Occasionally the question arises about whether Granite is radioactive. A homeowner or renter may come across an alarming video that shows a Geiger counter ticking wildly as it nears a stone countertop. Understandably, such videos can make someone question the safety of their countertops or the granite they were planning to purchase. But these videos are meant to alarm and they’re grossly misleading.
Yes, granite can be slightly radioactive, but the real question is whether it is radioactive enough to pose a danger. The answer to that question is no, it is not dangerous. Granite is not likely to cause anyone harm or significantly contribute to a home’s radon levels.
Is Granite Harmful to Your Health?
To be clear, granite is about as radioactive as the banana in your fruit bowl, and far less radioactive than the soil on which your home sits.
The fact is that all minerals and stones, including those found in most types of granite, are somewhat radioactive. In addition, many fertilizers and soils are also radioactive, as are the fruits and vegetables grown with those fertilizers and in those soils. On our planet, we are surrounded by radiation from the sun, machines, airplanes, the soil, medical devices, watches, etc. We cannot hide from it, at least not easily.
Because radioactivity is so pervasive on Earth – and even in the average home – it’s expected that the average person will be exposed to a certain amount of radiation each year. Problems occur, such as cancer risk, when that average is significantly exceeded.
What Makes Granite Radioactive?
The minerals present in all-natural stones contain very small amounts of the radioactive elements, uranium, thorium and potassium-40. Some of these elements can decay into radon gas over time. Granite naturally contains more of these elements than many other stones and is therefore a little bit more radioactive than other natural surfaces, such as slate or marble. But the radiation levels are still extremely low compared to the amount of radiation people are exposed to from other sources over the normal course of a year.
According to the U.S. Environmental Protection Agency (EPA), the amount of radon emitted by granite is minimal enough that a normal home’s ventilation system will dilute and disperse it before it can accumulate. Direct exposure to radiation by surface contact is also unlikely and diminishes rapidly with distance – and by distance, think inches, not feet. Absorption by food is not a problem either, because the food would need to absorb the granite and granite is not water soluble, according to the Marble Institute of America.
If a person sat directly on a granite countertop and did not move for an entire year, the amount of radiation they would be exposed to would equal about a quarter of a person’s annual average exposure to all types of radiation, including the sun, x-rays, and airplanes. If they stood a few inches from the stone for the same amount of time, the amount of exposure would be too low to measure, the Marble Institute of America explains in an article on its website.
Do Granite Countertops Produce Radon Gas?
There’s no doubt that radioactivity is a home hazard that people should be aware of, because some radioactive materials can decay into radon. Soil, for instance, often contains small amounts of uranium, which decays into radium, and finally radon gas. Radon gas is a known issue in homes as a contributing cause for lung cancer. The primary risk, however, is due to geography, not the contents of the home or the countertops. Areas of the country where soils contain elevated levels of uranium are where radon gas accumulation in homes is common and can become dangerous.
The federal standard for home radon levels is 4 pCi/L (4 picocuries per liter of air). The EPA recommends homeowners try to reduce radon in their home if levels are at or above 4 pCi/L and to consider taking actions to reduce the levels if they are over 2 pIC/L. It’s disputed whether the EPA standard is aggressive enough, but even experts who think the federal standard is too lax don’t think it makes any sense to test granite for radioactivity. One such organization and distributor of radon test kits, Air Chek, Inc., said on their website that they performed tens of thousands of tests on granite countertops and never once found a slab that produced dangerous levels of radon gas. The organization considers it “a disservice” to its customers to offer tests for granite, even when requested.
Experts who check homes for radon emissions, don’t target specific items within the home, like a granite countertop. They test the ambient air to determine whether there’s a problem.
Air Chek, Inc. also pointed out on its site that they have seen some very misleading Geiger counter demonstrations singling out granite as a source of radiation. The company gave two reasons why Geiger counters are not appropriate for measuring radon from granite. First, the Geiger counters are not calibrated to detect radon. They detect many other forms of radiation in addition to Radium, which is the main element responsible for the emission of the radon gas people worry about. Other radioactive elements, such as potassium, will set off a Geiger counter too and potassium is an essential nutrient found in many foods, including bananas.
Keeping Your Home Safe
People concerned about radon in their homes should get their homes tested. Kits are available from organizations like Air Chek, Inc., or residents in Florida can get a free test kit from the state http://www.floridahealth.gov/environmental-health/radon/Outreach/testkitrequest.html. One in 4 homes in Florida have radon levels above 4pCi/L, according to the Florida Department of Health.
Although radiation can become a problem in homes in Florida and across the US, the culprit is not granite. It’s more likely the soil beneath the foundation of a home, than the contents inside.
The bottom line is that radiation levels in natural stone countertops and many other natural products are simply not a cause for concern – at least not for most people, including children and elderly. If homeowners are worried, the best bet is to get a radon test and check radon levels within the ambient air of the home as a whole.