DOMINGUES, I.

JONSSON, C. M.

MOURA, M. A. M.

NOGUEIRA, A. J. A.

OLIVEIRA, R.

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 10 a 12 de outubro de 2011 UNESP – Instituto de Biociências Rio Claro / SP  TOXICITY OF THE SUGAR CANE HERBICIDES AMETRYN AND HEXAZINONE IN ZEBRAFISH (Danio rerio) EARLY-LIFE STAGES   M.A.M. Moura1,2, I. Domingues2, R. Oliveira2, C.M. Jonsson3, A.J.A. Nogueira2  1Instituto Biológico, Lab. Ciência das Plantas Daninhas, Campinas, SP, Brasil 2CESAM e Departamento de Biologia, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal 3Embrapa Meio Ambiente, Jaguariúna, SP, Brasil e-mail: monica_moura@biologico.sp.gov.br  Herbicides are widely used in agriculture and are known as a diffuse source of pollution of surface water and groundwater. The impact of herbicides use on non-target organisms is little known although mutagenic and genotoxic effects in fish exposed to herbicides have already been observed. Sugarcane is the predominant crop of the state of São Paulo, Brazil, with an area comprising approximately five million hectares. In the present study, the toxicity of ametryn and hexazinone, two herbicides widely used in sugarcane cultivation, was evaluated using the Fish Embryo toxicity Test (FET), with Danio rerio, a tropical cyprinid used in toxicological research. The endpoints monitored included pigmentation, otolith formation, yolk absorption, pericardial oedema, tail deformation, hatching, coagulation and death. Five concentrations of ametryn (ranging from 10 to 80 mg L-1) and six from hexazinone (ranging from 0.06 to 1.0 g L-1) were tested. At concentrations over 10 mg L-1 of ametryn exposed embryos presented a general development delay, pericardial oedemas, tail deformities and a delay in yolk absorption. At concentrations over 0.06 g L-1 of hexazinone exposed embryos presented tail deformities and a delay in body pigmentation; over 0.185 g L-1 we observed pericardial oedemas and, over 0.570 g L-1 a delay in yolk absorption. In general, fish exposed to concentrations over 0.325 g L-1 presented a general development delay. Despite the low acute toxicity of ametryn and hexazinone (LC50-96 h = 52.94 (± 5.70) mg L-1 and LC50-96 h = 0.94 (± 0.07) g L-1, respectively) observed for zebrafish early-life stages, deleterious effects at sublethal level could be observed. The endpoints used on this study allow a better understanding of the toxicity and mode of action of these two herbicides, suggesting that, chronic effects due to long term exposure to the herbicides can be very important, leading to significant alterations in the organisms that might disrupt the functioning of aquatic ecosystems. Thus, as these chemicals are widely used in the field, an evaluation of risk should be performed based on the monitoring of sublethal parameters in organisms belonging to several trophic levels.   Keywords: Fish embryo toxicity test, developmental abnormalities, acute toxicity  Apoio: FAPESP (Bolsa Novas Fronteiras Proc. 2010/07118-9) e CESAM/Departamento de Biologia, Universidade de Aveiro, Portugal.  58

Toxicity of the sugar cane herbicides ametryn and hexazinone in zebrafish (Danio rerio) early-life stages.

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