Radiation Hazards and
Sources of Radiation
Elements such as thorium, uranium, radium, RN-222,
and K-40 are naturally occurring radioactive elements
that can be found in our everyday lives.
These elements can be found in:
– rocks, soil and building materials
– food and water
Some sources are a result of ground nuclear testing,
which is not naturally occurring.
Cosmic and Atmospheric
Cosmic and atmospheric radiation originates from
the sun and stars.
Earth’s atmosphere is very effective in shielding
cosmic radiation, but variations in the density of the
atmosphere can result in uneven distribution of
Additional Sources of Radiation
Our bodies contain naturally occurring radioactive
elements, such as potassium.
Some consumer products, such as luminous dial
watches and smoke detectors, contain small amounts of
Cosmic radiation can be accumulated through
one cross-country airplane trip.
Tobacco leaves absorb naturally occurring
radioactive materials from the soil and fertilizers
used to grow them.
Hospitalized individuals who undergo medical
procedures are exposed to sources of ionizing
Annual Dose from
Total US average dose equivalent = 360 mrem/year
Ionizing radiation is produced by the natural decay of
Beta, gamma, and x-rays are forms of ionizing
radiation that are often used in research.
Beta, gamma, x-rays
Ions are created,
which are more
Ions can form
compounds that might
interfere with cell
division and metabolism
or cause chemical
changes in tissue.
X-Rays & Gamma Rays
X-rays and gamma rays make up part of the
They can travel forever until they hit an object and
one of three reactions occurs:
-X-Rays & Gamma RaysX-rays and gamma rays can penetrate the body and
irradiate internal organs.
Exposure can result in external and internal doses.
Internal exposure can occur when rays are ingested,
inhaled, or absorbed through the skin.
Beta particles are excess electrons.
Particles can be low or high energy emitters.
Low energy emitters can be shielded by cardboard.
High energy emitters need a more dense shielding
material, such as Plexiglas.
-Beta ParticlesCan not penetrate the body to irradiate internal
Can penetrate dead outer-layer of skin and result in
damage to live skin cells.
Can cause damage to eye lenses.
Ingestion, inhalation, or absorption through the skin
might result in internal exposure.
Radiation Absorbed Dose
-RADRAD is a unit of measurement used to describe the
amount of energy transferred from a source of ionizing
radiation to any material, including human tissue.
It is the quantity of radiation received by a patient.
As a unit of exposure, 1 rad means that each gram of air at 0° C and
1 atmosphere has absorbed 100 ergs of energy.
As a unit of dose, 1 rad means that each gram of exposed tissue has
abosorbed 100 ergs of energy.
Radiation Equivalent Man
-REMDifferent types of ionizing radiation cause differing
degrees of biological effects even when the same level of
energy is transferred (same number of ergs).
Rem is used to express the quantity of radiation received
by radiation workers and populations.
The rate at which an individual is exposed also
influences the level of biological harm.
Dosimeter are used to measure a dose equivalent.
Biological Effects of radiation
Exposure above permissible levels may result in:
May be immediate or delayed
Birth defects due to irradiation to reproductive
cells before conception
Cancer or congenital malformation due to
radiation exposure to fetus in utero
-ThresholdThreshold effects might occur if an individual receives
a dose above the threshold level.
Acute Radiation Syndrome: large whole body dose in a short time
Effects occur at 100 rad
Radiation-induced cataract formation
Acute effects occur at 200 rad
Chronic effects occur at 800 rad
Severe skin injury occurs at 1,500 rad
Teratogenic effects occur at 20 rad
-Non-thresholdNon-threshold effects might occur from any amount
of exposure to radiation.
Chance of effect occurrence is proportional to the received dose.
Severity of effects are not necessarily related to exposure level.
Chance effects include:
Cancer - estimated to be 5 deaths per 10,000 persons, whom each
received 1,000 mrem
Summary of Biological
Effects of Radiation
• Deposit Energy in Body
• Cause DNA Damage
• Create Ionizations in Body
• Leading to Free Radicals
Which may lead to biological damage
Radiation Effects on Cells
Radiosensitivity Theory of Bergonie &
Stem cells are radiosensitive, mature cells are
Younger tissues are radiosensitive.
Tissues with high metabolic activity are
A high proliferation rate and a high growth rate
result in increased radiosensitivity.
Response to radiation depends
Stage of development at the time of
Whole Body Effects
Acute or Nonstochastic
• Occur when the radiation dose is large enough to
cause extensive biological damage to cells so that
large numbers of cells die off.
• Evident hours to a few months after exposure (Early)
• Skin burns
Late or Stochastic (Delayed)
• Exhibit themselves over years after acute exposure.
• Radiation induced cancers
• Genetic effects
When working with radioactive
material, remember to minimize your
exposure at all possible times.
Measure Your Radiation Dose
-DosimetersUse to measure the occupational dose equivalent from x-ray,
gamma, and high energy beta emitters. Dosimeters cannot
detect radiation from low energy beta emitters.
Whole body exposure
On the torso or area of
highest likely exposure
Exposure to a fetus
On either hand under the At the waist line
gloves with the name
facing the radiation source
X-rays & gamma rays:
X-rays & gamma rays:
1 – 1,000,000 mrem
30 – 1,000,000 mrem
High energy beta emitters: High energy beta emitters:
10 – 1,000,000 mrem
40 – 1,000,000 mrem
Dose Limits (MPD)
State and Federal regulations set maximum
permissible yearly radiation dose (MPD) limits for
Exposure up to dose limits is not expected to cause
adverse health effects.
ADULT MAXIMUM PERMISSIBLE DOSES
Whole Body – head, neck, torso, upper arms and legs 5,000 mrem
Lens of the eye
Extremities, skin, and internal organs
Declared pregnant woman
As Low As Reasonably
Always practice ALARA
AS LOW AS REASONABLY ACHIEVABLE
Why Practice ALARA?
Any type of ionizing radiation poses some risk. As
exposure increases, so does risk.
Research shows that some people’s DNA is more
resistant or susceptible to damage, and some people
have an increased risk of cancer after exposure to
Limit your exposure whenever possible.
Three Effective Strategies
-TimeMinimize the time and you will minimize the dose.
Pre-plan the experiment/procedure to minimize
Three Effective Strategies
-DistanceDoubling the distance from the source can reduce
your exposure intensity by 25%.
Use forceps, tongs, and trays to increase your
distance from the radiation source.
Move the item being worked on away from the
radiation area if possible.
Know the radiation intensity where you perform
most of your work, and move to lower dose areas
during work delays.
Three Effective Strategies
-ShieldingPosition shielding between yourself and the source of
radiation at all permissible times. Take advantage of
permanent shielding (i.e. equipment or existing
Select appropriate shielding material during the
planning stages of the experiment/procedure.
Plexiglas, plywood and lead are effective in shielding
radiation exposure. Use the proper shielding for the
type of radioactive material present.
Shielding X-Rays & Gamma Rays
Lead shielding will reduce the intensity of x-rays
and gamma rays being emitted from a source of
To reduce exposure by a certain desired percent,
lead shielding must be a certain thickness for each
type of emitter.
Lead shielding does not reduce exposure by 100%.
Lead lined plaster board
Lead glass viewing window
Personal Protective Equipment
Fig 3. Overshoes
Often worn routinely in the
Radiopharmacy for sterility reasons.
Not always otherwise worn routinely
contamination, but widely used for
this purpose following a spillage.
Radiation protection in X-ray
-Laboratory Rules1. Smoking, eating, and drinking are not permitted in
2. Food and food containers are not permitted in the
3. Radionuclide work areas shall be clearly designated
and should be isolated from the rest of the laboratory.
4. All work surfaces shall be covered with absorbent
paper which should be changed regularly to prevent
the buildup of contamination.
-Laboratory Rules5. Protective clothing shall be worn when working with
radioactive materials. This includes laboratory coats,
gloves, and safety glasses.
6. Dosimeters shall be worn when working with
relatively large quantities of radionuclides which
emit penetrating radiation.
-Laboratory Rules7. All containers of radioactive materials and items
suspected or known to be contaminated shall be
properly labeled with tape or tagged with the
radiation logo and the word “RADIOACTIVE”.
8. All contaminated waste items shall be placed in a
container specifically designed for radioactive
Mark all items used to manipulate or store
Label all contaminated items.
Remove all radiation labels
and warnings on containers
that no longer contain
radioactive material and are
Warning Label Requirements
MUST be clearly visible, durable, and MUST state:
“CAUTION: RADIOACTIVE MATERIAL”
Labels must provide sufficient information on the
container to minimize exposure and to make sure all
proper precautions have been taken.
Radioactive Waste Disposal
Radioactive waste includes anything that contains or
is contaminated with radioactive material.
Collect radioactive waste in proper containers.
Keep containers closed and secured unless you are
Report the proper information on the radioactive waste
tag when material is put in the waste container.
Keep a tag on the waste container at all times.