|Basic Concepts in Environment, Agriculture and Natural Resources Management: An Information Kit (IIRR, 1993, 151 p.)|
Toxic and hazardous wastes
TOXIC AND HAZARDOUS WASTES
Human activities produce wastes. These wastes accumulate in amounts that may harm the environment and, at sufficiently high concentration, have undesirable effects on plants, animals and man. For example, mining processes contribute heavy metals which may be leached from exposed ores and. waste rocks such as iron, copper, mercury and lead. Factories which change raw materials to finished products produce large amounts of waste products. Industrial operations emit air pollutants like carbon monoxide, oxides of nitrogen, hydrocarbon and lead.
Damage to human health
Examples of toxic wastes affecting human health are numerous:
· Recently, just as the tong-term effects of mercury poisoning in Davao del Norte are being known, disturbing reports indicate that mercury poisoning is spreading to other parts of gold-rush Mindanao.
· In Metro Manila, a World Health Organization (WHO) study revealed that Metro Manilans are exposed to at least 10 times more lead in the air than WHO-prescribed standards. Lead mainly affects the central nervous system, causing fatigue, headache, tremors and convulsion.
· The Department of Agriculture warned residents of Monkayo, Davao del Norte, against eating the meat of animals suspected to have died after drinking from polluted bodies of water. Petrochemical analysis from the Bureau of Mines reported heavy traces of cyanide in water samples.
So little is known about the health effects of hazardous wastes that setting exposure levels, in efforts to protect human health, often proves ineffective. Substances coming from wastes vary in their toxicities and produce different toxic effects. This is because they differ in the kinds of chemical reaction they undergo within the biochemical systems. For example, metallic mercury (Hg) is not poisonous. Ingestion of small amounts of mercury, as from a bit of silver amalgam a dentist uses to fill a cavity, is not considered a hazard. But, while metallic mercury is not toxic, its vapors are. Inhalation of enough mercury over a period of time affects the central nervous system, producing symptoms of insanity.
Hazardous Waste Management
Sound management of hazardous wastes is a goal not yet achieved in many countries, even developed ones. Many of the recommended/common ways of waste disposal have been proven to be ineffective and some even pose further hazards. For example, the sanitary landfill has been generally adopted as a substitute for open dumping and burning. Yet, it has been found that, in a sanitary landfill, there is a danger that explosive methane gas and toxic hydrogen sulfide gas, produced by anaerobic decomposition, can build up and explode.
Lack of Data
The lack of data on hazardous waste generation and its effects on health and environment continues to be a major stumbling block, thus hampering proper regulation.
Toxic and dangerous substances and materials that require priority consideration
Arsenic and compounds
Mercury and compounds
Cadmium and compounds
Thailium and compounds
Beryllium and compounds
Lead and compounds
Antimony and compounds
Organohalogenated compounds, excluding inert polymeric materials
Biocides and phytopharmaceutical substances
Tarry materials from refining and tar residues from distilling
Peroxides, chlorates, perchlorates and azides
Chemical laboratory materials
Selenium and compounds
Tellerium and compounds
Polycyclic aromatic hydrocarbons
Soluble copper compounds
Acids and/or basic substances used in the surface treatment and finishing of metals