People are constantly exposed to radiation from natural sources. But government regulators typically act as if every bit of exposure to man-made sources of radiation such as from nuclear power plants is potentially hazardous.
So the question arises as to how much radiation exposure is harmless and at what level does it become harmful?
A standard chest x-ray, by comparison, gives about 10 millirems to the chest which is equivalent to 1 or 2 to the whole body.
At various spots on the earth’s surface, human exposure to cosmic radiation can range from roughly 100 to 200 millirems a year and natural variations in radiation exposure are many times the amounts that are being disputed by regulatory agencies.
Source: Gina Kolata, For Radiation, How Much Is Too Much?. New York Times, November 27, 2001.
For text http://www.nytimes.com/2001/11/27/science/physical/27RADA.html?searchpv=past 7days
For more on Human Health Risks http://www.ncpa.org/iss/env
FMF Policy Bulletin\4 December 2001




