Toxic and hazardous wastes
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.
Important issues
Toxicity
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
Chromium(VI) compounds
Lead and compounds
Antimony and
compounds
Phenolic compounds
Cyanide
compounds
Isocyanates
Organohalogenated compounds, excluding inert
polymeric materials
Chlorinated solvents
Biocides and phytopharmaceutical
substances
Tarry materials from refining and tar residues from
distilling
Pharmaceutical compounds
Peroxides, chlorates, perchlorates and
azides
Ethers
Chemical laboratory materials
Asbestos
Selenium and
compounds
Tellerium and compounds
Polycyclic aromatic
hydrocarbons
Metal carbonyls
Soluble copper compounds
Acids and/or
basic substances used in the surface treatment and finishing of
metals
Organochlorines
(e.g.,PCBs,DDT)
