PARENT SESSION
PM15 - Field Studies: Causal Relationships Between Exposure & Effect
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P360) Bioassessment of Ecological Risk of Amazonian Itchyofauna Associated to Hg Exposure.
Castilhos, Zuleica Carmen*,1, Almosny, Nadia2, Souto, Paulo Sérgio3, Bidone, Edison Dausacker2, Pereira da Silva, Luis Carlos2, 1 CETEM- Center for Mineral Technology, Rio de Janeiro, Rio de Janeiro, Brazil2 Federal Fluminense University, Niterói, Rio de Janeiro, Brazil3 Agriculture College of Pará State, Belém, Pará, Brazil
ABSTRACT- In Amazon artisan gold mining, mercury (Hg) is released to environment during its use to amalgamate the fine particles of gold. Once mercury entries in aquatic ecosystems, it might be methylated to methylmercury (MeHg). The transference factors of MeHg through the food chain involving Amazonian fish suggested that biomagnification may occur in both the contaminated and background areas. Whereas potential human health effects from Hg exposure have received considerable attention, there are no studies with wild fish collected from Amazonian contaminated sites to explore adverse effects in fish of realistic environmental Hg concentration. It has been demonstrated that MeHg has affinity for red blood cells in some species, but there are few data about its hematological effects in freshwater fish. The kidneys are excretory and the primary organ of leukopoiesis and hematopoiesis in fish. Thus, hematological chances also should be affect the imunological parameters. Besides the Amazonian fish hematological reference values are scarce. The top predator Tucunare may be considered good indicator of Hg accumulation in the Amazonian ecosystem, specially because its time integration capacity, sedentary and territorial behavior, and slow moving water preference. The objectives of this work were to establish and compare the hematological parameters (erythrocites, hematocrit, leucocytes and mean corpuscular volume) and to investigate their relationship for Hg accumulation by Tucunare from contaminated and background areas. Close to 50 Tucunares were caught at each of two sites in the Tapajos River region, and the fish sampling was oriented by DRAC (Dose-Resposta para Avaliacao da Contaminacao) methodology rather than the opportunity. Both the level of Hg tissue and hematological responses were measured in each specimen and the relationship among data were investigated. The results showed significant differences in hematological parameters and Hg concentration considering contaminated and background areas. One could suggest that those hematological parameters might be used as physiological biomarkers of Hg exposure in ecological risk assessment process.
Key words: mercury, hematological effects, ecological risk, field study