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Biomarkers of mercury exposure in the Amazon.

de Castro NS, Lima Mde O - Biomed Res Int (2014)

Bottom Line: Few studies have focused on the discovery of mercury biomarkers in the region's population.In this way, some studies have used genetics as well as immunological and cytogenetic tools in order to find a molecular biomarker for assessing the toxicological effect of mercury in the Amazonian population.Here we introduce the general aspects involved with each biomarker that was studied in the region in order to contextualize the reader and add information about the Amazonian life style and health that may be considered for future studies.

View Article: PubMed Central - PubMed

Affiliation: Evandro Chagas Institute (IEC), Health Surveillance Secretariat (SVS), 660990 Belém do Pará, PA, Brazil.

ABSTRACT
Mercury exposure in the Amazon has been studied since the 1980s decade and the assessment of human mercury exposure in the Amazon is difficult given that the natural occurrence of this metal is high and the concentration of mercury in biological samples of this population exceeds the standardized value of normality established by WHO. Few studies have focused on the discovery of mercury biomarkers in the region's population. In this way, some studies have used genetics as well as immunological and cytogenetic tools in order to find a molecular biomarker for assessing the toxicological effect of mercury in the Amazonian population. Most of those studies focused attention on the relation between mercury exposure and autoimmunity and, because of that, they will be discussed in more detail. Here we introduce the general aspects involved with each biomarker that was studied in the region in order to contextualize the reader and add information about the Amazonian life style and health that may be considered for future studies. We hope that, in the future, the toxicological studies in this field use high technological tools, such as the next generation sequencing and proteomics skills, in order to comprehend basic questions regarding the metabolic route of mercury in populations that are under constant exposure, such as in the Amazon.

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Related in: MedlinePlus

Correlation between malaria cases reported (a) and mercury levels in hair (b) with positive ANA.
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Related In: Results  -  Collection


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fig1: Correlation between malaria cases reported (a) and mercury levels in hair (b) with positive ANA.

Mentions: The association between exposure to methylmercury from fish consumption and levels of ANA in serum was also investigated by Alves et al. [56]. The sample size was composed by 105 individuals from seven riverine communities that lived in Barcelos, a city in the Rio Negro basin, State of Amazonas. As the main occupational characteristic, they were classified as farmers and fish consumers (99% consume fish daily). Due to these characteristics, those individuals were identified as being exposed to methylmercury. At the time of the study 90.5% of the subjects had a history of malaria (but no prevalence). As inclusion criteria, all selected individuals had a minimum residence time equal to two years and had no clinical symptomatology of chronic diseases. As a control group, 105 blood donors from Manaus were selected, ranging from 18 to 50 years. In this group the patients were identified as low fish consumers with a poor history of malaria infection (5.7%). The riverine population presented higher levels of mercury (35.4 μg/g) in hair than the control group (1.0 μg/g). The results demonstrated a significant correlation between mercury levels in hair and fish consumption. The levels of ANA (≥1 : 40) were analyzed and the positivity among the riverine population was four times higher (12.4%) than in control the group (2.9%). The ANA positivity in Barcelos population has been cited by the authors as similar to Tabatinga population (2%) and Jacareacanga population (3.6%), where individuals were also characterized as higher fish consumers, according to Silva et al. [55]. However, we believe that this assumption may be contradictory, because the levels of ANA in Barcelos population were about four times higher than those of Tabatinga and Jacareacanga, showing a misleading comparison. Actually, ANA levels in the control group (blood donors) are more similar to those observed in Tabatinga and Jacareacanga populations. For comparison, Figure 1 exhibits the data obtained for all the population cited above according to (a) ANA associated with history of malaria and (b) ANA associated with mercury concentration in hair. From the compilation of data presented in Figure 1, the discussion referred to some important questions. (1) Tabatinga, Jacareacanga, and Barcelos populations are high fish consumers. However, the Barcelos population presented higher levels of mercury in hair than the others. Another distinguished feature of Barcelos is that almost all individuals reported past malaria infection. From this point of view, we could inquire: are the highest levels of ANA in Barcelos associated with increased levels of mercury or higher incidence of malaria? (2) The levels of ANA in Tabatinga and Jacareacanga population were similar to the control group (blood donors from Manaus). However, the control group presented the lowest level of mercury on hair. Thus, those results really reflect a correlation between mercury exposure and autoimmune dysfunction or are a reflection of a standard background value for ANA in the Amazonian communities? (3) The study performed at Rio Rato [55] was confronted with a population with high prevalence of malaria. This scenario differs from the other groups investigated (Tabatinga, Jacareacanga, Barcelos, and Blood Donors of Manaus) in which there was not a significant recorded prevalence of individuals with malaria at the time of research. In this way, is it possible to compare the results of ANA in a population with past exposure to malaria with a population that presented prevalent malaria at the time of the survey? In our opinion, it is mandatory to develop specific strategies in order to define the real contribution of malaria and mercury exposure to autoimmune dysfunctions.


Biomarkers of mercury exposure in the Amazon.

de Castro NS, Lima Mde O - Biomed Res Int (2014)

Correlation between malaria cases reported (a) and mercury levels in hair (b) with positive ANA.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4020561&req=5

fig1: Correlation between malaria cases reported (a) and mercury levels in hair (b) with positive ANA.
Mentions: The association between exposure to methylmercury from fish consumption and levels of ANA in serum was also investigated by Alves et al. [56]. The sample size was composed by 105 individuals from seven riverine communities that lived in Barcelos, a city in the Rio Negro basin, State of Amazonas. As the main occupational characteristic, they were classified as farmers and fish consumers (99% consume fish daily). Due to these characteristics, those individuals were identified as being exposed to methylmercury. At the time of the study 90.5% of the subjects had a history of malaria (but no prevalence). As inclusion criteria, all selected individuals had a minimum residence time equal to two years and had no clinical symptomatology of chronic diseases. As a control group, 105 blood donors from Manaus were selected, ranging from 18 to 50 years. In this group the patients were identified as low fish consumers with a poor history of malaria infection (5.7%). The riverine population presented higher levels of mercury (35.4 μg/g) in hair than the control group (1.0 μg/g). The results demonstrated a significant correlation between mercury levels in hair and fish consumption. The levels of ANA (≥1 : 40) were analyzed and the positivity among the riverine population was four times higher (12.4%) than in control the group (2.9%). The ANA positivity in Barcelos population has been cited by the authors as similar to Tabatinga population (2%) and Jacareacanga population (3.6%), where individuals were also characterized as higher fish consumers, according to Silva et al. [55]. However, we believe that this assumption may be contradictory, because the levels of ANA in Barcelos population were about four times higher than those of Tabatinga and Jacareacanga, showing a misleading comparison. Actually, ANA levels in the control group (blood donors) are more similar to those observed in Tabatinga and Jacareacanga populations. For comparison, Figure 1 exhibits the data obtained for all the population cited above according to (a) ANA associated with history of malaria and (b) ANA associated with mercury concentration in hair. From the compilation of data presented in Figure 1, the discussion referred to some important questions. (1) Tabatinga, Jacareacanga, and Barcelos populations are high fish consumers. However, the Barcelos population presented higher levels of mercury in hair than the others. Another distinguished feature of Barcelos is that almost all individuals reported past malaria infection. From this point of view, we could inquire: are the highest levels of ANA in Barcelos associated with increased levels of mercury or higher incidence of malaria? (2) The levels of ANA in Tabatinga and Jacareacanga population were similar to the control group (blood donors from Manaus). However, the control group presented the lowest level of mercury on hair. Thus, those results really reflect a correlation between mercury exposure and autoimmune dysfunction or are a reflection of a standard background value for ANA in the Amazonian communities? (3) The study performed at Rio Rato [55] was confronted with a population with high prevalence of malaria. This scenario differs from the other groups investigated (Tabatinga, Jacareacanga, Barcelos, and Blood Donors of Manaus) in which there was not a significant recorded prevalence of individuals with malaria at the time of research. In this way, is it possible to compare the results of ANA in a population with past exposure to malaria with a population that presented prevalent malaria at the time of the survey? In our opinion, it is mandatory to develop specific strategies in order to define the real contribution of malaria and mercury exposure to autoimmune dysfunctions.

Bottom Line: Few studies have focused on the discovery of mercury biomarkers in the region's population.In this way, some studies have used genetics as well as immunological and cytogenetic tools in order to find a molecular biomarker for assessing the toxicological effect of mercury in the Amazonian population.Here we introduce the general aspects involved with each biomarker that was studied in the region in order to contextualize the reader and add information about the Amazonian life style and health that may be considered for future studies.

View Article: PubMed Central - PubMed

Affiliation: Evandro Chagas Institute (IEC), Health Surveillance Secretariat (SVS), 660990 Belém do Pará, PA, Brazil.

ABSTRACT
Mercury exposure in the Amazon has been studied since the 1980s decade and the assessment of human mercury exposure in the Amazon is difficult given that the natural occurrence of this metal is high and the concentration of mercury in biological samples of this population exceeds the standardized value of normality established by WHO. Few studies have focused on the discovery of mercury biomarkers in the region's population. In this way, some studies have used genetics as well as immunological and cytogenetic tools in order to find a molecular biomarker for assessing the toxicological effect of mercury in the Amazonian population. Most of those studies focused attention on the relation between mercury exposure and autoimmunity and, because of that, they will be discussed in more detail. Here we introduce the general aspects involved with each biomarker that was studied in the region in order to contextualize the reader and add information about the Amazonian life style and health that may be considered for future studies. We hope that, in the future, the toxicological studies in this field use high technological tools, such as the next generation sequencing and proteomics skills, in order to comprehend basic questions regarding the metabolic route of mercury in populations that are under constant exposure, such as in the Amazon.

Show MeSH
Related in: MedlinePlus