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How do you estimate health risk from
chemicals and other substances?
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Last week's Risk Bites talked about health
risk as "the probability of something bad
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happening to your health."
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It's the kind of thing you might want to
know if you want to increase your
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chances of avoiding getting sick or
injured.
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But how do you go about putting a number on
health risk?
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especially as we are trying to predict the
future here, and there are many things that can
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influence how something might affect
your health.
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But over the years scientists have
developed a way of taking at least some
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of the guesswork out of assessing risk.
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Imagine, for instance, you're handling some
mystery substance - let's call it Unobtanium.
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How would you go about working
out what the risk is?
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The first step is to consider the
potential for this Unobtanium to cause
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harm if it got into your body -
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and what harm it might cause once it gets
there.
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"hazard" it presents.
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It gives an idea of how nasty the
stuff is if you come into contact
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But hazard alone doesn't say anything
about risk.
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It doesn't matter how hazardous the Unobtanium is, if you're not
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it cannot directly harm you.
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So the next thing we need to know is how much
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Unobtanium you're exposed to - including how it gets into your body
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and where it goes once it gets there.
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We are getting close to being able to
estimate risk at this point, but there's
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still something missing.
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We need to know how
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much Unobtanium causes what sort of effect.
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If we can measure this or estimate it, we
can connect hazard and exposure to the
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probability of harm occuring - risk, in
other words.
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This is the "dose-response" relationship, and
this is what transforms hazard
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and exposure into a measure of risk.
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Of course, we still need to know what to
do with this measure of risk, but that is
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a story for another day.
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For more insight into the science of
risk don't forget to subscribe to
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