The association between mercury levels and autism spectrum disorders: A systematic review and meta-analysis

Controlling of foodborne pathogen biofilms on stainless steel by bacteriophages: A systematic review and meta-analysis

This study investigates the potential of using bacteriophages to control foodborne pathogen biofilms on stainless steel surfaces in the food industry. Biofilm-forming bacteria can attach to stainless steel surfaces, rendering them difficult to eradicate even after a thorough cleaning and sanitizing procedures. Bacteriophages have been proposed as a possible solution, as they can penetrate biofilms and destroy bacterial cells within, reducing the number of viable bacteria and preventing the growth and spread of biofilms. This systematic review and meta-analysis evaluates the potential of bacteriophages against different biofilm-forming foodborne bacteria, including Cronobacter sakazakii, Escherichia coli, Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas aeruginosa and Listeria monocytogenes. Bacteriophage treatment generally causes a significant average reduction of 38 % in biofilm formation of foodborne pathogens on stainless steel. Subgroup analyses revealed that phages are more efficient in long-duration treatment. Also, applying a cocktail of phages is 1.26-fold more effective than applying individual phages. Phages at concentrations exceeding 107 PFU/ml are significantly more efficacious in eradicating bacteria within a biofilm. The antibacterial phage activity decreases substantially by 3.54-fold when applied at 4 °C compared to temperatures above 25 °C. This analysis suggests that bacteriophages can be a promising solution for controlling biofilms in the food industry.

Autism spectrum disorder: Cadmium and mercury concentrations in different biological samples, a systematic literature review and meta-analysis of human studies

The present study was conducted to investigate the differences in cadmium (Cd) and mercury (Hg) concentrations between children with autism spectrum disorder (ASD) and controls. In this systematic review and meta-analysis study, three thousand one hundred forty-five studies were collected from scientific databases including Web of Science, Scopus, PubMed, and Google Scholar from January 2000 to October 2022 and were investigated for eligibility. As a result, 37 studies published in the period from 2003 to 2022 met our inclusion criteria and were considered in the meta-analysis. The heterogeneity assumption was evaluated using the Chi-squared-based Q-test and I-squared (I2) statistics. The pooled estimates were shown in the forest plots with Hedges' g (95% confidence interval) values. The random effects model demonstrated that there is no significant difference in the blood (Hedges' g: 0.14, 95% CI: 0.45, 0.72, p > 0.05), hair (Hedges' g: 0.12, 95% CI: 0.26, 0.50, p > 0.05), and urinary (Hedges' g: 0.05, 95% CI: 0.86, 0.76, p > 0.05) Cd levels of the case group versus control subjects. Moreover, the pooled findings of studies showed no significant difference in the blood (Hedges' g: 1.69, 95% CI: 0.09, 3.48, p > 0.05), hair (Hedges' g: 3.42, 95% CI: 1.96, 8.80, p > 0.05), and urinary (Hedges' g: 0.49, 95% CI: 1.29 - 0.30, p > 0.05) Hg concentrations. The results demonstrated no significant differences in Hg and Cd concentrations in different biological samples of children with ASD compared to control subjects.

Mercury and Autism Spectrum Disorder: Exploring the Link through Comprehensive Review and Meta-Analysis

Mercury (Hg) is a non-essential trace metal with unique neurochemical properties and harmful effects on the central nervous system. In this study, we present a comprehensive review and meta-analysis of peer-reviewed research encompassing five crucial clinical matrices: hair, whole blood, plasma, red blood cells (RBCs), and urine. We assess the disparities in Hg levels between gender- and age-matched neurotypical children (controls) and children diagnosed with autism spectrum disorder (ASD) (cases). After applying rigorous selection criteria, we incorporated a total of 60 case-control studies into our meta-analysis. These studies comprised 25 investigations of Hg levels in hair (controls/cases: 1134/1361), 15 in whole blood (controls/cases: 1019/1345), 6 in plasma (controls/cases: 224/263), 5 in RBCs (controls/cases: 215/293), and 9 in urine (controls/cases: 399/623). This meta-analysis did not include the data of ASD children who received chelation therapy. Our meta-analysis revealed no statistically significant differences in Hg levels in hair and urine between ASD cases and controls. In whole blood, plasma, and RBCs, Hg levels were significantly higher in ASD cases compared to their neurotypical counterparts. This indicates that ASD children could exhibit reduced detoxification capacity for Hg and impaired mechanisms for Hg excretion from their bodies. This underscores the detrimental role of Hg in ASD and underscores the critical importance of monitoring Hg levels in ASD children, particularly in early childhood. These findings emphasize the pressing need for global initiatives aimed at minimizing Hg exposure, thus highlighting the critical intersection of human-environment interaction and neurodevelopment health.

Exposure to heavy metals in utero and autism spectrum disorder at age 3: A meta-analysis of two longitudinal cohorts of siblings of children with autism

Background

Autism spectrum disorder (ASD) is a prevalent and heterogeneous neurodevelopmental disorder. Risk is attributed to genetic and prenatal environmental factors, though the environmental agents are incompletely characterized.

Methods

In Early Autism Risk Longitudinal Investigation (EARLI) and Markers of Autism Risk in Babies Learning Early Signs (MARBLES), two pregnancy cohorts of siblings of children with ASD, maternal urinary metals concentrations at two time points during pregnancy were measured using inductively coupled plasma mass spectrometry. At age three, clinicians assessed ASD with DSM-5 criteria. Using multivariable log binomial regression, we examined each metal for association with ASD status, adjusting for gestational age at urine sampling, child sex, maternal age, and maternal education, and meta-analyzed across the two cohorts.

Results

In EARLI (n=170) 17.6% of children were diagnosed with ASD, and an additional 43.5% were classified as having other non-neurotypical development (Non-TD). In MARBLES (n=156), 22.7% were diagnosed with ASD, while an additional 11.5% had Non-TD. In earlier pregnancy metals measures, having cadmium concentration over the level of detection was associated with 1.78 (1.19, 2.67) times higher risk of ASD, and 1.43 (1.06, 1.92) times higher risk of Non-TD. A doubling of early pregnancy cesium concentration was marginally associated with 1.81 (0.95, 3.42) times higher risk of ASD, and 1.58 (0.95, 2.63) times higher risk of Non-TD.

Conclusion

Exposure in utero to elevated levels of cadmium and cesium, as measured in maternal urine collected during pregnancy, was associated with increased risk of developing ASD.

Abnormal Porphyrin Metabolism in Autism Spectrum Disorder and Therapeutic Implications

Autism spectrum disorder (ASD) is a mosaic of neurodevelopmental conditions composed of early-onset social interaction and communication deficits, along with repetitive and/or restricted patterns of activities, behavior, and interests. ASD affects around 1% of children worldwide, with a male predominance. Energy, porphyrin, and neurotransmitter homeostasis are the key metabolic pathways affected by heavy metal exposure, potentially implicated in the pathogenesis of ASD. Exposure to heavy metals can lead to an altered porphyrin metabolism due to enzyme inhibition by heavy metals. Heavy metal exposure, inborn genetic susceptibility, and abnormal thiol and selenol metabolism may play a significant role in the urinary porphyrin profile anomalies observed in ASD. Altered porphyrin metabolism in ASD may also be associated with, vitamin B6 deficiency, hyperoxalemia, hyperhomocysteinemia, and hypomagnesemia. The present review considers the abnormal porphyrin metabolism in ASD in relation to the potential pathogenic mechanism and discusses the possible metabolic therapies such as vitamins, minerals, cofactors, and antioxidants that need to be explored in future research. Such targeted therapeutic therapies would bring about favorable outcomes such as improvements in core and co-occurring symptoms.

Prenatal and postnatal exposure to heavy metals in PM2.5 and autism spectrum disorder

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders, and its incidence is increasing over time. Although several environmental factors have been suspected to be risk factors for ASD, studies on the effects of airborne heavy metals on newly developed ASD are still limited. We conducted a large birth cohort study of 168,062 live term births in Taichung during 2004-2011 to assess the association of heavy metals in particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) with ASD, and identify sensitive time windows during prenatal and postnatal periods. Heavy metals, including arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in PM2.5, were estimated using the Weather Research and Forecasting/Chem (WRF/Chem), inserted from the top 75 emission sources for the module. The association between childhood ASD and 4 metals were analyzed from pregnancy to 9 months after birth. The Cox proportional hazard model with a distributed lag nonlinear model (DLNM) was used to estimate the association between heavy metals in PM2.5 and ASD. We identified 666 incident ASD cases in 168,062 participants. A positive association between Hg and ASD was found at 9 months after birth (Hazard Ratio: 1.63; 95% CI: 1.13-2.36). According to the DLNM, there was an increased risk of exposure to Hg during 10-25 weeks after birth, and decreased risk of exposure to Hg during gestational weeks 4-6. Exposure to As and Hg on the risk of ASD were significantly stronger in low birth weight infants (<2500 g) than in those of birth weight ≥2500 g during postnatal period. Postnatal exposure to Hg in PM2.5 may associate with increased ASD incidence. Infants with low birth weight and exposure to As and Hg in PM2.5 are more likely to develop ASD.

Identification of potentially relevant metals for the etiology of autism by using a Bayesian multivariate approach for partially censored values

Heavy metals are known to be able to cross the placental and blood brain barriers to affect critical neurodevelopmental processes in the fetus. We measured metal levels (Al, Cd, Hg, Li, Pb and Zn) in the cord blood of newborns and in the serum of the same children at 5 years of age, and compared between individuals with or without (controls) autism spectrum disorder (ASD) diagnosis. The samples were from a biobank associated with the All Babies in Southeast Sweden (ABIS) registry. We proposed a Bayesian multivariate log-normal model for partially censored values to identify potentially relevant metals for the etiology of ASD. Our results in cord blood suggest prenatal Al levels could be indicative of later ASD incidence, which could also be related to an increased possibility of a high, potentially toxic, exposure to Al and Li during pregnancy. In addition, a larger possibility of a high, potentially beneficial, exposure to Zn could occur during pregnancy in controls. Finally, we found decisive evidence for an average increase of Hg in 5-year-old ASD children compared to only weak evidence for controls. This is concordant with previous research showing an impaired ability for eliminating Hg in the ASD group.

Association between heavy metals exposure (cadmium, lead, arsenic, mercury) and child autistic disorder: a systematic review and meta-analysis

Background

Studies have found that toxic heavy metals exposure could induce the generation of reactive oxygen species (ROS), and is of epigenetic effect, which might be associated with the occurrence of Autistic Disorder (ASD). This systematic review and meta-analysis aims to elucidate the association between exposure to 4 heavy metals, cadmium (Cd), lead (Pb), arsenic(As), and mercury (Hg), and the occurrence of ASD in children.

Methods

We searched PubMed, Web of Science, Embase, and Cochrane Library, from their inception to October 2022, for epidemiological investigations that explore the association between exposure to Cd, Pb, As, or Hg and the occurrence of child ASD.

Results

A total of 53 studies were included, involving 5,054 individuals aged less than 18 (2,533 ASD patients and 2,521 healthy controls). Compared with the healthy controls, in hair and blood tests, concentrations of the 4 heavy metals were significantly higher in the ASD group than in the healthy control group, and the differences in Pb, arsenic and Hg were statistically significant (P < 0.05). In the urine test, concentrations of arsenic and Hg were significantly higher in the ASD group than in the healthy control group (P < 0.05), while the results of Cd and Pb were opposite to those of arsenic and Hg (P > 0.05). Subgroup analysis for geographic regions showed that ASD patients in Asia and Europe had higher concentrations of the 4 heavy metals, compared with the healthy controls, in which the differences in Pb, arsenic, and Hg were statistically significant (P < 0.05), while in North America, the healthy controls had higher Cd, arsenic, and Hg concentrations (P > 0.05).

Conclusion

Compared with the healthy control group, the ASD group had higher concentrations of Cd, Pb, arsenic, and Hg. These 4 heavy metals play different roles in the occurrence and progression of ASD. Moreover, there is significant heterogeneity among the included studies due to controversies about the study results among different countries and regions and different sources of detection materials. The results of this study firmly support the policies to limit heavy metals exposure, especially among pregnant women and young children, so as to help reduce the incidence of ASD.

Why Turkish Parents Refuse Childhood Vaccination? A Qualitative Study

BACKGROUND

Anti-vaccination is spreading among parents. In 2017, 23000 families in Turkey refused vaccinations for their children. Meanwhile an increase in infectious diseases was observed, which might be caused by vaccination rejection. The reasons why families do not vaccinate their children may be very different, such as side effects, or advocation for "healthy life" by gurus. However, the real reasons for vaccine refusal are unknown. Our aim is to determine the reasons for anti-vaccination in Turkey.

METHODS

In order to reveal the real reasons for not taking the vaccine, we planned to conduct interviews with the representatives of the vaccine rejection group using qualitative research methodology with the "grounded theory" method. We searched some anti-vaccination blogs to find candidates for interviews. Within the scope of our study, parental concerns about vaccinations were classified by analyzing the data obtained from semi-structured questions and interviews recorded with voice recorders in face-to-face interviews with 21 parents in 13 cities of Turkey.

RESULTS

The obtained findings were classified under the headings of ''mistrust'', ''vaccine efficacy-importance'', ''decision-making processes - bases'', and ''law-ethics''. Mistrust was the main theme, almost singularly, as the most important reason for vaccine rejection. The salient reasons for mistrusts were: Companies which produce vaccines especially international companies because of conspiratory beliefs; health authorities, because of the belief about non-transparency in epidemiologic data, immunization council etc. and healthcare professionals, because of their non-communicative and non-concerned attitude.

CONCLUSION

Mistrust is hard to overcome. The beliefs of the patients cannot be easily changed. As a result of our study, we made some recommendations for health authorities, healthcare professionals, companies and other related stakeholders.

The role of environmental trace element toxicants on autism: A medical biogeochemistry perspective

Since genetic factors alone cannot explain most cases of Autism, the environmental factors are worth investigating as they play an essential role in the development of some cases of Autism. This research is a review paper that aims to clarify the role of the macro elements (MEs), Trace elements (TEs) and ultra-trace elements (UTEs) on human health if they are greater or less than the normal range. Aluminium (Al), cadmium Cd), lead (Pb), chromium (Cr), zinc (Zn), copper (Cu), nickel (Ni), arsenic (As), mercury (Hg), manganese (Mn), and iron (Fe) have been reviewed. Exposure to toxicants has a chemical effect that may ultimately lead to autism spectrum disorder (ASD). The Cr, As and Al are found in high concentrations in the blood of an autistic child when compared to normal child reference values. The toxic metals, particularly aluminium, are primarily responsible for difficulties in socialization and language skills disabilities. Zinc and copper are important elements in regulating the gene expression of metallothioneins (MTs), and zinc deficiency may be a risk factor for ASD pathogenesis. Autistics frequently have zinc deficiency combined with copper excess; as part of the treatment protocol, it is critical to monitor zinc and copper levels in autistic people, particularly those with zinc deficiency. Zinc deficiency is linked to epileptic seizures, which are common in autistic patients. Higher serum manganese and copper significantly characterize people who have ASD. Autistic children have significantly decreased lead and cadmium in urine, whereas they have significantly higher urine Cr. A higher level of As and Hg was found in the ASD individual's blood.

Prenatal low-dose methylmercury exposure causes premature neuronal differentiation and autism-like behaviors in a rodent model

Aberrant neurodevelopment is a core deficit of autism spectrum disorder (ASD). Here we ask whether a non-genetic factor, prenatal exposure to the environmental pollutant methylmercury (MeHg), is a contributing factor in ASD onset. We showed that adult mice prenatally exposed to non-apoptotic MeHg exhibited key ASD characteristics, including impaired communication, reduced sociability, and increased restrictive repetitive behaviors, whereas in the embryonic cortex, prenatal MeHg exposure caused premature neuronal differentiation. Further single-cell RNA sequencing (scRNA-seq) analysis disclosed that prenatal exposure to MeHg resulted in cortical radial glial precursors (RGPs) favoring asymmetric differentiation to directly generate cortical neurons, omitting the intermediate progenitor stage. In addition, MeHg exposure in cultured RGPs increased CREB phosphorylation and enhanced the interaction between CREB and CREB binding protein (CBP). Intriguingly, metformin, an FDA-approved drug, can reverse MeHg-induced premature neuronal differentiation via CREB/CBP repulsion. These findings provide insights into ASD etiology, its underlying mechanism, and a potential therapeutic strategy.

The combined effect between BDNF genetic polymorphisms and exposure to metals on the risk of Chinese dyslexia

BDNF gene has been implicated in the development of cognition and language. Meanwhile, exposure to metals might interact with BDNF gene to increase the risk of neurodevelopmental disorders. The present study aimed to explore the association between BDNF genetic polymorphisms and dyslexic risk and examine whether BDNF polymorphisms would interact with metal exposures, jointly contributing to dyslexia. Among a case-control study composed of 238 children with dyslexia and 228 healthy controls, the BDNF genetic polymorphisms were genotyped by the Sequenom MassARRAY system, and the exposure to eight metals, such as lead (Pb), mercury (Hg) and copper (Cu), were measured using an inductively coupled plasma-mass spectrometer (ICP-MS). Multivariable logistic regression models were used to assess the adjusted odds ratios (ORs) and 95% confidence interval (CI) of dyslexia. After multivariate adjustment, significant associations of dyslexic risk with rs6265 polymorphisms of the BDNF gene were observed (OR = 1.99; 95% CI: 1.15-3.44). Furthermore, exposure to Cu could interact with rs6265 to increase the risk of dyslexia (P interaction = 0.045). High-Cu children with the rs6265 TT genotype were more likely to have dyslexia compared with low-Cu children carrying CC + CT genotypes (OR = 3.19; 95% CI: 1.38-7.39). The findings of this study suggested that the polymorphism of rs6265 in BDNF gene could interact with Cu exposure to increase the occurrence of dyslexia.

Exposure to multiple metals and the risk of dyslexia - A case control study in Shantou, China

Environmental heavy metal exposure has been considered to be the risk factor for neurodevelopmental disorders in children. However, the available data on the associations between multiple metals exposure and the risk of dyslexia in China are limited. The purpose of our study was to examine the associations between urinary metal concentrations and Chinese dyslexia risk. A total of 56 Chinese dyslexics and 60 typically developing children were recruited. The urinary concentration of 13 metals were measured by inductively coupled plasma-mass spectrometer (ICP-MS). Binary logistic regression and the Probit extension of Bayesian kernel machine regression (BKMR-P) were used to explore the associations between multiple metal exposure and the risk of Chinese dyslexia. Our results indicated that Co, Zn and Pb were significantly associated with Chinese dyslexia in the multiple-metal exposure model. After adjusting the covariates, a positive association was observed between Pb and the risk of Chinese dyslexia, with the odds ratio (OR) in the highest quartiles of 6.81 (95%CI: 1.07-43.19; p-trend = 0.024). Co and Zn were negatively associated with the risk of Chinese dyslexia. Compared to the lowest quartile, the ORs of Co and Zn in the highest quartile are 0.13 (95%CI: 0.02-0.72; p-trend = 0.026) and 0.18 (95%CI: 0.04-0.88; p-trend = 0.038), respectively. In addition, BKMR-P analysis indicated that with the cumulative level across Co, Zn and Pb increased, the risk of Chinese dyslexia gradually declined and then rebounded, albeit non-significantly, and Pb was the major contributor in this association. In general, the urinary concentrations of Co, Zn and Pb were significantly associated with Chinese dyslexia. More prospective studies are needed to confirm the health effects of multiple metals exposure in children with Chinese dyslexia.

Vegetable oil-based nanoemulsions for the preservation of muscle foods: A systematic review and meta-analysis

This systematic review and meta-analysis quantified the effects of various vegetable oil-based nanoemulsion (NE) formulations on muscle foods' microbial and chemical quality by estimating the weighted overall response ratio (R*). Treatment of muscle foods with NE formulations reduced the growth rates of total mesophilic bacteria, total psychrophilic bacteria, lactic acid bacteria, and Enterobacteriaceae by 26.2% (R*=0.738), 19% (R*=0.810), 44.7% (R*=0.553), and 31.8% (R*=0.682) during the storage period, respectively. Moreover, the NE formulations retarded the increasing rates of volatile basic-nitrogen content, lipid and protein oxidation, and lipid hydrolysis by 41.4% (R*=0.586), 34% (R*=0.660), 55% (R*=0.450), and 37.1% (R*=0.629), respectively. The NE formulations prepared from safflower, olive, canola, and sunflower oil were more effective than the other vegetable oils to control microbial growth and slow down chemical changes in muscle foods. The combination of nanoemulsions (NEs) and essential oils (EOs) was more efficient than NEs to preserve muscle foods. Packaging NE-treated muscle foods under anaerobic conditions provided better control of microbial growth and chemical changes than packaging under aerobic conditions. Consequently, a combination of vegetable oil-based NEs and EOs followed by anaerobic packaging is the most effective treatment to improve the quality of muscle foods.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2057415 .

Prenatal Mercury Exposure and Neurodevelopment up to the Age of 5 Years: A Systematic Review

Neurodevelopmental delays can interfere with children’s engagement with the world and further development, and may have negative consequences into adulthood. Mercury is highly toxic and may negatively influence neurodevelopment because it can freely cross the placenta and accumulate in the fetal brain. We searched four publication databases (Embase, PsycINFO, PubMed/MEDLINE, Scopus) for studies examining the relationship between early life mercury exposure and scores on neurodevelopmental performance measures in children aged 0 to 5 years old. Study quality was assessed using the National Institutes of Health (NIH) Quality Assessment Tool. Thirty-two prospective studies were included in the review. Neurodevelopmental performance was measured using 23 different scales, most commonly the Bayley Scales of Infant and Toddler Development (BSID). In most cases, the evidence for an association between mercury and neurodevelopment was weak. There did not appear to be exceptions for particular childhood ages, outcome scales, or mercury levels. The small number of results to the contrary were more likely to be studies which did not meet our high-quality criteria, and could be a consequence of multiple testing, selection bias, or incomplete confounder adjustment. Based on current evidence, dietary mercury exposure during pregnancy is unlikely to be a risk factor for low neurodevelopmental functioning in early childhood.

Uma revisão de escopo de revisões sistemáticas sobre exposição humana ao mercúrio

Resumo: Introdução: a promulgação da Convenção de Minamata no Brasil em 2018 incentivou o cumprimento dos seus objetivos em reduzir o uso e a poluição por mercúrio. Objetivo: caracterizar a produção científica sobre exposição humana ao mercúrio e identificar lacunas de conhecimento a fim de subsidiar a tomada de decisão em saúde. Métodos: revisão de escopo de revisões sistemáticas e metanálises, sem restrição de idioma ou data de publicação, utilizando as bases PubMed, BVS e Cochrane Library. Resultados: 71 estudos atenderam aos critérios de elegibilidade, com 40 revisões sistemáticas, 30 metanálises e 1 overview. Amálgama dentário e contaminação alimentar e ambiental por atividades que utilizam mercúrio foram as fontes de exposição mais mencionadas. Os temas mais estudados contaram com transtornos mentais e comportamentais, assim como uso de biomarcadores e testes neurocomportamentais relacionados à exposição ao mercúrio. Discussão: lacunas como a exposição ocupacional ao mercúrio, uso em práticas tradicionais e em cosméticos apontam para a necessidade de mais estudos. As revisões identificadas podem oferecer subsídios para sínteses de evidências e protocolos de atenção à saúde de populações expostas, assim como para a elaboração de políticas públicas que visem o controle do uso e da exposição ao mercúrio.

Association of autism with toxic metals: A systematic review of case-control studies

Environmental factors have been associated with the etiology of autism spectrum disorder ASD in recent times. The involvement of toxic metals in the generation of reactive oxygen species and their epigenetics effects have been implicated in ASD. This systemic review examines the association of toxic metals with autism in children. A systematic literature search was performed in scientific databases such as PubMed, Google scholar, and Scopus. Case-control studies evaluating toxic metal levels in different tissues of ASD children and comparing them to healthy children (control group) were identified. The Newcastle-Ottawa Scale was used to evaluate the risk of bias of the included studies. Six case-control studies with 425 study subjects met our inclusion criteria. A total of four studies indicated higher levels of As, Pb, Hg, Cd, Al, Sn, Sb, Ba, TI, W, and Zr in whole blood, RBC, in whole blood, RBC, and hair samples of children with autism compared with control suggestive of a greater toxic metal exposure (immediate and long-term). Three studies identified significantly higher concentrations of Cd, Pb and Hg in urine and hair samples of autistic children compared to control suggesting decreased excretion and possible high body burden of these metals. The findings from this review demonstrate that high levels of toxic metals are associated with ASD, therefore, critical care is necessary to reduce body burden of these metals in children with ASD as a major therapeutic strategy.

Molecular Mechanisms of Aberrant Neuroplasticity in Autism Spectrum Disorders (Review)

This review presents the analysis and systematization of modern data on the molecular mechanisms of autism spectrum disorders (ASD) development. Polyetiology and the multifactorial nature of ASD have been proved. The attempt has been made to jointly review and systematize current hypotheses of ASD pathogenesis at the molecular level from the standpoint of aberrant brain plasticity. The mechanism of glutamate excitotoxicity formation, the effect of imbalance of neuroactive amino acids and their derivatives, neurotransmitters, and hormones on the ASD formation have been considered in detail. The strengths and weaknesses of the proposed hypotheses have been analyzed from the standpoint of evidence-based medicine. The conclusion has been drawn on the leading role of glutamate excitotoxicity as a biochemical mechanism of aberrant neuroplasticity accompanied by oxidative stress and mitochondrial dysfunction. The mechanism of aberrant neuroplasticity has also been traced at the critical moments of the nervous system development taking into account the influence of various factors of the internal and external environment. New approaches to searching for ASD molecular markers have been considered.

Trace elements in children with autism spectrum disorder: A meta-analysis based on case-control studies

Autism spectrum disorder (ASD) is a common childhood neurodevelopmental disorder that may be related to trace elements. However, reports on the relationship between them are still inconsistent. In this article, we conducted a meta-analysis on this issue. We searched the PubMed, EMBASE, and Cochrane databases as of November 15, 2019. A random-effects model was used, and subgroups of studies were analyzed using samples of different measurements. Twenty-two original articles were identified (18 trace elements, including a total of 1014 children with ASD and 999 healthy controls). In autistic children, the overall levels of barium (Ba), mercury (Hg), lithium (Li), and lead (Pb) were higher. There were significant differences in the levels of copper (Cu) in the hair and serum between autistic children and the control group. The levels of Hg, Li, Pb and selenium (Se) in the hair of autistic children were higher than those of healthy children, while the levels of zinc (Zn) in the blood were lower. Excessive exposure to toxic heavy metals and inadequate intake of essential metal elements may be associated with ASD. Preventing excessive exposure to toxic metals and correcting poor dietary behaviors may be beneficial for the prevention and treatment of the disease.

Association Between Gestational Exposure to Toxicants and Autistic Behaviors Using Bayesian Quantile Regression

Autism spectrum disorder, which is characterized by impaired social communication and stereotypic behaviors, affects 1%-2% of children. Although prenatal exposure to toxicants has been associated with autistic behaviors, most studies have been focused on shifts in mean behavior scores. We used Bayesian quantile regression to assess the associations between log2-transformed toxicant concentrations and autistic behaviors across the distribution of behaviors. We used data from the Maternal-Infant Research on Environmental Chemicals study, a pan-Canadian cohort (2008-2011). We measured metal, pesticide, polychlorinated biphenyl, phthalate, bisphenol-A, and triclosan concentrations in blood or urine samples collected during the first trimester of pregnancy. Using the Social Responsiveness Scale (SRS), in which higher scores denote more autistic-like behaviors, autistic behaviors were assessed in 478 children aged 3-4 years old. Lead, cadmium, and most phthalate metabolites were associated with mild increases in SRS scores at the 90th percentile of the SRS distribution. Manganese and some pesticides were associated with mild decreases in SRS scores at the 90th percentile of the SRS distribution. We identified several monotonic trends in which associations increased in magnitude from the bottom to the top of the SRS distribution. These results suggest that quantile regression can reveal nuanced relationships and, thus, should be more widely used by epidemiologists.

Autism spectrum disorder: Trace elements imbalances and the pathogenesis and severity of autistic symptoms

The identification of biomarkers as diagnostic tools and predictors of response to treatment of neurological developmental disorders (NDD) such as schizophrenia (SZ), attention deficit hyperactivity disorder (ADHD), or autism spectrum disorder (ASD), still remains an important challenge for clinical medicine. Metallomic profiles of ASD patients cover, besides essential elements such as cobalt, chromium, copper, iron, manganese, molybdenum, zinc, selenium, also toxic metals burden of: aluminum, arsenic, mercury, lead, beryllium, nickel, cadmium. Performed studies indicate that children with ASD present a reduced ability of eliminating toxic metals, which leads to these metals' accumulation and aggravation of autistic symptoms. Extensive metallomic studies allow a better understanding of the importance of trace elements as environmental factors in the pathogenesis of ASD. Even though a mineral imbalance is a fact in ASD, we are still expecting relevant tests and the elaboration of reference levels of trace elements as potential biomarkers useful in diagnosis, prevention, and treatment of ASD.

Connecting inorganic mercury and lead measurements in blood to dietary sources of exposure that may impact child development

Pre-natal and post-natal chemical exposures and co-exposures from a variety of sources including contaminated air, water, soil, and food are common and associated with poorer birth and child health outcomes. Poor diet is a contributing factor in the development of child behavioral disorders. Child behavior and learning can be adversely impacted when gene expression is altered by dietary transcription factors such as zinc insufficiency or deficiency or by exposure to toxic substances permitted in our food supply such as mercury, lead, or organophosphate pesticide residue. Children with autism spectrum disorder and attention deficit hyperactivity disorders exhibit decreased or impaired PON1 gene activity which is needed by the body to metabolize and excrete neurotoxic organophosphate pesticides. In this current review we present an updated macroepigenetic model that explains how dietary inorganic mercury and lead exposures from unhealthy diet may lead to elevated blood mercury and/or lead levels and the development of symptoms associated with the autism and attention deficit-hyperactivity disorders. PON1 gene activity may be suppressed by inadequate dietary calcium, selenium, and fatty acid intake or exposures to lead or mercury. The model may assist clinicians in diagnosing and treating the symptoms associated with these childhood neurodevelopmental disorders. Recommendations for future research are provided based on the updated model and review of recently published literature.

Associations of Metabolic Genes (GSTT1, GSTP1, GSTM1) and Blood Mercury Concentrations Differ in Jamaican Children with and without Autism Spectrum Disorder

We investigated interactive roles of three metabolic glutathione S-transferase (GST) genes (GSTP1, GSTT1, and GSTM1) and autism spectrum disorder (ASD) status in relation to blood Hg concentrations (BHC) of Jamaican children. We used data from 266 children (2-8 years) with ASD and their 1:1 age- and sex-matched typically developing (TD) controls. After adjusting General Linear Models for child’s age, socioeconomic status, consumption of leafy vegetables, fried plantain, canned fish, and the interaction between GSTP1 and GSTT1, we found significant interactions between GSTP1 and ASD status in relation to BHC either in a co-dominant or dominant genetic model for GSTP1(P < 0.001, P = 0.007, respectively). In the co-dominant model for the Ile105Val GSTP1 polymorphism, geometric mean (GM) BHC in ASD cases with genotype Ile/Ile were significantly higher than in cases with the Ile/Val genotype (0.73 vs. 0.48 µg/L, P = 0.01). In contrast, in TD controls with the Ile/Val genotype GM BHC were significantly higher than in those with the Ile/Ile genotype (0.72 vs. 0.49 µg/L, P = 0.03) or the Val/Val genotype (0.72 vs. 0.51 µg/L, P = 0.04). Although our findings are consistent with the role of GSTP1 in detoxification of Hg, replication in other populations is warranted.

Role of metallic pollutants in neurodegeneration: effects of aluminum, lead, mercury, and arsenic in mediating brain impairment events and autism spectrum disorder

Autism spectrum disorder (ASD) is a developmental disorder of the brain characterized by shortfall in the social portfolio of an individual and abbreviated interactive and communication aspects rendering stereotypical behavior and pitfalls in a child's memory, thinking, and learning capabilities. The incidence of ASD has accelerated since the past decade, portraying environment as one of the primary assets, comprising of metallic components aiming to curb the neurodevelopmental pathways in an individual. Many regulations like Clean Air Act and critical steps taken by countries all over the globe, like Sweden and the USA, have rendered the necessity to study the effects of environmental metallic components on ASD progression. The review focuses on the primary metallic components present in the environment (aluminum, lead, mercury, and arsenic), responsible for accelerating ASD symptoms by a set of general mechanisms like oxidative stress reduction, glycolysis suppression, microglial activation, and metalloprotein disruption, resulting in apoptotic signaling, neurotoxic effects, and neuroinflammatory responses. The effect of these metals can be retarded by certain protective strategies like chelation, dietary correction, certain agents (curcumin, mangiferin, selenium), and detoxification enhancement, which can necessarily halt the neurodegenerative effects.

Environmental influence on neurodevelopmental disorders: Potential association of heavy metal exposure and autism

Environmental factors have been severally established to play major roles in the pathogenesis of neurodevelopmental disorders including autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder that is associated with symptoms that reduce the quality of life of affected individuals such as social interaction deficit, cognitive impairment, intellectual disabilities, restricted and repetitive behavioural patterns. ASD pathogenesis has been associated with environmental and genetic factors that alter physiologic processes during development. Here, we review literatures highlighting the environmental impact on neurodevelopmental disorders, and mechanisms by which environmental toxins may influence neurodevelopment. Furthermore, this review discusses reports highlighting neurotoxic metals (specifically, lead, mercury, cadmium, nickel and manganese) as environmental risk factors in the aetiology of ASD. This work, thus suggests that improving the environment could be vital in the management of ASD.

The status of chemical elements in the blood plasma of children with autism spectrum disorder in Tunisia: a case-control study

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders defined by a deficit in social interactions and the presence of restricted and stereotypical behaviors or interests. The etiologies of autism remain mostly unknown. Many genetic and environmental factors have been suspected. Among these environmental factors, exposure to several chemical elements has been previously studied. The purpose of this study was to compare the levels of trace elements in the blood plasma of children with ASD with typically developed children (TDC). The participants in this study consisted of 89 children with ASD (14 girls and 74 boys) and 70 TD children (29 girls and 41 boys). The levels of 33 chemical elements have been analyzed by inductively coupled plasma spectrometry (ICP-MS). We detected significant differences in the levels of eight elements between the two groups, among which there were three rare earth elements (REEs): Eu, Pr, and Sc (p = 0.000, p = 0.023, and p < 0.001 respectively); four heavy metals: Bi, Tl, Ti, and V (p = 0.004, p < 0.001, p = 0.001, and p = 0.001 respectively); and one essential element: Cu (p = 0.043). Children with ASD had higher levels of Er, Pr, Sc, Bi, Tl, Ti, and V, and lower levels of Cu in comparison with the TD group. The children exposed to passive smoking had lower levels of lead (Pb) compared with children without exposure (p = 0.018). Four elements (Cr, Er, Dy, and Pr) were negatively correlated to the severity of ASD. The level of Cu was significantly associated with autistic children's behavior (p = 0.014). These results suggest that children with ASD might have abnormal plasma levels of certain chemical elements (including Er, Pr, Sc, Bi, Tl, Ti, and V, and Cu), and some of these elements might be associated with certain clinical features.

Effect of dietary anthocyanins on biomarkers of glycemic control and glucose metabolism: A systematic review and meta-analysis of randomized clinical trials

Anthocyanins, as natural food colorants, are bioactive substances with several health advantages. In this research, the effects of dietary anthocyanins on biomarkers of glycemic control and glucose metabolism was evaluated through a meta-analysis. The results revealed a significant reduction in levels of fasting blood sugar (FBS; -2.70 mg/dl, 95% CI: -4.70 to -1.31; P < 0.001), 2-h postprandial glucose (2-h PPG; -11.1 mg/dl, 95% CI: -18.7 to -3.48; P = 0.004), glycated hemoglobin (HbA1c; -11.1 mg/dl, 95% CI: -18.7 to -3.48; P = 0.004), homeostasis model assessment of insulin resistance (HOMA-IR; -0.54, 95% CI: -0.94 to -0.14; P = 0.008), resistin (-1.23 µg/l, 95% CI: -2.40 to -0.05; P = 0.041), and plasminogen activator inhibitor-1 (PAI-1; -5.09 µg/l, 95% CI: -9.45 to -0.73; P = 0.022) following administration of anthocyanins, whilst changes in the levels of fasting insulin (0.33 mU/l, 95% CI: -0.18 to 0.85; P = 0.207) and C-peptide (-0.02 µg/l, 95 %CI: -0.20 to 0.16; P = 0.816) was not statistically significant. Consumption of anthocyanins for >8 weeks and at doses >300 mg/day significantly reduced levels of FBS, 2-h PPG, HbA1c, and HOMA-IR. Moreover, anthocyanins administration reduced the levels of FBS, 2-h PPG, HbA1c, and HOMA-IR in type 2 diabetic subjects and HOMA-IR in overweight/obese individuals. Overall, dietary anthocyanins can be used as an adjuvant therapy to improve biomarkers of glycemic control and glucose metabolism specially in diabetic subjects.

Evidence-based umbrella review of 162 peripheral biomarkers for major mental disorders

The literature on non-genetic peripheral biomarkers for major mental disorders is broad, with conflicting results. An umbrella review of meta-analyses of non-genetic peripheral biomarkers for Alzheimer's disease, autism spectrum disorder, bipolar disorder (BD), major depressive disorder, and schizophrenia, including first-episode psychosis. We included meta-analyses that compared alterations in peripheral biomarkers between participants with mental disorders to controls (i.e., between-group meta-analyses) and that assessed biomarkers after treatment (i.e., within-group meta-analyses). Evidence for association was hierarchically graded using a priori defined criteria against several biases. The Assessment of Multiple Systematic Reviews (AMSTAR) instrument was used to investigate study quality. 1161 references were screened. 110 met inclusion criteria, relating to 359 meta-analytic estimates and 733,316 measurements, on 162 different biomarkers. Only two estimates met a priori defined criteria for convincing evidence (elevated awakening cortisol levels in euthymic BD participants relative to controls and decreased pyridoxal levels in participants with schizophrenia relative to controls). Of 42 estimates which met criteria for highly suggestive evidence only five biomarker aberrations occurred in more than one disorder. Only 15 meta-analyses had a power >0.8 to detect a small effect size, and most (81.9%) meta-analyses had high heterogeneity. Although some associations met criteria for either convincing or highly suggestive evidence, overall the vast literature of peripheral biomarkers for major mental disorders is affected by bias and is underpowered. No convincing evidence supported the existence of a trans-diagnostic biomarker. Adequately powered and methodologically sound future large collaborative studies are warranted.

Neurotoxicity by mercury is not associated with autism spectrum disorders in Spanish children

Background

The pathophysiological etiologies related with the development of Autism Spectrum Disorders (ASD) remain controversial. Different authors have studied neurotoxins such as mercury (Hg) and their relationship with ADS. The objective of this study was to assess the levels of Hg in hair in a group of ASD children (chronic exposure) and in urinary excretion (acute exposure), in comparison to a healthy group.

Methods

A case-control study was conducted in Spanish children. We compared 54 ASD children (aged 2–6) with no other associated pathology to a normally-developing control group (54 subjects).

Results

There were no differences in urine (p:0.631) and hair (p:1.000) samples percentages below the limits of detection between the control and the ASD groups, and also between patients in the regression ASD subgroup (AMR) (p:0.08) and the non-regression ASD subgroup (ANMR) (p:0.705). When the analysis was adjusted for age and sex, the differences between Hg levels maintained not significant. There were no correlations between Hg concentrations in the ASD group as a whole (p: 0.739), or when they were subdivided into ASD-AMR (p: 0.739) and ASD-ANMR (p: 0.363).

Conclusions

The present study shows no evidence in our geographical area to support an association between mercury neurotoxicity and the etiopathogenesis of ASD.

Impact of dietary anthocyanins on systemic and vascular inflammation: Systematic review and meta-analysis on randomised clinical trials

Anthocyanins are natural bioactive compounds that have several health benefits. This systematic review and meta-analysis assessed the impact of dietary anthocyanins on markers of systemic and vascular inflammation. Meta-analysis of 32 randomised controlled trials indicated that dietary anthocyanins significantly decreased levels of C-reactive protein (CRP; -0.33 mg/l, 95% CI: -0.55 to -0.11, P = 0.003), interleukin-6 (IL-6; -0.41 ρg/ml, 95% CI: -0.70 to -0.13, P = 0.004), tumor necrosis factor-alpha (TNF-α; -0.64 ρg/ml, 95% CI: -1.18 to -0.09, P = 0.023), intercellular adhesion molecule-1 (-52.4 ng/ml, 95% CI: -85.7 to -19.1, P = 0.002), and vascular adhesion molecule-1 (VCAM-1; -49.6 ng/ml, 95% CI: -72.7 to -26.5, P < 0.001) while adiponectin level was significantly increased (0.75 μg/ml, 95% CI: 0.23 to 1.26, P = 0.004). The levels of interleukin-1β (IL-1β; -0.45 ρg/ml, 95% CI: -3.77 to 2.88, P = 0.793) and P-selectin (-6.98 ng/ml, 95% CI: -18.1 to 4.15, P = 0.219) did not significantly change. Subgroup analyses showed that administration of higher doses of anthocyanins (>300 mg/day) significantly decreased levels of CRP, IL-6, TNF-α, and VCAM-1. The results indicate that dietary anthocyanins reduce the levels of systemic and vascular inflammation in the subjects.

Environmental risk factors and biomarkers for autism spectrum disorder: an umbrella review of the evidence

BACKGROUND

Numerous studies have identified potential risk factors and biomarkers for autism spectrum disorder. We aimed to study the strength and validity of the suggested environmental risk factors or biomarkers of autism spectrum disorder.

METHODS

We did an umbrella review and systematically appraised the relevant meta-analyses of observational studies. We searched PubMed, Embase, and the Cochrane Database of Systematic Reviews for papers published between database inception and Oct 17, 2018, and screened the reference list of relevant articles. We obtained the summary effect, 95% CI, heterogeneity, and 95% prediction intervals. We examined small study effects and excess significance. We did analyses under credibility ceilings. This review is registered with PROSPERO, number CRD42018091704.

FINDINGS

46 eligible articles yielded data on 67 environmental risk factors (544 212 cases, 81 708 787 individuals) and 52 biomarkers (15 614 cases, 15 433 controls). Evidence of association was convincing for maternal age of 35 years or over (relative risk [RR] 1·31, 95% CI 1·18-1·45), maternal chronic hypertension (odds ratio [OR] 1·48, 1·29-1·70), maternal gestational hypertension (OR 1·37, 1·21-1·54), maternal overweight before or during pregnancy (RR 1·28, 1·19-1·36), pre-eclampsia (RR 1·32, 1·20-1·45), prepregnancy maternal antidepressant use (RR 1·48, 1·29-1·71), and maternal selective serotonin reuptake inhibitor (SSRI) use during pregnancy (OR 1·84, 1·60-2·11). Only two associations, maternal overweight before or during pregnancy and SSRI use during pregnancy, retained their high level of evidence under subset sensitivity analyses. Evidence from biomarkers was scarce, being supported by p values close to the significance threshold and too few cases.

INTERPRETATION

Convincing evidence suggests that maternal factors, such as age and features of metabolic syndrome, are associated with risk of autism spectrum disorder. Although SSRI use during pregnancy was also associated with such risk when exposed and non-exposed groups were compared, this association could be affected by other confounding factors, considering that prepregnancy maternal antidepressant use was also convincingly associated with higher risk of autism spectrum disorder. Findings from previous studies suggest that one possible confounding factor is underlying maternal psychiatric disorders.

FUNDING

None.

Developmental exposure to mercury chloride impairs social behavior in male offspring dependent on genetic background and maternal autoimmune environment

To date, the connection between inorganic mercury (Hg) and social behavior remains incompletely understood. The aim of this study was to investigate the influence of maternal autoimmunity by inorganic Hg (Hg²⁺) exposure on social behavior of offspring. Wild-type (WT) and immunoglobulin deficient (Ig^-/-) B10.S dams fertilized by male WT B10.S or SJL mice were treated with 50 μM Hg chloride (HgCl₂). Non-pregnant female WT B10.S mice were used to investigate factors regulating HgCl₂-induced autoimmunity to brain. HgCl₂ selectively impaired social behavior in male offspring, but not female offspring from WT B10.S dams × male SJL, in that only male offspring displayed reduced time distribution with the stranger mouse, decreased sniffing to the stranger mouse and increased self-grooming. HgCl₂ did not disrupt social behavior of male or female offspring from WT B10.S dams × male WT B10.S or Ig^-/- B10.S dams × male SJL. The offspring from WT and Ig^-/- B10.S dams × male SJL had equivalent autoimmunity to brain antigens during HgCl₂ exposure, indicating that maternal, but not offspring-derived anti-brain antibodies (Ab) impaired social behavior of the offspring. Non-pregnant WT B10.S mice treated with HgCl₂ had increased anti-brain Ab dependent on increase in CD4 T cell activation and IFNγ signaling to macrophages. IFNγ interaction with macrophages drove B cells and plasma cells to produce IgG. Therefore, HgCl₂ selectively impaired social behavior in males with certain genetic background via maternally derived anti-brain Ab production, thus providing a novel insight into our current understanding of Hg toxicity.

Mercury leads to abnormal red blood cell adhesion to laminin mediated by membrane sulfatides

Exposure to mercury is associated with numerous health problems, affecting different parts of the human body, including the nervous and cardiovascular systems in adults and children; however, the underlying mechanisms are yet to be fully elucidated. We investigated the role of membrane sulfatide on mercuric ion (Hg²⁺) mediated red blood cell (RBC) adhesion to a sub-endothelial matrix protein, laminin, using a microfluidic system that mimics microphysiological flow conditions. We exposed whole blood to mercury (HgCl₂), at a range of concentrations to mimic acute (high dose) and chronic (low dose) exposure, and examined RBC adhesion to immobilized laminin in microchannels at physiological flow conditions. Exposure of RBCs to both acute and chronic levels of Hg²⁺ resulted in elevated adhesive interactions between RBCs and laminin depending on the concentration of HgCl₂ and exposure duration. BCAM-Lu chimer significantly inhibited the adhesion of RBCs that had been treated with 50 μM of HgCl₂ solution for 1 h at 37 °C, while it did not prevent the adhesion of 3 h and 24 h Hg²⁺-treated RBCs. Sulfatide significantly inhibited the adhesion of RBC that had been treated with 50 μM of HgCl₂ solution for 1 h at 37 °C and 0.5 μM of HgCl₂ solution for 24 h at room temperature (RT). We demonstrated that RBC BCAM-Lu and RBC sulfatides bind to immobilized laminin, following exposure of RBCs to mercuric ions. The results of this study are significant considering the potential associations between sulfatides, red blood cells, mercury exposure, and cardiovascular diseases.

Trace element levels are associated with neuroinflammatory markers in children with autistic spectrum disorder

The objective of the present study was to estimate the association between brain inflammatory markers and serum trace element levels as assessed by inductively coupled plasma mass spectrometry at NexION 300D. Leukocyte elastase (LE), α1-proteinase inhibitor (α1-PI) activity, anti-nerve growth factor-antibodies (anti-NGF-Ab), and anti-myelin basic protein-antibodies (anti-MBP-Ab) levels were assessed as inflammatory markers. The obtained data demonstrate that the increase in LE and α1-PI activity is associated with higher serum Cr and Cu levels, respectively. The increase in Anti-NGF-Ab levels was associated with a nearly significant 16% increase in serum Mn levels. Autistic children with high MBP-Ab levels were characterized by 28% higher serum Mn and lower Mg concentration. The results of correlation analysis were generally in agreement with the outcome of group comparisons. Regression analysis demonstrated that serum Mg was significantly negatively associated with LE activity, whereas both serum Fe and V concentrations were characterized by a positive influence on the parameter. In turn, serum Cu was a significant predictor of α1-PI, as well as Cr levels. At the same time, the serum concentrations of Cd and Fe were found to be inversely associated with α1-PI levels. Serum Cd and Mn levels were significant positive predictors of anti-MBP-Ab levels, whereas Mg levels had a negative impact on anti-MBP-Ab values. Generally, the obtained data demonstrate the interrelationship between trace element homeostasis and neuroinflammation in autism. Hypothetically, modulation of trace element status may be used for reduction of neuroinflammatory response, although further studies are required to reveal the underlying mechanisms of the observed associations.

Multiple low-level exposures: Hg interactions with co-occurring neurotoxic substances in early life

All chemical forms of Hg can affect neurodevelopment; however, low levels of organic Hg (methylmercury-MeHg and ethylmercury-EtHg in Thimerosal-containing vaccines, hereafter 'TCV') exposures during early life (pregnancy and lactation) co-occur with other environmental neurotoxic substances. These neurotoxicants may act in parallel, synergistically, or antagonistically to Hg. Nevertheless, the risks of neurotoxicity associated with multiple neuro-toxicants depend on type, time, combinations of exposure, and environmental and/or genetic-associated factors. Neurological developmental disorders, delays in cognition and behavioral outcomes associated with multiple exposures (which include Hg) may show transient or lasting outcomes depending on constitutional and/or environmental factors that can interact to neutralize, aggravate or attenuate these effects; often these studies are challenging to interpret. During pregnancy and lactation, fish-MeHg exposure is frequently confounded with the opposing effects of neuroactive nutrients (in fish) that lead to positive, negative, or no effects on neurobehavioral tests. In infancy, exposures to acute binary mixtures (TCV- EtHg and Al-adjuvants in infant immunizations) are associated with increased risks of tics and other developmental disorders. Despite the certitude that promulgates single environmental neurotoxicants, empirical comparisons of combined exposures indicate that Hg-related outcome is uneven. Hg in combination with other neurotoxic mixtures may elevate risks of neurotoxicity, but these risks arise in circumstances that are not yet predictable. Therefore, to achieve the goals of the Minamata treaty and to safeguard the health of children, low levels of mercury exposure (in any chemical form) needs to be further reduced whether the source is environmental (air- and food-borne) or iatrogenic (pediatric TCVs).

Toxic metal(loid)-based pollutants and their possible role in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction, verbal and non-verbal communication, and stereotypic behaviors. Many studies support a significant relationship between many different environmental factors in ASD etiology. These factors include increased daily exposure to various toxic metal-based environmental pollutants, which represent a cause for concern in public health. This article reviews the most relevant toxic metals, commonly found, environmental pollutants, i.e., lead (Pb), mercury (Hg), aluminum (Al), and the metalloid arsenic (As). Additionally, it discusses how pollutants can be a possible pathogenetic cause of ASD through various mechanisms including neuroinflammation in different regions of the brain, fundamentally occurring through elevation of the proinflammatory profile of cytokines and aberrant expression of nuclear factor kappa B (NF-κB). Due to the worldwide increase in toxic environmental pollution, studies on the role of pollutants in neurodevelopmental disorders, including direct effects on the developing brain and the subjects' genetic susceptibility and polymorphism, are of utmost importance to achieve the best therapeutic approach and preventive strategies.