Free Fukushima Book

Can be downloaded here.  Unfortunately, the chapter of radiation health effects includes this:

"Some researchers subscribe to the once discredited hormesis concept, a hypothesis that receiving low ionizing radiation in doses just above the natural background level may induce beneficial biological responses. The proponents of this hypothesis explain that a number of compensatory and reparatory mechanisms (e.g., stimulation of the immune response and DNA repair, and activation of apoptosis that eliminates damaged cells that would otherwise become cancerous) are stimulated in response to small doses of ionizing radiation."

It's still discredited....whether some researchers subscribe to the concept or not.