Mercury (Hg) is considered one of the most dangerous toxic metals to the environment and to humans. High Hg levels may induce different types of toxic effects on human health, and the main target is the central nervous system (CNS). One of the main mechanisms involved in neurotoxicity caused by Hg is the oxidative stress and its effect on antioxidant systems. In the Amazon, Hg exposure is primarily due to the intake of fish contaminated with methylmercury (MeHg), and this exposure can be evaluated by the Hg level quantification in blood. It is currently known that deforestation is one of the main reasons for the high levels of Hg in the aquatic ecosystems in the Amazon. However, to the best of our knowledge, there are no recent investigations that evaluate the Hg exposure in a human population of the Lower Amazon region. Therefore, this study aimed to characterize the epidemiological profile of 144 residents of the Santarém municipality, and to investigate
the interaction between GSTM1 GSTT1 and GSTP1 (rs1695A>G and rs1138272 C>T) polymorphisms and blood Hg in this population. Higher Hg level was found in individuals with frequently fish intake habits (mean = 25 ± 23.9 μg/L; median = 20.5 μg/L; minimum = 3.7 μg/L; maximum = 181.3 μg/L), of which 68.8% reached Hg levels varying between 10-50μg/L. In addition was also observed that Hg levels increase with age (rs = 0.40; p = 0.0000) and that men had Hg levels higher than women (2 = 17.45; p = 0.0001). The linear regression analysis of our data suggests that fish intake ( = 14.69; p = <0.001), sex ( = 11.55; p = 0.001), GSTM1 deletion ( = 6.42; p = 0.06) and age ( = 0.26; p = 0.04) are more relevant for prediction of Hg level in blood than the polymorphisms of GSTT1 and GSTP1 genes. In this context, it was concluded that the Santarém population is exposed to Hg through to frequently fish intake habit and factors like sex, age and GSTM1 polymorphism are contributing with the high Hg levels found in the blood of analyzed individuals.
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