma mass spectrometry (ICP-MS) may limit laboratory accessibility. The inductively coupled plasma with atomic emission spectrometry (ICP-AES) is known for its broad dynamic linear range and ability to identify minute variations in concentration. Atomic fluorescence spectrometry (AFS) is considered a powerful tool for quantifying heavy metals due to its high sensitivity, low detection limits, and wide linear range. The current article reviews heavy metal pollution's impact on health and spectrometric techniques for the detection of these contaminants. This may help efforts of international, and regional policies towards preventing this health hazard problem.

Selective chromogenic nanomolar level sensing of arsenite anions in food samples using dual binding site probes

In the present study, two chromogenic probes, N7R2 and N7R3, each containing two binding sites, were designed and synthesized for the selective detection of arsenite in DMSO/H2O (1:1, v/v). The probes exhibited stability across a pH range spanning from 5 to 12. The lower detection limits of 2.01 ppb (18.86 nM) for N7R2 and 1.79 ppb (16.75 nM) for N7R3, which are much lower than the WHO recommended permissible limit of arsenite, confirmed the superior efficiency of the probes in detecting arsenite. The detection mechanism for arsenite was proposed through UV and 1H NMR titrations, electrochemical studies, and DFT calculations. Practical applications were demonstrated through the fabrication of test strips and molecular logic gates. The probes efficiently recognized arsenite in real water, honey, milk samples, and fruit/vegetable juices. Both N7R2 and N7R3 exhibited excellent recovery rates in the analysis of food samples, demonstrating the probes' usefulness in real sample analysis.

Amelioration of arsenic-induced hepatic injury via sulfated glycosaminoglycan from swim bladder: Modulation of Nrf2 pathway and amino acid metabolism

Arsenic, a known environmental pollutant with a carcinogenic risk, is associated with chronic liver toxicity. Prebiotic regulation represents an emerging dietary strategy to alleviate arsenic-induced hepatotoxicity; however, research in this area remains limited. This study employed sulfated swim bladder glycosaminoglycan (SBSG), a potential prebiotic, to assess its efficacy in mitigating arsenic-induced liver injury. In basic indicators, SBSG resisted oxidative stress by down-regulating AST, ALT, MDA, and MPO, up-regulating antioxidants (T-SOD, GSH, and GSH-px), and ameliorating histopathological damage. RT-qPCR analysis revealed that SBSG could regulate the Nrf2 signaling pathway and affect the expression of o genes related to ferroptosis and detoxification. The expression of protein further verified that SBSG could play an antioxidant and detoxifying role as an Nrf2 activator. Non-targeted metabolomics results demonstrated that SBSG primarily addresses metabolic disorders by up-regulating D-amino acid metabolism, ABC transporter, and alanine, aspartate and glutamate metabolism. Correlation analysis suggests that SBSG alleviates arsenic-induced liver oxidative damage through mechanisms linked to the Nrf2 pathway and amino acid metabolism. This study provided a research basis for expanding the dietary strategy to reduce arsenic induced toxicity.

Abcb1 is involved in the efflux of trivalent inorganic arsenic from brain microvascular endothelial cells

Arsenic (As) can penetrate brain tissue through the blood-brain barrier (BBB), and the ATP-binding cassette subfamily B member 1 (Abcb1) has been shown to facilitate the transport of inorganic arsenic (iAs) in animal liver, small intestine, and yeast. However, the relationship between Abcb1 and BBB has not been reported, and the mechanism of brain microvascular endothelial cells Abcb1 on the transport of iAs needs to be further studied. Increased arsenic levels were observed in mice exposed to 25 mg/L or 50 mg/L of sodium arsenite (NaAsO2) in drinking water, and both arsenic uptake and efflux were detected in bEnd.3 cells treated with 16 μmol/L NaAsO2. Elevated levels of Abcb1 protein were found in the NaAsO2-exposed mouse brain microvascular endothelium and in NaAsO2-treated bEnd.3 cells. Inhibition of Abcb1's efflux function significantly reduced the 2-hour arsenic efflux rate in bEnd.3 cells loaded arsenic. Conversely, overexpression of either Abcb1a or Abcb1b significantly increased the 2-hour arsenic efflux rate in these cells loaded arsenic. These findings suggest that Abcb1 may play a crucial role in mediating arsenic efflux from mouse brain microvascular endothelial cells.

Arsenic Exposure Induces Neuro-immune Toxicity in the Cerebral Cortex and the Hippocampus via Neuroglia and NLRP3 Inflammasome Activation in C57BL/6 Mice

This study aimed to examine the immuntoxic effects of arsenic in the nervous system. Our results showed that arsenic increased corticocerebral and hippocampal weights (p < 0.05). Morris water maze tests revealed that arsenic significantly increased the time spent in latency to platform on the fourth day in 50 mg/L arsenic exposure and the fifth day in 25 and 50 mg/L arsenic exposure, as well as reduced the path length in target quadrant, time spent in target quadrant, and crossing times of the platform (p < 0.05). Hematoxylin-eosin staining showed that the vacuolated degeneration and pyknosis was found in the cerebral cortex and hippocampus of arsenic-treated mice. The mRNA levels of corticocerebral and hippocampal brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) were decreased in the 50 mg/L arsenic-treated group (p < 0.05). In addition, immunofluorescence staining showed that 25 and 50 mg/L arsenic all increased the expression of CD11b and glial fibrillary acidic protein (GFAP) in the cerebral cortex and hippocampus (p < 0.05). Arsenic markedly raised antigen-presenting molecule MHCII and CD40 mRNA levels in the cerebral cortex and hippocampus and upregulated the cell chemokine receptor 5 (CCR5) and CCR7 mRNA levels in the cerebral cortex at the 50 mg/L arsenic group, and increased the CCR7 mRNA levels in the hippocampus at the 25 and 50 mg/L arsenic groups (p < 0.05). Arsenic activated the nucleotide-binding domain-like receptor protein-3 (NLRP3) inflammasome, and enhanced its upstream promoter NF-κB protein level and downstream regulators IL-18 mRNA levels. Collectively, these results provide new evidences for the neuro-immune toxicity of arsenic.

Intrauterine arsenic exposure induces glucose metabolism disorders in adult offspring by targeting TET2-mediated DNA hydroxymethylation reprogramming of HNF4α in developing livers, an effect alleviated by ascorbic acid

Exposure to arsenic during gestation has lasting health-related effects on the developing fetus, including an increase in the risk of metabolic disease later in life. Epigenetics is a potential mechanism involved in this process. Ten-eleven translocation 2 (TET2) has been widely considered as a transferase of 5-hydroxymethylcytosine (5hmC). Here, mice were exposed, via drinking water, to arsenic or arsenic combined with ascorbic acid (AA) during gestation. For adult offspring, intrauterine arsenic exposure exhibited disorders of glucose metabolism, which are associated with DNA hydroxymethylation reprogramming of hepatic nuclear factor 4 alpha (HNF4α). Further molecular structure analysis, by SEC-UV-DAD, SEC-ICP-MS, verified that arsenic binds to the cysteine domain of TET2. Mechanistically, arsenic reduces the stability of TET2 by binding to it, resulting in the decrease of 5hmC levels in Hnf4α and subsequently inhibiting its expression. This leads to the disorders of expression of its downstream key glucose metabolism genes. Supplementation with AA blocked the reduction of TET2 and normalized the 5hmC levels of Hnf4α, thus alleviating the glucose metabolism disorders. Our study provides targets and methods for the prevention of offspring glucose metabolism abnormalities caused by intrauterine arsenic exposure.