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[Person 1:] No, I don't think it's ever safe
to be around radiation.
Like even a little bit can make you sick,
like throwing up and stuff.
[Person 2:] Any kind of radiation is dangerous.
I mean, that's why they took those machines
out of the airports - the ones
that can scan through your clothes.
It was too much radiation for people to be around.
It could make someone sick.
[Person 3:] I think you'd have to have something protecting you
like what's that thing at the doctor's,
the lead thing they put in front of you for an x-ray,
but if you didn't have that,
I think that it's definitely not safe.
[Vivi:] Armin, these responses echo sentiments we've heard time
and time again.
People think even a small amount of radiation will harm them.
Is that true?
[Armin:] Well, first we should say that there are a wide range
of health effects from radiation,
from no effect to death.
The health effect depends on the radiation dose,
the type of radiation, the length of time we are exposed,
your age, and individual sensitivity.
Some health effects are acute - they happen right away,
if we are exposed to a very high level of radiation
over a short period of time.
That's where we might see nausea, diarrhea, skin damage,
possibly seizures and coma.
Other radiation effects are much longer term.
For example, people who receive low to moderate doses
of radiation could have a greater risk
of developing cancer later in life.
[Vivi:] Is there any safe level?
Why do we have such a hard time saying a low level exposure is
"safe"?
[Armin:] Well, we should add
that it is not only radiation protection professionals
who have trouble using the word safe.
Health and safety professionals in any field are hesitant
to say an activity or exposure is "safe" because first of all,
safety is a matter of perception.
It is a subjective characterization
and involves personal judgment.
A good example is the sport of skydiving.
Some people skydive for fun, and statistics show
that accidents are very rare.
But some people like me are scared of even trying.
Secondly, safe implies zero risk.
And zero risk can seldom be guaranteed for anything.
It comes back to the ability to be certain
that a particular exposure won't cause some health effect many
years later.
[Vivi:] Like cancer can show up years after an exposure?
[Armin:] Let's look at cancer.
Because many factors can contribute
to a person's cancer risk, it is very difficult,
if not impossible, to identify the additional incremental risk
presented by low doses of radiation
for a given person or group of people.
I have a diagram that will help demonstrate this.
The baseline cancer risk for a person in the US is about 40%.
That means the average person in the US has a 40% chance
of developing some type of cancer
at some point in his life.
Of course, this is just an average, and it could be higher
or lower depending on the person's gender, lifestyle,
genetic makeup, and environmental factors.
Now, let's say someone receives a radiation dose
that we estimate increases the cancer risk on average by 1%.
Of course there is variability in that estimate as well.
So even though the estimated increased risk is 1%,
factoring in the uncertainty could make that higher than 1%
or lower than 1% - even zero.
Often, for radiation doses that we may encounter, we are talking
about estimated additional risks that are even lower than 1%-
for example one tenth of one percent.
So, while the actual increased cancer risk
at these low doses may be very low or even zero,
there is uncertainty in our estimation,
and radiation professionals are hesitant to be definite
about this and use the word "safe"
when these uncertainties exist.
[Vivi:] That's really important context to have.
When we're talking about an incremental increase in a risk
over a long period of time, giving people context
and using comparisons can be helpful.
It's also important for us to acknowledge the uncertainty.
Along with this we need to show empathy
in acknowledging people's fears.
Hearing you've been exposed to radiation outside
of expected situations can be scary,
no matter what the dose or the health effect.
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