[exDemMom]

The effects of exposure (to anything: radiation, toxins, visible light, sound, etc.) all operate according to a sigmoidal curve. At the bottom left side of the curve, small exposures have unnoticeable effects. As the exposures increase, the effects increase very slowly. But at some point, there is an inflection at which the effects and the exposure have a linear relationship. This continues for some time until the system becomes saturated. At this point, another inflection occurs and increasing the exposure further has hardly any effect. The inflection point is where the curve changes direction.

Just about all biological processes follow this curve.

[exDemMom]

I forgot to mention: this is the basis on which scientists analyze their work. In the research world, LNT is not considered. The concept of LNT is mostly used by policy makers.

[AZJeep]

It is actually theorized, that small amount of radiation is GOOD for you!

Places with high levels of natural radiation are generally healthier than places with very low radiation.

Extreme example, Ramsar, Iran, a city with the highest natural radiation in the whole world (a level which should call for immediate evacuation!) is a well known spa (on the Iranian level), where people travel to get better!