Lung cancer fatality risk and smoking habits

It is well known that there is a strong relationship between the smokers and the incidence and lung cancer fatality. A US lung cancer mortality study indicated the mortality rate increased with age and the number of fatalities from lung cancer among smokers increased very significantly as compared to non-smokers.

Mortality rate per 100,000 person-years

Age group                Non-smokers          Smokers

55 – 59 y                   5.3                              206

60 – 64 y                   11.6                           361

65 – 69 y                   21.5                           581

70 – 74 y                   34.9                           909

It is indicated that the incidence of lung cancer is more prevalent amongst the uranium miners who are exposed to radon (radioactive gaseous decay product from uranium and thorium series) and its decay products. The risk of incidence of lung cancer varies with the different smoking habits. Studies have indicated that there is enhancement (synergistic effect) in the lung cancer risk due to radon exposure and the smoking habits of the exposed persons.

This means risk of lung cancer resulting from unit radiation dose due to exposure to radon for people who are smokers is substantially higher than that of people who never smoked.

Exposure to radon is much more injurious to heath if you are a smoker. 

LNT approach is not justified for radiation protection

LNT controversy is appearing again and again in the scientific forums worldwide. In every forum it is said that there is no concrete evidence and justification to accept LNT approach for radiation protection purposes. Finally, it is said that in-spite of all the controversies, LNT is accepted in the radiation protection system since it is easier to manage the radiation doses, and for decision taking regarding w.r.t a practice or procedure.

Why this is forced acceptance? And what cost? Billions of dollars?

As a well-informed radiation protection professional, I am strongly of the opinion that:

1.     ICRP has recommended one-year dose limit of 50 mSv for occupational workers in the System of Dose Limitation. It is assumed that there are no clinically observable biological effects up to a dose of 100 mSv.

Accept 50 mSv as the threshold dose for stochastic effect.

2.     As a measure of good work practice, optimise the occupational exposures in a dose band of 10 to 50 mSv/y. Optimization to be carried out only up to a risk level keeping in view of the overall risk in perspective. 

[10 mSv is the annual dose accepted in radon at work places.]