University of Calgary scientists are asking Canadians to send in their toenail clippings — part of a nationwide study exploring how exposure to radon gas may contribute to lung cancer. “We’ve learned that our toenails hold long-term information about our exposure to radioactive toxicants in our environment such as radon gas,” said Dr. Aaron Goodarzi, a professor at the Cumming School of Medicine. “They are one of our body’s archives of past exposure.” Goodarzi leads an interdisciplinary research team studying environmental causes of lung cancer. Their latest work suggests toenails can help estimate a person’s long-term exposure to radon — a colourless, odourless gas that is the second-leading cause of lung cancer after smoking. “When you breathe in radon gas, it’s radioactive, and it transitions from a gas into a solid,” he said. “It very quickly becomes solid radioactive lead. Our bodies process that just like they do all lead — it goes to things like our hair, our skin and our nails.” But among those tissues, Goodarzi says toenails provide the most reliable record. “Your fingernails will grow twice as fast as your toenails,” he said. “That means the toenails are a better readout of your longer-term exposures — twice as better. “Another reason is our fingernails see that much more stuff — they’re doing the dishes, they’re encountering chemicals at work, they’re using cleaning products. For all of those reasons, toenails are where it’s at.” Goodarzi’s team recently completed a five-year-long pilot study on about 40 Canadians, comparing toenail samples from participants living in homes with high and low radon levels. “We asked the question, did the amount of radioactive lead in their toenails actually correspond to high versus low? And the answer is, it did,” he said. Now, with new funding from the Canadian Cancer Society, the researchers are expanding their work to 10,000 participants across the country. “We’ve got about 5,000 already,” said Goodarzi. “We’re looking for another 5,000 Canadians, evenly balanced across the nation.” Participants will receive radon test kits and be asked to collect four months’ worth of toenail clippings. Melting down the science Dr. Michael Wieser, a physics professor at the University of Calgary and co-investigator on the project, said toenail samples offer a surprisingly effective way to detect long-term radon exposure. His role involves taking the toenail samples and analyzing them using a method called isotope dilution mass spectrometry. “So in the lab, we take the toenails, we melt them down, dissolve them and then we run them through an instrument called a mass spectrometer,” he said. “It uses plasma to break down the sample, and then we can measure the isotopic composition of the lead that’s in there. That allows us to see if there’s radioactive lead that has come from radon decay.” Weiser added that incredibly small amount of lead can be detected – a femtogram amount – which is equal to one quadrillionth of a gram. “It’s exciting to apply these physics-based tools to something that can really impact people’s lives,” he added. “If we can detect radon exposure earlier, we might be able to help prevent cases of lung cancer that we currently can’t predict.” Finding hope through research Emi Bossio was diagnosed with lung cancer in 2019 at the age of 47 to her complete surprise. “I never smoked, ever. I ate well, stayed fit, and checked the chemicals in my cosmetics,” Bossio said. “There are no words to describe the shock when you hear those words: you have lung cancer.” The Calgary woman added that studies like this however give her a sense of optimism for those battling the same type of cancer. “It gives me hope that one day fewer people will be blindsided by this diagnosis,” she said. “Anything we can do to identify those risk factors is critical for the future of lung cancer.” Tim Monds, a non-smoker from Edmonton who was diagnosed with lung cancer in 2016, said he believes the study could also make a lasting impact. “This study is absolutely exciting for us to look at what causes lung cancer and another way of screening testing,” said Monds. “It will add another dimension of finding out the reasons people are getting lung cancer and a way for us to maybe find out earlier.” He said the ongoing research offers hope new opportunities for survival. Goodarzi says if the larger trial confirms their findings, the toenail method could one day change how doctors also determine lung cancer risk. “If all of that works, we should have the ability to add in a person’s long-term radon exposure to the criteria used right now to assess a person’s risk to decide whether they need a lung cancer screen or not,” he said. “And if we can do that, many more Canadians who need early diagnosis for lung cancer will be able to achieve that in our future.” Full details of the study and how to participate can be found online.
