Radon gas exposure is the cause of 16% of all new lung cancer diagnoses and the leading cause of lung cancer in non-smokers. Radon gas is a colorless, odorless radioactive gas that emanates from the ground and is captured and contained in our built environments (homes, workplaces, etc) leading to potentially cancer causing, high exposure to this toxic gas over an individual’s life. Lung cancer risk from radon is directly proportional to the amount (dose) of radiation that a person is exposed to throughout their lifetime. There is no way to effectively and reliably determine an individual’s personal lifetime exposure to radon. In this work, I will present on a preliminary study that explored measuring a marker of radon exposure, ²¹⁰Pb, which is a radioactive decay product that collects in the body, as a proxy for radon exposure. The goal of our study was to assess the amount of ²¹⁰Pb present in toenail samples of individuals with known radon exposure. Isotope dilution methods were used to quantify trace amounts of ²¹⁰Pb, as well as the total Pb content, in toenail clippings collected over a 3-month period from 67 individuals.   
Preliminary results show a correlation between the ²¹⁰Pb amount (normalized to the total Pb) measured in the toenails and lifetime radon exposure, calculated using known radon exposure levels in the home combined with detailed activity patterns of the individuals. For individuals in a high radon environment, the average ratio of the amount of ²¹⁰Pb to total Pb was 0.298 fg/ng, compared to those individuals in a low radon environment where the value dropped to 0.075 fg/ng. Upon the basis of this preliminary study, we will now be expanding the dataset to include thousands of Canadians to investigate the potential of this approach to predict radon exposure and the associated lung cancer risk.