Mercury contamination caused by the amalgamation of gold in small-scale gol
d mining is an environmental problem of increasing concern, particularly in
tropical regions like the Amazon, where a new boom of such gold mining sta
rted in the 1970s. In Brazil, research into these problems has been carried
out for many years, but there is no available data for Bolivia. The presen
t paper surveys mercury contamination of a Bolivian river system in the Ama
zon drainage basin, measured in water, fish, and human hair. High concentra
tions in fish and human hair from consumers of carnivorous fish species are
reported. The potential health risk from fish consumption was evident in p
eople living downstream of gold-mining activities, but not in the mining po
pulation itself.