Agrochemicals - analysis, Polychlorinated Biphenyls - analysis, Ostreidae, DDT - analysis, Philippines, Water Pollutants, Chemical - analysis, Lindane - analysis, Organic Chemicals - analysis, Industrial Waste - analysis, Animals, Geologic Sediments - analysis, Herbicides - analysis, Pesticide Residues - analysis, Seasons, Chlordan - analysis, Insecticides -...