Posted for Katrina Charles, BA Media Fellow
There has been a lot of press in the USA in the last few days about the risk from radiation from granite countertops. Rice University physics professor William Llope says 3 out of 95 samples of granite he’s looked at had radiation levels above US EPA guidelines, although his data is as yet unpublished (Houston Chronicle).
Granite and other volcanic rocks are known to have higher than average levels of uranium. As uranium decays one of the things you’ll find in its place is radon gas. Inhaling this gas is unsurprisingly bad for your lungs’ health.
So if there are high levels of uranium in the granite used for countertops, they can give off high levels of radon. While marble manufacturers are citing the EPA assurances that granite countertops pose no significant health risk, some people are already ripping them out (NY Times).
Radon is well known to be a problem when it builds up. Underground, it can build up in caves and mines. In houses, it can build up if the house isn’t properly ventilated.
The Marble Institute of America (which also backs granite producers) got the University of Akron, Ohio, to test 13 types of granite used in benchtops. Akron’s researchers found the granite with the highest level of radiation would contribute 0.27 picoCuries (pCi) per litre to a household, where the levels requiring action for a household in the US are 4 pCi per litre.
Given the high variability between granites, is there a granite with high enough emissions to cause health impacts when used for countertops? One kitchen where a benchtop was ripped out was reported to have levels of 100 pCi.per Litre, 25 times higher than the action level. However, the basement, which presumably reflects the natural levels in local rocks, was also over the action limit with 6 pCi per Litre.
And while the danger from granite is low, if it’s there at all, a line in the NY Times’ coverage suggests we could be seeing a lot more stories on the topic: “Personal injury lawyers are already advertising on the Web for clients who think they may have been injured by countertops.”
Image: granite quarry in Maine circa 1906 / USGS