Demands for zero levels of risk are frequently made by environmental groups. A zero level of risk is impossible to achieve in any sphere and such demands are therefore unreasonable. These demands can also force the concentration of all available safety resources into areas targeted by environmental groups in an attempt to eliminate small residual risks, at the expense of ignoring larger risks in non-targeted areas.
Picture a typical scene. An environmental activist and a technical expert are debating the safety of a commercial product. The expert is convinced that the product is safe and quotes the tests that have been performed to prove this point. The environmentalist is not convinced, citing other evidence to show the product is doubtful. Then the environmentalist asks the expert: "Can you guarantee that there is no risk attached to this product?" The expert replies: "There is no evidence that this product poses a risk and there is much evidence that it is safe. However, as a scientist, I cannot give an absolute guarantee that there is no risk."
In a public debate the expert has now lost the argument because the public wants a guarantee. The activist guarantees risk, the expert cannot guarantee safety.
Science can make pronouncements in its own sphere probably with greater confidence than any other discipline can make in its own sphere. But it is also the nature of science that there is no certainty, only degrees of probability. Scientific knowledge must remain
able in the light of new evidence. For example, an astronomer cannot guarantee that the sun will rise tomorrow. The sun has risen every dawn since the formation of the earth, and we know why from the laws of celestial mechanics. The probability that the sun will rise tomorrow is enormously large and from a common-sense point of view the matter is certain. However, the probability that the sun will fail to rise is not zero. It is computable, and from a scientific viewpoint sunrise cannot be guaranteed.
Let me return to the expert and the activist. Let us assume that the expert is unbiased, has carried out extensive tests and has reviewed all the literature on the subject. Let us say that as a result the expert can have a confidence level of 96 per cent that the product is safe. This leaves a doubt of 4 per cent, mainly because product safety has not been tested under an infinite number of conditions. The activist's case that the product is dangerous has only a 4 per cent chance of being correct.
Of course, I deliberately set up the preceding scene to make a particular point. However, my aim is not to canonise experts and to damn environmental activists. In some cases the expert is no more than a `hired-gun' recruited to put an acceptable face on self-interest, and in some cases the activists are experts who take every effort to base conclusions on objective data. Many other cases fall somewhere in between. But unfortunately the scene I painted, where the activist seems largely motivated by an evangelical faith, is not uncommon.
Life is full of risk even if you stay in bed. Your muscles will waste from disuse and a plane may drop from the sky and kill you. Things get really hairy when you arise from bed. There is a real danger you will trip and fall down the stairs. Next you must avoid electrocuting yourself as you cook breakfast. Then to the deadliest danger of all - driving to work. About 500 people are killed on the roads every year and thousands are injured. And so it goes on through the day, everyday. Every living moment is accompanied by risk.
The only way to live therefore is to decide what activities are worth pursuing, try to understand and measure the risk involved, devise ways to avoid/minimise the risk, and then proceed with caution. Sometimes our analysis will indicate that the risk so far outweighs the benefit that we should avoid the activity altogether, e.g. sun-bathing.
Demands are often made in the environmental area that we must not proceed in certain directions until we are certain that it is safe to do so.
This sounds sensible, but we must remember that little or no human progress would ever have been made if this advice had always been followed. The only sensible way to do things is to proceed with caution as previously described. For example, there is sufficient evidence that the build up of greenhouse gases may be causing the world to heat up. It would therefore be irresponsible to continue to allow these gases to increase.
Also, in the 1950s, a strong argument was made that man should not land on the moon lest he carry back an alien organism that might devastate life on earth. It was decided to go ahead anyway, although returning astronauts from the first missions were quarantined for a period on earth to check them out.
And finally, an example of the selective targeting of one risk while ignoring another. We all continually breathe in the natural radioactive gas radon which emanates from rocks in the earth. It is estimated that radon is responsible for 10 per cent of lung cancers, but public consciousness of the problem is very low. In some parts of Ireland indoor radon builds up to unacceptable levels in domestic houses, e.g. in a 10km square in the southeast of Cork city and surrounds, including part of the harbour. A few years ago I described this in an article and pointed out that it is relatively easy and inexpensive to reduce high radon levels. I was telephoned by an environmental activist and asked to identify the industries in Cork harbour that emit radon. I explained that radon was not coming from industry but from the earth. The activist immediately dropped interest in radon since it is not an industrial hazard.
William Reville is a senior lecturer in Biochemistry at UCC.