Article
Open Access
Published: 14 September 2022
Social factors and behavioural reactions to radon test outcomes underlie differences in radiation exposure dose, independent of household radon level
Jesse L. Irvine, Justin A. Simms, Natasha L. Cholowsky, Dustin D. Pearson, Cheryl E. Peters, Linda E. Carlson & Aaron A. Goodarzi
Scientific Reports volume 12, Article number: 15471 (2022) Cite this article
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Abstract
Radioactive radon gas inhalation causes lung cancer, and public health strategies have responded by promoting testing and exposure reduction by individuals. However, a better understanding of how radon exposure disparities are driven by psychological and social variables is required. Here, we explored how behavioural factors modified residential radon-related radiation doses incurred by 2390 people who performed a radon test. The average time from first awareness to receiving a radon test outcome was 6.8–25.5 months, depending on behaviour and attitudes. 20.5% displayed radon test urgency that reduced irradiation between awareness and outcome to 1.8 mSv from a typical 3.5 mSv, while 14.8% (more likely to be men) displayed delaying behaviours that increased exposure to 8.0 mSv. Of those with low radon, 45.9% indicated no future testing intention, underscoring the importance of original tests to reliably establish risk. Among people finding high radon, 38% mitigated quickly, 29% reported economic impediments, and 33% displayed delaying behaviours. Economic barriers and delaying behaviours resulted in 8.4 mSv/year or 10.3 mSv/year long term excess exposure, respectively, increasing lifetime risk of lung cancer by ~ 30–40%. Excess radiation doses incurred from behaviour were independent of household radon level, highlighting the strong influence of psychological and socioeconomic factors on radon exposure and lung cancer risks.
Introduction
Lung cancer is responsible for 1 in 4 cancer-related deaths in North America and Europe, and lung cancer in people who have never smoked is now the 7th leading cause of cancer-linked death globally1,2,3,4,5. Radioactive radon gas inhalation in the residential built environment is a principal cause of lung cancer, causing many thousands of new diagnoses per year, including populations who have never smoked tobacco 3,6,7,8,9,10,11,12,13,14,15. The long term inhalation of radon and its airborne decay progeny cause lung cancer by bombarding cells with alpha particle radiation 7,10,11,12,13,14,15,16. Because alpha radiation damages lung DNA to produce genetic mutations that elevate cancer risk, radon is a classified by the International Agency for Research on Cancer as a group 1 carcinogen, alongside tobacco, asbestos and air pollution particulate matter14,15,16. Levels of alpha particle radiation from radon within a building is measured in Becquerels (Bq) per cubic meter (m3), equal to one radioactive emission per second per cubic metre of air. When generalized across populations, there is an additive 16% increase in relative lifetime risk of lung cancer per 100 Bq/m3 of long term radon exposure17,18. To calculate absorbed radiation doses for individuals or small groups, however, Bq/m3 indoor air radon levels must be integrated with measures of exposure duration (hours per year breathing that air) to derive Sievert (Sv) doses of absorbed energy per mass. The global average alpha radiation exposure from residential radon is currently reported to be 1.2 mSv per year (mSv/year)19, but this varies by region and demographics9,20. Based on data obtained from the Canadian and American National Human Activity Pattern Study, the average North American adult spends 6018 h/year inside a residence21. Using the latest conversion formula standardized by the International Commission for Radiological Protection (ICRP), this would mean 100 Bq/m3 of residential radon equates with 4 mSv/year that increases relative lifetime risk of lung cancer by 16%. Allowing for a 10–30 year period of radon exposure prior to lung cancer diagnosis4,5,9,10,14, this estimates 40–120 mSv as the minimum range of absorbed alpha particle radiation from radon that is needed to increase lifetime lung cancer relative risk by the minimum statistically significant amount over the long term; this range is also in agreement with observations of radon-induced lung cancer using rodent models22.
It is important to note that prevalent, unsafe radon levels in indoor air is a modern, human-made problem largely rooted in the design of our built environment. Although radon is emanated by most of the Earth’s subsurface, through most of human history it is reasonable to hypothesize that it diluted naturally in the atmosphere, or was effectively vented from (predominantly non air-tight) buildings to low (< 100 Bq/m3) levels with no evident health impacts14. Regrettably, construction practices over the past century have produced urban and rural environments with buildings that capture, contain, and concentrate radon to unnatural and unsafe levels12,13,20,23. Residential radon gas levels continue to change over time, often as a function of evolving regional building trends. For example, new Canadian houses currently show 467% higher radon levels vs modern Swedish equivalents, although radon levels in mid-to-late twentieth century Canadian properties were either equivalent to or less than those in Sweden23. This scenario is thought to have arisen not from any identifiable, specific radon-related intervention, but rather as a collateral consequence of ever-changing and often diverging region-specific building practices.
Aside from building features or local geology, there are also social and economic factors that can influence how different populations are exposed to radon. For example, in many regions of North America, mid-to-late twentieth century properties with comparatively lower radon levels are less accessible to younger people due to high prices, biasing these individuals (particularly first time homeowners with small children) towards living in newer, more affordable communities that have higher radon levels and, thus, producing youth-skewed radon exposure trends driven by socioeconomics20. Public health organizations have responded to the global radon exposure crisis by broadly promoting awareness of radon health effects, and encouraging exposure reduction at the level of the individual home-owner3,6,7,8,9,10,11,12. Given that the onus is on the individual to act to reduce radon exposure, it is worth noting that typical radon and lung cancer risk communication approaches are not operating in an inclusive manner, with issues in messaging identified on the basis of ethnicity, region, education, age, sex, and profession24,25,26,27,28.
A majority of public radon-related health strategies focus on getting individuals to test buildings and personally invest in radon mitigation to remove risk. By relying solely on individual action, there is an inherent reliance on individual motivation and capability, influenced by socioeconomic factors and social determinants of health, to act to reduce the health threat of radon exposure29,30. This can result in inequitable exposure and hence increased risk for lung cancer in those groups less likely to take personal action to mitigate risk. More specifically, how long it takes someone to first become aware of radon, obtain a test, complete a test, or act (based on the outcome of a test), and whether they do (or are able to afford) any of this at all, are influenced by education, income, information processing capability, emotional reactions, and decision-making to both measure and remove radon as a source of lifetime lung cancer risk. Consider a simple example of a low income family in a basement rental unit struggling with food insecurity and medical expenses—checking and/or mitigating their radon exposure is unlikely to be prioritized above more fundamental needs. The influence of these factors on radon exposure, particularly on doses of alpha radiation experienced at an individual level, are not well understood. To address this, we assessed if emotional reactions, economic barriers, and decision-making following radon test outcomes differed between people who performed long term radon test, and how this impacted long term radiation exposure. Our main objective was to determine whether select social, economic, and behavioural differences were variables that modified radiation exposure, beyond baseline doses understood from household radon levels alone.
Abstract
Radioactive radon gas inhalation causes lung cancer, and public health strategies have responded by promoting testing and exposure reduction by individuals. However, a better understanding of how radon exposure disparities are driven by psychological and social variables is required. Here, we explored how behavioural factors modified residential radon-related radiation doses incurred by 2390 people who performed a radon test. The average time from first awareness to receiving a radon test outcome was 6.8–25.5 months, depending on behaviour and attitudes. 20.5% displayed radon test urgency that reduced irradiation between awareness and outcome to 1.8 mSv from a typical 3.5 mSv, while 14.8% (more likely to be men) displayed delaying behaviours that increased exposure to 8.0 mSv. Of those with low radon, 45.9% indicated no future testing intention, underscoring the importance of original tests to reliably establish risk. Among people finding high radon, 38% mitigated quickly, 29% reported economic impediments, and 33% displayed delaying behaviours. Economic barriers and delaying behaviours resulted in 8.4 mSv/year or 10.3 mSv/year long term excess exposure, respectively, increasing lifetime risk of lung cancer by ~ 30–40%. Excess radiation doses incurred from behaviour were independent of household radon level, highlighting the strong influence of psychological and socioeconomic factors on radon exposure and lung cancer risks.
Introduction
Lung cancer is responsible for 1 in 4 cancer-related deaths in North America and Europe, and lung cancer in people who have never smoked is now the 7th leading cause of cancer-linked death globally1,2,3,4,5. Radioactive radon gas inhalation in the residential built environment is a principal cause of lung cancer, causing many thousands of new diagnoses per year, including populations who have never smoked tobacco3,6,7,8,9,10,11,12,13,14,15. The long term inhalation of radon and its airborne decay progeny cause lung cancer by bombarding cells with alpha particle radiation7,10,11,12,13,14,15,16. Because alpha radiation damages lung DNA to produce genetic mutations that elevate cancer risk, radon is a classified by the International Agency for Research on Cancer as a group 1 carcinogen, alongside tobacco, asbestos and air pollution particulate matter14,15,16. Levels of alpha particle radiation from radon within a building is measured in Becquerels (Bq) per cubic meter (m3), equal to one radioactive emission per second per cubic metre of air. When generalized across populations, there is an additive 16% increase in relative lifetime risk of lung cancer per 100 Bq/m3 of long term radon exposure17,18. To calculate absorbed radiation doses for individuals or small groups, however, Bq/m3 indoor air radon levels must be integrated with measures of exposure duration (hours per year breathing that air) to derive Sievert (Sv) doses of absorbed energy per mass. The global average alpha radiation exposure from residential radon is currently reported to be 1.2 mSv per year (mSv/year)19, but this varies by region and demographics9,20. Based on data obtained from the Canadian and American National Human Activity Pattern Study, the average North American adult spends 6018 h/year inside a residence21. Using the latest conversion formula standardized by the International Commission for Radiological Protection (ICRP), this would mean 100 Bq/m3 of residential radon equates with 4 mSv/year that increases relative lifetime risk of lung cancer by 16%. Allowing for a 10–30 year period of radon exposure prior to lung cancer diagnosis4,5,9,10,14, this estimates 40–120 mSv as the minimum range of absorbed alpha particle radiation from radon that is needed to increase lifetime lung cancer relative risk by the minimum statistically significant amount over the long term; this range is also in agreement with observations of radon-induced lung cancer using rodent models22.
It is important to note that prevalent, unsafe radon levels in indoor air is a modern, human-made problem largely rooted in the design of our built environment. Although radon is emanated by most of the Earth’s subsurface, through most of human history it is reasonable to hypothesize that it diluted naturally in the atmosphere, or was effectively vented from (predominantly non air-tight) buildings to low (< 100 Bq/m3) levels with no evident health impacts14. Regrettably, construction practices over the past century have produced urban and rural environments with buildings that capture, contain, and concentrate radon to unnatural and unsafe levels12,13,20,23. Residential radon gas levels continue to change over time, often as a function of evolving regional building trends. For example, new Canadian houses currently show 467% higher radon levels vs modern Swedish equivalents, although radon levels in mid-to-late twentieth century Canadian properties were either equivalent to or less than those in Sweden23. This scenario is thought to have arisen not from any identifiable, specific radon-related intervention, but rather as a collateral consequence of ever-changing and often diverging region-specific building practices.
Aside from building features or local geology, there are also social and economic factors that can influence how different populations are exposed to radon. For example, in many regions of North America, mid-to-late twentieth century properties with comparatively lower radon levels are less accessible to younger people due to high prices, biasing these individuals (particularly first time homeowners with small children) towards living in newer, more affordable communities that have higher radon levels and, thus, producing youth-skewed radon exposure trends driven by socioeconomics20. Public health organizations have responded to the global radon exposure crisis by broadly promoting awareness of radon health effects, and encouraging exposure reduction at the level of the individual home-owner3,6,7,8,9,10,11,12. Given that the onus is on the individual to act to reduce radon exposure, it is worth noting that typical radon and lung cancer risk communication approaches are not operating in an inclusive manner, with issues in messaging identified on the basis of ethnicity, region, education, age, sex, and profession24,25,26,27,28.
A majority of public radon-related health strategies focus on getting individuals to test buildings and personally invest in radon mitigation to remove risk. By relying solely on individual action, there is an inherent reliance on individual motivation and capability, influenced by socioeconomic factors and social determinants of health, to act to reduce the health threat of radon exposure29,30. This can result in inequitable exposure and hence increased risk for lung cancer in those groups less likely to take personal action to mitigate risk. More specifically, how long it takes someone to first become aware of radon, obtain a test, complete a test, or act (based on the outcome of a test), and whether they do (or are able to afford) any of this at all, are influenced by education, income, information processing capability, emotional reactions, and decision-making to both measure and remove radon as a source of lifetime lung cancer risk. Consider a simple example of a low income family in a basement rental unit struggling with food insecurity and medical expenses—checking and/or mitigating their radon exposure is unlikely to be prioritized above more fundamental needs. The influence of these factors on radon exposure, particularly on doses of alpha radiation experienced at an individual level, are not well understood. To address this, we assessed if emotional reactions, economic barriers, and decision-making following radon test outcomes differed between people who performed long term radon test, and how this impacted long term radiation exposure. Our main objective was to determine whether select social, economic, and behavioural differences were variables that modified radiation exposure, beyond baseline doses understood from household radon levels alone.
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