Chapter 12 Persistent Toxic Substances in the Philippine Environment

Abstract

Abstract This chapter provides a comprehensive review of the studies on persistent toxic substances (PTS) in the Philippines environment. Many of these persistent organic pollutants (POPs) including pesticides and industrial chemicals, which were either banned or restricted for use in most northern industrialized countries, are still in use in some developing countries. This review focuses on organochlorine compounds (OCs) such as dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs) and hexachlorobenzene (HCB) in the Philippines environment and biota. It also includes a review of residue levels of industrial chemicals such as polychlorinated biphenyls (PCBs), unintentional contaminants such as polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) and also the new candidates of POPs, polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). Environmental monitoring of POPs in the Asia-Pacific region, including the Philippines, revealed apparent POPs contamination particularly of PCBs and dioxins. Consequently, these studies suggest higher risk and exposure of the general populace to these toxic contaminants, more so for people residing near dumping site areas, where elevated concentrations of PCDD/Fs have been noted. PBDEs and HBCDs in human breast milk samples are widely present in general population of the Philippines as that of OCs. It can be presumed that PBDEs may become a major environmental concern in the Philippines as they were found at elevated levels in our work and were higher than in Japan, an industrially developed country. HBCDs were also higher than those reported in other available reports. Although decrease in POPs contamination may have been observed recently on a global scale, developing countries, such as the Philippines, may act as potential sources for certain contaminants for many more years. Therefore, a more systematic and continuous multi-media monitoring of these toxic substances in the Philippines seem imperative. Human health implications and toxic effects to wildlife must likewise be investigated.