Risk calculation for your granite countertop
Lots of discussion about granite countertops, Radon, and radiation. Homeowners are wondering who to believe or what to do if they have a granite countertop.
The bottom line for most people on this issue is how dangerous or how safe is my granite countertop. This has been a difficult question to answer, many variables need to be taken into consideration, dose rates converted into existing risk factor units, difficult to do quickly.
But, today we found a handy Risk Calculator on a nuclear site. You can insert the radioactive reading of your granite top in what ever units the meter reads in, set the number of hours you spend near or in the kitchen, the occupancy length, and chose to use the public or worker Risk Factor. For now, lets consider Gamma only, since we are concentrating on that risk because it is easy to measure and is indicitive of the Radon emission.
Using 41 uR/hr (Class A max), 2 hours per day in or near the kitchen, 365 days per year, a lifetime occupancy, and the public Risk Factor, the extra cancer rate is 1 in 893 people exposed. Lots of granites in this range.
Using 20 uR/hr, same factors, 1 extra cancer in 1832 people exposed.
Using a hot slab, 100 average reading across the slab, 1 extra cancer in 366 people exposed.
Using a very hot slab, 150 uR/hr average reading across the slab, 1 extra cancer in 244.
So low level stones like Uba Tuba, Black Pearl, Absolute Black, the extra cancer cases will be between 1 in 1832 and 1 in 3660 people.
If we add the Alpha and Beta to the Gamma, things get pretty scary.
Verde Peacock, 500 uRhr, 1 extra cancer in 73 people exposed.
Bordeaux, 1.7 mR/hr, 1 extra cancer in 21 people exposed.
Niagra gold, 5.1 mR/hr, 1 extra cancer in 7 people exposed.
Four Seasons, 13.1 mR/hr, 1 extra cancer in 2.8 people exposed.
Savanah, 17 mR/hr, 1 extra cancer in 2 people exposed.
Keep in mind that spending more time in the kitchen will change these rates upward.
Even the low level slabs, at 1 in 3,660 , will affect a large number of people. Assume that 30 million people have low level granite countertops in their homes, 8,196 extra cancer cases will result assuming 2 hours per day use of the kitchen, using Gamma exposure only, no Radon, Alpha, or Beta.
Eight thousand, one hundred ninety six extra cancers cases…..
If you want to know the danger to children, change the Risk Factor in the public box to .08 to reflect childrens extra risk from radiation.
Using 41 uR/hr Gamma only (class A limit), 2 hours per day, and five years exposure, expect 1 extra cancer in 7,817 children exposed.
For infants, use .09 for the Risk Factor in the Public box to reflect an infants extra risk from radiation. .
For an infant, using our Class A stone of 41 uR/hr Gamma only, 2 hours per day and 5 years exposure figure 1 extra cancer in 6,949 infants exposed.
For an Infant, using Bordeaux, 1.7 mR/hr of ALpha, Beta, Gamma, 2 hours per day and 5 years exposure, figure 1 extra cancer in 167 infants exposed.
2 Responses to 'Risk calculation for your granite countertop'
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on May 30th, 2009 at 1:03 am
[...] The relatively ’solid’ patterns with less movement (Uba Tuba, Black Pearl, Absolute Black) pose a much smaller risk than the exotic granites. The ones with a lot of “movement” with brown and yellow flecks are the ones most likely to be suspect (Niagra Gold, Savannah, Verde Peacock, Four Seasons Crema Bourdeaux, Yellow Star, Tropic Brown, Baltic Brown). It depends, to a large extent, upon where they are mined. (Granite countertop radiation risk calculator) [...]
on May 30th, 2009 at 8:18 am
Thanks for the link back jugabandi. I posted a reply warning your readers about the toxic heavy metals in granite. I would certainly test a granite tile before using it as a baking surface.
Movement along doesn’t always predict radiation content. Stones like Carocia Gold, Baltic Brown, and yellow can be elevated.