CAMILA FREITAS VILELA SCOPEL

Abstract:

Bisphenol A (BPA) is a diphenol used in the production of polycarbonate, a polymer commonly found in plastics and resins. The presence of BPA in plastics has been a major concern in recent years, not only because of environmental contamination, but also because of its risk to public health in relation to its mutagenic and carcinogenic potential. In this study we evaluated the toxicity of bisphenol A and determined the 50% lethal concentration (LC 50%) using zebrafish (Danio rerio) embryos as an animal model. BPA was prepared in concentrations ranging from 1 to 100 μM, diluted in 0.5% dimethylsulfoxide (DMSO) E3 medium. Negative controls included embryos exposed to E3 medium supplemented with 0.5% DMSO and positive controls embryos exposed to camptothecin (CPT), a known inhibitor of cell proliferation, diluted in 0.5% DMSO in E3 medium at a concentration of 0.001μM. The experiments were performed in triplicate according to the specifications of the Organization for Economic Cooperation and Development (OECD). One embryo / well (25 embryos per group) was distributed in 96- well microplates in the presence or absence of compound. The plates were kept in BOD incubators with controlled temperature of 28.5 ºC and photoperiod of 14h light: 10h dark. After 24h, 48h, 72h and 96h, the embryos were evaluated according to the following parameters: mortality, coagulation, heartbeat rate, hatching rate and presence of morphological abnormalities and photographs were obtained by photomicroscopy. Cell death by apoptosis was evaluated by the DNA ladder assay. The DNA was extracted by phenol: chloroform method and analyzed by 1% agarose gel electrophoresis and bands corresponding to DNA fragments were visualized after staining with ethidium bromide in a transilluminator. The LC50 determined for BPA at different exposure times was 69.94 μM at 24 hours, 72.22 μM at 48 hours, 46.63 μM at 72 hours and 31.38 μM at 96 hours. Based on our results, we can conclude that BPA has a direct toxic effect on the embryonic development of zebrafish, leading to morphophysiological changes, altering motility, hatching rate and decreasing heart rate. The results suggest that BPA acts in a time and concentration dependent manner. According to our results, we cannot confirm that apoptosis is an important pathway in the mechanism of embryo death, but we clearly demonstrate that BPA interferes with the development of various organs and tissues throughout the embryo development, causing damage that may lead to death. In  conclusion, this study showed that BPA induced marked malformation abnormalities in zebrafish embryos at the concentrations tested, demonstrating its toxicity and potential environmental impact. This suggests the need for a better assessment of BPA migration from plastic packaging to food and water used by humans.

	COMPLETE TEXT
	UFG DIGITAL LIBRARY