Elisabeth C. de Oliveira Santos

Fetal and maternal immune responses to methylmercury exposure: A cross-sectional study ☆

Methylmercury (MeHg) is a ubiquitous environmental contaminant with known neurodevelopmental effects. In humans, prenatal exposures primarily occur through maternal consumption of contaminated fish. In this study, we evaluated the association between prenatal exposure to MeHg and titers of total immunoglobulins (Ig) and specific autoantibodies in both mothers and fetuses by analyzing maternal and cord blood serum samples. We examined multiple immunoglobulin isotypes to determine if these biomarkers could inform as to fetal or maternal responses since IgG but not IgM can cross the placenta. Finally, we evaluated serum cytokine levels to further characterize the immune response to mercury exposure. The study was conducted using a subset of serum samples (N=61 pairs) collected from individuals enrolled in a population surveillance of MeHg exposures in the Brazilian Amazon during 2000/2001. Serum titers of antinuclear and antinucleolar autoantibodies were measured by indirect immunofluorescence. Serum immunoglobulins were measured by enzyme-linked immunosorbent assay (ELISA) and BioPlex multiplex assay. Serum cytokines were measured by BioPlex multiplex assay. In this population, the geometric mean mercury level was within the 95th percentile for US populations of women of childbearing age but the upper level of the range was significantly higher. Fetal blood mercury levels were higher (1.35 times) than those in their mothers, but highly correlated (correlation coefficient [r]=0.71; 95% CI: 0.54, 0.89). Total IgG (r=0.40; 95% CI: 0.19, 0.62) and antinuclear autoantibody (odds ratio [OR]=1.05; 95% CI: 1.02, 1.08) levels in paired maternal and fetal samples were also associated; in contrast, other immunoglobulin (IgM, IgE, and IgA) levels were not associated between pairs. Total IgG levels were significantly correlated with both maternal (r=0.60; 95% CI: 0.25, 0.96) and cord blood mercury levels (r=0.61; 95% CI: 0.25, 0.97), but individual isotypes were not. Serum cytokines, interleukin-1β (r=0.37; 95% CI: 0.01, 0.73), interleukin-6 (r=0.34; 95% CI: 0.03, 0.65), and tumor necrosis factor-α (r=0.24; 95% CI: 0.015, 0.47), were positively correlated between maternal and fetal samples. Antinuclear and antinucleolar autoantibody titer and serum cytokine levels, in either maternal or cord blood, were not significantly associated with either maternal or cord blood mercury levels. These data provide further evidence that there are likely IgG biomarkers of mercury-induced immunotoxicity in this population since IgG levels were elevated with increased, and associated with, mercury exposure. However, unlike previous data from adult males and non-pregnant females, we found no evidence that antinuclear and antinucleolar autoantibody titer is a reliable biomarker of mercury immunotoxicity in this population.

Correlation between blood mercury levels in mothers and newborns in Itaituba, Pará State, Brazil

This study evaluated transplacental mercury transfer by measuring Hg in blood samples of mothers and newborns (umbilical cord) in hospitals in the municipality (county) of Itaituba, Pará State, Brazil. Epidemiological and mercury exposure data were collected, besides clinical birth data. Mercury tests were performed by cold-vapor atomic absorption spectrophotometry. A total of 1,510 women and an equal number of their newborns participated in the study. Mean blood mercury was 11.53 microg/L in mothers and 16.68 microg/L in newborns (umbilical cord). The highest Hg levels were in the 31-40-year maternal age group and their newborns, with 14.37 microg/L and 21.87 microg/L, respectively. However, in all age groups the mean mercury level was higher in newborns than in mothers. There was a strong positive correlation between Hg levels in newborns and mothers (r = 0.8019; p = 0.000), with a significant linear regression model (r = 0.5283; p = 0.000). The results highlight the importance of monitoring pregnant women exposed to mercury as part of public health surveillance.

Exposição ao mercúrio e ao arsênio em Estados da Amazônia: síntese dos estudos do Instituto Evandro Chagas/ FUNASA

Este artigo e uma revisao das pesquisas da Secao de Meio Ambiente do Instituto Evandro Chagas/FUNASA sobre exposicao ao mercurio (Hg) no vale do rio Tapajos e Estado do Acre, e exposicao ao arsenio (As) atraves de residuos da exploracao de manganes (Mn) realizada pela ICOMI deixados no Porto de Santana-AP. Em relacao ao mercurio, tem sido pesquisadas populacoes sob risco atraves da via respiratoria ou alimentar. No primeiro caso, os trabalhadores de casas de compra e venda de ouro tem apresentado teores mais elevados de Hg em urina do que os garimpeiros estudados. No segundo caso, as populacoes ribeirinhas tem mostrado niveis diferenciados de exposicao (Hg em cabelo). Comunidades ribeirinhas situadas em areas nao afetadas pelo mercurio da garimpagem e com habitos alimentares semelhantes as de area de risco tem sido avaliadas, visando a construcao de parâmetros de normalidade regional. Sao tambem pesquisados os teores de Hg em materiais ambientais e na biota aquatica. Os estudos de saude humana e ambiente na cidade de Santana-AP objetivaram avaliar as fontes e possiveis vias de exposicao da populacao da comunidade do Elesbao ao arsenio. Verificou-se a existencia de fonte de risco atraves dos rejeitos de Mn, porem os niveis de As na agua consumida pela populacao mostraram-se dentro dos parâmetros de normalidade. As medias encontradas em sangue e cabelo coincidem com medias de normalidade referidas na literatura, em populacoes nao expostas, e as associacoes entre variaveis epidemiologicas, avaliacao clinico-laboratorial e os teores de arsenio nao mostraram significância estatistica.

Mercury levels assessment in hair of riverside inhabitants of the Tapajós River, Pará State, Amazon, Brazil: Fish consumption as a possible route of exposure

The study present evaluated the levels of mercury (Hg) and methylmercury (MeHg) in hair samples of people from Barreiras community, riverside inhabitants of the Tapajós River (Pará, Brazil), an area impacted by clandestine gold mining, as well as we analyzed the levels of Hg and Se (selenium) in nine fish species (carnivores and non-carnivorous) from the Tapajós River, which stand out as the main species consumed by riverside inhabitants, to evaluate a relationship between frequency of fish consumption and Hg concentration, and also to evaluate possible mechanisms of fish protection (or non-protection) to Hg exposure by Se. Furthermore we analyze the water quality to evaluate the environmental trophic state, fact responsible by creating conditions that can potentiate the effects of toxic mercury. Concentrations of Hg and MeHg were analyzed in hair samples of 141 volunteers in different age band. Of those, 84.40% of samples present values above the threshold for biological tolerance, which is 6.00μgg(-1) of total Hg in hair. Total Hg, in men there was a variation of 2.07-24.93μgg(-1), while for women the variation was 4.84-27.02μgg(-1). Consequently, the level of MeHg in men presented a variation of 1.49-19.57μgg(-1), with an average of 11.68μgg(-1), while with women the variation was from 3.73 to 22.35μgg(-1), with an average of 10.38μgg(-1). In fish species, Hg concentrations in carnivorous species had an average of 0.66μgg(-1), higher than that permitted by current legislation, ranging from 0.30 to 0.98μgg(-1), while the non-carnivorous species have values below the recommended by the legislation averaging 0.09μgg(-1), ranging between 0.02 and 0.44μgg(-1). For Se in fish, show that among carnivores, the contents of Se ranged between 0.18 and 0.54μgg(-1) with a mean of 0.34μgg(-1), while for non-carnivores these values were of the order of 0.16-0.56μgg(-1), with an average of 0.32μgg(-1). In surface water quality variables at the sampling points all showed values in accordance with the range established by current legislation. In this regard, the results provided by this study, while not conclusive, are strong indicators that despite not having been shown the relationship between the concentration of mercury in hair and feeding habits along the Tapajós River basin communities showed that a plausible correlation exists between levels of mercury and selenium in fish. This fact may serve as a subsidy to research human health, because in the Amazon, there is still a lot to examine with regards to the full understanding of the Se cycle.

Avaliação da concentração de mercúrio em sedimentos e material particulado no rio Acre, estado do Acre, Brasil

Mercury levels assessment in aquatic systems areas without influences of antropogenic sources have not been well studied in the Amazon region. For the identification of the origin of high values of Hg in fish consumed by population of Rio Branco City - AC, the Evandro Chagas Institute - IEC, studied the mercury levels in sediments, suspended solids and studied also the physical-chemical characterization of waters, in the Acre river and also some in afluents, between Brasileia and Assis Brasil cities. Bottom sediments samples were sieved to <250 mesh fraction after drying. The suspended solid was obtained by precipitation with Al2SO4. About 250 mg of the material was submitted the acid digestion and the determinations of Hg were made by Could Vapor Atomic Absorption Spectrometry. The physical-chemical parameters pH, electric conductivity, temperature and dissolved total solids, were studied in the field, by potenciometric methods. The Hg levels in bottom sediments range 0,018 and 0,184 mg g-1, mean of 0,054 ± 0,034 mg g-1, while the suspended solids varied between 0,067 and 0,220 mg g-1, average of 0,098 ± 0,037 mg g-1. The waters were slightly acid with pH varying among 5,80 - 6,95 and conductivity electric 151,60 - 1.151,00 mS cm-1. The mercury levels in the analyzed materials was below of standard levels for the non-polluted Amazon rivers. However complementary studies should be developed to elucidate the origin and the processes of mercury biodisponibility.

Avaliação dos níveis de exposição ao mercúrio entre índios Pakaanóva, Amazônia, Brasil

Um estudo seccional foi realizado para avaliar os niveis de exposicao ao mercurio (Hg) entre 910 indios Pakaanova, residentes nos municipios de Guajara Mirim e Nova Marmore no Estado de Rondonia, Brasil. Amostras de cabelo da regiao occipital foram coletadas de cada participante do estudo e os teores de Hg determinados por Espectrofotometria de Absorcao Atomica com Geracao de Vapor Frio. Os teores medios de Hg nas amostras de cabelo foram de 8,37µg/g (0,52-83,89µg/g), indicando exposicao elevada. Criancas de ate 2 anos e entre 3 e 5 anos de idade apresentaram medias de 10,54µg/g e 9,34µg/g, respectivamente. Os teores medios de Hg nas mulheres (8,91µg/g ) sao mais elevados do que os valores observados nos homens (7,55µg/g), sendo esta diferenca estatisticamente significante (t = 3,26; p < 0,01). Estes resultados indicam a necessidade de desenvolvimento de programas de vigilância e estudos complementares envolvendo os indios Pakaanova no Estado de Rondonia.A cross-sectional study was conducted to evaluate mercury (Hg) exposure among 910 Pakaanova Indians from the counties of Guajara Mirim and Nova Marmore, Rondonia State, Brazil. Individual hair samples were taken from the occipital region, and Hg was measured by atomic absorption spectrometry with cold vapor generation. Mean Hg in hair samples was 8.37 µg/g (range 0.52-83.89), indicating high exposure. Young children (< 2 years old) showed a mean Hg of 10.54 µg/g, and children from 3 to 5 years old had a mean Hg of 9.34µg/g. Mercury levels in women (8,91µg/g) were higher than in men (7.55µg/g), and this difference was significant (t = 3.26; p < 0.01). These results indicate the need for surveillance programs and complementary studies including the Pakaanova Indians in Rondonia State.

Mercury Speciation in Hair of Children in Three Communities of the Amazon, Brazil

Children from riverside communities located downstream of gold mining areas may be chronically exposed to relatively high levels of MeHg through the consumption of fish of this region. The objective of this study was to evaluate and compare levels of THg and MeHg in hair of children less than 12 years in communities near mines in the municipality of Itaituba and in communities far from prospecting areas in the city of Abaetetuba. The communities of Itaituba (Barreiras and São Luiz do Tapajós) had THg mean levels of 5.64 ± 5.55 μg·g−1 (0.43–27.82) and 11.41 ± 7.16 μg.g−1 (1.08–28.17), respectively, and an average count of MeHg relative to THg of 92.20% and 90.27%, respectively. In the Maranhão community, the THg average concentrations results were 2.27 ± 2.11 μg·g−1 (0.13–9.54) and the average values were 93.17% for MeHg. Children of Itaituba had average levels of mercury above the limit established by the World Health Organization (10 μg·g−1) and the strong correlation coefficient between the communities (R = 0.968 and P = 0.0001) suggests the hair as an excellent biomarker of human exposure to organic mercury in riverside populations of the Tapajós, which has the intake of fish daily as main source of protein dietary.

Genome-wide study of the defective sucrose fermenter strain of Vibrio cholerae from the Latin American cholera epidemic

The 7th cholera pandemic reached Latin America in 1991, spreading from Peru to virtually all Latin American countries. During the late epidemic period, a strain that failed to ferment sucrose dominated cholera outbreaks in the Northern Brazilian Amazon region. In order to understand the genomic characteristics and the determinants of this altered sucrose fermenting phenotype, the genome of the strain IEC224 was sequenced. This paper reports a broad genomic study of this strain, showing its correlation with the major epidemic lineage. The potentially mobile genomic regions are shown to possess GC content deviation, and harbor the main V. cholera virulence genes. A novel bioinformatic approach was applied in order to identify the putative functions of hypothetical proteins, and was compared with the automatic annotation by RAST. The genome of a large bacteriophage was found to be integrated to the IEC224s alanine aminopeptidase gene. The presence of this phage is shown to be a common characteristic of the El Tor strains from the Latin American epidemic, as well as its putative ancestor from Angola. The defective sucrose fermenting phenotype is shown to be due to a single nucleotide insertion in the V. cholerae sucrose-specific transportation gene. This frame-shift mutation truncated a membrane protein, altering its structural pore-like conformation. Further, the identification of a common bacteriophage reinforces both the monophyletic and African-Origin hypotheses for the main causative agent of the 1991 Latin America cholera epidemics.

Assessment of surface water in two Amazonian rivers impacted by industrial wastewater, Barcarena City, Pará State (Brazil)

In 2007, surface waters were collected from 21 sampling points in Barcarena City in Northern Region of Brazil: one sampling point located in a stream that receives discharge of wastewater from a kaolin processing industry and flows into the Curupere River, three sampling points located near sources that emerge on the left bank and flow into the Curupere River, nine sampling points in Curupere River, which flows into the Dende River, and eight in Dende River, a tributary on the right bank of the Para River. For all water samples were quantified 14 physicochemical variables and levels of 12 metals. The results in the points near the sources of the Curupere River presented physicochemical profile and metal levels which are typical of surface waters being used as reference to compare and identify possible changes in the chemical characteristics of the other sampling points. The comparison between the results obtained for the sources of the Curupere River and the ones for the point near the discharge of industrial wastewater revealed strong changes in the values of 6 physicochemical variables (pH, electrical conductivity (EC), total dissolved solids (TDS), sulfate (SO4), ammoniacal nitrogen (NH4-N) and salinity) and an increase in magnitude of the levels of four metals (Al, Fe, Mn and Zn). These facts characterized that the wastewaters were discharged into the environment without adequate treatment. Results in other sampling sites showed that these anomalous conditions were also found along the Curupere and Dende Rivers, especially during low tide. This chemical characterization of the waters allowed to identify harmful conditions to aquatic ecosystems and potential health risk for the local people, who use the rivers for drinking water, recreation and transportation.

Complete Genome Sequence of a Sucrose-Nonfermenting Epidemic Strain of Vibrio cholerae O1 from Brazil

We report the genome sequence of Vibrio cholerae strain IEC224, which fails to ferment sucrose. It was isolated from a cholera outbreak in the Amazon. The defective sucrose phenotype was determined to be due to a frameshift mutation, and a molecular marker of the Latin American main epidemic lineage was identified.