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Re: radium question

July 11, 1999
Davis, CA

According to the Robert E. Rowland book (RADIUM IN HUMANS, Argonne National
Laboratory, 1994), the lowest skeletal dose for which fatal bone cancer was
observed among the 2,403 persons included in the study was 11.6 Gy (232 Sv
for this alpha irradiation, or 23,200 rem) from a systemic intake of 78.8
microcuries of Ra-226 and 17.2 microcuries of Ra-228 (Case # 05-917). As
Rowland explains, the actual intake for persons developing head carcinomas
was probably no lower. 

If a person were to drink 2 L per day of water containing the current
maximum permissible limit of 5 pCi/L it would take 131,417 years to achieve
an intake equal to that of the person with the lowest dose for which
effects have been observed (assuming 20% intake by ingestion)! For water at
12.5 pCi/L it would take 52,567 years!

Obviously, the current drinking water standards for radium are not based on
any actual biological effects. Water with 12.5 pCi/L poses no known threat
even if drunk every day.


		Prof. Otto G. Raabe, Ph.D., CHP
              Institute of Toxicology & Environmental Health (ITEH)
		   (Street address: Building 3792, Old Davis Road)
		University of California, Davis, CA 95616
		Phone: 530-752-7754  FAX: 530-758-6140
		E-mail ograabe@ucdavis.edu
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