EPR-Public Communications
L-02
Communicating Basics of Radiation
Simple
Challenge
• Communicating with the public about
radiation is challenging;
• Communicate in plain language;
• You will communicate better with people if
you can think as they are thinking.
Sources
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Radiation is naturally present in the
environment. This is called natural
background radiation;
People are exposed to natural radiation
from outer space, the air, food and drink;
People may also be exposed to artificial
radiation from medical treatment,
consumer products and occupational
exposure;
Often, medical exposures from diagnosis
and in treatment account for the largest
dose from artificial sources.
Cosmic radiation and dose rates of exposure
Types of radiation
Alpha radiation (α)
Beta radiation (β)
Gamma radiation (γ)
Radiation that has a
short range in air and
can be stopped by paper
or skin. This radiation
can be hazardous if it
enters the body by
inhalation or ingestion
because large exposures
can result in nearby
tissues.
Radiation that can
penetrate further into
materials or tissue, but
can be stopped by
plastic, glass or metal.
This radiation does not
normally penetrate
beyond the top layer of
skin but large exposures
can cause skin burns
and is also hazardous if
it enters the body.
Very penetrating
radiation for which only
dense material such as
steel or lead can provide
an effective shield. It can
deliver significant doses
to internal organs without
needing to be taken into
the body.
Types of radiation
Exposure pathways
Inadvertent ingestion
Common exposure pathways for a
small radioactive source
Quantities and units
The becquerel (Bq) is a unit used to measure radiation.
When ionising radiation interacts with biological tissue, it deposits energy there. The amount of energy deposited
per unit mass of tissue is called the absorbed dose: the unit of this dose is called the gray (Gy).
Measuring
radiation
Since equal exposures to different types of radiation expressed as Gy do not necessarily produce equal biological
effects, these doses are weighted to give units of dose as the effective dose, or sievert (Sv). The sievert
determines the probability that an ill-health effect will ensue. Regardless of the type of radiation, 1 sievert of
radiation produces the same probability of biological effect (cancer or hereditary effects). Sievert is calculated and
not measured.
The amount of radiation – the “dose” – received by people is measured in sieverts (Sv). This takes into account
the type of radiation and how a person is exposed to that radiation.
Dose of radiation
Example: A typical dose received due to the natural sources of radiation is 3 milliSieverts in a year (written 3 mSv
or 0.003 Sv).
The sievert belongs to the same family as the litre and kilogram. To explain the prefix “milli” compare with
commonly used units such as litre (l) and millilitre (ml).
Dose rate is the rate at which dose is received. It is often used to calculate the intensity of a radiation source.
Dose rate
Example: The dose rate at one metre from a source is 50 microsieverts per hour (written 50 µSv/h). If a person
stood in this radiation field for 2 hours, he/she would receive a total dose of 100 µSv.
Here, a µSv is a million times smaller than a Sv and a thousand times smaller than a mSv.
Effects of radiation
• Deterministic: short term, occurring early
after exposure;
• Stochastic: long term, occurring years later.
Recognizing a radiation source
Trefoil radiation warning symbol
New standard ionizing radiation warning
supplementary symbol
Radiation protection
• Time
• Distance
• Shielding
Am I safe?
In addition to dose and dose rate quantities
the following questions must be answered:
• What was measured or reported?
• How was the person exposed (exposure
scenario)?
• Who was exposed?
Potential health effects
• Death;
• Severe health effects (severe deterministic
effects):
• Severe burns;
• Other non-fatal effects.
• Health effects to foetus;
• Cancer risk.
Health effects from being near an
unshielded radioactive source
HEALTH EFFECTS FROM BEING NEAR AN UNSHIELDED
RADIOACTIVE SOURCE BASED ON EXTERNAL DOSE TO THE WHOLE BODY
HEALTH EFFECTS
Death
Possible*
EXTERNAL DOSE
TO THE WHOLE
BODY
Severe
health
effects
possible*
1000 mSv
Health effects*
possible in the fetus
Very small
increase in
cancer risk
if any**
100 mSv
Average annual
dose to the public
10 mSv
2 mSv
* Medical follow-up by
an expert is warranted.
** No increase in cancer incidence has been
detected below about 100 mSv
Health effects from carrying an
unshielded radioactive source
HEALTH EFFECTS FROM CARRYING AN UNSHIELDED
RADIOACTIVE SOURCE - BASED ON DOSE RATE
HEALTH EFFECTS
DOSE RATE OF
SOURCE at 1 m
Death and other severe health
effects* possible from carrying
an unshielded source for:
Severe burns* possible from
carrying an unshielded
source for:
minutes
minutes
hours
Health effects*
possible in the fetus
from woman carrying
an unshielded source
100 mSv/h
10 mSv/h
hours
1.0 mSv/h
0.1 mSv/h
* Medical follow-up by
an expert is warranted.
Health effects from being near an
unshielded radioactive source
HEALTH EFFECTS FROM BEING NEAR AN UNSHIELDED
RADIOACTIVE SOURCE - BASED ON DOSE RATE
HEALTH EFFECTS
DOSE RATE
Death and severe
health effects* possible
from exposure for:
minutes
5000 mSv/h
1000 mSv/h
hours
100 mSv/h
days
10 mSv/h
weeks**
Health effects*
possible in the
fetus from
exposure for days
* Medical follow-up by an expert is warranted.
** Severe health effects have not been seen in
past emergencies from being near a source with
a dose rate < about 10 mSv/h @ 1 m.
1.0 mSv/h
0.1 mSv/h
Let’s practice
• Some questions…