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LIBRARY

AUGg8 1962

II. J. »««we: * in/w.ii«

BEl.TSViLlL BRANCH

PROTECTION OF

AGAINST

NUCLEAR ATTACK

guide for agricultural leaders

AgTicOlture Handbook No. 234

AGRICULTURAL RESEARCH SERVICE • U.S. DEPARTMENT OF AGRICULTURE
PROTECTION OF

3 guide for agricultural leaders

Agriculture Handbook No. 234

AGRICULTURAL RESEARCH SERVICE " U.S. DEPARTMENT OF AGRICULTURE

Washington, D.C. 1962

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington 25, D.C. - Price 30 cents
PREFACE

If a nuclear attack were to be made upon the United States, all segments of

our population and of our economic structure would be affected. Many of the

problems created would be similar if not identical among the various segments.

Some of the effects would be peculiar to each segment according to its needs and

responsibilities.

Thus, agriculture would share the Nation's total difficulty and still be

faced with special problems. The United States Department of Agriculture,

in cooperation with other agencies of Federal and State governments, is responsible for helping to develop means by which farm people could cope with these

special problems for their own protection and to maintain farm production

in times of emergency. In fulfilling its responsibility, the Department participates in devising active defense and implementing actual protective programs,

in conducting research to provide the knowledge on which these programs are

based, and in keeping farm people and agricultural leaders informed about

them.

One of the major parts of the defense plan being developed against nuclear

warfare is aimed at reducing potential hazards from radioactive fallout. This

handbook describes what is known about the effects of fallout on agriculture

and what defensive measures can be taken against them. The infonnation,

including tables and denial times, is based on emergency conditions, not those

prevailing in times of peace.

Some of the terms used may be unfamiliar because the widespread application of nuclear science is relatively new. However, many of them are rapidly

becoming a part of the Nation's everyday vocabulary. A glossary is included

in this publication to aid in a fuller understanding of such terms.

Ill
CONTENTS

Page

Nuclear Explosion 1

Area of Destruction 1

Fallout Formation 2

Area of Severe Fallout—Surface Detonations 2

Residual Eadiation and Fallout 2

Radioactivity Not Transferred From

Fallout 3

Gamma and Beta Radiation 4

Radiation Hazards From External and

Internal Sources 4

Protection Against External Radiation

From Fallout 5

Effect of Distance 5

Effect of Time on Intensity of Radiation _ 5

Effect of Shelter and Shielding 6

Shelter 6

Radiation Attenuation 7

Decontamination 8

Work Schedules in Fallout Areas 9

Handling Livestock 10

Poultry 11

Shelter 12

Irradiation Effects on Animals 13

General 13

Sexual and Genetic Effects 13

Embryologie Effects 13

Protection Against Internal Radiation From

Fallout 13

Radioisotopes Causing Internal Radiation 13

Protection of Food, Feed, and Water__ 15

Food 15

Feed and Water 16

Radioactive Iodine and Radioactive

Strontium in Food 17

Radioactive Iodine 17

Reducing Iodine 131 Contamination

of Food and Dairy Products 18

Page

Protection Against Internal Radiation

From Fallout—Continued

Radioactive Iodine, etc., in Food—Con.

Radioactive Strontium 19

Radioactive Strontium in Food 19

Croplands Contaminated by Fallout 21

Use of Contaminated Land 21

Reducing Strontium 90 Uptake With

Soil Amendments 23

Croplands Contaminated by Irrigation

Water 23

Reclaiming Contaminated Land 24

Decontamination by Removal of

Ground Cover and Crops 25

Decontamination by Removal of Surface Soil 25

Other Methods of Decontaminating

Soil 25

Reclaiming Soil by Deep Plowing 25

Effects of Radiation on Plants and

Seeds 26

Summary of Effects of Fallout on Agriculture 26

Shelter 26

Food, Feed, and Water 26

Maximum Work Times 26

Food Decontamination 26

Reclaiming the Soil 26

Glossary 27

Appendix A—Measurement of Fallout

Radiation 30

Appendix B—Protection Factors 34

Appendix C—40 Cow Dairy Barn and

Family Fallout Shelter 36

Trench-Type Shelter Arrangements 37

(A, B, C, D) Roofs for Trench-Type

Fallout Shelters 37

(E, F) Fallout Protection in Buildings_. 37

Publications and Films 40

IV
PROTECTION OF

FOOD AND AGRICULTURE

AGAINST

NUCLEAR AHACK

A guide for agricultural leaders

The development of nuclear energy has created

a new and uncertain element in man's world. On

the one hand are the rapidly expanding liorizons

of progress made possible through the peacetime

uses of this new form of energy. On the other

hand is the possibility of damage or destruction

of man and his possessions through the use of nuclear weapons if world peace cannot be maintained.

One of the important defenses against widespread destruction from nuclear weapons is a wellinformed population, armed with as much knowledge as possible about protection and survival in

case of attack. Agricultural leaders and farmers

are responsible now, in time of peace, for developing a capability of the Nation to protect its people

and the ability to produce food and other products

necessary for existence.

Researchers are developing knowledge that will

help to provide this protection and those in the

U.S. Department of Agriculture are taking part.

The study of nuclear weapons is relatively new

and the usual techniques of research cannot always be applied because of obvious restrictions

on the conditions of testing nuclear weapons. Itis

therefore understandable that not all of the

needed information in this field is fully developed

today. However, studies are extensive and the

fund of knowledge is growing.

One of the problems that is being widely studied

to help agriculture survive a nuclear attack is the

effects of radioactive fallout and what can be done

to preA'ent or minimize them. In approaching this

problem, we can start with a brief description of

the nuclear explosion itself.

NUCLEAR EXPLOSION

A nuclear explosion results in four destructive

phenomena: (1) Blast, (2) light and heat radiation, (3) initial ionizing radiation, and (4) residual ionizing radiation. The first three are almost

instantaneous at the moment of detonation, butthe

fourth (residual radiation, especially from detonations on the ground) produces its effects later,

longer, and over a wider area, as fallout.

Area of Destruction

The area of destruction resulting from the blast,

heat, and initial radiation will vary with the size

of the weapon, the height of the explosion, and

to some extent with the terrain and atmospheric

conditions atthe time of the explosion.

The size of the weapon is measured in terms of

its total energy release compared with the energy

released by TXT (trinitrotoluene, a nonnuclear

explosive) when it explodes. For example, a 1-

kiloton nuclear bomb produces the same amount

of energy as the explosion of 1 kiloton (or 1,000

tons) of TNT. A 1-megaton bomb has the energy

equivalent of 1 million tons (or 1,000 kilotons) of

TNT. The earliest nuclear weapons released

roughly the same quantity of energy as 20,000 tons

(or 20 kilotons) of TNT. The energy release of

the large bombs developed since World War II

ranges from kilotons to many megatons.

Field tests have indicated that a 5-megaton nuclear bomb exploded on the surface of the earth

would cause severe destruction to residential buildings out to about 6 miles from the point of detonation. Similar destruction from a 20 megaton device would extend out almost 10 miles. The heat

from an 8-megaton bomb exploded on the earth's

surface might set fires to easily ignitable materials

during the first few seconds after detonation out

to about 25 miles on a clear day. If it were exploded 2 to 3 miles above the surface of the earth,

its heat would cause fires at somewhat greater

distances.

In general, the height of the explosion can be

considered in one of three classifications: (1) Air

bursts, (2) surface bursts, and (3) subsurface

bursts, the last one consisting of underwater and

underground bursts. Obviously, whether the blast
occurs hipfli in the air, at or near the surface of

the fjround or water, underjiround, or underwater

affects the area of damage.

Elements of the terrain such as mountains and

hills also affect the blast and fire damage area.

^.^^ example, a $v.T-fnr.o o^plpoi^r, c„T^^„x^ed by

nigh hills or mountains might damage a more lii""

ited area than one on a broad flat iilain. Wmd

direction or velocity and rain also influence the

extent of fire damage.

Fallout Formation

"\^nien a nuclear explosion occurs close to the

ground and the fireball touches the surface, large

quantities of earth are vaporized or melted by the

intense heat of the fireball, and thousands of tons

of earth are pulverized by the blast. As the fireball rapidly rises, the ascending currents of air

carry much of the pulverized earth upward into

the fireball and the developing mushroom cloud,

where some of the particles are vaporized, some

are liquefied, and others remain in the solid state.

Part of the vaporized radioactive residue of the

weapon condenses in or on the liquefied or solid

particles of earth. These particles thus become

sources of radiation.

According to estimates, about one-half of the

material from a surface nuclear detonation will

return to the earth's surface as fallout within 16

hours. In about 24 lioure most of this local fallout, M'hich accoimts for approximately 80 percent

of the total radioactive debris, will have settled.

The remaining 20 percent of the radioactive material goes high into the troposphere or passes

through the tropopause into the stratosphere.

When a high-yield nuclear device (megaton) is

detonated, the radioactive products resulting

therefrom move through the troposphere, the

tropopause, and end largely in the stratosphere.

In case of an aerial burst, the fraction of the radioactive products that enters the stratosphere

will be larger than that from a surface burst.

Some radioactive materials are scattered on the

ground locally and some are left at various altitudes as the atomic cloud ascends. The bulk of

the radioactive fission products, however, are

thrust into the stratosphere where they become

dispersed in the stratosphere with a greater concentration in the hemisphere in which the device

was detonated.

The atomic material in the stratosphere follows

the winds at this extremely high altitude and

travels around the world until it finally descends.

The return of this radioactive material to the

earth is rather slow, carried principally by rain

descending into the troposphere.

The residence time in the upper atmosphere

ranges from months to several years. Because of

this long residence time, the radioactive fallout

would contain mostly the long-lived isotopes.

The radioactive fallout is composed of long-life,

medium-life, and short-life isotopes.

When the smaller atomic devices are exploded,

the radioactive materials remain in the upper area

of the troposphere. The residence time of radioactive fission particles at this level is measured in

weeks or months. The pattern of distribution is

not world-wide but largely confined to the hemisphere in M-hich it originates, generally following

the wind patterns passing through the point of

origin.

Area of Severe Fallout—Surface Detonations

Of the fallout that reaches the earth's surface

m the first 24 hours, the greater portion is in the

general vicinity of ground zero (point of the

earth's surface directly under the detonation).

It extends from this point to possibly as far as

1,000 miles or more downwind, the distance depending upon wind speed. This downwind direction may differ by as much as 180 degrees from

the direction of the surface wind and may carry

the debris at speeds of 75 miles or more per hour.

The initial height of the particles, their size,

shape, and density, together witli the upper air

winds and precipitation, will largely determine

when and where they will reach the earth's surface. This fallout is a source of radiation that

can be hazardous to man and animals in the area

where it reaches the earth's surface.

It takes time for fallout to drop from the radioactive cloud, even close to the burst. The earliest

arrival time outside the totally devastated area

might be nearly 30 minutes after detonation. Some

areas within the pattern of severe contamination

might not get the fallout for as long as 24 hours

after the explosion. At any particular location it

could continue to fall for hours.

RESIDUAL RADIATION AND FALLOUT

About 90 percent of tlie energy of a nuclear

explosion is released through the blast, light and

heat, and initial radiation. The remainino-10 percent of the bomb's energy is expelled asl-esidual

radiation in fallout. Arbitrarily, residual radiation is said to begin about 1 minute after the explosion. It continues at a diminishing rate for

years.
Tallout

FiGüEE 1.—In a nuclear explosion thousands of tons of material are taken up into the fireball. As the fireball cools,

radioactive particles formed from the bomb are fused with particles of dirt and debris to form radioactive fallout.

Where it falls to earth depends, in part, on the place of origin, on the size of the particles, and on the direction

and velocity of the wind.

Eadiation is emitted by radioisotopes (fission

products, and radioisotopes formed by neutron

capture) produced by the explosion of the bomb.

It can pass into and through matter. Radiation

can change, damage, or destroy living c«lls through

ionization (see glossary) of cell constituents.

Since fallout contains radioactive fission products and other isotopes, it emits nuclear radiation.

The fission products condense in and on dust and

soil particles. Physically it behaves like dust or

soil falling onto exposed surfaces. Sometimes, in

areas of heavy fallout, it is visible and to the unaided eye may resemble dust such as that from a

cultivated field, as a fine white powder, or tiny

glassy beads.

Fallout composition varies with the type of soil

or rock at ground zero, but fallout generally takes

the form of granular sand, glassy beads, or dust,

and is readily distinguished on smooth or polished

surfaces, if present in significant amounts. The

intensity of radiation from the fallout produced

by a. given explosion varies roughly with the

amount of the fallout.

Radioactivity Not Transferred From Fallout

Radiation from fallout does not cause irradiated matter, living or inanimate, to become radioactive itself. In considering the effect of fallout

on agriculture, the radioactive contamination in

the fallout itself is the principal concern.

Fallout as a source of radiation can be compared

to a lantern as a source of light rays. T^Hien the

lantern is in a room, it emits light rays that strike

various objects. When the lantern is removed,

the light rays are gone and the room is dark. In

the same way, when it has been possible to remove
the fallout, the radiation is gone and the irradiated

materials are not radioactive. However, the radiation damage to the-trving matter may pei^^ '

although its effect may not appear until later.

Gamma and Beta Radiation

Gamma rays and beta rays are the two most

important types of radiation in fallout. Gamma

rays are similar to X-rays. Their danger in fallout is greatest soon añer it arrives in an area.

The rays can travel long distances (many feet

through air and several feet through water) and

are difficult to shield against. The intensity of

the gamma rays can be reduced only by shielding

with a sufficient mass of material between the

source of radiation and the subject. In general,

the denser the material the lesser is the thickness

required for shielding against gamnia rays.

Beta "rays'' are particles identical with high

speed electrons. Beta particles can be easily

stopped. Several layers of clothing can aid in

protecting against penetration of beta particles.

However, if a sufficient quantity of fallout gets

on bare skin, beta particles will cause severe burns,

and the effects may be even more serious if sufficient fallout is ingested or inhaled by man or livestock. Some of these isotopes continue to emit

beta particles for long periods of time—measured

in years.

See Appendix A for information concerning

special instruments developed for the detection

and measurement of various nuclear radiations.

Radiation Hazards From External and Internal Sources

The hazards of ionizing radiation from fallout

to living organisms arise generally from two

sources: (1) External sources and (2) internal

sources. Both are of concern to agriculture : First,

as a potential hazard to farm people and their

livestock, including poultry, and second, as a

source of danger to the consmners of agricultural

food products.

(1) Radiation from external sources is a severe problem that would be faced during the first

few hours or days following the arrival of the

fresh fallout on the surface of the land. The

gamma radiation for a time soon after the arrival

of early fallout is more hazardous than beta radiation, since it is effective at greater distances from

the source and is more difficult to shield against.

As radiation intensity declines, the beta radiation

from particles in contact with tissue becomes relatively more significant. The effects of the radiation on man and animals can range from nondetectable damage through varying degrees of

"radiation sickness" to death. Also, radiation

sickness can block the ability of normal body

mechanisms to fight or overcome infections.

The amount of radiation that will damage a

living body depends upon the number and type of

cells affected and the type of tissue or organ

affected. If the radiation damages the cell to the

extent that its ability to function and reproduce

itself is lost, and if enough cells are thus damaged

so that it is difficult for surrounding tissues to

repair or replace the damaged cells, the injury is

severe and in the extreme situation may be fatal.

The human body has recovery processes that are

capable of repairing a major portion of the radiation injury, except where the dose is so great that

death occurs within a few days or weeks after the

onset of exposure. Because of the existence of

these recovery processes, individuals are able to

survive exposure to larger amounts of radiation

when the exposure is distributed over long periods

of time. The concept of the equivalent residual

dose (ERD), which takes into consideration the

recovery processes, is used to allow for differences

in biological effects of exposures between those

delivered during very short and those delivered

during longer periods of time. '\'\Tien exposure

occurs over a few days or less, the total accumulated dose and the ERD will be essentially the

same. However, when exposure to radiation is

spread somewhat evenly over months or years,

the total accumulated dose may be as much as five

times that of the ERD. The ERD is the controlling factor.

In evaluating the effect of damage from radiation exposure, biologists estimate that 10 percent

of the exposure is irreparable and that the body

can repair about one-half of the remaining 90

percent in a month. The other 45 percent can be

assumed to be repaired after about 3 additional

months. Therefore, the ERD at any time is equal

to 10 percent of the accumulated dose (the irreparable fraction of injury) plus the fraction of

the balance of the accumulated dose that has not

yet been repaired. It is assumed that recovery

commences about 4 days after the onset of exposure and that each day there is repair of about

2.5 percent of the then remaining reparable damage. This rate of recovery may reduce the reparable damage to about zero by the end of 4 months'

postexposure.

For example, if a normal healthy adult receivea

a dose of 200 roentgens (see glossary) during the

first few days of the month, his ERD early in

the month would be approximately 200 roentgens.

Of this amount, 10 percent or 20 roentgens would

be irreparable and 180 roentgens would be reparable. During 1 month, half of this latter

amount, or about 90 roentgens, would be repaired.

Therefore, provided additional exposure could be
avoided, the individual's ERD at the end of 1

month would be 90 roentgens plus 20 roentgens,

or 110 roentgens. In this case an exposure of an

additional 90 roentgens, if required during the

succeeding month, probably would not incapacitate the individual to an extent requiring medical

attention.

All but the most important farm operations

should be postponed as long as feasible in order to take full advantage of the decay of the

radioactivity.

(2) Radiation from internal sources may be a

serious and long-lasting problem created chiefly

by the consumption of contaminated food and

water and the inhalation of contaminated air.

It is caused chiefly by the isotopes that produce

beta rays which are capable of traveling only

short distances in the body, or gamma rays which

can travel throughout the body, or both. While

inside the body the isotopes continue to emit radiation which damages the surrounding cells.

Most food commodities, both plant and animal,

can be contaminated with fallout materials and

thus can be an internal source of radiation for

consumers. Much study is being given to this

phase of radiation hazard.

AH defense efforts or protective measures

against radiation or radioactive fallout are directed at either preventing harmful ionization

within living cells or minimizing the radiation

exposure and efi^ects of ionization.

The principal protective measure for man and

animals against the external hazard is the maximum use of shielding or shelter, allowing time

for the decrease of radiation intensities.

Protection against the internal hazard includes

all measures to protect food, feed, and water for

man and animals from radioactive contamination ;

to keep the radioactive materials outside the

body. One radiological defense objective, therefore, is to attempt to prevent contamination where

possible or, if this cannot be accomplished, to

minimize the amount of contamination of the food

supply.

Researchers have developed information on protection against both external and internal radiation hazards of fallout. The remainder of this

publication deals with methods of protection for

agriculture, farm families, and consumers of

agricultural products.

PROTECTION AGAINST EXTERNAL RADIATION

FROM FALLOUT

Radioactive fallout would have serious efl^ects

upon agriculture and food production and storage

in the event of attack with nuclear weapons, bur

there are practical methods of protection. The

four basic elements of protection against external

radiation from fallout are distance, time, sliielding, and decontamination.

Effect of Distance

Distance is a natural protection against fallout

radiation from external sources. As would be

expected, the radiation exposure is less the farther

away you are from the source of radiation. Thus,

fallout on a roof 20 feet over your head will give

less radiation exposure than the same amount of

fallout on the same roof 5 feet over your head.

This is true because the radiation is reduced in

intensity as it moves away from the point of

origin.

Effect of Time on Intensity of Radiation

The lapse of time after a nuclear explosion is

also a natural protection against the external radiation hazard from fallout because of the decay factor of radioactivity. The longer it takes the fallout to reach an area, the greater is the time

required for radiation intensity to decrease because of decay.

About 200 different isotopes of nearly 35 elements have been identified among fission products

created by nuclear explosions. The radioactivity

of each isotope diminishes or "decays" at a specific

rate, different for each isotope. Usually the rate

of decay is expressed in terms of the ''half-life"

of the isotope. Some isotopes lose half their radioactivity within seconds after the explosion.

Others take days or months or years to lose half

their radioactivity. For example, iodine 131 has

a half-life of 8 days. Thus, iodine 131 has decayed

to half its original activity in 8 days, half the

remainder is gone in another 8 days, and so on.

After 54 days, only 1 percent of the radioactivity

will remain. Strontium 90 has a half-life of 28

years and 1 percent of its radioactivity will remain

after 180 years.

The total radiation hazard of newly formed

(fresh) fallout decreases rapidly at first because

it contains many radioisotopes with short halflives. The radiation hazard decreases more

slowly after the shorter lived elements have lost

most of their radioactivity.

In order to estimate the rate of decrease of total

radioactivity, an approximate rule may be used.

644700 O—62
Time - Decay

t^ l\ TIME (hr.) DECAY

RADIATION

INTENSITY

\^^ 1

— 1,000 i/hr

7 1/10 100 r/hr

7X7 = 49 (2 days) 1/100 10 i/hr

7X7X7=343 (2 wks) 1/1,000 1 r/hr

FIGURE 2.—Decay in radioactivity is related to time. For every sevenfold increase in time following a nuclear explosion, the intensity of the resulting radiation decreases. When radiation intensity is l,000r/hr 1 hour after an

explosion, at 7 hours after the explosion the intensity would be approximately lOOr/hr, or one-tenth of the

original intensity.

According to this rule, for every sevenfold increase in time following an explosion the resulting

radiation decreases tenfold. For example, suppose the radiation dose rate in an area is 1,000

roentgens per hour (l,000r/hr) at 1 liour after the

explosion. If no more fallout occurs, 7 hours

after the explosion tlie dose rate would be about

lOOr/hr (a tenfold decrease from 1,000). In 49

hours (7x7) or about 2 days, the rate will be down

to lOr/hr. In 343 hours (7X7X7) or about 2

weeks, the rat« will be down to 1 roentgen per

hour. Approximately 14 weeks would be required

for the radiation dose rate to be reduced to O.lr/hr.

Effect of Shelter and Shielding

Shelter

The most important protection against fallout

is shelter. In time of emergency it may not be

feasible to evacuate the population because of the

lack of information about where and when bombs

might explode, and possible sudden and unpredictable shifts in wind direction and velocity which

would determine the pattern of the fallout.

Therefore, farmers sliould be prepared to provide

shelter for their families and livestock, as well as

for their food, feed, and water. For humans the

Office of Civil Defense recommends that a shelter

be designed to provide a protection factor of at

least 100. (It is recognized that shelter for the

large lierds of range animals may not be possible.)

The interval between the explosion and arrival of

fallout may provide the time required to get the

family and livestock under shelter and to cover

water supplies, food, feed, and other critical items.

A guide for adequate shelter reserve food supply is contained in Home and Garden Bulletin

No. 77, "Family Food Stockpile for Survival."

The most critical period of external radiation

hazard is during the first 48 hours after a nuclear

explosion. In an area where the amount of fallout is great enough to have caused a radiation

dose rate of 1,000 to 3,000 roentgens per hour

within 1 hour after the detonation, total loss of

people and livestock without shelter must be assumed. If people and animals can stay within a

good underground shelter for the first 2 or 3 days.
deaths from radiation can be reduced. The more

effective the shelter and the longer it can be mamtained, the greater the reduction in death rate and

other harmful effects of radiation.

Studies on air intakes for shelters indicate that

air ducts with two or more impinging surfaces,

that is, baffles, in the ducts will remove about 95

percent of the particles from the incoming air.

The opening of the intake, however, should be protected from falling dust and faced downward.

Where forced-air shelter ventilation is employed, the design of the air intake and ducts

should conform to that of the Office of Civil Defense regulations.

Radiation Attenuation

Gamma rays are partially absorbed and reduced

in intensity (attenuated) as they pass through any

material. Therefore, shielding of any type gives

some degree of protection. If enough shielding is

provided between the individual and the source of

radiation, such as fresh fallout, the exposure can be

reduced to a negligible level.

Protection from the effects of fallout gamma radiation may be achieved in two ways—barrier

shielding and geometry shielding.

In the first method, a barrier is placed between

the fallout field and the individual. The heavier

the protective barrier, the greater the barrier

shielding effect. Examples of barriers in structures are walls, floors, and ceilings.

Geometry shielding is determined by the extent

of the fallout field affecting an individual, and his

distance from it.

Here is an example of tlie geometry shielding

effect :

If two buildings are of the same height and similar construction, but of different area, the protection from ground contamination would be greater

on the first floor in the building with the larger

area.

On the other hand, if two buildings are of equal

area and similar construction, but differ in height,

protection from roof contamination would be

greater on the first floor of the higher building.

The combined effects of barrier shielding and

geometry shielding result in a shelter "protection

factor." This term is used to express the relative

reduction in the amoimt of radiation that would

be received by a person in a protected location,

compared with the amount he would receive if he

were unprotected. Some speak of a material as

having a protection factor of 10, while others express the same concept with the decimal fraction

0.10. Both mean that the intensity of radiation

behind the shield is about one-tenth the intensity

as measured in the open radiation field.

Appendix B relates shelter categories to corresponding protection factors. It is intended to

provide ( 1 ) a general idea of the relative amounts

RADIATION PROTECTION *

from ground contamination

more protection in building with larger ground

area when buildings are equal in height

FIGURE 3.—Radiation protection from ground contamination.
RADIATION PROTECTIOTT

from roof contamination

more protection in building with greater height

when buildings ore equal in ground area

FiGUEE 4.—Radiation protection from roof contamination.

of protection offered by common types of buildings

and (2) a preliminary estimate of potential shelter

areas, the purpose of survey programs. These protection factors may be conservative in many cases,

since they are based on isolated structures. For

example, if a building is surrounded by taller

buildings, the protection factor might be increased

sufficiently to raise it to a higher protective category. In any case, on-site examination and practical judgment must be used in assigning a protection factor to any given structure.

If special shelters are not available at the time

of a nuclear attack, families should take advantage

of available normal indoor and, preferably, basement-type shelter.

Normal shelter reduces radiation in several

ways:

(1) The source of radiation — the fallout — is

largely outside, on the roof or on the ground and,

therefore, not in Immediate contact with man or

animals, effectively preventing "beta burns";

(2) Radiation is partially absorbed by the roof

and walls of an ordinary house and by the intervening air; and

(3) Eadiation intensity is diminished through

the effect of distance. For example, experience

indicates that a person on the first floor of an ordinary frame house in a fallout area receives about

one-half the gamma radiation dose received outof-doors without any protection. If that person

were in the basement of the frame house, his radiation dose would be reduced to about one-tenth

the value outside the house. An underground

shelter covered with a 3-foot layer of earth reduces

the radiation to less than one-thousandth of the

intensity of that on the outside. Cellars, including

tornado and storm cellars, and stone spring houses

also provide substantial protection.

Decontamination

Decontamination against radioactive materials

is unlike that used against a disease outbreak

where a disinfectant, heat, or some other physical

means is used to destroy the causative organism

of the disease — or in the case of chemical contamination where one chemical is used to neutralize another. Radioactive materials cannot be

destroyed.

Therefore, since radioactive materials cannot be

destroyed, decontamination involves the transport
of the source of radiation (fallout). The fallout

should be removed from a location where it is a

hazard to a place where it can do little or no harm.

Thus, there are two procedures, removal and

disposal.

Work Schedules in Fallout Areas

Even during an early period following fallout,

farm families will be faced with the necessitj' of

doing such farm cliores as caring for livestock and

making other necessary trips into tlie open. If

supplies of food and water have been protected

from contamination and are readily available to

the shelter, appropriate schedules of work and

time in the shelter can be de^^sed that can save

lives and reduce injury to men and animals.

Schedules will depend upon the severity of the

fallout radiation hazard and the urgency of the

task to be ¡performed. In planning emergency

work schedules the guiding principle should be

to keep radiation exposures to the lowest practical limit consistent with saving the community, family, and self.

All but the most important tasks should be postponed as long as feasible to take full advantage

of the decay of the radioactivity. Where possible

the radiation exposure should be more or less

evenly divided among the adults available to perform the necessary tasks. Exposure to radiation

can increase the probability of genetic defects and

may cause other harmful late effects. For these

reasons, tasks involving radiation exposure should.

where feasible, be performed by adults past the

reproductive age.

Civil defense emergency exposure criteria indicate that an acute (short period of time) gamma

radiation exposure dose of 200 roentgens is not

likely to incapacitate more than a small fraction

of the adult population so exposed, and that the

body can gradually repair a large fraction of the

damage resulting from nonlethal radiation doses.

Consequently, a person's total radiation exposure

may exceed substantially 200 roentgens without

seriously incapacitating him, provided the radiation exposure is so distributed over a long period

of time that the unrepaired portion of the injury

does not exceed the injury that would result from

an acute exposure of 200 roentgens. For convenience, the estimated unrepaired portion of a person's radiation dose is referred to as the Equivalent Residual Dose (ERD).

Table 1 presents an example of a work schedule

for areas contaminated with radioactive fallout.

Of course, where feasible, the periods out of

shelter should be much less, particularly during

the first few days when dose rates are high.

TABLE 1.—Example of maximum adult wo7'k schedule for «rer«- contaminated hy radioactive fallout

{4-ioeek basis)

(ERD 100 roentgens; H-l-1 dose rate l,000r/hr—equivalent to about lOOr/hr at H-|-7, or 22r/hr at H-|-24 hours;' shelter

factor of 100—1% of unsheltered dose)

Time after explosion

Work period

(time out of

shelter) ^

Time after explosion

Work period

(time out of

shelter per day)

12 hours (same day or during first 24

hours).

2d 24 hours - - _ -. _ _

Hour

1

1

4th through 7th day

Hours

2

8th through 14th day 3

15th through 21st day

22d through 28th day

4

3d 24 hours . _.. 6

' Equivalent dose rates for H-|-7 and H-l-24 hours are stated in order that those possessing "citizens instruments"

be able to measure the degree of fallout contamination in their specific areas and adjust the work periods to suit their

situations. See text.

2 Work periods may be split—part morning and part evening, for instance. It is assumed that most of the work period

on the first day would be spent in a barn or similar structure and that on succeeding days at least one-fifth of the work

period would be spent in such structures which provide some protection. First 2 weeks—off-duty hours spent in shelter

allowing no more than 1 percent of unsheltered radiation to penetrate. Third and fourth weeks—major portion of the

worker's off-duty hours spent in shelter but limited fraction of time could be spent in a typical basement or cellar.

For other degrees of contamination the example

may be "scaled" to a degree. If the fallout contamination were double that assumed for table 1,

humans might work for half the length of the

indicated work periods, provided they had shelters with twice the protection. Unless it has been

determined that there is no radioactive fallout in

the area, all members of the farm family should

remain within their shelter during the first 24

hours. Also, if fallout is heavy, say above 1,000

roentgens per hour at 1 hour after detonation,

there would be little value in attempting to care for

livestock unless they were protected by a shelter

at least as good as that provided by a basement.
In the far more extensive areas where contamination is less, scaling of the example presents

greater promise. With half the fallout radiation

intensity (500 roentoens per hour at H + 1 or its

equivalent, 50 roentgens per hour at H+ 7, or 11

roentgens per hour at H+24) livestock could remain healthy with less shelter protection, although

some shelter is still required. Given the same

human shelter protection assumed for the area

when the radiation intensity was 1,000 roentgens

per hour at 1 hour^ltei blast, the uiaAmium work

scheduled could be doubled, if necessary.

However, the work schedule presented in table 1

is a maximum for radiation exposures approximating those that would incapacitate. The

schedule also allows considerable time for performing most of the important duties. Under

less severe fallout conditions, one would be wise

to stay within the time limits shown, if possible,

and correspondingly reduce his personal radiation

exposure with its associated hazards.

Handling Livestock

Livestock owners will generally find it impractical to remove animals from fallout areas.

Therefore, facilities for the care of the animals in

shelter and adequate supplies of uncontaminated

feed and water for at least 2 weeks would be

needed.

If warning of fallout is received, preparations

should be made for the best possible care of

animals.

(1) In the expectation of the immediate possibility of radioactive fallout, the following should

be observed :

(a) If sufficient time is available, animals

should be brought into shelter. Animals

should be kept within shelter at least during

the first critical period of 24 to 48 hours. A

good tight barn would reduce radiation dose

by about one-half. The best shelter given

Livestock Protection

Fallout

Shielding

Clean Water

Safest Area

FlQUEE 5

10

-The best protec-tion likely to be available for Uvestock against radioactive fallout is in the basement of

tight bam with a loft filled with hay.
by a structure normally in use for livestock

IS a 2-story basement-type bam with a storage loft filled with hay. Proper use of shelter for animals can substantially reduce the

number of deaths and injuries from radiation.

(b) Milking cows must be given the most

protected place in the barn, not only for the

sake of the animals but also for the safety

of the milkers. The animals' feed should be

reduced to the minimum needed for subsistence.

(c) Provision should be made for a reserve stock of food in the house and feed in

the barn for the farmer and his family and

for the animals for at least 2 weeks.

(d) If only a limited resem^e of feed is

stored so that it will not be contaminated,

this feed must be reserved for one or only a

few milking cows. This milk can then be

used by the farmer and his household, primarily for children.

(e) If time allows, already harvested feed

lying in the open should be covered with available materials such as tarpaulins. As much

as possible of ready-to-harvest crops should

be harvested and protected.

(f) Animals that are not placed in a barn

or under a roof might, if possible, be placed

under trees or where they are covered to some

extent.

(g) It is better to keep animals alive on

contaminated feed and water than to let them

die from starvation.

(h) Take care to protect as big a water

reserve as possible. In case of radioactive

fallout, it should be remembered that water

from sufficiently covered wells not containing

surface water must be considered drinkable.

During the critical emergency period, in

areas contaminated with fallout, the use of

water from lakes, creeks, other surface

sources, and collected rainwater should be

restricted. Use the protected water first.

(2) It may happen that warning will not

reach the farmer in time and, therefore, he will not

be able to handle his animals in the proper manner as explained in (1). These animals may be

directly exposed to fallout. If practical, they

should be thoroughly washed off as soon as it is

possible for the farmer to stay outside for a

limited time. After being washed, the animals

should be taken into the barn, or other available

shelter. During the washing, the farmer should

wear protective clothes, including rubber shoes

and gloves. The removal of radioactive fallout

from the hide of the animal is difficult and may be

ineffective in some cases. However, it will help

to reduce the radiation exposure of both the animal

and the animal caretaker or milker.

Acute total body radiation exposures of livestock (cattle, sheep, and swine) varying from 500

to 600 roentgens provide a midlethal dose—or

the dose level that you could expect to kill 50

percent of the animals within 30 days. Poultry

are more resistant, liaving a midlethal dose of

about 900 roentgens. However, tolerance varies

among species of animals as well as among animals

within the same species.

TABLE 2.—Percentage of mortality of unsheltered

animals after 2Ji.-hours'' exposure to various

radiation doses

Species

Cattle..

Sheep--

Swine. _

Poultry

Mortality

100% 80% 50% 20%

Exposure dose (roentgens) '

650 600 550 450

700 600 525 450

800 700 600 450

1,200 1, 100 900 600

300

350

350

400

' Exposure dose in area where livectock and building

are located.

All domestic animals have a similar response to

total body irradiation. Few if any die after exposure to 250 roentgens. And few if any survive

an acute dose as high as 1,000 roentgens. Smaller

doses or slower dose rates are tolerated better than

faster delivered large doses. Some animals like

swine have a much faster recovery rate than

others like the burro, although there is little

difference in response of the species to acute exposure. The body size of the animal has little to

do with survival, although the very young or the

very old may be more radiosensitive.

Poultry

As indicated in table 2, poultry are among the

more radioresistant species of our domesticated

animals. Therefore, poultry may represent one

of the more dependable sources of fresh foods

of animal origin which may be available after a

nuclear attack. Furtliermore, most of the poultry

raised are reared under shelter or are provided

with some shelter available for protection from

the normal environment. Consequently, compared with other livestock species, poultry should

enjoy the greater chance for sunnval following a

nuclear attack, because of the greater availability

of immediate shelter for protection from radioactive fallout.

Still another factor to support the above conclusion is that most poultry are raised on commercially prepared or packaged grains or feeds

and, moreover, these feeds are necessarily stored

under some form of shelter. Therefore, considering the various livestock diets, poultry diets are

least likely to be contaminated by radioactive

nuclides. Thus, the hazards of direct and indirect

11
(via the diet) fallout contamination are significantly reduced.

Shelter

The value of shelter in preventing death and

sickness among animals is greatest in areas exposed to acute radiation doses about equal to the

average midlethal dose (550 roentgens). At low

radiation intensities, there is little beneficial effect

from shelter because no animals would become

sick or die whether sheltered or not. At high

intensities of outdoor radiation, all animals would

die under either condition.

Table 3 indicates the percentage of mortality

that might be expected among various species of

sheltered and unsheltered animals exposed to different intensities of radiation. This information

should be considered as a general guide of expected mortality based on current knowledge, and

not as a forecast of exact mortality rates.

The objectives of providing shelter for livestock

and pouhry are to (1) protect livestock from the

lethal effects of radiation, thereby conserving an

important food resource and (2) protect the feed

and water of food-producing animals from radioactive contamination, thereby assisting the production of safe food products for human consumption. After the first critical 24 to 48 hours or when

outdoor work periods can be scheduled, livestock

can be given short periods of exercise in areas or

yards that do not contain contaminated vegetation

or water. ^Yi\en it is no longer practical to keep

animals off contaminated pastures, supplemental

feeding with unconttttiiinamd-fg5crsHoïïran>e pr

vided as far as possible. (See Appendixes ü anu

C for protection factors and suggested livestocK

shelters.) . .

Food animals that have received radiation doses

that may result in sickness or death may not show

any injury within a period of 2 to 10 days after

exposure.

Meat from animals exposed to lethal doses of

external radiation may be used for human consumption without great hazard from radiation.

The greatest danger to human health in this case

would come from bacterial invasion of the tissues

as a result of radiation sickness. This may occur

between the 7th and 12th day after exposure.

Briefly, animals can be safely used for food if

they show no temperature rise or apparent injury

or illness. Temperatures may rise from 101.5° to

108-110° F. when bacterial invasion occurs. Some

normally edible organs, such as the liver, would

not be safe.

If any animal shows signs of sickness, it should

not be slaughtered for food purposes until it is

fully recovered and in good health. This may

take several weeks or months. Sick animals may

be treated according to the symptoms shown.

However, if animals have ingested or inhaled

fallout, the butchering process would be complicated by the additional exposure of the workers to

fallout on the animal's hides and in the alimentary

and respiratory organs. These organs (lungs,

trachea, stomach, intestines, esophagus, tongue,

and lips) must be removed so as to avoid contamTABLE 3.—Effect of shelter on the mortcdity rate of livestock ^

Kind of livestock and radiation exposure—

unsheltered dose (number of roentgens—1 day)

Cattle

500_-

1, 000.

3, 000.

Hogs

500-_

1, 000

3,000

Sheep

500..

1, 000

3,000

Poultry

500-_

1,000

3,000

Mortality rate by nature of shelter

No shelter

Percent

30

100

100

30

100

100

38

100

100

10

64

100

Tight wooden

barn (protection

factor of 2)

Percent

0

30

100

0

30

100

0

38

100

0

10

100

2-story barn with

loft full of hay

(protection factor

of 5)

Percent

0

0

80

0

0

50

0

0

80

0

0

20

Basement-type

barn with loft

full of hay

(protection factor

of 10 or more)

Percent

0

0

0

0

0

0

0

0

0

0

0

0

' The reduction of radiation by shelter is described as the "protection factor." For example, if the protection factor

of any given structure is 2, then the intensity of outside radiation is reduced by one-half. See appendix B for additional

information on protection factors for other types of farm dwellings. In fallout areas, one-half or more of the radiation

would be released after the end of the first day.

12
inating usable parts. In this case, only muscle hides, organs, and other parts containing fallout

and muscle fat would be safe for use as food. The must be disposed of by burial.

Irradiation Effects on Animals

General

In general, domestic animals are about as radiosensitive as man. There is no specific therapy for

radiation sickness. In presumed cases of serious

radiation in]\uy, animals should be placed under

observation and treated symptomatically if signs

of radiation sickness appear. Animals surviving

the first few weeks following a brief exposure may

be expected to recover.

Limited studies indicate that unsheltered animals that fail to develop beta burns after having

been in the path of a fallout cloud will ordinarily

escape serious external radiation injury. Animals

that sustain exposure intense enough to produce

beta burns but live longer than 3 weeks or a month

should recover.

If areas have been subjected to sublethal

amounts of fallout, animals may develop signs of

radiation sickness. Such animals might be placed

on clean, uncontaminated feed and treated symptomatically. Treatment may include the use of

antibiotics until they either recover or die from exposure to radiation.

Sexual and Genetic Effects

Sperm or ova production is halted following

total body irradiation in the lethal dose range of

300 to 800 roentgens, and is not resumed until

several weeks after general recovery. Male animals irradiated within the lethal range, however,

maintain some interest in females in estrus up to

just a few days before death. These animals may

be fertile, as spenn may survive in the testes for

a number of days after exposure to radiation.

Doses in the lethal range are necessary to produce

sterility.

Embryologie Effects

Irradiation of the embryo is particularly hazardous. Doses ordinarily without danger to the

female can be of grave consequences to the embryo

during early pregnancy. The abnormalities encountered are associated almost entirely with

cessation of development of growth of a particular organ or organ system brought about by

irradiation.

PROTECTION AGAINST INTERNAL RADIATION

FROM FALLOUT

The second phase of radiation hazard from fallout is internal radiation ; that is, exposure to the

radiation from isotopes that enter the bodies of

animals and human beings. These radioactive

elements generally enter in food and water.

At first, the principal source of internal radiation is external contamination of edible plants

when fresh fallout drops on the affected area.

For livestock, this would include primarily forage

grasses and legumes. For man, it would include

fruits, vegetables, and milk — the last particularly for children. As time passes and the initially contaminated food and feed have been

discarded, the principal source of internal radiation for man and animals is indirect — from the

radioisotopes in the soil which are absorbed

through plant roots into food and feed crops.

"V-N^ien meat and dairy animals eat contaminated

feed, some radioactive elements are absorbed into

their bodies. Thus, man's food supply of both

plant and animal products can become contaminated with radioactivity.

Radioisotopes Causing Internal Radiation

Many of the radioactive isotopes created by nuclear explosions are of minor concern, in the hazard of internal radiation, because of (1) the small

amounts involved; (2) their extremely short or

extremely long half-lives; or (3) the fact that

they are not incorporated into the food chain (see

glossary) and hence do not seriously affect man

and animals.

Among the isotopes that are taken up m the

food chain are the following : Barium 140, cerium

144, cesium 137, iodine 131, iodine 133, promethium 147, ruthenium 106, strontium 89, and strontium 90. Of these, the radioactive isotopes of

most significance as internal radiation hazards are

barium 140, iodine 131, iodine 133, cesium 137,

strontium 89, and strontium 90.

Radioactive iodine, because of its chemical

identity to ordinary iodine, accumulates in the thyroid gland when it gets into man or animals.

However, iodine 131 has a relatively short halflife of 8 days. Iodine 131 will not be an important long-term fallout hazard, but it is the most

hazardous internal emitter during the first 60

days. When considering the dosage to the thyroid derived from radioiodine in the first few

days after attack, it is important to consider both

644700 0—62- 13
MOVEMENT OF STRONTIUM 90

On and Into Plants

r 90 absorbed

by leaves

and soil

•••••••

FIGURE 6.—When fallout first arrives, It falls on the surface of the plant and soil. As time passes strontium 90 is

absorbed into the plant leaves and into soil where it is available to be taken up by the plant roots along with

nutrients.

iodine 133 and iodine 131. Iodine 133 has a halflife of 22 hours but occui's in sufficient quantity

to make a significant contribution to the thyroid

radiation dosage.

Cesium 137 has a long half-life of 27 years and

is chemically similar to the essential nutrient element potassium. When cesium 137 is consumed

and absorbed, it is found primarily in muscle

tissue and can cause several types of cell damage,

including genetic damage. But this radioisotope

is not retained long in the body. It continually

enters and leaves the system

potassium.

Strontium 90, however, with a

years, is of primary importance,

is chemically identical, but it has a half-life of

only 53 days. They behave much like calcium in

soils, plants, and animals. Nuclear explosions

produce large amounts of radioactive strontium.

It is taken up in biological systems, in plants, is

secreted in milk, and collects in bones, where some

of the strontium !)0 remains for years. Radioactive isotopes of strontium deposited in the bone

14

just as does

half-life of 28

Strontium 89

probably can produce serious consequences, such

as bone cancer. Children are relatively sensitive

to radiostrontium, because during their early

growth period they require larger quantities of

calcium than adults, a greater fraction of the ingested strontium is deposited in their bones, the

concentration of strontium is more uniform

throughout their skeletons, and because they have

longer life expectancies for a slowly developing

disease such as bone cancer to occur.

Barium 14-0 behaves similarly to strontium 89

and strontiimi 90 in that it is deposited in the bone.

However, both the proportion of ingested barium

140 that reaches the skeleton and the half-life

(12.8 days) are smaller than for radiostrontium,

so that barium 140 contributes less to the bone

hazard.

Although the radionuclides mentioned above

are of special concern in view of their predominance in the food chain, total fission products in

fallout have to be considered in the event of food

being contaminated directly with fallout. While
only the group described above passes into the

blood stream in significant quantities, the entire

material irradiates the gastrointestinal tract as

it passes through and can cause serious injury.

The results of tliis damage are among those that

appear earliest.

Protection of Food, Feed, and Water

The concern in protecting food, feed, and water

is to prevent the consumption of contaminated

materials that would subject man and animals to

internal radiation hazards. However, the immediate problem is to protect a sufficient quantity

from fresli fallout to provide for survival during

the critical period.

The principle of protecting food, feed, and

water from external fallout is simple: Prevent

the fallout from becoming mixed or incorporated

into these materials. They may be irradiated by

the fallout, but if the radioactive particles do not

come in actual contact with them — or if the

fallout is removed — tliey will not be radioactive

and tlius will be safe to eat or drink. Methods

of prevention would be the same as those for preventing dust from contaminating food or water

if tlie air were lieavily dust-laden. Fallout can

also be removed in much the same way as dust —

by washing, vacuum cleaning, and brushing. Precautions should be taken to avoid inlialing or ingesting the material while removing it.

Food

Radioactive fallout deposited on agricultural

land will contaminate food chains with radioisotopes by way of the soil and crops. It may, depending upon the radiation intensity level, prevent farmworkers from handling crops properly.

The deliberate overexposure of farmworkers to

radiation in order to save contaminated crops that

are not essential or might be discarded later is

not warranted. Depending upon the stage of

growtli when fallout occurs, salvage of unharvested crops such as grain, fruits, and vegetables

would be impaired By crop contamination, external exposure hazard, and unavailability of fuel

and machinery.

For example, if fallout is heavy, ripe fruits

may be lost because of the personal hazard in

harvesting them. Fruits that do not have to be

picked immediately and that can be decontaminated by washing and peeling before eating can

probably be saved. Orchard trees should be maintained as usual and the fruits monitored for

radioactivity.

Consequently, the land contamination problem

in heavy fallout zones would be primarily a longterm soil contamination problem. For most crops

and soils, about 1 percent of the available strontium 90 in the soil is removed in a single crop.

On sandy soils, some crops may remove as much

as 5 percent. Even at this higher rate of removal, more than 40 crops would be required to

achieve 90-percent decontamination of the soil.

Fallout particles that fall directly on food and

forage plants contaminate them by remaining attaclied to the aboveground parts, or by releasing

radioisotopes that are absorbed into the leaves and

other plant parts. Rain and wind move tliese

particles from plants to soil, but certain characteristics of the leaves, such as hairiness and roughness, increase the retention while smoothness reduces it.

Strontium 89, strontium 90, and ruthenium 106

absorbed into leaves tend to remain there because

they do not move readily into the other parts of

the plant from the leaves. On the other hand,

cesium 137 and iodine 131 will move readily

throughout the plant from the leaf. Accordingly,

internal contamination by strontium 89, strontium

90, and ruthenium 106 from leaf absorption is

greatest in leaves and is comparatively less in

fruits, seeds, and edible roots and tubers. As the

season progresses, the fallout contaminants that

have accumulated in the leaves, especially strontium 89, strontium 90, and ruthenium 106, may be

washed from the leaves to the soil in rain and

dew. They may then be absorbed by the roots and

distributed throughout the entire plant and

thereby increase the total content of contaminants.

In arid regions with little rainfall these contaminants are not washed to the soil from the leaves,

and any new growth that develops after the fallout will be relatively lower in strontium 89, strontium 90, and ruthenium 106.

Vegetables and fruits harvested from fallout

zones in the first month after attack will require

decontamination before they can be used for food.

First, the exposed parts must be thoroughly

washed to remove the fallout particles. Then

vegetables or fruits should be peeled, pared, or

the outside otherwise removed in such a way that

hands or utensils do not contaminate the parts to

be eaten. It should be possible to decontaminate

almost completely such crops as apples, head lettuce, and cabbage by repeated parings, washing

hands, and washing utensils before each paring.

Since fresh fallout provides only surface contamination, it should be possible to wash and shell peas

and beans or husk sweet corn to remove the contaminated parts. This type of decontamination

could be applied to many human food items in the

home immediately after harvest, preferably using

well water, or other noncontaminated water.

Cooking will not destroy radioactivity.

Some food products that have fallout on or

mixed in them can be used only after holding l;he

products long enough to allow the radioactivity

to decay to a safe level. Storage of the contaminated material for a period ranging from 2 weeks

15
to several months, depending upon the degree of

contamination, will reduce the amount of radioactivity present, usually to a negligible level. This

is due to the comparatively fast rate of radioactive decay. Obviously, many food products, including most meat that is not canned, could not

be stored for the necessary time. Fallout on unpaekaged meat presents a salvage pi-oblem, since it

is extremely difficult to remove the outer surface

without carrying contamination onto other parts

of the meat. Washing is not an effective method

of removing this type of contamination. Meat

products contaminated with fresh fallout could

be canned and then stored until the radioactivity

had decayed sufficiently.

Meat and meat food products in home or commercial storage will be most effectively protected

if canned. For uncanned products, a sealed covering of one of the commonly available plastic films,

such as polyethylene, will provide adequate protection from contamination by fallout. Even

fiberboard and similar tight containers that will

exclude dust will Ije-ÊAectiro^—Reírigeraííon facilities should be maintained as usual to control

spoilage.

Feed and Water

Because early radioactive fallout is dustlike in

character and results in surface contamination,

the simplest method to protect feed and water is

to place a cover over them to prevent fallout from

coming in direct contact with the materials.

Grain stored in a permanent bin and ensilage in

a covered silo are provided with adequate protection against fallout, and the contents can be safely

used as soon as the farmer is able to get into the

area to use them. The haystack in an open field

can be protected with a covering such as a tarpaulin. The fallout will lodge on the tarpaulin,

but by carefully removing it, the radioactive fallout will be removed. The hay and the contents of

the feed bin and silo would not be radioactive and

could be used immediately as safe feed for liveProtection - Feed and Water

Well or Spring

^''TitlTht ^¡Felfl\^ Z\uT^:L7'' ^'^"' 'T^'^'K'''' ''''' "^^^ "''^t^'- P-^^^^^t fallo'^t f'-o«^ becoming mixed

far:¿ rTmra'fr^m^Lt^ov^erAVeTeïa^ ^-^ «>- ^-<^^-ed, w.en t.e

16
stock. Many materials such as uncovered haystacks and piles of farm produce may be safely

used as food and feed if the contaminated outer

portions are removed.

Water stored outside—such as in stock water

troughs—should be covered with any material that

would normally keep out dust. Larger farm ponds

and lakes would be difficult if not impossible to

protect. As time passes the problem of contamination of ponds and lakes may not be a major

problem. The dilution of the radioactive fallout

in the water and its adsorption by clay on the

sides and bottoms of the pond or lake will be effective in reducing the liazard below that of the

surrounding land. The mere boiling of water contaminated with radioactive particles will not make

it safe but distillation does remove nearly all of

the radioactive material.

Water from covered sources, such as springs and

wells, would be essentially free from contamination even in heavy fallout areas and could be used

for man and animals with confidence.

Radioactive Iodine and Radioactive Strontium in Food

The study of radioactivity in milk has been more

Avidespread than in other foods for several reasons.

Milk provides a vital part of the Nation's diet,

particularly for young children, invalids, and

older people for whom substitutions in diet are

difficult. Because of the normal system of production and distribution of milk in this country,

it is one of the easiest foods to obtain for testing at

central points and, therefore, more testing of milk

has been done. Milk is produced throughout the

year in all sections of the country so that samples

are always available.

Several radioisotopes ingested by dairy animals

can be secreted in milk to an appreciable degree.

Among them are iodine 131, strontium 89, strontium 90, barium 140, and cesium 137. The most

important of them are usually considered to be iodme 131, strontium 89, and strontium 90. The effects of others are believed to be less important.

Radioactive Iodine

For a period of days following a heavy deposition of fresh fallout, iodine 131 may be a major

radioactive contaminant of vegetation, including

food crops such as fresh vegetables and fruits.

After ingestion by animals, iodine is rapidly absorbed from the gastrointestinal tract, collected

in the thyroid gland, and secreted in milk and

eggs.

In the event of a nuclear attack, radioiodme

would be the most critical single factor in the contamination of milk during the first few weeks

after an explosion. The hazard would decrease

relatively rapidly (see table 4) because of radioactive decay, but the short-time problem would be

serious in some areas.

A large fraction of the radioiodine ingested by

human beings, ranging from about 20 percent for

adults to 50 percent for children, is deposited in

the thyroid gland. In addition, children are relatively more sensitive to radiation of the thyroid

than are adults. It has been estimated that the

ingestion of 5 microcuries (see glossary) of radioiodine would result in a dose of 200 rads (see glossary) to the infant's thyroid. The infant thyroid

weighs about 1.5 grams, whereas the adult thyroid

weighs about 20 grams. For several reasons, thereTABLE 4.—A general guide to the periods of time

before contaminated milk should be consumed '

Roentgens per hour

Time before consumption by—

atH-t-l

Infants

under 2

years

Children

2-16

years

Adults

over 16

years

10

30

100

300

Weeks

0

1

3

5

Weeks

0

0

1

3

Weeks

0

0

0

0

1 Estimates based on radioiodine contamination and the

rate of its radioactive decay. To be used only if adequate

alternative sources of milli are available and if specific

local information is lacking.

fore, a greater amount of radioiodine is required

to damage the adult's than the infant's or child's

thyroid.

Table 4 is a suggested guide that would result

in a milk contributing not over 200 rads to the

child's thyroid or 1,000 rads to that of the adult.

Table 4 is intended as an approximate temporary

guide to the usability of fresh milk during the

fii'st part of the critical postattack emergency

period. If alternative uncontaminated sources of

milk in various forms are unavailable or inadequate for subsistence, the guide should be ignored

to the extent necessary for the maintenance of life

and general health. As alternative assessment of

the food situation and analytical measurements

on milk become available with the passage of time,

the general guide should be supplanted by specific

knowledge of a local situation.

Since milk is an essential food for infants and

other young children, and the weight of milk consumed by them is high in relation to their body

weights, the contamination of milk witli radioiodine during the first weeks after nuclear attack

would be primarily a problem of thyroid injury

to young children.

Studies indicate that sheep whose thyroids have

been exposed to radiation doses ranging from

50,000 to 70,000 rads do exhibit serious patho17
logical and physiological disfunctioning. Observations on cattle show that they require at

least twice the radiation dose of sheep for thyroid

changes.

The hazard discussed here is created by dairy

animals orazing on vegetation contaminated witli

radioiodine from fallout and thus producing contaminated milk. Available information indicates

that from 5 to 10 percent of tlie daily intake of

iodine 131 is secreted in milk of dairy cows. On

the basis of current knowledge, suggestions have

been developed for reducing the hazards of radioiodine in milk in the event of a nuclear attack.

Milk produced from pastures that received

fallout equivalent to a radiation level of 30

roentgens per hour or higher 1 hour after a

nuclear bomb explosion should not be used immediately for consumption by infants. For example, several days after a nuclear explosion, civil

defense authorities measure the radiation level in

a given area. F'rom this measurement, the equivalent radiation level at H + 1 can be calculated. If

this is as high as 30 roentgens per hour, then milk

produced by cows grazing in that area should not

be used as fluid milk by infants for 2 weeks after

the explosion, unless speciñc radioiodine measurements show the milk to be safe or other sources

of usable milk are lacking. Table 4 indicates the

time before acceptance at other levels of radiation.

It would be best to have a means of expeditiously determining the iodine content of milk; for

example, a special monitoring instrument (milk

counter probe for radioiodine). Until such equipment is developed and available, table i can be

used as a guide.

Stockpiles of storable milk or milk products

for children are needed. Some areas, aiïected by

fallout but not by the bomb blast, may not be

producing safe fresh milk for 2 months if the

above standards are met. Therefore, families with

children should keep an ample supply of powdered

milk, whole or skim, or canned milk on hand to

help provide necessary nutrients during this period. This supply should be rotated into current

use and the reserve replenished regularly.

Reducing Iodine 131 Contamination of

Food and Dairy Products

On the premise that radioactivity from iodine

131 has largely disappeared from materialt^ after

a 2 months' period, the dairy farmer can confine

lactating animals to the barn before the appearance of fallout in the area and provide forage and

feed that had been harvested before the detonation

or stored for 2 months after exposure to fallout.

Freshly contaminated forage can be fed to nonlactating stock. Concentrated mixtures prepared

on the fann should be prepared from grains harvested before the fallout or that have been stored

for 2 months or longer. Ensilage that has been

stored for at least 2 months could also be a safe

feed for dairy animals.

18

Confining dairy^fcnimals to reasonable dusttight buildings and providing them with clean,

noncontaniinated feed and water will aid greatly

in minimizing the contamination of the dairy

products produced.

If, despite all precautions, fluid milk supplies

should become contaminated, a number of steps

could be taken to avoid danger to consumers.

Since the half-life of iodine 131 is only 8 days, its

decay is moderately rapid and delayed mai-keting

is a key to safe usage of contaminated milk and

dairy products.

If the contamination of milk supplies with

iodine 131 were fairly localized, milk from other

areas with little or no contamination could be diverted to contaminated areas for immediate consumption, and the contaminated milk processed

and stored for later consumption. If contamination were widespread, this might be impractical

and consumption of fresh fluid milk would have

to be deferred until radioactivity was reduced to

safe levels.

For high rates of contamination, storage for 1 to

2 months might be necessary before iodine 131

was reduced to safe levels. Freezing of packaged

milk in paper cartons for storage before delivery

would be one way of handling the problem. The

frozen product would be thawed before delivery to

the consumer and the consumer would have no

responsibility for keeping track of storage time.

During the period when fresh milk supplies were

not available, reconstituted dry milk or canned

milk could be safely used.

Any of these marketing modifications would be

difficult. Nevertheless, they could become necessary.

There should be no destruction or disposal of

milk contaminated with iodine 131, since it can

be processed into products such as butter, cheese,

powdered milk, and canned milk, and stored for

a period of time to allow the decay to take place.

If processing facilities are not available locally

or are not adequate to handle all the milk involved,

the contaminated milk can be fed to pigs or calves.

Infants and persons with special dietary

needs should get safe milk supplies where limited. During the first weeks after the explosion,

adults and children who can get an adequate diet

from other foods should leave the restricted safe

milk supply for infants and others for whom it is

a mainstay in the diet. Mothers should breastfeed their babies during this period insofar as is

consistent with medical advice.

Milk produced from existing vegetation in

areas of higher radiation levels can be converted into storable dairy products or animal

feed. In areas for which the relevant radiation

level at H + 1 was from 30 to 300 roentgens per

hour, dairy cattle may have to continue to graze

contaminated pastures. The milk production can

be converted into such products as dried milk,

canned milk, cheese, butter, and ice cream. These
products should be stored until the radioiodine has

decayed to a safe level as indicated by table 4.

The milk might also be fed to calves or pigs, and

the meat thus produced would be safe for human

consumption.

Radioactive Strontium

After the first 60 days, the principal hazard of

radioactive contamination in milk arises from

strontium 89 and strontium 90. The strontium 89,

however, will have virtually disappeared by 1 year

after its fonnation. Just as other radioactive

isotopes of fallout, strontium 90 falls on the surface of plants and can be consumed with foods

and forage. Some of it is deposited directly on

the soil or washed into it, remaining indefinitely — for all practical purposes — in the top several inches.

The return to earth of strontium 90 in worldwide fallout from large nuclear detonations is

rather slow. Raijifall is the principal mechanism

that brings stratospheric strontium 90 to the

ground from the air.

Strontiimi 90 movement into plants has an important association with plant physiology and soil

conditions. There are two general routes of

entrance for strontium 90 into plants. The first

is direct contact with the parts of the plant occurring above the soil. As time passes, following

the deposition of fallout, the second route •— entrance into the plant roots through the soil — becomes relatively more significant.

Strontium 90 enters plants by three means

other than from the soil through the root system.

These avenues are floral, foliar, and stem base or

root mat.

The floral route is fairly common in plants.

Cereal grains are good examples. Rain bearing

strontium 90 collects in the upturned flower of

the plant. At least a part of this contamination

is retained by the developing kernels.

Strontium 90 may also gain entrance into the

plant by foliar absorption, that is, through the

leaves. There is, however, little movement of

strontium 90 from the leaf to other parts of the

plant. Consequently, the oldest leaves of a continuously exposed plant have the heaviest internal

concentration. With cabbage or head lettuce, removal of the older outer leaves removes most of

the contamination from this source. Grazing

animals, however, usually consume these parts of

grass if the pasture is used at its optimal capacity.

Another route for the entrance of strontium 90

into a plant occurs in permanent pastures composed of perennial grasses having a root mat, by

absorption into living roots and stem bases in the

mat.

As a rough approximation for sloping land,

about 90 percent of the strontium 90 that falls on

the soil will remain where it falls. Studies indicate that soil material eroded by surface runoff

is about 10 times as high in strontium 90 as the

remaining soil. Small areas at the base of slopes

may accumulât« this material. Areas subject to

accumulation should be monitored frequently,

especially if used for food crops.

Radioactive Strontium in Food

Strontium is similar to calcium in behavior and

is closely associated with it in soil and food and

bones. Strontium in the soil is taken up by plants

along with calcium.

Fortunately, the metabolic processes of both

animals and humans act to reduce substantially

the amount of strontium that is deposited in the

bones of man relative to that of calcium, as compared to the amount that was originally present

in the vegetation and in the soil on which it grew.

This protective mechanism is measured by the term

"discrimination factor" and refers to the natural

preference that the body has for calcium over

strontium. Relatively more calcium than strontium is carried along as these elements move together through the food chain from the soil to the

plant and then through the body to the bone. In

milk the discrimination process operates twice.

The biological system of the cow screens out over

90 percent of the strontium in her diet, and the

biological system of man screens out still more

of the strontium consumed in milk. The same is

true, but to a lesser extent, in the production of

meat and eggs.

About 70 to 80 percent of the calcium in the

average diet in this country comes from milk and

cheese. But calcium from these sources carries

only about -iO percent of the soil-derived strontium

associated with our food.

Meat and eggs contribute only about .5 percent

of the calcium and 5 percent of the soil-derived

strontium in the diet. Plant foods — grains,

vegetables, and fruits — furnish about 15 percent

of the calcium in the diet but, because they are

consumed directly, they would furnish about 55

percent of the total soil-derived strontium.

Because of the discrimination factor within the

human body, the ratio of strontium to calcium retained in the bone is only about one-fourth to

one-half (the latter value is especially applicable

to children) as great as the ratio of these two elements in the diet. For example, if the ratio in

the human diet is 16 micromicrocuries of strontium 90 to 1 gi-am of calcium, then the ratio in

the bone will be about 4 micromicrocuries of strontium 90 per gram of calcium.

Milk should continue to be the outstanding

source of calcium in the diet, because the calcium

it supplies has had much of the strontium present

in the vegetation screened out by the biological

system of the cow.

It should be remembered that milk is an essential source of calcium for the bones and teeth of

growing infants and children. Any widespread

disruption of the production and distribution of

this nutritionally essential commodity could create

19
SOURCES OF CALCIUM AND STRONTttJMTO

From Food

CALCIUM STRONTIUM 90

^ MILK

^ PLANTS

myj MEAT

FIGURE 8.—Sources of the calcium and strontium 90 that are contained in human bones are principally milk, plants,

and meat. The discrimination factor is demonstrated by the large percentage of calcium derived from milk

while the relatively small amount of strontium 90 is being accumulated.

individual and public health hazards far more immediate and serious than might be created by the

amounts of radioactive exposure involved at low

levels of strontium 90 contamination.

Additionally, reduction of milk consumption

by children, without competent medical supervision, could not only result in nutritional imbalance

but might actually increase strontium 90 exposure,

since milk has a lower strontium-to-calcium ratio

than other foods.

Also, results of research on animals indicate that

a body well nourished with respect to calcium does

not retain so much strontium as a body that is

deficient in calcium.

In a contaminated environment, rations for

dairy cattle can influence the strontium 90 content

of milk. For example, a diet of grass hay, corn,

and inorganic calcium would provide less strontium for the animal than a diet of legumes, such

as clover, lespedeza, or alfalfa, which are good

sources of calcium but which Avould also contribute

a greater amount of strontium.

Eesearch studies clearly show that the level of

strontium 90 contamination of milk will depend

upon the amounts of strontium 90 and calcium in

the ration. There would seem to be little gain in

20

simply adding mineral calcium to an otherwise

adequate diet. First, any dietary modification

would have to be carried out continuously over a

reasonably long time period to permit adaptation

of the animal. Secondly, it would be difficult to

get a dairy cow to eat more than 200 to 300 grams

of calcium per day and higher levels might be inadvisable from the standpoint of the health of

the animal. Thus, if animals were normally consuming about 80 grams of calcium per day, a reduction factor of 2 to 3 is the most that could be

expected by increasing the calcium intake on a

usual diet.

A ration consisting of 8 pounds of alfalfa hay,

12 pounds of timothy hay, and 12 pounds of grain

would supply a dairy cow with about 80 grams

of calcium ; mineral supplementation to 160 grams

daily would be expected to give a reduction factor

of about 2. On the other hand, a ration of 20

pounds of timothy hay and 12 pounds of grain

would supply about 40 grams of calcium per day,

and supplementation to 160 grams would provide

a reduction factor of about 4. The two reduction

factors are comparable only if the total strontium

90 is equal in both rations.

In the event that it is necessary to shift from
legume hays to the feeding of grass hays to dairy

cattle and to supplement their calcium intake, it

is recommended that the gi'ass hays be liberally

fertilized \YÍth nitrogen fertilizer in order to get

acceptable yields and that the hays be harvested at

the stage when they will be most palatable and

digestible and contain the greatest yield of usable

nutrients per acre.

To help assui'e the availability of a safe milk

supply following a nuclear disaster, cooperative

research between the U.S. Department of Agriculture (Agricultural Research Service), the U.S.

Department of Health, Education, and "Welfare

(Public Health Service), and the U.S. Atomic

Energy Commission is resulting in the development of a procedure for removing radiostrontium

from milk. The procedure is similar to that used

in many homes to take the hardness out of water

and to that used in some dairy plants for many

years to prepare low-sodium milk.

This procedure will provide a means for removing strontium 90 from milk that can be placed in

the dairy plant on a standby basis to be available

in case of an emergency.

Studies indicate that the procedure can remove

up to 90 percent of the strontium 90 in milk, and

that neither the mineral content nor the flavor is

appreciably altered.

Croplands Contaminated by Fallout

A nuclear attack on this country could contaminate huge areas of crop and rangelands with radioactive fallout. This contamination presents a

twofold problem: (1) the external exposure of

agricultural workers who attempt to enter heavily

contaminated areas — or to leave protective shelter

in such areas — to carry out farm duties ; and (2)

the. continued production of food without excessive internal radiation hazard to the population.

because succeeding crops grown on this soil would

take up some of the contamination.

The first hazard, external exposure, can be at

least partially combatted by observing maximum

work periods and denial times for outdoor activity

as suggested in table 1. In combatting the second

hazard, research workers are conducting studies

on methods of using contaminated soil for agricultural purposes or for decontaminating it.

Use of Contaminated Land

One of the first decisions to be made by agricultural leaders is how to use land contaminated

with fallout in order to continue to produce, indefinitely, a diet that permits the survival of the

people without exposing them to unacceptable internal radiation hazards. Table 5 has been devised

to serve as a guide for such decisions. Land contamination levels ( acid-soluble strontium 90 is assumed to be the long-term available strontium 90)

for each food group are based on the expected

strontium 90 content of the foods. Land contamination levels for denial of the use of the land for

the various food groups may be raised or lowered

as more information becomes available. Under

no circumstances should land be cultivated if the

farmer or rancher thereby will expose himself to

unacceptable levels of external radiation.

With the present average diet, Americans are

presumed to derive about two-fifths of their strontium 90 from dairy products, one-twentieth from

meat and eggs, and the remainder from plant

foods, including fruits, vegetables, and cereal

products. If uncontaminated milk and dairy

products are used, other foods from plant and animal sources can be accepted from land with 50

percent more contamination (as indicated m table

5) without exceeding the recommended limit for

strontium 90 in the total diet. If dairy products

and food from plant sources could be obtained

free of contamination, meat, eggs, and poultry

could be accepted from land with much higher

levels of contamination.

TABLE 5.—Guide for land usage, hosed on soil

contamination levels of acid-soluile strontium,

90 above which production of foods should he

limited, hy available calcium level of the soil'^

Contamination level per

square mile on soil with—

Product of land

Low Ca Medium High Ca

(2,000

lbs. /A.)

Ca

(6,000

Ibs./A.)

(20,000

Ibs./A.)

Curies Curies Curies

All foods in the diet, if they

all come from a contaminated area 3 10 30

All foods other than dairy

products, if they come from

a contaminated area, and

dairy products are free

from contamination 5 15 50

Meat, eggs, and poultry, if

all other foods are free

from contamination 60 200 600

This guide is based on a daily intake of 2,000 micromicrocuries of strontium 90.

The amount of contamination of crops with

strontium 90 depends markedly on the available

calcium content of the soil. For simplification of

the table, soils have been grouped as being low,

medium, or high in calcium content of the root

21
zone, which is considered to be about 1 foot for

most soils and crops. A sandy loam soil of pH

about 5 may contain 2,000 pounds or less of available calcium per acre. An average loam soil of

pH about 6 may contain 6,000 pounds of available

calcium jjer acre and \yould be considered medium.

A silt loam or silty clay loam of pH about 7 may

contain 20,000 pounds or more of available calcium per acre and would be considered high. The

available calcium contents of most agricultural

soils of the country are well known from soil test

data. (See map of the exchangeable calcium content of U.S. soil.)

A delay of several months or longer might

elapse before strontium 90 analyses could be made

on many contaminated soils. Therefore, it is recommended that temporary land use be based

on the standardized gamma radiation intensity

at H + 1. On low-, medium-, and high-calcium

soils, the recommended intensities, above which

crop production should be limited, are 100, 300,

and 1,000 roentgens per hour, respectively. The

purpose of the temporary limitations is to minimize in a practical manner the cultivation of land

that should be decontaminated before plowing.

The denial of land use, on the basis of strontium 90 analyses, is suggested for an indeñnite period unless modified by other measures. For example, r1t>r^r.r.fgr^r^.^fi^p »-f tlin oni^—hv SUCh

methods as surface soil removal and deep plowing

would increase the suitability of the land for agricultural production.

Contaminated land may be diverted to other

uses if the radiation level is too high for the original type of production. The diversion may mean

changing the species of crop grown on the land.

The quantity of strontium 90 absorbed could be

reduced by growing crops with low concentrations

of strontium and calcium in their edible tissues.

Potatoes, which contain about 10 milligrams of

calcium per 100 calories, are a particularly suitable crop in contrast to leafy vegetables, which

may contain from 100 to 1,000 milligrams of calcium per 100 calories. Corn would be another lowcalcium crop to consider. Sugar and oil crops

would also be suitable low-calcium crops for substitution on land too heavily contaminated to produce other foods. In general, crops producing

high-calcium foods should be grown on the less

contaminated land. However, since plants are a

source of calcium, the calcium content of diets containing only low-calcium crops would be low.

Unless alternative sources of dietary calcium were

provided, a change to low-calcium crops would

have obvious limitations.

Land formerly used for dairying can be diverted

EXCHANGEABLE CALCIUM CONTENT

^^4.^ OFU.S. SOIL

^^^^ÊÊÊÊ^UgÊmÊm^^^^^gff^-^y^.-yA ' ^^^^

\i . vlvB ^ ^^^ raS^^^S^^^

CALCIUM CONTENT

MiiliequivalenI Thousond lb,

per lOOg of soil per ocfe foot

Low Less than 5 Less than 4

Medium 5-15 4-!2

M High Over 15 Over 12

p ^^^^A

,]^i' MARCH I960 ^^B

22
to the production of beef or other meat. The

strontium retained by animals grazing contaminated pastures or eating contaminated hay goes

mostly into the bones or milk and not into the

meat. Consequently, the meat produced on contaminated land, within the limits set in table 5,

could be boned and used for food.

Byproducts of crops produced on contaminated

land, such as beet pulp, and cottonseed, linseed,

and soybean oil meals, should be used as animal

feeds only in accordance with the levels of contamination set in table 5. Milk produced on contaminated pastures could be used as feed for meat

production.

Another divereion might be to take the land out

of food production and use it for the production

of cotton fiber, flax, castorbeans, timber, or other

nonedible commodities. If the land is very heavily

contaminated, it might have to be taken out of

agricultural production for an indefinite period

or decontaminated.

Reducing Strontium 90 Uptake With

Soil Amendments

The addition of lime, gypsum, fertilizers, or

organic matter in practical amounts usually reduces the uptake of strontium 90 by less than 50

percent. Combinations of soil amendments and

tillage practices may reduce the uptake more than

would any single amendment. The best use of soil

amendments for maximum crop production is

often the same as their best use for reducing strontium 90 uptake.

The plant's need for the calcium of lime or gj'psum leads to the absorption of the chemically

similar element strontium. In soils low in exchangeable calcium, more strontium 90 will be

taken up by the plant. By liming acid soils, more

calcium is made available to the plant and less

strontium 90 will be absorbed. It is useful on

highly acid soils on which liming would be normally beneficial for other reasons. Gypsum would

be most useful on soils containing large quantities

of exchangeable sodium, which would normally

need gypsum regardless of the strontium 90 hazard. However, usually at best, the application

of lime can reduce the strontium uptake to only

about one-half of that from untreated soil.

For most soils and crops, it is recommended that

lime not be applied in excess of the amount of

calcium needed for maxinmm crop growth.

In the production of small cereal grains, the

addition of more calcium than is needed for optimal growth may be helpful in reducing the

strontium hazard, without reducing the quality or

quantity of the crop.

The application of lime to the surfaces of established pastures increases the calcium content of

the vegetation. An application rate of 2 tons of

lime per acre, for example, has lowered the ratio

of strontium to calcium in grass pastures by

two-thirds.

Farmers should use the amount of lime recommended by their county agents or State officials to

bring the soil approximately to pH 6.5. The

limestone should b© finely ground so that it will

react quickly with the soil. On plowed land, it

should be mixed thoroughly and as deeply into

the soil as possible. A surface application on

pastures growing in acid soil will also reduce the

strontium 90 content of forage, but it may not be

possible to use as much lime on pastures as in

plowed soil.

Best results from liming are possible on infertile or highly acid soils of the type found in the

humid eastern half of the United States. This

is because acid soils are low in available calcium,

and lime, a calcium compound, makes this essential nutrient available to plants. In low-calcium

soils, the plant's need for the calcium leads to

absorption of the similar element, strontium.

Thus, liming would have no appreciable effect on

strontium intake in good agricultural soils containing plenty of available calcium.

No one season is best for applying lime but, in

areas where the winter weather is cold enough to

harden the ground, f.^rmers often prefer to apply

lime when the ground will support heavy spreader

equipment easily.

Potassium fertilization of soils of relatively low

available potassium content at the rate of several

hundred pounds per acre can also reduce the uptake of strontium 90. However, the calcium uptake by the plants is also reduced by this practice.

Crop residues and manure applied at the rate of

20 tons per acre have reduced the uptake of strontium 90 by one-third.

Croplands Contaminated by Irrigation Water

Irrigation waters will not add much strontium 90 to agricultural land compared with direct

fallout on the cultivated soil or on crops themselves. Strontium 90 and other fallout isotopes

are considerably diluted in surface waters of any

appreciable depth. Most of the radioactive contaminants, including strontium 90, are readily

adsorbed by the soil of the banks and bottoms of

lakes and streams. They are subsequently adsorbed further by irrigation canal linings and

ditch banks. Any strontium remaining in the

water is subject to adsorption at the surface of

the cultivated soil with which the water first comes

into contact, and thereby is added to the surface

accumulation originating from direct fallout.

Direct contamination of crops by sprinkler irrigation with contaminated water pumped from

lakes, streams, or ponds would be a greater hazard, particularly from the contamination of leafy

23
EFFECT OF LIMING ACID SOIL

On Uptake of Strontium 90

M<.' :

FiGTJEE 9.—Addition of lime to contaminated acid soil dilutes the strontium 90 present and favors the uptake of

calcium instead of strontium 90 by plants.

vegetables. Irrigation water used for such crops, in radioactive contamination as acceptable drinkapplied with a sprinkler system, should be as low ing water.

Reclaiming Contaminated Land

Agricultural land should not be subjected to

drastic remedial measures such as decontamination until after it has been seriously contaminated

with strontium 90.

Neither special remedial measures nor unusual

modifications of normal practices should be introduced, however, until responsible authorities have

declared that a state of emergency exists, making

some kind of decontamination measures advantageous or necessary.

For instance, it might become necessary to reduce the radioactivity in small highly contaminated areas, or in large areas generally blanketed

by radioactive contamination. These situations

would require decontamination measures, drastic

modifications of usual practices, or a sequence of

24

smaller remedial factors at various successive links

in the food chain.

Decisions concerning the application of drastic

measures or of sequences of measures probably

never will be made easily. They must be based

on balancing medical assessments of probable

damage from radiation against the cost, along with

the resulting reduction in available food supplies,

and the economic and social dislocations.

The usefulness of a particular remedial measure depends primarily on how well is does the job

it's supposed to do. Various possible methods already have been experimentally investigated.

Others remain to be studied.

Field experiments have shown that when fallout is deposited on land where standing crops are
growing, no more than one-third of the deposit

can generally be removed from the land by harvesting the aboveground portion of the plants by

mowing.

Decontamination of soils is necessary primarily

for the removal of strontium 90. Other biologically significant fisson products either are taken

up from soils by plants in much smaller amounts

or have such short lives that decontamination is

not necessary. In zones of heavy strontium 90

deposition, stringent decontamination measures

will be necessary in order to reduce the strontium

90 content of the soil to a level acceptable for the

production of vegetables and milk. (These products absorb a greater percentage of the available

strontium 90 than do others.)

For the production of other crops, or in zones of

lighter strontium 90 deposition, it may be sufficient

to use less effective practices which reduce the

uptake of strontium 90 to a lesser degree. Obviously, heavily contaminated lands should be

placed in cultivation only when their use is absolutely necessary. In fact, the degree to which any

land is decontaminated must depend upon the

availability of manpower, fuel, and equipment,

and most important, upon the need for more cropland. The costly methods of decontamination

now known would be used only in limited areas of

intensively used croplands.

Decontamination by Removal of

Ground Cover and Crops

Decontamination by the removal of ground

cover is effective when the existing cover is thick

enough. Tests and experiments revealed that removal of heavy contaminated mulches, 5 tons per

acre, removed from 50 to 80 percent of the radioactivity even following irrigation. Kemoval of

lighter mulches, 2 tons per acre, removed from 30

to 50 percent. The cutting, rolling, and removal

of sod contaminated with fallout resulted in a reduction of radioactivity by over 90 percent.

Standing crops usually provide less complete

ground cover, especially when young, and their

harvest may remove only a small fraction of the

fallout. Contaminated crops could be disposed

of by harvesting and baling to reduce their bulk.

The bales must be stored where they will not

contaminate other foods. The workers should

wear respirators to avoid breathing the dust

created by these operations. Clothing should be

kept as clean as possible. Thorough washing of

the hands and face is necessary before eating.

Soil in greenhouses closed at the time of fallout

deposition would provide a limited source of uncontaminated soil.

Decontamination by Removal of

Surface Soil

The removal of surface soil is one of the most

effective methods of decontamination, but it would

be expensive, in many areas may not be applicable

and, with the procedures developed at this time,

not suitable for large areas. It might be useful

if small clean areas are needed to produce food for

survival of people.

The effectiveness of decontaminating surface

soil by scraping varies from being partially successful for rough land to being highly successful

for smooth land. Rough, freshly plowed surfaces

are difficult to decontaminate. Scraping off 2

inches of soil with a road grader may remove more

than 99 percent of the fallout from smooth soil,

but only 60 percent from rough soil. The latter

value is too low to justify the effort and expense.

Rough soil surfaces may be decontaminated more

completely by scraping off more soil or by repeating the scraping operation. Just as in harvesting, precautions against breathing dust and for

cleanliness will be necessary.

The safe disposal of contaminated surface soil

after removal is a serious problem. For the large

volumes of soil involved, the only practical places

for disposal appear to be pits in the center of small

fields or regularly spaced ditches across fields.

The pits or ditches would have to be protected

from erosion and should not be used for crop

production.

Other Methods of Decontaminating Soil

Several other methods of decontaminating soils

appear to be even less practical on a field scale.

Among them are leaching and cropping soils to

remove strontium 90. Leaching would require

extremely large amounts of water and calcium

salts or acids. In addition to removing strontium

90, plant nutrients would be leached out of the

root zone and would have to be replaced. Cropping, even with those crops known to take up

large amounts of calcimn and strontium, would

require more than 40 successive crops to achievo

90 percent decontamination.

Reclaiming Soil by Deep Plowing

Decontamination by deep plowing would be

aimed at placing the contaminated surface soil

18 inches or more below the surface — or below

the root zone of the plants that are to be grown.

In shallow-rooted crops, such as grasses and many

vegetables, deep plowing might reduce the uptake

of strontium 90 to about one-half of that under

normal cultivation. It will be most effective when

the freshly exposed surface soil has a high supply of calcium either naturally or by the addition

of lime or gj'psum. However, before the method

is used, the situation in the area, the need for the

crops which may be grown, and the possible alternatives should be carefully evaluated. Once

strontium 90 has been plowed under, not only by

deep plowing but also by normal tillage, future

removal is virtually impossible. Further, the

productivity of some soils may have been drastically reduced by the deep plowing.

25
Effects of Radiation on PlantKand Seeds.

The effects of radiation on plants and seeds differ ^Yidely, depending- upon age, moisture content,

state of metabolism, and for neutron irradiation,

chemical content. These factors may cause a tentó twenty-fold ditl'erence in radiation sensitivity

in different kinds of seeds.

Small seeded legumes appear to be very resistant to radiation, while rice, tomato, and cotton

are moderately resistant. Rye and barley are

moderately sensitive, while peanuts, soybeans, and

cowpeas are especially sensitive to injury from

gamma rays.

Sensitivity of seeds of different species varies so

greatly that seeds of pine or onions, for example,

may be completely killed by 1,000 rads of gamma

rays, while seeds of alfalfa or flax tolerate more

than 100 times this amount.

Total destruction of the ability of wheat, barley,

red clover, and millet to develop beyond the germination stage results from extremely high doses

of radiation of seeds. Post-germination development of wheat and barley will begin to be noticeably aflfected at a dose of about 5,000 rads and will

cease after a dose ten times that amount. Red

clover begins to lose its post-germination development ability at about 15,000 rads, and it ceases

altogether at 100,000 rads.

Radioactivity stored in leaves and stems is many

times greater than that found in seeds. For example, in wheat grown on artificially contaminated soil, the leaves showed 11,422 disintegrations from strontium 90 per second per gram,

compared with 638 in the grain. And most of this

was in the bran. In corn, the difference was even

more striking. About 4,683 counts were observed

in the leaves and only 18 in the grain. The same

story held true for cesium 137.

The high radioactivity found in the leaves compared with that in the seeds is in keeping with

the high calcium or ash content in the leaves compared with that in the seeds.

SUMMARY OF EFFECTS OF FALLOUT ON AGRICULTURE

An evaluation indicates that the total effect of

radioactive fallout on American agriculture in

case of nuclear attack would be serious. A series

of nuclear explosions across the Nation would

create hazards of severe radiation injury to farm

people and their livestock. Radioactive contamination of food, feed, and water would increase

the hazard. Residual contamination in the soil

would continue the problem over a long period of

time.

On the other hand, research is providing the

basic knowledge and specific means which can help

to lessen the seriousness of these widespread effects. Knowing the radiation level in his area,

the farmer can take several protective and remedial measures.

Shelter

The most vitally important measure for the

protection of farm families in time of emergency

is to seek shelter quickly and stay there as long as

recommended for the radiation intensity in the

area, making short trips for only the essential

jobs or supplies. The interval between a warning

of possible attack or the explosion and arrival of

fallout may provide the time to get the family and

livestock under cover. By taking advantage of

the protection provided by shelter, many families

and their livestock could escape injury or death.

Food, Feed, and Water

By protecting a sufficient quantity of food, feed,

and water fiom fresh fallout contamination, farm

families can prevent early internal radiation damage when the intensity is at high levels.

Maximum Work Times

Farmers who observe the maximum work times

suggested for alternating shelter and outdoors

work periods can gradually assume duties and yet

still take advantage of recommended protection

against radiation injury.

Food Decontamination

Some of the food that has been contaminated can

be made safe for consumption by following suggested methods for decontamination or by allowing time for sufficient decay of radioactivity.

Such food could be used for farm families or the

community, or salvaged for market.

Reclaiming the Soil

Some severely contaminated farmland could be

mamtamed in production by diverting it to its

safest use, or by decontamination through the

method best suited to the conditions.

These, then, are some of the safeguards available now against fallout damage. Research on

radioactive fallout is being continued. New

knowledge is expected to lead to improved methods

of protecting American agriculture against hazards of fallout in time of emergency.

26
GLOSSARY

(Definition of terms as they are used in this publication.)

ACCUMULATED DOSE: The total radiation

dose resulting from repeated or prolonged

exposure.

ACUTE EXPOSURE: Radiation exposure of

short duration.

ADSORPTION : The adhesion of one substance

to the surface of another.

AIR BURST : The explosion of a nuclear weapon

at such a height that the expanding fireball does

not touch the earth's surface.

ATMOSPHERE : The entire envelope of air surrounding the earth.

ATOM: The smallest particle of an element that

still retains the characteristics of that element.

ATTENUATION (RADIATION): The absorp

tion and reduction of radiation intensity as it

passes through any material.

BACKGROUND RADIATION : Nuclear radia

tion arising from within the body and from the

surroundings to which individuals are always

exposed in normal living. The main sources of

natural background radiation are potassium 40

in the body, potassium 40, thorium, uranium,

and radium present in rocks and soils, and cosmic rays.

BETA "RAY" (OR PARTICLE): A minute,

high speed particle with a negative charge and

originating in the nucleus of certain radioactive

elements. Physically the beta particle is identical with an electron moving at high velocity.

BLAST: The effect in air of the liberation of a

large amount of energy in a short interval of

time within a limited space. The liberation of

this energy is accompanied by a great increase

in temperature creating extremely hot gases

from the products of an explosion. These gases

move outward rapidly, pushing away the surrounding air with great force, and cause the

destructive effects of an explosion.

BRIEF EXPOSURE : Exposure witliin the first

96 hours.

CELL: The fundamental unit of structure and

function in plant and animal organisms.

CONTAMINATION (RADIOACTIVE FALLOUT) : The deposit of radioactive material on

the surface of land, structures, objects, human

beings, animals, plants—entire areas—following a nuclear explosion. Plants may also be

further contaminated by absorbing radioactive

material from contaminated soil or water; and

animal products through the animal's consumption of contaminated feed and water.

COSMIC RAY: Any of the rays of extremely

high energy and penetrating power produced,

it is believed, by electric action in interstellar

space (beyond the earth's atmosphere). They

bombard the earth from all directions.

CURIE : A unit for measuring radioactivity, equal

to that produced by a gram of radium. (Microcurie is one-millionth of a curie, and a micromicrocurie or picocurie is one-millionth of a

millionth of a curie.)

DECAY (RADIOACTIVE) : The decrease in activity of any radioactive material with the passage of time. See^HALF-LIFE.

DENIAL TIME: The period of time persons

would be prohibited from entering a contaminated area or leaving shelter in such an area because of radiation intensity. Also, the period of

time croplands would be prohibited from use for

designated agricultural products because of

radioactive contamination, or milk prohibited

from human consumption because of radioiodine

content.

DISCRIMINATION: The natural discrimination against one chemical element in favor of

another by the biological systems of plants, animals, and man. An example is the discrimination against strontium in favor of calcium.

DOSE: A (total or accumulated) quantity of

ionizing (or nuclear) radiation. The term dose

is often used in the sense of the exposure dose,

expressed in roentgens, which is the measure of

the total amount of ionization that the quantity

of radiation could produce in air. Tliis should

be distinguished from the absorbed dose, given

in reps or rads, which represents the energy

absorbed from the radiation per gram of specified body tissue. Further, the biological dose,

in rems, is a measure of the biological effectiveness of the radiation exposure. See RAD,

ROENTGEN.

DOSE RATE: The amount of dose of ionizing

radiation to which an individual is exposed per

unit of time (hour, day, week, or month). It

is usually expressed as the number of roentgens

per hour. The dose rate is also commonly used

to indicate the level of radiation intensity in a

contaminated area.

ELECTRON: A very small particle of matter

carrying a negative charge. Electrons are present in all atoms surrounding the nucleus. In a

neutral atom their number is equal to the number of positive charges (or protons) in the particular nucleus.

ELEMENT: One of the distinct, basic varieties

of matter which, individually or in combination,

have unique chemical characteristics. Ninetytwo naturally occurring elements have been

identified in nature and about 10 others have

been produced as a result of nuclear reactions.

EQUIVALENT RESIDUAL DOSE: The accumulated exposure dose of gamma radiation

corrected for such recovery as has occurred at

any particular time.

27
FALLOUT : Dustlike particles of radioactive matter created by a nuclear explosion. The term is

also used to describe the process of the fall back

to earth of the contaminated particles from the

bomb cloud.

FIREBALL: The luminous sphere of hot gases

which forms a fraction of a second after a nuclear explosion and immediately starts to expand and cool.

FISSION (NUCLEAR FISSION) : The process in which the nucleus of an atom of a heavy

element; for example, uranium, splits into (generally) two nuclei of lighter elements, with the

release of large amounts of energy.

FISSION PRODUCTS : A general term for the

complex mixture of radioactive substances produced as a result of nuclear fission. (The mixture contains over 200 diiïerent isotopes of over

35 elements.)

FOOD CHAIN: The route of nutrients from the

soil through plants and animals, and through

the biological system of man as human nutrition.

GAMMA RAYS: Electromagnetic radiation of

high energy emitted by the nucleus of an atom.

These rays accompany many nuclear ]-eactions

including nuclear fission. Physically, gamma

rays are identical with X-rays. The only essential difference is that X-rays do not originate

in the nucleus of an atom.

GEIGER COUNTER: An instrument for measuring radiation rate. As usually constructed it

is a highly sensitive instiiunent with a very

short range of measurement that would be useful only for monitoring low levels of intensity

such as for food, water, and personnel.

GENETICS : The branch of biology dealing with

heredity and variations from one generation to

another.

HALF-LIFE : Time required for a radioactive

substance to lose 50 percent of its radioacti^-ity.

Decrease of radioactivity is usually referred to

as decay.

INITIAL RADIATION: Nuclear radiation

emitted from the fireball and atomic cloud during the first minute after a nuclear explosion.

INTENSITY (RADIATION) : The term is used

loosely to express exposure dose rate of radiation

at a given location. For example, the intensity

of radiation at the location could be expressed in

the number of roentgens per hour measured by

an appropriate instrument at that point.

ION: An electrically charged atom or molecule,

either positive or negative.

lONIZATION: The process by which a neutral

atom or molecule matter receives an electrical

charge, either positive or negative.

IONIZING RADIATION: Radiation capable of

producing ions either directly or indirectly as

It passes through matter. Passage of ionized

radiation through living cells causes biological

damage.

28

IRRADIATI0i*4Exposu£ßJ:u_xadiatiear

ISOTOPES: FoiTOsof the same element which

usually have identical chemical properties but

which differ in their atomic masses (because

they have a different number of neutrons in

their respective nuclei). They may be stable

(nonradioactive) or they may be radioactive.

KILOTON NUCLEAR BOMB: A nuclear bomb

which produces the same amount of energy as

1,000 tons of TNT.

MAXIMUM PERMISSIBLE EXPOSURE : As

applied to postattack emergency operations, the

total amount of ionizing radiation exposure

which it is believed a normal person may receive

without the harmful effects outweighing potential benefits.

MEGATON NUCLEAR BOMB: A nuclear

bomb which produces the same amoimt of

energy as 1,000,000 tons or 1,000 kilotons of

TNT.

MIDLETHAL DOSE (MEDIAN LETHAL

DOSE, OR MLD) : The amount of ionizing radiation over the entire body which is expected

would be fatal to 50 percent of a large group

of a given species of living creatures or organisms within 30 days. It is commonly (although

not universally) accepted that 450 roentgens

is the midlethal dose for human beings.

MOLECULE: The smallest group of atoms that

can exist isolated from other like groups, as in a

gas or in a solution. The molecule of a compound contains more than one kind of atom.

The molecule of an element consists of one or

more like atoms.

NEUTRON: A neutral particle of matter (with

no electrical charge) present in all atomic nuclei except those of ordinary hydrogen.

Neutrons are required to initiate the fission process, and large numbers of neutrons are produced

in nuclear explosions. The short path and life

of neutrons from a detonation limit their

damage to initial radiation at the time of the

explosion, and they do not contribute to residual

fallout radiation hazard. Neutrons present

little hazard ouside the area of heavy blast

damage.

NUCLEAR RADIATION: Radiation emitted

from atomic nuclei in various nuclear processes. The types of radiation discussed in this

publication are beta rays and gamma rays.

(Other radiations important in the results of

nuclear explosions are alpha rays and neutrons.) All these nuclear radiations are, or result in ionizing radiations, but the reverse is not

true. For example. X-rays are ionizing radiations, but they are not nuclear radiations because they do not originate in the nucleus of an

atom. See—IONIZING RADIATION.

NUCLEAR WEAPON (OR BOMB) : A general

name given to any weapon in which the explosion results from the energy released by reactions involving the nuclei of atoms. Thus,
both atomic bombs and hydrogen bombs are in

fact nuclear weapons, and the tei-m is used to

inchide both types in this publication.

NUCLEUS (OR ATOMIC NUCLEUS): Tlie

core of an atom that carries most of the mass

and the total positive electrical charge. AH

atomic nuclei (except ordinaiy hydrogen) contain both protons and neutrons (positively

charged and neutral particles). The electrons

(negatively charged particles) of ai\ atom are

outside the nucleus.

PROTECTION FACTOR: The relative reduction in the amount of radiation that Avould be

received by a person in a protected location,

compared with the amount he would receive if

he were unprotected.

PROTON : A particle of matter carrying a positive charge. It is identical physically .with the

nucleus of the ordinai-y hydrogen atom. All

atomic nuclei contain one or more protons.

RAD : A unit for measuring an absorbed dose of

radiation.

RADIATION: See—NUCLEAR RADIATION.

RADIATION SICKNESS: A disease resulting

from excessive exposure of the entire (or a large

part) of the body to ionizing radiation. Some

early symptoms are nausea, vomiting, and diarrhea, which may be followed by loss of hair,

hemorrhage, inflammation of the mouth and

throat, and general loss of energy. In severe

cases, where the radiation exposure has been

relatively large, death may occur within 2 to 4

weeks. Those who survive 6 weeks after the

receipt of a single dose of radiation may generally be expected to recover.

RADIOACTIVITY : The spontaneous disintegration or nuclear change of certain atoms in which

energj' is released. The process is accompanied

by the emission of one or more types of radiation, such as beta and gamma rays.

RADIOIODINE (RADIOACTIVE IODINE):

Iodine in which the nuclei of the atoms emit

radiations.

RADIOISOTOPE : See^ISOTOPES.

RADIOSTRONTIUM (RADIOACTIVE

STRONTIUM) : Strontium in which the nuclei

of the atoms emit radiations.

RESIDUAL RADIATION: Nuclear radiation,

clnefly beta and gamma rays, which persists

longer than 1 minute following a nuclear explosion. The radiation is emitted mainly by

the ñssion products and other bomb residues

in the fallout.

ROENTGEN: A unit for measuring a radiation

exposure dose.

SHELTER (FALLOUT): A specially constructed refuge, or the use of normal buildings

or materials primarily for the purpose of protecting people, livestock, or other living organisms from the gamma radiation resulting from

fallout.

SHIELDING : Any material or obstruction which

absorbs radiation and thus helps to protect

people and livestock from the effects of radioactive fallout. A considerable thickness of material of high density may be needed.

STRATOSPHERE : The part, of the earth's atmosphere extending from the troposphere (approximately 7 miles above the earth) to altitudes as great as 45 to 50 miles. (See—TROPOSPHERE.)

SURFACE BURST: The explosion of a nuclear

weapon at the surface of the earth, or at a

height above the surface close enough for the

fireball to touch the land or water. The effect

of fallout is most serious following a surface

burst.

TROPOSPHERE : The lower part of the earth's

atmosphere, characterized by formation of

clouds and precipitation. Typical upper limits

of the troposphere are about 6 miles in the polar

regions and 9 to 12 miles near the equator.

(See—STRATOSPHERE.)

UNDERGROUND BURST: The explosion of a

nuclear weapon with its center beneath the

surface of the ground.

UNDERWATER BURST: The explosion of a

nuclear weapon with its center beneath the surface of the water.

29
APPENDIX A

Measurement of Fallout Radiation

Monitoring is essential to determine the degree

of contamination of personnel, objects, facilities,

food and water, as well as to determine where in

the general environment decontamination is required and the effectiveness of decontamination

measures. Monitoring senñces and information

must be available to fanners and agricultural officials to help them determine their ability to conduct essential fami activities.

In agreement with national defense plans, programs,"and operations of the Department of Defense, under Executive Order No. 10952, the

Department of Agriculture is responsible for

developing plans for a national program, directing Federal activities, and furnishing technical

guidance to State and local authorities concerning

protective measures, treatment, and handling of

the following, any of which have been exposed to

or affected bj' radiation :

(1) Livestock, including poultry.

(2) Agricultural commodities on farms or

ranches.

(3) Agricultural lands.

(4) Forest lands.

(5) Water for agricultural purposes.

(6) Äleat and meat products, poultry and

poulti-y products in establishments mider the continuous inspection of the U.S. Department of

Agriculture.

(7) Agricultural commodities and products

owned by the Commodity Credit Corporation or

by the Secretary.

The intensity of gamma radiation from fallout

at any given time and location is expressed in

terms of a unit of measurement called a "roentgen." It is an accepted unit for measuring radiation in air, just as a calorie for heat or a kilowatt

hour for electricity. The roentgen is used in two

different connotations: (1) Total accumulated

radiation exposure is expressed merely as so many

roentgens, and (2) the rate of radiation exposure

given off by fallout or any other nuclear radiation

source is expressed as roentgens per luiit of time

(per hour, minute, or second.)

The human senses do not detect ionizing radiation. Special instruments have been developed

for the detection and measurement of various nuclear radiations.

These devices can be divided into rate meters

and dosimeters:

30

Rate meters are used to measure radiation

rates in an area. They are basically reconnaissance instruments to measure the radiation dose

rates across an area or near items that might be

contaminated. Such measurements are essential

as a basis for evaluating potential occupancy of

areas, utilization of. materials, or need for decontamination. They might be used in three ways:

(a) For field station monitoring; scheduled

measuring and reporting of dose rates at a predetermined point outside a sheltered location.

(b) For aerial surveys to enable general estimation of radiation levels over a wide area.

(c) For detailed monitoring of areas, facilities, objects, and materials after radioactive decay

has reduced dose rates to a level permitting extended field activity.

The Office of Civil Defense, Department of Defense, has developed monitoring instruments or

rate meters to be used for survey purposes in the

event of emergency operations. Examples of instruments having the widest application are :

(a) The low-range beta-gamma survey meter

(CD V-700) is a Geiger counter type. It is a

highly sensitive instrument and is suitable for

emergency monitoring of food, water, and personnel. It has a measurement range from 0 to 50 milliroentgens per hour. (A milliroentgen is onethousandth of a roentgen.) Such a short range

of measurement would be of little use in an area

with significant contamination, since a relatively

low level of radioactivity would drive the indicator needle off the scale unless the Geiger tube and

sample were exposed in an adequate shield.

(b) A medium-range gamma survey meter (CD

V-710)^ would be most widely useful for general

radiological monitoring following attack. The

measurement range is from 0 to 50 roentgens per

hour. The instrument is designed for ground survey where the radiation levels would be expected

to change relatively slowly. Until a special instrument is available, it will be used for aerial survey.

(c) A high-range beta-gamma survey meter

(CD V-720) would be required in areas where

' In future procurement of instruments by the OflSce of

Civil Defense, the CD V-710 survey meter will be replaced

by a CD V-TIS, Radiological Survey Meter, gamma only,

0-0.5, 0-5, 0-50, 0-500 roentgens per hour.
FiGTiBE 10. A Geiger counter is a monitoring device used to detect and measure radioactivity. Its range of measurement is very small, but in time of emergency it would be useful for monitoring food, water, and personnel.

contamination levels are extremely high and for

making high level beta radiation measurements.

This instrument has a measurement range from

0 to 500 roentgens per hour.

Dosimeters are used to measure accumulated

dose of radiation in an area or the accumulated

exposure of people and livestock. Self-mdicating

dosimeters have been developed. Two examples

are:

(a) CD V-730, with a measurement range

from 0 to 20 roentgens.

(b) CD V-Y40,* with a measurement range

from 0 to 100 roentgens.

As part of the Nation's preparedness program,

the Federal Government is assisting the States and

their political subdivisions to develop systems for

* In future procurement of instruments by the OfBce

of Civil Defense, the CD V-740 dosimeter will be replaced

by a CD V-742, Radiological Dosimeter, self-reading,

gamma only, 0-200 roentgens.

31
}

FIGURE 11.—A medium-range gamma survey meter (above) would be generally used to determine the intensity of

radioactivity at ground level following an attack.

postattack radiological monitoring and reporting.

Kits of instruments are made available to the

States when monitors are trained and qualified for

emergency operations from slieltered locations.

Financial assistance is also given for the procurement of some types of communications equipment

for civil defense purposes.

Information resulting from plotting, analysis,

and evaluation of reported radiological data will

be used as a basis for the control of radiation exposure during emergency operations, and for

warning and instruction of the public.

In the event of a nuclear attack, States and

local civil defense organizations M-ould be responsible for scheduled periodic radiological monitoring and reporting. As information on intensity

32

and location of radiation becomes available, it

will be broadcast on radio stations.

Details of local, State, and national radiological

defense systems are beyond the scope of this report

and are described in the Office of Civil Defense

publications listed under "Publications and

Films," page 140.

As a supplement to organized Federal, State,

and local monitoring systems, every home and

community shelter should have an instrument to

measure radiation dose rate—a ratemeter. In the

event of a nuclear attack, such an instrument

would provide information that will help the user

determine the degree of fallout danger he faces,

and help him make logical decisions for greater
FiGUBE 12.—A dosimeter measures the accumulated dosage of radioactivity.

safety. For example, a citizen's radiation instrument should help the user determine when to take

shelter, when to leave the shelter, and how long

it would be advisable to remain in an improtected

area. The instrument also should be of value in

locating that portion of the home or protective

structure that offers the best protection from

fallout.

In addition to a ratemeter, a dosimeter would

be useful for keeping track of accumulated radiation exposure over a long period. A reasonable

range for a citizen dosimeter is from 0 to 600

roentgens.

Instruments having all of the essential and most

of the desirable characteristics described are commercially available. Other instruments, designed

on the basis of these characteristics, are being

developed.

33
APPENDIX B

Protection Factors

TABLE Q.—Descríption of shelter categories with

associated protection and attenuation factors ^

Shelter

cate- I Protection factor i

gory

1,000 or greater

(better than

0.001).

250 to 1,000

(0.004 to

0.001).

50 to 250 (0.02

to 0.004).

D 10 to 50 (0.1 to

0.02).

2 to 10 (0.5 to

0.1).

2 or less (0.5 or

poorer).

Common examples *

OCD underground shelters.

Subbasement of multistory

buildings.

Underground installations

(mines, tunnels, etc.).

OCD basement fallout shelters

(heavy masonry residences).

Basements (without exposed

walls) of multistory buildings.

Central areas of upper floors

(excluding top 3 floors) of

high-rise buildings ' with

heavy floors and exterior

walls.

OCD basement fallout shelters

(frame and brick veneer

residences).

Central areas of basements

(with partially exposed walls)

of multistory buildings.

Central areas of upper floors

(excluding top floor) of multistory buildings with heavy

floors and exterior walls.

Basements (without exposed

walls) of small 1- or 2-story

buildings.

Central areas of upper floors

(excluding top floor) of multistory buildings with light

floors and exterior walls.

Basements (partially exposed)

of small 1- or 2-story buildings.

Central areas on ground floors

in 1- or 2-story buildings

with heavy masonry walls.

Aboveground areas of light

residential structures.

' This term expresses the relative reduction in the

amount of radiation that would be received by a person in

a protected location, compared with the amount he would

receive if he were unprotected. The reciprocal of the

protection factor is called the attenuation factor.

' These examples refer to isolated structures.

' For the purposes of this example, "high-rise" buildings

are those greater than about 10 stories; multistory buildings are those from 3 up to about 10 stories.

Source: Adapted from Appendix 2, Annex 10, National

Shelter Plan NP 10-2, OCDM, May 1960.

TABLE 7.—Types of buildings that will provide

approximately the stated attenuation for loosehoused livestock and poultry ^

Item

Attenuation

factor

0. 0125

025

05

075

d.

Types of buildings

a. Large barn (50' X 80' minimum);

full bank on 3 sides; heavy solid

concrete or stone wall on fourth side;

few doors and windows; 6 feet

baled hay ^ above basement.

a. Large barn; half bank; solid concrete

or stone foundation; few doors;

windows above animals' backs; over

12 feet baled hay above.

a. Large barn; half bank, cinder block

foundation; windows above cattle;

12 feet baled hay.

b. Large barn; gambrel roof; two-story

on cinder blocks; no windows and few

doors; full of baled hay (gambrel

roofs retain less fallout than do gable

roofs).

As in la, empty of hay.

a. As in 2a, empty of hay.

b. Full cinder block ground floor; 25

feet baled hay.

a. Large barn; fuU masonry ground

floor; no windows; empty.

b. Large barn; one-half bank; cinderblock foundation; 12 feet baled hay.

a. Large barn; full frame; no foundation

above floor; 25 feet baled hay.

b. Hog house; solid concrete walls, no

windows; metal roof.

c. Poultry house; first floor only of large

multistory masonry construction;

windows 3 feet above floor.

Medium-sized frame barns; no foundation above floor; 25 feet baled hay.

Very large frame barns; two-story;

2-foot foundations; few windows;

empty of hay.

Full cinder-block barns if empty;

cinder-block hog barns with metal

roof.

Large frame barn; one-half bank on

cinder block; empty of hay.

Very large, all frame, two-story barn;

empty of hay.

See footnotes at end of table.

34
TABLíB 7.—Types of huildings that will provide

approximately the stated attemtation for loosehoused livestock and poultry—Continued

Item

Attenuation

factor

10

Types of buildings

b. Very large quonset-type barn; full of

confined stock.

c. Larger sheep sheds, hog houses, and

very large one-floor poultry houses;

limited openings; full of confined

stock.

a. Medium-sized barns with haylofts;

frame; few windows; low foundations;

empty.

b. Barns in items 7 and 8 with asphalt

or flatter roofs with high fallout

retention.

c. Cinder block or tile low poultry

houses and hog houses, if asphalt roof

or other retentive types.

d. Larger one-floor poultry houses with

Umited openings.

e. Midfloors of multistory poultry

houses, including large frame barns

converted to poultry houses.

f. Any farm building giving shelter

equivalent to first floor of a two-story

frame dwelling with normal windows.

a. Very large "pole sheds," open on low

side ; animals confined under roof.

b. Large poultry houses; one floor; numerous openings that can be covered

with canvas.

c. Smaller poultry houses with few

windows.

TABLíB 7.—Types of buildings that will provide

approximately the stated attenuation for loosehoused livestock and poultry—Continued

Item

11

12

13

14

Attenuation

factor

.9

1.0

Types of buildings

Smaller poultry houses with considerable openings.

Sheds on side of larger buildings,

considerable openings; stock confined.

Top floor of barn converted to multiple-floor poultry house.

Smaller sheds with large side open;

animals confined.

Smaller poultry houses and shelters;

many openings.

Open sheds; animals free to run in

shed or adjacent small lot only.

No significant shelter-free running or

grazing animals. These values assume loose housing of animals or

poultry; animals confined in stalls

near doors and low windows would

have far less protection than would

those in the most protected areas in

the building.

1 Based on calculations and guides provided by Neil

FitzSimons, Office of Civil Defense, Department of

Defense.

2 As shielding material, 6 feet of hay are equivalent to 1

foot of water or about 7 inches of earth.

35
APPENDIX C

40 Cow Dairy Barn and Family Fallout Shelter

Protection for highly valued livestock should

be considered along with the fallout shelter for

the rural family. In many respects, fallout protection requires"structural characteristics opposite

of those found in efficient farm buildings. This

plan is a compromise between a relatively high

degree of protection for livestock, and a reasonably efficient dairy operation under normal

conditions.

All exterior walls should be at least 12 inches

thick and of a dense material such as poured concrete, stone, concrete block or brick with cores

filled with mortar or earth, or pressure treated

wood with space between filled with sand. Family

shelter exterior walls should conform to standards

of the Office of Civil Defense, Department of

Defense.

The main features of the plan are :

(1) The family shelter is built-in. This gives

construction economy over a separate family shelter, and allows the dairy operator to continue work

during a fallout emergency without exposure to

outside radiation levels.

(2) A thick layer of earth is placed overhead

as a shield against fallout on the roof.

(S) Mechanical feeding reduces operator time

outside the family shelter, and all stored feed ia

manually accessible inside the barn.

GASOLINE SroHAGE

WALL -j

SmAW ^ HAY STORAGE

FE£D\ BIN3

LI TTER AL LEY

A/J? //t/TAATA FEED ALLEY

•"1 f

IT T

n~T''

^

LITTESÍ ALLEY

éíAj:LG_E^^_

PLAN

^SECTION

FIGURE 13.—40 cow dairy barn and family fallout shelter.

36
(•4) Other livestock could be temporarily

housed, fed, and watered inside.

(5) Stored hay and straw are placed for shielding effect. Outside doors are to be temporarily

shielded with water-soaked bales.

(6) The ventilating air is filtered and flow rate

is adjustable. Air to the family shelter can be

supplied by direct duct or by leakage from the

barn.

(7) An auxiliary generator assures electric

power, although it is anticipated that many areas

will not lose commercial power.

(8) The water supply pump is inside the bam.

Tanks not shown on the plan, are covered and

vented several feet above ground to exclude settling fallout.

A rough estimate of protection from radioactive

fallout is given by the weight of all materials between the fallout and the shielded space. Below

ground construction and earth banks increase the

protection of a concrete wall several times. If

stored forage is relied upon for shielding, a thickness of several feet should be maintained. Ordinary glass windows and wood doors have very

little shielding value, and must be blocked with

more material. A minimum area of glass block

serves as windows in the plan, and local milk

sanitarians should be consulted for lighting

requirements.

bhielding values of the structure are evaluated

according to "Fallout Shelter Surveys: Guide for

Architects and Engineers," National Plan Appendix Series, NP-10-2. The percentage of outside

radiation entering the structure increases greatly

if essential construction features are omitted.

Percentage o/

outside radiation

Family

Construction Barn shelter

As shown on plan 0.9

Doors not shielded with wet hay bales 3. 0

Overhead sand replaced by baled hay 10. 7

Glass block replaced by ordinary windows- 1. 3

0.3

.3

3.7

.4

TRENCH-TYPE SHELTER ARRANGEMENTS

(A, B, C, D) Roofs for Trench-Type Fallout Shelters

Trench silos can be converted to fallout shelters by adding an overhead earth shield and a

baffled entrance. The long, narrow shape facilitates bridging to support overhead shielding and

minimizes radiation penetration through openings. A 2-foot thickness of earth overhead and

entrances as shown on the sketches, give a radiation reduction factor of 0.0023. This is a protection factor of over 400. It is worthwhile to note

that a 1-foot thickness of earth will admit 13 times

as much radiation as a 2-footthickness.

(E, F) Fallout Protection in Buildings

A building constructed as in the sketches would

provide a reduction factor of about 0.025. Necessary conditions for obtaining this protection include walls banked with earth to sill level,

protected stock kept below sill level, and tightly

closed doors. Further improvement in shelter

value can be accomplished by reducing or eliminating windows and doors and by full earth banks

around outside walls.

With 2 feet of earth overhead, very little radiation would penetrate the roof. With only 1 foot

of earth, fallout on the roof would be the main

source of radiation inside and flushing would be

necessary to obtain the stated reduction factor. A

flushing system must provide for rapid runoff

away from the building to avoid pile-up of fallout

around the walls.

A hay mow with 10 feet of baled hay will give

overhead shielding about equal to 1 foot of earth.

Also, the steep gambrel roof will retain less fallout. Hay mows and other feed storage spaces

should be tightly weathersealed to prevent

contamination.

37
A.ARCHED

Commercial Metal Components

B. PITCHED

Three-Hinged Arcti or Trussed Rotters

C. FLAT

Logs,Wire Mesti and Straw

D. FLAT

Posts, Beoms and Joists

ROOFS FOR TRENCH-TYPE FALLOUT SHELTERS

CROSS SECTIONS SHOWN ON TYPICAL CONCRETE-LINED SILOS

A 2-Foot Loyer of Eorth Will Provide

a Protection Factor of About 400 and

Will Weigh from 200 to 250 Lbs. Per

Square Foot of Roof Area.

RIDGE SPRINKLER PIPE

FOR FLUSHING ROOF

It is Important that the Roof Structure

be Carefully Designed to Safely Support

all Live and Dead Loads.

E. ONE-STORY BUILDING

The Depth of the Sard or Earth Fill Will

be Limited by the Strength of the Ceiling

Structure.

Supply Generous Quantities of Water for

Decontaminating. Drain Contaminated

Water Away for the Lots.

F BANK-TYPE DAIRY BARN

A 15 Foot Depth of Tightly Boled Hay Will

Provide Shielding About Equal to o 2-Foot

Layer of Earth, but the Depth Should be

Reduced if Necessary to Avoid Over-loading

the Mow Floor.

FALLOUT PROTECTION IN BUILDINGS

Bank Earth up to Sill Height on all Exposed

Walls and Protect Against Erosion.

Windows and Doors May be Closed With

Concrete Blocks or Sondbogs.

In New Construction, Openings Should be Kept

to a Minimum, Window Sills Should be High

and the Mow Floor or Ceiling Structure Must

be Designed to Support the Heavy Load of

Shielding Material. A Concrete Mow Floor

Increases Shielding.

38
ENTRANCE, DRAIN

AND AIR INTAKE

EXHAUST VENT

STACK OVER

>«ííí;'^V;í,*':>VA.., ..

CATTLE

I

-7

SILO

-BALED HAY,

UP TO ROOF

REMOVABLE

WALL SECTION

SILO

-SILAGE PACKED $,

MOUNDED TO DRAIN

TO EACH SIDE

L-SHAPED

VENT 4

ESCAPE

--EXTEND ROOF

OVER LOWER

END OF SILO

VENT Í. J

ESCAPE^

I I ^^—EXHAUST VENT

' STACK OVER

- FAMILY

CATTLE

^,

SANDBAGS OR

EARTH FILLED

BULKHEAD

ENTRANCE, DRAIN

AND AIR INTAKE

Zll

FAMILY

znCATTLE

BALED HAY,

>v UP TO ROOF -,

EXHAUST VENT

STACK OVER

SILO

-ENTRANCE, DRAIN

AND AIR INTAKE

IN-LINE PARALLEL

Silos to be Sealed with Plastic Sheeting and Covered

with Sowdusf or other Suitable Ballast. All other

Areas tobe Roofed and Covered with Two Feet of

Eorth Sodded or otherwise Protected from Erosion.

TRENCH-TYPE SHELTER ARRANGEMENTS

39
PUBLICATIONS AND FILMS

Publications

Office of Civil Defense, Department of Defense

BULLETINS :

Permissible Emergency Levels of Radioactivity

in Water and Food (September 1955).

Emergency Measurements of Radioactivity in

Food and "Water (December 1952).

Radiation Physics and Bomb Phenomenology

(Rev. Jmie 1959).

Radiological Defense Planning and Operational

Guide.

Fallout Protection.

Family Shelter Designs.

Office of Emergency Planning

NP-10-1—Fallout Shelter Surveys, Guide for

Executives.

NP-10-2—Fallout Shelter Surveys, Guide for

Architects and Engineers.

U.S. Atomic Energy Commission

The Eiïects of Nuclear Weapons. U.S. Department of Defense and U.S. Atomic Energy Commission (April 1962).

U.S. Department of Agriculture

Farmers' Bulletin 2107—Defense Against Radioactive Fallout on the Farm (Revised April

1961).

Home and Garden Bulletin No. 77—Family Food

Stockpile for Survival (August 1961).

USDA Radiological Training Manual (Rev. July

1961).

Films

U.S. Department of Agriculture

Fallout and Agriculture. Color; time: 23 min.

Released 1960. (Prints available from the Motion Picture Service, Office of Information, U.S.

Department of Agriculture, AA^ashington 25,

D.C., and Film Service Libraries of all State

Colleges of Agriculture.)

Office of Civil Defense, Department of Defense

The following films are CURRENT and may

be obtained from your nearest LT.S. Army Central

Film and Equipment Exchange :

Civil Defense in Schools

Crisis

Emergency Hospital

Fallout

House in the Middle, The (6I/2 mm.)

House in the Middle, The ( 12 min.)

In-^asible Enemy, The

Lifeline of the Nation

No Time To Lose

Operation Cue (Short, silent version)

Operation Cue (Long, silent version)

Operation Cue—Revised (Color, sound)

Radiological Defense

Rehearsal for Disaster

Ten for Sur^-ival :

#1—Enter the Nuclear Age

#2—Knowledge Is Survival

#3—Biography of a Disaster #1

#4—Biography of a Disaster #2

#5—Fact and Fable

#7—The Unseen Enemy

#8—Radiation and the Body

The following films are current, but are to be

used for TRAINING ONLY:

Mission Fallout

Nerve Gas Casualties and Their Treatment

Trapped

A new catalog is now being prepared which will

contain detailed information on content, type, and

prices of all current OCD films. AAHien this publication is available, its release will be announced

through an Information Bulletin.

SERVICE AREAS OF U.S. ARMY CENTRAL FILM AND EQUIPMENT

EXCHANGES

First U.S. Army Central Film and Equipment

Exchange, Governors Island, New York 4,

N.Y.

Connecticut New Jersey

Maine New York

Massachusetts Rhode Island

New Hampshire Vermont

Second U.S. Army Central Film and Equipment

Exchange, Ft. George G. Meade, Md.

Delaware Pennsylvania

Kentucky Virginia

Maryland West Virginia

Ohio

40
Third U.S. Army Central Film and Equipment

Exchange, Ft. McPherson, Ga.

Alabama North Carolina

Florida South Carolina

Georgia Tennessee

Mississippi

Fourth U.S. Army Central Film and Equipment

Exchange, Ft. Sam Houston, Tex.

Arkansas Oklahoma

Louisiana Texas

New Mexico

Fifth U.S. Army Central Film and Equipment

Exchange, Ft. Sheridan, 111.

Colorado Missouri

Illinois Nebraska

Indiana North Dakota

Iowa South Dakota

Kansas Wisconsin

Michigan Wyoming

Mimiesota

Sixth U.S. Army Central Film and Equipment

Exchange, Presidio of San Francisco, San

Francisco, Calif.

Arizona Idaho

California Montana

Nevada

Oregon

Utah

Washington

Military District of Washington, Central Film

and Equipment Exchange, Ft. Myer, Va.

District of Columbia, Greater Washington,

D.C., Area. (All requests from Maryland

and Virginia outside this area should be sent

to Second U.S. Army Central Film and

Equipment Exchange as indicated above.)

U.S. Army Caribbean, Central Film and Equipment Exchange, Corozal, C.Z.

Canal Zone

VirgÍ2i Islands

U.S. Army Forces Antilles, Central Film and

Equipment Exchange, Ft. Brooke, P.R.

Puerto Rico

U.S. Army Pacific, Central Film and Equipment

Exchange, Schofield Barracks, Hawaii

Hawaii

Guam

U.S. Army Film and Equipment Exchange,

Fort Richardson, Alaska

Alaska

U.S. GOVERNMENT PRINTING OFFICE. 1962 O—644700

41