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Item Detection of cylindrospermopsin and microcystin-LR in well water of CKDu prevalent Medirigiriya, Sri Lanka(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Abeysiri, H.A.S.N.; Wanigasuriya, K.; Manage, P.M.Cyanobacterial blooms in aquatic systems have increased over recent decades. Many of the blooms are highly toxic, causing a serious hazard to human and animal health. The commonest cyanotoxins are hepatotoxins such as microcystin-LR (MC-LR) and cylindrospermopsin (CYN). Cyanotoxin has been proposed as one of the causative agents for CKDu in Sri Lanka and recent studies have revealed the contamination of drinking dug wells by toxin-producing cyanobacteria in the North Central, Uva and Eastern provinces. Thus, the present study was carried out to determine the contamination of CYN and MC-LR in randomly selected CKDu patients’ household well water. The study was carried out for both dry and wet seasons and water samples were collected from 42 wells in Medirigiriya and 21 wells from Hambanthota as a control area. Water temperature, pH, conductivity, Dissolved Oxygen (DO) were measured at the site itself using standard methods. N-NO3-, N-NO2-, N-NH3, total phosphorous and total hardness were measured by standard spectrophotometric and titrimetric methods. CYN and MC-LR quantification were done using ELISA detection kits (Beacon) (minimum detection limit 0.1 ppb). Identification and enumeration of cyanobacteria were carried out under a light microscope (×400). The results of the study revealed that all the tested general water quality parameters were within the Sri Lanka standards given for potable water. Mean cell densities of Microcystis sp. were varying during dry season from 60 ± 0.03 cells/mL to 307 ± 0.08 cells/mL and from 48 ± 0.07 cells/mL to 127 ± 0.73 cells/mL during wet season where MC-LR ranged from 0.02 to 6.73 µg/L and from 0.01 to 5.34 µg/L during dry and wet seasons respectively. Mean cell densities of Cylindrospermopsis sp. during dry and wet season ranged between 20 ± 0.02 cells/mL to 82 ± 0.29 cells/mL and 14 ± 0.19 cells/mL to 76 ± 0.78 cells/mL respectively, whereas the mean concentrations of CYN during dry and wet season was between 0.38 ± 0.01 µg/L to 1.45 ± 0.08 µg/L and 0.27 ± 0.04 µg/L to 1.25 ± 0.08 µg/L. Cyanotoxins and cyanobacteria were not recorded from well water collected from Hambanthota. Principal Component Analysis was done for cyanotoxin concentration, water quality parameters and a number of CKDu patients in the study area and shows a positive relationship between cyanotoxin in wells and CKDu patients who consume water from the wells (p<0.05).Item Microcystin -LR Contamination status of Nile tilapia (Oreochromis niloticus) collected from reservoirs in Polonnaruwa District, Sri Lanka.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Abeysiri, H.A.S.N.; Manage, P.M.Microcystin-LR (MC-LR) is a cyanotoxin derived from some cyanobacteria. Nile Tilapia (Oreochromis niloticus) is the most popular freshwater fish in Sri Lanka. MC-LR accumulation in Nile tilapia from four reservoirs; Parakrama Samudraya, Halmilla Wewa, Kaudulla Wewa and Ambagas Wewa in Polonnaruwa District was determined to evaluate the risk posed by the MC-LR contamination in fish on human health. Sample collection, transportation and analysis were followed according to the standard protocols and MC-LR was quantified by High Performance Liquid Chromatography (HPLC). Fish skin, flesh and head were analyzed for MC-LR and Tolerable Daily Intake (TDI) values were calculated according to the WHO guidelines (0.04 μg/day/person). The standard lengths of 30 fish ranged between 15.2 cm and 21.5 cm. The mean concentration of MC-LR in skin, flesh and head were 18.41 ± 1.76 μg/g, 0.32 ± 0.01 μg/g and 6.69 ± 0.42 μg/g respectively in fish samples collected from Parakrama Samudraya. In Kaudulla Wewa, level of MC-LR in skin, flesh and head were 13.27 ± 0.56 μg/g, 16.21 ± 0.47 μg/g and 3.08 ± 0.35 μg/g respectively and in Halmilla Wewa, MC-LR in skin and flesh were not detected. However, MC-LR in head was recorded as 0.40 ± 0.03 μg/g. In Ambagas Wewa, MC-LR levels were not detected in the fish samples. TDI of MC-LR in fish skin and head in Parakrama Samudraya was 0.35 ± 0.02 μg/day/person, and 0.16 ± 0.01 μg/day/person respectively. TDI of MC-LR in fish skin, flesh and head in Kaudulla Wewa was 0.48 ± 0.03 μg/day/person, 0.41 ± 0.04 μg/day/person and 0.07 ± 0.01 μg/day/person respectively. These values exceeded the TDI value given by WHO. However, the TDI value in fish flesh in Parakrama Samudraya was 0.007 ± 0.001 μg/day/person and the value was below the given WHO standard. Thus the present study revealed that consumption of head, and skin part of fish has a potent risk on accumulation of MC-LR in human body. Therefore, removel of head part and skin is recommended prior to consumption, in order to avoid MC-LR contamination. Further public awareness is needed to minimize the potent risk on accumulations of MC-LR in human body.