Effects of genetic polymorphisms on antioxidant status and concentrations of the metals in the blood of riverside Amazonian communities co-exposed to Hg and Pb

Levels and health risk assessment of twenty-one current-use pesticides in urban and riverside waters of the Brazilian Amazon Basin

In Brazil, the favorable weather conditions and abundant land contribute to the thriving agricultural production. Brazilian crops extensively employ pesticides due to their high efficacy, cost-effectiveness, and permissive regulatory framework. However, pesticide use also endangers water resources, animal organisms, and human health. Due to the lack of data on pesticide use in the Amazonas forest-based Brazil, the present study aimed to assess the levels of twenty-one current-use pesticides (CUPs) from five different classes in river waters collected from urban and riverside areas in this region. Moreover, the non-carcinogenic risks associated with water consumption were also characterized. Thirteen CUPs were detected in concentrations above the limit of detection (LOD) in at least one of the water samples, and most pesticides were detected in riverside areas. In contrast, only 18% of the analyzed samples were considered "clean," with only one compound detected. Fenitrothion showed the highest concentration, with a mean value of 4.86 ng/mL (0.30-14.3 ng/mL). Up to 33% of the samples showed levels of fipronil above the LOD, an issue of environmental and human health concern, mainly because of the adverse effects observed in honeybees. Despite this, the human health risk assessment showed a target hazard quotient below one (HQ < 1) in adults for all substances, suggesting that pesticide exposure through water consumption should not mean risk for the riverside populations. Taking into account the large extension of Brazil, as well as its different agricultural practices throughout the country, it would be of great importance to conduct extensive research in other areas. It would help to gain knowledge in this field and to promote eco-friendly alternatives to mitigate pesticide use and, consequently, to reduce their potential adverse effects on human health and the ecosystems.

Genomic investigation on genes related to mercury metabolism in Amazonian indigenous populations

Studies have identified elevated levels of mercury in Amazonian Indigenous individuals, highlighting them as one of the most exposed to risks. In the unique context of the Brazilian Indigenous population, it is crucial to identify genetic variants with clinical significance to better understand vulnerability to mercury and its adverse effects. Currently, there is a lack of research on the broader genomic profile of Indigenous people, particularly those from the Amazon region, concerning mercury contamination. Therefore, the aim of this study was to assess the genomic profile related to the processes of mercury absorption, distribution, metabolism, and excretion in 64 Indigenous individuals from the Brazilian Amazon. We aimed to determine whether these individuals exhibit a higher susceptibility to mercury exposure. Our study identified three high-impact variants (GSTA1 rs1051775, GSTM1 rs1183423000, and rs1241704212), with the latter two showing a higher frequency in the study population compared to global populations. Additionally, we discovered seven new variants with modifier impact and a genomic profile different from the worldwide populations. These genetic variants may predispose the study population to more harmful mercury exposure compared to global populations. As the first study to analyze broader genomics of mercury metabolism pathways in Brazilian Amazonian Amerindians, we emphasize that our research aims to contribute to public policies by utilizing genomic investigation as a method to identify populations with a heightened susceptibility to mercury exposure.

Evaluation of exposure to multiple organic pollutants in riparian communities of the Brazilian Amazon: Screening levels and potential health risks

Organic pollutants are widely distributed in the environment. Due to their physical and chemical characteristics, they tend to be biomagnified in food chains, mainly in aquatic organisms. Therefore, food consumption is a significant route of lifelong exposure. Although the Amazon River basin contains the highest freshwater biodiversity on Earth, there is scarce literature focusing on the levels of organic pollutants in the local population. The present study was aimed at assessing the levels of several environmental pollutants (polycyclic aromatic hydrocarbons, bisphenols, parabens, and benzophenones) in urine samples from riverside communities along the Tapajós and Amazon Rivers in the Brazilian Amazon region. The results show a 100 % detection of naphthalene metabolites (namely, 1-hydroxy-naphthalene (1OH-NAP), 2-hydroxy-naphthalene (2OH-NAP)), with the highest levels belonging to benzylparaben (BzP) (17.3 ng/mL). Gender-specific analysis revealed that women had significantly higher levels of certain PAH metabolites (i.e., 1OH-NAP and 2-hydroxy-fluorene (2OH-FLU)) than men. In turn, most of the evaluated compounds were higher in urine samples from people living near the Amazon River, which presents increased traffic of boats and ships than the Tapajós River. On the other hand, the human health risk assessment suggested that all communities are at risk of suffering non-carcinogenic effects from exposure to PAHs. At the same time, they are also at risk of carcinogenic effects from exposure to benzo[a]pyrene metabolites. Thus, further studies are needed in order to evaluate the potential health effects of exposure to a mixture of these organic pollutants and other contaminants present in the area, such as mercury.

Factors associated with blood mercury concentrations and their interactions with three glutathione S-transferase genes (GSTT1, GSTM1, and GSTP1): an exposure assessment study of typically developing Jamaican children

BACKGROUND

Jamaican soil is abundant in heavy metals including mercury (Hg). Due to availability and ease of access, fish is a traditional dietary component in Jamaica and a significant source of Hg exposure. Mercury is a xenobiotic and known neuro-toxicant that affects children's neurodevelopment. Human glutathione S-transferase (GST) genes, including GSTT1, GSTM1, and GSTP1, affect Hg conjugation and elimination mechanisms.

METHODS

In this exposure assessment study we used data from 375 typically developing (TD) 2-8-year-old Jamaican children to explore the association between environmental Hg exposure, GST genes, and their interaction effects on blood Hg concentrations (BHgCs). We used multivariable general linear models (GLMs).

RESULTS

We identified the child's age, consumption of saltwater fish, canned fish (sardine, mackerel), string beans, grain, and starches (pasta, macaroni, noodles) as the environmental factors significantly associated with BHgCs (all P < 0.05). A significant interaction between consumption of canned fish (sardine, mackerel) and GSTP1 in relation to BHgC using either a co-dominant or recessive genetic model (overall interaction P = 0.01 and P < 0.01, respectively) indicated that consumption of canned fish (sardine, mackerel) was significantly associated with higher mean BHgC only among children with the GSTP1 Ile105Val, Ile/Ile [Ratio of mean Hg (95% CI) = 1.59 (1.09, 2.32), P = 0.02] and Ile/Val [Ratio of mean Hg (95% CI) = 1.46 (1.12, 1.91), P = 0.01] genotypes.

CONCLUSIONS

Since this is the first study from Jamaica to report these findings, replication in other populations is recommended.

Revisiting Genetic Influence on Mercury Exposure and Intoxication in Humans: A Scoping Review

Human intoxication to mercury is a worldwide health problem. In addition to the type and length of exposure, the genetic background plays an important role in mercury poisoning. However, reviews on the genetic influence in mercury toxicity are scarce and not systematic. Therefore, this review aimed to systematically overview the most recent evidence on the genetic influence (using single nucleotide polymorphisms, SNPs) on human mercury poisoning. Three different databases (PubMed/Medline, Web of Science and Scopus) were searched, and 380 studies were found that were published from 2015 to 2022. After applying inclusion/exclusion criteria, 29 studies were selected and data on characteristics (year, country, profile of participants) and results (mercury biomarkers and quantitation, SNPs, main findings) were extracted and analyzed. The largest number of studies was performed in Brazil, mainly involving traditional populations of the Tapajós River basin. Most studies evaluated the influence of the SNPs related to genes of the glutathione system (GST, GPx, etc.), the ATP-binding cassette transporters and the metallothionein proteins. The recent findings regarding other SNPs, such as those of apolipoprotein E and brain-derived neurotrophic factor genes, are also highlighted. The importance of the exposure level is discussed considering the possible biphasic behavior of the genetic modulation phenomena that could explain some SNP associations. Overall, recommendations are provided for future studies based on the analysis obtained in this scoping review.

Association of genetic polymorphisms in detoxifying systems and urinary metal(loid) levels with excess body weight among Spanish children: A proof-of-concept study

Exposure to metal(loid)s during critical developmental windows could result in permanent damage to the target organ system, increasing susceptibility to disease later in life. In view of the fact that metals(loid)s have been shown to work as obesogens, the aim of the present case-control study was to evaluate the modification effect of exposure to metal(loid)s on the association between SNPs in genes involved in metal(loid) detoxification and excess body weight among children. A total of 134 Spanish children aged 6-12 years old were included (88 controls and 46 cases). Seven SNPs (GSTP1 rs1695 and rs1138272; GCLM rs3789453, ATP7B rs1061472, rs732774 and rs1801243; and ABCC2 rs1885301) were genotyped on GSA microchips, and ten metal(loid)s were analysed in urine samples through Inductively coupled plasma mass spectrometry (ICP-MS). Multivariable logistic regressions were conducted to assess the genetic and metal exposures' main association and interaction effects. GSTP1 rs1695 and ATP7B rs1061472 showed significant effects on excess weight increase in those children carrying two copies of the risk G allele and being highly exposed to chromium (ORa = 5.38, p = 0.042, p interaction = 0.028 for rs1695; and ORa = 4.20, p = 0.035, p interaction = 0.012 for rs1061472) and lead (ORa = 7.18, p = 0.027, p interaction = 0.031 for rs1695, and ORa = 3.42, p = 0.062, p interaction = 0.010 for rs1061472). Conversely, GCLM rs3789453 and ATP7B rs1801243 appeared to play a protective role against excess weight in those exposed to copper (ORa = 0.20, p = 0.025, p interaction = 0.074 for rs3789453) and lead (ORa = 0.22, p = 0.092, p interaction = 0.089 for rs1801243). Our findings provide the first proof that interaction effects could exist between genetic variants within GSH and metal transporting systems and exposure to metal(loid)s, on excess body weight among Spanish children.

Impact of DNA repair polymorphisms on DNA instability biomarkers induced by lead (Pb) in workers exposed to the metal

Although the mechanisms of Pb-induced genotoxicity are well established, a wide individual's variation response is seen in biomarkers related to Pb toxicity, despite similar levels of metal exposure. This may be related to intrinsic variations, such as genetic polymorphisms; moreover, very little is known about the impact of genetic variations related to DNA repair system on DNA instability induced by Pb. In this context, the present study aimed to assess the impact of SNPs in enzymes related to DNA repair system on biomarkers related to acute toxicity and DNA damage induced by Pb exposure, in individuals occupationally exposed to the metal. A cross-sectional study was run with 154 adults (males, >18 years) from an automotive batteries' factory, in Brazil. Blood lead levels (BLL) were determined by ICP-MS; biomarkers related to acute toxicity and DNA instability were monitored by the buccal micronucleus cytome (BMNCyt) assay and genotyping of polymorphisms of MLH1 (rs1799977), OGG1 (rs1052133), PARP1 (rs1136410), XPA (rs1800975), XPC (rs2228000) and XRCC1 (rs25487) were performed by TaqMan assays. BLL ranged from 2.0 to 51 μg dL^-1 (mean 20 ± 12 μg dL^-1) and significant associations between BLL and BMNCyt biomarkers related to cellular proliferation and cytokinetic, cell death and DNA damage were observed. Furthermore, SNPs from the OGG1, XPA and XPC genes were able to modulate interactions in nuclear bud formation (NBUDs) and micronucleus (MNi) events. Taken together, our data provide further evidence that polymorphisms related to DNA repair pathways may modulate Pb-induced DNA damage; studies that investigate the association between injuries to genetic material and susceptibilities in the workplace can provide additional information on the etiology of diseases and the determination of environmentally responsive genes.

Global Human Threat: The Potential Synergism between Mercury Intoxication and COVID-19

The COVID-19 pandemic affected billions of people worldwide, and exposure to toxic metals has emerged as an important risk factor for COVID-19 severity. Mercury is currently ranked as the third toxic substance of global concern for human health, and its emissions to the atmosphere have increased globally. Both COVID-19 and mercury exposure present a high prevalence in similar regions: East and Southeast Asia, South America and Sub-Saharan Africa. Since both factors represent a multiorgan threat, a possible synergism could be exacerbating health injuries. Here, we discuss key aspects in mercury intoxication and SARS-CoV-2 infection, describing the similarities shared in clinical manifestations (especially neurological and cardiovascular outcomes), molecular mechanisms (with a hypothesis in the renin-angiotensin system) and genetic susceptibility (mainly by apolipoprotein E, paraoxonase 1 and glutathione family genes). Literature gaps on epidemiological data are also highlighted, considering the coincident prevalence. Furthermore, based on the most recent evidence, we justify and propose a case study of the vulnerable populations of the Brazilian Amazon. An understanding of the possible adverse synergism between these two factors is crucial and urgent for developing future strategies for reducing disparities between developed and underdeveloped/developing countries and the proper management of their vulnerable populations, particularly considering the long-term sequelae of COVID-19.

Exposição ao mercúrio e anemia em crianças e adolescentes de seis comunidades da Amazônia Brasileira

Resumo O mercúrio (Hg) é uma substância tóxica, sendo o consumo de pescados uma das principais fontes de exposição da população. Este artigo visa avaliar a associação entre anemia e exposição ao Hg na população infanto-juvenil de seis comunidades ribeirinhas da Amazônia Brasileira. Realizou-se a análise secundária de dados de estudos seccionais, incluindo 1.318 indivíduos, divididos em dois grupos segundo a influência do garimpo (grupo A sob influência, e grupo B sem influência). Métodos de análise multivariada foram realizados para verificar a associação entre variável de exposição (Hg no cabelo) e anemia, estratificando pelos grupos. Foram observados 348 casos de anemia (27,1%), sendo 206 entre o grupo B e 142 no grupo A. Houve diferença na mediana dos níveis de Hg entre os grupos (A = 12,8µg/g e B = 4,3µg/g, p = 0,01). Foi observada associação entre Hg no cabelo ≥ 6,0µg/g e anemia (OR = 1,38; IC95% = 1,02-1,87), fato que foi magnificado para o grupo A quando realizada estratificação (OR = 2,23; IC95% = 1,28-3,90). O estudo mostrou elevados níveis de Hg, principalmente no grupo A, e que essa substância pode ser um possível fator de risco para anemia. Além disso, as áreas geográficas pareceram modificar esse efeito, apontando para influência de outros fatores, fato que deve ser melhor avaliado.

Mercury Exposure in Munduruku Indigenous Communities from Brazilian Amazon: Methodological Background and an Overview of the Principal Results

The Amazonian indigenous peoples depend on natural resources to live, but human activities' growing impacts threaten their health and livelihoods. Our objectives were to present the principal results of an integrated and multidisciplinary analysis of the health parameters and assess the mercury (Hg) exposure levels in indigenous populations in the Brazilian Amazon. We carried out a cross-sectional study based on a census of three Munduruku indigenous villages (Sawré Muybu, Poxo Muybu, and Sawré Aboy), located in the Sawré Muybu Indigenous Land, between 29 October and 9 November 2019. The investigation included: (i) sociodemographic characterization of the participants; (ii) health assessment; (iii) genetic polymorphism analysis; (iv) hair mercury determination; and (v) fish mercury determination. We used the logistic regression model with conditional Prevalence Ratio (PR), with the respective 95% confidence intervals (CI95%) to explore factors associated with mercury exposure levels ≥6.0 µg/g. A total of 200 participants were interviewed. Mercury levels (197 hair samples) ranged from 1.4 to 23.9 μg/g, with significant differences between the villages (Kruskal-Wallis test: 19.9; p-value < 0.001). On average, the general prevalence of Hg exposure ≥ 6.0 µg/g was 57.9%. For participants ≥12 years old, the Hg exposure ≥6.0 µg/g showed associated with no regular income (PR: 1.3; CI95%: 1.0-1.8), high blood pressure (PR: 1.6; CI95%: 1.3-2.1) and was more prominent in Sawré Aboy village (PR: 1.8; CI95%: 1.3-2.3). For women of childbearing age, the Hg exposure ≥6.0 µg/g was associated with high blood pressure (PR: 1.9; CI95%: 1.2-2.3), with pregnancy (PR: 1.5; CI95%: 1.0-2.1) and was more prominent among residents in Poxo Muybu (PR: 1.9; CI95%: 1.0-3.4) and Sawré Aboy (PR: 2.5; CI95%: 1.4-4.4) villages. Our findings suggest that chronic mercury exposure causes harmful effects to the studied indigenous communities, especially considering vulnerable groups of the population, such as women of childbearing age. Lastly, we propose to stop the illegal mining in these areas and develop a risk management plan that aims to ensure the health, livelihoods, and human rights of the indigenous people from Amazon Basin.

Genetic Polymorphism of Delta Aminolevulinic Acid Dehydratase (ALAD) Gene and Symptoms of Chronic Mercury Exposure in Munduruku Indigenous Children within the Brazilian Amazon

Genetic polymorphisms involved in mercury toxicokinetics and toxicodynamics may be associated with severe mercury toxicity. This study aimed to investigate the impact of an ALAD polymorphism on chronic mercury exposure and the health situation of indigenous children from the Brazilian Amazon. One-hundred-and-three indigenous children (under 15 years old) were included and genotyped (rs1800435) using a TaqMan validated assay. The mean age was 6.6 ± 4.5 years old, 60% were female, 49% presented with anemia, and the mean hair mercury concentration was 7.0 ± 4.5 (1.4-23.9) µg/g, with 49% exceeding the reference limit (≥6.0 µg/g). Only two children were heterozygous ALAD, while the others were all wild type. Minor allele frequency (ALAD G) and heterozygous genotype (ALAD CG) were 1% and 2%, respectively. The two children (12 and 14 years old) with the ALAD polymorphism had mercury levels above the average as well as had neurological symptoms related to chronic mercury exposure, such as visual field alterations, memory deficit, distal neuropathy, and toe amyotrophy. Both children also reported frequent consumption of fish in the diet, at least three times a week. In conclusion, our data confirm that an ALAD polymorphism can contribute to mercury half-life time, harmful effects, and neuropsychological disorders in indigenous children with chronic mercury exposure to gold mining activity.

Erythrocytes as a Model for Heavy Metal-Related Vascular Dysfunction: The Protective Effect of Dietary Components

Heavy metals are toxic environmental pollutants associated with severe ecological and human health risks. Among them is mercury (Hg), widespread in air, soil, and water, due to its peculiar geo-biochemical cycle. The clinical consequences of Hg exposure include neurotoxicity and nephrotoxicity. Furthermore, increased risk for cardiovascular diseases is also reported due to a direct effect on cardiovascular tissues, including endothelial cells, recently identified as important targets for the harmful action of heavy metals. In this review, we will discuss the rationale for the potential use of erythrocytes as a surrogate model to study Hg-related toxicity on the cardiovascular system. The toxic effects of Hg on erythrocytes have been amply investigated in the last few years. Among the observed alterations, phosphatidylserine exposure has been proposed as an underlying mechanism responsible for Hg-induced increased proatherogenic and prothrombotic activity of these cells. Furthermore, following Hg-exposure, a decrease in NOS activity has also been reported, with consequent lowering of NO bioavailability, thus impairing endothelial function. An additional mechanism that may induce a decrease in NO availability is the generation of an oxidative microenvironment. Finally, considering that chronic Hg exposure mainly occurs through contaminated foods, the protective effect of dietary components is also discussed.

Gene Variants Determine Placental Transfer of Perfluoroalkyl Substances (PFAS), Mercury (Hg) and Lead (Pb), and Birth Outcome: Findings From the UmMuKi Bratislava-Vienna Study

Prenatal exposure to perfluoroalkyl substances (PFAS), bisphenol A (BPA), lead (Pb), total mercury (THg), and methylmercury (MeHg) can affect fetal development. Factors influencing placental transfer rate of these toxins are poorly investigated. Whether prenatal exposure to pollutants has an effect on birth weight is incompletely understood. We therefore aimed (1) to determine placental transfer rates of PFAS, BPA, Pb, THg, and MeHg, (2) to analyze relationships between fetal exposure and birth outcome and (3) to analyze gene variants as mediators of placental transfer rates and birth outcome. Two hundred healthy pregnant women and their newborns participated in the study. BPA, 16 PFAS, THg, MeHg, and Pb were determined using HPLCMS/MS (BPA, PFAS), HPLC-CV-ICPMS (MeHg), CV-AFS (THg), and GF-AAS (Pb). Questionnaires and medical records were used to survey exposure sources and birth outcome. 20 single nucleotide polymorphisms and two deletion polymorphisms were determined by real-time PCR from both maternal and newborn blood. Genotype-phenotype associations were analyzed by categorical regression and logistic regression analysis. Specific gene variants were associated with altered placental transfer of PFAS (ALAD Lys59Asn, ABCG2 Gln141Lys), THg (UGT Tyr85Asp, GSTT1del, ABCC1 rs246221) and Pb (GSTP1 Ala114Val). A certain combination of three gene polymorphisms (ABCC1 rs246221, GCLM rs41303970, HFE His63Asp) was over-represented in newborns small for gestational age. 36% of Austrian and 75% of Slovakian mothers had levels exceeding the HBM guidance value I (2 μg/L) of the German HBM Commission for PFOA. 13% of newborns and 39% of women had Ery-Pb levels above 24 μg/kg, an approximation for the BMDL₀₁ of 12 μg/L set by the European Food Safety Authority (EFSA). Our findings point to the need to minimize perinatal exposures to protect fetal health, especially those genetically predisposed to increased transplacental exposure.

Adaptive epigenetic response of glutathione (GSH)-related genes against lead (Pb)-induced toxicity, in individuals chronically exposed to the metal

It is well known that one of the most outstanding adverse effects related to lead (Pb) exposure is oxidative stress; moreover, recent findings suggest that disturbances of the redox status of cells are associated with epigenetic responses, and metabolism of glutathione (GSH) plays an important role in this process. This study aimed to assess Pb exposure on % methylation of GSH-related genes' promoter regions (%CH₃-CpG) and their influence on biomarkers of oxidative stress, in workers exposed to the metal. One hundred nine male workers participated in the study; ICP-MS determined blood lead levels (BLL); biochemical parameters related to redox status, named GSH, glutathione peroxidase (GPX) and glutathione-S-transferase (GST) were quantified by UV/Vis spectrophotometry. Determination of %CH₃-CpG of genes GCLC, GPX1, GSR, and GSTP1 were done by pyrosequencing. Inverse associations were seen between BLL and %CH₃-CpG-GCLC, and %CH₃-CpG-GSTP1. Moreover, metal exposure did not impact GSH, GPX, and GST; however, negative associations were observed between %CH₃-CpG-GPX1 and %CH₃-CpG-GSTP1, and the activities of GPX and GST, respectively. Taken together, our results give further evidence about adaptive epigenetic response to avoid oxidative damage induced by Pb exposure, allowing a better understanding of the molecular mechanisms related to the metal toxicity.

Association Between miR-148a and DNA Methylation Profile in Individuals Exposed to Lead (Pb)

Experimental and epidemiologic studies have shown that lead (Pb) is able to induce epigenetic modifications, such as changes in DNA methylation profiles, in chromatin remodeling, as well as the expression of non-coding RNAs (ncRNAs). However, very little is known about the interactions between microRNAs (miRNAs) expression and DNA methylation status in individuals exposed to the metal. The aim of the present study was to investigate the impact of hsa-miR-148a expression on DNA methylation status, in 85 workers exposed to Pb. Blood and plasma lead levels (BLL and PLL, respectively) were determined by ICP-MS; expression of the miRNA-148a was quantified by RT-qPCR (TaqMan assay) and assessment of the global DNA methylation profile (by measurement of 5-methylcytosine; % 5-mC) was performed by ELISA. An inverse association was seen between miR-148a and % 5-mC DNA, as a function of BLL and PLL (β = −3.7; p = 0.071 and β = −4.1; p = 0.049, respectively) adjusted for age, BMI, smoking, and alcohol consumption. Taken together, our study provides further evidence concerning the interactions between DNA methylation profile and miR-148a, in individuals exposed to Pb.

An overview of the current progress, challenges, and prospects of human biomonitoring and exposome studies

Human Biomonitoring (HB), the process for determining whether and to what extent chemical substances penetrated our bodies, serves as a useful tool to quantify human exposure to pollutants. In cases of nutrition and physiologic status, HB plays a critical role in the identification of excess or deficiency of essential nutrients. In pollutant HB studies, levels of substances measured in body fluids (blood, urine, and breast milk) or tissues (hair, nails or teeth) aid in the identification of potential health risks or associated adverse effects. However, even as a widespread practice in several countries, most HB studies reflect exposure to a single compound or mixtures which are measured at a single time point in lifecycle. On the other hand, throughout an individual's lifespan, the contact with different physical, chemical, and social stressors occurs at varying intensities, differing times and durations. Further, the interaction between stressors and body receptors leads to dynamic responses of the entire biological system including proteome, metabolome, transcriptome, and adductome. Bearing this in mind, a relatively new vision in exposure science, defined as the exposome, is postulated to expand the traditional practice of measuring a single exposure to one or few chemicals at one-time point to an approach that addresses measures of exposure to multiple stressors throughout the lifespan. With the exposome concept, the science of exposure advances to an Environment-Wide Association Perspective, which might exhibit a stronger relationship with good health or disease conditions for an individual (phenotype). Thus, this critical review focused on the current progress of HB and exposome investigations, anticipating some challenges, strategies, and future needs to be taken into account for designing future surveys.

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

Lead (Pb) is an environmental pollutant with a toxicity that is a serious public health problem. The aim of this research was to evaluate the associations between Pb exposure and morphometric, hematological and biochemical parameters, mRNA expression of the P53, SOD1, ALAD, TNF and INF-γ genes, ALAD polymorphisms (db SNP ID: rs1800435) and Intelligence Quotient (IQ) in children from the Colombian Caribbean. Blood lead levels (BLL) were determined in 554 participants between the ages of 5-16 years old, from different places of the Colombian Caribbean. A health survey was given to assess risk factors. Whole blood was used for hematology and plasma employed to analyze markers of hepatic toxicity. Gene expression was quantified from blood mRNA by RT-PCR. The ALAD polymorphism was characterized by PCR-RFLP, and the Kaufman's brief intelligence test was employed to estimate the IQ. The mean BLL was 3.5 ± 0.2 μg/dL. The site of greatest exposure to Pb was Tasajera, a poor fishing community, with an average of 8.9 ± 0.8 μg/dL. Breastfeeding was associated with high BLL. Morphometric characteristics and IQ were negatively correlated with BLL. The blood platelet count and the mean corpuscular hemoglobin concentration showed positive and negative correlations with BLL, respectively. Negative relationships with BLL were observed with the ratios Neutrophils/Eosinophils and Neutrophils/Basophils, whereas for BLL and Neutrophils/Monocytes the association was positive. The associations between morphometric and some hematological parameters with BLL were age- and gender-related. The expression of ALAD, SOD1, INF-γ and P53 mRNA was down-regulated according to the BLL, whereas TNF showed an opposite trend. In short, fishing communities are at a high risk of Pb exposure. This xenobiotic can affect physical development and IQ, as well as hematological parameters, even at low concentrations. In addition, it can regulate the transcription of genes associated with inflammation, apoptosis, cell cycle, heme synthesis, and oxidative stress.

Guarana improves behavior and inflammatory alterations triggered by methylmercury exposure: an in vivo fruit fly and in vitro neural cells study

Methylmercury (MeHg) is a well-known environmental pollutant associated with neurological and developmental deficits in animals and humans. However, epidemiological data showed that people living in the Amazon region although exposed to MeHg do not present these effects probably due to the protective effect of certain foods. We hypothesized here if guarana, a highly caffeinated fruit and consumed on a daily basis by Amazon people, could have some protective effect against MeHg toxicity using two complementary approaches. To assess locomotor impairment and sleep disruption, we used fruit fly (Drosophila melanogaster) model, and to evaluate neuroinflammation, we used human SH-SY5Y neural cells by measuring inflammatory cytokines levels. Results showed that guarana had a protective effect on the locomotor activity of male fruit flies reducing the excessive sleepiness caused by MeHg and increasing daily activity. Also, guarana increased the viability of flies and attenuated neural cells mortality. In addition, guarana reduced all pro-inflammatory cytokines levels increased by MeHg, along with caspase-1, caspase -3, caspase-8, and 8-dOHG levels, whereas increased the anti-inflammatory (IL-10) cytokine levels, which was decreased by MeHg. Our study provides new insights on the protective effects of guarana on the viability, locomotor activity, sleep, and activity patterns in vivo and the in vitro neuronal anti-inflammatory effect against MeHg toxicity.

Non-Essential Trace Elements Dietary Exposure in French Polynesia: Intake Assessment, Nail Bio Monitoring and Thyroid Cancer Risk

Background:

In French Polynesia, thyroid cancer mortality and incidence is reported to be the highest in the world. Excessive levels of non-essential trace elements (nETE) in the body are associated with several types of cancer.

Objective:

The present study aims to provide quantitative information on food contamination by mercury (Hg), lead (Pb), arsenic (As) and cadmium (Cd) in French Polynesia and its potential correlation with measurements performed in fingernails of Polynesians, and then to investigate the potential association between these nETE and different thyroid cancer risks.

Methods:

The study population included 229 interviewed cases and 373 interviewed controls We performed a descriptive analysis of Polynesian food and examined the association between thyroid cancer risk and daily intake levels of nETE and with fingernail nETE levels.

Results:

Hg contamination was mainly present in sea products, Pb contamination was present in almost all samples, Cd was detectable in starchy food and As was detectable in all sea products. No patient exceeded dietary contamination WHO limits for Pb, 2 participants exceeded it for Hg and 3 individuals (0.5%) for cadmium. In fingernail clippings, the most detectable pollutant was Pb (553 participants), then Hg (543 participants) then Cd (only in 130 participants). Thyroid cancer risk was increased more than 4 times by Pb daily intake in patients with a history of cancer in first-degree relatives than in ones without (p for interaction =0.01), and 2 times more in women with more than 3 pregnancies than in those with none or less (p for interaction =0.005); it was also increased following As intake by more than 30% in patients with a history of cancer in first-degree relatives than in ones without (p for interaction =0.05).

Conclusion:

Locally produced foods are not a source of nETE exposure in French Polynesia. Dieatry nETE exposure and fingernail nETE concentration are not associated to differentiated thyroid cancer risk. No correlation found between nETE dietary exposure and fingernail nETE concentration.

Oxidative stress in opium users after using lead-adulterated opium: The role of genetic polymorphism

Use of lead-adulterated opium has become one of the major sources of lead poisoning in Iran. This study was designed to assess clinical effects and oxidative stress and its association with GSTM1, GSTT1, NQO1, and ALAD genes polymorphisms and blood lead level (BLL) in lead-adulterated opium users. The oxidative stress status in 192 opium users with lead poisoning symptoms measured and compared with 102 healthy individuals. Gluthatione S-transferase (GST)-M1 and -T1 genes deletion, NQO1 rs1800566, and δ-aminolevulinic acid dehydratase (ALAD) rs1800435 polymorphisms were determined using PCR and PCR-RFLP. The relation between the polymorphisms, BLL, and oxidative stress parameters were analysed using multivariate linear regressions. The common symptoms of lead toxicity were gastrointestinal and neurologic complications. Oxidative stress was significantly higher in opium addicts and lipid peroxidation significantly correlated with BLL. There was significant association between ALAD rs1800435 and BLL, and the BLL was significantly lower in the patients with ALAD 1-2 genotype. Use of lead-adulterated opium causes high frequency of lead toxicity symptoms, hematological and biochemical abnormalities, and oxidative stress which are associated with BLL. Route of opioid use and the polymorphism of rs1800435 in ALAD gene are the major determinants of BLL in lead-adulterated opium users.

Genetic Susceptibility to Neurodegeneration in Amazon: Apolipoprotein E Genotyping in Vulnerable Populations Exposed to Mercury

Human exposure to mercury is a serious problem of public health in Amazon. As in other vulnerable populations throughout the world, Amazonian riverine populations are chronically exposed to this metal and some symptoms of mercury intoxication were already detected in these populations. However, studies on the genetic susceptibility to mercury toxicity in the Amazon are scarce, and they tested a limited number of individuals. In this context, apolipoprotein E gene (APOE) is a key element with a well-established association among their alleles and the neurodegenerative consequences of mercury intoxication. However, no studies have addressed APOE genotyping in Amazonian exposed populations. Additionally, epidemiological studies with APOE genotyping in Amazon have been restricted to indigenous populations. Therefore, this work analyzed for the first time the genotypic and allelic profiles of APOE in Amazonian riverine populations chronically exposed to mercury. Eight hundred and twenty three individuals were enrolled in our study donating blood (794) and/or hair (757). APOE genotyping was analyzed by real-time PCR. Total mercury and mercury species were quantified by ICP-MS and GC-pyro-AFS, respectively. Genomic ancestry markers were evaluated by multiplex-PCR reaction, separated by capillary electrophoresis on the ABI 3130 Genetic Analyzer instrument and analyzed on GeneMapper ID v3.2. The 𝜀3 and 𝜀3/𝜀3 were the most frequent allele and genotype, respectively, followed by 𝜀4 allele and 𝜀3/𝜀4 genotype. Only 𝜀2/𝜀2 genotype was not found, suggesting that the absence of this genotype is a generalized phenomenon in Amazon. Also, our data supported an association between the presence of APOE4 and the Amerindian origin in these populations. Fifty-nine individuals were identified at maximum risk with levels of mercury above 10 μg/g and the presence of APOE4. Interestingly, among individuals with high mercury content, APOE4-carriers had high mercury levels than APOE2-carriers, pointing to a different heavy metal accumulation according to the APOE allele. These data suggest that APOE4, in addition to a possible pharmacodynamic effect, may influence pharmacokinetically the mercury exposure causing its higher accumulation and leading to worse deleterious consequences. Our results may aid in the development of prevention strategies and health policy decision-making regarding these at-risk vulnerable populations.

Modulators of mercury risk to wildlife and humans in the context of rapid global change

Environmental mercury (Hg) contamination is an urgent global health threat. The complexity of Hg in the environment can hinder accurate determination of ecological and human health risks, particularly within the context of the rapid global changes that are altering many ecological processes, socioeconomic patterns, and other factors like infectious disease incidence, which can affect Hg exposures and health outcomes. However, the success of global Hg-reduction efforts depends on accurate assessments of their effectiveness in reducing health risks. In this paper, we examine the role that key extrinsic and intrinsic drivers play on several aspects of Hg risk to humans and organisms in the environment. We do so within three key domains of ecological and human health risk. First, we examine how extrinsic global change drivers influence pathways of Hg bioaccumulation and biomagnification through food webs. Next, we describe how extrinsic socioeconomic drivers at a global scale, and intrinsic individual-level drivers, influence human Hg exposure. Finally, we address how the adverse health effects of Hg in humans and wildlife are modulated by a range of extrinsic and intrinsic drivers within the context of rapid global change. Incorporating components of these three domains into research and monitoring will facilitate a more holistic understanding of how ecological and societal drivers interact to influence Hg health risks.

Genetic Aspects of Susceptibility to Mercury Toxicity: An Overview

Human exposure to mercury is still a major public health concern. In this context, children have a higher susceptibility to adverse neurological mercury effects, compared to adults with similar exposures. Moreover, there exists a marked variability of personal response to detrimental mercury action, in particular among population groups with significant mercury exposure. New scientific evidence on genetic backgrounds has raised the issue of whether candidate susceptibility genes can make certain individuals more or less vulnerable to mercury toxicity. In this review, the aim is to evaluate a new genetic dimension and its involvement in mercury risk assessment, focusing on the important role played by relevant polymorphisms, located in attractive gene targets for mercury toxicity. Existing original articles on epidemiologic research which report a direct link between the genetic basis of personal vulnerability and different mercury repercussions on human health will be reviewed. Based on this evidence, a careful evaluation of the significant markers of susceptibility will be suggested, in order to obtain a powerful positive “feedback” to improve the quality of life. Large consortia of studies with clear phenotypic assessments will help clarify the “window of susceptibility” in the human health risks due to mercury exposure.

Current progress on understanding the impact of mercury on human health

Mercury pollution and its impacts on human health is of global concern. The authors of this paper were members of the Plenary Panel on Human Health in the 12th International Conference on Mercury as a Global Pollutant held in Korea in June 2015. The Panel was asked by the conference organizers to address two questions: what is the current understanding of the impacts of mercury exposure on human health and what information is needed to evaluate the effectiveness of the Minamata Convention in lowering exposure and preventing adverse effects. The authors conducted a critical review of the literature published since January 2012 and discussed the current state-of-knowledge in the following areas: environmental exposure and/or risk assessment; kinetics and biomonitoring; effects on children development; effects on adult general populations; effects on artisanal and small-scale gold miners (ASGM); effects on dental workers; risk of ethylmercury in thimerosal-containing vaccines; interactions with nutrients; genetic determinants and; risk communication and management. Knowledge gaps in each area were identified and recommendations for future research were made. The Panel concluded that more knowledge synthesis efforts are needed to translate the research results into management tools for health professionals and policy makers.

Toxicology of metals and metalloids: Promising issues for future studies in environmental health and toxicology

The function and behavior of chemical elements in ecosystems and in human health probably comprise one of the most studied issues and a theme of great interest and fascination in science. Hot topics are emerging on an annual basis in this field. Bearing this in mind, some promising themes to explore in the field of metals and metalloids in the environment and in toxicology are highlighted and briefly discussed herein.

GPX1 Pro198Leu polymorphism and GSTM1 deletion do not affect selenium and mercury status in mildly exposed Amazonian women in an urban population

Mercury is potent toxicant element, but its toxicity can be reduced by forming a complex with selenium for safe excretion. Considering the impact of mercury exposure in the Amazon region and the possible interaction between these two elements, we aimed to assess the effects of Pro198Leu polymorphism to GPX1 and GSTM1 deletion, on mercury levels in a population from Porto Velho, an urban locality in the Brazilian Amazon region. Two hundred women from the capital city of Rondônia state were recruited for this study with 149 deemed suitable to participate. We assessed dietary intake using 24-hour recall. Selenium levels in plasma and erythrocytes were measured using hydride generation quartz tube atomic absorption spectroscopy and total hair mercury using cold vapor atomic absorption spectrometry. Oxidative stress parameters (GPx activity, oxygen radical absorbency capacity [ORAC] and malondialdehyde [MDA]) were also analyzed. All participants were genotyped for Pro198Leu polymorphism and GSTM1 deletion. We observed that this population presented high prevalence of selenium deficiency, and also low levels of mercury, likely due to food habits that did not include selenium-rich food sources or significant consumption of fish (mercury biomagnifiers) regularly. Univariate statistical analysis showed that Pro198Leu and GSTM1 genotypes did not affect selenium and mercury levels in this population. Pro198Leu polymorphism and GSTM1 deletion had no effect on mercury levels in mildly exposed people, suggesting these genetic variants impact mercury levels only in highly exposed populations.

Metal and Microelement Biomarkers of Neurodegeneration in Early Life Permethrin-Treated Rats

Hair is a non-invasive biological material useful in the biomonitoring of trace elements because it is a vehicle for substance excretion from the body, and it permits evaluating long-term metal exposure. Here, hair from an animal model of neurodegeneration, induced by early life permethrin treatment from the sixth to 21th day of life, has been analyzed with the aim to assess if metal and microelement content could be used as biomarkers. A hair trace element assay was performed by the ICP-MS technique in six- and 12-month-old rats. A significant increase of As, Mg, S and Zn was measured in the permethrin-treated group at 12 months compared to six months, while Si and Cu/Zn were decreased. K, Cu/Zn and S were increased in the treated group compared to age-matched controls at six and 12 months, respectively. Cr significantly decreased in the treated group at 12 months. PCA analysis showed both a best difference between treated and age-matched control groups at six months. The present findings support the evidence that the Cu/Zn ratio and K, measured at six months, are the best biomarkers for neurodegeneration. This study supports the use of hair analysis to identify biomarkers of neurodegeneration induced by early life permethrin pesticide exposure.

Assessing determinants of maternal blood concentrations for persistent organic pollutants and metals in the eastern and western Canadian Arctic

Aboriginal peoples in the Canadian Arctic are exposed to persistent organic pollutants (POPs) and metals mainly through their consumption of a traditional diet of wildlife items. Recent studies indicate that many human chemical levels have decreased in the north, likely due to a combination of reduced global chemical emissions, dietary shifts, and risk mitigation efforts by local health authorities. Body burdens for chemicals in mothers can be further offset by breastfeeding, parity, and other maternal characteristics. We have assessed the impact of several dietary and maternal covariates following a decade of awareness of the contaminant issue in northern Canada, by performing multiple stepwise linear regression analyses from blood concentrations and demographic variables for 176 mothers recruited from Nunavut and the Northwest Territories during the period 2005-2007. A significant aboriginal group effect was observed for the modeled chemicals, except for lead and cadmium, after adjusting for covariates. Further, blood concentrations for POPs and metals were significantly associated with at least one covariate of older age, fewer months spent breastfeeding, more frequent eating of traditional foods, or smoking during pregnancy. Cadmium had the highest explained variance (72.5%) from just two significant covariates (current smoking status and parity). Although Inuit participants from the Northwest Territories consumed more traditional foods in general, Inuit participants from coastal communities in Nunavut continued to demonstrate higher adjusted blood concentrations for POPs and metals examined here. While this is due in part to a higher prevalence of marine mammals in the eastern Arctic diet, it is possible that other aboriginal group effects unrelated to diet may also contribute to elevated chemical body burdens in Canadian Arctic populations.