Determinants of iron deficiency and anemia among Nunavimmiut: results from the Qanuilirpitaa? 2017 Nunavik Health Survey.

OBJECTIVE: To estimate the prevalence of iron deficiency (ID) and anemia and study their main distal and proximal protective and risk factors among Nunavimmiut 16 years and older in 2017. METHODS: In a cross-sectional participatory survey of 831 women and 436 men from the Qanuilirpitaa? 2017 Nunavik Inuit Health Survey, venous blood samples were collected to measure various indicators of iron status and anemia as well as biomarkers of nutritional and inflammatory status and contaminant exposures. Sociodemographic, food security status, anthropometric, lifestyle, dietary, and health data were collected using questionnaires, clinical sessions, and a medical chart review. ID and anemia diagnoses were based on serum ferritin (SF) and hemoglobin (Hb), respectively. Multiple regressions were used to assess correlates of anemia and iron status. RESULTS: Prevalence of ID was highest among women of childbearing age (16-49 years old, 33%) and anemia among adults aged 50 years and older (31%). These estimates are prone to biases due to the relatively low participation rate (37%). Serum vitamin D, omega-3 polyunsaturated fatty acid content of erythrocyte membranes, blood selenium, inflammation, higher socioeconomic status (SES), obesity, and alcohol consumption were all positively associated with SF, while Helicobacter pylori infection and a recent pregnancy were negatively associated with Hb among women of childbearing age. Among older adults, food insecurity was associated with lower SF. CONCLUSION: While data reported here provide some indication of an improvement since the previous survey conducted in 2004, additional efforts should be devoted to further increasing the SES and access to country foods and nutritious market foods in this population, the two main protective factors against ID and anemia identified in the present study.

RéSUMé: OBJECTIF: Estimer la prévalence de la carence en fer (CF) et de l'anémie et étudier leurs principaux facteurs de protection et de risque distaux et proximaux chez les Nunavimmiut de 16 ans et plus en 2017. MéTHODOLOGIE: Dans le cadre de l'enquête transversale participative Qanuilirpitaa? menée en 2017 auprès de 831 femmes et 436 hommes, des échantillons de sang furent prélevés pour mesurer divers indicateurs de la CF et de l'anémie ainsi que des biomarqueurs de l'état nutritionnel et inflammatoire et de l'exposition aux contaminants environnementaux. Des données sociodémographiques, anthropométriques, sur la sécurité alimentaire, sur le mode de vie, l'alimentation et la santé ont été recueillies à l'aide de questionnaires, de séances cliniques et d'un examen des dossiers médicaux. Les diagnostics de CF et d'anémie furent basés sur la ferritine sérique (SF) et l'hémoglobine (Hb), respectivement. Des régressions multiples ont été utilisées pour évaluer les déterminants de l'anémie et du statut en fer. RéSULTATS: La prévalence de la CF était la plus élevée chez les femmes en âge de procréer (16 à 49 ans, 33 %) et l'anémie chez les adultes âgés de 50 ans et plus (31 %). Ces estimés pourraient être biaisés puisque le taux de participation à l'enquête était relativement faible (37 %). Chez les femmes en âge de procréer, la vitamine D sérique, la teneur en acides gras polyinsaturés oméga-3 des membranes érythrocytaires, le sélénium sanguin, l'inflammation, un statut socio-économique plus élevé, l'obésité et la consommation d'alcool étaient tous associés positivement à la SF, tandis que l'infection à Helicobacter pylori et une grossesse récente étaient associées négativement à l'Hb. Chez les adultes plus âgés, l'insécurité alimentaire était associée à une diminution de la SF. CONCLUSION: Bien que les données de cette enquête suggèrent une amélioration depuis l'enquête précédente réalisée en 2004, des efforts additionnels sont requis pour améliorer le statut socioéconomique et l'accès aux aliments traditionnels et aux aliments de marché de qualité au Nunavik, les deux principaux facteurs protecteurs de la CF et de l'anémie identifiés dans la présente étude.

Exposure to benzene, toluene and polycyclic aromatic hydrocarbons in Nunavimmiut aged 16 years and over (Nunavik, Canada) - Qanuilirpitaa 2017 survey.

There are numerous volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) that Inuit may be exposed to from combustion, cooking, heating, vehicle exhaust, active and passive smoking and other local sources of contaminants such as oil spills or open-air burning in landfills. To better assess the levels of exposure to these non-persistent chemicals, we measured a suite of benzene, toluene (two VOCs) and PAHs metabolites in pooled urine samples from youth and adults aged 16 years old and over who participated in the Qanuilirpitaa? 2017 Inuit Health Survey (Q2017), a population health survey conducted in Nunavik. A cost-effective pooling strategy was established and 30 different pools from individual urine samples (n = 1266) were created by grouping individual urine samples by sex, age groups and regions. To assess smoking and exposure to second-hand smoke, cotinine levels were measured in individual urine samples. We found that benzene, toluene, all detected PAHs metabolites and cotinine levels were significantly higher in Q2017 compared to adults in the Canadian Health Measure Survey Cycle 4 (2014-2015) or the general U.S population (2015-2016). Moreover, mean levels of one benzene metabolite, S-phenylmercapturic acid, and several PAHs metabolites, 1-naphthol, 2-and 3-hydroxyfluorene, and 4- and 9-hydroxyphenanthrene, known to be associated with smoking habits, were higher in Q2017 compared to reference values (RV95) established for non-smokers in the general Canadian population. Furthermore, benzene and PAHs metabolites were all correlated with cotinine levels. Our results suggest that the high smoking prevalence in Nunavik is an important contributor to the elevated benzene and PAHs exposure. Other local sources may add to that exposure, although we were not able to account for their contribution. These data highlight the importance of regional and community efforts for reducing smoking and to encourage smoke-free homes in Nunavik, while continuing to investigate and reduce other possible local sources of exposure to benzene, toluene and PAHs.

Variation in biomarker levels of metals, persistent organic pollutants, and omega-3 fatty acids in association with genetic polymorphisms among Inuit in Nunavik, Canada.

BACKGROUND: Biomarker measures of contaminant exposure and nutrient status can help increase understanding of the risks and benefits associated with the consumption of traditional foods by Inuit. While gene-environment and gene-nutrient interactions may help explain variations in biomarker measures, the role of genetic polymorphisms is largely understudied especially for vulnerable sub-populations. OBJECTIVE: The aim of this study was to characterize the relationship between single nucleotide polymorphisms (SNPs) in key genes and blood concentrations of environmental chemicals and nutrients among Inuit. METHODS: Blood samples from 665 individuals who participated in the Qanuippitaa Survey (Nunavik, Canada) in 2004 were analyzed for toxicants and nutrients. DNA was extracted and 140 SNPs in classes relevant to the toxicokinetics and/or toxicodynamics of the target contaminants and nutrients, and/or are involved in cardiovascular health and lipid metabolism were genotyped using the Sequenom iPLEX Gold platform. RESULTS: Geometric means (µg/L) of mercury (Hg), cadmium (Cd), lead (Pb), DDE, PCB-153, and selenium (Se) were 11.1, 2.8, 39.9, 2.9, 1.1 and 301.2, respectively. Red blood cell membrane levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 5.1%/total fatty acid (TFA) and 1.3%/TFA respectively. Out of 106 SNPs which met our inclusion criteria, biomarker levels for Hg, Cd, Pb, DDE, PCB-153, DHA, and EPA differed (p < 0.05) by genotype for 20, 13, 12, 19, 21, 9 and 8 SNPs, respectively. Following Bonferroni correction (p < 0.0005), only 9 SNPs remained significant (rs2274976 in MTHFR, rs174602 in FADS2, rs7115739 and rs74771917 in FADS3, rs713041 in GPX4, rs2306283 and rs4149056 in SLCO1B1, rs1885301 in ABCC2/MRP2, and rs4244285 in CYP2C19; 5 associated with Hg, 2 with Pb, 2 with DDE, 4 with PCB-153, 1 with DHA). CONCLUSIONS: The findings suggest that polymorphisms in environmentally-responsive genes can influence biomarker levels of key toxicants and nutrients. While there are no immediate clinical or public health implications of these findings, we believe that such gene-environment and gene-nutrient studies provide a foundation that will inform and provide direction to future studies.

Anemia, iron status, and associated protective and risk factors among children and adolescents aged 3 to 19 years old from four First Nations communities in Quebec.

OBJECTIVES: Anemia and iron deficiency (ID) are frequent among Indigenous children of Canada, but few data are available in Quebec. The present study aimed to characterize anemia and ID prevalence and associated protective and risk factors among First Nations youth in Quebec. METHODS: The 2015 First Nations (JES!-YEH!) pilot study was conducted among children and adolescents (3 to 19 years; n = 198) from four First Nations communities in Quebec. Blood and urine samples and anthropometric measurements were collected. Hemoglobin (Hb), serum ferritin (SF), plasma hs-CRP, and urinary cotinine levels were measured. Factors associated with anemia and ID (including traditional and market food consumption) were assessed using an interview-administered food frequency questionnaire, based on which nutritional intakes were calculated. Structural equation models were used to test associations. RESULTS: The prevalence of anemia and ID was elevated (16.8% and 20.5% respectively). Traditional meat, fruit, and fruit juice (natural and powdered)-via their positive association with vitamin C intake-were the only food variables positively associated with SF (coefficient [95% CI] 0.017 [0.000, 0.114]; 0.090 [0.027, 0.161]; and 0.237 [0.060, 0.411]). Male sex was also associated with higher SF (0.295 [0.093, 0.502]). Inflammation status (hs-CRP > 5 mg/L) was inversely associated with Hb (- 0.015 [- 0.025, - 0.005]), whereas SF was positively associated with Hb (0.066 [0.040, 0.096]). Fruit and juice consumption was also positively associated with Hb, via vitamin C intake and SF (0.004 [0.001, 0.010]; 0.008 [0.003, 0.017]). CONCLUSIONS: Interventions fostering healthier food environments as well as higher consumption of traditional meats and foods naturally rich in vitamin C, which is known to enhance iron absorption, and fighting inflammation could contribute to decrease the high prevalence of anemia and ID in this young Indigenous population.

Genetic polymorphisms are associated with exposure biomarkers for metals and persistent organic pollutants among Inuit from the Inuvialuit Settlement Region, Canada.

BACKGROUND: Inuit are exposed to some of the highest levels of contaminants worldwide. Studies suggest that several genes that mediate the metabolism of these contaminants are polymorphic. We hypothesize that single nucleotide polymorphisms (SNPs) in such genes may underline differences in biomarker concentrations and/or modify exposure-biomarker associations. METHODS: Members from the Inuvialuit Settlement Region (Canada) were recruited. Blood concentrations of mercury (Hg), cadmium (Cd), lead (Pb), dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyl (PCB-153) were measured. SNPs from pathways such as glutathione, metallothionein, oxidative stress, and xenobiotic transport were genotyped in 281 participants, and data from 112 SNPs were included in the analyses. Surveys were administered to obtain information on demographics, and key sources of Hg (diet) and Cd (smoking) exposure. ANOVA and linear regressions were used for data analyses. RESULTS: Geometric mean concentrations of metals were 4.6µg/L for Hg, 1.3µg/L for Cd, and 32.2µg/L for Pb. Concentrations of organic pollutants were 2.0µg/L for DDE and 0.6µg/L for PCB-153. Biomarker levels for Hg, Cd, Pb, DDE, and PCB-153 differed (p<0.05) by genotype for 4, 3, 4, 3, and 3 SNPs, respectively. In multivariable analyses (for Pb, DDE, PCB-153) adjusting age, sex and body mass index (BMI), only 2 associations (one for Pb and one for DDE) remained significant. In multivariable analyses accounting for sources of Hg or Cd exposure, 24 SNPs (9 for Hg, 15 for Cd with 4 overlapping) had significant (p<0.05) main effects on biomarker levels and/or modified exposure-biomarker associations. CONCLUSION: The findings suggest that polymorphisms in key environmentally responsive genes can influence biomarker levels and/or modify exposure-biomarker associations for contaminants of concern to Arctic populations. Consideration of such gene-environment results may help improve the ability to conduct exposure (and ultimately risk) assessments of country foods and Inuit health.

Arctic berry extracts target the gut-liver axis to alleviate metabolic endotoxaemia, insulin resistance and hepatic steatosis in diet-induced obese mice.

AIMS/HYPOTHESIS: There is growing evidence that fruit polyphenols exert beneficial effects on the metabolic syndrome, but the underlying mechanisms remain poorly understood. In the present study, we aimed to analyse the effects of polyphenolic extracts from five types of Arctic berries in a model of diet-induced obesity. METHODS: Male C57BL/6 J mice were fed a high-fat/high-sucrose (HFHS) diet and orally treated with extracts of bog blueberry (BBE), cloudberry (CLE), crowberry (CRE), alpine bearberry (ABE), lingonberry (LGE) or vehicle (HFHS) for 8 weeks. An additional group of standard-chow-fed, vehicle-treated mice was included as a reference control for diet-induced obesity. OGTTs and insulin tolerance tests were conducted, and both plasma insulin and C-peptide were assessed throughout the OGTT. Quantitative PCR, western blot analysis and ELISAs were used to assess enterohepatic immunometabolic features. Faecal DNA was extracted and 16S rRNA gene-based analysis was used to profile the gut microbiota. RESULTS: Treatment with CLE, ABE and LGE, but not with BBE or CRE, prevented both fasting hyperinsulinaemia (mean ± SEM [pmol/l]: chow 67.2 ± 12.3, HFHS 153.9 ± 19.3, BBE 114.4 ± 14.3, CLE 82.5 ± 13.0, CRE 152.3 ± 24.4, ABE 90.6 ± 18.0, LGE 95.4 ± 10.5) and postprandial hyperinsulinaemia (mean ± SEM AUC [pmol/l × min]: chow 14.3 ± 1.4, HFHS 31.4 ± 3.1, BBE 27.2 ± 4.0, CLE 17.7 ± 2.2, CRE 32.6 ± 6.3, ABE 22.7 ± 18.0, LGE 23.9 ± 2.5). None of the berry extracts affected C-peptide levels or body weight gain. Levels of hepatic serine phosphorylated Akt were 1.6-, 1.5- and 1.2-fold higher with CLE, ABE and LGE treatment, respectively, and hepatic carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-1 tyrosine phosphorylation was 0.6-, 0.7- and 0.9-fold increased in these mice vs vehicle-treated, HFHS-fed mice. These changes were associated with reduced liver triacylglycerol deposition, lower circulating endotoxins, alleviated hepatic and intestinal inflammation, and major gut microbial alterations (e.g. bloom of Akkermansia muciniphila, Turicibacter and Oscillibacter) in CLE-, ABE- and LGE-treated mice. CONCLUSIONS/INTERPRETATION: Our findings reveal novel mechanisms by which polyphenolic extracts from ABE, LGE and especially CLE target the gut-liver axis to protect diet-induced obese mice against metabolic endotoxaemia, insulin resistance and hepatic steatosis, which importantly improves hepatic insulin clearance. These results support the potential benefits of these Arctic berries and their integration into health programmes to help attenuate obesity-related chronic inflammation and metabolic disorders. DATA AVAILABILITY: All raw sequences have been deposited in the public European Nucleotide Archive server under accession number PRJEB19783 ( https://www.ebi.ac.uk/ena/data/view/PRJEB19783 ).

Toxic risks and nutritional benefits of traditional diet on near visual contrast sensitivity and color vision in the Brazilian Amazon.

BACKGROUND: Visual functions are known to be sensitive to toxins such as mercury (Hg) and lead (Pb), while omega-3 fatty acids (FA) and selenium (Se) may be protective. In the Tapajós region of the Brazilian Amazon, all of these elements are present in the local diet. OBJECTIVE: Examine how near visual contrast sensitivity and acquired color vision loss vary with biomarkers of toxic exposures (Hg and Pb) and the nutrients Se and omega-3 FA in riverside communities of the Tapajós. METHODS: Complete visuo-ocular examinations were performed. Near visual contrast sensitivity and color vision were assessed in 228 participants (≥15 years) without diagnosed age-related cataracts or ocular pathologies and with near visual acuity refracted to at least 20/40. Biomarkers of Hg (hair), Pb (blood), Se (plasma), and the omega-3 FAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plasma phospholipids were measured. Multiple linear regressions were used to examine the relations between visual outcomes and biomarkers, taking into account age, sex, drinking and smoking. RESULTS: Reduced contrast sensitivity at all spatial frequencies was associated with hair Hg, while %EPA, and to a lesser extent %EPA+DHA, were associated with better visual function. The intermediate spatial frequency of contrast sensitivity (12 cycles/degree) was negatively related to blood Pb and positively associated with plasma Se. Acquired color vision loss increased with hair Hg and decreased with plasma Se and %EPA. CONCLUSIONS: These findings suggest that the local diet of riverside communities of the Amazon contain toxic substances that can have deleterious effects on vision as well as nutrients that are beneficial for visual function. Since remediation at the source is a long process, a better knowledge of the nutrient content and health effects of traditional foods would be useful to minimize harmful effects of Hg and Pb exposure.

Biomarkers of methylmercury exposure immunotoxicity among fish consumers in Amazonian Brazil.

BACKGROUND: Mercury (Hg) is a ubiquitous environmental contaminant with neurodevelopmental and immune system effects. An informative biomarker of Hg-induced immunotoxicity could aid studies on the potential contribution to immune-related health effects. OBJECTIVES: Our objectives were to test the hypothesis that methylmercury (MeHg) exposures affect levels of serum biomarkers and to examine interactions between Hg and selenium (Se) in terms of these responses. METHODS: This cross-sectional epidemiological study assessed adults living along the Tapajós River, a system long affected by MeHg. We measured antinuclear (ANA) and antinucleolar (ANoA) autoantibody levels and eight cytokines in serum samples (n = 232). Total Hg (including MeHg) and Se were measured in blood, plasma, hair, and urine. RESULTS: The median (range) total Hg concentrations were 14.1 µg/g (1.1-62.4), 53.5 µg/L (4.3-288.9), 8.8 µg/L (0.2-40), and 3.0 µg/L (0.2-16.1) for hair, blood, plasma, and urine, respectively. Elevated titers of ANA (but not ANoA) were positively associated with MeHg exposure (log-transformed, for blood and plasma), unadjusted [odds ratio (OR) = 2.6; 95% confidence interval (CI): 1.1, 6.2] and adjusted for sex and age (OR = 2.9; 95% CI: 1.1, 7.5). Proinflammatory [interleukin (IL)-6 and interferon (IFN)-γ], anti-inflammatory (IL-4), and IL-17 cytokine levels were increased with MeHg exposure; however, in the subset of the population with elevated ANA, proinflammatory IL-1ß, IL-6, IFN-γ, and tumor necrosis factor (TNF)-α and anti-inflammatory (IL-4) cytokine levels were decreased with MeHg exposure. Although Se status was associated with MeHg level (correlation coefficient = 0.86; 95% CI: 0.29, 1.43), Se status was not associated with any changes in ANA and did not modify associations between Hg and ANA titers. CONCLUSIONS: MeHg exposure was associated with an increased ANA and changes in serum cytokine profile. Moreover, alterations in serum cytokine profiles differed based on ANA response, suggesting a specific phenotype of MeHg susceptibility. Further research on the potential health implications of these observed immunological changes is warranted.

Selenium from dietary sources and motor functions in the Brazilian Amazon.

Selenium (Se) is a well-known anti-oxidant with a critical role in the proper functioning of nervous and muscle functions. Se deficiency has been associated with both cognitive and neuromotor impairment, while sensory and motor deficits have been attributed to excess Se. In the Lower Tapajós Region of the Brazilian Amazon, riverside populations present a wide range of Se levels. These fish-eating communities have among the highest mercury (Hg) exposures reported in the world today, and recently, lead (Pb) exposure has been identified. Some studies suggest that Se intake can be protective for Hg and/or Pb toxicity, however, data from animal and human studies are inconsistent. The objective of the present study was to examine the relations between biomarkers of Se and motor functions, taking into account co-variables and biomarkers of exposure to Hg and Pb. Participants (n=448), aged 15-87 y, were recruited from 12 communities along the Tapajós River. Se concentrations were measured in whole blood (B-Se), plasma (P-Se), hair (H-Se) and urine (U-Se) by ICP-MS. Whole blood Hg (B-Hg) and Pb (B-Pb) were also measured by ICP-MS. Interview-administered questionnaires served to collect information on socio-demographics and medical history. All participants underwent a complete visual examination and performed tests of motor functions (Branches Alternate Movement Task, Santa Ana Test, Dynamometer and Grooved Pegboard Test). B-Se varied from 103 to 1500 µg/L (median 228 µg/L), P-Se from 53.6 to 913 µg/L (median 135 µg/L), H-Se from 0.4 to 3.8 µg/g (median 0.7 µg/g) and U-Se from 2.3 to 1375 µg/g cr. (median 33.6 µg/g cr.). Median B-Hg and B-Pb levels were 42.5 µg/L and 113 µg/L respectively. In multivariable analysis, Se biomarkers (log-transformed) were positively related to better performance on all motor tests, taking into account socio-demographic co-variables and B-Hg and B-Pb levels. P-Se consistently showed stronger associations to motor performance compared to the other Se biomarkers. Regression estimates for Se biomarkers were considerably stronger when controlling for B-Hg. When stratifying at the median for B-Hg concentrations, P-Se consistently presented associations with the outcomes only at high B-Hg concentrations. This is the first human study to report beneficial effects of high Se status on motor functions. For this population with elevated Hg exposure, high dietary Se intake may be critical for brain and muscle functions. However, these findings are not necessarily applicable to populations with lower Hg exposure and/or Se status, which is the case for people who do not rely heavily on fish consumption, be they in Brazil, the United States or elsewhere. The associations were mostly observed with P-Se, suggesting that P-Se or plasma selenoproteins may be good biomarkers for these outcomes.

Quality of life and health perceptions among fish-eating communities of the brazilian Amazon: an ecosystem approach to well-being.

Mercury (Hg) contamination in the Brazilian Amazon constitutes a serious environmental and public health issue. This study is part of the CARUSO Project, which uses an ecosystem approach to human health to examine the sources, transmission, and effects of Hg in the Brazilian Amazon, with a view to developing preventive intervention strategy. To date, studies have focused on measures of Hg exposure through fish consumption in relation to health effects; little attention has been given to quality of life (QoL). The objective of this study was to examine the relations between QoL and health perceptions, Hg exposure, sociodemographics, living conditions, and lifestyle in communities along the Tapajós River. A total of 456 adults from 13 villages were interviewed and provided hair samples for Hg analysis. Results showed that perceptions of QoL and health are relatively positive, despite elevated Hg exposure. Logistic regression analyses showed that a positive perception of QoL was associated with the absence of chronic illnesses, not smoking, fruit consumption, residing on the banks of the Tapajós, and living in an in-migrants' community. The positive perception of health was associated with younger age, the absence of reported symptoms of chronic illnesses, and drinking alcoholic beverages. Cluster analysis revealed that the group that reported the highest QoL had a traditional lifestyle, involving daily fishing and high fish consumption. However, this traditional lifestyle is associated with elevated Hg levels and early reported symptoms potentially linked to Hg exposure. These findings underline the importance of understanding the factors underlying QoL to develop adequate strategies to reduce Hg exposure and promote well-being.

Biomarkers of selenium status in the Amazonian context: blood, urine and sequential hair segments.

Selenium (Se) is an essential element and deficit or excess of dietary Se is associated with health disorders. Relatively elevated Se levels have been reported in the Brazilian Amazon, where there are also important annual variations in the availability of different foods. The present study was conducted among six riparian communities of the Tapajós River to evaluate seasonal variations in blood and sequential hair cm Se concentrations, and to examine the relationships between Se in blood and hair, and blood and urine. Two cross-sectional studies were conducted, at the descending water (DWS, n=259) and the rising water (RWS, n=137) seasons, with repeated measures for a subgroup (n=112). Blood Se (B-Se), hair Se (H-Se) and urine Se (U-Se) were determined. Match-paired analyses were used for seasonal comparisons and the method of best fit was used to describe the relationships between biomarkers. B-Se levels presented a very large range (142-2447 microg/l) with no overall seasonal variation (median 284 and 292 microg/l, respectively). Sequential analysis of 13 cm hair strands showed significant variations over time: Se concentrations at the DWS were significantly lower compared with the rising water season (medians: 0.7 and 0.9 microg/g; ranges: 0.2-4.3 microg/g and 0.2-5.4 microg/g, respectively). At both seasons, the relationships between B-Se and H-Se were linear and highly significant (r(2)=67.9 and 63.6, respectively), while the relationship between B-Se and U-Se was best described by a sigmoid curve. Gender, age, education and smoking did not influence Se status or biomarker relationships. Variations in H-Se suggest that there may be seasonal availability of Se sources in local food. For populations presenting a large range and/or elevated Se exposure, sequential analyses of H-Se may provide a good reflection of variations in Se status.

A preliminary study of mercury exposure and blood pressure in the Brazilian Amazon.

BACKGROUND: Fish is considered protective for coronary heart disease (CHD), but mercury (Hg) intake from fish may counterbalance beneficial effects. Although neurotoxic effects of methylmercury (MeHg) are well established, cardiovascular effects are still debated. The objective of the present study was to evaluate blood pressure in relation to Hg exposure and fish consumption among a non-indigenous fish-eating population in the Brazilian Amazon. METHODS: The study was conducted among 251 persons from six communities along the Tapajós River, a major tributary of the Amazon. Data was obtained for socio-demographic information, fish consumption, height and weight to determine body mass index (BMI), systolic and diastolic blood pressure, and Hg concentration in hair samples. RESULTS: Results showed that overall, systolic and diastolic blood pressure, were relatively low (mean: 113.9 mmHg +/- 14.6 and 73.7 mmHg +/- 11.0). Blood pressure was significantly associated with hair total Hg (H-Hg), age, BMI and gender. No association was observed between fish consumption and blood pressure, although there were significant inter-community differences. Logistic regression analyses showed that the Odds Ratio (OR) for elevated systolic blood pressure (> or = 130 mmHg) with H-Hg > or = 10 microg/g was 2.91 [1.26-7.28], taking into account age, BMI, smoking, gender and community. CONCLUSION: The findings of this preliminary study add further support for Hg cardiovascular toxicity.

Elevated blood selenium levels in the Brazilian Amazon.

Contaminated fish poses a difficult challenge throughout the world, on the one hand, fish is a very nutritious food source, while on the other hand it accumulates many toxic substances, including mercury (Hg). As part of our efforts in the Brazilian Amazon to maximize nutritional input from fish consumption, a dietary mainstay, and minimize toxic risk, we have been studying the role of selenium (Se), an essential element, that may influence the distribution of Hg in the body and influence Hg neurotoxicity. Se, which is naturally present in the soil, is ingested through consumption of various foods, notably fish, mammals and certain plants. The objectives of the present study were: (i) evaluate whole blood Se (B-Se) and Hg (B-Hg); (ii) characterize B-Se variations with respect to socio-demographic and dietary variables; and (iii) examine the relation between B-Se and B-Hg. A total of 236 persons from six riparian communities of the Tapajós River Basin, a tributary of the Amazon, participated in this study. Whole blood Se and Hg were measured and interview administered questionnaires were used to obtain data on socio-demographic variable, smoking and drinking habits, and fish and fruit consumption. The results show that B-Se are in the upper normal range (median=284.3 microg/L, range=142.1-2029.3 microg/L). No individuals presented B-Se deficiency, but 9 participants from the same extended family had relatively high B-Se levels, potentially a threat to their health. B-Se varied between communities, was significantly higher among alcohol drinkers and farmers, but not associated with age, sex or tobacco consumption. A significant positive relation between B-Se and B-Hg was noted, independently of the overall fish consumption. B-Se increased with consumption of Peacock bass (Cichla sp.), a piscivorous fish species, and coconut pulp (Cocos nucifera L.). The B-Se intercommunity variations may reflect geographic differences in local soil Se levels as well as traditional land use practices in the different ecosystems of the Tapajós River Basin. In this population with relatively high exposure to Hg, Se may play an important role. Further studies should examine, in this region, the sources of Se, its transmission through the terrestrial and aquatic ecosystem and its role with respect to human health.