2015 Nobel Prize in chemistry for work on DNA repair

Three scientists from Sweden, US and Turkey won the most prestigious Noble Prize for their works on DNA repair mechanism. The three scientists are: Swedish citizen, Prof. Tomas Lindahl (UK); US citizen Prof. Paul Modrich (USA) and US and Turkish citizen, Prof. Aziz Sancar (USA). Prize money of 8 million Swedish Krona to be shared equally between them.

Our body consists of cells of different types. Deoxyribonucleic acid (DNA), stored in the nucleus of every cell, contains genetic code written in chemicals.  DNA replicates itself during cell division. During this process something can go wrong and there can be damage to the DNA molecule. The DNA damage (called mutation) can also take place due to many other reasons, such as exposure to some chemicals, radiation and many other environmental pollutants, both physical and chemical.  The repair mechanism is able to repair this continuous damage of the DNA due to variety of reasons. Prof. Lindahl studied the degeneration or DNA decay over time and how the DNA repair takes place at molecular level.  

Enzymes, viz., specialized protein molecules, act as media in DNA repair through chemical reactions taking place at molecular level. The work carried out by these scientists helped in understanding the working of these repair mechanisms; and will help in better understanding of the chemistry behind ageing process and other diseases, including cancer.

One of the three scientists, Prof. Aziz Sancar worked on repair mechanism of the DNA damage caused by the exposure to visible light and UV radiation. He worked on the repair mechanism which made DNA in bacteria exposed to lethal doses of UV radiation to recover under blue light. However, in mammalian cells, a different repair mechanism, called nucleotide excision repair works. However, there is a possibility of a tiny mismatch during the repair of damaged DNA strands. There exists in the cells, enzymes which repair these mismatches in the DNA strands. Prof. Paul Modrich studied the mechanisms correcting such mismatches.   

My comment: The scientists have been doing great work for years on this all important and complex subject of repair of damaged DNA. The damage has been taking place spontaneously and also due to exposure to other agents, including natural background radiation. I failed to understand how some one can say that the cancer cases seen in the population is due to exposure to low level ionizing radiation from nuclear facilities?  It is time that researchers experimentally prove, beyond doubt, that there is no linear no-threshold (LNT) relationship between exposure to radiation and the cancer.