International Postgraduate Research Conference (IPRC)
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Item Combination of Physico-Chemical Analysis and A Plant Bioassay for Screening Potential Toxicity of Drinking Waters in Selected Dug Wells in Medawachchiya Area, Sri Lanka: A Preliminary Study(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Weerasekara, K.A.W.S.; Pathiratne, A.; Kithsiri, H.M.P.Chronic Kidney Disease of unknown aetiology (CKDu) is becoming a major health problem especially in the North Central Province of Sri Lanka showing the highest prevalence in Medawachchiya area. Aetiology of this disease seems to be multifactorial which includes chronic exposure to environmental toxicants. This study reports the preliminary results of an ongoing study which has mainly focused on evaluating potential toxicity of drinking water in the dug wells in the Medawachchiya area using combination of physico-chemical analysis and bioassays.Eight dug wells were selected for the study using judgmental sampling method which included four drinking water sources of CKDu affected families and four wells which have been used by the families with no clinical signs of CKDu (Reference wells). Water samples obtained from these wells during prolong dry season in August 2016 were analyzed for physico-chemical parameters and the herbicide glyphosate using standard analytical methods.Potential toxicity of water samples was examined by the bioassay with the plant model (Allium cepa) following standard protocols with aged tap water and mineral water as negative controls. Results revealed that total hardness of the water of dug wells used by CKDu affected families were above the standard limits (250 mg/L, SLSI:2013). Alkalinity levels of water of all the wells used by the CKDu affected families and one reference dug well also exceed the stipulated limits for drinking water (200 mg/L, SLSI:2013). Arsenic was detected (2.0 μg/L) in water of one dug well used by CKDu affected families. Glyphosate was not detected in all drinking water samples (< 5 μg/L, detection limit). The bioassay indicated potential toxicity associated with water in the dug wells used by CKDu affected families based on A. cepa root growth retardations effect compared to negative controls and reference dug wells (P < 0.05). Further studies will be continued using bioassays with plant and animal models covering different climatic seasons in order to evaluate potential toxic/cytotoxic/genotoxic effects associated with the drinking waters of the dug wells used by CKDu affected families.Item Assessing Potential Genotoxic Effects of Nano-Titanium Dioxide on Nile Tilapia (Oreochromis Niloticus)(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) de Silva, P.; Pathiratne, A.Due to widespread use of titanium dioxide nanoparticles (nano-TiO2) in many industrial applications, significant release of nano-TiO2 to the environment can occur which may eventually reach aquatic ecosystems. Hence biological impacts of nano-TiO2 to the aquatic fauna especially fish under chronic exposure need to be explored. Nile tilapia, Oreochromis niloticus is used as a bioindicator for evaluating toxic effects to environmental substances in tropical waters. The aim of the present study was to assess the potential genotoxic effects of water-borne nano-TiO2 on Nile tilapia under chronic exposure conditions. Fish were exposed to a range of nano-TiO2 (<25 nm, anatase) concentrations viz 0.1 mg/L, 0.5 mg/L and 1.0 mg/L along with the controls for 21 days and genotoxic effects were evaluated weekly by micronucleus assay and Comet assay using peripheral erythrocytes. Even though micronuclei induction in the erythrocytes was higher in the fish exposed to the lowest nano-TiO2 concentration (0.1 mg/L) at 7 and 21 days of exposure, a statistically significant concentrationresponse pattern was not observed (P > 0.05). Comet assay revealed that DNA damage in erythrocytes of Nile tilapia could be induced by nano-TiO2 even at 0.1 mg/L level (P < 0.05) by 21 days of exposure. Compared to micronucleus assay, Comet assay was more effective in detecting genotoxic effects on Nile tilapia. The results indicate that nano-TiO2 exposure could lead to genotoxic hazards to the fish populations in the contaminated water bodies.Item Use of erythrocytic nuclear abnormalities of feral fish species as biomarkers for assessing potential genotoxic impacts in Kelani River(Faculty of Graduate Studies, University of Kelaniya, 2015) Ruvinda, K.M.S.; Pathiratne, A.Nuclear abnormalities in the peripheral erythrocytes of fishes inhabiting contaminant waters are useful biomarkers for assessing genotoxic potential of surface waters impacted by anthropogenic contaminants. Kelani river which receives a wide variety of contaminants from multiple sources including industrial effluents and domestic waste, is ranked as the most polluted river in Sri Lanka. However, scientifically based evidences on biological impacts of Kelani river pollution on its resident fauna are meagre. In the present study, frequencies of erythrocytic nuclear abnormalities in the two fish species inhabiting Kelani river viz. Etroplus suratensis and Dawkinsia singhala were evaluated in order to assess the potential genotoxic impacts. E. suratensis were sampled from Ruwanwella (upstream) and Mattakkuliya (seaward site) sites, whereas D. singhala were sampled from the sites located in Ruwanwella and Kaduwela (between upstream and seaward site) during the years 2013-2015 covering dry and wet periods. Erythrocytic nuclear abnormalities in the blood of sampled fishes were evaluated using standard procedures. In addition, surface waters of the fish sampling sites were physico-chemically characterized using standard analytical procedures. Water quality parameters indicated high levels of chemical oxygen demand and heavy metal levels in Mattakkuliya and Kaduwela sites in comparison to Ruwanwella site. Despite temporal variations, frequencies of total erythrocytic nuclear abnormalities were significantly higher in the E. suratensis sampled from Mattakkuliya site than those from Ruwanwella site (P <0.05). In addition, D. singhala sampled from Kaduwela site had significant total erythrocytic nuclear abnormalities than the fish from Ruwanwella site. Of the four types of nuclear abnormalities detected, blebbed and noched nuclei contributed mainly to the induction of total erythrocytic nuclear abnormalities than binuclei and nuclear buds. Comparison of erythrocytic nuclear abnormalities of the two feral fish species inhabiting Kelani river together with physico-chemical analysis revealed that Mattakkuliya and Kaduwela sites of the Kelani river are polluted with genotoxic contaminations which can induce harmful impacts on indigenous fauna. This study was funded by the National Research Council research grant 11-11 and National Science Foundation equipment grant RG/2011/EQ/16.Item Assessing toxicity of selected textile industry effluents reaching Kelani River using a plant based bioassay(Faculty of Graduate Studies, University of Kelaniya, 2015) Hemachandra, C.K.; Pathiratne, A.Textile industry effluents that are discharged in high volumes into inland waters may contain complex mixtures of toxic substances that could pose health impacts to biota inhabiting receiving waters. Conventional effluent quality assessments such as physico-chemical characterization may not be adequate to evaluate their biological effects. In the present study, potential toxicity of selected textile industry effluents discharged into Kelani River were assessed by a plant based bioassay using Allium cepa (onion) as the test organism. Effluents were collected from the discharging points of two textile industries in three sampling occasions covering mostly dry periods. Onion bulbs were exposed to the effluents under undiluted and diluted (1:8) conditions using aged tap water as the dilution media. Toxicity endpoints were root growth, mitotic index, occurrence of chromosomal aberrations and nuclear abnormalities. A. cepa root tip cells exposed to undiluted effluents from both industries caused significant (p<0.05) root growth inhibition, mitotic depression compared to that of the controls along with a significant (p<0.05) induction in the occurrence of condensed nuclei at each sampling occasion indicating cytotoxic effects. Moreover, undiluted effluents significantly (p<0.05) induced chromosomal abnormalities with further induction in micronuclei in the root tip cells indicating genotoxicity. Exposure of onion bulbs to the 1:8 diluted effluents also showed significant alterations of toxicity end points depending on the effluent type and sampling occasion. The results revealed that 1:8 dilution was not adequate to eliminate the cytotoxicity/genotoxicity induced by the effluents completely. Physicochemical characterization of the effluents showed that heavy metal levels generally comply with the national tolerance limits for effluent discharge into surface waters. However, color measurements and chemical oxygen demand levels did not comply with the tolerance limits in most of the cases indicating that highly oxidizable organics including textile dyes might have contributed to the observed toxicity. Present study showed the necessity of incorporating bioassays into effluent monitoring programs for more realistic effluent quality assessments, considering ecosystem and public health. This study was funded by the National Research Council research grant 11-11 and National Science Foundation equipment grant RG/2011/EQ/16.