FISH CONTAMINATION AND HUMAN EXPOSURE TO MERCURY IN TARTARUGALZINHO RIVER, AMAPA STATE, NORTHERN AMAZON, BRAZIL - A SCREENING APPROACH

This study reports for the first time, the Hg concentrations in the fi sh fauna of the Tartarugalzinho river basin - an important gold mining region in Amapa State, Northern Amazon - and evaluates human exposure to Hg due to fish consumption in the area. We analyzed 16 fish specie s (carnivorous and omnivorous) common in the aquatic environment of th e Tartarugalzinho area and which are mostly consumed by the local popu lation. Mercury concentrations in fish ranged from 35 mu g.kg(-1) to 1 ,225 mu g.kg(-1). Among the analyzed fish, 8 species (50%) presented H g concentrations higher than 500 mu g.kg(-1), the U.S. Food and Drug A dministration (FDA) Action Level for concentration of Hg in fish. No s tatistical difference was observed between Hg mean concentrations in c arnivorous and omnivorous fish. Within a given species, Hg concentrati ons were positively correlated with fish size or weight. The Hg concen tration ratio between fish and water showed values higher than 50,000. Human exposure was estimated through the daily Hg intake obtained thr ough interviews with the local population on the amount and species of fish consumed and the Hg concentration in the fish. The estimated ave rage daily intake was 114 mu g.day(-1). This amount is approximately o ne-half of the WHO recommended provisional tolerable Hg weekly intake. At screening level, it assumes that there is a level of exposure (eg, USEPA's RfD = Reference of Dose) below which it is unlikely for even sensitive populations to experience adverse health effects. The estima ted exposure level for adult humans (1.6 mu g.kg(-1).day(-1)) was near ly 5 times greater than Hg RfD (0.3 mu g.kg(1).day(-1)). The results s uggest a widespread Hg contamination in the local fish fauna. Due to h igh fish Hg concentrations and high fish intake by local population, e nvironmental exposure to Hg is also high, presenting a health risk to population.