Introduction xxix
potential sources of disease, when these wastes accumulate and cannot be digested fairly rapidly their
disposal poses a problem. In waste-contaminated waterways the oxygen levels become depleted as a
result of bacterial activity, often to the point where fish and other aquatic organisms suffocate and die.
Many cities still have sewer lines that merge household wastes with rainwater runoff from streets
and buildings. Although the systems may be able to manage household wastes, they frequently are over-
whelmed by the combination of household sewage and runoff from a heavy rainfall. The result is that
whenever there is a storm these systems overflow and untreated sewage flows into waterways, some of
which are used for drinking water or are home to shellfish and other aquatic life. To resolve this problem,
cities are faced with the prospect of immense capital expenditures to build structures for temporarily
storing millions of gallons of runoff mixed with sewage until it can be treated. People have begun to
experiment with replacing asphalt roofs with “green” roofs and planting storm-water catchments that
make use of rainwater and thereby reduce runoff.
Today, waste management to reduce or eliminate the harmful effects of sewage release in urban and
suburban areas is required by federal law. There are, however, many rural and semi-rural parts of the
country with industrial-level animal farms that have hundreds or even thousands of animals and where
there are housing developments that use simple, unmonitored septic systems and where no or inadequate
effort is made to prevent untreated sewage from seeping into groundwater or flowing into nearby water-
ways.
As the population increases, more garbage is produced and more disposal sites are needed. Since no
one wants a dump or incinerator situated in his or her backyard, a disproportionate number of these
waste disposal sites have ended up close by the backyards of the people with the least political clout—
usually the poor and members of racial and ethnic minorities. Such obvious inequity makes social justice
a factor that must be given consideration when seeking solutions to environmental problems.
In the 1990s, many towns and cities began to reduce the amount of waste moving onto disposal
sites by recycling bottles, metal, paper and some plastics, and in recent years there have been increasing
attempts to recover valuable materials from electronic waste. Although some waste can be recycled, the
economic value of recycling fluctuates with commodity prices. Furthermore, the recovery process itself
uses energy and not all material can be reused. More and more communities are imposing recycling
regulations, encouraging residents to compost landscaping and kitchen waste, and calling for reduced
packaging. The ultimate goal is to limit landfill disposal to less than 25 percent of household waste.
TOXIC CHEMICALS AND RADIOACTIVE WASTE AND THEIR DISPOSAL
The world has always contained toxic substances, and toxic elements such as lead, cadmium and mer-
cury as well as poisonous plants and animals have always had the potential to harm living things. How-
ever, today, many industrial processes and products concentrate highly toxic materials, and their disposal
has resulted in brownfields filled with huge quantities of toxic waste.
Until the imposition of controls in the latter part of the twentieth century, the lead in leaded gasoline
and house paint and mercury from industrial processes were at concentrations high enough to induce
a variety of illnesses in humans. Numerous toxicity problems have also arisen from the synthesis of
chemicals that do not occur in nature. There are tens of thousands of synthetic chemicals and products
currently on the market for which no thorough examination of toxicity has ever been undertaken. Some
synthetic chemical compounds, unlike most natural substances are not readily biodegradable (i.e., they
deteriorate very slowly). Consequently, several man-made toxic substances such as DDT, an insecticide,