A Century of Radiation
The
explosive and sometimes reckless exploitation of Rontgen and Becquerel's
discoveries produced medical technologies that dramatically added to the
diagnostic and therapeutic tools available to physicians. But the consequences
for some of the pioneers were dreadful and it took 
decades
to understand and control them. Later, the exploitation of discoveries of
nuclear physics led, from the 1940s, to nuclear weapons and nuclear power
with overwhelming potential for harm. The genetic damage seen in earlier
animal experiments was the first concern but, as the long-term results of
the A-bombs dropped on Japan emerged, it became clear in the 1960s and 70s
that cancer was the most serious health effect. Quite how radiation damages
cells and causes the effects it does has been studied since the earliest
days and, since the leap forward that came with understanding the significance
of DNA, there has been remarkable progress. However, it is still not fully
understood and some key elements remain controversial – notably the
likelihood of effects at very low doses. Our knowledge is still largely
based on the Japanese experience but there are new data emerging as epidemiological
studies become better coordinated and are combined.
While our understanding of how radiation damages has evolved so has our knowledge of its sources: we now know that the largest one for most people is the natural world around us. It is an understanding that has been won through undramatic work developing measurement techniques and defining key concepts and quantities. This has also given us an understanding of the effects of radioactivity taken into our bodies and this, in turn, has allowed us to compare quite different sources of radiation: medical procedures, natural radiation, nuclear power.
Measuring and understanding is one thing; control is another. The first successes were the rather crude recommendations for the control of the exposures of early physicians. While they reduced the horrendous acute injuries, they could not recognise the more insidious possibilities of cancer. Their central idea was that there was a threshold level of dose below which effects were insignificant - and this persisted until well after the Second World War. The dominant notion that followed – all radiation carries some risk of cancer, increasing as the dose increases - posed new challenges for protection. If all radiation can cause harm, how are we to balance that with the benefits some of it brings? This became a key question from the early 1970s and remained one until the end of the century.
