After warning us about the dangers of walking barefoot in the park (grass can cut your feet allowing parasites to enter your body, apparently), the Neurotic Times New York Times recently decided to investigate whether leaning on your granite countertop will give you lung cancer.
The problem is that natural stone can contain radioactive elements. Mother Earth, having been created in an enormous burst of energy, is, unfortunately, radioactive. As these radioactive elements decay, they release radiation in the form of rays; but if the element is uranium, it decays first into radium which in turn creates a gas called radon. If you breathe air containing radon you increase your risk for lung cancer. The risk exists wherever you build a house, which is why it is important to have your house tested, especially if you live in high radon areas.
But there’s a difference between the earth’s crust and a granite slab in your kitchen, and the question is can a granite countertop release enough radiation to pose a risk? The Times story begins with an anecdote about a pediatrician, Dr. Lynn Sugarman, telling her visiting pregnant daughter to stay away from the kitchen counter after a routine radon detection signaled radiation at ten times the level in the rest of the house. She then ripped out the granite countertop and sent it off for analysis: it turned out to contain high levels of uranium.
According to the Times, the radon readings in Dr. Sugarman’s kitchen were 100 picocuries per liter, compared to 6 picocuries per liter in her basement.
And this is where things become confusing. Both Consumer Reports and The Environmental Protection Agency suggest that fears about granite countertops have been overhyped – and Consumer Reports tracks some of the most damning information to rival, non-granite countertop manufacturers. There have been multiple tests of many different types of granite and emissions have been found, in almost all cases, to be negligible.
In a study of Cold Spring Granite Company building stone samples, for example, Daniel J. Steck, Ph.D. a physicist at St. John’s University, calculated the radon exposure from granite building materials in a range of typical dwellings and found that it amounted to less than 1 percent of the overall concentration in a home.
In fact, most of the Times article notes how much of a risk granite isn’t in terms of radiation and radon:
David J. Brenner, director of the Center for Radiological Research at Columbia University in New York, said the cancer risk from granite countertops, even those emitting radiation above background levels, is “on the order of one in a million.”
So how could Dr. Sugarman’s countertop sound like an atom bomb? In fact, if the ventilated air in the kitchen was registering 100 picocuries of radon per liter, Dr. Sugarman was absorbing a terrifying amount of radon – enough to raise her risk of getting lung cancer to one in seven, based on the EPA’s risk exposure guidelines. (And if she smoked on top of that, the statistical risk is a virtual guarantee that she would develop or should have already developed lung cancer).
That the Sugarman household was not hermetically sealed in a plastic bubble by the EPA suggests that the Times omitted some crucial information about how radon is emitted from stone, namely that it diffuses rapidly in air. In other words, the reading of 100 picocuries per liter is the emission rate but not the airborne concentration level. This is an important distinction. It’s also important to note that a cubic foot is 28 liters, so a 1,000 square foot home with ten foot high ceilings would contain over a quarter of a million liters of air. As Columbia’s Brenner told WebMD, “Even a countertop that is ten or a hundred times higher than average is going to constitute a minimal contribution of radon.”
Without knowing the airborne concentration level in Sugarman’s kitchen, it is impossible to know how much of an actual risk her countertop presented, and whether having it ripped out was an over-reaction; and this in turn speaks to the importance of how you measure risk and how you deploy anecdotes in journalism. The Sugarman countertop gives the story much needed drama, but only because it is presented in a way that exaggerates the risk.
But his cuts both ways: the other troubling question raised by the Times article is whether the air content measured in Dr. Sugarman’s basement was, in fact, 6 picocuries per liter; if so, then the EPA recommends she take action to fix her home immediately.