Induction of cytotoxic and genotoxic effects of Guandu River waters in the Allium cepa system

Abstract

The Guandu River is the main source of water supply for the metropolitan region of Rio de Janeiro and has been facing serious environmental problems due to increasing population and industrial pollution, as well as the presence of polluted tributaries. This study analyzed the cytotoxic and genotoxic potential of the Guandu River's waters, through the use of the Allium cepa test system. Collection points were chosen at the greatest confluences of pollutant sources. The sampling included two different seasons: the rainy season (January and February) and the dry season (June and July). The analyses of 5000 cells per treatment showed that all the points studied had some degree of cytotoxicity and/or genotoxicity. Two sampling locations, which receive major influxes from the polluted waters of the Poços/Queimados and Cabuçu/Ipiranga Rivers, stood out for the strong presence of micronuclei, sticky chromosomes, mitotic spindle abnormalities, necrotic cells and nucleolar changes compared to the negative control. At least two locations also found changes in the mitotic index. The existence of variations in the number of cytotoxic and genotoxic changes between periods of rain and drought indicates that the cytotoxic and genotoxic potential of the water pollutants varies according to time, depending on the discharges of the tributary rivers and the increase of contaminated effluents. The results highlight the importance of bio-monitoring to assist managers in the control of effluent discharge.

Evaluation of the cytotoxic and genotoxic potential of waters of the Paraíba do Sul River Basin - RJ through the Allium cepa test system

“…The roots submitted to the water samples collected in the dry season presented a higher number of cytotoxic and genotoxic alterations, indicating that the cytogenotoxic potential of the pollutants in the water varies in function of the season of the year, due to an increase in contaminated effluents. Similar results were obtained by other authors (Caritá and Marin-Morales, 2008;Oliveira et al, 2011;Gomes et al, 2015).…”

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“…One point presented statistical increase of cell proliferation and one point a greater organic load in the physicochemical analyses (Düsman et al, 2014). Gomes et al (2015) also used the. A. cepa to study the cytotoxicity of the Guandu River (Rio de Janeiro-Brazil), contaminated by urban and industrial effluents, and there were increased percentages of mitotic indexes of the onions exposed to these waters.…”

Estimación de la genotoxicidad del río Sinú mediante un bioensayo con Allium cepa l. en Montería, Córdoba-Colombia

“…En Los Garzones fueron evidentes un gran número de anomalías, indicando que este punto mostró un alto grado de genotoxicidad, debido a la acumulación de sustancias tóxicas presentes en esta zona que han venido siendo arrastradas por el caudal, las diferentes anomalías encontradas como presencia de micronúcleos (Figura 2), resultados similares a estudios reportados sobre ecosistemas acuáticos por 15 , donde las muestras presentaron micronúcleos en las aguas del río Guandú en Brasil, lo que indica la presencia de contaminantes con potencial citotóxico y genotóxico. Los micronúcleos aparecen cuando se fragmentan cromosomas durante la división de las células y son incapaces de unirse al huso mitótico, adquiriendo la forma de núcleos pequeños, por consecuencia de sustancias con efectos mutagénicos 16 .…”