Neurological manifestations in riverine populations from areas exposed to mercury in the Brazilian Amazon

This study evaluated current levels of mercury exposure and sensory symptoms in adults from three riverine communities in Para State, Brazil, two of which located in the Tapajos River basin and one in the Tocantins basin. Participants in this study included 78 residents in Barreiras (Tapajos), 30 in Sao Luiz do Tapajos (Tapajos), and 49 in Furo do Maracuja (Tocantins). Total hair mercury concentrations were quantified by atomic absorption spectrophotometry, and neurological evaluation was conducted by routine examination. Mercury concentrations in the Tapajos communities were higher than those in the Tocantins (p < 0.01). Evaluation of neurological changes showed no significant difference between the communities in exposed areas and control areas for the changes observed by conventional neurological examination, except for gait deviation (p < 0.05). The study concludes that despite the mercury exposure levels, there was a low frequency of sensory alterations according to conventional neurological testing.