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Kevin,
Did you take the time to read what you linked to? That thing relied on info that is nearly fourteen years old ! Here is the first sentence in the Editor’s notes at the start of the article!
“It has been reproduced from its publication in The Journal of Nuclear Medicine, Vol. 35, No. 2; Feb 1994 and material submitted by the author”
Still some good info can be pulled from it. It proves much of what I have been saying all along. Smokers are at risk the most, followed by those in high Radon level homes and all homes with high Radon levels shouldn’t install granite or other radioactive materials inside the home.
“Evidence for a health effect from radon exposure is based upon data gathered from epidemiologic studies of miners, and animal studies. Extensive radiobiologic data predict a linear dose response curve in the low dose region due to poor biological repair mechanisms for the high density of ionizing events that alpha particles create. If this is the mechanism that underlies lung cancer induction, there is reason to believe that there will be some degree of increased lung cancer risk even from low level environmental radon exposures.”
” Based on these estimates, radon in equilibrium with its daughters delivers 2 times more dose than previously accepted as the total dose received from all sources of natural background exposure (approx. 100 mrem/year on the average in the United States). Thus, it is not surprising that adoption of the effective dose notion by many radiation protection groups (including the NCRP and the EPA in the United States), has led to increased concern regarding the potential health effects of radon. “
Look down to Table 1 in the article, notice the huge Dose Equivalent of 2400 mrem compared to the other sources.
Note the increased danger to homeowners versus having granite in a work place :
“Thus, a 12 hour a day exposure in the home at one WL, corresponds to approx. 26 working level months per year i.e. 2.1 X the occupational exposure, assuming equal radon levels at home and in the work place. “
So the increase hours that a homeowner spends gets them 2.1 times the exposure assuming equal radon levels.
“The amount of time spent in the mine or in the home determines the number of WLM associated with a particular exposure level, but because most people spend more time at home than at work, the WLM could be higher than from a comparable mine radon daughter concentration.”
Again they say that you are in more danger at home than at work in a mine! And Kevin still claims that adding to the level won’t hurt?
“Dose calculations depend on the airborne radiation levels and concentration of radon and its progeny and on the modeling assumptions noted above (20). The radiation levels can now be measured with reasonable accuracy and precision. Present calculations for an average indoor and outdoor exposure (0.75 pCi/liter) to a cell 22 um deep, in a 4th generation airway, range from 140-340 mrad/year, with the highest doses to 10 year old children. (Note: a continuous exposure to radon at a concentration of 1 pCi/liter would result in an annual exposure to radon progeny of 0.25 WLM/year, which corresponds to 188 mrad/year, or 3750 mrem/year for an adult, assuming a quality factor of 20 for alpha particles.) (1).”
The above quote is especially revealing since it mentions that 10 year old children receive the highest doses. The 3750 mrem a year for an adult. Compare that to wha this site says is the allowable exposure to a pregnant woman, 500 mrem for the entire pregnancy. Note that a minor is allowed only 10% of the yearly allowed dose because of the increased susceptability of children and adolescents to radiation. The general public is allowed only 100 mrem dosage.
They also mentioned that the average Radon level was 0.7 pCi/gram but it can be twice that in some cases. Let’s do the math,
453.59 grams per pound, granite averages say 16 pounds per square foot, average top is 75 square feet = 544,308 or a half million grams of granite times the average Radon level of .07 = 381,015 pCi available Radon in an average granite countertop. That is in pico Curies a very small number, but lots of numbers.
Compare thisdose equivalent from drinking 2 liters of water a day containing just 5 pCi of Radon. 5 compared to 381,015…
Note also what happens with long term dosage, the dosage absorbed at year 30 is 270 times that of year one.
Now we have to convert pCi into Bq, which is 1 pCi = 3.7 x 10 to the negative second power, or .37 Bq. take our Radon 381,015 pCi divided by the .37 = 1,029,770 Bq of available Radon in that average granite countertop. 200 Bq is the accepted safe level, or at least the level we are willing to lose people to increased cancer rates. What is unknown is the rate of decay that makes this Radon released into a home.
further down, in table 5, it lists building materials releasing 0.01 – 1 Bq (0.3 – 30 pCi) of Radon, and in Table 6 it lists concrete with an average level about that of granite while also saying that concrete is the major emitter of Radon. In their building material lists, granite is not represented but we can estimate using concretes levels.
At the end of the page, they repeatablly blame granite as being responsible for the worst Radon levels in homes.
On page two, a Swedish study reported a 15% of the cancer cases studied were due to Radon.
It also says this
“Assuming a population of 240,000,000 in the USA, between 4500 and 23,000 lung cancer deaths could be attributed to radon exposure annually (54). “
If only ten percent of these cases can be attributed to granite or building material radon…..
And on page two, there is a risk chart that shows risks per level or Radon.
That was some old data, but it still proved the point that Radon is dangerous, granite emits it and the granite industry is remiss in not coming forward on testing individual slabs.
