For those into natural stone sales this can be of use...

http://www.marble-institute.com/industryresources/trifoldradonbrochure.pdf

A few finds,

"Radiation measurements on granite surfaces can show levels similar to those from low-grade uranium mine tailings."

Thoruim aveages 17 ppm,

"Radium-226 is one of the decay products of uranium-238, a uranium isotope widespread in most rocks and soils. When this radium decays it produces radon-222, an inert gas with a half-life of almost 4 days. Radium-224 is a decay product of thorium, and it decays to radon-220, also known as thoron, with a 54-second half-life. Because radon is so short-lived, and alpha-decays to a number of daughter products which are solid and very short-lived, there is a high probability of its decay when breathed in, or when radon daughter products in dust are breathed in. This is a problem because alpha particles in the lung are hazardous to human health. "

This link states that  50 and even 500 ppm uranium in granite.  

Looks like worst case would be 12 to 125 times what the MIA reports.    Imagine that.....

"The highest average values of ²²⁶Ra and ²³²Th concentrations (24.00 and 31.28 Bq kg^–1, respectively) were observed at Abu Herigle region, whereas the highest average value of ⁴⁰K concentration, 589.95 Bq kg^–1, was detected in Umm Hibal. "

"Fractures and pores allow radon to diffuse more quickly"

Seems that there is quite a difference between old and more recent granite.    Here is a link that gives these values

  Older granite,  Radon 226 2.91 to 31.8, Thorium 232 1.4 to 14.9, Potassium 40 from 132 to 2080.

Newer granite   Radon 226  8.9 to 9087,  Thorium 232 9.8 to 3834, Potassium 40 from  471 to 10,230 

Highest values were Radon 226 9087, Thorium 232 3834 and Potassium 40 was 10,230 

"A pack a day smoker takes in 15 to 20 Bq per year"

Here is a link that gives some common values of radiation, my thanks to the stoners that brought it to light over at gardenweb.com

Look about halfway down, there is a chart of common materials and their Bq rates.  Granite is listed as 1000 Bq, apparently using a 4 ppm uranium content.   Some one check my math, please.

1000 bq per kilogram,   454 grams per pound, so roughly 2,000 Bq per pound of granite.  Average top is 75 square feet, or around 1,500 pounds of granite x 2,000 Bq = 15,000,000 Bq per kitchn top.   A three slab job, got one going on right now, will be 30,000,000 Bq not counting window sills, tile for backsplash and floors, vanities and other natural occuring radioactive materials like cement and drywall.

A kilogram of uranium is only 25,000,000 Bq......   And remember, always remember that  they quoted 4 ppm uranium content in the article.   Imagine having granite with 500 ppm, take that 30,000,000 and multiply it by 125 or around 30 Billion Bq, approaching mid level radioactive waste levels, low level waste is around 1 million Bq.

Why didn't the MIA article mention Thorium and Potassium in addition to the uranium? 

On this issue, they are really selling the maximum and are open to a FTC complaint.

Norm,

Radiation dose falls off by the inverse square of the distance to the source.  In other words, if you were twice as far away from the source, your effective dose would be reduced to 25%.  That would be like moving from one foot away to two feet away.

Dan Dauchess

I think i had some radon in my coffee today. tasted weird.

If you really want to convince people that they should not use granite  you are going about it all wrong.  Just put out a news release that states that it causes global warming.  Everyone seems to be buying into that story right now.  The information will then appear as scientific fact on all TV news, the LA Times will run a front page article, Fox will have debates with "experts" and talk radio will have another topic.

Did anyone else notice that the baby in the picture in that radon article is playing with solid surface squares? 

Linda

Tom,

The law of squares applies whether it's sunlight, radio waves, x-rays, gamma rays............

The health physics guys will tell you it all comes down to time, distance and shielding.

Dan

[QUOTE]FEDSAWDAVE wrote
Linda, How can you tell those are SS squares? I looked, must be my eyes. Kinda looks like Eng. Stone.[/QUOTE]

If that is any kind of natural stone, the solid surface industry had done a great job of copying the colors.  I have been looking at this stuff for years and there are solid surface colors that look just like those in the picture. 

Linda

Tom,

The law of squares applies whether it's sunlight, radio waves, x-rays, gamma rays............

The health physics guys will tell you it all comes down to time, distance and shielding.

Dan

Tom,

The law of squares applies whether it's sunlight, radio waves, x-rays, gamma rays............

The health physics guys will tell you it all comes down to time, distance and shielding.

Dan

[/QUOTE]

Watch people at a countertop, most tend to lean against it.    Right about family jewels level......  Or at a childs eye level.

Anyone see this months Surface Fabrication mag yet?   Got our own Mr Mory on the cover.    Also had a mention of a seven year old child being killed at a granite slab yard, killed by falling slabs while Mom and Dad were picking out slabs for their kitchen.

I am going to track that one down.

Received my copy as well but did not catch the slab yard tragedy.

1st off, no child should have been allowed in that yard. Period. I posted once before about a customer who lost several hundred slabs due to the forklift operator tapping one slab and a domino affect occurring. Other employees were running to get out of the way.

One of our regional solid surface reps was talking about this a week or so ago, what will happen when consumer injury or deaths become common in granite yards.   His point was that picking out your own slab might not be possible one of these days.

I agree, children have no business in a stone yard.

Good advice Dave... I raised 5 children and they are all succesfull adults now, taught them not to play in the street or on the freeway! Good parenting skills I guess.

Good advice Dave... I raised 5 children and they are all succesfull adults now, taught them not to play in the street or on the freeway! Good parenting skills I guess.

[/QUOTE]

I don't see how you can blame the kid, KD.

I am missing some posts or something. 

 But it is hard to imaging how the parents are not at fault. Are they dead?  Did the slab fall a few inches left or right of them?  If not they were clearly not in control of thier child.

I see it all the time, and noone understands why little johnny doesn't respect  the law when he grows up. It is because he was never taught the concept of Law as a child.