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A B S T R A C TThreat posed by the heavy metals has been increasing globally rendering many water bodies unfit for human consumption. This could be due to the increase in concentrations of these metals above natural background. This article reviews the literature data on variation of water quality in rivers, lakes, and ex-mining ponds in Malaysia and other selected countries. World Health Organization (WHO), United States Environmental Protection Agency, and Malaysian water quality standards (INWQS) are used as the baseline for the pollution and health risk assessments. It illustrates that concentrations of Pb, Cd, and As in lakes and ex-mining ponds, and Mn, Cd and Pb in rivers exceed permissible limits for direct consumption. The levels of dissolved oxygen, TSS, and chemical oxygen demand (COD) are not within WHO and INWQS limits, pH of lakes and ex-mining ponds are lower than reference standards while that of rivers are high. Principal component analysis reveals that TSS, COD, BOD, Pb, and As are highly associated with ex-mining ponds. Cluster analysis shows similarity in pollution source between lake and ex-mining ponds. Risk assessment revealed that high chronic daily intake and metal index were beyond acceptable limit indicating high risk and exposure to toxic metals.

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The objective of this work is to prepare a cost-effective, low reagent consumption and high performance polytetrafluoroethylene (PTFE) vessel that is capable to work in domestic microwave for digesting food and environmental samples. The designed vessel has a relatively thicker wall compared to that of commercial vessels. In this design, eight vessels are placed in an acrylonitrile butadiene styrene (ABS) holder to keep them safe and stable. This vessel needs only 2.0 mL of HNO3 and 1.0 mL H2O2 to digest 100 mg of biological sample. The performance of this design is then evaluated with an ICP-MS instrument in the analysis of the several NIST standard reference material of milk 1849a, rice flour 1568b, spinach leave 1570a and Peach Leaves 1547 in a domestic microwave oven with inverter technology. Outstanding agreement to (SRM) values are observed by using the suggested power to time microwave program, which simulates the reflux action occurring in this closed vessel. Taking into account the high cost of commercial microwave vessels and the volume of chemicals needed for various experiments (8–10 mL), this simple vessel is cost effective and suitable for digesting food and environmental samples.