Assessing mercury contamiantion in the Amazon


Anthropogenic activities, such as gold mining and soil erosion, seem to play an important role in the recent enrichment of mercury to aquatic sediments of the Amazon. Soil erosion may have a more regional effect, while the effects of gold mining are more local.
Interestingly, the hydrographic basin of the Amazon has a very high methylating capacity for mercury, where floating macrophyte mats play an important role in the methylation of inorganic mercury to methylmercury.
Riverine humans in the Amazon are exposed to methylmercury through the ingestion of contaminated fish. Hair mercury levels in riverine human populations are commonly above 10 µg/g, which is the threshold limit for adverse neurological effects to the fetus. Recent studies in the Amazon have shown relations between adverse neurological performance and methylmercury.
Finally, predicted hair mercury concentrations in riverside human populations were compared to observed values. The results indicate that human exposure and health risks, associated with fish ingestion, may be assessed by a predictive model.

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