xxv
CHAPTER PREVIEW
2.2
FROM SCIENCE TO TECHNOLOGY
Ionizing Radiation: From the Cold War to Yucca Mountain
A
lpha, beta, and gamma radiation are
called ionizing radiation because their
energy removes electrons from atoms
(F
g. 2C). Electrons dislodged by ionizing radiation
can a±
ect nearby atoms, disrupting physiology at
the chemical level in a variety of ways—causing
cancer, clouding the lens of the eye, and interfer-
ing with normal growth and development.
In the United States, some people are
exposed to very low levels of ionizing radia-
tion, mostly from background radiation, which
originates from natural environmental sources
(table 2A). ²or people who live near sites of
atomic weapons manufacture, exposure is
greater. Epidemiologists are investigating medi-
cal records that document illnesses linked to
long-term exposure to ionizing radiation in a
1,200-square kilometer area in Germany.
The lake near Oberrothenback, Germany,
which appears inviting, harbors enough toxins to
kill thousands of people. It is polluted with heavy
metals, low-level radioactive chemical waste,
and 22,500 tons of arsenic. Radon, a radioactive
by-product of uranium, permeates the soil. Many
farm animals and pets that have drunk from the
lake have died. Cancer rates and respiratory disor-
ders among the human residents nearby are well
above normal.
The lake in Oberrothenback was once a dump
for a factory that produced “yellow cake,” a term
for processed uranium ore, used to build atomic
bombs for the former Soviet Union. In the early
1950s, nearly half a million workers labored here
and in surrounding areas in factories and mines.
Records released in 1989, after the reunification
of Germany, reveal that workers were given perks,
such as alcoholic beverages and better wages, to
work in the more dangerous areas. The workers
paid a heavy price: many died of lung ailments.
Today, concern over the health effects of
exposure to ionizing radiation centers on the
u.s. government’s plan to transport tens of thou-
sands of metric tons of high-level nuclear waste
from 109 reactors around the country for burial
beneath yucca mountain, nevada, by 2021. The
waste, currently stored near the reactors, will
be buried in impenetrable containers under the
mountain by robots. In the reactors, nuclear fuel
rods contain uranium oxide, which produces
electricity as it decays to plutonium, which
gives off gamma rays. Periodically the fuel rods
must be replaced, and the spent ones buried.
Environmental groups are concerned that the
waste could be exposed during transport and
that the facility in the mountain may not ade-
quately contain it.
TABLE
2A
|
Sources of Ionizing Radiation
Background
(Natural environmental)
Cosmic rays from space
Radioactive elements in earth’s crust
Rocks and clay in building materials
Radioactive elements naturally in the body (potassium-40, carbon-14)
Medical and dental
X rays
Radioactive substances
Other
Atomic and nuclear weapons
Mining and processing radioactive minerals
Radioactive fuels in nuclear power plants
Radioactive elements in consumer products (luminescent dials, smoke
detectors, color TV components)
FIGURE 2C
Ionizing radiation removes
elecrons from atoms. (
a
) Ionizing radiation
may dislodge an electron from an electrically
neutral hydrogen atom. (
b
) Without its
electron, the hydrogen atom becomes a
positively-charged hydrogen ion (H
+
).
+
+
(b)
Hydrogen ion
(H
+
)
Dislodged
electron
Ionizing
radiation
(a)
Hydrogen atom
(H)
In a
hiatal hernia,
part of the stomach protrudes through a weakened
area of the diaphragm, through the esophageal hiatus and into the
thorax. Regurgitation (re³
u×) of gastric juice into the esophagus may
in³
ame the esophageal mucosa, causing heartburn, di´
culty in swal-
lowing, or ulceration and blood loss. In response to the destructive
action of gastric juice, columnar epithelium may replace the squamous
epithelium that normally lines the esophagus (see chapter 5, pages
147–148). This condition, called
Barrett’s esophagus,
increases the risk
of developing esophageal cancer.
Sometimes in your reading you will be directed back to a
related concept, discussed in an earlier chapter, to help you
better understand the new concept that is being explained.
RECONNECT
To Chapter 11, Sympathetic Division, pages 424–426.
As you read, you may feel the need for a “study break.”
Sometimes you may just need to “chill out.” Other times, you
may just need to shift gears. Try the following! Throughout
the book are shaded boxes that present sidelights to the
main focus of the text. Indeed, some of these may cover
topics that your instructor chooses to highlight. Read them!
They are interesting, informative, and a change of pace.
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