Fish consumption, mercury exposure and serum antinuclear antibody in Amazonians

Exposure to intrinsic Hg in fish was studied in Amazon populations with high prevalence of malaria disease. High fish-eater riverines were compared to urban (Manaus residents) low fish-eater riverines in regards to Hg exposure (hair-Hg) and serum antinuclear antibodies (ANA). Most riverines (99.0%) ate fish daily compared to only 3% of controls. Fish species high in MeHg was consumed more frequently (45.5%) by riverines than controls (18.8%). Mean hair-Hg (34.5 ppm) of riverines was significantly higher than controls (1.0 ppm). Although positive serum ANA was more frequently observed in riverine fish-eaters (12.4%) than controls (2.9%), there was no significant association between hair-Hg and ANA. High prevalence of malaria reporting among riverines was neither associated with Hg exposure nor with serum ANA. An autoimmune dysfunction is unlikely to occur as a result of MMHg exposure due to fish consumption.     

A nutritional dilemma: fish consumption,mercury exposure and growth of children in Amazonian Bolivia

To study associations between nutritional status and mercury exposure among communities of the Beni River. Cross-sectional survey of mothers and their children from 15 riverside Amerindian communities in the Beni River valley (Amazonian Bolivia). Hair mercury content (H-Hg) served as a bioindicator of mercury exposure. A total of 556 people were measured. Anthropometric indices of nutrition were calculated after measurements of stature, weight, arm circumference and subcutaneous fat folds. Indicators of lifestyle were collected: subsistence activity, fish consumption and ethnicity. The median of H-Hg was equal to 4.0 μg/g (CI 95%: 3.6 ～ 4.4). There existed a significant relationship between H-Hg and nutritional indices in 5- to 10-year-old children (F = 12.1; p < 0.0001) but not in other age groups. Fishing activity, fish consumption and ethnicity had an effect upon the variance of H-Hg. Positive relationships between nutritional status and H-Hg may be related to the high nutritional value of fish. Among women, the relationship between H-Hg and nutritional status was negative (F = 7.1; p < 0.001), but this disappeared when ethnicity and subsistence activity were taken into account. In these Amazonian communities, recommendations aimed at lowering fish consumption to prevent mercury exposure should be balanced against nutritional advantages conferred upon growing children.     

Selenium and Mercury in the Brazilian Amazon: Opposing Influences on Age-Related Cataracts

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 μg/L).

Objectives

We examined ARCs in relation to these elements among adults (≥ 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 μg/L) and higher blood Hg (B-Hg; ≥ 25th percentile, 25 μg/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.     

Environmental Exposure to Organic Mercury among the Makuxi in the Amazon Basin

Abstract

Gold mining in the savannah region of northern Brazil (Roraima) has increased dramatically since 1989. Elemental mercury is used to extract gold from sediment. Mercury released into the Amazon aquatic ecosystem may convert into the organic form and bioconcentrate in the food chain, posing a hazard for fish-eating peoples such as some of the Makuxi. This survey compared blood organic mercury levels among Makuxi villagers along mined (Rio Cotingo) and unmined (Rio Surumu) rivers. Seventy-five blood samples were obtained from villages who did n ot participate in gold mining or processing procedures in three Makuxi villages: Maravilha (heavily exposed), Limão (limitedly exposed), and Matarucca (minimally exposed ). Blood was analyzed for total and inorganic mercury content by cold vapor spectrophotometry. Mean blood organic mercury levels among the villagers of Maravilha, Limão, and Matarucca were 31. 3 μg/L , 9.3 μg/L , and 2.0 μg/L , respectively (p < 0.001 ). The authors conclude the gold mining process is contarninating the environment of Roraima and may pose a health hazard to its fish-eating populations, such as the Makuxi people.     

Eating tropical fruit reduces mercury exposure from fish consumption in the Brazilian Amazon

This study aimed to examine the influence of the consumption of traditional foods on the relationship between fish consumption and mercury (Hg) exposure. A 12-month prospective dietary survey was carried out with 26 adult women from a fish-eating community in the Brazilian Amazon. Food ingestion was determined using a daily food diary, and total hair Hg levels were assessed for each month through sequential analyses using cold vapor atomic absorption spectrometry. Simple and multiple regression analyses showed that the strong relationship between fish consumption and Hg exposure was significantly modified by fruit consumption: for the same number of fish meals, those who ate more tropical fruits had lower hair mercury levels. The findings of this study indicate different ways of maintaining fish consumption while reducing Hg exposure in the Amazon. A number of phytochemicals and nutritional fibers present in fruits might be interacting with Hg in several ways: absorption and excretion, transport, binding to target proteins, metabolism, and sequestration. More studies are required on larger populations to further elucidate the extent and public health implications of the use of fruits to counteract the toxic action of methylmercury.     

Assessment of mercury exposure and malaria in a Brazilian Amazon riverine community

Small-scale gold mining in the Brazilian Amazon occurs in areas with high rates of malaria transmission. Amazonian populations can be exposed to mercury through direct contact with the mining process and/or through fish consumption. Because of data from experimental studies, we examined the potential for mercury to affect host response to malaria. A cross-sectional survey was done in Jacareacanga, a riverine community in Para state, in a region of intense alluvial gold mining. A sample of 205 persons was selected by cluster sampling from the total population of approximately 2000. A brief medical history and exam were conducted, malaria slides were obtained, and hair samples were taken to measure mercury levels. The average hair mercury level was 8.6 micrograms/g, ranging from 0.3 to 83.2 micrograms/g. The most important predictors of elevated mercury levels were high fish consumption and low income. Although there was no prevalent malaria, the odds of reporting a past malaria infection was four times higher for those also reporting a history of working with mercury.     

Environmental Exposure and Fingernail Analysis of Arsenic and Mercury in Children and Adults in a Nicaraguan Gold Mining Community

Gold mining can release contaminants, including mercury, into the environment, and may increase exposure to naturally occurring elements such as arsenic. The authors investigated environmental and human tissue concentrations of arsenic and mercury in the gold mining town of Siuna, Nicaragua. The study involved 49 randomly selected households in Siuna, from whom a questionnaire along with environmental and fingernail samples were collected. Environmental samples indicated that mercury concentrations in drinking water, although generally low, were higher near the mine site. Arsenic concentrations were elevated in water and soil samples, but their distribution was unrelated to the mining site. Mercury concentrations in fingernail samples were correlated with residential proximity to the mine, drinking water concentrations, occupation, and, among children, with soil concentrations. Fingernail arsenic concentrations correlated with drinking water concentrations among adults who consumed higher levels, and with soil concentrations among children. Fingernail analysis helped to identify differential exposure pathways in children and adults. Mercury and arsenic uptake via soil exposure in children warrants further consideration.     

Challenges with minimising mercury pollution in the small-scale gold mining sector: experiences from the Guianas

This paper examines the barriers to mitigating mercury pollution at small-scale gold mines in the Guianas (Guyana, French Guiana and Suriname), and prescribes recommendations for overcoming these obstacles. Whilst considerable attention has been paid to analysing the environmental impacts of operations in the region, minimal research has been undertaken to identify appropriate policy and educational initiatives for addressing the mounting mercury problem. Findings from recent fieldwork and selected interviews with operators from Guyanese and Surinamese gold mining regions reveal that legislative incapacity, the region's varied industry policy stances, various technological problems, and low environmental awareness on the part of communities are impeding efforts to facilitate improved mercury management at small-scale gold mines in the Guianas. Marked improvements can be achieved, however, if legislation, particularly that pertaining to mercury, is harmonised in the region; educational seminars continue to be held in important mining districts; and additional outlets for disseminating environmental equipment and mercury-free technologies are provided.     

Mercury toxicity in Amazon gold miners: visual dysfunction assessed by retinal and cortical electrophysiology

Amazonian gold mining activity results in human exposure to mercury vapor. We evaluated the visual system of two Amazonian gold miners (29 and 37 years old) by recording the transient pattern electroretinogram (tPERG) and transient pattern visual evoked potential (tPVEP). We compared these results with those obtained from a regional group of control subjects. For both tPERG and tPVEP, checkerboards with 0.5 or 2 cycles per degree (cpd) of spatial frequency were presented in a 16° squared area, 100% Michelson contrast, 50 cd/m² mean luminance, and 1 Hz square-wave pattern-reversal presentation. Two averaged waveforms (n=240 sweeps, 1 s each) were monocularly obtained for each subject in each condition. Both eyes were monocularly tested only in gold miners. Normative data were calculated using a final pooled waveform with 480 sweeps. The first gold miner, LCS, had normal tPERG responses. The second one, RNP, showed low tPERG (P50 component) amplitudes at 0.5 cpd for both eyes, outside the normative data, and absence of response at 2 cpd for his right eye. Delayed tPVEP responses (P100 component) were found at 2 cpd for LCS but the implicit times were inside the normative data. Subject RNP also showed delayed tPVEP responses (all components), but only the implicit time obtained with his right eye was outside the normative data at 2 cpd. We conclude that mercury exposure levels found in the Amazon gold miners is high enough to damage the visual system and can be assessed by non-invasive electrophysiological techniques.     

Infant and fetal mortality among a high fertility and mortality population in the Bolivian Amazon

Indigenous populations experience higher rates of poverty, disease and mortality than non-indigenous populations. To gauge current and future risks among Tsimane Amerindians of Bolivia, I assess mortality rates and growth early in life, and changes in risks due to modernization, based on demographic interviews conducted Sept. 2002–July 2005. Tsimane have high fertility (total fertility rate = 9) and infant mortality (13%). Infections are the leading cause of infant death (55%). Infant mortality is greatest among women who are young, monolingual, space births close together, and live far from town. Infant mortality declined during the period 1990–2002, and a higher rate of reported miscarriages occurred during the 1950–1989 period. Infant deaths are more frequent among those born in the wet season. Infant stunting, underweight and wasting are common (34%, 15% and 12%, respectively) and greatest for low-weight mothers and high parity infants. Regression analysis of infant growth shows minimal regional differences in anthropometrics but greater stunting and underweight during the first two years of life. Males are more likely to be underweight, wasted, and spontaneously aborted. Whereas morbidity and stunting are prevalent in infancy, greater food availability later in life has not yet resulted in chronic diseases (e.g. hypertension, atherosclerosis and diabetes) in adulthood due to the relatively traditional Tsimane lifestyle.     

Assessment of mercury in muscle of fish from Cartagena Bay,a tropical estuary at the north of Colombia

Fish belonging to several trophic levels from Cartagena Bay, a tropical estuary, were collected and analyzed for total mercury (T-Hg) concentrations in muscle. T-Hg concentrations varied from 0.010–0.526 μg/g, and the overall average was 0.051 ± 0.002 μg/g. Carnivorous species presented the highest T-Hg mean value (0.100 ± 0.006 μg/g), followed by omnivorous (0.076 ± 0.014 μg/g) and detritivorous (0.028 ± 0.001 μg/g). The relationships between weight and T-Hg content were found for the carnivorous species Sciades herzbergi (r = 0.508, p < 0.001) and not for the detritivorous Mugil incilis (r = 0.086, p = 0.207). Although results suggest fish from the bay pose a low health threat for humans in terms of Hg exposure, vulnerable groups such as pregnant women, should avoid eating large size carnivorous species. Knowledge about species with low Hg content should be widespread within fishing communities, guaranteeing adequate nutrition by including fish in the diet and reducing the risk of Hg poisoning.     

长期高砷暴露人群砷甲基化与皮肤损害关系的研究

目的探讨长期高砷暴露人群砷代谢差异与砷致皮肤损害之间的关系。方法随机选取某砷污染村庄常住居民327名,进行问卷调查和体格检查。二乙基二硫代氨基甲酸银比色法检测发总砷含量,离子色谱氢化物发生原子荧光法测定尿中四种砷代谢形态。结果发砷含量总体较高,但不同程度皮肤损害的4组间发砷含量差异无显著性;尿中DMA和MMA浓度随着年龄增加有上升的趋势,且与皮肤损害程度呈显著正相关,而无机砷浓度与皮肤损害未见显著相关;重度组人群尿中MMA相对比例显著高于其它3组,而重度组DMA/MMA比值显著低于对照组和轻度组;MMA比例与皮肤损害程度呈显著正相关,DMA/MMA比值与皮肤损害程度呈显著负相关;男性对砷的蓄积能力高于女性,但对砷的甲基化能力低于女性;40岁以上人群对砷的甲基化能力高于40岁以下成人;吸烟者和饮酒者对砷的甲基化代谢水平分别低于非吸烟者和非饮酒者。结论砷在人体内的甲基化代谢水平受性别、年龄、吸烟和饮酒等多因素影响;砷致皮肤损伤程度与砷在体内的甲基化程度有关。     

Evaluation of toxic effects of a diet containing fish contaminated with methylmercury in rats mimicking the exposure in the Amazon riverside population

This study was designed to evaluate the effects of a diet rich in fish contaminated with MeHg, mimicking the typical diet of the Amazon riverside population, in rats. Animals were randomly assigned to one of three groups with eight rats in each group: Group I—control, received commercial ration; Group II—received a diet rich in uncontaminated fish; Group III—received a diet rich in fish contaminated with MeHg. Treatment time was 12 weeks. Oxidative stress markers were evaluated, as well as the effects of this diet on DNA stability, systolic blood pressure (SBP), nitric oxide (NO) levels and histological damage in different tissues. There was a significant increase in SBP values in rats fed with MeHg-contaminated fish diet after the 10th week of the treatment. As far as oxidative stress biomarkers are concerned, no differences were observed in reduced glutathione and protein carbonyl levels, glutathione peroxidase, catalase, superoxide dismutase or δ-aminolevulinate dehydratase activities between the groups of animals receiving contaminated and uncontaminated fish diets. On the other hand, malondialdehyde levels increased significantly in rats fed with contaminated fish. NO levels were similar in all groups. DNA migration showed augmented in rats exposed to contaminated fish and histopathological analyses showed weak but significant leukocyte infiltration. Thus, we conclude that the MeHg-contaminated fish diet induced a slight lipid peroxidation and genotoxicity. However, these effects seem to be much less pronounced than when rats are exposed to aqueous solution containing CH₃HgCl.Our findings support the contention that the chemical form of MeHg in fish or fish nutrients such as polyunsaturated fatty acids, Se or vitamin E could minimize the toxic effects of MeHg exposure in fish-eating communities.     

Temporal variation of blood and hair mercury levels in pregnancy in relation to fish consumption history in a population living along the St. Lawrence River

Fish consumption from the Great Lakes and the St. Lawrence River has been decreasing over the last years due to advisories and increased awareness of the presence of several contaminants. Methylmercury (MeHg), a well-established neurotoxicant even at low levels of exposure, bioaccumulates to differing degrees in various fish species and can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Most studies on MeHg exposure have focussed on high-level consumers from local fish sources, although mercury (Hg) is also present in fresh, frozen, and canned market fish. Moreover, little information exists on the temporal variation of blood and hair Hg in pregnant women, particularly in populations with low levels of Hg. The aim of the present study was to characterize the temporal variation of Hg during pregnancy and to investigate the relation between fish consumption from various sources prior to and during pregnancy and maternal cord blood and mother's hair Hg levels. We recruited 159 pregnant women from Southwest Quebec through two prenatal clinics of the Quebec Public Health System. All women completed two detailed questionnaires concerning their fish consumption (species and frequency) prior to and during pregnancy. The women also provided blood samples for all three trimesters of pregnancy and hair samples after delivery of up to 9 cm in length. Blood and hair Hg levels were analyzed by cold-vapor atomic-absorption and -fluorescence spectrometry methods, respectively. Results showed that maternal blood and hair Hg levels decreased significantly between the second and third trimesters of pregnancy. However, cord blood Hg was significantly higher than maternal blood at birth. Maternal hair was correlated with Hg blood concentration and was highly predictive of the organic fraction in cord blood. A strong dose relation was observed between the frequency of fish consumption before and during pregnancy and Hg exposure in mothers and newborns. Fish consumption prior to and during pregnancy explained 26% and 20% of cord blood Hg variance, respectively. For this population, detailed multivariate analyses showed that during pregnancy market fish (fresh, canned, and frozen) were more important sources of Hg exposure than were fish from the St. Lawrence River. These results should be taken into account for future advisories and intervention strategies, which should consider Hg levels in different species from all sources in order to maximize the nutritional input from fish and minimize the toxic risk.     

Fishing, fish consumption, and awareness about warnings in a university community in central New Jersey in 2007, and comparisons with 2004

Fish are a healthy source of protein, but the risks from consuming fish have become a national concern. Over the past 7 years, there have been a number of national advisories regarding saltwater fish. Fish consumption patterns and public knowledge about advisories and warnings have been examined for at-risk populations, but there is little information about the latter for a general population, or of temporal trends in such information acquisition. Information about the benefits and health risks of consuming fish, health warnings from the New Jersey Department of Environmental Protection and the Food and Drug Administration, belief in these warnings, and trust in different sources of information were examined in a sample of 460 people within a university community in central New Jersey in 2007. The null hypothesis of no differences in fishing, consumption, and knowledge about advisories as a function of age, gender, ethnicity, and education was tested. In 2007, only 30% of the study population fished, and 83% of the study population ate fish, either commercial or self-caught. There were differences in fishing behavior, consumption patterns, and awareness of advisories as a function of gender, ethnicity, age, and education. Most notably, nearly twice as many men as women fished, Whites fished more and Blacks and Indian/Pakistanis fished less than other ethnic groups, and people aged 23-35 fished more than did others. About 8% of fish meals were from self-caught fish, 32% were eaten in restaurants, and 60% were of fish bought in stores and cooked at home. Men ate more meals of self-caught fish than did females, and Asians ate more meals of fish in restaurants, and Blacks ate more meals of store-bought fish than other ethnic groups. The total number of fish meals consumed per month increased significantly with age. Overall, more people had heard about the benefits (92%) than the risks (78%) of fish consumption. When asked whom they trust for information about health benefits and risks from eating fish, doctors were rated the highest, followed by professors; friends and fishermen were rated the lowest. We then examined whether there were any changes from 2004 to 2007 in the knowledge of the health benefits and warnings about fish consumption, and the trustworthiness of different sources of information. In other words, have communication efforts of the state and federal agencies resulted in any appreciable increase in overall awareness of the benefits or risks of fish consumption. The greatest change in the parameters examined from 2004 to 2007 was an overall decrease in fish consumption from an average of 7.9 meals per month in 2004 to about six meals per month in 2007. This suggests that the unintended effect of some of the warnings and advisories is to decrease overall fish consumption, rather than to switch from fish species with high levels of contaminants to those with low levels.     

No evidence for congenital malformations or prenatal death in infants born to women with a high dietary intake of fish contaminated with persistent organochlorines

Objectives: The aim of the present study was to assess whether a high dietary intake of fatty fish from the Baltic Sea, contaminated with persistent organochlorine compounds, might increase the risk for congenital malformations and perinatal death. Methods: A cohort of fishermen's wives from the Swedish east coast (at the Baltic Sea) were linked to the Swedish Medical Birth Register (MBR), resulting in the identification of 1501 infants born in the period 1973–1991. A further linkage with the Swedish Registry of Congenital Malformations was performed. Similar linkages were made for a comparison group of fishermen's wives from the Swedish west coast, who gave birth to 3553 infants during the study period. The reproductive end points studied included congenital malformations, stillbirths, and early neonatal deaths. The expected numbers of these end points were calculated from the MBR data for the regional populations. Results: In the east coast cohort, 3.3% of the infants had some malformation diagnosis as compared with 5.0% of the west coast cohort. As compared with the general population, somewhat fewer malformations than expected were diagnosed in the east coast cohort (risk ratio 0.78, 95% CI 0.58–1.04). No specific malformation was overrepresented in the east coast cohort. The risk ratios for stillbirths and early neonatal deaths did not significantly differ from unity in any of the cohorts. Conclusions: The present results exclude in an unequivocal way an association between exposure to persistent organochlorines from fatty Baltic Sea fish and an increased risk for all congenital malformations and perinatal death. The limited power of the study design, however, does not allow the exclusion of slight risk excesses for some specific types of malformation. Received: 28 May 1998 / Accepted: 22 October 1998     

Relationships of perfluorooctanoate and perfluorooctane sulfonate serum concentrations between mother-child pairs in a population with perfluorooctanoate exposure from drinking water

Background: There are limited data on the associations between maternal or newborn and child exposure to perfluoroalkyl acids (PFAAs), including perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). This study provides an opportunity to assess the association between PFAA concentrations in mother–child pairs in a population exposed to PFOA via drinking water.Objectives: We aimed to determine the relationship between mother–child PFAA serum concentrations and to examine how the child:mother ratio varies with child’s age, child’s sex, drinking-water PFOA concentration, reported bottled water use, and mother’s breast-feeding intention.Methods: We studied 4,943 mother–child pairs (children, 1–19 years of age). The child:mother PFAA ratio was stratified by possible determinants. Results are summarized as geometric mean ratios and correlation coefficients between mother–child pairs, overall and within strata.Results: Child and mother PFOA and PFOS concentrations were correlated (r = 0.82 and 0.26, respectively). Up to about 12 years of age, children had higher serum PFOA concentrations than did their mothers. The highest child:mother PFOA ratio was found among children ≤ 5 years (44% higher than their mothers), which we attribute to in utero exposure and to exposure via breast milk and drinking water. Higher PFOS concentrations in children persisted until at least 19 years of age (42% higher than their mothers). Boys > 5 years of age had significantly higher PFOA and PFOS child:mother ratios than did girls.Conclusion: Concentrations of both PFOA and PFOS tended to be higher in children than in their mothers. This difference persisted until they were about 12 years of age for PFOA and at least 19 years of age for PFOS.