Elevated blood lead levels in a riverside population in the Brazilian Amazon

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 Tapajos River Basin, Par, 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 mu g/dL +/- 8.5, median B-Pb was 11.2 mu g/dL and ranged from 0.59 to 48.3 mu g/dL. Men had higher B-Pb compared to women (median: 15.3 mu g/dL vs 7.9 mu g/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 mu g/g). This was confirmed in one of these villages where we sampled manioc paste Oust before roasting) and the roasted farinha (0.05 mu g/g vs 0.20 mu g/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. (C) 2009 Elsevier Inc. All rights reserved.

Determination of total and inorganic mercury in whole blood by cold vapor inductively coupled plasma mass spectrometry (CV ICP-MS) with alkaline sample preparation

A simple method with a fast sample preparation procedure for total and inorganic mercury determinations in blood samples is proposed based on flow injection cold vapor inductively coupled plasma mass spectrometry (FI-CVICP-MS). Aliquots of whole blood (500 mL) are diluted 1 + 1 v/v with 10.0% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 3 h at room temperature and then further diluted 1 + 4 v/v with 2.0% v/v HCl. The inorganic Hg was released by online addition of L-cysteine and then reduced to elemental Hg by SnCl(2). On the other hand, total mercury was determined by on-line addition of KMnO(4) and then reduced to elemental Hg by NaBH(4). Samples were calibrated against matrix-matching. The method detection limit was found to be 0.80 mu g L(-1) and 0.08 mu g L(-1) for inorganic and total mercury, respectively. Sample throughput is 20 samples h(-1). The method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from the National Institute of Standards and Technology (NIST). For additional validation purposes, human whole blood samples were analyzed by the proposed method and by an established CV AAS method, with no statistical difference between the two techniques at 95% confidence level on applying the t-test.

Protective properties of quercetin against DNA damage and oxidative stress induced by methylmercury in rats

Aim of the study was to find out whether consumption of quercetin (QC), an abundant flavonoid in the human diet, protects against DNA damage caused by exposure to organic mercury. Therefore, rats were treated orally with methylmercury (MeHg) and the flavonoid with doses that reflect the human exposure. The animals received MeHg (30 mu g/kg/bw/day), QC (0.5-50 mg/kg/bw/day), or combinations of both over 45 days. Subsequently, the glutathione levels (GSH) and the activities of glutathione peroxidase (GPx) and catalase (CAT) were determined, and DNA damage was measured in hepatocytes and peripheral leukocytes in single cell gel electrophoresis assays. MeHg decreased the concentration of GSH and the activity of GPx by 17 and 12%, respectively and caused DNA damage to liver and blood cells, while with QC no such effects were seen. When the flavonoid was given in combination with MeHg, the intermediate and the highest concentrations (5.0 and 50.0 mg/kg/bw/day) were found to cause DNA protection; DNA migration was reduced by 54 and 65% in the hepatocytes and by 27 and 36% in the leukocytes; furthermore, the reduction in GSH and GPx levels caused by MeHg treatment was restored. In summary, our results indicate that consumption of QC-rich foods may protect Hg-exposed humans against the adverse health effects of the metal.

Mercury speciation in seafood samples by LC-ICP-MS with a rapid ultrasound-assisted extraction procedure: Application to the determination of mercury in Brazilian seafood samples

This paper describes a simple method for mercury speciation in seafood samples by LC-ICP-MS with a fast sample preparation procedure. Prior to analysis, mercury species were extracted from food samples with a solution containing mercaptoethanol, L-cysteine and HCl and sonication for 15 min. Separation of mercury species was accomplished in less than 5 min on a C8 reverse phase column with a mobile phase containing 0.05%-v/v mercaptoethanol, 0.4% m/v L-cysteine and 0.06 mol L(-1) ammonium acetate. The method detection limits were found to be 0.25, 0.20 and 0.1 ng g(-1) for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Certified Reference Materials (DOLT-3 and DORM-3) from the National Research Council Canada (NRCC). With the proposed method there is a considerable reduction of the time of sample preparation. Finally, the method was applied for the speciation of mercury in seafood samples purchased from the Brazilian market. (C) 2010 Elsevier Ltd. All rights reserved.

Evaluation of protective effects of fish oil against oxidative damage in rats exposed to methylmercury

The present study evaluates a possible protective effect of fish oil against oxidative damage promoted by methylmercury (MeHg) in sub-chronically exposed rats. Reduced glutathione peroxidase and catalase enzyme activity and reduced glutathione levels were observed in MeHg-exposed animals compared to controls. Methylmercury exposure was also associated with DNA damage. Administration of fish oil to the methylmercury-exposed animals did not ameliorate enzyme activity or glutathione levels. On the other hand, a significant DNA protective effect (about 30%) was observed with fish oil treatment. There were no differences in the total mercury concentration in rat liver, kidney, heart or brain after MeHg administration with or without fish oil co-administration. Histopathological analyses showed a significant leukocyte infiltration in rat tissues after MeHg exposure, but this effect was significantly reduced after co-administration of fish oil. Taken together, our findings demonstrate oxidative damage even after low-level MeHg exposure and the protective effect of fish oil. This protection seems not to be related to antioxidant defenses or mercury re-distribution in rat tissues. It is probably due to the anti-inflammatory effects of fish oil. (C) 2010 Elsevier Inc. All rights reserved.

Mercury speciation in whole blood by gas chromatography coupled to ICP-MS with a fast microwave-assisted sample preparation procedure

A simple and fast method is described for simultaneous determination of methylmercury (MeHg), ethylmercury (Et-Hg) and inorganic mercury (Ino-Hg) in blood samples by using capillary gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) after derivatization and alkaline digestion. Closed-vessel microwave assisted digestion conditions with tetramethylammonium hydroxide (TMAH) have been optimized. Derivatization by using ethylation and propylation procedures have also been evaluated and compared. The absolute detection limits (using a 1 mu L injection) obtained by GC-ICP-MS with ethylation were 40 fg for MeHg and Ino-Hg, respectively, and with propylation were 50, 20 and 50 fg for MeHg, Et-Hg and Ino-Hg, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from the National Institute of Standards and Technology (NIST). Additional validation is provided based on the comparison of results obtained for mercury speciation in blood samples with the proposed procedure and with a previously reported LC-ICP-MS method. With the new proposed procedure no tedious clean-up steps are required and a considerable improvement of the time of analysis was achieved compared to other methods using GC separation.

Elevated levels of selenium in the typical diet of Amazonian riverside populations

Selenium (Se) intake is generally from food, whose Se content depends on soil Se and plant accumulation. For humans, adequate Se intake is essential for several selenoenzymes. In the Lower Tapajos region of the Brazilian Amazon, Se status is elevated with large inter-community variability. Se intake in this region, where Hg exposure is among the highest in the world, may be important to counteract mercury (Hg) toxicity. The present study was conducted in 2006 with 155 persons from four communities of the Lower Tapajos. The objectives were: i) to evaluate Se content in their typical diet and drinking water; ii) to compare food Se concentrations with respect to geographic location; and iii) to examine the contribution of consumption of different food items to blood Se. More than 400 local foods and 40 drinking water samples were collected. Participants responded to an interview-administered food frequency questionnaire and provided blood samples. Food, water and blood Se levels were assessed by ICP-MS. Since Brazil nuts may also contain significant levels of barium (Ba) and strontium (Sr), these elements were likewise analyzed in nuts. The highest Se concentrations were found in Brazil nuts, but concentrations were highly variable (median: 13.9 mu g/g; range: 0.4-158.4 mu g/g). Chicken, game meat, eggs and beef also contained considerable levels of Se, with median concentrations from 0.3 to 1.4 mu g/g. There was no particular geographic distribution of food Se. Se concentration in drinking water was very low (<1.4 mu g/L). Blood Se covered a (103-1500 mu g/L), and was positively related to regular consumption of Brazil nuts, domestic chicken and game meat. Brazil nuts were found to contain highly variable and often very high concentrations of Ba (88.0 mu g/g, 1.9-1437 mu g/g) and Sr (38.7 mu g/g, 3.3-173 mu g/g). Further studies should address multiple nutrient/toxic interactions in the diet and related effects on health. (c) 2010 Elsevier B.V. All rights reserved.

Exposure to contaminated water: perceptions and practices in a neighborhood in the city of Manaus, Brazil

Objective. To investigate the modes of water supply and the perception concerning the problems caused by this water among residents of a neighborhood without public supply of water, settled in an area previously used as a garbage dump in the city of Manaus, Brazil. Methods. One hundred and sixty-two semi-structured household interviews were conducted. In addition, a focal group with teachers from a local public school and a meeting with residents were held. The instruments employed focused on the perception and modes of water use and on the process of exposure to chemical contaminants through water. Results. Untreated well water was used by most families. This water was considered to be ""good"" by 64.8% of the individuals interviewed. Most residents (88.3%) declared knowledge about the garbage dump. Of these, 77.6% stated that the garbage dump caused health and environmental problems. However, qualitative analysis of the responses revealed that the residents were not aware of contamination by chemical elements or of the consequences of such contamination. The activities carried out with teachers revealed that they were partially aware of the problem, but did not design interventions to address the issue. In a meeting with neighborhood residents, the presence of social activism concerning the problem was identified, but it did not extend beyond the neighborhood or reach governmental spheres. Conclusions. The study identified a situation of critical exposure that tends to be maintained as a result of misperceptions and lack of social mobilization. The dissemination of research results to teachers and residents was useful to empower subjects.

Knowing your allies: Medical education and interprofessional exposure

Collaborative, team-based, interprofessional approaches to patient management are becoming increasingly recognized as beneficial to health outcomes. This project aimed to develop interprofessional skills among 134 third year medical students that were of clinical educational value to the students, and through activities that directly benefited the rural health professionals in their daily work. Placements were undertaken during a six week rural clinical attachment, mainly throughout South-West Queensland. Pre- and post-placement self-report questionnaires completed by both students and health professionals were used to evaluate the project. Results showed that over 80% of the health professional group reported the medical student placements were useful. Similarly, almost 80% of medical students reported positive changes in their attitude to other health professionals from the placement, and 91% indicated they had derived clinical educational benefit from their interprofessional activity. Despite difficulties due to poor communication between the various parties involved, the project proved successful in improving medical students' skills, knowledge and perceptions concerning interprofessional practice, through a placement and educational project which delivered practical benefits to rural health professionals and rural communities.

Coronary events and exposure to environmental tobacco smoke: a case-control study from Australia and New Zealand

Objectives-To estimate the relative risk of coronary heart disease (CHD) associated with exposure to environmental tobacco smoke (ETS). Design-Population-based case-control study. Subjects-Cases were 953 people identified in a population register of coronary events, and controls were 3189 participants in independent community-based risk factor prevalence surveys from the same study populations. Setting-Newcastle, Australia and Auckland, New Zealand. Main outcome measures-Acute myocardial infarction or coronary death. Results-After adjusting for the effects of age, education, history of heart disease, and body mass index, women had a statistically significant increased risk of a coronary event associated with exposure to ETS (relative risk (RR) = 1.99; 95% confidence interval (CI)= 1.40-2.81). There was little statistical evidence of increased risk found in men (RR = 1.02, 95% CI = 0.81-1.28). Conclusion-Our study found evidence for the adverse effects of exposure to ETS on risk of coronary heart disease among women, especially at home. For men the issue is unclear according to the data from our study. Additional studies with detailed information on possible confounders and adequate statistical power are needed. Most importantly, they should use methods for measuring exposure to ETS that are sufficiently accurate to permit the investigation of dose-response relationships.

Chronic ethanol exposure and withdrawal influence NMDA receptor subunit and splice variant mRNA expression in the rat cerebral cortex

Chronic ethanol exposure and subsequent withdrawal are known to change NMDA receptor activity. This study examined the effects of chronic ethanol administration and withdrawal on the expression of several NMDA receptor subunit and splice variant mRNAs in the rat cerebral cortex. Ethanol dependence was induced by ethanol vapour exposure. To delineate between seizure-induced changes in expression during withdrawal and those due to withdrawal per se, another group of naive rats was treated with pentylenetetrazol (PTZ) injection (30 mg/kg, i.p.). RNA samples from the cortices of chronically treated and withdrawing animals were compared to those from pairfed controls. Changes in NMDA receptor mRNA expression were determined using ribonuclease protection assays targetting the NR2A, -2B, -2C and NR1-pan subunits as well as the three alternatively spliced NR1 inserts (NR1-pan describes all the known NR1 splice variants generated from the 5' insert and the two 3' inserts). The ratio of NR1 mRNA incorporating the 5' insert vs, that lacking it was decreased during ethanol exposure and up to 48 h after withdrawal. NR2B mRNA expression was elevated during exposure, but returned to control levels 18 h after withdrawal. Levels of NR2A, NR2C, NR1-pan and both 3' NR1 insert mRNAs from the ethanol-treated groups did not alter compared with the pair-fed control group. No changes in the level of any NMDA receptor subunit mRNA was detected in the PTZ-treated animals. These data support the hypothesis that changes in NMDA receptor subunit composition may underlie a neuronal adaptation to the chronic ethanol-inhibition and may therefore be important in the precipitation of withdrawal hyperactivity. (C) 1999 Elsevier Science B.V. All rights reserved.

Neurons in the hilus region of the rat hippocampus are depleted in number by exposure to alcohol during early postnatal life

We have previously shown that exposing rats to a relatively high dose of ethanol during early postnatal life resulted in a deficit in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rats to ethanol during early postnatal life affected the number of specific neurons in the hippocampus. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 and 15 by placing them for 3 h each day in a chamber containing ethanol vapor. The blood ethanol concentration was about 430 mg/dl at the end of the exposure period. Groups of ethanol-treated (ET) rats, separation controls (SC), and mother-reared controls (MRC) were anesthetized and killed at 16 days of age by perfusion with phosphate-buffered glutaraldehyde (2.5%). The Cavalieri principle was used to determine the volume of various subdivisions of the hippocampal formation (CA1, CA2+CA3, hilus, and granule cell layer), and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There were, on average, about 441,000 granule cells in the granule cell layer and 153,000 to 177,000 pyramidal cells in both the CA1 and CA2+CA3 regions in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This was significantly fewer than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. Thus, neurons in the hilus region may be particularly vulnerable to the effects of a high dose of ethanol exposure during early postnatal life. (C) 2000 Wiley-Liss, Inc.

Exposure of rats to a high but not low dose of ethanol during early postnatal life increases the rate of loss of optic nerve axons and decreases the rate of myelination

Visual system abnormalities are commonly encountered in the fetal alcohol syndrome although the level of exposure at which they become manifest is uncertain. In this study we have examined the effects of either low (ETLD) or high dose (ETHD) ethanol, given between postnatal days 4-9, on the axons of the rat optic nerve. Rats were exposed to ethanol vapour in a special chamber for a period of 3 h per day during the treatment period. The blood alcohol concentration in the ETLD animals averaged similar to 171 mg/dl and in the ETHD animals similar to 430 mg/dl at the end of the treatment on any given day. Groups of 10 and 30-d-old mother-reared control (MRC), separation control (SC), ETLD and ETHD rats were anaesthetised with an intraperitoneal injection or ketamine and xylazine, and killed by intracardiac perfusion with phosphate-buffered glutaraldehyde. In the 10-d-old rat optic nerves there was a total of similar to 145000-165000 axons in MRC, SC and ETLD animals. About 4 % of these fibres were myelinated. The differences between these groups were not statistically significant. However, the 10-d-old ETHD animals had only about 75000 optic nerve axone (P < 0.05) of which about 2.8 % were myelinated. By 30 d of age there was a total of between 75000 90000 optic nerve axons, irrespective of the group examined. The proportion of axons which were myelinated at this age was still significantly lower (P < 0.001) in the ETHD animals (similar to 77 %) than in the other groups (about 98 %). It is concluded that the normal stages of development and maturation of the rat optic nerve axons, as assessed in this study, can be severely compromised by exposure to a relatively high (but not low) dose of ethanol between postnatal d 4 and 9.