Item: A study finds that between 1970 and 2009, melanoma skin cancer cases increased eight times in women aged 18-39, and four times in men, apparently from increasing use of tanning beds.
Item: Many of the evacuees around Fukushima are being allowed to move back into their homes because the low level of radioactive contamination poses no health threat.
What do these issues have in common? Two things; radiation, which in all its forms scares a lot of people, and choice, one of the most influential psychological characteristics that make radiation, or any risk, more scary or less. Together, these items provide a clarion lesson about how the perception of risk is subjective and emotional, and how that can be risky all by itself.
Consider the people who choose... PAY... to bathe themselves in carcinogenic radiation. Why? For a tan... for that 'nice healthy glow' society has come to associate with vigor and attractiveness. These people dismiss the risk by saying things like "It won't happen to me," which is known as Optimism Bias, or "I'm only doing it a little," fooling themselves that they are controlling the risk and therefore, somehow, they don't have to worry about the risk they are still taking. The more we feel we control a risk, the less afraid of it we are, and vice versa.
These are common psychological games we play with ourselves in order to do things we know are risky, because they offer some benefit and we want to do them. We play down the risk so we can enjoy the benefit. Driving after drinking or while using a cell phone to text or talk, weighing too much but overeating and not exercising, riding a bike or motorcycle without a helmet... there are tons of examples.
But a really big factor in how any risk feels is choice. A risk you choose feels less risky than if the very same risk is imposed on you by someone else. The cancer risk from radiation would feel completely different to those willing tanning bed customers if they were tied down and told that they were about to be tanned with radiation released from a nuclear power plant accident. (Ever been driving and talking on your cell phone, and you notice the driver in the next lane is talking on HER phone and weaving in and out of her lane and speeding up and slowing down, putting you at risk... and THAT makes you upset, even though you're doing the same thing? Like I said, there are lots of examples of how choice makes the same risk feel more, or less, risky.)
Now consider 67 year-old Akiko Tsuboi, who fled from her home in Tamura Japan near the Fukushima nuclear complex during the crisis last year, and has lived in emergency shelter housing since. She just returned to the house in which she raised her three kids, though low levels of radiation remain in the soil, and set out a vase of flowers to brighten the place up and said "I'm home!" Schools in Tamura will reopen soon.
That hardly seems to match the alarmist way some people talk about nuclear radiation, particularly opponents of nuclear power, who fear, often dramatically, that exposure to any dose is too high a risk to accept. In fact, while some radiation biologists believe that any dose does raise the risk of cancer, some studies (PDF) of the survivors of the atomic bombings of Hiroshima and Nagasaki found that below a threshold, no biological effects could be detected in people who were within two miles of the detonations of atomic weapons. (That threshold is 100 milliseiverts. The levels in the soil in much of the Fukushima evacuation zone are well below that.)
Akiko is willing to accept that evidence, so she can enjoy the benefit of returning to her home, voluntarily. People who fear nuclear power are not, and one of those reasons for their fear is that radiation from a nuclear power plant accident is imposed on the victim. Same risk... very different feelings. Could there be a more clarion example of how risk is not some simple absolute truth, some set of facts and probabilities with which we can all agree? Risk is a feeling, a subjective interpretation of the facts and numbers through a set of subconscious instinctive and emotional filters that can make the same facts seem more scary, or less.
The real lesson is that this way of perceiving risk can be risky all by itself. As valid as our feelings feel, they sometimes cause us to be too afraid, or not afraid enough, and as this example teaches, that can raise new risks. It's raising the risk for people who aren't afraid enough of radiation and pay to expose themselves to a known carcinogen, and it's raising the risk for you and me., as excessive fear of the biological threat of radiation has lead to energy policy that favors fossil fuels, exposing us all to local particulate air pollution and global climate change.
Oops! These are lessons worth learning, in the name of keeping ourselves safer and healthier.