Environmental Encyclopedia
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Environmental Encyclopedia 3
Purple loosestrife
Purpole loosestrife (
Lythrum salicaria
). (Photograph
by John Dudak. Phototake. Reproduced by permission.)
hydrological regimes. Because of its attractive flowers, it has
also been planted as an ornamental species.
As a highly adaptive and tolerant plant, loosestrife
is often able to outcompete native plant species in many
environments, particularly in
wetlands
and disturbed areas.
1147
Other species often have difficulty surviving once it becomes
established, and loosestrife has low value as food and nesting
habitat
. For example, the cattail plants in many wetlands
of New York state have been replaced by purple loosestrife.
Wildlife
experts prize cattails as plants whose roots and tubes
are of high value as food source to small mammals and
rodents, and the spread of loosestrife has led to a decline in
the habitat values of these wetlands. So, in spite of its pleas-
ing appearance, New York and a number of other states
have embarked on purple loosestrife eradication programs.
The most commonly used chemical method for eradi-
cating purple loosestrife is a
herbicide
known as Rodeo--a
selective herbicide that kills only dicotyledonous or broadleaf
plants. When a diluted solution of Rodeo is sprayed directly
on mature leaves, it disrupts protein synthesis and causes
plant death within two to seven days. Physical removal of
the plants by mowing early in the growing season, prior to
seed set, has also been effective in keeping areas free of
loosestrife. See also Introduced species
[Usha Vedagiri]
R
ESOURCES
B
OOKS
Schmidt, J. C. How to Identify and Control Water Weeds and Algae. Milwau-
kee, WI: Applied Biochemists, 1987.
Thompson, D. Q. Spread, Impact and Control of Purple Loosestrife (Lythrum
salicaria) in North American Wetlands. Washington, DC: U.S. Department
of the Interior, 1987.
———. Waterfowl Management Handbook. 13.4.11, Control of Purple Loos-
estrife. Washington, DC: U. S. Fish and Wildlife Service, 1989.
PVC
see
Polyvinyl chloride
This Page Intentionally Left Blank
Q
David Quaamen (1948 – )
American writer
Nature writing is a well established tradition in American
literature, yet the label has in recent years come to be consid-
ered one-dimensional and even a little quaint by ’serious’
writers and ’real’ scientists. Many of the best nature writers
are not trained ecologists and ecology is supposed to have
out-grown natural history. Intellectuals belittle the popular-
ity of nature writing and see themselves as beyond the back-
woods genre.
Still, the American public continues to gain much of its
understanding and awareness of natural systems, of environ-
mental issues, and of humanity’s threat to wild species and
places from the best and most popular of the nature writers—
Edwin Way Teale, Annie Dillard, Terry Tempest Wil-
liams...and David Quammen. Part of the exposure comes
from the fact that many of these writers make a good part
of their living by lecturing and ’reading’ widely in popular
venues. Quammen, however, considers his writing as de-
parting “distantly from conventional nature writing, of which
I have never much cared to be either a reader or an author.”
He started writing as a novelist, but, beginning in 1981,
spent 15 years writing a column titled “Natural Acts,” for
Outside magazine, his job “to think about the natural world,
and about human relationships with that world, in a way
that would interest” the half million readers of the magazine,
an assignment which he says allowed him “unimaginable
freedom to explore a wide range of peculiar theories, remote
places, bizarre facts, and unpopular opinions.” His first
collection of essays (Natural Acts: A Sidelong View of Science
and Nature), mostly taken from his column, appeared in
1985. That collection was well received, with one reviewer
suggesting that Quammen “breathes importance into the
little-known nitty-gritty of biology” and in the process “de-
scribes wondrous places, people and situations.”
Still, Quammen does write about nature, and though
many of his essays are “very funny and very offbeat,” (the
word quirky is often used) they are just as frequently serious
1149
commentaries on science and its relationship to politics,
philosophy, and a variety of other subjects. Perhaps then,
it is more appropriate to use his own descriptor and call him
a science journalist. Lee Dembart in the Los Angeles Times
stated that “Quammen likes science for its own sake, but he
also likes it for the larger truths it suggests. He works the
fringes of science and draws conclusions that are universal.”
Marilyn McEntyre, author of one of the most detailed
looks to date at Quammen’s work, is enthusiastic: Quam-
men’s “gift to the general reader is to make science accessible,
compelling, and, not least important, entertaining.” Her
comments underline the idiosyncrasies of Quammen’s work:
“Certainly Quammen is concerned with those central and
urgent ethical dilemmas that define and unite what may
loosely be known as the ’environmental movement,’ but he
also pauses to consider the ethics of domestic dog owner-
ship,” a reference to his questions about possible ’unnatural’
harm to dogs from their confinement in urban and suburban
areas, “daring to throw darts at one of the most sacred of
American icons, ’man’s best friend.’”
Born in Cincinnati, in 1948, and spending a child-
hood in southwest Ohio as the only boy of three children,
he was the “designated mowist” of the family lawn, a repeated
chore that probably had something to do with the “why
lawns?” kinds of questions about human-nature relationships
that appear so often in his writings . Quammen went on
to earn a B.A. degree in English from Yale University in
1970, and, as a Rhodes scholar, a B. Litt. in 1973 from
Oxford.
The Song of the Dodo (1996), one of Quammen’s most
recent, yet most recognized books, illustrates both his grasp
of current ideas in science and the heat that he (and the
scientists themselves) take when they relate those ideas to
how “humans in all their variousness, regard and react to
the natural world, in all its variousness.” The variety in
human-environment relationships is a basic theme Quam-
men claims for much of his writing. He built the popular
book Song of the Dodoon the less publicly accessible island
biogeography research of Robert MacArthur and E. O. Wil-
Environmental Encyclopedia 3
David Quaamen
son, creating a sharp, clear depiction of the ideas that islands
are bounded, isolated places vulnerable to extinctions, a vul-
nerability repeated as humans create “isolated, island-like
enclaves” in terrestrial ecosystems, places too small, frag-
mented, and isolated to support diverse populations.
This mix of grave warnings of environmental degra-
dation and species extinctions with personal anecdotes and
popular travel writing draws both praise and criticism. His
books are accessible to a wide audience, so the environmental
issues he discusses are widely disseminated, increasing the
public’s awareness. Even reviews in biology journals like
BioScience laud Quammen’s island biogeography book as
“a work in the finest tradition of autobiographical natural
history,” a history traced back to the great naturalists of
the nineteenth century, including Darwin. But Quammen
doesn’t escape the general questions raised by critics of island
biogeography theory of how different land ’islands’ sur-
rounded by land are from islands bounded by water.
Some critics think that Quammen’s accessibility is
based on the sugar-coating of information: “Quammen has
1150
succumbed to the fashionable conceit that ’popular’ science
has to be diluted with travelogue and soap biography.” How-
ever, Bill McKibben, in Audubon magazine, echoed many
others when he proclaimed Song of the Dodo a “masterpiece
of scientific journalism...and a heroic achievement.”
[Gerald L. Young Ph.D.]
F
URTHER
R
EADING
B
OOKS
McEntyre, Marilyn C. “David Quammen.” Vol. 2, American Nature Writers
edited by John Elder. NY: Charles Scribner’s Sons, 1996.
“Quammen, David 1948–.” Vol. 79, Contemporary Authors. Detroit: Gale
Group, 1999.
Wallace, Allison B. “Contemporary Ecophilosophy in David Quammen’s
Popular Natural Histories.” In The Literature of Science: Perspectives on
Popular Scientific Writings edited by Murdo W. William. Athens, GA:
University of Georgia Press, 1993.
O
THER
“Inventory for the David Quammen Papers, 1956–1999 and undated.”
Texas Archival Resources Online. [2002]. <http://www.lib.utexas.edu/taro/
tturb/00159/00159.html>.
R
Rabbits in Australia
Imported into
Australia
in the mid-nineteenth century,
rabbits have overrun much of the country, causing extensive
agricultural and environmental damage and demonstrating
the dangers of introducing non-native
species
into an area.
Before the first humans arrived in Australia, the only mam-
mals living there were about 150 species of marsupials as
well as
bats
, rats, mice, platypuses, and echidnas. The chief
predator in Australia today is the dingo, a wild dog intro-
duced about 40,000 years ago by Australia’s first human
settlers, the Aborigines. When the British settled Australia
as a penal colony in the late 1700s, they brought a variety
of pets and livestock with them, including rabbits.
The problems with rabbits began in 1859, when 12
pairs of European rabbits were released on a ranch. Since
no significant numbers of natural predators were present in
Australia, the rabbit population exploded within a few years.
They overgrazed the grass used for sheep raising, and despite
extensive efforts to reduce and control the population, by
1953 approximately 1.2 million mi
2
(3 million km
2
) were
inhabited by between several hundred million and over one
billion rabbits.
The rabbits have caused considerable damage to Aus-
tralia’s
environment
, especially its native plants and
wild-
life
. Their extensive burrows cause
soil erosion
, and they
eat large quantities of grass and shoots of other plants, devas-
tating native
flora
that birds, insects, and other creatures
depend on for food and cover.
Repeated attempts have been made to exterminate the
rabbits and limit their populations, often by fumigating and
ripping up their burrows, or by using poison bait. The most
effective effortundertaken involved the introduction of myxo-
matosis in the 1950s, a disease that is fatal to rabbits. But after
an initial decline, the rabbit population began to recover, and
much of Australia remained overrun by the animals.
Proponents of eradication say that the most promising
new biological agent to control wild rabbits is know as RCV
(rabbit calicivirus), which is thought to be a new disease, and
1151
has killed farmed rabbits in China and Europe. In its early
stages, it kills over 90% of infected rabbits. In the laboratory,
it has been shown to kill rabbits shortly after infection; and
after 31 different native species were exposed to the
virus
,it
did not appear to be capable of infecting non-target animals.
But the certainty of this is disputed by other scientists, who
worry that release of the virus is “an uncontrollable and unpre-
dictable” biological experiment; that it could eventually jump
the speciesbarrier, especially if it mutates into adifferent form;
and that rabbits will eventually develop
resistance
to the vi-
rus, as they did to myxomatosis.
The elimination of rabbits might even have adverse
consequences, such as removing an important food source
from eagles and other predators who have come to depend
on them. Wild dogs and cats, deprived of their normal
prey, may turn to increased
hunting
of kangaroos and other
marsupials. On the other hand, the number of feral canines
and felines might decline with the demise of an easy and
abundant food source, which would benefit marsupials. So,
the ultimate impact of RCV is not entirely predictable.
There is little danger of an immediate collapse of
the rabbit population. The latest data estimates that the
population has been reduced from about 200–300 million
rabbits to 100 million.
The proliferation of rabbits in Australia has cost the
government and ranchers billions of dollars. This situation
remains a primary example of the harm that can result from
the introduction of non-native species, no matter how seem-
ingly harmless, into a foreign environment.
[Lewis G. Regenstein]
R
ESOURCES
B
OOKS
Ecology of Biological Invasions. New York: Cambridge University Press, 1986.
P
ERIODICALS
Anderson, I., and R. Nowak. “Australia’s Giant Lab.” New Scientist.
Environmental Encyclopedia 3
Rachel Carson Council
Chris Pert, rabbit hunter in Western Australia.
(Photograph by Ulrike Welsch. Reproduced by per-
mission.)
Rachel Carson Council
The Rachel Carson Council focuses on the dangers of pesti-
cides and other toxic
chemicals
and their impact on human
health,
wildlife
, and the
environment
. After the 1962 pub-
1152
lication of her classic book on pesticides, Silent Spring,
Ra-
chel Carson
was overwhelmed by the public interest it gen-
erated, including letters from many people asking for advice,
guidance, and information. Shortly after her death in April
1964, colleagues and friends of Carson established an organi-
zation to keep the public informed on new developments in
the field of chemical contamination. Originally called the
Rachel Carson Trust for the Living Environment, it was
incorporated in 1965 to work for
conservation
of
natural
resources
, to increase knowledge about threats to the envi-
ronment, and to serve as a clearinghouse of information for
scientists, government officials, environmentalists, journal-
ists, and the public.
The Council has long warned that many pesticides,
regulated by the
Environmental Protection Agency
(EPA)
and widely used by homeowners, farmers, and industry, are
extremely harmful. Many of these chemicals can cause
can-
cer
, miscarriages,
birth defects
, genetic damage, and harm
to the central nervous system in humans, as well as destroy
wildlife and poison the environment and
food chain/web
for years to come.
Other, less acutely toxic chemicals that are commonly
used, the organization points out, can cause “delayed neuro-
toxicity,” a milder form of nerve damage that can show up
in subtle behavior changes such as memory loss, fatigue,
irritability, sleep disturbance, and altered brain wave pat-
terns. Concerning termiticides used in schools, “children are
especially vulnerable to this kind of poisoning,” the Council
observes, “and the implications for disturbing their ability
to learn are especially serious.”
Through its studies, publications, and information dis-
tribution, the Council has provided data strongly indicating
that many pesticides now in widespread use should be
banned or carefully restricted. The group has urged and
petitioned the EPA to take such action on a variety of
chemicals that represent serious potential dangers to the
health and lives of millions of Americans and even to
future
generations
.
The Council has also expressed strong concern about,
and sponsored extensive research into, the link between ex-
posure to toxic chemicals and the dramatic increase in recent
years in cancer incidence and death rates. The group’s publi-
cations and officials have warned that the presence of dozens
of cancer-causing chemicals in our food, air, and water is
constantly exposing us to deadly carcinogens and is contrib-
uting to the mounting incidence of cancer, which eventually
strikes almost one American in three, and kills over 500,000
Americans every year.
The Council publishes a wide variety of books, book-
lets, and brochures on pesticides and toxic chemicals and
alternatives to their use. Its most recent comprehensive work,
Basic Guide to Pesticides: Their Characteristics and Hazards
Environmental Encyclopedia 3
Radiation exposure
(1992), describes and analyzes over 700 pesticides. Other
publications discuss the least toxic methods of dealing with
pests in the home, garden, and greenhouse; non-toxic gar-
dening; ways to safely cure and prevent lawn diseases; and
the dangers of poisons used to keep lawns green.
The Council’s board of directors includes experts and
leaders in the fields of
environmental science
, medicine,
education, law, and consumer interest, and a board of con-
sulting experts includes scientists from many fields.
[Lewis G. Regenstein]
R
ESOURCES
O
RGANIZATIONS
Rachel Carson Council, Inc., 8940 Jones Mill Road, Chevy Chase, MD
USA 20815. (301) 652-1877, Fax: (301) 951-7179, Email:
rccouncil@aol.com, <http://members.aol.com/rccouncil/ourpage/
index.htm>
Radiation exposure
Radiation is defined as the
emission
of energy from an
atom in the form of a wave or particle. Such energy is
released as electromagnetic radiation or as
radioactivity
.
Electromagnetic radiation includes radio waves, infrared
waves or heat, visible light,
ultraviolet radiation
, x rays,
gamma rays, and cosmic rays. Radioactivity, emitted when
an atomic nucleus undergoes decay, usually takes the form
of a particle such as an
alpha particle
or
beta particle
,
though atomic decay can also release electromagnetic
gamma rays.
While radiation in the form of heat, visible light, and
even ultraviolet light is essential to life, the word “radiation”
is often used to refer only to those emissions which can
damage or kill living things. Such harm is specifically attrib-
uted to radioactive particles as well as the electromagnetic
rays with frequencies higher than visible light (ultraviolet, x
rays, gamma rays). Harmful electromagnetic radiation is also
known as
ionizing radiation
because it strips atoms of
their electrons, leaving highly reactive ions called free radicals
which can damage tissue or genetic material.
Effects of radiation
The effects of radiation depend upon the type of radia-
tion absorbed, the amount or dose received, and the part of
the body irradiated. While alpha and beta particles have only
limited power to penetrate the body, gamma rays and x rays
are far more potent. The damage potential of a radiation
dose is expressed in rems, a quantity equal to the actual dose
in rads (units per kg) multiplied by a quality factor, called
Q, representing the potency of the radiation in living tissue.
Over a lifetime, a person typically receives 7–14 rems from
natural sources. Exposure to 5–75 rems causes few observable
1153
symptoms. Exposure to 75–200 rems leads to vomiting,
fatigue, and loss of appetite. Exposure to 300 rems or more
leads to severe changes in blood cells accompanied by hemor-
rhage. Such a dosage delivered to the whole body is lethal
50% of the time. An exposure of more than 600 rems causes
loss of hair, loss of the body’s ability to fight infection, and
results in death. A dose of 10,000 rem will kill quickly
through damage to the central nervous system.
The symptoms that follow exposure to a sufficient
dose of radiation are often termed “radiation sickness” or
“radiation burn.” Bone marrow and lymphoid tissue cells,
testes and ovaries, and embryonic tissue are most sensitive to
radiation exposure. Since the lymphatic tissue manufactures
white blood cells (WBCs),
radiation sickness
is almost
always accompanied by a reduction in WBC production
within 72 hours, and recovery from a radiation dose is first
indicated by an increase in WBC production.
Any exposure to radiation increases the risk of
cancer
,
birth defects
, and genetic damage, as well as accelerating the
aging process, and causing other health problems including
impaired immunity. Among the chronic diseases suffered
by those exposed to radiation are cancer, stroke, diabetes,
hypertension, and cardiovascular and renal disease.
Sources of radiation
Some 82% of the average American’s radiation exposure
comes from natural sources. These sources include
radon
gas
emissions from underground, cosmic rays from space, natu-
rally occurring radioactive elements within our own bodies,
and radioactive particles emitted from
soil
and rocks. Man-
made radiation, the other 18%, comes primarily from medical
x rays and nuclear medicine, but is also emitted from some
consumer products (such as
smoke
detectors and blue topaz
jewelry),or originates inthe production and testingof
nuclear
weapons
and the manufacture of nuclear fuels.
Environmental scientists believe that radon, a radioac-
tive gas, accounts for most of the radiation dose Americans
receive. Released by the decay of
uranium
in the earth,
radon can infiltrate a house through pores in block walls,
cracks in basement walls or floors, or around pipes. The
Environmental Protection Agency
estimates that eight
million homes in the United States have potentially danger-
ous levels of radon, and calls radon “the largest environmental
radiation health problem affecting Americans.” Inhaled ra-
don may contribute to 20,000 lung cancer deaths each year
in the United States. The EPA now recommends that home-
owners test their houses for radon gas and install a specialized
ventilation system if excessive levels of gas are detected.
Though artificial sources of radiation contribute only
a small fraction to overall radiation exposure, they remain a
strong concern for two reasons. First, they are preventable
or avoidable, unlike cosmic radiation, for example. Second,
while the average individual may not receive a significant
Environmental Encyclopedia 3
Radiation sickness
dose of radiation from artificial sources, geographic and oc-
cupational factors may mean dramatically higher doses of
radiation for large numbers of people. For instance, many
Americans have been exposed to radiation from nearly 600
nuclear tests conducted at the
Nevada Test Site
. From the
early 1950s to the early 1960s, atmospheric blasts caused a
lingering increase in radiation-related sickness downwind of
the site, and increased the overall dose of radiation received
by Americans by as much as 7%. Once the tests were moved
underground, that figure fell to less than 1%.
A February 1990 study of the Windscale
plutonium
processing plant in Britain clearly demonstrated the impor-
tance of the indirect effects of radiation exposure. The study
correlated an abnormally high rate of
leukemia
among chil-
dren in the area with male workers at the plant, who evidently
passed a tendency to leukemia to their children even though
they had been receiving radiation doses that were considered
“acceptable.”
Recently, the EPA published their National Radon
Results listing studies from 1984 to 1999. This study showed
that 18 million homes have been tested for radon in the
United States. In 1999 alone, there were about 1.4 million
homes tested for radon. The knowledge of radon’s harmful
effects is on the rise (88% of Americans were aware of the
harmful effects in 1999 compared to 73% in 1996) which
is apparently contributing to the increase in testing.
[Linda Rehkopf and Jeffrey Muhr]
R
ESOURCES
B
OOKS
Caufield, C. Multiple Exposures. Harper & Row, Publishers, New York,
1989.
Wagner Jr., H. N., and L. E. Ketchum. Living With Radiation: The Risk,
the Promise. Baltimore: Johns Hopkins University Press, 1989.
P
ERIODICALS
Cobb Jr., C. E. “Living With Radiation.” National Geographic 175 (April
1989): 403–437.
O
THER
Environmental Protection Agency. National Radon Results. June 2002 [cited
July 2002]. <http://www.epa.gov/air/oarnew3.html>.
Radiation sickness
Radiation sickness, also known as acute radiation syndrome
or
ionizing radiation
injury, is illness resulting from human
exposure to ionizing radiation. The
radiation exposure
may be from natural sources, such as radium, or from man-
made sources, such as x rays, nuclear reactors, or atomic
bombs. Ionizing radiation penetrates cells of the body and
ultimately causes damage to critically important molecules
1154
Radiation Sources
Natural Sources
Radon gas 55%
Inside body 11%
Rocks, soil, and groundwater 8%
Cosmic rays 8%
Artificial sources
Medical x rays 11%
Nuclear medicine 4%
Consumer products 3%
Miscellaneous* <1%
* includes occupation exposure, nuclear fallout, and the produc-
tion of nuclear materials for nuclear power and weapons
such as nucleic acids and enzymes. Immediate cell death
may occur if the dose of ionizing radiation is sufficiently
high; lower doses result in cell injury which may preclude
cell replication. Tissues at greatest risk for radiation injury
are those which have cells that are rapidly dividing. Blood
forming cells, the lining to the gastrointestinal tract, skin,
and hair forming cells are particularly vulnerable. Muscle,
brain, liver, and other tissues, which have a low rate of cell
division, are less so.
Epidemiological data on radiation sickness has been
accumulated from the study of individual cases, as well as
from the study of large numbers of afflicted individuals, such
as the survivors of the atomic bombing of Hiroshima and
Nagasaki and the 135,000 people evacuated from close prox-
imity to the fire at the
Chernobyl Nuclear Power Station
in 1986.
In those who survive, radiation sickness may be charac-
terized by four phases. The initial stage occurs immediately
after exposure and is characterized by nausea, vomiting,
weakness, and diarrhea. This is a period of short duration,
typically one or two days. It is followed by a period of
apparent recovery lasting for one to three weeks. No particu-
lar symptoms appear during this time. The third stage is
characterized by fever, infection, vomiting, lesions in the
mouth and pharynx, abscesses, bloody diarrhea, hemor-
rhages, weight loss, hair loss, bleeding ulcers, and petechiae,
small hemorrhagic spots on the skin. During this phase,
there is a loss of appetite, nausea, weakness, and weight loss.
These symptoms are due to the depletion of cells which
would normally be rapidly dividing. Bone marrow depression
occurs with reduced numbers of white blood cells, red blood
cells, and blood platelets. Gut cells that are normally lost
Environmental Encyclopedia 3
Radioactive fallout
are not replaced and hair follicle cells are depressed resulting
in hair loss. If death does not occur during this phase, a
slow recovery follows. This is the fourth phase, but recovery
is frequently accompanied by long-lasting or permanent dis-
abilities including widespread scar tissue, cataracts, and
blindness.
The toxic side effects of many
cancer
chemotherapeu-
tic agents are similar to acute radiation sickness, because
both radiation and chemotherapy primarily affect rapidly
dividing cells. Little effective treatment can be administered
in the event of casualties occurring in enormous numbers
such as in war or a major
nuclear power
plant disaster.
However, in individual cases such as in accidental laboratory
or industrial exposure, some may be helped by isolation
placement to prevent infection, transfusions for hemorrhage,
and bone marrow transplantation. See also Epidemiology;
Nuclear weapons; Nuclear winter; Radiation exposure; Ra-
dioactive pollution; Threshold dose
[Robert G. McKinnell]
R
ESOURCES
B
OOKS
Guskova, A. K., et al. “Acute Effects of Radiation Exposure Following the
Chernobyl Accident.” In Treatment of Radiation Injuries, edited by D.
Browne, et al. New York: Plenum Press, 1990.
Wald, N. “Radiation Injury.” In Cecil Textbook of Medicine, edited by P.
B. Beeson, et al. 15th ed. Philadelphia: Saunders, 1979.
Radioactive decay
Radioactive decay is the process by which an atomic nucleus
undergoes a spontaneous change, emitting an
alpha particle
or
beta particle
and/or a
gamma ray
. Radioactive decay
is a natural process that takes place in the air, water, and
soil
at all times. The decay of isotopes such as uranium-
238, radium-226, radon-222, potassium-40, and carbon-14
produce radiation that poses an unavoidable and, probably,
minimal hazard to human health. Scientists have also learned
how to convert stable isotopes to radioactive forms. The
radioactive decay of these isotopes has been added to the
natural
background radiation
from naturally radioactive
materials. See also Carbon; Radioactive fallout; Radioactivity
Radioactive fallout
In the 1930s, scientists found that bombarding
uranium
metal with neutrons caused the nuclei of uranium atoms to
break apart, or fission. One significant feature of this reaction
was that very large amounts of energy were released during
nuclear fission
. The first practical application of this discov-
1155
ery was the atomic bomb, developed by scientists working
in the United States in the early 1940s.
The atomic bomb takes advantage of the energy re-
leased during fission to bring about massive destruction of
property and human life. However, every bomb blast is also
accompanied by another event known as radioactive fallout.
The term radioactive fallout refers to all radioactive dust and
particles that fall to the earth after a nuclear explosion.
This combination of dust and particles contains hundreds
of isotopes formed when a uranium nucleus fissions. Iodine-
131 and yttrium-98 are only two of the many isotopes that
are formed during an atomic bomb blast.
When these isotopes are formed, they come together
as only very small particles. The force of the blast assures
that large particles will not survive. In this form, the radioac-
tive dust and particles may remain suspended in air for days,
weeks, or months. Only when they have consolidated to
form larger particles will they fall back to Earth.
Once they have reached the earth, these particles face
different fates. Some isotopes formed during fission have
very short half-lives. They will decay rapidly and pose little
or no environmental threat. Others have longer half-lives
and may remain in the
environment
for many years.
The components of radioactive fallout that cause the
greatest concern are those that can take some role in plant
or animal
metabolism
. For example, the element strontium
is chemically similar to the element calcium. Strontium can
replace calcium in many biochemical reactions. That explains
why the following scenario is so troubling.
Strontium-90 released during a fission bomb blast falls
to the earth, coats grass, and is eaten by cows. The cows
incorporate strontium-90 into their milk, just as they do
calcium. When growing children drink that milk, the stron-
tium-90 is used to build bones and teeth, just as calcium
is. Once incorporated into bones and teeth, however, the
radioactive strontium continues to emit harmful radiation
for many years.
The dangers of radioactive fallout are one of the major
reasons that the United States and the former Soviet Union
were able to agree in 1963 on a limited ban of
nuclear
weapons
testing. In that agreement, both nations promised
to stop nuclear weapons testing in the
atmosphere
, under
water, and in outer space. See also Half-life; Radioactive
decay; Radioactivity
[David E. Newton]
R
ESOURCES
B
OOKS
Inglis, D. R. Nuclear Energy: Its Physics and Social Challenge. Reading, MA:
Addison-Wesley, 1973.
Environmental Encyclopedia 3
Radioactive pollution
Jagger, J. The Nuclear Lion: What Every Citizen Should Know About Nuclear
Power and Nuclear War. New York: Plenum, 1991.
Radioactive pollution
Radioactive
pollution
can be defined as the release of radio-
active substances or high-energy particles into the air, water,
or earth as a result of human activity, either by accident or
by design. The sources of such waste include: 1) nuclear
weapon testing or detonation; 2) the nuclear fuel cycle, includ-
ing the mining, separation, and production of nuclear mate-
rials for use in nuclear
power plants
or nuclear bombs;
3) accidental release of radioactive material from
nuclear
power
plants. Sometimes natural sources of
radioactivity
,
such as
radon
gas emitted from beneath the ground, are
considered pollutants when they become a threat to human
health.
Since even a small amount of
radiation exposure
can have serious (and cumulative) biological consequences,
and since many radioactive wastes remain toxic for centuries,
radioactive pollution is a serious environmental concern even
though natural sources of radioactivity far exceed artificial
ones at present.
The problem of radioactive pollution is compounded
by the difficulty in assessing its effects.
Radioactive waste
may spread over a broad area quite rapidly and irregularly
(from an abandoned dump into an
aquifer
, for example),
and may not fully show its effects upon humans and organ-
isms for decades in the form of
cancer
or other chronic
diseases. For instance, radioactive iodine-131, while short-
lived, may leave those who ingest it with long-term health
problems. By the time a radioactive leak is revealed and a
health survey is carried out, many of the individuals affected
by the leak may have already moved from the area (or died
without having been examined with the possible cause in
mind). In addition, since most radioactive materials are un-
der the jurisdiction of governmental agencies—usually in the
secretive defense and military establishments—the dumping
activities and accidental discharges that accompany nuclear
materials production and bomb testing tend to remain con-
cealed until governments are obligated to disclose them un-
der public pressure.
Atmospheric pollution
Radioactive pollution that is spread through the earth’s
atmosphere
is termed fallout. Such pollution was most
common in the two decades following World War II, when
the United States, the Soviet Union, and Great Britain con-
ducted hundreds of
nuclear weapons
tests in the atmo-
sphere. France and China did not begin testing nuclear
weapons until the 1960s and continued atmospheric testing
even after other nations had agreed to move their tests under-
ground.
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Three types of fallout result from nuclear detonations:
local, tropospheric, and stratospheric. Local fallout is quite
intense but short-lived. Tropospheric fallout (in the lower
atmosphere) is deposited at a later time and covers a larger
area, depending on meteorological conditions. Stratospheric
fallout, which releases extremely fine particles into the upper
atmosphere, may continue for years after an explosion and
attain a worldwide distribution.
The two best known examples illustrating the effect
of fallout contamination are the bombing of Hiroshima and
Nagasaki, Japan
in 1945, and the
Chernobyl Nuclear
Power Station
disaster in April 1986. Within five years of
the American bombing of Japan, as many as 225,000 people
had died as a result of long-term exposure to radiation from
the bomb blast, chiefly in the form of fallout.
The disaster at the Chernobyl Nuclear Power Station
in Ukraine on April 26, 1986 produced a staggering release
of radioactivity. In 10 days at least 36 million curies spewed
across the world. The fallout contaminated approximately
1,000 square mi (2,590 sq km) of farmland and villages in
the Soviet Union. Dangerous levels of radioactivity were
reported in virtually every European country, and radioactive
pollutants contaminated rainwater, pastures and food crops.
Radiation alerts were posted in almost every country, chil-
dren were kept indoors, and sales of milk, vegetables, and
meat were banned in some areas. In the Soviet Union alone,
135,000 people were evacuated from their homes. In addi-
tion to the hundreds killed at the time of the explosion,
scientists predict the eventual Soviet death toll from the
Chernobyl accident may reach 200,000; the estimated
mor-
tality
in western Europe may approach 40,000.
Pollution on land and in water
The major sources of radioactive pollution on land
and water include: 1) the nuclear fuel cycle—the extraction,
separation and refinement of materials for use in nuclear
weapons and nuclear power—and 2) the day-to-day opera-
tions of nuclear power plants.
At every stage in the production of nuclear fuels, con-
taminants are left behind. The mining of
uranium
, for
example, produces highly radioactive tailings which can be
blown into the air, contaminate
soil
, or leach into bodies
of water. The magnitude of radioactive pollution caused by
the nuclear fuel cycle, especially in the United States, Great
Britain, and the Soviet Union, has only recently been re-
vealed. Through the years of the cold war, the extent of
accidental discharges and intentional dumping carried out by
government plants like Britain’s Windscale and the United
States’
Hanford Nuclear Reservation
remained largely un-
known. Not until the late 1980s, for instance, was the legacy
of flagrant pollution at Hanford exposed to public scrutiny.
This legacy included the release of half a million curies of
radioactive iodine into the air from 1944 to 1955, and the