Q. We're thinking of replacing the countertops in our house with ones made of granite. However, one of our friends mentioned that she had heard that granite countertops can produce radon. We've tried to find some information on this subject but have been stumped, and obviously want to find out more about it before we go ahead and have new countertops put in. What's the story on radon in granite countertops? M.W. Plainwell.
A. You could hardly have picked a more controversial subject. While this issue has increasingly been in the news lately, it's hard to get an accurate bead on exactly what the potential dangers are, and whether many of the opinions that abound--generated by synthetic countertop material trade organizations, stone affiliates, independent researchers and others--have merit.
There is a lot at stake here. There is a huge, world-wide stone countertop industry, and millions of square feet of granite have been installed in homes in the past couple of decades. Because of its durability and beauty, stone is in many respects an ideal countertop material. But does that functionality and pulchritude come at the price of health?
Before getting into that, it is important to understand that we live in a world that contains "natural" background levels of both radiation and radon gas (the result of the breakdown of uranium in rock, soil or water). We're exposed to it, in various concentrations depending on where we are and what we're doing, every day. Both radiation and radon gas cause cancer. Statistically speaking, the higher your exposure level the more likely it is you will develop cancer. The ideal would be to have zero exposure. That's impossible, so the more realistic goal is to minimize exposure whenever possible.
What seems beyond dispute is that some varieties of granite do emit radon gas and radiation. Granite slabs from Brazil and Namibia in particular, as well as others, have been tested and found to emit both radiation and radon gas. Some granite has radiation "hot spots" here and there. Others show virtually nothing.
The US Environmental Protection Agency publishes radiation and radon gas exposure information and recommends levels not to exceed. For radon, the recommendation is that homes with concentrations of more than 4.0 picocuries per liter of air undergo remediation measures in order to reduce exposure. Most radon found in a home usually infiltrates via the basement. However, although the EPA states that "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," a granite countertop that emits radon will increase the overall level of the gas in the house.
The take-away from this is that every home should be tested for radon--regardless of countertop material. In addition, homes also need to be properly ventilated to reduce build-up of radon and other harmful pollutants that affect indoor air quality.
Ventilation and radon remediation, however, will do nothing to mitigate exposure to radiation coming from stone that contained radiation-emitting materials. Some stone dealers and distributors have started to test the material they sell for both radiation and radon. It would be worth asking the company you're considering for doing the countertop work on your home if it has such procedures in place--or if they know if the suppliers they get their stock from do.