Of Hares and Lions

Alarmed at sound of fallen fruit
A hare once ran away
The other beasts all followed suit
Moved by that hare’s dismay.

They hastened not to view the scene,
But lent a willing ear
To idle gossip, and were clean
Distraught with foolish fear.

The quotation is a translation from The Jataka, a body of Indian literature that relates to previous births of the Buddha, and dates to somewhere around the third or fourth century BC.  The story is perhaps the origin of the more modern story of Chicken Little, and tells the parable of a hare that lived at the base of a vilva tree.  While idly wondering what would become of him should the earth be destroyed, a vilva fruit made a sound when it fell on a palm leaf, causing the hare to conclude that the earth was collapsing.  He spread his worry to other hares, then to larger mammals, all of them fleeing in panic that the Earth was coming to an end. 

When radiation is discussed in the news, I often think of the story of the hare and vilva tree.  It seems that we are perpetually confronted with calls to overregulate radiation based on irrational fears of its effects on the human body.  Here I mentioned the persistent fears about radiation from cell phones and the passing of legislation in San Francisco last year requiring that retailers display radiation-level information when selling such devices, but there are many others that appear repeatedly in the news:  radiation from power lines, from computer screens, from cell-phone towers, and from any number of common household devices have at times been alleged to be responsible for causing cancer.  All of these allegations have uniformly been discredited in thousands of scientific publications over the last decades because they do not produce radiation at energies sufficient to break chemical bonds, a factor that is critical in the mechanism by which cancer is caused. 

Most recently, of course, there have been widespread reports of radiation being emitted from the damaged Fukushima Dai-ichi power plants.  There have been demands for governments to suspend the use of nuclear reactors in generating power and at least the German government appears to be acceding, with Chancellor Angela Merkel using absurd hyperbole in characterizing what is happening in Fukushima as a “catastrophe of apocalyptic dimensions.” 

There are legitimate concerns about radiation.  It does cause cancer in human beings.  Regulating our exposure to harmful radiation is an important and necessary role for governments.  But at the same time, rationality must surely prevail based on accurate scientific understanding of the mechanisms by which radiation causes cancer. 

There are a number of simple facts relevant to the debate. 

First, human beings have evolved in an environment in which we are continually exposed to radiation  — from cosmic rays, the Sun, and the ground all around us — and our bodies are adapted to exist with certain levels of radiation.  Indeed, the biological mechanisms by which we evolved as human beings are intimately related to that radiation exposure.  A wonderful graphic produced by Randall Munroe at xkcd illustrates different exposure levels and can be seen here.  One amusing fact shown in the chart is that consumption of a banana exposes a person to more radiation than living within fifty miles of a nuclear power plant for a year — and is dramatically less than the exposure from the natural potassium that exists in the human body. 

Second, there are only a limited number of viable options to produce energy at the levels demanded by modern society.  These are basically through the use of coal power generation and the use of nuclear power generation.  Other “clean” technologies that are frequently pointed to, such as wind and solar power generation, are wonderful technologies that are worth pursuing and which may one day be efficient enough to provide adequate levels of energy to replace coal and nuclear methods.  But that day is not here yet.  Those technologies are simply incapable of producing energy at the levels needed to support modern society and, in any event, have their own environmental concerns that need to be considered and addressed.  I commented, for example, on some environmental concerns associated with wind power generation here

Third, with the particular safety mechanisms that are in place, nuclear power generation is safer than coal generation, its only realistically viable alternative.  The xkcd chart cited above notes, for instance, that there is greater radiation exposure from living within 50 miles of a coal power plant for a year than living within the same distance from a nuclear power plant for a year.  The Clear Air Task Force, an organization that has been monitoring the health effects of energy sources since 1996, released a report last year finding that pollution from existing coal plants is expected to cause about 13,200 deaths per year, in addition to about 9700 hospitalizations and 20,000 heart attacks.  A copy of the report can be read here.  Nuclear power generation is also more environmentally responsible since it does not release climate-changing greenhouse gases in the way that coal power generation does.  When considering policy to reduce or eliminate the use of nuclear power — driven largely because the smaller number of deaths from nuclear power result from isolated high-profile events instead of the greater number of deaths that result from the persistent low-level effects of coal power generation — it is important to take these comparisons into account. 

I want to offer a final comment about radiation hormesis, which was recently raised most prominently by political commentator Ann Coulter in the context of the Fukushima event, although it has also been raised by other, more scientifically reliable, sources.  For example, Bob Park, a respected physicist who comments regularly on science and government policy, raised it in the context of a recent study that he interprets as showing that “Chernobyl survivors today suffer cancer at about the same rate as others their age [and that t]he same is true of Hiroshima survivors.”  His remarks can be found here.   Radiation hormesis is an effect in which low-level exposure to radiation produces beneficial effects and that has apparently been observed in laboratory settings.  It has not been convincingly confirmed in human beings and the exposure rates to produce the effect are, in any event, low.  My own view is that pointing to radiation hormesis as a positive argument for the use of nuclear power is counterproductive.  The effect is too speculative and there are too many other — stronger — arguments in its favor. 

The Jataka tells us that when the panicked masses led by the timid hare met a lion, it was he who restored their sensibility.  He brought them to their senses by looking coldly at the facts and determining that the earth was not breaking apart; it was only the misunderstood sound of a vilva fruit.  Let’s be lions, not hares.