United States Criteria & Standards Division
Environmental Protection EPA 570/9-81-002
Agency January 1981
Water
Radioactivity
in Drinking Water
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RADIOACTIVITY IN DRINKING WATER
HEALTH EFFECTS BRANCH
CRITERIA AND STANDARDS DIVISION
OFFICE OF DRINKING WATER
US ENVIRONMENTAL PROTECTION AGENCY
Washington, D.C.
January 1981
U.S. Environmental Protection Agency
Region V, Library
230 South Dearborn Street , -
Chicago, Illinois 60604
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INTRODUCTION/ABSTRACT 1
I PHYSICAL CHARACTERISTICS OF RADIOACTIVITY
A GENERAL NUCLEAR PROPERTIES 3
B UNITS OF RADIOACTIVITY 14
II HEALTH EFFECTS OF RADIOACTIVITY
A GENERAL 20
B HEALTH EFFECTS 30
C RISK 40
III CONTROL METHODS FOR RADIOACTIVITY IN DRINKING WATER 45
IV RADIATION REGULATIONS
A GENERAL 49
B NATURAL RADIOACTIVITY 51
C MAN-MADE RADIOACTIVITY 53
D VARIANCES AND EXEMPTIONS 59
REFERENCES 62
GLOSSARY 65
APPENDICES
I CHEMICAL ELEMENT SYMBOLS AND ATOMIC NUMBERS 69
II NATURALLY OCCURRING RADIOACTIVE SERIES 70
III CONCENTRATIONS YIELDING 4 mrem/yr DOSE 73
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INTRODUCTION/ABSTRACT
This general overview is designed to assist those
involved with public health and drinking water (public
health officers, officials, medical personnel, local, state
and federal administrators) to better understand, interpret
and implement EPA's regulations for radioactivity in drinking
water. A public health official is often the one who receives
a distressed call from a local water supply official who has
just received the analysis of radioactivity in the local
drinking water supply. Several questions come up such as:
What is a curie?
What do the numbers mean?
How bad is it?
What does that do to people?
Why haven't we noticed this before?
What evidence do you have that that really happens?
How many effects can we expect and how soon?
What must we do immediately?
What can we do to solve the problem?
How much will it cost?
How does this risk compare to others?
In this presentation the general nuclear properties are
shown by using naturally occurring isotopes such as radium,
radon and uranium as examples. The units of radioactivity
(curie, rad, rem) are explained and demonstrated in describing
natural radiation in our surroundings and bodies as well as
man-made radiation from medical x-rays, TV, fallout, indus-
trial uses and nuclear power plants and other sources. The
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health effects discussed include birth defects, genetic
damage, cancers, leukemias and others. Several specific
examples are given in each disease area as well as their
relative importance or rate of occurrence. The risk (in
deaths/million people exposed/yr) is tabulated for radio-
activity and compared to several other causes including
disease, accidents and weather. Possible methods for reducing
the radioactivity in drinking water are described and include:
alternate well construction and treatment such as softening
and reverse osmosis. Flow charts are provided that show how
to interpret measurements of radioactivity in drinking water
and what additional measurements may be required.
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I PHYSICAL CHARACTERISTICS OF RADIOACTIVITY
A GENERAL NUCLEAR PROPERTIES
An atom consists of a heavy concentration of mass at
the center (the nucleus) surrounded by shells of electrons
in different orbits (see Figure 1). The primary constituents
of the nucleus are neutrons and protons. The neutrons have
no charge while the protons have a positive charge. The
orbital electrons have a negative charge and are equal in
number to the protons, making the atom neutral in overall
charge. Of the several orbits an electron can occupy, each
orbit has a maximum number of electrons that it can hold.
How atoms interact with each other (i.e. their chemistry)
depends upon how many electrons are in the outermost orbit.
Due to the energy requirements of the atom, electrons tend
to fall into lower orbitals first until the maximum number
for that orbit is achieved. Higher orbits are then filled
in succession. By the input of energy, electrons can be
moved to outer orbits. They will spontaneously "fall" to
lower orbits, much like water flows downhill, until the
maximum number for that orbit is reached. The energy lost
in this process is emitted as light or x-rays.
For example, the characteristics of the noble gases can
be understood using the idea of electron orbits. They all
correspond to filled outer electron orbits. If the first
orbit is filled the atom is helium (He). When the orbits
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NUCLEUS
ORBITAL
ELECTRONS
Figure 1 Schematic drawing of an atom. The example
given here is one of the simpler elements
called lithium.
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are each completely filled the atom has greater stability or
is less reactive -- hence the inert gases. (The names of
the elements and their chemical symbols are shown in Appendix
I). If the first and second orbitals are filled, the element
is neon. This sequence continues through Argon (Ar), Krypton
(Kr), Xenon (Xe), and Radon (Rn). Radon is a gas and is
both inert and radioactive. There are different kinds
(isotopes) of radon determined by the number of neutrons in
the nucleus.
The chemical properties of an atom are determined by
the electrons, because these are the parts of the atom that
can come close enough to interact with other atoms under
normal circumstances. The atom in Figure 1, because it has
three protons and three electrons, is a lithium atom. It is
lithium regardless of the number neutrons in the nucleus or
.electrons in the orbits.
Atoms are grouped into chemical families. The lithium
atom in Figure 1 has two electrons in one orbit and a third
in the outer orbit. Other atoms with a single outer electron;
sodium, potassium, rubidium and cesium, will have chemical
properties similar to (but not identical with) those of
lithium-. Radium, which has two outer electrons, behaves
like calcium, which also has two outer electrons. For
example, radium, like calcium, becomes incorporated into
material such as bone.
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The number of protons in the nucleus determines the
element and its atomic number, as shown in Appendix I. A
given element can have more than one particular number of
neutrons. Variation in the number of neutrons does not
change the chemical properties (the element is the same) but
it produces considerable change in the stability of the
element to radioactive decay. Atoms with the same number of
protons but different number of neutrons are called isotopes,
For example, if an atom has 86 protons, it is radon. There
are three well known isotopes of radon containing 133, 134,
and 136 neutrons. The atomic mass number is the total
number of protons and neutrons in the nucleus and this sum
is usually used to label isotopes. The three isotopes of
radon have atomic masses of 86 + 133 = 2:19, 86 + 134 = 220
and 86 + 136 = 222. Symbolically these can be written as:
,, 22(5 222,,
86Rn 86Rn 86Rn
Since the atomic number of protons and the chemical symbol
are synonomous, the number of protons is usually omitted in
the nomenclature. The common isotopes of radon are usually
written as:
21V 22°Rn 222Rn
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Note that it is also acceptable to write them as:
D 219 _ 220 _ 222
Rn Rn Rn
or:
Rn-219 Rn-220 Rn-222
the latter form being used where superscripts are awkward.
The atomic mass numbers are not the exact masses of the
atom. They only reflect the total number of neutrons and
protons. They are, however, rough approximations of the
actual masses. The energy released in radioactive decay
comes from the differences in the actual masses through
2
Einstein's well known equation -- E - me . In this equation
E is the energy, m the mass and c is a constant; viz, the
speed of light.
It is a general rule of nature that a system will try
to attain the lowest energy state or the most stable situa-
tion possible; e.g. water runs downhill, unlike charges
attract each other causing an electron to "fall" into the
orbit closest to the nucleus; snow falls to the ground. In
this same sense/ if a nucleus can move to a lower energy
state by emitting radiation — it will. Such a nucleus is
radioactive compared to other nuclei which may be stable,
and unable to lose energy by emitting radiation.
In general one might expect the nucleus to be able to
emit all different kinds and combinations of radiations.
However, because of this trend to stability and the nature
of the nuclear force, the most likely (or most stable)
radiations to be ejected are:
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Emitted Particles Process Radiation Type
helium nucleus (two protons alpha decay alpha particle
plus two neutrons)
electron beta decay beta particle
a kind of high energy gamma decay gamma ray
x-ray
An alpha particle, the heaviest nuclear radiation,
consists of two protons and two neutrons (A proton or neutron
is about 2,000 times as massive as an electron). A beta
particle is an electron emitted from the nucleus as a result
of neutron decay. An electron can be "created" and ejected
from a nucleus by a neutron decaying into a proton (which
remains in the nucleus) and an electron (which is ejected as
a beta particle). As a result of this process the nucleus
has one more proton and thus has become the atom of a different
element with atomic number one greater than the parent atom.
A gamma ray is a form of electromagnetic radiation. Other
forms of electromagnetic radiation are light, radio waves,
infrared radiation, ultraviolet radiation, and x-rays.
The process of alpha and beta radioactive decay leads
to a different element while gamma decay does not. The
isotope that decays is called the parent. The resulting
8
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isotope (if a different element) is called the daughter.
222
For example, Rn decays by emitting an alpha particle to
218
the daughter Po (see Appendix II). This reaction is
written:
222 218
where the atomic numbers and atomic mass numbers have been
included and the alpha particle is written in with its
atomic numbers. Note that the atomic numbers and atomic
mass numbers balance on the two sides of this equation.
Note that the atomic mass decreased by 4 due to the loss of
two neutrons and two protons, and the atomic number decreased
by 2 due to the loss of two protons. Beta decay causes the
atomic number to increase by one. Beta decay can be described
as a neutron in the nucleus converted to a proton. An
O O Q O O Q
example of beta decay is Ra which decays to Ac. This
reaction is written:
228R 228,
88Ra > 89AC
where the greek symbol is used for the beta particle and the
minus sign shows that it is an electron. The atomic numbers
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and atomic mass numbers balance in this equation since the
atomic number for an electron is -1 and its atomic mass
number is zero. Gamma decay changes neither the atomic
number nor the element; it only involves a loss of energy.
Alpha, beta and gamma radiations have many different
energies and masses and thus produce different effects as
they interact with matter. Each of these radiations are
capable of knocking an electron from its orbit around the
nucleus and away from the atom. This process is called
ionization. If an electron is moved to an orbit further
from the nucleus the atom is said to be excited. The atom
will then decay by the electron returning to the inner orbit
and emitting radiation. We see this kind of radiation from
a light bulb.
It is by ionization that radiation is detected.
Moreover the process can be beneficial to humans through
therapeutic and diagnostic medicine. The ion being highly
reactive permits easy detection. The highly reactive ion
can also lead to deleterious effects in humans such as
cancers and leukemias. Alpha, beta and gamma radiations can
be ionizing and are the subject of this discussion. (Among
non-ionizing radiations are electromagnetic radiations such
as light, microwaves and radio waves.)
Not all atoms are equally stable and different isotopes
characteristically decay at different rates. The concept of
10
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half life is used to quantitatively describe these differences.
The half life of an isotope is the time required for one
half of the atoms present to decay. Half lives can range from
238
billions of years or more (the half life of u is 4.5 x
9 214
10 yr) to millionths of seconds (the half life of po is
164 x 10 sec) and even less.
Another way to describe the differences between the
nuclear radiations is their ability to penetrate matter. A
comparison is shown in Figure 2. In general most alpha
particles can be stopped by a piece of paper while most
gamma rays can pass through the human body (as do x-rays).
The fact that the alpha particle can be stopped in such
short distances, shows that it deposits more energy in a
small distance; this does more damage per unit volume than
the other radiations.
40
Many isotopes exist naturally such as the K in our
14
bodies, the C produced by cosmic rays used to date old
manuscripts and the naturally radioactive series (see
Appendix II). There are three naturally occuring radio-
active series: the uranium, thorium and actinium series.
These series involve a sequence of alpha and beta and gamma
decays involving heavy nuclei. They start respectively with
900
°
U, Th and U and all end with a different stable
isotope of lead (Pb). In the middle of each series a dif-
ferent isotope of the gas radon (Rn) is formed. The implica-
tion of a gas being formed is important to human health
11
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10cm 1m 10m 100m 1000m
Figure 2 Range of nuclear particles in air with the same energy (3 MEV)
Note that the scale is logarithmic.
12
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since gasses have more freedom to move. For example, if
226 222
Ra is present in drinking water, and decays to Rn, it
may enter a home within the drinking water, and enter the
body by inhalation.
Since each member of a radioactive series decays at a
different rate they may not all be present in the same
amounts. The series might be thought of as a series of
different sized funnels in sequence, with the smaller spouts
representing the longer lifetimes. There is a possibility
that the isotopes may decay from rocks into adjacent ground
water aquifers. In this process the parent isotopes could
remain in the rock, while the daughters move into the water
by recoil due to decay of the alpha particle. The parent
and daughter nuclei are different elements and thus will
likely move and react chemically at different rates. The
relative amounts of parent and daughter nuclei could be
different from what they would be were they both in the
rock. For this reason it is essential to know how much of
each isotope is in the water. All members of a series that
are important to human health need to be monitored.
Fission can also contribute radioactivity to drinking
water. This process, the source of immense energy, is
triggered by adding a neutron to certain nuclei. The phe-
\
nomenon occurs for heavy nuclei, the classical examples
235 232 239
being U, Th and Pu. When a neutron is added, each
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of these isotopes break into two roughly equal parts. Each
of the parts (called fission fragments) is itself a radio-
active nucleus and decays through a sequence of isotopes by
beta and gamma decay. Whether a radioisotope is man-made or
naturally occurring can be determined on the basis of alpha
particle emissions. A naturally occurring decay series
includes alpha emissions, while a man-made radioisotope
involves a decay series lacking in alpha emissions (except for
the heavy transuronic elements).
B UNITS OF RADIOACTIVITY
Generally units such as mg/1, micrograms/liter or ppm
are used to describe the concentrations of pollutants,
toxic and hazardous substances. However,, certain unique
properties of radioactive substances preclude the use of
these units and require different units to directly compare
the health effects of different radionuclides.
Three important, units are needed to describe radio-
activity:
- how many radiations are emitted per second (or decays/
sec or disintegrations/sec)
- how much punch the tissue receives or energy imparted
to matter (called dose)
- how much biological damage is done by the radiation
For radioactivity the number of particles emitted (alpha,
beta or gamma) is what does the damage and not the mass of the
14
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radionuclides. Thus it is essential to have a unit that
describes the activity or number of particles emitted. The
activity is related to the half life, and thus longer half
lives mean lower activity. By definition one gram of radium
is said to have 1 curie (1 Ci) of activity. By comparison,
2 38
1 gm of U has an activity of 0.36 millionth of a curie
(or 0.36 microcurie - see Table 1 and Appendix II).
The effect of radioactivity depends not only on the
number of radiations emitted/sec but on the kind of radiations
(alpha, beta or gamma) and their energies. These latter two
properties are described in terms of the dose or punch given
to tissue or matter.
A common unit of dose (or radiation absorbed) is called
the rad, and one rad deposits one hundred ergs (a metric
unit of energy) in one gram of matter (to get perspective on
the size of an erg, 10 million ergs/sec is one watt). In
general these units are quite large and engineering shorthand
is used to describe the day-to-day activities. Table 1
gives the meaning of some useful and commonly used prefixes.
Thus a millimeter is one thousandth (1/1000) of a meter and
a kilogram is a thousand grams. Similarly 1 picocurie is a
million millionth of a curie and is abbreviated 1 pCi. Also
1 millirad (1 mrad) is one thousandth of a rad. These
latter are common levels of activity and radiation strength
found relating to drinking water. (The Roentgen (R) is a
\
similar unit used in describing x-ray and gamma ray exposure.
The basic differences between the R and the rad centers
around a unit of exposure vs. a unit of energy absorption.)
15
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Table 1 Engineering shorthand and greek prefixes.
GREEK PREFIX
mega
kilo
milli
micro
nano
pico
femto
ABBREVIATION
M
k
m
U
n
P
f
VALUE
1,000,000
1,000
1
1000
1
1,000,000
1
1,000,000,000
1/1,000,000,000,000
1/1,000,000,000,000,01
ENGINEERING
SHORTHAND
10*
10'' ONE PART PER THOUSAND
10"" ONE PART PER MILLION(ppir
10 ONE PART PER BILLION(ppb)
10'"
io-1§
16
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Because of the particle mass and charge, 1 rad of alpha
particles creates more damage than 1 rad of gamma rays. To
compensate for this difference in effect a new unit is
invented — the rem, for radiation equivalent man. This is
called the dose equivalent. The dose is measured in rads
and the dose equivalent is measured in rem. Frequently,
however, the rem is called the dose. The dose equivalent is
a measure of harm and is not generally an exact measurement;
it is a useful administrative unit. The rad and rem are
related by a quality factor as follows:
number of rems = Q times the number of rads
where Q is the quality factor which has been assigned the
following value:
Q = 1 for beta particles and all electromagnetic radiations
(gamma ray and x-rays)
= 10 for neutrons from spontaneous fission and protons
= 20 for alpha particles and fission fragments
(The quality factor for alpha particles was taken
to be 10 at the time regulations were promulgated
(9)
for radioactivity in drinking water.) '
The average human in the U.S. receives from cosmic rays
(high energy protons from outside the earth) and natural
backgroundx radiation about 100 mrem/yr . This can vary
depending on where one lives and the kind of a structure in
which one lives and works in. The higher the altitude, the
17
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less protection we get from the earth's atmosphere. Thus
people in Leadville, Colorado receive from cosmic rays 110
mrem/yr while people at sea level (like Washington, D.C.)
receive about 20 mrem/yr. Flying coast~to-coast can add as
much as 5 mrem per flight.
A selected population in the U.S. is subjected to
diagnostic x-rays that will contribute about 80 mrem/yr on
the average over the whole population. A smaller group will
receive additional exposure to ionizing radiation from the
diagnostic use of nuclear isotopes and a still smaller group
is exposed to therapeutic ionizing radiation (as in cancer
treatment). People who receive radioiodine treatment of
thyroid condition can give their family members a dose as
(2)
high as 2,000 mrem . Color TV can lead to exposures as
high as 1 mrem/yr. Fallout from nuclear weapons testing may
contribute a few mrem/yr and effluents from nucler power
plants may contribute a small fraction of a mrem/yr. Exposure
from dental x-rays and occupational exposure to small groups
contribute additional dose. From the sum of these exposures,
the population in the U.S. is exposed to an approximate dose
of 200 mrem/yr. Table 2 lists the sources of human exposure
to radiation.
Although the background radiation level can vary con-
siderably with altitude, few people live at high altitudes.
Thus roughly two thirds of the population of the U.S. receives
(3)
a dose of ionizing radiation in the range 180-220 mrem/yr .
The statistical geographical variation (two standard deviations
for this case) is 8.5 mrem/y
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Table 2 Sources of radiation for people in the United States.
SOURCE
NATURAL RADIATION
COSMIC RAYS 45
EXTERNAL SURROUNDINGS 40
INTERNAUMAINLY 40K FROM 2Q
FOOD AND DRINKING WATER)
MAN-MADE RADIATION
DIAGNOSTIC X-RAYS 80
RADIOPHARMACUTICALS 16
FALLOUT 3
NUCLEAR POWER PLANTS 0.1
COLOR TV 1
MINING AND MILLING U AND 5
PHOSPHATE ROCK
OCCUPATIONAL EXPOSURE 0.8
CONSUMER PRODUCTS 0.3
TOTAL APPROXIMATELY 200 mrem/yr
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II HEALTH EFFECTS OF RADIOACTIVITY
A GENERAL
Knowledge regarding the health effects of doses of
ionizing radiation requires data concerning the relationship
between dose and effect in humans. However, for moral
reasons we cannot deliberately expose humans to radiation on
an experimental basis. Thus we have to depend on information
from experiments with animals or from epidemiological studies
on human exposure to ionizing radiation. There are diffi-
culties and problems with both of these approaches. In
spite of these difficulties, much is known about the effects
of ionizing radiation in humans.
The effect of any injury or insult to a human may not
be the same as that to animals and vice versa. Rats and
mice seem unaffected by tobacco smoke but humans can develop
lung cancer from smoking. Perhaps the most toxic substance
known for animals - 2,3,7,8 tetrachlorodi.benzo-p-dioxin
(popularly called dioxin) is much less toxic in humans
Effects in animals do not in general scale up for humans
Thus doubling the dose for an animal twice as large may not
produce the same effect. The effect cannot be simply predicted
by the proportionality of the weight. Thus, the biological
differences between humans and animals impede accurate
prediction of the effect on humans based on the effect in
animals. In fact, assuming that what affects animals will
also affect humans can be wrong. However, it is an EPA
policy to use animal data in setting standards for humans.
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Although the effects of ionizing radiation on humans is
much better known than the effect of many other environmental
pollutants, it cannot accurately and definitely be predicted
from known animal effects. An example of this problem is
the genetic effects of ionizing radiations on survivors of
the atomic bomb explosions at Hiroshima and Nagasaki. The
incidence of genetic effects in the descendants has been far
less than is predicted based on animal studies.
There are problems in determining effects on humans
based on epidemiological studies. Perhaps the largest
difficulty is the inaccuracy or incompleteness of the cause
of death on death certificates. For example, heart attack
caused by the strain of another disease might appear on the
death certificate as the cause of death rather than the
infirmity producing the strain. In most cases the actual
dose received is not well known. In general this kind of
information suffers from lack of control. There are many
variables and it may not be clear if the effect is really
due to ionizing radiation or another cause.
Our bodies may be exposed to both external and internal
radioactivity. For exposures to drinking water, the internal
exposures are the most important. Once a radioisotope
enters the body by ingestion or inhalation (in the case of a
gas such as radon), it will move to locations determined by
the body's metabolism and chemistry. In some locations such
as bone, it remains for relatively long periods of time. In
others, it may pass through in relatively short-periods of
21
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time. The time duration for the body to eliminate one half
the original concentration is called the biological half
life, while depending on the isotope may vary from minutes
to years. In any case, different parts of the body can
receive differing doses of radiation. Note that the biological
half-life is not the same as the radioactive half-life.
Biological half-life is a property of the body and radioactive
half-life is a property of the nucleus.
Dosimetric models have been developed to determine the
dose delivered to each part of the body from an ingested or
inhaled radioisotope. The two models of importance to
drinking water are ingestion (the gastro-intestinal model)
(8)
and inhalation (the lung model) . The lung model is
important because each naturally occurring radioactive
series includes a gas (radon) which can be released from
water sources in the home and ultimately inhaled by the
occupants. These models are described in more detail in the
(9)
ICRP publication number 30 .
The gastro-intestinal (G.I.) model separates the G.I.
system into four parts; the stomach, small intestine, upper
large intestine and lower large intestine. The model then
follows the radioactivity into the blood and organs. A
»
biological half life is associated with e:ach of these compart-
ments along with the radioactive half life. Other important
\
variables considered are as follows: the chemical compound
22
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of which the isotope is a part (e.g., carbonate, protein,
sulfate etc.), the age of the person involved, and whether
the daughter products are radioactive and/or toxic (e.g.,
the series end at lead which is stable radioactively but is
toxic chemically). With this model, as with most others,
the greatest contribution to uncertainty is the lack of
"knowledge of the body's metabolism. Other degrees of
uncertainty derive from neglecting consideration of chemical
toxicity and restricting the consideration of health effects
to the nearest tissue and bone. Thus, in the gastro-intestinal
(GI) tract, normally only the mucosal layer is considered,
and for bone exposure, only the top 10 micrometer layer of
bone surface is considered.
Current model estimates indicate that the ingestion of
10 pCi/day of radium (or 5 pCi/1 if 2 I/day is consumed)
produces a dose of 150 mrem/yr to the skeletal bone .
Using models the dose resulting from the maximum intake of
several man-made isotopes is shown in Appendix III.
Two ways of categorizing exposure are whole body dose
or dose to a critical organ. The former is important when
the radiation is external; however, a radioisotope inside the
body often migrates primarily to a certain organ, called the
critical organ. Some examples of metabolic fates
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of several isotopes are shown in Table 3. Some organs are
far more sensitive to radiation than others. Therefore the
exposure or dose allowed to the whole body (all organs) may
be different than the dose allowed to the individual organs.
At levels above 100 rem total dose equivalent, dele-
terious effects in humans can usually be observed. For low
doses, such as those of the order of background radiation
level, there is no well demonstrated observable adverse
effect. (See Table 4) . One problem in determining the
dose-response curve is that the probability of an effect at
low levels is very small (on the order of one in a million).
Therefore, in order for health effects studies to be statisti-
cally valid, the number of people exposed would have to be
on the order of hundreds of millions, or more. Also, many
of the deleterious effects can occur spontaneously, or from
causes other than radioactivity, the numbers of people
exposed that is required by the statistical analysis is
prohibitively large. Thus, we may never be really sure what
the effects of low level radiation are. An overview of the
current understanding of the dose effect relationship is
shown in Figure 3.
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Table 3 Some examples of organs favored by particular elements
ELEMENT CRITICAL ORGAN
Ra BONE
I THYROID
U KIDNEY
Sr BONE MARROW
Co LOWER LARGE INTESTINE
STOMACH
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Table 4 Effects for various doses of ionizing radiation.
The effects for chronic exposure are annual estimates.
ABSORBED DOSE(rem) EFFECT
ACUTE EFFECTS
10,000 DEATH IN A FEW HOURS
1,200 DEATH IN SEVERAL DAYS
600 DEATH IN SEVERAL WEEKS
450 LD 50/30 U-ETHAL DOSE TO 50% IN 30 DAYS)
100 POSSIBLE TEMPORARY IMPAIRMENT BUT
PROBABLE RECOVERY
CHRONIC EFFECTS(predicted)
5 60-1000 GENETICALLY DETERMINED ILLNESSES
PER MILLION PEOPLE EXPOSED
1 100-200EXCESS CANCERS PER MILLION PEOPLE
EXPOSED
1-10 LOWEST LEVEL FOR WHICH DELITERIOUS CHRONIC
EFFECTS HAVE BEEN DEMONSTRATED
0.15 THIS DOSE EQUIVALENT TO THE BONE CAUSES
100 EXCESS CANCERS PER MILLION PEOPLE
EXPOSED PER LIFETIME
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The problem described in Figure 3 is to determine what
the relationship is between the dose level and the effect
for low doses. If the known curve is as shown for number 1
then it is possible that a linear extrapolation is correct
(Curve b). A curvilinear (quadratic) extrapolation (Curve
c) is also possible. However if there is a level below
which no effect occurs (threshold) then Curve d might be
correct. If the dose-effect curve is steep as shown in
Curve 2 then the linear extrapolation (Curve b) might overesti-
mate the effect whereas the extrapolation d might be more
reasonable. Curve a suggests that the effect can be higher
than the linear extrapolation.
The assumption that EPA feels is prudent and advisable
is linear, no threshold (Curve B). It is felt that this is
most likely a conservative approach and probably if anything
overprotective. Thus knowing that there is insufficient
information to determine the effect of low doses of ionizing
radiations on humans, the possible effects are estimated
using a linear extrapolation from data for high doses.
27
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DC
DC
O
UJ
u.
u.
ill
a
/
DOSE OF RADIATION
Figure 3 Different possible dose-effect curves for low
level ionizing radiation.
The dashed lines are for the dose range where
the effects are not known.
28
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Although the effects at low doses are not known, the
linear extrapolation from high doses can provide some numbers
to work from. Figure 4 shows the number of deaths for
annual exposure of a million people to radium in the drinking
water. The assumption used to generate the curve is the
linear, non-threshold one and it must be understood that it
does not represent actual data. Using this curve one can
get a rough idea of the possible effects of radium in drink-
ing water if the linear non-threshold assumption is valid.
B HEALTH EFFECTS
There are three general areas where radioactivity
produces deleterious effects on humans. (Reference 12 is a
general reference for health effects). Some examples of the
effects in these areas are:
Developmental and Teratogenic Effects
Effects on the Fetus
Developmental Abnormalities (skeleton and central
nervous system)
Embryo Lethality
Genetic Effects (effects in subsequent generations)
Mutagenic Changes in DNA
Hereditary Effects
Diseases Caused by Mutations
Dominant/Recessive Diseases
Chromosomal Anomalies
Somatic Effects (effects in the person exposed)
Carcinogenesis (including Leukemia)
Cataract of the Lens of the Eye
Non-malignant Damage to the Skin
Gonadal Cell Damage/Impairment of Fertility
Life Span Shortening
29
-------
cc
-------
The acute effects of ionizing radiation appear within
30 days as a variety of tissue changes or syndromes. Some
effects are lethal and some are not.
Doses of 100,000 rad or more to animals usually cause
inactivation of many substances needed for the basic metabolic
processes of the cell and tissues and thus lead to an immediate
death. Doses of about 10,000 rad produce hyperexcitability,
incoordination, respiratory disease, possible damage to the
nervous system and lead to death in a day or two. In the
dose range from 900 to 10,000 rad, most animals die in 3 to
5 days due to morphologic changes or damage to the gastroin-
testinal (GI) tract. For doses in the range of 300 to 900
rad, death usually occurs in 10 to 15 days due to alterations
in blood cells and blood forming organs (hematopoietic
system).
Exposure of humans to doses at 50 rad or greater lead
to radiation sickness. This is characterized by headache,
dizziness, malaise, abnormal sensations of taste or smell,
nausea, vomiting, diarrhea, decreased blood pressure, decrease
in white blood cells and blood platelets, increased irri-
tability and insomnia. Exposures of several thousand rads
or more cause shock, abdominal cramps, cyanosis, coma and
death. For doses in the range of 500 to 2000 rads, normal
food and fluid intake is depressed, followed by dehydration,
hemoconcentration, circulatory collapse and death. Nausea
31
-------
vomiting, and some diarrhea can be the result of exposures
of less than 500 rads. The body then seems to recover.
But, a few weeks later there is an onset of chills, fatigue,
petechial hemorrhages in the skin and ulceration of the
mouth, pharnyx and intestine, impairment of immune mechanisms
and hemorrhagic ulceration permitting entry of bacteria.
Death, if it occurs, is usually between the third and sixth
week.
Embryos have been shown to be especially susceptible
to ionizing radiation. Those exposed in utero at Nagasaki
and Hiroshima showed microcephaly (small brain) and mental
retardation. Other exposed children suffered from congenital
dislocation of hips, mongolism and congenital heart disease.
The nervous system of humans is usually found to be
extremely radio-resistant in terms of morphologic changes
but does demonstrate a variety of physiologic responses to
relatively low doses of radiation. These effects include
changed reception activity of the eye and changes in condi-
tional reflex activity.
To understand genetic effects, let us examine how life
begins. The creation of new life is determined by the union
of sperm cell and egg cell forming a single fertilized egg.
This is followed by millions of cell divisions.. The blue-
print for these cell divisions and for how the new life
32
-------
grows and develops is found in the DNA molecule. The DNA
molecule is a double helix string of atoms and carries the
basic genetic information. As can be seen in Figure 5, the
basic units of the DNA molecule are four bases labeled G, C,
A and T. The chemical composition of the DNA molecule is
seen more completely in Figure 6 where the polygons repre-
sent carbon rings (a carbon atom at each unmarked corner).
Ionizing radiations can change the structure of the DNA
molecule by changing the way the atoms are bonded or
connected together (this occurs through the atomic electrons).
For example two bases such as T could be in adjacent steps
instead of alternate steps as shown in Figure 6. In that
case ionizing radiation could break an electronic bond and
the T bases would bond to each other instead of the structure
as shown. Following that change the cell divisions would
follow the new blueprint determined by the new DNA structure.
This new pattern follows a new genetic blueprint and almost
always leads to deleterious effects.
The effect of nuclear radiations important for human
health effects is the ability to ionize atoms. The direct
effect is thought to be ionization of the atoms of DNA in
the cell and thus to change the cell's behavior. An indirect
effect"may occur when water in the cell is ionized. Human
cells are about 75% water and when water is ionized it can
produce the highly reactive HO ion (called the hydroxyl free
radical). The HO can attack the DNA and do damage to it.
33
-------
Figure 5 •:',. schematic representation of the DNA double helix.
34
-------
Figure 6 The DNA molecular structure. The base pairs
are shown connecting the backbone like rungs
of a ladder. The dots represent hydrogen
like bonds.
35
-------
Agents that can change the genetic code (called mutagens)
can be found inside our bodies (the mechanisms are not well
understood) or external to our bodies. External mutagenic
agents include chemicals, drugs, elevated temperatures and
ionizing radiation.
Genetic effects of ionizing radiation include abnormalities,
recessive diseases (where both chromosomes in the pair have
some defect) and chromosome damage. Some examples of these
maladies are listed below:
Abnormalities
extra fingers and toes
short lived dwarfism
progressive involuntary movements
mental deterioration
several kinds of anemia
Recessive Diseases
PKU — a form of mental deficiency
Tay Sach's Disease (leads to blindness and death
in the first few years of life)
Sickle Cell Anemia
Cystic Fibrosis
Recessive Mutations Located in the X Chromosome
(noted almost exclusively in males, since
males only have one X chromosome)
Hemophilia
Color Blindness
A Severe Form of Muscular Dystrophy
Chromosome Damage
Too many or too few can lead to embryonic death
or miscarriage
Broken Chromosomes can be involved in:
Diabetes
Schizophrenia
36
-------
In general it is believed that mutations, whether spon-
taneous or induced, can be harmful even though the harm may
be trivial and the effect may not show up for hundreds
of generations. In general each new harmful mutant is even-
tually eliminated by reduced viability or gene extinction.
The number of mutations appears to be proportional to
dose and since spontaneous mutations do occur, the concept
of doubling dose is used; specifically, the doubling dose is
that dose of ionizing radiation that will produce mutations
equal in number to those spontaneously occurring. The
doubling dose is in the range 20-200 rem for genetic effects
of ionizing radiation. A cumulative dose of 5 rem per
generation (or 170 mrem/yr for 30 years - the child bearing
range) might in the U.S. produce 60 - 1,000 genetically
determined illnesses of various sorts per million live
births. About 4% of live born infants or 60,000 show evidence
of hereditary defects. Thus, if this estimate is reliable,
ionizing radiation can cause a 0.1% - 1.6% increase over the
expected incidence of genetically determined illnesses. If
the same exposure level is continued for several generations,
the percentage of excess illnesses will increase due to the
presence of the malady in the parents, increasing the probabil-
ity of -it occurring in the offspring. The effect level
might eventually reach 300 - 7,500 cases per million live
births or a 0.5% - 12.5% increase.
37
-------
Of the somatic effects the most important are cancers.
The mechanism causing cancer is not known at this time.
Thus statistical data from animal and human epidemiological
studies must be used. Again little is known about the
actual effects of low dose. However by extrapolating from
high doses the death rates can be predicted as shown in
Table 5.
The estimates listed in Table 5 do not include several
variables which will change the predicted effect level. The
effect on the fetus or child is known to be higher (by
perhaps a factor of 3 - 5). The effects shown have a dif-
ferent latency period varying from 5-25 years. For exam-
ple, one would expect 1 case of leukemia/million exposed
persons/yr/rem with the approximate distribution shown in
Figure 7.
Other factors that can modify the predicted somatic
effects of low level radiation are dose rate and biological
variation. In general the effect of ionizing radiation on
the human body is cumulative. This would imply that receiv-
ing 100 rem in a day would have the same effect as receiving
1 rem per day for 100 days. This is not true at high rates
where receiving 50 rem/min for one minute is 3 times more
destructive than receiving 1 rem/min for 50 minutes. Biological
variation is due to the different sensitivity of body tissues
and the existence of some repair mechanisms in the body.
38
-------
Table 5 Expected death rates for somatic diseases.
DISEASE NUMBER OF
DEATHS/10* EXPOSED PEOPLE/YR/REM
CANCERS
LUNG 0.4-1.5
BREAST 1.5-6.0
SKELETON ai_03
Gl AND STOMACH 0.5-1.0
OVERALL 2.5
LEUKEMIA 2-4
LEUKEMIA (IN UTERO EXPOSURE) 25
39
-------
CO
<
UJ
*
D
LLJ
DC
UJ
00
5
15yr
25yr
Figure 7 Distribution of leukemias in time after the dose
40
-------
C RISK
In order to determine the importance of health effects
the associated risk must be examined . In assessing the
overall risk that the source of the radioactivity presents
to the body, the organs and the particular deleterious
effect must all be considered. The overview shown in Figure
8 relates these factors.
One way to understand the importance of the risk from
ionizing radiation is to compare it to other risks. The
determination of a standard will depend in part on this
comparison (also the resulting cost and social and political
implications have to be considered). Table 6 shows the
risks from several different causes and how they relate to
the current EPA standards for drinking water (note that the
EPA standard for Ra results in a dose to the bone surface of
150 mrem/yr, but the bone surface is less sensitive to
radiation than other tissues so that it can tolerate an
exposure rate thirty times greater than the whole body
rate).
As can be seen from Table 6, the risk from radioactivity
in drinking water (assuming that the MCL concentration was
present) is of the same order as the risk from lightning,
tornadoes and hurricanes. It is less than the risk from
natural radiation from the earth's radioactivity and solar
ultra violet radiation.
41
-------
AMOUNT OF RADIATION
FROM:
AIR
DOSE RESULTING
TO:
WHOLE
BODY
RISK
FROM:
CANCER
DRINKING
WATER
FOOD
CRITICAL
ORGANS
BLOOD
LEUKEMIA
GENETIC
EFFECTS
BACKROUND
MEDICAL
TREATMENT
SKELETAL
BONES
GROWTH
AND
DEVELOPMENTAL
EFFECTS
OCCUPATIONAL
EXPOSURE
NUCLEAR POWER
PLANTS AND
INDUSTRY
Figure 8 Overview of factors involved in determining risk from
radioactivity in drinking water.
42
-------
(14)
Table 6 Risks to people in the U.S. from various causes
The units are deaths/million people exposed/year.
DEATHS/MILLION
PEOPLE EXPOSED/YEAR
CAUSE (IN 1977)
ALL CARDIOVASCULAR DISEASE 4700
CANCER 1760
MAJOR CARDIOVASCULAR DISEASE 880
AUTOMOBILE 230
HOME ACCIDENTS 160
FALLS 66
AIR POLLUTION FROM FOSSIL FUEL POWER PLANTS 60
FIRE/BURNS 30
DROWNING 30
MELANOMA (SKIN CANCER THOUGHT TO BE DUE TO
ULTRAVIOLET RADIATION FROM THE SUN) (15) 26
POISON 26
CANCER DEATHS FROM NATURAL RADIATION (100 mrem/yr) 20
CANCER DEATHS DUE TO MEDICAL X-RAYS 16
FIREARMS 9
AIR TRAVEL 7
ELECTROCUTION 6
CANCER DEATHS FROM DOSE TO BONE OF 160 mrem/yr 1
(EPA STANDARD FOR DRINKING WATER)
ANIMAL & INSECT BITES 1
LIGHTNING 0.6
TORNADOS/HURRICANES 0.4
43
-------
The total risk due to the ingestion of 10 pCi/day of
226
Ra (or 5 pCi/l when 2 I/day is ingested) lies in the
22ft
range 0.7-3 cancers/ yr/million people exposed. Ra is
+\ *\ C.
thought to have about the same toxicity as Ra.
The only prudent approach to regulating radioactivity
is to keep the levels to all exposure as low as possible
considering health effects, feasibility and cost. Until
more information is available, the dose-response curve will
be assumed to be linear with no threshold. By adopting the
attitude that all exposures cannot be eliminated, the regu-
lator must recognize the risk and must also accept the role
Of establishing limits of exposure on the information avail-
able to him with the clear understanding that, as more
information is obtained, more research completed, greater
refinement of data accomplished, then regulatory levels may
change. Once adopted, a regulation is subjected to repeated
review and revision.
44
-------
Ill POSSIBLE CONTROL TECHNIQUES FOR RADIOACTIVITY
IN DRINKING WATER , .
If a water supply is not in compliance with the EPA
regulations for radioactivity in drinking water (see the
next section), then a number of different approaches can be
taken to deal with the problem. A more detailed discussion
of control techniques can be found in reference 16. A new
well may be drilled, and used by itself, or its water may be
blended with the more radioactive water to reduce the concen-
tration. Bottled water may be used to replace water with
high radioactivity. The primary technological methods
available for reducing the concentration of radioactivity
and ion exchange, lime softening and reverse osmosis.
There are two basic types of water softeners which
remove some inorganics. The ion exchange method is the most
common in a home. A zeolite resin is used to exchange
sodium for heavy metals (which include radium). These units
are regenerated with common table salt. Another method
(lime softening) is done on a large scale at water purification
plants, and involves adding calcium oxide or calcium hydroxide
to increase the pH to the level where the metals will precipi-
tate out. To understand how this technique works it is
useful to remember that radium is chemically similar to
calcium.
45
-------
Another technique for removing impurities in water for
small systems is reverse osmosis. Basically pressure is
used to force water through a semi-permeable membrane. The
water passes through the membrane but the impurities do not.
2
A pressure of 50 Ib/in (a normal water pressure) can achieve
90% removal of impurities. Higher pressures can achieve
higher efficiencies. Among other methods for removing
radioactivity for large systems are distillation and electro-
dialysis. The latter is similar to reverse osmosis only an
electric force is used to drive the water through a membrane.
46
-------
IV RADIATION REGULATIONS
A GENERAL
The Federal Radiation Council (FRC) in its report to
the President (1961) recommended that the upper limit
for exposure to workers in the nuclear industry be 5 rem/yr.
The upper limit for exposure to the general public was set
at 1/10 of this level while also allowing for an uncertainty
of a factor of three making the overall fraction 1/30. Thus
the upper limit for the whole body allowed dose to the
general public is:
(1/30) 5 rem/yr * 170 mrem/yr
. •'
The limits set by EPA for drinking water are 5 pCi/1 of
^ "^
Ra, 15 pCi/1 of gross alpha particle activity (excluding U
arid Rn) and a total dose equivalent of 4 mrem/yr for raan-
(18)
made radioactivity . As discussed earlier, 5 pCi/1 of Ra
produces a bone dose of 150 mrem/yr. The dose for other
alpha particle emitters (except U and Rn) is variable and is
f ' *
estimated to be no more than 1/5 of the value for Ra.
47
-------
The EPA levels (maximum contaminant levels or MCL's)
were set on the basis of the above mentioned health effects
and the removal cost of the radioisotopes . This is in
keeping with the principle that radioactivity should be
kept as low as reasonably achievable (ALARA), taking costs
into consideration.
The existing regulations covering radioactivity were
t.
promulgated July 9, 1976 in the Federal Register (Vol. 41,
No. 133, pages 28404-28409). The present discussion is
meant to provide a simplified description of the radiation
regulations, and should not be taken for legal purposes as a
replacement.
Uranium and radon are both excluded from the current
regulations but will be included in the future. Uranium was
excluded because of the additional complexity of being both
Chemically and radiologically toxic. Radon was excluded
because of its special characteristics as a gas.
Radioactivity in public water systems may be broadly
categorized as naturally occurring or from man-made sources
(such as nuclear power plants, fallout from nuclear weapons
testing and from the use of radioisotopes in scientific
laboratories, industry and medicine). Because of its
926
toxicity and occurrence Ra is the most important naturally
occurring radionuclide. Although Ra may occasionally be
found in surface waters due to man's activity, it is usually
found in ground water where it is the result of geological
48
-------
conditions. In contrast man-made radioactivity is found
primarily in surface water.
49
-------
B NATURAL RADIOACTIVITY
The determination of concentrations of natural radio-
activity begins with the measurement of the gross alpha
particle activity. The gross alpha particle activity measure-
ment is used as a screening technique. If the gross alpha
particle activity is less than 5 pCi/1, the source is in
compliance. If the gross alpha particle activity is greater
than 15 pCi/1 the maximum contaminant level (MCL) may be
exceeded. Then a decision scheme is followed as shown in
Figure 9. The MCL is exclusive of radon and uranium so
their activity should be determined, in addition, if the
gross alpha particle activity were greater than 15 pCi/1.
Uranium and radon were excluded because of uncertainties
about their occurrence, toxicity and route of exposure. In
the future MCL's for uranium and radon may well be developed.
If the gross alpha particle activity excluding radon and
uranium is less than 15 pCi/1, the source is in compliance
for gross alpha particle activity.
If the gross alpha particle activity is greater than 5
o 2fi
pCi/1, the activity of Ra must be determined. If the
O O f\.
Ra concentration is greater than 3 pCi/1, then in addition,
9 OQ" 226
the Ra activity must be determined. The total of Ra and
50
-------
MEASURE
GROSS ALPHA
IS ALPHA
> 5 pCi/l
NO
NO
i
YES
MEASURE
Ra-226
I
IS Ra-226
> 3 pCi/l
NO
YES
MEASURE
Ra-228
I
Is Ra-226
PLUS Ra-228
> 5 pCi/l
NO
YES
IS ALPHA
>15pCi/l
I
YES
MEASURE
RADON &
URANIUM
NO
I
Is ALPHA
MINUS
RADON &
URANIUM
ALPHA
>15pCi/l
I
COMPLIANCE
NON-COMPLIANC
YES
Figure 9 Flow chart for gross alpha particle activity
monitoring (U.S. EPA, Las Vegas, Environmental
Monitoring and Support Laboratory). Note that
it is not a requirement that radon and uranium
be measured if the gross alpha activity is
greater than 15 pCi/l.
-------
228
Ra must not exceed 5 pCi/1 (the MCL for radium) for the
source to be in compliance. If the supplier is not in
compliance, he must notify both the State and the public.
C MAN-MADE RADIOACTIVITY
The measurement of man-made radioactivity levels is
required for systems that serve more than 100,000 people.
This radioactivity comes primarily from fallout from nuclear
weapons testing. The screening measurement here is the
gross beta particle activity since the decay products of
fission are beta particle and gamma ray emitters. The gross
beta particle activity is used as a screening technique (See
Figure 10). If the gross beta particle activity is less
3 90
than 50 pCi/1, then tritium ( H) and strontium ( Sr) activi-
ties must be determined. These isotopes are singled out
because tritium is not included in gross beta activity since
90
it is a gas and because Sr is one of the most toxic fission
3
products. As shown in Figure 11 H must be less than 20,000
90
pCi/1 and Sr less than 8 pCi/1 for the water supply to be
in compliance. Tritium being a gas is not detected in the
gross beta screening procedure. Also, the combination of
these two must result in a dose that may not exceed 4 mrem/yr.
52
-------
YES
MEASURE
GROSS BETA
ANALYZE
TO IDENTIFY
RADIONUCLIDES,
DETERMINE
COMPLIANCE
WITH 141.16
YES
IS BETA
> 50pCi/l
NO
MEASURE
TRITIUM AND
Sr-90
IS
TRITIUM
> 20,000 pCi/l
ANNUAL DOSE
FROM
RADIONUCLIDES
FOUND IS
> 4 mrem/yr
NO
t NO
YES
IS
Sr-90
8pCi/l
YES
f NO
ANNUAL DOSE
FROM
TRITIUM Sr-90
IS ^ 4mrem /yr.
COMPLIANCE
YES
NO
NON-COMPLIANCE
Figure 10
Flow chart for gross beta particle activity monitoring
for a water source not designated as being contaminated
by effluents from nuclear facilities serving more
than 100,000 persons as designated by the State.
(U.S. EPA Las Vegas, Environmental Monitoring and
Support Laboratory)
53 .
-------
The dose level of 4 mrem/yr was chosen because it was felt that
the contributing concentrations were achievable. This dose
level is well below the 170 mrem/yr recommended by the FRC
for the general public. To determine the total dose, use
the relationship that 20/000 pCi/1 for H leads to a dose of
4 mrem/yr and that 8 pCi/1 of Sr leads to a dose of 4
mrem/yr. Thus, for example, activities of:
- 15,000 pCi/1 of H produces 3 mrem/yr
- 6 pCi/1 of Sr produces 3 mrem/yr
Thus, each individually would pass the first two tests but
combined they exceed the limit.
If the gross beta particle activity is greater than 50
pCi/1, then the water sample must be analyzed to determine
what radionuclides are present. This must be done to be
able to estimate the total dose since it is different for
each radionuclide. The doses resulting from all these
radionuclides cannot exceed 4 mrem/yr. The concentrations
of the more important isotopes that result in a dose of 4
mrem/yr are listed in Appendix III.
As an example calculation, suppose that the results of
analysis were 90Sr-2 pCi/1, 137Cs-50 pCi/1, 131Ba-60 pCi/1,
1*^1 v
and 1-1 pCi/1. Then, the resulting doses can be calculated
using Appendix III (as shown in Table 7). From Table 7, it
can be seen that the source would be just in compliance
since the total dose is less than 4 mrem/yr.
54
-------
Table 7 Example calculation of total dose for man-made
radionuclides.
CONCENTRATION CONCENTRATION IN pCI/l RESULTING INDIVIDUAL
(PCI/I) YEILDING A DOSE OF 4 mram/yr DOSE (mrem/yr)
(FROM APPENDIX III)
2 8 1.0
60 200 1.0
tt1_ 80 600 0.4
1 3 1.3
TOTAL 3.7mrem/yr
55
-------
If a supplier is not in compliance with any part of the
regulations, he must notify both the State and the public.
The State is to be notified of monitoring results 10 days
following the end of the month in which the measurement was
made unless the source is not in compliance in which case
notification must be made to the State within 48 hours.
Initially all public water supplies must sample quarterly
although only the composite need be analyzed. The results
must be analyzed by June 24, 1980 for naturally occurring
radioisotopes and by June 24, 1979 for man-made radioisotopes.
* * ^-1
.. £-«v*
After the initial sampling, each water supplier must monitor
?»)-- *'
every four years unless the State requires it to be done
more frequently. Any major change in the water supply or " ^
the addition of a new water source necessitates recompletion
of the initial sampling process.
In place of the above requirements, the State must
require further monitoring, if the water system is near a
nuclear facility. Figure 11 shows the procedure for this
analysis. The gross beta particle activity and I activity
must be measured quarterly. The gross beta particle activity
can be determined for three monthly samples or their composite.
For I, the composite of 5 consecutive daily samples shall
90
be analyzed once each quarter. Annual monitoring for Sr
o
and H is to be conducted using quarterly samples or their
composite.
-------
MONITOR QUARTERLY MONITOR
ANNUALLY
YES
YESJ"
MEASURE
GROSS BETA
1
Is BETA
> 50pCi/l
ANALYZE
TO IDENTIFY
RADIONUCLIDES,
DETERMINE
COMPLIANCE
WITH 141.16
I
ANNUAL
DOSE FROM
RADIONUCLIDES
FOUND
IS
> 4 mrem/yr
NO
COMPLIANCE
NON-
COMPLIANCE
«
Is BETA
> 15pCi/l
N9I fYES
NO
ANALYZE
FOR
Sr-89, Cs 134
*
Is Sr-89
> 80pC!/l
!
Is Cs-134
> 80pCi/l
ANNUAL
DOSE FROM
Sr-89- Cs-134
>4 mrem/yr
MEASURE
1-131
*
YES
YES
YES
Is 1-131
>3pCi/l
YES NO
COMPLIANCE
MEASURE
TRITIUM
AND Sr-90
t
Is TRITIUM
-r 20,000
pCi/l
»NO
Is
Sr-90
>8pCi/l
fNO
ANNUAL
DOSE FROM
Sr-90 H-3
>4 mrem/yr
4NO
YES
YES
YES
COMPLIANCE
NON-
COMPLIANCE
NON-
COMPLIANCE
Figure 11 Flow chart for monitoring drinking water samples
near a nuclear facility (U.S. EPA, Las Vegas,
Environmental Monitoring and Support Laboratory)
57
-------
If the gross beta particle activity exceeds 15 pCi/1
89 134
for a nuclear facility, then Sr and Cs activities are
sampled to assure that the sum of their resulting doses does
not exceed 4 mrem/yr. These isotopes indicate recent contami-
nation, such as from a nuclear facility, since they have
short enough half-lives, and are not significantly present
in fallout. Where gross beta particle activity exceeds 50
pCi/1, contributing radionuclides must be determined using
the same summing procedure as above, to determine compliance
with the 4 mrem/yr MCL.
D VARIANCES AND EXEMPTIONS
Guidance for Radium
The upper limit of the Federal Radiation Council (FRC)
Range II guide for transient rates of radium-226 ingestion
from both food and water is 20 pCi per day. Above this
range, evaluation and application of additional control
measures is always necessary (26 FR 9057, 1961). Provided
that a comparable intake of radium via the food pathway is
unlikely, exemptions for water supplies containing less than
10 pCi/1 would .be compatible with FRC guides. Occasionally,
exemptions for concentrations exceeding 10 pCi/1, for limited
times, may be acceptable.
58
-------
In granting exemptions and establishing schedules for
compliance, the primary agency should consider the extent to
which the MCL for radium-226 and radium-228 is exceeded, the
number of persons at risk, the daily intake of radium from
sources other than drinking water and the duration of time
before compliance is likely to be achieved. Since treatment
methods are readily available, compliance schedules should
provide for early installation of treatment processes or for
the use of alternative water supplies.
Guidance for Gross A.lpha
Since treatment technology exists to readily remove
substantial quantities of radium from water, only exemptions
for radium contaminants need be granted. No provision is
made for variances. Exemptions for supplies having water
concentrations of gross alpha activity up to 30 pCi/1 are
justified on the same basis as that provided for Ra-226 and
Ra-228. If a thorough analysis of the water is performed to
identify the alpha-emitting radionuclides, exemptions may be
appropriate for limited time periods if the dose to bone
from all alpha particle emitters, including Ra-226, is less
than 300 mrem per year even though the gross alpha activity
exceeds 30 pCi/1.
59
-------
Guidance for Man Made Beta and Photon Emitters
Neither variance or exemptions should be necessary
except in cases of malpractice. In cases where a water
supply has been contaminated via chronic or intermittent
releases, a variance or exemption may be necessary for a
limited period of time to insure an uninterrupted supply of
water for drinking and other purposes.
Current federal guidance for transient rate of intake
provides limitations on food and water intake that are
comparable to an annual dose equivalent of 50 mrem/year and
contain a recommendation that for transient situations the
dose should be averaged over one year (26 FR 9057). The
variance and exemption limitation shall not exceed 50 mrem/year
to any organ from radioactivity in finished drinking water
(12 times EPA's 4 mrem/year standard). The maximum dose
commitment for any one day from radioactivity in drinking
water shall not exceed 10 mrem.
60
-------
REFERENCES
(1) Natural Background Radiation in the United States,
1976, National Council on Radiation Protection and
Measurements, (NCRP) Publication #45, Washington,
D.C. 20014.
(2) J. Shapiro and D. W. Moeller. 1978. Population
Exposures from Radionuclides in Medicine — As Low
As Reasonably Achievable? Am J. Public Health.
68:219-220.
(3) Adler, H. I. and A. M. Weinberg. 1978. An Approach
to Setting Radiation Standards, Health Physics.
34:719-720.
(4) Schleien, B., G. D. Schmidt and R. P. Chiacchierini.
1979. Application of the Dose Limitation System
for Radiation Protection. International Atomic
Energy Agency, Vienna. Publication IAEA-SR 36/24,
pages 613-623.
(5) T. Whiteside. The Pendulum and the Toxic Cloud,
The Course of Dioxin Contamination. 1979. Yale
University Press.
(6) Dixon, R. L. 1976. Problems in Extrapolating
Toxicity for Laboratory Animals to Man. Environ-
mental Health Perspectives. 13:43-50, and R. L.
Dedrick. 1973. Animal Scale-Up. J. Pharmacokinetics
and Biopharmaceutics. 1:435-461.
(7) Dolphin, G. W. and I. S. Eve. 1966. Dosimetry of
the Gastrointestinal Tract. Health Physics.
12:163-172.
(8) Task Group on Lung Dynamics. 1966. Deposition
and Retention Models for Internal Dosimetry of the
Human Respiratory Tract. Health Physics. 12:173-
207.
(9) ICRP Publication 30, 1979. Limits for Intakes of
Radionuclides by Workers, Volume 2, No. 3/4.
International Commission on Radiological Protection.
Pergamon Press.
(10) National Interim Primary Drinking Water Regulations.
EPA-570/9-76-003.
61
-------
(11) ICRP Publication 26, 1977. Recommendations of the
International Commission on Radiological Protection.
Volume 1, No. 3, Pergamon Press.
(12) For the health effects of ionizing radiation see for
example:
-Known Effects of Low-Level Radiation
Exposure. April 1980. U.S. Department
of Health, Education, and Welfare,
Public Health Service, National Institutes
of Health, NIH Publication No. 80-2087.
-The Effects on Populations of Exposure
to Low Levels of Ionizing Radiation.
1972. Report of the Advisory Committee
on Biological Effects of Ionizing Radiations
(BIER), National Academy of Sciences,
Washington, D.C. 20006.
-Drinking Water and Health, Safe Drinking
Water Committee. 1977. National Academy
of Sciences, Washington, D.C. 20006.
-Interagency Task Force on Ionizing
Radiation. Feb. 27, 1979. U.S. Department
of Health, Education and Welfare (Labassi
Report).
-Casarett, A.P., 1968. Radiation Biology,
Prentice-Hall, Inc., Englewood Cliffs, New Jersey.
(13) Lowrance, W. W. 1976. Of Acceptable Risk, William
Kaufman Inc., Los Altos, California.
(14) Accident Facts. 1978. National Safety Council and W.
D. Rowe. An Anatomy of Risk. 1977. John Wiley and
Sons.
(15) Protection Against Depletion of Stratospheric Ozone by
Chlorofluorocarbons. 1979. Committees on Impacts of
Stratospheric Changes, Alternatives for the Reduction
of Chlorofluorocarbon Emissions and Socialtechnical
Systems, National Academy of Sciences, Washington,
D.C. 20006^
(16) Costs of Radium Removal From Potable Water Supplies,
USEPA, EPA-600/2-77-073, April 1977, and Manual of
Treatment Techniques for Meeting the Interim Primary
Drinking.Water Regulations, USEPA, EPA-600/8-77-005.
April 1978.
62
-------
(17) Background Material for the Development of
Radiation Protection Standards, Staff Report of
the Federal Radiation Council, Report No. 2. September 1961
(18) Federal Register, Vol. 41, No. 133, pages 28404-28409.
July 9, 1976.
63
-------
GLOSSARY
Alpha Particle - a helium nucleus, two protons and two
4
neutrons, He*
Atomic Mass Number - the total number of protons and neutrons
in the atomic nucleus.
Atomic Number - the number of protons in the nucleus,
identifies the element.
Beta Particle - an electron ejected from the atomic nucleus.
Curie - activity of one gram of radium or 3.7 x 10
disintegrations/second.
Fission - process where a heavy nucleus splits into two
roughly equal fragments, a few neutrons and releases a
large amount of energy.
Gamma Ray - form of electromagnetic radiation emitted
' in nuclear decay.
Genetic\Effect - a health effect that shows up in subsequent
generations.
64 .
-------
Half-Life:
Radioactive - time for one-half of the isotope to
decay.
Biological - time for one-half of the atoms to move
from that organ.
Ionizing Radiation - radiation that is capable of ionizing
or removing one or more electrons from an atom.
Isotope - varieties of the same element with different
masses (different neutron numbers).
Mutagen - substance that can change the structure of DNA and
thus change the basic blueprint for cell replication.
Natural Radioactive Series - sequence of elements that
exist naturally and decay into each other in a serial
fashion.
Quality Factor - a factor that roughly approximates the
relative differential damage that ionizing radiation
can do to tissue.
Radioactive Decay - a process where the nucleus transforms
to a lower energy state by emitting alpha, beta or
\
gamma radiations.
-------
Rad - amount of ionizing radiation that deposits 100 ergs
of energy in one gram of tissue.
Rem - the number of rads times the quality factor — a
quantity that is more descriptive of the actual damage
to tissue from ionizing radiation — Radiation
Equivalent Man.
Somatic Effect - health effect to the body exposed — for
ionizing radiation, mainly cancers and Leukeraias.
Teratogenic Effect - health effect to the fetus.
66
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APPENDICES
I CHEMICAL ELEMENT SYMBOLS AND ATOMIC NUMBERS
II NATURALLY OCCURRING RADIOACTIVE SERIES
III CONCENTRATIONS YIELDING 4 mrem/yr DOSE
67
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APPENDIX I
Chemical element symbols and atomic numbers
Actinium
Aluminum
Americium
Antimony
Argon
Arsenic
Astatine
Barium
Berkelium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Californium
Carbon
Cerium
Cesium
Chlorine
Chromium
Cobalt
Copper
Curium
Dysprosium
Einsteinium
Erbium
Europium
Fermium
Fluorine
Francium
Gadolinium
Gallium
Germanium
Gold
Hafnium
Helium
Holmium
Hydrogen
Indium
Iodine
Indium
Iron
Krypton
Lanthanium
Lawrencjum
• Lead
Lithium
Lutetium
Magnesium
Manganese
Mendelevium
Symbol
Ac
Al
Am
Sb
Ar
As
At
Ba
Bk
Be
Bi
B
Br
Cd
Ca
Cf
c
Ce
Cs
Cl
Cr
Co
Cu
Cm
Dy
Es
Er
Eu
Fm
F
Fr
Gd
Ga
Ge
Au
Hf
He
Ho
H
In
I
Ir
Fe
Kr
La
Lr
Pb
Li
Lu
Mg
Mr,
Md
Atomic
Number
89
13
95
51
18
33
85
56
97
4
83
5
35
48
20
98
6
58
55
17
24
27
29
96
66
99
68
63
100
9
87
64
31
32
79
72
2
67
1
49
53
77
26
36
57
103
82
3
71
12
25
101
Mercury
Molybdenum
Neodymium
Neon
Neptunium
Nickel
Niobium
Nitrogen
Nobelium
Osmium
Oxygen
Palladium
Phosphorus
Platinum
Plutonium
Polonium
Potassium
Praseodymium
Promethium
Protactinium
Radium
Radon
Rhenium
Rhodium
Rubidium
Rutheium
Samarium
Scandium
Selenium
Silicon
Silver
Sodium
Strontium
Sulfur
Tantalum
Technetium
Tellurium
Terbium
Thallium
Thorium
Thulium
Tin
Titanium
Tungsten
Uranium
Vanadium
Xenon
Ytterbium
Yttrium
Zinc
Zirconium
Symbol
Hg
Mo
Nd
Ne
Np
Ni
Nb
N
No
Os
O
Pd
P
Pt
Pu
Po
K
Pr
Pm
Pa
Ra
Rn
Re
Rh
Rb
Ru
Sm
Sc
Se
Si
Ag
Na
Sr
S
Ta
Tc
Te
Tb
Tl
Th
Tm
Sn
Ti
W
U
V
Xe
Yb
Y
Zn
Zr
Atomic
Number
80
42
60
10
93
28
41
7
102
76
8
46
15
78
94
84
19
59
61
91
88
86
75
45
37
44
62
21
34
14
47
11
38
16
73
43
52
65
81
90
69
50
22
74
92
23
54
70
39
30
40
-------
THE URANIUM SERIES
69
-------
THE THORIUM SERIES
232Th
90
1.4x1010yr
212Po
84
3.0x10'6sec
70-
-------
THE ACTINIUM SERIES
-------
APPENDIX III
Annual Average Concentrations Yielding 4 Millirem per Year for a Two Liter Daily Intake,
From National Interim Primary Drinking Water Regulations, EPA- 570/9 - 76-003
Radionuclide
Tritium
"Be7
6C14
]]Na22
"Na24
15p32
J6S35
"CP«
19K42
2<>Ca45
20 Ca47
21Sc«
21 Sc47
21SC4*
23y48
24O-51
25Mn«
25Mn54
26Fe55
26pe59
27 COST
27 Co 58
27 CO60
28NJ59
28NJ63
30Zn«
32Ge"
33 AS"
33 AS'4
33 AS76
33 AS77
34 Se"
35Br82
37Rb86
37Rb87
38 Sr 85
38SI-89
38Sr8«
38 Sr90
39Y90
39Y91
40Zr»
40Zr»5
41Nb'3n>
41 Nb95
42 MO »9 •
• 43Tc««
43Tc97m
43 Tc'7
43 Tc"
44RU97
44RU103
44RU106
45RH105
46Pdl03
46PJI09
Critical Organ
Total Body
GI (LLI)
Fat
Total Body
GI(S)
Bone
Testis
Total Body
GI(S)
Bone
Bone
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
Spleen
GI (LLI)
GI (LLI)
GI(LLI)
GI (LLI)
Bone
Bone
Liver
GI (LLI)
GI (LLI)
Gi (LLI)
GI (LLI)
GI (LLI)
Kidney
GI (LLI)
Total Body
Pancreas
GI (SI)
Bone
Bone Marrow (FRC)
Bone Marrow (FRC)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
Kidney
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
C4
(pCi/1)
20,000
6,000
2,000
400
600
30
500
700
900
10
80
1,000
300
80
90
6,000
90
300
2,000
200
1,000
300
100
300
50
300
6,000
1,000
100
60
200
900
ICO
600
300
21,000
20
80
8
60
90
2,000
200
1,000
300
600
300
1,000
6,000
900
1,000
200
30
300
900
300
-------
47Agl05
47AgHO
47Aglll
48 Cd115"
48Cd»5
51 Sb122
si Sb124
5tSb'«
52 Te127
52Te 129
52Te>31m
53] 125
531 126
53 1 129
53J131
55CS134
55CS135
55Cs'37
5«Bai«o
57Lal40
58Ce'«3
56prl43
<3£U154
6«Dy16«
67Hol»«
68£r169
69Tm"i
71 Lu177
73 Ta182
74 ^V 181
74 W185
75 Re 183
75R8I86.
75 Re 187
76QS185
76Qsl93
GI (LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI (LLI)
Kidney
Kidney
GI(LLI)
Gl(LLI)
GI(S)
GI(LLI)
GI(LLI)
Thyroid
Thyroid
Thyroid
Thyroid
Total Body
Total Body
Total Body
Total Body
Total Body
GI(LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI (LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI (LLI)
GI (LLI)
GI(LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI (LLI)
300
90
100
600
90
90
300
300
60
90
60
300
600
200
900
90
2,000
200
90
3
3
1
3
20,000
80
900
800
200
600
90
60
300
100
100
100
1,000
200
60
200
600
600
100
100
90
300
100
1,000
300
300
200
100
1,000
300
2,000
300
9,000
200
600
200
600
-------
77 If 192
78ptl9l
78ptl93
78ptl93
79AU196
79All"8
80Hgl97
80Hg203
81J1204
83BJ206
83B1207
9Ipa233
GI(LLI)
GI(LLI)
GI(LLI)
Kidney
GI (LLI)
GI (LLI)
GI (LLI)
Kidney
Kidney
GI(LLI)
GI(LLI)
GI (LLI)
GI(LLI)
GI(LLI)
100
300
3,000
3,000
300
600
100
900
60
300
1,000
100
200
300
(Half-life less than 24 hours)
Radionuclide
9pl8
14SJ31
17Q38
19R«
25Mn«
27 Co 5* m
28Ni«
29 Cu64
30Zn"m
30Zn'9
siGa"
38Sr85m
38Sr91
3«Sr92
39Y91™
39 Y 92
39Y93
40 Zr"
41Nb97
43Tc'«m
43Tc99m
44RK105
45Rhl03m
49Inll3m
49Inll4m
49In"5m
53J 132
331 133
53J 13*
53J135
55Cs'34m
59pr142
60Nd'«
,63Eu'52
64 Gd159
66Dyl65
68 £r l?l
74W187
75 Re 188
76Os'*t\1
77 IT I'*
78Ptl97m
81T1202
Critical Organ
GI (SI)
GI(S)
GI(S)
GI(S)
GI(LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI (LLI)
GI(S)
GI(LLI)
Total Body
GI (LLI)
GI(ULI)
GI(SI)
GI(ULI)
GI(LLI)
GI(LLI)
GI(ULI)
GI(LLI)
GI(ULI)
GI(ULI)
GI(S)
GI (ULI)
GI (LLI)
GI (ULI)
Thyroid
Thyroid
Thyroid
Thyroid
GI(S)
GI(LLI)
GI (LLI)
GI (LLI)
GI (LLI)
GI(LLI)
GI (ULI)
GI(LLI)
GI(LLI)
GI(LLI)
GI(LLI)
GI(ULI)
GI (LLI)
C4
ocw;
2,000
3,000
1,000
900
300
9,000
300
900
200
6,000
100
900
200
200
9,000
200
90
60
3,000
30,000
20,000
300
30,000
3,000
60
1,000
90
10
100
30
20,000
90
900
200
200
1,000
300
200
200
9,000
90
3,000
300
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA 370/9-81-002
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
January 1981
Radioactivity in Drinking Water
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
C. Richard Cothern
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
r t. n r \s n IVM IN o v_/n vj r-\i'i 11/-\ i IVJIN ii^ivit ^AI«« i_/ /^ L> L-* n cjo
Health Effects Branch/Criteria & Standards Division
Office of Drinking Water
Environmental Protection Agency
Washington, D.C. 20460
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This general overview is designed to assist those involved with public health and
drinking water to better understand, interprete and implement EPA's regulation
for radioactivity in drinking water. In this presentation the general nuclear pro-
perties are shown by using naturally occurring isotopes such as radium, radon and
uranium as examples. The units of radioactivity (curie, rad, ran) are explained and
demonstrated in describing natural radiation in our surroundings and bodies as well
as man-made radiation from medical x-rays, TV, fall out, industrial uses and nun]ear
power plants and other sources. The health effects discussed include birth defects,
genetic damage, cancers, leukemias and others. Several specific examples are given
in each disease area as well as their relative importance or rate of occurrence.
The risk (in deaths/million people exposed/yr) is tabulated for radioactivity and
compared to several other cases including disease, accidents and weather. Possible
methods for reducing the radioactivity in drinking water are described. Flow charts
provided that show how to interpret measurements of radioactivity in drinking water
and what additional measurements may be required.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Radioactivity, Drinking Water, Health
Effects, Regulations
18. DISTRIBUTION STATEMENT
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76
20. SECURITY CLASS (Thispage)
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