Analysis of genetic susceptibility to mercury contamination evaluated through molecular biomarkers in at-risk Amazon Amerindian populations

Abstract

We investigated Individual differences in susceptibility to methylmercury (MeHg) contamination and its relationship with polymorphisms of the detoxifying enzyme glutathione S-transferase (GST). In Brazil, some Amerindian tribes from the Amazon region have an increased level of mercury in their hair. Samples of hair and blood were taken from inhabitants of two villages in the Kayabi and Munduruku Amerindian communities to investigate mercury levels in association with genetic polymorphism of GSTs. Other molecular biological markers were also studied, such as hemoglobin, haptoglobin and glucose 6-phosphate dehydrogenase (G-6-PDH). Higher levels of mercury contamination were found in the Kayabi villagers, who had a null genotype (GSTM1 0/0, also denominated GSTM1 null) frequency of 26%, than in the Munduruku villagers, for which the null genotype frequency was 0%. Individuals with the GSTM1 null phenotype had higher concentrations of mercury in their hair than individuals with GSTM1+/+ phenotypes (F = 21.51, p < 0.0001). No association with other markers studied was observed. This study suggests that GSTM1 may be involved in the biotransformation of mercury in humans.

Mercury as undesirable substance in animal feed - Scientific opinion of the Panel on Contaminants in the Food Chain

“…Higher levels of mercury contamination in the hair have been found in human populations harbouring a null glutathione S-transferase (GST) genotype (GSTM1 0/0) (26% frequency) when compared with the counterpart population for which the null genotype frequency was 0%. This study and others (Klautau-Guimarães et al, 2005;Gundacker et al, 2007) suggests that GSTs polymorphism plays an important role in the disposition of mercury in humans.…”

Hair as a Biomarker of Long Term Mercury Exposure in Brazilian Amazon: A Systematic Review

“…According to the year of publication, the articles were published as follows: three in 1998 [ 16 , 17 , 18 ], two in 1999 [ 19 , 20 ], three in 2000 [ 21 , 22 , 23 ], two in 2001 [ 24 , 25 ], one in 2002 [ 26 ], two in 2003 [ 27 , 28 ], four in 2005 [ 29 , 30 , 31 , 32 ], three in 2006 [ 33 , 34 , 35 ], two in 2007 [ 36 , 37 ], one in 2008 [ 38 ], one in 2009 [ 39 ], two in 2010 [ 40 , 41 ], three in 2012 [ 42 , 43 , 44 ], one in 2013 [ 45 ], one in 2014 [ 46 ], three in 2015 [ 47 , 48 , 49 ] and two in 2016 [ 50 , 51 ]. Most of the studies (61%) were performed exclusively by Brazilians Institution [ 16 , 18 , 20 , 21 , 22 , 24 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 37 , 41 , 42 , 43 ,…”

“…There was a predominance of studies that were performed in the State of Pará (47%) [ 22 , 23 , 25 , 26 , 27 , 29 , 35 , 36 , 37 , 38 , 39 , 40 , 42 , 43 , 45 , 47 , 48 ]. Some studies had been performed in the State of Amazonas (22%) [ 17 , 19 , 24 , 30 , 33 , 41 , 44 , 49 ], Rondônia (14%) [ 18 , 28 , 46 , 50 , 51 ], Mato Grosso (8%) [ 21 , 31 , 32 ] and Amapá (3%) [ 20 ]. Two studies were performed using samples from populations from two different States: Pará and Rondônia (3%) [ 16 ] and Rondônia and Amazonas (3%) [ 34 ].…”

Daily mercury intake in fish-eating populations in the Brazilian Amazon

“…Despite attempts to establish reference values and background parameters as well as eliminate uncertainties about the reference dose in the Amazonian context, few studies have adopted a rigorous procedure for developing risk-based reference doses (Gaylor and Kodell, 2002;Rice, 2005). Dietary and genetic factors (Passos et al, 2003b(Passos et al, , 2004(Passos et al, , 2007aKlautau-Guimara˜es et al, 2005) as well as other specificities of the Amazonian traditional populations, make it difficult to evaluate the suitability of using current reference doses for methyl mercury exposure in the Amazon. Despite this difficulty, allegations that daily consumption of mercurycontaminated fish in large amounts poses no health hazards, based on the absence of mercury-induced clinical effects and the existence of general health problems (Do´rea, 2003(Do´rea, , 2004, do not take into consideration the importance of changes in biological functions on the population level and their usefulness for risk assessment (Bellinger, 2004;Rice, 2005).…”