International Postgraduate Research Conference (IPRC)

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    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.
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    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.