Methylmercury human exposure has been widely studied in the Amazon. Its presence in the aquatic environments has a both natural and anthropogenic origin, exposing Amazonian riverside populations to this toxic organic form of mercury because of their intense fish consumption.This review aims to illustrate mercury human exposure in the Amazonian regions highlighting spatial distribution by basin and target group, looking for trends.The reviewed papers were selected from biomedical databases.
We included studies with a direct measure of hair mercury concentrations in a sample size bigger than 10 people, without considering the objectives, approach of the study or mercury speciation.The results are presented in thematic tables and maps, displaying hair mercury levels and specifying the target group.
Results: The highest hair mercury levels can be found in small and isolated communities from the central Amazonian regions, particularly on the Tapajos River basin. The exposure seems very heterogenic ranging from 1.1 to 34.2 ug/g.
Even if some studies found men to be more exposed than women, neither gender nor age seemed to be significantly related to hair mercury levels. Overall, authors emphasized fish consumption frequency as the main risk factor of exposure.
Some studies found an adverse effect of mercury exposure on psychomotor performance. However, it was not possible to identify a clear relation between hair mercury levels and health impact in the Amazonian situation.
Conclusions: Taking into account the low mercury levels currently handled as acceptable, the majority of the Amazonian populations can be considered exposed to mercury contamination, without clear spatial trend.
Knowing that these traditional Amerindian communities depend highly on fish, the situation is very complex and it remains difficult to assess the Public Health implication of the exposure in this specific context.
Author: Flavia BarbieriJacques Gardon
Credits/Source: International Journal of Health Geographics 2009