RESUMEN
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.
Asunto(s)
Visión de Colores , Sensibilidad de Contraste , Dieta , Contaminación de Alimentos , Alimentos Marinos , Adolescente , Adulto , Anciano , Biomarcadores/sangre , Brasil , Defectos de la Visión Cromática/etiología , Defectos de la Visión Cromática/prevención & control , Estudios Transversales , Dieta/efectos adversos , Ácidos Grasos Omega-3/sangre , Femenino , Cabello/química , Humanos , Plomo/efectos adversos , Plomo/sangre , Modelos Lineales , Masculino , Compuestos de Mercurio/efectos adversos , Compuestos de Mercurio/análisis , Persona de Mediana Edad , Análisis Multivariante , Factores de Riesgo , Alimentos Marinos/efectos adversos , Alimentos Marinos/análisis , Selenio/sangre , Pruebas de Visión , Adulto JovenRESUMEN
Selenium (Se) is an essential element and a well-known anti-oxidant. In the Lower Tapajós River region of the Brazilian Amazon, biomarkers of Se range from normal to very high. The local traditional diet includes important Se sources such as Brazil nuts, chicken, game meat and certain fish species. Some studies have reported alterations in keratin structure, gastrointestinal problems and paresthesia in populations with high Se intake. The objective of the present study was to evaluate cutaneous and garlic odor of the breath signs and sentinel symptoms of Se toxicity (selenosis) in relation to Se status in communities along the Tapajós River. Participants (N=448), aged 15-87 years, were recruited from 12 communities. Se concentrations were measured in blood (B-Se) and plasma (P-Se) by ICP-MS. A nurse performed an examination of the hair, nails, skin and breath for signs of Se toxicity. Interview-administered questionnaires were used to collect information on socio-demographics, medical history and possible symptoms of Se toxicity. In this population, the median levels of B-Se and P-Se were 228.4 µg/L (range 103.3-1500.2 µg/L) and 134.8 µg/L (range 53.6-913.2 µg/L) respectively. Although B-Se and P-Se surpassed concentrations considered toxic (B-Se: 1000 µg/L (U.S. EPA, 2002)), no dermal or breath signs or symptoms of Se toxicity were associated with the biomarkers of Se status. In the present study population, where Se intake is mostly from traditional diet, there is no evidence of selenosis. These findings support the need to re-assess Se toxicity considering factors such as the chemical form of Se exposure, route of exposure (inhaled versus ingested), co-exposures to toxic elements such as mercury. Considering the current food transition towards a western diet in the Amazon, further studies should address the possible association between high Se status and cardiometabolic health in this study population.
Asunto(s)
Dieta/estadística & datos numéricos , Micronutrientes/envenenamiento , Selenio/envenenamiento , Adulto , Bertholletia , Biomarcadores/análisis , Biomarcadores/metabolismo , Brasil , Pruebas Respiratorias , Estudios Transversales , Femenino , Cabello/química , Humanos , Masculino , Micronutrientes/metabolismo , Persona de Mediana Edad , Uñas/química , Selenio/análisis , Selenio/metabolismo , Piel/metabolismoRESUMEN
Since 1995, the Caruso Project used an Ecosystem Approach to Human Health to examine mercury (Hg) exposure in fish-eating communities in the Brazilian Amazon and develop interventions to maximise nutrition from traditional diet and minimise toxic risk. In 1995, 2000 and 2006, this study followed fish consumption, Hg levels, and visual and motor functions in 31 villagers. Questionnaires gathered information on socio-demographics and diet. Hair Hg (H-Hg) levels were measured. Visual acuity, colour vision, manual dexterity and grip strength were assessed. Data was analysed using general linear models of repeated measures. Total fish consumption, similar in 1995 and 2000, decreased in 2006. Carnivorous fish consumption initially decreased and then remained stable, whereas non-carnivorous fish consumption first increased and then decreased. H-Hg declined from 17.6 to 7.8 µg/g. Visual functions showed a significant decrease over time, with those with H-Hg ≥ 20 µg/g in 1995 showing greater loss. Motor functions showed initial improvement and then returned to the 1995 performance level. Decrease in Hg exposure is attributed to the intervention and socio-economic changes in the village. While there may be a certain reversibility of motor deficits, visual capacities may decrease progressively with respect to exposure prior to the intervention.
Asunto(s)
Contaminación de Alimentos/análisis , Intoxicación del Sistema Nervioso por Mercurio/complicaciones , Mercurio/análisis , Contaminación Química del Agua/análisis , Adolescente , Adulto , Animales , Brasil/epidemiología , Visión de Colores/efectos de los fármacos , Estudios Transversales , Conducta Alimentaria , Femenino , Peces/metabolismo , Cabello/química , Fuerza de la Mano , Humanos , Masculino , Intoxicación del Sistema Nervioso por Mercurio/epidemiología , Intoxicación del Sistema Nervioso por Mercurio/etiología , Persona de Mediana Edad , Ríos/química , Alimentos Marinos/análisis , Contaminación Química del Agua/efectos adversos , Adulto JovenRESUMEN
OBJECTIVE: To examine the associations between near and distant visual acuity and biomarkers of Hg, Pb, n-3 fatty acids and Se from the local diet of fish-eating communities of the Tapajós River in the Brazilian Amazon. DESIGN: Visuo-ocular health and biomarkers of Hg (hair, whole blood, plasma), Pb (whole blood), Se (whole blood and plasma) and n-3 fatty acids (plasma total phospholipids) were assessed in a cross-sectional study. SETTING: Lower Tapajós River Basin (State of Pará, Brazil), May to July 2006. SUBJECTS: Two hundred and forty-three adults (≥15 years) without diagnosed age-related cataracts or ocular pathologies. RESULTS: Near visual acuity was negatively associated with hair Hg and positively associated with %DHA, with a highly significant Log Hg × age interaction term. Stratifying for age showed that while young people presented good acuity, for those aged ≥40 years, clinical presbyopia was associated with hair Hg ≥ 15 µg/g (OR = 3·93, 95% CI 1·25, 14·18) and %DHA (OR = 0·37, 95% CI 0·11, 1·11). A similar age-related pattern was observed for distant visual acuity in relation to blood Pb, but the evidence was weaker. CONCLUSIONS: These findings suggest that Hg and Pb may affect visual acuity in older persons, while DHA appears to be protective for near visual acuity loss. In this population, with little access to eye care, diet may have an important influence on visuo-ocular ageing.
Asunto(s)
Dieta , Contaminación de Alimentos/análisis , Agudeza Visual , Contaminantes Químicos del Agua/análisis , Adolescente , Adulto , Anciano , Animales , Biomarcadores/sangre , Brasil , Estudios Transversales , Monitoreo del Ambiente/métodos , Ácidos Grasos Omega-3/sangre , Femenino , Peces , Cabello/química , Humanos , Plomo/sangre , Modelos Logísticos , Masculino , Mercurio/sangre , Persona de Mediana Edad , Análisis Multivariante , Medición de Riesgo , Ríos , Selenio/sangre , Factores Socioeconómicos , Adulto JovenRESUMEN
BACKGROUND: Age-related cataracts (ARCs) are an important cause of blindness in developing countries. Although antioxidants may be part of the body's defense to prevent ARC, environmental contaminants may contribute to cataractogenesis. In fish-eating populations of the lower Tapajós region, elevated exposure to mercury (Hg) has been reported, and blood levels of selenium (Se) range from normal to very high (> 1,000 microg/L). OBJECTIVES: We examined ARCs in relation to these elements among adults (> or = 40 years of age) from 12 riverside communities. METHODS: Participants (n = 211) provided blood samples and underwent an extensive ocular examination. Inductively coupled plasma mass spectrometry was used to assess Hg and Se in blood and plasma. RESULTS: One-third (n = 69; 32.7%) of the participants had ARC. Lower plasma Se (P-Se; < 25th percentile, 110 microg/L) and higher blood Hg (B-Hg; > or = 25th percentile, 25 microg/L) were associated with a higher prevalence odds ratio (POR) of ARC [adjusted POR (95% confidence interval), 2.69 (1.11-6.56) and 4.45 (1.43-13.83), respectively]. Among participants with high P-Se, we observed a positive but nonsignificant association with high B-Hg exposure, whereas among those with low B-Hg, we observed no association for P-Se. However, compared with the optimum situation (high P-Se, low B-Hg), the POR for those with low P-Se and high B-Hg was 16.4 (3.0-87.9). This finding suggests a synergistic effect. CONCLUSION: Our results suggest that persons in this population with elevated Hg, the cataractogenic effects of Hg may be offset by Se. Because of the relatively small sample size and possible confounding by other dietary nutrients, additional studies with sufficient power to assess multiple nutrient and toxic interactions are required to confirm these findings.
Asunto(s)
Catarata/epidemiología , Dieta/estadística & datos numéricos , Compuestos de Metilmercurio/sangre , Selenio/sangre , Contaminantes Químicos del Agua/sangre , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Antioxidantes/metabolismo , Brasil/epidemiología , Exposición a Riesgos Ambientales/análisis , Exposición a Riesgos Ambientales/estadística & datos numéricos , Femenino , Humanos , Modelos Logísticos , Masculino , Compuestos de Metilmercurio/toxicidad , Persona de Mediana Edad , Análisis Multivariante , Oportunidad Relativa , Contaminantes Químicos del Agua/toxicidadRESUMEN
Lead (Pb) is recognized as one of the most toxic metals. Sources of Pb exposure have been widely documented in North America, and the removal of Pb additives from gasoline was reflected in a dramatic lowering of blood Pb concentration. In Latin America, the removal of Pb from gasoline resulted in decreased exposure, but Pb levels in many areas remain high due to occupational and environmental sources of exposure. While many of the Pb sources have been identified (mining, industries, battery recycling, lead-based paint, ceramics), new ones occasionally crop up. Here we report on blood Pb (B-Pb) levels in remote riverside communities of the Brazilian Amazon. Blood Pb (B-Pb) levels were determined in 448 persons from 12 villages of the Lower Tapajós River Basin, Pará, Brazil. Socio-demographic and dietary information, as well as occupational, residential and medical history was collected using an interview-administered questionnaire. B-Pb, measured by ICP-MS, showed elevated concentrations. Mean B-Pb was 13.1 microg/dL +/- 8.5, median B-Pb was 11.2 microg/dL and ranged from 0.59 to 48.3 microg/dL. Men had higher B-Pb compared to women (median: 15.3 microg/dL vs 7.9 microg/dL respectively). B-Pb increased with age for women, while it decreased for men. For both genders, B-Pb decreased with education. There were significant differences between villages. Exploratory analyses, using linear partition models, showed that for men B-Pb was lower among those who were involved in cattle-raising, and higher among those who hunted, farmed and fished. The distribution profile of B-Pb directed us towards artisanal transformation of manioc to flour (farinha), which requires heating in a large metal pan, with stirring primarily done by young men. In the village with the highest B-Pb, analysis of Pb concentrations (dry weight) of manioc (prior to transformation) and farinha (following transformation) from 6 houses showed a tenfold increase in Pb concentration (mean: 0.017 +/- 0.016 to 0.19 +/- 0.10 microg/g). This was confirmed in one of these villages where we sampled manioc paste (just before roasting) and the roasted farinha (0.05 microg/g vs 0.20 microg/g). While there may be other sources (ammunition, sinkers for fishing nets), the high concentrations in farinha, a dietary staple, assuredly makes an important contribution. Further action needs to reduce Pb sources in this region.
Asunto(s)
Exposición a Riesgos Ambientales , Plomo/sangre , Ríos , Brasil , Estudios Transversales , Femenino , Humanos , Masculino , Espectrometría de Masas , Encuestas y CuestionariosRESUMEN
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.
Asunto(s)
Biomarcadores/análisis , Cabello/química , Selenio/análisis , Biomarcadores/sangre , Biomarcadores/orina , Brasil/epidemiología , Demografía , Abastecimiento de Alimentos/estadística & datos numéricos , Ríos , Población Rural , Estaciones del Año , Selenio/sangre , Selenio/orinaRESUMEN
Since deforestation has recently been associated with increased mercury load in the Amazon, the problem of mercury exposure is now much more widespread than initially thought. A previous exploratory study suggested that fruit consumption may reduce mercury exposure. The objectives of the study were to determine the effects of fruit consumption on the relation between fish consumption and bioindicators of mercury (Hg) exposure in Amazonian fish-eating communities. A cross-sectional dietary survey based on a 7-day recall of fish and fruit consumption frequency was conducted within 13 riparian communities from the Tapajós River, Brazilian Amazon. Hair samples were collected from 449 persons, and blood samples were collected from a subset of 225, for total and inorganic mercury determination by atomic absorption spectrometry. On average, participants consumed 6.6 fish meals/week and ate 11 fruits/week. The average blood Hg (BHg) was 57.1 +/- 36.3 microg/L (median: 55.1 microg/L), and the average hair-Hg (HHg) was 16.8 +/- 10.3 microg/g (median: 15.7 microg/g). There was a positive relation between fish consumption and BHg (r = 0.48; P<0.0001), as well as HHg (r =0.34; P<0.0001). Both fish and fruit consumption entered significantly in multivariate models explaining BHg (fish: beta = 5.6, P<0.0001; fruit: beta = -0.5, P = 0.0011; adjusted model R2 = 36.0%) and HHg levels (fish: beta = 1.2, P<0.0001; fruit: beta = -0.2, P = 0.0002; adjusted model R2 = 21.0%). ANCOVA models showed that for the same number of fish meals, persons consuming fruits more frequently had significantly lower blood and HHg concentrations. For low fruit consumers, each fish meal contributed 9.8 microg/L Hg increase in blood compared to only 3.3 microg/L Hg increase for the high fruit consumers. In conclusion, fruit consumption may provide a protective effect for Hg exposure in Amazonian riparians. Prevention strategies that seek to maintain fish consumption while reducing Hg exposure in fish-eating communities should be pursued.