A new study suggests that non-smokers exposed to high levels of the radioactive gas radon in their homes have a certain genetic mutation about as often as smokers would.

Dr. Bryn Bridges, director of the preliminary study, said he was stunned by the finding but stressed that it came from a small sampling. He said the result could be due to a statistical fluke, chance or some cancer-causing agent.He plans to repeat the study, which involved 20 people, and if he gets the same results, launch a much larger investigation.

Many cancers are thought to be triggered by genetic mutations.