Re: background radiation and cancer

["Otto G. Raabe" <ograabe@ucdavis.edu>]

September 18, 1997
Davis, CA

How do people estimate the cancers they believe are "caused" by background
radiation? This is an easy calculation. The average person in the U.S.
receives about 1 mrem/day effective dose equivalent from background sources
including inhaled radon decay products (BEIR-V). That is 0.36 rem per year.
According to the ICRP (ICRP-60) the cancer risk to the general public from
exposure to ionizing radiation is 5 x 10^(-2) per Sievert for 5 x 10^(-4)
per rem. The annual cancer risk to U.S. residents is therefore: 0.36
rem/year x 260,000,000 people x 0.0005 = 46,800 cancers per year. This is
3.7% of new cancer cases per year and 8.7% of cancer deaths per year. 

Of course, this calculation is wrong! The linear model that the ICRP uses
is unproved speculation and misleading. Cancer rates in the U.S. tend to be
inversely related to the levels of background radiation exposure. For
example, people living in Colorado are possibly the most highly irradiated
Americans receiving an average of about 3 mrem per day or 1 rem per year
effective dose equivalent from background sources. Yet Colorado enhoys one
of the lowest cancer occurrence rates of all the States. Only New Mexico,
Hawaii, and Utah have lower rates. (Hawaii seems to be an exception since
it has low cancer rates and also the lowest background radiation levels). 

Otto
		*****************************************************
		Prof. Otto G. Raabe, Ph.D., CHP
                [President, Health Physics Society, 1997-1998]
		Institute of Toxicology & Environmental Health (ITEH)
		     (Street address: Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 916-752-7754     FAX: 916-758-6140
		E-Mail: ograabe@ucdavis.edu
		******************************************************