Lung cancer as adverse health effect by indoor radon exposure in China from 2000 to 2020: A systematic review and meta-analysis

Indoor radon exposure is thought to be associated with adverse health effect as lung cancer. Lung cancer incidences in China have been the highest worldwide during the past two decades. It is important to quantitively address indoor radon exposure and its health effect, especially in countries like China. In this paper, we have conducted a meta-analysis based on indoor radon and its health effect studies from a systematic review between 2000 and 2020. A total of 8 studies were included for lung cancer. We found that the relative risk (RR) was 1.01 (95% CI: 1.01-1.02) per 10 Bq/m³ increase of indoor radon for lung cancer in China. The subgroup analysis found no significant difference between the conclusions from the studies from China and other regions. The health effect of indoor radon exposure is relatively consistent for the low-exposure and high-exposure groups in the subgroup analysis. With a better understanding of exposure level of indoor radon, the outcomes and conclusions of this study will provide supports for next phase of researches on estimation of environmental burden of disease by indoor radon exposures in countries like China.

A prospective cohort analysis of residential radon and UV exposures and malignant melanoma mortality in the Swiss population

BACKGROUND

Radon is a radioactive noble gas naturally found in the earth crust that can accumulate in buildings. In addition to lung cancer, alpha particles emitted by radon may contribute to the risk of skin cancer. We evaluated the association between residential radon exposure and skin cancer mortality, over a fifteen year period, taking residential ultra-violet (UV) exposure into account.

METHODS

We included 4.9 million adults from the Swiss National Cohort. Hazard ratios for melanoma mortality were estimated using Cox proportional hazard models (20+ years old; follow-up 2001-2015). Long-term modelled residential radon and ambient UV exposures were assigned at baseline, and included together in the Cox models. With age as a time scale, models were adjusted for calendar time, sex, marital status, education, mother tongue, socioeconomic position, and occupational environment with potential for UV exposure. Age specific hazard ratios were derived. Effect modification, sensitivity analyses and the shape of the exposure response, as well as secondary analysis using other outcome definitions, were investigated.

RESULTS

During follow-up (average of 13.6 years), 3,979 melanoma deaths were observed. Associations declined with age, with an adjusted hazard ratio per 100 Bq/m³ radon at age 60 of 1.10 (95% CI: 0.99, 1.23). The dose-response showed an approximate linear trend between the minimum and mean radon exposure of 75 Bq/m³. Having outdoor occupation significantly increased the risk of melanoma mortality associated with UV exposure compared to indoor jobs. Analysis restricted to the last five years of follow-up showed similar results compared to the main analysis. Similar associations were found for mortality from melanoma and non-melanoma skin cancer combined.

CONCLUSION

With double the follow-up time, this study confirmed the previously observed association between residential radon exposure and melanoma and non-melanoma skin cancer mortality in Switzerland. Accumulation of radon indoors is preventable and of public health importance.

Nonmalignant respiratory disease mortality in male Colorado Plateau uranium miners, 1960-2016

BACKGROUND

To evaluate trends of nonmalignant respiratory disease (NMRD) mortality among US underground uranium miners on the Colorado Plateau, and to estimate the exposure-response association between cumulative radon progeny exposure and NMRD subtype mortality.

METHODS

Standardized mortality ratios (SMRs) and excess relative rates per 100 working level months (excess relative rate [ERR]/100 WLM) were estimated in a cohort of 4021 male underground uranium miners who were followed from 1960 through 2016.

RESULTS

We observed elevated SMRs for all NMRD subtypes. Silicosis had the largest SMR (n = 52, SMR = 41.4; 95% confidence interval [CI]: 30.9, 54.3), followed by other pneumoconiosis (n = 49, SMR = 39.6; 95% CI: 29.6, 52.3) and idiopathic pulmonary fibrosis (IPF) (n = 64, SMR = 4.77; 95% CI 3.67, 6.09). SMRs for silicosis increased with duration of employment; SMRs for IPF increased with duration of employment and calendar period. There was a positive association between cumulative radon exposure and silicosis with evidence of modification by smoking (ERR/100 WLM≥10 pack-years  = 0.78; 95% CI: 0.05, 24.6 and ERR/100 WLM<10 pack-years  = 0.01; 95% CI: -0.03, 0.52), as well as a small positive association between radon and IPF (ERR/100 WLM = 0.06, 95% CI: 0.00, 0.24); these associations were driven by workers with prior employment in hard rock mining.

CONCLUSIONS

Uranium mining workers had excess NMRD mortality compared with the general population; this excess persisted throughout follow-up. Exposure-response analyses indicated a positive association between radon exposure and IPF and silicosis, but these analyses have limitations due to outcome misclassification and missing information on occupational co-exposures such as silica dust.

A global burden assessment of lung cancer attributed to residential radon exposure during 1990-2019

This study aimed to explore the spatial and temporal trends of lung cancer burden attributable to residential radon exposure at the global, regional, and national levels. Based on the Global Burden of Disease Study (GBD) 2019, we collected the age-standardized mortality rate (ASMR) and age-standardized disability-adjusted life rate (ASDR) of lung cancer attributable to residential radon exposure from 1990 to 2019. The Joinpoint model was used to calculate the annual average percentage change (AAPC) to evaluate the trend of ASMR and ASDR from 1990 to 2019. The locally weighted regression (LOESS) was used to estimate the relationship of the socio-demographic index (SDI) with ASMR and ASDR. In 2019, the global ASMR and ASDR for lung cancer attributable to residential radon exposure were 1.03 (95% CI: 0.20, 2.00) and 22.66 (95% CI: 4.49, 43.94) per 100 000 population, which were 15.6% and 23.0% lower than in 1990, respectively. According to the estimation, we found the lung cancer burden attributable to residential radon exposure declined significantly in high and high-middle SDI regions, but substantially increased in middle and low-middle SDI regions from 1990 to 2019. Across age and sex, the highest burden of lung cancer attributable to residential radon exposure was found in males and elderly groups. In conclusion, the global burden of lung cancer attributable to residential radon exposure showed a declining trend from 1990 to 2019, but a relatively large increase was found in the middle SDI regions. In 2019, the burden of lung cancer attributable to residential radon exposure remained high, particularly in males, the elderly, and high-middle SDI regions compared with other groups.

INFLUENCE OF AIRWAY GEOMETRY ON RADON RISK ASSESSMENT IN ADULTS AND CHILDREN (MICRODOSIMETRIC APPROACH)

The aim of this work was to use the microdosimetric threshold energy model to study the effects of alpha-emitting 222Rn progeny on the probability of developing lung cancer. The results suggest that the radiation risk may increase by several times as the thickness of the surface layer decreases. The thicker the protective mucus layer and the deeper the sensitive target cells are located in the tissue, the less radiation damage the same dose produces. These findings have been applied to children of various ages. As children grow older, their lungs enlarge, the mucus layer thickens and the cells sensitive to radiation damage move deeper into the lung tissue, resulting in a reduction of radiation risk. The fraction of affected target cells is not only a function of dose but also of lung tissue depth. The results indicate that children can be several times more vulnerable to radiation than adults.

Social Determinants of Health, Environmental Exposures and Home Radon Testing

Home radon testing is a primary lung cancer prevention strategy, yet the majority of Americans have not tested their home. This descriptive, ecological study uses 54,683 observed radon values collected in Kentucky homes from 1996 to 2016 to examine the association of county-level social determinants of health and environmental exposures on home radon testing rates. Multivariate linear regression analysis indicates that as median home value, rurality, and radon risk potential increased, counties experienced an increase in annual home radon testing rates. As adult smoking prevalence increased, counties experienced a decrease in annual rates of residential radon testing. These findings indicate that counties with low median home values, high adult smoking prevalence, and high incidence of lung cancer may benefit most from prevention interventions aimed at promoting home radon testing, adopting radon- and smoke-free home policies, and integrating radon risk reduction messaging into tobacco cessation and lung cancer screening programs.

A Systematic Review of Associations between Energy Use, Fuel Poverty, Energy Efficiency Improvements and Health

Energy use in buildings can influence the indoor environment. Studies on green buildings, energy saving measures, energy use, fuel poverty, and ventilation have been reviewed, following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The database PubMed was searched for articles published up to 1 October 2020. In total, 68 relevant peer-reviewed epidemiological or exposure studies on radon, biological agents, and chemicals were included. The main aim was to assess current knowledge on how energy saving measures and energy use can influence health. The included studies concluded that buildings classified as green buildings can improve health. More efficient heating and increased thermal insulation can improve health in homes experiencing fuel poverty. However, energy-saving measures in airtight buildings and thermal insulation without installation of mechanical ventilation can impair health. Energy efficiency retrofits can increase indoor radon which can cause lung cancer. Installation of a mechanical ventilation systems can solve many of the negative effects linked to airtight buildings and energy efficiency retrofits. However, higher ventilation flow can increase the indoor exposure to outdoor air pollutants in areas with high levels of outdoor air pollution. Finally, future research needs concerning energy aspects of buildings and health were identified.

Cure or Carcinogen? A Framing Analysis of European Radon Spa Websites

Objectives: Radon, a radioactive gas, is among the leading causes of lung-cancer worldwide. While public health authorities emphasize radon’s health risks, there are spas across Europe which claim health benefits of radon. This study investigates how websites of European radon spas frame radon gas, in order to understand the potential controversy between “radon as carcinogen” and “radon as cure,” and its potential impact on public health interventions.

Methods: A two-phased frame analysis of websites of radon spas (n = 26) situated in the European Union.

Results: Five frames are identified, which present radon as a 1) source of health, 2) natural gas, 3) (non) risk, 4) luxury and 5) fountain of youth. These five partly overlapping frames are at times in clear contrast with the ways in which radon is presented in a public health context.

Conclusion: Being aware of the existence and contents of radon frames, which potentially challenge or contradict public health interventions, helps responsible authorities in designing more effective campaigns and interventions.

Radon, Tobacco Exposure and Non-Small Cell Lung Cancer Risk Related to BER and NER Genetic Polymorphisms

INTRODUCTION

Tobacco consumption and radon exposure are considered the first and second most common causes of lung cancer, respectively. The aim of this study was to analyze both whether selected genetic polymorphisms in loci that are in DNA repair pathways, are related to non-small-cell lung cancer (NSCLC) and whether they may modulate the association between residential radon exposure and lung cancer in both smokers and never smokers.

METHODS

A multicentre, hospital-based, case-control study with 826 cases and 1201 controls was designed in a radon-prone area. Genotyping was determined in whole blood and residential radon exposure was measured in participants' dwellings.

RESULTS

Attending to tobacco exposure, the variant in the gene NBN (rs1805794) was associated with lung cancer in never smokers (OR 2.72; 95%1.44-5.2) and heavy smokers (OR 3.04; 95%CI 1.21-7.69). The polymorphism with the highest lung cancer association was OGG1 (rs125701), showing an OR of 8.04 (95%CI 1.64-58.29) for its homozygous variant genotype in heavy smokers. Attending to indoor radon exposure (>200Bq/m3), rs1452584, for its homozygous variant genotype, showed the highest association (OR 3.04 (95%CI 1.15-8.48).

CONCLUSION

The genes analyzed seem to have no association with the fully adjusted model, but they might modulate lung cancer association when different categories of tobacco consumption are considered (i.e. heavy smokers). This association may similarly be elevated for those individuals having high indoor radon exposures, though at a minor extent.

Impacts of Indoor Radon on Health: A Comprehensive Review on Causes, Assessment and Remediation Strategies

Indoor radon exposure is raising concerns due to its impact on health, namely its known relationship with lung cancer. Consequently, there is an urgent need to understand the risk factors associated with radon exposure, and how this can be harmful to the health of exposed populations. This article presents a comprehensive review of studies indicating a correlation between indoor radon exposure and the higher probability of occurrence of health problems in exposed populations. The analyzed studies statistically justify this correlation between exposure to indoor radon and the incidence of lung diseases in regions where concentrations are particularly high. However, some studies also showed that even in situations where indoor radon concentrations are lower, can be found a tendency, albeit smaller, for the occurrence of negative impacts on lung cancer incidence. Lastly, regarding risk remediation, an analysis has been conducted and presented in two core perspectives: (i) focusing on the identification and application of corrective measures in pre-existing buildings, and (ii) focusing on the implementation of preventive measures during the project design and before construction, both focusing on mitigating negative impacts of indoor radon exposure on the health of populations.

Lung and extrathoracic cancer incidence among underground uranium miners exposed to radon progeny in the Příbram region of the Czech Republic: a case-cohort study

OBJECTIVES

Radon is carcinogenic, but more studies are needed to understand relationships with lung cancer and extrathoracic cancers at low exposures. There are few studies evaluating associations with cancer incidence or assessing the modifying effects of smoking.

METHODS

We conducted a case-cohort study with 16 434 underground uranium miners in the Czech Republic with cancer incidence follow-up 1977-1996. Associations between radon exposure and lung cancer, and extrathoracic cancer, were estimated with linear excess relative rate (ERR) models. We examined potential modifying effects of smoking, time since exposure and exposure rate.

RESULTS

Under a simple ERR model, assuming a 5-year exposure lag, the estimated ERR of lung cancer per 100 working level months (WLM) was 0.54 (95% CI 0.33 to 0.83) and the estimated ERR of extrathoracic cancer per 100 WLM was 0.07 (95% CI -0.17 to 0.72). Most lung cancer cases were observed among smokers (82%), and the estimated ERR of lung cancer per 100 WLM was larger among smokers (ERR/100 WLM=1.35; 95% CI 0.84 to 2.15) than among never smokers (ERR/100 WLM=0.12; 95% CI -0.05 to 0.49). Among smokers, the estimated ERR of lung cancer per 100 WLM decreased with time since exposure from 3.07 (95% CI -0.04 to 10.32) in the period 5-14 years after exposure to 1.05 (95% CI 0.49 to 1.87) in the period 25+ years after exposure.

CONCLUSIONS

We observed positive associations between cumulative radon exposure and lung cancer, consistent with prior studies. We observed a positive association between cumulative radon exposure and extrathoracic cancers, although the estimates were small. There was evidence that the association between radon and lung cancer was modified by smoking in a multiplicative or super-multiplicative fashion.

Home Radon Testing in Rural Appalachia

PURPOSE

This study compared differences in sociodemographic characteristics, personal risk perception of lung cancer, lung cancer worry, and synergistic risk perception among rural Appalachia residents who completed home radon testing with those who did not, after receiving a free long-term test kit at a rural primary care clinic. The study also examined the association between the Teachable Moment Model constructs and home radon testing.

METHODS

The study was an exploratory correlational design with a convenience sample of (N = 58) adult participants recruited from 2 rural primary care clinics in Appalachia Kentucky. Participants completed a brief survey and were given a free long-term home radon test kit. Multiple logistic regression was used to determine characteristics associated with home radon testing.

FINDINGS

Twenty-eight participants (48%) completed home radon testing. There were no differences in personal risk perception of lung cancer, lung cancer worry, or synergistic risk perception between those who completed home radon testing and those who did not. Age was the only significant factor associated with completion of radon testing (B = 0.077, P = .005). For every 5-year increase in age, participants were 47% more likely to test their home for radon.

CONCLUSION

Providing free home radon test kits in the primary care setting shows promise in prompting radon testing in rural Appalachia. As radon-induced lung cancer risk increases with exposure over time, health care providers in rural Appalachia need to encourage patients of all ages to test their home for radon, especially those who smoke or report smoking in the home.

Indoor Radon Exposure and COPD, Synergic Association? A Multicentric, Hospital-Based Case-Control Study in a Radon-Prone Area

BACKGROUND

COPD is a multifactorial disease which causes considerable mortality and morbidity worldwide. Previous studies assessing the possible relationship between indoor radon exposure and COPD have shown inconclusive results.

METHODS

A multicentric, hospital-based, case-control study was conducted in a Spanish radon-prone area. COPD cases were confirmed by spirometry and controls were selected due to trivial surgery or procedures not related to tobacco consumption. All participants had to have lived for at least 15 years in the same dwelling. Radon measurements were conducted individually in dwellings using alpha-track detectors. Results were obtained using multivariate logistic regression.

RESULTS

189 cases and 747 controls took part. There was no significant association between residential radon concentrations and COPD onset with a OR of 1.12 (95%CI 0.41-3.06) for individuals exposed to more than 200Bq/m³ compared to those exposed to less than 50Bq/m³. Heavy smokers seem to increase their COPD risk if exposed to higher radon concentrations vs those exposed to lower concentrations. There was a statistically significant synergy index between radon exposure and tobacco consumption, S-index 11.60 (95%CI 3.71-36.26). Indoor radon concentration was higher in never/light smokers with COPD compared to controls.

CONCLUSIONS

No association between indoor radon and COPD has been observed. However, there might be some effect modification on the COPD risk in heavy smokers when high radon exposure is present. This is supported by the additive synergy observed. Also, a possible association between indoor radon and COPD onset in never and light smokers needs to be further studied.

A Mixed Methods Population Health Approach to Explore Radon-Induced Lung Cancer Risk Perception in Canada

BACKGROUND

Radon is a predominant indoor air pollutant and second leading cause of lung cancer in radon-prone areas. Despite the gravity of the health risk, residents in Canada have inadequate perception and taken minimal protective actions. Better perception of a risk motivates people to take preventive measures. Scholarship about radon health risk perception is lacking in Canada. We applied a mixed methods population health approach to explore the determinants shaping perception and actions of a resident population in Canada.

METHODS

We conducted mixed surveys (n = 557) and qualitative bilingual interviews (n = 35) with both homeowners and tenants of Ottawa-Gatineau areas. The study explored residents' risk perception and adaptations factors. Descriptive, correlational and regression analyses described and established associations between quantitative variables. Thematic, inductive analyses identified themes in the qualitative data. A mixed methods analysis triangulated both results to draw a holistic perception of the health risk.

RESULTS

Residents' quantitative perceptions of radon health risk, smoking at home, synergistic risk perception, social influence and care for family were associated significantly with their intention to test for radon levels in their home, actual testing and mitigation. These results were explained further with the qualitative findings. Residents who had dual cognitive and emotional awareness of the risk were motivated enough to take preventive actions. Caring for family, knowing others who contracted lung cancer and financial capability were enablers, whereas lack of awareness and homeownership, cost of mitigation and stigma were obstacles to preventive actions. We also explored the dual subjective and objective aspects of risk perception that are influenced by micro- and macro-level determinants.

CONCLUSIONS

Inducing protective action to reduce risk requires comprehensive population-level interventions considering dual perceptions of the risk that can modify the risk determinants. Future research can explore the dual aspects of risk perception and unequal distribution of the risk factors.

Residential radon exposure and hypertensive disorders of pregnancy in Massachusetts, USA: A cohort study

BACKGROUND

Exposure to ionizing radiation has been associated with hypertension, but the relationship between residential radon exposure and hypertensive disorders of pregnancy (HDP) has not been examined.

METHODS

We used the Massachusetts Birth Registry of Vital Records from 2001 to 2015 including women with a singleton pregnancy without prior hypertension. The binary outcome (HDP) included gestational hypertension and pre-eclampsia cases and was assessed using birth certificate data. We obtained 141,665 basement radon measurements from Spruce Environmental Technologies, Inc. and modeled the monthly zip code basement radon level. We used a logistic regression model adjusted for sociodemographic covariates, maternal comorbidities, PM_2.5, season, temperature, and relative humidity. We examined effect modification by maternal age, race, and maternal education as an indicator of socio-economic status.

RESULTS

Of 975,528 women, 3.7% (36,530) of them developed HDP. Zip code level radon ranged from 22 to 333 mBq/m³. An interquartile range (IQR) increase in zip code radon level throughout pregnancy was associated with a 15% increase in the odds of HDP (95% CI 13% to 18%). In women less than 20 years old, an IQR increase in zip code level radon was associated with 38% increase in the odds of HDP (95% CI 24% to 50%), while the effect was smaller in older women. There was no effect modification by maternal race or education.

CONCLUSIONS

In this cohort, higher levels of residential radon are associated with increased odds of HDP. After stratifying by age, this effect was stronger in participants younger than 20 years old. Since the burden of hypertensive disorders of pregnancy is increasing and affects women's future cardiovascular health, identification of modifiable risk factors is of great importance.

Radon Exposure-Therapeutic Effect and Cancer Risk

Largely unnoticed, all life on earth is constantly exposed to low levels of ionizing radiation. Radon, an imperceptible natural occurring radioactive noble gas, contributes as the largest single fraction to radiation exposure from natural sources. For that reason, radon represents a major issue for radiation protection. Nevertheless, radon is also applied for the therapy of inflammatory and degenerative diseases in galleries and spas to many thousand patients a year. In either case, chronic environmental exposure or therapy, the effect of radon on the organism exposed is still under investigation at all levels of interaction. This includes the physical stage of diffusion and energy deposition by radioactive decay of radon and its progeny and the biological stage of initiating and propagating a physiologic response or inducing cancer after chronic exposure. The purpose of this manuscript is to comprehensively review the current knowledge of radon and its progeny on physical background, associated cancer risk and potential therapeutic effects.

Estimating the disease burden of lung cancer attributable to residential radon exposure in Korea during 2006-2015: A socio-economic approach

Estimating the lung cancer disease burden can provide evidence for public health practitioners, researchers, and policymakers. This study uses claim data from lung cancer patients for 2006-2015 from the Korean National Health Insurance Service to estimate the lung cancer burdens attributable to residential radon in Korea using disability-adjusted life years (DALY) and patients' annual economic burden with societal perspectives using the cost-of-illness (COI) method. The number of patients increased during our study period (from 35,866 to 59,168). The disease burden and that attributable to residential radon, respectively, increased from 517.57 to 695.74 and 64.62 (95%; CIs 61.33-67.69) to 86.99 (95%; CIs 82.7-91.1) DALYs per 100,000 patients. The percentage of years lost due to disability among the DALY doubled from 8% to 17%. The cost for all the patients was US$2.33 billion, with US$292 (95%; CIs 278-306) million attributable to residential radon. During the last decade, the lung cancer disease burden increased by 1.34 times, with a doubled percentage of non-fatal burden and average annual growth rate of 9.5% of the total cost. Hence, the burden and cost of lung cancer in Korean provinces have been steadily increasing. The findings could be used as input data for future cost-effectiveness analysis of policies regarding radon reduction.

Miner studies and radiological protection against radon

Fundamental estimates of radon-associated health risk have been provided by epidemiological studies of miners. In total, approximately 15 studies have been conducted worldwide since the 1960s. These results have contributed directly to radiological protection against radon. The present article summarises the main results, with a focus on analyses of miners exposed more recently, estimates of radon lifetime attributable risk, and interaction between radon and smoking. The potential for the upcoming Pooled Uranium Miner Analysis project to further improve our knowledge is discussed.

LUNG CANCER LIFETIME RISKS IN COHORT STUDIES OF URANIUM MINERS

The article summarizes the most recent results from the cohorts of uranium miners, particularly the risks at low exposures and the risk models with modifying effects of exposure rate, age and time since exposure, which are used for the calculation of lifetime risks (LRs). The excess relative risks per unit exposure (ERR/WLM) arising from low exposures were found up to 10 times higher than the crude risk coefficients. For studies that reported models with modifying effect of age, time since exposure and exposure rate, LRs were calculated using the BEIR VI projection. These LRs were also calculated for a model with effect modification on the annual exposure rate. The results were prepared for the UNSCEAR report on 'Lung cancer from exposure to radon.'(1).

Radon Exposure and Neurodegenerative Disease

Background: To carry out a systematic review of scientific literature about the association between radon exposure and neurodegenerative diseases. Methods: We performed a bibliographic search in the following databases: Pub med (Medline), Cochrane, BioMed Central and Web of Science. We collected the data by following a predetermined search strategy in which several terms werecombined. After an initial search, 77 articles were obtained.10 of which fulfilled the inclusion criteria. Five of these 10 studies were related to multiple sclerosis (MS), 2 were about motor neuron diseases (MND), in particular amyotrophic lateral sclerosis (ALS) and 3 were related to both Alzheimer's disease (AD) and Parkinson's disease (PD). Results: The majority of the included articles, suggested a possible association between radon exposure and a subsequent development of neurodegenerative diseases. Some of the studies that obtained statistically significant resultsrevealed a possible association between radon exposure and an increase in MS prevalence. Furthermore, it was also suggested that radon exposure increases MND and AD mortality. Regarding AD and PD, it was observed that certainde cay products of radon-222 (²²²Rn), specifically polonium-210 (²¹⁰Po) and bismuth-210 (²¹⁰Bi), present a characteristic distributionpattern within the brain anatomy. However, the study with the highest scientific evidence included in this review, which investigated a possible association between the concentration of residential radon gas and the MS incidence, revealed no significant results. Conclusions: It cannot be concluded, although it is observed, that there is a possible causal association between radon exposure and neurodegenerative diseases. Most of the available studies are ecological so, studies of higher statistical evidence are needed to establish a causal relationship. Further research is needed on this topic.

A Review of Radon Equilibrium Factors in Underground Mines, Caves, and Thermal Spas

Radon equilibrium factor Feq is an important factor in radon progeny dose assessment. A review of published measurements of Feq shows a range of values from 0.1 to 1.0 reported in studies from more than 26 countries measured in 173 underground mines, and 136 show caves, tourist mines, and thermal spas. The average values of Feq are 0.38 in underground mines and 0.39 for show caves, tourist mines, and thermal spas. The wide range of Feq in those special workplaces suggests that location-, environment-, and operation-specific values are more appropriate than a recommended average value in the calculation of lung bronchial dose. This is especially important in mines or other typically high radon exposure locations because Feq can be used for recording an individual's occupational radon exposure or dose.

Australian action to reduce health risks from radon

In Australia, worker exposure to radon in underground uranium mines has been a focus of policy makers and regulators, and has been well controlled in the industry sector. That cannot be said for public exposure to radon. Radon exposure studies in the late 1980s and early 1990s demonstrated that the levels of radon in Australian homes were some of the lowest in the world. The International Basic Safety Standards, published by the International Atomic Energy Agency, requires the government to establish and implement an action plan for controlling public exposure due to radon indoors. When considering different policy options, it is important to develop radon prevention and mitigation programmes reflecting elements that are unique to the region or country. The Australian Radon Action Plan is being considered at a national level, and presents a long-range strategy designed to reduce radon-induced lung cancer in Australia, as well as the individual risk for people living with high concentrations of radon. In Australia, workers who are not currently designated as occupationally exposed are also considered as members of the public. In the Australian context, there are only a limited set of scenarios that might give rise to sufficiently high radon concentrations that warrant mitigation. These include highly energy efficient buildings in areas of high radon potential, underground workplaces, workplaces with elevated radon concentrations (e.g. spas using natural spring waters), and enclosed workspaces with limited ventilation. The key elements for a successful plan will rely on collaboration between government sectors and other health promotion programmes, cooperative efforts involving technical and communication experts, and partnering with building professionals and other stakeholders involved in the implementation of radon prevention and mitigation.

Lung Cancer in Non-Smokers

Lung cancer is the leading cause of cancer death worldwide and the third most common cancer following breast and prostate.1 As expected, the primary factor leading to lung cancer is tobacco smoke, and as smoking rates have declined, we have also seen an overall decline in lung cancer rates.2 Despite the general reduction in lung cancer rates, the rate of lung cancer in non-smokers has been noted to be increasing.3-8.

Economic valuation of health benefits from using geologic data to communicate radon risk potential

BACKGROUND

Radon exposure is the second leading cause of lung cancer worldwide and represents a major health concern within and outside the United States. Mitigating exposure to radon is especially critical in places with high rates of tobacco smoking (e.g., Kentucky, USA), as radon-induced lung cancer is markedly greater among people exposed to tobacco smoke. Despite homes being a common source of radon exposure, convincing homeowners to test and mitigate for radon remains a challenge. A new communication strategy to increase radon testing among Kentucky homeowners utilizes fine-scale geologic map data to create detailed radon risk potential maps. We assessed the health benefits of this strategy via avoided lung cancer and associated premature mortality and quantified the economic value of these benefits to indicate the potential utility of using geologic map data in radon communication strategies.

METHODS

We estimated the change in radon testing among all 120 counties in Kentucky following a new communication strategy reliant on geologic maps. We approximated the resultant potential change in radon mitigation rates and subsequent expected lung cancer cases and mortality avoided among smokers and non-smokers exposed to 4 pCi/L of radon in the home. We then applied the value of a statistical life to derive the economic value of the expected avoided mortality.

RESULTS

The new communication strategy is estimated to help 75 Kentucky residents in 1 year avoid exposure to harmful radon levels via increased testing and mitigation rates. This equated to the potential avoidance of approximately one premature death due to lung cancer, with a net present value of $3.4 to $8.5 million (2016 USD).

CONCLUSIONS

Our analysis illustrates the potential economic value of health benefits associated with geologic map data used as part of a communication strategy conveying radon risk to the public. Geologic map data are freely available in varying resolutions throughout the United States, suggesting Kentucky's radon communication strategy using geologic maps can be employed in other states to educate the public about radon. As this is only a single application, in a single state, the economic and health benefits of geologic map data in educating the public about radon are likely to exceed our estimates.

PUMA - pooled uranium miners analysis: cohort profile

OBJECTIVES

Epidemiological studies of underground miners have provided clear evidence that inhalation of radon decay products causes lung cancer. Moreover, these studies have served as a quantitative basis for estimation of radon-associated excess lung cancer risk. However, questions remain regarding the effects of exposure to the low levels of radon decay products typically encountered in contemporary occupational and environmental settings on the risk of lung cancer and other diseases, and on the modifiers of these associations. These issues are of central importance for estimation of risks associated with residential and occupational radon exposures.

METHODS

The Pooled Uranium Miner Analysis (PUMA) assembles information on cohorts of uranium miners in North America and Europe. Data available include individual annual estimates of exposure to radon decay products, demographic and employment history information on each worker and information on vital status, date of death and cause of death. Some, but not all, cohorts also have individual information on cigarette smoking, external gamma radiation exposure and non-radiological occupational exposures.

RESULTS

The PUMA study represents the largest study of uranium miners conducted to date, encompassing 124 507 miners, 4.51 million person-years at risk and 54 462 deaths, including 7825 deaths due to lung cancer. Planned research topics include analyses of associations between radon exposure and mortality due to lung cancer, cancers other than lung, non-malignant disease, modifiers of these associations and characterisation of overall relative mortality excesses and lifetime risks.

CONCLUSION

PUMA provides opportunities to evaluate new research questions and to conduct analyses to assess potential health risks associated with uranium mining that have greater statistical power than can be achieved with any single cohort.