RESUMEN
Determination of genotoxic effect in fish, micronucleus test as well as the study of the abnormal shape of nuclei is a suitable measure, in which the presence or absence of genotoxins can be detected in water. In the present study, micronuclei and abnormal nuclei frequencies were scored in the gill and kidney erythrocytes of the fish Labeo bata grown in the sewage-fed fish farms of East Calcutta wetlands. Three experimental sites were chosen, namely, Bantala, Chowbaga and Chingrihata (basically these sites have sewage-fed fishponds), which were compared with fishponds of no sewage influence as the control area. Highly significant differences (P<0.001) were noticed for micronucleus frequencies in the gill and kidney erythrocytes of experimental fishes, where kidney erythrocytes showed an increased value than gill erythrocytes without any statistical differences. The frequencies of nuclear abnormalities such as necrotic cells, apoptotic cells, notch nucleated cells and binucleated cells were also counted separately for gill and kidney erythrocytes, in which significantly (P<0.001, P<0.01, P<0.05) increased values were obtained in comparison to control populations. These genotoxicity results confirmed that the sewage-fed ponds contain genotoxic metals such as Cr, Zn, Cu, Pb, Mn, Fe through wastewater and sludge because of the direct use of sewage water without pretreatment which may lead to health risks among humans through chronic consumption of fish from these experimental fish ponds. Other vertebrates grown in sewage-fed ponds may also suffer a certain amount of genotoxic substances.
Asunto(s)
Carcinógenos Ambientales/toxicidad , Cyprinidae/metabolismo , Eritrocitos/efectos de los fármacos , Metales Pesados/toxicidad , Aguas del Alcantarillado , Contaminantes Químicos del Agua/toxicidad , Animales , Bioensayo , Núcleo Celular/efectos de los fármacos , Núcleo Celular/ultraestructura , Cyprinidae/sangre , Monitoreo del Ambiente/métodos , Eritrocitos/química , Eritrocitos/ultraestructura , Explotaciones Pesqueras , Branquias/efectos de los fármacos , India , Riñón/efectos de los fármacos , Metales Pesados/metabolismo , Micronúcleos con Defecto Cromosómico/inducido químicamente , Pruebas de Micronúcleos , Pruebas de ToxicidadRESUMEN
Several reports have indicated that the sewage-fed vegetables of the Dhapa area, near the city of Calcutta, contain a very high amount of heavy metals. Currently 800 ha of land is being utilised throughout the year to cultivate more than eight types of vegetables, with a production of about 147 tonnes per day. A major population of Calcutta consumes these vegetables grown in the Dhapa area. Recently there has been huge pressure on the State Government to ban vegetables grown in the Dhapa area for human consumption. For this reason, we have studied the genotoxic effects of some of the most commonly used vegetable extracts from the Dhapa area after in vivo acute exposure in mice as measured by chromosomal aberrations (CA) and sister chromatid exchanges (SCE) to find out the minimum threshold dose to induce CA and SCE. Three different concentrations of the three most commonly used vegetable extracts (cauliflower, spinach, radish) were fed by gavage to mice for the study of CA and SCE. A significant increase in CA was observed only at the highest concentration of all the vegetable extract-treated groups when compared with the solvent control. A significant increase in SCE were observed in the middle and high doses of spinach and only the high dose of cauliflower and radish extract-treated series when compared with distilled water control. The lowest dose was equivalent to approximately 1 kg of vegetables consumed by a human (60 kg body weight) in a day. The middle and high doses of each vegetable extract were much higher than the normal amount of vegetables that a human can consume per day. So the minimum dose for inducing SCE and CA was much higher than the amount a human can consume in a day. Therefore this study indicates that these vegetables are safe for human consumption up to a certain limit, and attention should be given to reducing the heavy metal contents in the soil and sewage of the Dhapa area to thus reduce the heavy metal concentrations in the vegetables.