Health assessment for mercury exposure among schoolchildren residing near a gold processing and refining plant in Apokon, Tagum, Davao del Norte, Philippines

Artisanal gold-mining activities in the Philippines have proliferated since the early 1980s. Presently, environmental and health monitoring conducted by several governmental agencies is limited to the determination of total mercury only. Previous studies undertaken focused mainly on the exposure of adults and workers to mercury during miningrprocessing operations. However, in one area in Mindanao, mined ores are brought down and processed in the lowlands where residential communities are exposed to environmental pollutants resulting from gold processingrrefining operations. The area of study is Apokon, Tagum, Davao del Norte, which has 29 gold processing and refining plants. Health complaints among schoolchildren in Apokon Elementary School were received by the Department of Health and were attributed to the mercury pollution in the environment. As part of a collaboration with the Health Department, UP-National Poisons Control and Information Service, the National Institute for Minamata Disease NIMD., Japan, provided technical assistance in the analytical determination of mercury in biological and environmental samples. Elevated mercury concentrations were noted in some of the river systems up to 15 km from the mining areas. Environmental quality monitoring showed T-Hg sediment levels ranged from 0.553 to 66.471 mgrg dry wt. while water samples from river systems exhibited mercury levels from 72.8 to 78.4 ngrml. Twenty-seven sediment samples from river systems near mining operations and seven water samples were also brought to the Institute for analysis. Fish samples collected showed levels ranging from 1.07 to 438.8 ngrg for total mercury and 0.71]377.18 ngrg for methylmercury. Methylmercury content in fish is predominant. All water and sediment samples collected from three sampling sites have elevated T-Hg level while three fish species have elevated T-Hg and methylmercury levels WHOrCDC, 1994.. Blood and hair samples from 162 schoolchildren aged 5]17 years were collected and analyzed at the NIMD for mercury analysis. Analytical procedures used in the NIMD for