Cathy Woods’ new granite counters were radioactive. They contained as much uranium as commercial uranium ore. The showroom that sold Cathy her Jupurana Bordeaux granite did not warn her that some granite is radioactive.

When I contacted the salesman, posing as a customer, he assured me their granite “is no more radioactive than soil or water”. However, Cathy’s granite emitted gamma radiation at many times background. The radon gas emitted by the stone tripled the radon concentration in her kitchen.

Jupurana Bordeaux is one of the granites that are likely to be radioactive. Just weeks after having her counters installed, Cathy learned of the possibility and enlisted the assistance of professionals to assess her exposure to radiation and radon gas.

Radon is a daughter product of uranium, so granites containing uranium will emit radon. According to the EPA, radon is the leading cause of lung cancer in non-smokers. Cathy and her husband both have family histories of cancer, so they were very concerned about elevated radiation and radon in their kitchen.

Some granite quarries are near uranium mines. Most granite does not contain large amounts of uranium, but some granite can have more uranium than a homeowner would want in the home. Cathy and I measured radiation from about 1,000 slabs of granite in showrooms around the San Francisco Bay Area. Most of the granite was only slightly radioactive. However, a small percentage emitted gamma radiation (penetrating radiation) at many times background.

We found Jupurana Bordeaux emitting gamma radiation at nearly 100 times background in the very showroom that claimed none of their stone was radioactive. When Cathy confronted the owner about his granite, he said he had no intention of warning buyers.

Cathy fell in love with Volga Blue granite to replace her Jupurana Bordeaux. It is mostly black with shiny crystals and iridescent “blue eyes”. Gamma emission was barely above background, one of the least radioactive granites we had seen.

We were left with many questions about radioactive granite we saw in showrooms. How much radioactive granite is installed in homes? How many of those homes have young children or pregnant women? Why don’t granite showrooms warn their customers?