Browsing by Author "Waduge, V.A."

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Background radiation levels near a mineral sand mining factory in Sri Lanka: Correlation of radiation measurements with micronuclei frequency
(Nuclear Technology Pub, 2020) Warnakulasuriya, T.; Williams, S.; Weerakkody, T.; Dabarera, M.; Rodrigo, K.; Waduge, V.A.; Ediriweera, D.; Siriwardena, N.; Wickremasinghe, R.
ABSTRACT:Lanka Mineral Sands Ltd (LMS) is a company operating in Pulmoddai, Sri Lanka, mining for rare earth minerals along with monazite which contains thorium that emits ionizing gamma and alpha radiation on decay. The objective of the study was to determine the background radiation levels and selected radionuclides and then to correlate these levels with the frequency of micronuclei (MN) among persons residing in the vicinity of LMS. A cross-sectional study was conducted among persons of both sexes between 35 and 45 years of age residing in the vicinity of LMS. Background radiation measurements were obtained by a survey metre, and gamma spectrometry was done on soil samples. Five millilitres of venous blood was drawn for cytokinesis-blocked MN assay. Background radiation levels measured by the survey metre; 232Th, 226Ra and 210Pb mass activities in soil were highest in the samples collected from the LMS. The background radiation measurements positively correlated with MN frequency although the magnitude of the correlation was small (r = 0.176, p = 0.04). This implies that chronic long-term exposure to low-dose radiation may result in genotoxicity. Prospective large-scale studies are recommended to evaluate the long-term effect of exposure to low-dose radiation at Pulmoddai.
Preliminary study on identification of region of production of Ceylon Tea using concentration of selected elements
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) de Silva, N.I.U.; Madhusha, R.K.D.; Waduge, V.A.; Mewan, K.M.; Amarakoon, A.M.T.
Sri Lanka is one of the world's leading tea exporters and Ceylon Tea is acclaimed as the best tea in the world due to its unique flavor characteristics. Flavor characteristics of tea are mainly influenced by the variety of tea, climatic conditions and processing methods. Tea is grown in several geographical regions in Sri Lanka and tea produced in those regions acquire distinct flavor characteristics specific to the region. Due to the distinct flavor characteristics, Ceylon Tea fetches higher prices in the international markets than tea produced in other countries. Often Ceylon Tea is blended with tea from other origins and sold as Pure Ceylon Tea to obtain higher prices. In addition, tea produced in particular regions in Sri Lanka are blended with tea produced in other regions of Sri Lanka (e.g. Dimbulla and Uva) which are much sought after teas of Sri Lankan origin. At present, organoleptic assessments are used to identify such adulterations, which could be challenged in courts and arbitration panels. Although not essential, identification of chemical parameters specific to the region of production would facilitate obtaining geographical indications (GI) for tea produced in certain regions such as Dimbulla and Uva in Sri Lanka. Therefore, chemical parameters to distinguish Ceylon Tea from other origin teas and to identify the region of production in Sri Lanka would be invaluable for the marketing of Ceylon Tea. A combination of trace metal content and isotopic ratios of Nitrogen (N), Carbon (C) and oxygen (O) are often used to identify the geographical region of production. Therefore, content of selected metals in tea produced in five regions (Low country, Mid country, Udapussellewa, Up country and Uva) of Sri Lanka was measured as a preliminary investigation to find any relationship with the region of production. Potassium, calcium, manganese, iron, copper, zinc, rubidium, strontium and bromine content of fifteen tea samples representing the five regions were measured using Xray Fluorescence Spectroscopy (XRF) technique. The results obtained, in the present study indicated that there is a direct correlation between the rubidium content of tea and the region of production. Mean Rb content of tea in the five production regions (mg kg-1) were 45.43 (Low country), 39.31 (Mid country), 36.89 (Udapussellewa), 30.98 (Up country) and 20.29 (Uva) on dry weight basis. Tea produced in lower elevations had high Rb content and the Rb content of tea decreased with the increase in elevation. The differences of Rb content in tea could be due to the differences in Rb content in soils in these regions. Results obtained for concentrations of other elements did not indicate any relationship with the region of production. Results of this study indicate that Rb content could be used as one of the parameters for the identification of region of production in Ceylon Tea. Further studies using larger number of tea samples from each region along with soil samples from those regions is required for confirmation of the conclusion.
Quest to identify geochemical risk factors associated with chronic kidney disease of unknown etiology (CKDu) in an endemic region of Sri Lanka-a multimedia laboratory analysis of biological, food, and environmental samples
(Springer, 2016) Levine, K.E.; Redmon, J.H.; Elledge, M.F.; Wanigasuriya, K.P.; Smith, K.; Munoz, B.; Waduge, V.A.; Periris-John, R.J.; Sathiakumar, N.; Harrington, J.M.; Womack, D.S.; Wickremasinghe, R.
The emergence of a new form of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka's North Central Province (NCP) has become a catastrophic health crisis. CKDu is characterized as slowly progressing, irreversible, and asymptomatic until late stages and, importantly, not attributed to diabetes, hypertension, or other known risk factors. It is postulated that the etiology of CKDu is multifactorial, involving genetic predisposition, nutritional and dehydration status, exposure to one or more environmental nephrotoxins, and lifestyle factors. The objective of this limited geochemical laboratory analysis was to determine the concentration of a suite of heavy metals and trace element nutrients in biological samples (human whole blood and hair) and environmental samples (drinking water, rice, soil, and freshwater fish) collected from two towns within the endemic NCP region in 2012 and 2013. This broad panel, metallomics/mineralomics approach was used to shed light on potential geochemical risk factors associated with CKDu. Based on prior literature documentation of potential nephrotoxins that may play a role in the genesis and progression of CKDu, heavy metals and fluoride were selected for analysis. The geochemical concentrations in biological and environmental media areas were quantified. Basic statistical measurements were subsequently used to compare media against applicable benchmark values, such as US soil screening levels. Cadmium, lead, and mercury were detected at concentrations exceeding US reference values in many of the biological samples, suggesting that study participants are subjected to chronic, low-level exposure to these elements. Within the limited number of environmental media samples, arsenic was determined to exceed initial risk screening and background concentration values in soil, while data collected from drinking water samples reflected the unique hydrogeochemistry of the region, including the prevalence of hard or very hard water, and fluoride, iron, manganese, sodium, and lead exceeding applicable drinking water standards in some instances. Current literature suggests that the etiology of CKDu is likely multifactorial, with no single biological or hydrogeochemical parameter directly related to disease genesis and progression. This preliminary screening identified that specific constituents may be present above levels of concern, but does not compare results against specific kidney toxicity values or cumulative risk related to a multifactorial disease process. The data collected from this limited investigation are intended to be used in the subsequent study design of a comprehensive and multifactorial etiological study of CKDu risk factors that includes sample collection, individual surveys, and laboratory analyses to more fully evaluate the potential environmental, behavioral, genetic, and lifestyle risk factors associated with CKDu.
Stable isotopic characterization and baseline monitoring on mangrove ecosystem in Negombo lagoon using carbon and nitrogen stable isotopes
(Faculty of Graduate Studies, University of Kelaniya, 2015) Handagiripathira, H.M.N.L.; Deeyamulla, M.P.; Rogers, K.; Waduge, V.A.
The stable isotope ratios of 13C/12C and 15N/14N and the weight ratio of total carbon to total nitrogen (C:N) are important indicators in the field of environmental monitoring. As a part of the assessment of nutrient enrichment in Negombo lagoon ecosystem, stable isotope technique is used to study the stable isotope ratios of mangroves and adjacent water. Although this technique is an advanced tool to identify the fingerprints of environmental pollutant sources, totally newel to the research field in Sri Lanka. The fresh mangrove leaves (young, matured and old) of Rhizophora apiculata and Rhizophora mucronata spices, totally 35 samples and 10 surface water samples were collected from 12 sampling points randomly selected from the bank of Negombo lagoon. The leaves were rinsed with distilled water, oven dried at 40 0C for 48 hours and powdered. The water samples were filtered into glass fiber filters to collect suspended particulate materials in the water and filter papers were oven dried at 40 0C for 24 hours. Samples were analyzed by combustion on a Eurovector elemental analyzer coupled to an Isoprime mass spectrometer in GNS science, New Zealand. There were some effects of %Nitrogen (%N) on the old leaves where the %N is quite low (range 0.3% to 1.7% with a mean value of 0.6%), but generally young and matured leaves had similar trend in % N (range 1.1% to 2.9% with a mean value of 1.8% and range 0.7% to 2.9% with a mean value of 1.5% respectively). The behavior of isotopic Nitrogen-15 ratio (15N) in those three types of mangrove leaves was significantly divers compared with behavior of %N in leaves. The range of 15N in young and matured leaves was from 2.3‰ to 12.3‰ with a mean value of 5.4‰ and this ratio in old leaves had a range from 5.1‰ to 8.0‰ with higher average of 6.52‰. The average % Carbon values (%C) of all the three types of mangrove leaves were in the range of 42% to 43%. The isotopic Carbon-13 ratio (13C) of young, matured and old leaves was within the common range for C3 plants, with values ranging from -25.4 to -32.7‰ and average of -29.5‰. The total Carbon to total Nitrogen ration (C: N, atom) had increased in older leaves (range 36.2 to 163.3 with mean value of 120.8), and significantly decreased in matured and young leaves (average values of 41.9 and 34.5 respectively). The average 13C value of the lagoon water was -24.6‰ and average 15N value of the water was 6.7‰. The carbon and nitrogen isotopic compositions obtained in this study are comparable with previously published results in the other coastal regions of the world. As an initiative research study on the stable isotope analysis in Sri Lanka, the results and findings, generated in this study can be considered as the baseline data for future studies based on the lagoon ecosystem.