Estudos de toxicidade e acumulo de endosulfan nos peixes Brachydanio rerio e Hyphessobrycon bifasciatus

AUTOR(ES)

Claudio Martin Jonsson

DATA DE PUBLICAÇÃO

1991

RESUMO

Endosulfan effectiveness in the control of insects and acarus points the need of evaluating its adverse effects on other forms of life, including aquatic organisms. In the present work, experiments were conducted with "zebra fish” (Brachydanio rerio) and "larabari or yellow-tetra" (Hyphessobrycon bifasciatus) to study endosulfan toxic effects and its toxicokinetics behaviour. In the acute toxicity experiments, endosulfan concentration in water ranged from 0 to 6.3 μg/l, and the LC50-24h values were 2.6 (2.3 – 2.9) and 1.6 (1.3 - 2.1) μg/l for H. bifasciatus and B. reriu, respectively. Behaviour changes including hyperactivity, erratic swimming and convulsions were observed at these exposure levels. In the bioaccumulation studies, wich were extended for 21 days, the pesticide mean concentration in water was 0.3 μg/l, and the levels of endosulfail residues at the end of the exposure were 0.808 +/- 0.116 and 1.703 +/- 0.072 μg/g b.w. in S. rerio and H. bifasciatus, respectivelly. The estimated values of bioconcentration factor (BCF) in H. bifascistus and B. rerio were 11,583 +/- 2,361 and 2,650 +/- 441, the total endosulfan residues being in both species eliminated with biological half-lives (t 1/2b) lower than 5 days. Histopathological studies showed predominant acute effects in the gills with inflammatory infiltration, necrosis and separation of respiratory gill epitelium. In the liver, typical damages related to subacute effects were observed, evidencing lipidic degeneration and nuclear alterations in the hepatocites. The results indicate that endosulfan is highly toxic to the fish B. rerio and H. bifasciatus, and that despite its low stability in water; this pesticide accumulates in body tissues after continuous exposure. Additional long-term toxicological studies seems to be necessary since some histological evidences suggest a possible evolution to neoplasms.

ASSUNTO(S)

peixe - controle biologico

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