Many hazardous waste sites are located in environmentally sensitive areas,
such as floodplains or wetlands. When the sites became full or were abandoned,
they frequently were left uncovered. The locations for these sites were selected
more for convenience and expedience than environmental concern.
Acute toxicity is a serious effect, such as a burn, illness, or death, that
occurs shortly after exposure to a hazardous substance. Chronic toxicity
is a serious effect, such as an illness of death, that occurs after prolonged
exposure to small doses of a toxic substance.
Regulating hazardous substances is difficult because they affect the air,
water, and soil and some can be hazardous in extremely low concentrations.
In addition, definitions of hazardous and toxic wastes differ among countries,
as do the concentrations of those wastes that are considered hazardous to
human health.
Hazardous wastes pollute the air, water, or soil simply by the way they
are stored or contained.
Industrial landfills, surface impoundments, and special facilities are all
used to dispose of hazardous wastes. The toxins in such sites can leach into
the soil and cause groundwater contamination.
The problem of linking a particular chemical or other hazardous waste to
specific injuries or diseases is complicated by the lack of toxicity data
on most hazardous substances. There is disagreement on how much of a hazardous
substance may be harmful.
The National Priority List is a listing of hazardous-waste dumpsites in
the United States that require urgent attention under the Superfund Program.
Five technologies for managing wastes are thermal treatment, or incineration;
neutralization, which mixes the toxins with a neutral element; immobilization,
which converts it to a solid form; waste separation, which separates components
of the waste; and air stripping, which removes volatile chemicals from the
waste.
Pollution prevention is the process of preventing, entirely or partially,
the pollution that would otherwise result from some production or consumption
activity. Waste minimization is a process that reduces the amount of waste
produced.
The first step in the pollution prevention hierarchy is to reduce the amount
of pollution at the source. Second is to recycle wastes wherever possible.
Third is to treat wastes to reduce their hazard or volume. Fourth is to dispose
of the waste on land or incinerate the waste as a last resort.
RCRA is the Resource Conservation and Recovery Act. It defines hazardous
and toxic materials and regulates their production. CERCLA is the Comprehensive
Environmental Response, Compensation, and Liability Act (Superfund). It is
the 1980 law that addressed the issue of cleanup of hazardous-waste sites.
