Browsing by Author "Weerasekara, K.A.W.S."

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Cadmium and arsenic levels in edible fishes, Oreochromis niloticus (Nile tilapia) and Ompok bimaculatus (Pena walaya) from Padaviya reservoir of North Central Province, Sri Lanka
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Weerasekara, K.A.W.S.; Pathiratne, A.; Kithsiri, H.M.P.
Oreochromis niloticus (Nile tilapia) and Ompok bimaculatus (Pena walaya) are two edible fish species captured in the reservoirs in the North Central province. Objective of this study was to assess the cadmium and arsenic levels in muscle, liver and kidney tissues of O. niloticus and O. bimaculatus inhabiting the Padaviya reservoir to assess association of metal/metalloid levels in tissues with body weights, and total lengths of the fishes. The body weight (180-300g; 110-225g) and the total length (19.0-24.1cm; 24.0-34.0cm) of Nile Tilapia (n=30), and Pena walaya (n=30) respectively were recorded during three sampling events in 2018. The tissues were analyzed for cadmium and arsenic levels using Inductively Coupled Plasma Mass Spectrometry. Cadmium and arsenic contents of the muscle tissues were below the limit of detection (LOD) (<0.05 mg/kg wet weight) except cadmium in the muscle tissues of five Nile tilapia (0.05-0.10 mg/kg). Cadmium contents in the liver tissues of both Nile tilapia and Pena walaya, ranged from <0.05 to 0.14 mg/kg (wet weight) where cadmium levels of 67-70% of the fishes were below the LOD. Arsenic levels in liver tissues of Nile tilapia and Pena walaya were <0.05–0.10 mg/kg and <0.05–0.06 mg/kg respectively where arsenic levels in 83% of Nile tilapia and 97% of Pena walaya were below the LOD. Cadmium content in the kidney tissues of Nile tilapia and Pena walaya were <0.05-0.90 mg/kg and <0.05-0.40 mg/kg respectively where cadmium levels in 30% and 33% fishes were below the LOD. Arsenic was detected only in kidney tissues of 10% Nile tilapia (<0.050.46 mg/kg). Cadmium contents in liver tissues of Nile tilapia positively correlated (p <0.05) with the total length. No other significant associations were found between the metal/metalloid content in the tissues and the body size of the fishes. Results revealed that the cadmium and arsenic contents in the edible muscle tissues of most of these fishes were within the safe limits specified by the regulatory authorities for human consumption. Bioaccumulation pattern of cadmium in the tissues of both fishes followed the order: muscle < liver < kidney, showing greater cadmium bioaccumulative capacity in the kidney tissues. Periodic monitoring of metal/metalloid levels in edible fishes in Padaviya reservoir is recommended considering human safety. The data generated in this study can serve as baseline information for future monitoring and human health risk assessment programmes.
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.