Granite Countertops a Recipe for Danger?

Debate Heats Up About Radon Risks

Medically Reviewed by Louise Chang, MD on July 30, 2008
From the WebMD Archives

July 30, 2008 -- They are beautiful and durable, but do those pricey granite kitchen countertops so popular with home builders and renovators also pose a health risk?

Some researchers say they might, but a group representing the granite industry counters that those claims are “alarmist” and that their studies are little more than “junk science.”

At issue is whether some granite countertops emit dangerous levels of radiation, especially the gas radon, which is the second leading cause of lung cancer after smoking.

Experts agree that most granite countertops emit some radon and even other types of radiation. The question is whether they do so at levels that can impact cancer risk.

New York State Health Department research scientist Michael Kitto, PhD, says only a small fraction of the granite samples he has tested have emitted radon at levels that were over those considered safe.

But he added that a few of his samples showed levels that were high enough to alarm him.

“I wouldn’t have them in my house,” Kitto tells WebMD.

Countertop Concerns Not New

Concerns about the safety of granite kitchen countertops are not new.

“The countertop story emerges every 10 years or so,” Columbia University Center for Radiological Research Director David J. Brenner, PhD, tells WebMD. “This is about the third time I remember it coming around.”

The concerns were fueled by a New York Times story last Thursday examining the issue.

The story mentioned the research of Rice University physics professor William Llope, PhD, which found potentially dangerous levels of radiation in some tested samples of granite used in countertops.

In response to the Times article, the Marble Institute of America (MIA) issued a statement on its web site asserting that the Environmental Protection Agency agreed with the industry claim that studies like Llope’s represented “junk science.”

Under the headline “EPA Confirms that Granite Countertops Pose No Significant Health Risk, Undercutting ‘Junk Science’ Fear Mongering,” the article claims that the EPA issued a statement on Friday saying as much.

While confirming that a Q&A on the EPA web site addressing the radon and countertop issue was changed late last week, EPA spokesman Dave Ryan refused to discuss the institute's claim in an interview with WebMD.

“I will not comment on anything that they are saying,” he said. “All I will say is that our position is on the web site.”

That position, as of early this week, was much more nuanced than the institute claims, noting that “some granite used for countertops may contribute variably to indoor radon levels.”

“At this time, however, EPA does not believe sufficient data exist to conclude that the types of granite commonly used in countertops are significantly increasing indoor radon levels,” the statement reads.

In response to the question, “Are the levels of radon in granite dangerous to humans or animals?” the EPA states, “While radon levels attributable to granite are not typically high, there are simply too many variables to generalize about the potential health risks inside a particular home that has granite countertops.”

Little Cause for Alarm, Expert Says

Columbia’s Brenner believes it is highly unlikely that granite countertops emit enough radon to pose a health risk because they cover such a small area.

“The biggest source of radiation within the home is indeed radon,” he says. “But it is not radon from countertops, it’s radon from the ground.”

Radon is an odorless, tasteless, colorless radioactive gas that results from the natural decay of uranium in soil, rock, and water. All agree that the biggest risk to homeowners is radon seeping into homes from the ground.

Most people living in areas with high radon concentrations, such as New Jersey, Pennsylvania, and upstate New York, are very aware of the potential risk, Brenner says.

“You can’t get a mortgage in New Jersey without having a radon test,” he says. “If radon is above a certain level, you have to take action.”

The risk from radon comes from breathing it into your lungs, and Brenner says any radon coming from granite countertops would quickly diffuse into the air.

“Even a countertop that is ten or a hundred times higher than average is going to constitute a minimal contribution of radon.”

Others Believe Fears Are Justified

But Rice University’s Llope is not so sure.

Llope tells WebMD that he began testing granite samples “on his own time” after seeing a story about granite countertops and radon on a Houston news program.

He tests for gamma radiation emission using a special spectrometer.

In a recently published review of radon tests conducted by others, Llope reported that 92 of 95 granite samples tested emitted no radon or very little radon. Two samples emitted levels that were elevated but still considered safe, and one emitted levels slightly above what is considered cause for concern by EPA.

Like Kitto, Llope has found elevated levels in a very small number of the granite samples he has personally tested.

But he tells WebMD that if even a tiny percentage of the granite used to make countertops emits unsafe levels of radon or other radiation, that could represent a danger in thousands of homes.

“Granite has gotten so popular so quickly that it is now coming from all over the world,” he says. “It would come as no surprise that granite that comes from areas with uranium mines close by might pose a problem. But the testing hasn’t been done.”

More Granite Testing Needed

According to Marble Institute of America spokesman Jim Martinez, 2,000 different stones from quarries around the world are sold as granite in the United States.

At most, only a tiny percentage of them have been tested for radon or radiation levels, but a recent test of 13 types of granite typically used for countertops found no radon or very low levels of radon.

The test was paid for by the MIA, and the samples represented 85% of the granite used for kitchen countertops in the United States, Martinez says.

He says that the MIA-funded research represents the only “real” science examining the issue, because no one else has been willing to pay for quality studies.

“(Our) studies have consistently shown that granite poses no heath risk,” he says.

But Kitto says there is no way to know if all granite countertops are safe because so few samples have been tested.

“Right now, it is impossible to understand the scope of the problem or even if there is a problem,” he says.

Llope agrees that more samples need to be tested.

“The industry says there is no danger, but how can they make that leap of faith when granite is coming from all over the world and only a small percentage has been tested?” he says. “How can they possibly know?”

Test for Radon, Experts Say

The EPA recommends that all homes be tested for radon in indoor air, and the researchers contacted by WebMD agreed that testing could provide peace of mind to homeowners worried about the safety of their granite countertops.

Recommendations for using do-it-yourself radon testing kits, which can be purchased at hardware stores and online, include:

  • Place one test in the basement or lowest area in the home to determine if radon is coming from the ground.
  • Place another test in a bedroom to establish a background radon level.
  • Place one or two tests in the kitchen, with one nearby the granite surface and the other farther away.

“The home kits test for radon, not (other) radiation; but if the findings are negative you can assume you don’t have a radiation problem,” Llope says. “If the results come back positive, you should probably have the house tested professionally.”

The American Association of Radon Scientists and Technologists lists the names of qualified professionals who conduct radon and radiation testing on its web site,

Show Sources


EPA: “What about Granite Countertops?” revised July 29, 2008.

David J. Brenner, PhD, professor of radiation oncology and public health; director, Center for Radiological Research, Columbia University, New York.

Michael Kitto, PhD, research scientist, New York State Department of Health.

William J. Llope, PhD, research associate professor of physics, senior faculty fellow, T.W. Bonner Nuclear Laboratory, Rice University, Houston.

David Ryan, spokesman, Environmental Protection Agency.

Jim Martinez, spokesman, Marble Institute of America.

“What’s Lurking in Your Countertops,” New York Times, July 24, 2008.

EPA web site: "A Citizen's Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon."

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