The influence of changes in lifestyle and mercury exposure in riverine populations of the Madeira River (Amazon Basin) near a hydroelectric project

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Levels of Total Mercury and Health Risk Assessment of Consuming Freshwater Stingrays (Chondrichthyes: Potamotrygoninae) of the Brazilian Amazon

Mercury is an element with potential risk to fish and those who consume it. Thus, this study aimed to determine the levels of total mercury (THg), carry out a health risk assessment related to the consumption of the freshwater stingrays Potamotrygon motoro, and determine the physical and chemical properties of the water where stingrays occur. Stingrays of the species P. motoro were obtained from the Amazon River, and samples of the animals' musculature were collected to determine THg levels. Risk assessment was conducted using pre-established formulas of estimated monthly intake (EMI), maximum monthly intake rate (IRmm), and hazard quotient (HQ). Three population scenarios were evaluated, considering both sexes and differences between rural and urban areas. There was no relationship between weight and THg concentration nor between total length and THg concentration. Higher EMI values were observed in rural children; for the IRmm, male children had the lowest consumption levels. For the hazard quotient, there was a similarity between the three age groups when comparing the male and female sexes. In addition, the representatives of the rural area always had lower values than the urban area. Freshwater stingrays, like other elasmobranchs, can be crucial animal species because they act as sentinels in studies that assess harmful chemicals like mercury.

Large hydropower projects increase stress despite compensation efforts: Evidence from the Brazilian Amazon

Large hydropower projects continue to be built in developing nations, despite their known negative impacts. Large-scale energy projects strain local infrastructure and reduce access to infrastructure for households that live near them. Here we investigate the link between large-scale hydropower projects and stress. Our results suggest that these projects create stress through two mechanisms: strains on community resources and through the process of displacement. We also ask how compensation and resettlement programs condition these relationships. Using data from the Madeira river basin in the Brazilian Amazon, we find that hydropower projects increase stress by reducing access to energy, water, sanitation and land. Compensation provided was not sufficient to moderate this effect.

Sociobehavioral, Biological, and Health Characteristics of Riverside People in the Xingu Region, Pará, Brazil

This study aimed to evaluate the sociodemographic, behavioral, and biological profile and its relationship with the emergence of chronic non-communicable diseases in riverside populations in the Xingu region, Pará, Brazil. Characteristics related to health indicators and which risk factors are considered most important were analyzed. This is a cross-sectional, exploratory, and descriptive study. The sample consisted of riverside people of over 18 years of both sexes. The sample size (n = 86) was calculated with a confidence level of 95% and a sample error of 5%. The K-means clustering algorithm was adopted through an unsupervised method to divide the groups, and the values were expressed as a median. For continuous and categorical data, the Mann-Whitney and chi-square tests were used, respectively, and the significance level was set at p < 5%. The multi-layer perceptron algorithm was applied to classify the degree of importance of each variable. Based on this information, the sample was divided into two groups: the group with low or no education, with bad habits and worse health conditions, and the group with opposite characteristics. The risk factors considered for cardiovascular diseases and diabetes in the groups were low education (p < 0.001), sedentary lifestyle (p < 0.01), smoking, alcoholism, body mass index (p < 0.05), and waist-hip ratio, with values above the expected being observed in both groups. The factors considered important so as to be considered to have good health condition or not were the educational and social conditions of these communities, and one part of the riverside population was considered healthier than the other.

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.

Metal bioaccumulation in fish from the Araguari River (Amazon biome) and human health risks from fish consumption

Recently, high concentrations of metals have been found in the waters from sampling sites located in the Araguari River lower section. These metals can be bioaccumulated by fish, but also biomagnified, representing a potential risk through human consumption. Here, we aimed to (1) determine the metal concentrations in muscle samples from fish; (2) evaluate bioaccumulation of metals in muscle tissue of fish species with different feeding behaviors; and (3) investigate the risks of single metals, as well as mixture of metals, to human fish consumption. Eleven fish species were sampled (3 carnivorous, 5 omnivorous, and 3 detritivorous). In four fish species, Cd and Pb concentrations exceeded the Brazilian maximum limits (MLs) for human consumption. Individually, Pb and Cd concentrations in the muscle of these fish indicate risks to human health. When considering the mixture of metals, the consumption of all fish species represents risks. The highest risks implicate detritivorous species. For all fish species evaluated, the estimated daily intake (EDI) of Hg shows values above its reference dose (RfD). Our results suggest the need to establish an environmental monitoring program that aims to preserve environmental quality, biodiversity, and human health. It is also necessary to develop actions that aim to educate Amazonian populations on safe fish preparation and consumption.

Mercury in blood, hair, and feces from subsistence fish-eating riverines of the Madeira River Basin (Western Amazon)

BACKGROUND

The Madeira River (Amazon Basin) has been impacted by activities related to artisanal and small-scale gold mining (ASGM), deforestation and burning (for timber, agriculture, and hydroelectric dam projects). All these activities contribute to environmental mercury (Hg) release and cycling into the Amazon ecosystem and thus to changing lifestyles.

METHOD

We assessed exposure to total and MeHg in two small riverine communities of the Madeira River (Amazon): Lago Puruzinho (LP, n = 26 families) and São Sebastião do Tapurú (SST, n = 31 families). Samples of human hair (n = 137), blood (n = 39), and feces (n = 41) were collected from adults and children (0-15 years of age).

RESULTS

In women of childbearing age from LP village, the mean blood total-Hg (THg) (45.54 ± 24.76 μg.L^-1) and MeHg (10.79 ± 4.36 μg.L^-1) concentrations were significantly (p = 0.0024; p < 0.0001, respectively) higher than in women from SST village (THg: 25.32 ± 16.75 μg.L^-1; MeHg: 2.32 ± 1.56 μg.L^-1) village; the trend in hair-Hg persisted but was statistically significant (p < 0.0145) only for THg (LP, 11.34 ± 5.03 μg. g^-1; SST, 7.97 ± 3.51 μg. g^-1). In women, the median hair:blood ratio of total Hg was 269. In children, the mean hair THg concentrations were 6.07 ± 3.60 μg. g^-1 and 6.47 ± 4.16 μg. g^-1 in LP and SST; thus, not significantly different (p = 0.8006). There was a significant association (p < 0.001) between hair-Hg concentrations of mothers and their respective children. The excretion of Hg in feces of women (0.52 μg. g^-1 dw) was not significantly different from children (0.49 μg. g^-1 dw). The only statistically significant correlation between Hg in feces and in hair was found in children, (n = 16, r_s = 0.38, p = 0.005). Significant relationship was seen between the levels of THg in blood and hair of women from LP and SST. Based on hair-Hg concentrations, fish consumption rate ranged from 94.5 to 212.3 g.day^-1.

CONCLUSION

Women and children excrete THg in feces in comparable concentrations. However, the mean fish consumption rate and blood MeHg are higher in the most remote villagers. Mother`s hair-Hg concentration is a good predictor of children's hair-Hg.

Prevalence and factors associated with mercury exposure in riverside communities in the Brazilian Western Amazon

OBJECTIVE

to verify mercury exposure prevalence and identify its possible associated factors in two riverside communities in the Madeira River basin of the Western Brazilian Amazon.

METHOD

a cross-sectional study comprising 95 children and adolescents. Age cycle, school attendance, Bolsa Família, number of siblings, meals, fish consumption, height by age were measured. Binary logistic regression was used to verify relationships between mercury exposure and its possible associated factors.

RESULTS

the general prevalence of mercury exposure was 46.3%; children, 35.4%; and adolescents, 57.4%. Associated factors were fish consumption (aOR=1.84; 95%CI 1.56-2.16), age cycle (aOR=2.50; 95%CI 1.09-5.7), parasites (aOR=1.22; 95%CI 1.02-2.71), and short stature (aOR=1.32; 95%CI 1.05-2.02).

CONCLUSION

mercury exposure prevalence in riverside children and adolescents was considered worrying, with association with fish consumption, adolescence, parasites, and short stature.

Perceived Risk of Fish Consumption in a Low Fish Consumption Country

Among the numerous health benefits of fish consumption, perhaps the most recognized is the role of omega-3 fatty acids in the prevention of cardiovascular disease. Cardiovascular disease is prevalent in Hungary, which has the lowest fish consumption in Europe. Increasing fish consumption is the aim of most European countries and given the high incidence of cardiovascular disease in Hungary, it is of particular importance. A significant reduction of the VAT for fish in 1 January 2018 aimed to increase fish consumption in Hungary. However, despite reduced VAT, the price of fish in Hungary rose from 2017 to 2018. The aim of our research is to explore perceived risks that serve to exacerbate Hungarian consumers' low fish consumption, and to measure their effects to identify potential strategies to most effectively increase fish consumption. We applied partial least squares structural equation modeling (PLS-SEM) to analyze responses provided by 1042 survey participants (collected with face-to-face interviews, using quota sampling in 2014) to explore variables of fish consumption associated with perceived risk including psychological, physical, social, and functional risks. Our model is the first one that applies detailed perceived risk categories to measure those effects on low fish consumption. The results indicate that psychological risk associated with negative past experiences have both a direct, and through functional risk, an indirect significant negative effect on fish consumption. Conversely, neither social nor physical risk impede Hungarian fish consumption. We conclude that the seafood industry could benefit from targeted interventions that seek to reduce functional risk-perception of the person responsible for preparing fish in the household.

Toxic and essential trace element concentrations in fish species in the Lower Amazon, Brazil

The Lower Amazon region (Western Pará, northern Brazil) is greatly affected by mining exploitations (particularly artisanal gold mines) and other industrial and intensive agricultural activities with potentially strong impacts on aquatic ecosystems. Although such impacts include contamination with various toxic elements, to date only the effects of Hg have been considered. In this study, toxic and trace element concentrations were determined in the flesh of 351 fish specimens, including detritivores (Acarí, Pterygoplichthys pardalis), omnivores (Piranha, Pygocentrus nattereri; Pirarucu, Arapaima sp.) and carnivores (Caparari, Pseudoplatystoma fasciatum; Tucunaré, Cichla ocellaris), during the dry and wet seasons in 2015 and 2016. The range of concentrations of toxic element residues were 2-238 μg/kg fresh weight for As, 1-77 μg/kg for Cd, 4-1922 μg/kg for Hg and 1-30 μg/kg for Pb. Only the maximum concentrations of Hg established in the Brazilian legislation for fish destined for human consumption (0.5 mg/kg) were exceeded (in 16% of carnivorous species). The large between-species and seasonal differences observed for all these toxic elements are probably related to the seasonal behaviour and dietary habits of the different fish species. By contrast, essential trace element concentrations were low and not related to seasonal or dietary factors, and the observed differences may be at least partly related to the metabolism of each species. The associations between Hg and the essential trace elements Se, Fe, Co and Mn deserve special attention, as these trace elements may play a role in Hg cycling and methylation and merit further evaluation with the aim of reducing Hg toxicity in aquatic environments.

Mercury Exposure through Fish Consumption in Traditional Communities in the Brazilian Northern Amazon

Artisanal small-scale gold mining (ASGM) is the main source of anthropogenic mercury emissions and contamination in Latin America. In the Brazilian northern Amazon, ASGM has contaminated the environment and people over the past century. The main contamination route is through fish consumption, which endangers the food security and livelihoods of traditional communities. Our study aims to assess the potential toxicological health risks caused by the consumption of Hg-contaminated fish across five regions in Amapá State. We sampled 428 fish from 18 sites across inland and coastal aquatic systems. We measured the total mercury content in fish samples, and the results were applied to a mercury exposure risk assessment targeting three distinct groups (adults, women of childbearing age, and children). Mercury contamination was found to exceed the World Health Organization’s safe limit in 28.7% of all fish samples, with higher prevalence in inland zones. Moreover, the local preference for carnivorous fish species presents a serious health risk, particularly for communities near inland rivers in the region. This is the first study to provide clear recommendations for reducing the mercury exposure through fish consumption in Amapá State. It builds scientific evidence that helps decision-makers to implement effective policies for protecting the health of riverine communities.

Neuropsychological Effects of Mercury Exposure in Children and Adolescents of the Amazon Region, Brazil

BACKGROUND

Studies with children exposed to methylmercury (MeHg) through fish consumption in the Brazilian Amazon region report that the high levels of hair Hg are associated with significant decreases in intelligence, memory, attention, and visuospatial processing.

OBJECTIVE

To investigate the relationship between mercury exposure and neuropsychological functions in riverside communities of the Brazilian Amazon.

METHOD

263 participants aged 6 to 14 years old were assessed, from resettlement regions, near the Madeira river, Rondônia, Brazil. To assess the neuropsychological functions we used the following instruments: intelligence (WASI), working memory (Corsi Block-Tapping Task and Digit Span), verbal fluency (Word Generation - NEPSY II), inhibitory control (Inhibition Errors - NEPSY II), shifting (Trail Making Test) and manual motor dexterity (Grooved PegBoard Test). Socioeconomic status was obtained through household surveys. Total Hg levels were quantified hair samples (Total HgH) collected from the occipital region of the scalp and analyzed by Cold Vapor Atomic Absorption Spectrometry.

RESULTS

The group in the upper quartile of Total HgH levels presented lower scores on the tasks that assessed estimated IQ, visuospatial working memory, semantic knowledge and phonological verbal fluency, when compared to the group in the lower quartile level. A regression analysis controlled for age, sex, and maternal education showed that for each increase of 10 μg/g of Total HgH, there was a decrease around half standard deviation in Verbal IQ, estimated IQ scores, semantic knowledge, phonological verbal fluency and for verbal and visuospatial working memory.

CONCLUSIONS

High concentrations of Total Hg in hair were associated with a lower performance in neuropsychological functions tests. The results show that environmental exposure to Hg is associated to children and adolescents' lower neuropsychological performance in the riverine and resettled areas of the Brazilian Amazon region.

Dynamics of (total and methyl) mercury in sediment, fish, and crocodiles in an Amazonian Lake and risk assessment of fish consumption to the local population

Increasing concerns have been raised about the toxicity of mercury (Hg) to humans, especially for those that consume a great amount of fish. High Hg concentrations have previously been measured in Amazonian waterbodies, both resulting from natural and anthropogenic sources. However, few studies have been conducted so far in Amazonian lakes that are fished by local populations. In addition, few of those studies included methylmercury (MeHg), the most toxic and bioaccumulative Hg form, and evaluated the influence of physico-chemical conditions and season on Hg dynamics. In the present study, total Hg (THg) and MeHg concentrations were measured in bottom sediment as well as in two fish and two crocodile species of the Amazonian Cuniã Lake. Bottom sediment MeHg concentrations were higher in the dry season than in the wet season, which is related to differences in physico-chemical (pH and electrical conductivity) conditions. Diet appeared to be related with animal tissue MeHg concentrations, with the herbivorous fish having lower MeHg levels than the predatory fish and crocodiles. Based on the measured tissue concentrations and published data on local person weight and fish consumption, MeHg risk to Cuniã Lake populations was estimated. Although the MeHg fish tissue concentrations did not exceed national and international standards, a significant risk to the local population is anticipated due to their high fish consumption rates. Graphical abstract.

Oxidative Stress Levels Induced by Mercury Exposure in Amazon Juvenile Populations in Brazil

Oxidative stress can be induced by mercury (Hg) exposure, including through fish consumption (diet), leading to health risks. The objective of this study was to evaluate the association between oxidative stress biomarkers and dietary Hg exposure levels in riverine children and adolescents at Madeira River (RO/Brazil). Population from three riverine local communities presenting different fish consumption frequencies was sampled. Hg was determined in blood (ICP-MS) and glutathione (GSH); glutathione S-transferases (GST) and malondialdehyde (MDA) were determined in serum (spectrophotometry). Statistical analyses were performed using parametric and non-parametric tests. Multiple linear regression models and generalized additives models were also used to estimate the relationships between oxidative stress biomarkers and blood Hg. The juvenile riverine population from Cuniã RESEX presented the highest levels of oxidative stress and Hg levels in blood (GST = 27.2 (4.93) U/L, MDA = 1.69 (0.27) µmol/L, Hg = 20.6 (18.0) µg/L). This population also presented the highest frequency of fish consumption. The positive relation between Hg and GST and MDA, adjusted for individual characteristics, suggests an oxidative effect. This study shows the importance of oxidative stress biomarkers in the evaluation of dietary Hg exposure since initial and reversible metabolic changes were observed, enriching health risk assessments.

Influence of Maternal Fish Intake on the Anthropometric Indices of Children in the Western Amazon

We studied trends in fish intake among pregnant women living in the Madeira River Basin in Rondônia State, Brazil, to investigate the influence of maternal fish intake on anthropometric indices of children followed up to 5 years. Maternal fish intake was assessed using hair mercury concentrations of mothers and children at delivery and 6, 24, and 59 months. Data analysis was performed using a linear mixed-effect model. Mothers were predominantly young, had low incomes and limited schooling, and breastfed for >6 months. Only 1.9% of children had low birth weight. Anthropometric indices in approximately 80% of the study population showed Z-score values ranging from ≥-2 to ≤1. The influence of maternal fish intake on anthropometric indices, including height-to-age (H/A), weight-to-age (W/A), and weight-to-height (W/H) were not statistically significant after model adjustments. However, higher income and larger birth weight had a positive influence on H/A and W/A, whereas W/H gain was favored by higher maternal educational status and breastfeeding duration. Other variables (hemoglobin concentration and maternal age) had a positive significant influence on anthropometric indices. Maternal fish intake (or its attendant MeHg exposure) did not affect children growth. Nevertheless, it is advisable to avoid mercury-contaminated fish during pregnancy and childhood.

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.

Human Mercury Exposure in Yanomami Indigenous Villages from the Brazilian Amazon

In the Brazilian Amazon, where the majority of Yanomami villages are settled, mercury (Hg) exposure due to artisanal small-scale gold mining (ASGM) has been reported since the 1980s. This study assessed mercury exposure in the Yanomami reserve and whether the level of contamination was related to the ASGM geographical location. It was conducted using a cross-sectional study of 19 villages. Direct interviews were performed and hair samples were used as a bioindicator of Hg exposure. The Prevalence-Ratio (PR) was estimated as an indicator of association between ASGM geographical locations and human exposure to mercury. Mercury levels (239 hair samples) ranged between 0.4 and 22.1 μg·g-1 and presented substantial differences amongst the villages. In the Waikas-Aracaça region, where current ASGM was reported, we observed the highest Hg concentrations (median = 15.5 μg·g-1). Almost all participants presented with hair-Hg levels >6 μg·g-1 (prevalence = 92.3%). In the Paapiu region, we observed the lowest concentrations (median = 3.2 μg·g-1; prevalence = 6.7%). Our findings showed that the Waikas Ye'kuana and Waikas Aracaca villages presented with 4.4 (PR = 4.4; Confidence Interval (CI) 95% = 2.2⁻9.0) and 14.0 (PR = 14.0; CI 95% = 7.9⁻24.9) times higher prevalence of hair-Hg concentration, respectively, compared with Paapiu. Considering seasonal variation of Hg-exposure, the lowest concentrations were observed during the wet season (June⁻September) and the highest in the dry season (December⁻April). Our study suggests that there is an association between mercury exposure and ASGM geographical locations.

[A health survey in riverine communities in Amazonas State, Brazil]

Population-based health surveys are important tools for identifying disease determinants, especially in regions with widely dispersed populations and low health system coverage. The aim of this study was to describe the principal methodological aspects and to describe the socioeconomic, demographic, and health characteristics of the riverine populations of Coari, Amazonas State, Brazil. This was a population-based cross-sectional study in river-dwelling communities in the rural area of Coari, from April to July 2015. The probabilistic cluster sample consisted of 492 individuals. The results showed that the majority of the river-dwellers were females (53%), had up to 9 years of schooling (68.5%), and earned a monthly family income equivalent to one-third the minimum wage. The health problems reported in the previous 30 days featured conditions involving pain (45.2%). The main healthcare resources were allopathic medicines (70.3%), exceeding herbal remedies (44.3%). The river-dwellers travel an average of 60.4km and take some 4.2 hours to reach the urban area of Coari. The riverine population generally presents low economic status and limited access to the urban area. Health problems are mostly solved with allopathic medicines. Geographic characteristics, as barriers to access to health services and to improvements in living conditions for the riverine population, can limit the collection of epidemiological data on these populations.

A Systematic Review of Children's Environmental Health in Brazil

In the region of the Americas, approximately 100,000 children under the age of 5 years die each year due to environmental hazards. Brazil, due to its large size and wide range of environmental challenges, presents numerous hazards to children's health. The aim of this study was to systematically review the scientific literature that describes children's exposures to environmental pollutants in Brazil and their effects on Brazilian children's health. A systematic review of the scientific literature was performed without language restrictions and time of publication (years). The literature search was conducted in the following key resources: PubMed (MEDLINE), Scopus and Web of Science with the MeSH Terms: Environmental exposure AND Brazil (filters: Human, Child [birth to 18 years] and Affiliation Author). The Virtual Health Library was also employed to access the databases Scielo and Lilacs. The search strategy was [DeCS Terms]: Child OR adolescent AND Environmental exposure AND Brazil. Health effects in children associated with exposure to environmental pollutants in Brazil were reported in 74 studies, during the period between 1995 and 2015. The most frequently cited effect was hospital admission for respiratory causes including wheezing, asthma, and pneumonia among children living in areas with high concentrations of air pollutants. A broad spectrum of other health effects possibly linked to pollutants also was found such as prematurity, low birth weight, congenital abnormality (cryptorchidism, hypospadia, micropenis), poor performance in tests of psychomotor and mental development, and behavioral problems. Exposure to pesticides in utero and postnatally was associated with a high risk for leukemia in children <2 years old. These results show that there is a need in Brazil for stricter monitoring of pollutant emissions and for health surveillance programs especially among vulnerable populations such as pregnant women and young children.

Child Nutritional Status in the Changing Socioeconomic Region of the Northern Amazon, Brazil

The living conditions (i.e., socioeconomic, healthcare-related, nutritional, and environmental) to which children are exposed may influence their ability to reach their optimal growth potential. This review focuses on the relationship between the nutritional status of children under five years of age and social and environmental factors in Northern Brazil. Children living in this region have limited access to healthcare and face precarious socioeconomic and environmental conditions. This analysis was based on data from national health surveys, the consolidated food, nutrition surveillance system (SISVAN), and indicators of the DPSEEA (driving force, pressure, state, exposures, health effects, and actions) framework. The northern region has the worst living conditions in the country, and children under five years of age have significant height-for-age, weight-for-age, and weight-for-height deficits. Concomitantly, the prevalence of children who are overweight has increased significantly, although it remains lower than that in more developed Brazilian regions. Insufficient and/or inadequate dietary practices and early exposure to unfavorable living conditions are risk factors for nutritional deviations. Further advances in public health policies that consider regional characteristics, particularly in the north, where progress has been slower, are needed.

Selenium Levels in the Whole Blood of Children and Teenagers from Two Riparian Communities at the Madeira River Basin in the Western Brazilian Amazon

Selenium (Se) is an essential micronutrient that exerts multiple functions in the organism, and both its deficiency and excess can cause health impairments. Thus, it is important to monitor its levels in the population, especially in vulnerable groups, such as children from the Brazilian Amazon region, where there is a lack of information in this regard. The aim of this research was to study Se levels in the whole blood of children and teenagers (5-16 years old) from two riparian communities at the Madeira River (Cuniã RESEX and Belmont). Se level variations related to the communities' location, seasonality, diet, and body mass index (BMI) were assessed. Blood samples were collected in both communities for Se determinations, using ICP-MS and hemogram analyses, during May and September of 2011. Food frequency questionnaires were applied to assess consumption rates of specific food items. Non-parametric tests and linear multiple regressions were applied in the data analyses. Median Se levels were significantly higher during May (Cuniã RESEX 149 μg L^-1; Belmont 85 μg L^-1) compared to September (Cuniã RESEX 79 μg L^-1; Belmont 53 μg L^-1). No significant differences were found between the communities regarding BMI measurements and anemia prevalence. However, Se blood levels were significantly higher at the Cuniã RESEX compared to Belmont. In addition, the former showed higher fish and Brazil nut intakes, which may be the main Se sources for this community. These results contribute to a better understanding of Se reference levels for children and teenagers of Western Amazon riparian communities.

Mercury levels and human health in the Amazon Basin

CONTEXT

Environmental mercury in the Amazon mostly originates from geochemical sources with some from artisanal gold mining (AGM). Geochemical-originated methylmercury (MeHg) reaches the aquatic food chain, ending up in fish. Inorganic Hg used in AGM is responsible for localised environmental contamination and occupational exposure of adults. In addition to this, iatrogenic ethylmercury (EtHg) derived from Thimerosal-containing vaccines (TCVs) exposes immunised infants.

OBJECTIVE

To understand Hg exposure in the Amazon in relation to environmental fish-MeHg exposure, occupational AGM activities and low-doses of TCV-EtHg.

METHODS

Medline and Thomson-Reuter Web of Science were searched to retrieve and select papers addressing Hg exposure and human health.

RESULTS AND CONCLUSION

Environmental-Hg studies addressed health effects associated with birth weight, infant linear growth and neurodevelopment, while, in adults, environmental and occupational studies addressed immune and neurological issues. No widespread clinical toxicity was reported due to fish-MeHg. However, mixed results associated with Hg exposure can be found. Reducing children's exposure to EtHg is possible using Thimerosal-free vaccines, but it is difficult to interfere with fish consumption without consequences to riverine subsistence populations. Policies to diminish Hg exposure should focus on controlling and/or curbing widespread use of Hg (in gold amalgamation) and promotion of Thimerosal-free vaccines for pregnant women and young children.

Impact of organic mercury exposure and home delivery on neurodevelopment of Amazonian children

In the transitioning Amazon, we addressed birth environment (home vs hospital) and associated perinatal organic-Hg exposures: methylmercury (MeHg) from maternal fish consumption and ethylmercury (EtHg) from pediatric Thimerosal-containing vaccines (TCVs) taken systematically during hospital delivery. We studied 365 children in relation to linear growth at 60 months and neurodevelopment (milestone achievements, Bayley Scale of Infant Development/BSID at 24 months, and Stanford-Binet intelligence tests at 60 months). Mothers delivered in hospitals vs those gave birth at home had significantly (p<0.0001) lower hair-Hg (HHg) concentrations (12.2 vs 23.9μg/g respectively) and shorter length of breastfeeding (8.5 vs 9.7 months respectively). Home-born children had significantly (p<0.0001) higher HHg (7.1μg/g) than hospital-born children (4.6μg/g). Hospital-born children also had significantly earlier (p<0.0001) hepatitis B vaccine than home-born children (1.5 vs 24.1days respectively) and higher (p<0.0001) exposures to total TCV-EtHg (75.8 vs 49.3μg respectively). Neither anthropometric indices nor neurodevelopment (except for fluid reasoning) were directly affected by birth environment. The percentage of hospital-born children with BSID (MDI or PDI) scores <80 was not significantly different from those born at home. In spite of the differences in HHg and EtHg levels between hospital-born and home-born children, no impact on neurodevelopment was observed.

Mercury in muscle and brain of catfish from the Madeira river, Amazon, Brazil

The central nervous system is a critical target for Hg toxicity in all living organisms. Total Hg (THg) was determined in brain and muscle samples of 165 specimens of eight species of catfish (Brachyplatystoma filamentosum; Brachyplatystoma platynemum; Brachyplatystoma rousseauxii; Brachyplatystoma vaillantii; Phractocephalus hemiliopterus; Pseudoplatystoma punctifer; Pseudoplatystoma tigrinum; Zungaro zungaro) from the Madeira River, Brazilian Amazon. Despite the narrow range of Fishbase trophic level (4.2-4.6) the median THg concentrations ranged from 0.39 to 1.99mg/kg and from 0.03 to 0.29mg/kg respectively in muscle and brain from the studied species. Overall, the median concentration for all samples analyzed was 0.93mg/kg and 0.16mg/kg respectively in muscle and brain; most samples (76%) showed muscle Hg concentrations >0.5mg/kg. There were statistically significant THg differences between sex (female>males). The correlation between THg concentrations in muscle and brain was statistically significant (r=0.9170; p<0.0001). In the studied specimens, fish total length was significantly correlated with muscle (r=0.3163; p=0.0001) and brain (r=0.3039; p=0.0003) THg; however, fish age was negatively and significantly correlated (r=-0.2991; p=0.0012) with THg in muscle but not with THg in brain (r=-0.0190; p=0.8492). Amazonian catfish accumulate high levels of Hg in muscle and brain; however, brain-THg concentrations can be predicted from muscle-THg. Muscle-Hg in catfish can be a tool to detect brain-Hg concentrations associated with environmental Hg.