A combined analysis of North American case-control studies of residential radon and lung cancer

Radon and lung cancer: Current status and future prospects

Beyond tobacco smoking, radon takes its place as the second most significant contributor to lung cancer, excluding hereditary and other biologically related factors. Radon and its byproducts play a pivotal role in exposing humans to elevated levels of natural radiation. Approximately 10-20 % of lung cancer cases worldwide can be attributed to radon exposure, leading to between 3 % and 20 % of all lung cancer-related deaths. Nevertheless, a knowledge gap persists regarding the association between radon and lung cancer, impeding radon risk reduction initiatives globally. This review presents a comprehensive overview of the current state of research in epidemiology, cell biology, dosimetry, and risk modeling concerning radon exposure and its relevance to lung cancer. It also delves into methods for measuring radon concentrations, monitoring radon risk zones, and identifying priorities for future research.

Adjuvant Novel Nanocarrier-Based Targeted Therapy for Lung Cancer

Lung cancer has the lowest survival rate due to its late-stage diagnosis, poor prognosis, and intra-tumoral heterogeneity. These factors decrease the effectiveness of treatment. They release chemokines and cytokines from the tumor microenvironment (TME). To improve the effectiveness of treatment, researchers emphasize personalized adjuvant therapies along with conventional ones. Targeted chemotherapeutic drug delivery systems and specific pathway-blocking agents using nanocarriers are a few of them. This study explored the nanocarrier roles and strategies to improve the treatment profile's effectiveness by striving for TME. A biofunctionalized nanocarrier stimulates biosystem interaction, cellular uptake, immune system escape, and vascular changes for penetration into the TME. Inorganic metal compounds scavenge reactive oxygen species (ROS) through their photothermal effect. Stroma, hypoxia, pH, and immunity-modulating agents conjugated or modified nanocarriers co-administered with pathway-blocking or condition-modulating agents can regulate extracellular matrix (ECM), Cancer-associated fibroblasts (CAF),Tyro3, Axl, and Mertk receptors (TAM) regulation, regulatory T-cell (Treg) inhibition, and myeloid-derived suppressor cells (MDSC) inhibition. Again, biomimetic conjugation or the surface modification of nanocarriers using ligands can enhance active targeting efficacy by bypassing the TME. A carrier system with biofunctionalized inorganic metal compounds and organic compound complex-loaded drugs is convenient for NSCLC-targeted therapy.

Lung cancer in patients who have never smoked - an emerging disease

Lung cancer is the most common cause of cancer-related deaths globally. Although smoking-related lung cancers continue to account for the majority of diagnoses, smoking rates have been decreasing for several decades. Lung cancer in individuals who have never smoked (LCINS) is estimated to be the fifth most common cause of cancer-related deaths worldwide in 2023, preferentially occurring in women and Asian populations. As smoking rates continue to decline, understanding the aetiology and features of this disease, which necessitate unique diagnostic and treatment paradigms, will be imperative. New data have provided important insights into the molecular and genomic characteristics of LCINS, which are distinct from those of smoking-associated lung cancers and directly affect treatment decisions and outcomes. Herein, we review the emerging data regarding the aetiology and features of LCINS, particularly the genetic and environmental underpinnings of this disease as well as their implications for treatment. In addition, we outline the unique diagnostic and therapeutic paradigms of LCINS and discuss future directions in identifying individuals at high risk of this disease for potential screening efforts.

Immune status of people living in the Tande-Tande sub-village (Indonesia), an area with high indoor radon concentration

On Earth, there are significant variations in terms of exposure to naturally occurring radiation among different areas. Radon, a naturally-occurring radioactive gas that is the primary cause of lung cancer in nonsmokers and the second most prevalent cause among smokers, poses a considerable risk. Indoor radon, in particular, constitutes the most substantial source of natural radiation to which individuals are exposed. This study assessed the immune status of a population chronically exposed to high indoor radon concentration in Indonesia. Fifty-seven subjects from the Tande-Tande sub-village (high indoor radon concentration area) were compared to fifty-three participants living in the Topoyo village (low concentration area). We contrasted the immunological conditions of these two populations by measuring levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-4 (IL-4), and IL-10 in serum. Moreover, we also measured levels of the nuclear factor kappa B (NF-κB), superoxide dismutase (SOD), glutathione peroxidase (GPX), and protein kinase B in its phosphorylated (pAkt) and non-phosphorylated form (Akt) in peripheral blood mononuclear cells (PBMCs) of a subset of participants (31 from each population). TNF-α, IFN-γ, and IL-4 levels in Tande-Tande sub-village inhabitants were significantly lower than those in the control group living in the Topoyo village (p = 0.001, p = 0.017, and p = 0.002). The concentration of IL-10 also tended to be lower in people living in the high indoor radon concentration area, but it did not differ significantly between Tande-Tande sub-village inhabitants and Topoyo inhabitants (p = 0.106). Protein levels of NF-κB, pAkt, and Akt in Tande-Tande sub-village inhabitants also did not differ significantly between Tande-Tande sub-village inhabitants and Topoyo inhabitants (p = 0.234, p = 0.210, and p = 0.657). Similarly, activities of SOD and GPX did not differ significantly between the two populations (p = 0.569 and p = 0.949). Overall, despite their chronic exposure to high indoor radon concentrations, our study revealed no increase in the levels of TNF-α, IFN-γ, IL-10, IL-4, SOD, and GPX in the inhabitants of Tande-Tande sub-village compared with people living in the Topoyo village. Furthermore, our study demonstrated no activation in the Akt pathway, as indicated by the pAkt/Akt ratio observed in PBMC lysates of individuals residing in the Tande-Tande sub-village.

Analysis of the cancer occurrence related to natural radioactivity in the Rio Grande do Norte State, Brazil

The state of Rio Grande do Norte, located in the Northeast region of Brazil, has areas of granites and pegmatites with minerals that have varying concentrations of uranium. Consequently, high concentrations of radon gas, a carcinogenic substance for humans, can occur. The present study aimed to assess the occurrence of cancer and its association with exposure to sources of natural radioactivity using geological and geophysical information in the aforementioned state. The spatial dependence of pulmonary, breast, stomach, leukemia, and skin cancer cases with the location of radioisotope sources were analyzed using geoprocessing tools. The geoprocessing analysis showed a differential pattern of uranium emission throughout the state, with the highest emission from areas with pegmatites outcrops. A spatial dependency of cancer cases was shown (Moran index: 0.43; p < 0.01). Moreover, a higher rate of natural radioactivity-cancer cases was associated with the high-intensity natural radioactivity areas: odds ratio:1.21 (95% CI 1.20; 1.23), following the same pattern when separately compared the different related types of cancer. These results highlight the importance of natural radioactivity as a public health problem in the Brazilian environmental scenario, confirming the need for further studies as the first toward understanding and implementing health management strategies mitigating the exposures, especially in areas of environmental risk.

Radon progeny measurements in a ventilated filter system to study respiratory-supported exposure

Radon (222Rn) and its progeny are responsible for half of the annual dose from natural radiation and the most frequent cause for lung cancer induction after smoking. During inhalation, progeny nuclides accumulate in the respiratory tract while most of the radon gas is exhaled. The decay of progeny nuclides in the lung together with the high radiosensitivity of this tissue lead to equivalent doses implying a significant cancer risk. Here, we use gamma spectroscopy to measure the attachment of radon progeny on an air-ventilated filter system within a radon enriched atmosphere, mimicking the respiratory tract. A mathematical model was developed to describe the measured time-dependent activities of radon progeny on the filter system. We verified a linear relation between the ambient radon activity concentration during exposure and the amount of decay products on the filter system. The measured activities on the filters and its mathematical description are in good agreement. The developed experimental set-up can thus serve to further investigate the deposition of radon progeny in the respiratory tract under varying conditions for determination of dose conversion factors in radiation protection, which we demonstrate by deriving dose estimations in mouse lung.

Evaluation of radon hazards at the rural settlements of Uzbekistan

The "passive" sorption detectors based on the activated charcoal together with scintillation spectrometry were utilized to measure radon flux density from the soil surface as well as volumetric activity of indoor radon at the dwellings of rural areas of Uzbekistan. Additionally, gamma dose rates as well as concentrations of natural radionuclides in soil and building materials samples were determined. Based on the values of natural radionuclides, common radiological indices have been calculated. It was found that varying greatly, 94% radon flux density values did not exceed 80 mBq/(m²·s), while volumetric activities of radon were in the range of 35-564 Bq/m³. The radium equivalent activity for studied soil and building materials samples were below the allowed limit of 370 Bq/kg. Computed gamma dose rates were in the range of 55.50-73.89 ƞGyh^-1 below the limit of 80 ƞGyh^-1 and annual effective dose rate 0.068-0.091 mSvy^-1, the average value of which was higher than the standard limit > 0.47 mSvy^-1. The gamma representative index range was 0.89-1.19 with an average of 1.002 which was higher than the standard limit of 1.0. The range of activity utilization index was equal to 0.70-0.86 with an average value 0.77 which was lower than the recommended level ≤ 2.0. And lastly, excess lifetime cancer risk index values were from 1.9 × 10^-4 to 2.5 × 10^-4 and were lower than the recommended value 2.9 × 10^-4 indicating low radiological risk. The results are consistent with the research conducted by other authors earlier, implying suitability of employing the method for the assessment of residential areas.

Geologic, seasonal, and atmospheric predictors of indoor home radon values

Exposure to tobacco smoke and radon cause lung cancer. Radioactive decay of naturally occurring uranium in bedrock produces radon. Seasonality, bedrock type, age of home, and topography have been associated with indoor radon, but the research is mixed. The study objective was to examine the relationships of geologic (soil radon and bedrock) and seasonal (warm and cold times of the year) factors with indoor home radon values in citizen scientists' homes over time, controlling for atmospheric conditions, topography, age of home, and home exposure to tobacco smoke. We collected and analyzed indoor radon values, soil radon gas concentrations, and dwelling- and county-level geologic and atmospheric conditions on 66 properties in four rural counties during two seasons: (1) summer 2021 (n = 53); and (2) winter/spring 2022 (n = 52). Citizen scientists measured indoor radon using Airthings radon sensors, and outdoor temperature and rainfall. Geologists obtained soil radon measurements using RAD7 instruments at two locations (near the dwelling and farther away) at each dwelling, testing for associations of indoor radon values with soil values, bedrock type, topography, and atmospheric conditions. Bedrock type, near soil radon levels, home age, and barometric pressure were associated with indoor radon. Dwellings built on carbonate bedrock had indoor radon values that were 2.8 pCi/L (103.6 Bq m-3) higher, on average, compared to homes built on siliclastic rock. Homes with higher near soil radon and those built <40 ago were more likely to have indoor radon ⩾4.0 pCi/L (148 Bq m-3). With higher atmospheric barometric pressure during testing, observed indoor radon values were lower. Seasonality and topography were not associated with indoor radon level. Understanding relationships among bedrock type, soil radon, and indoor radon exposure allows the development of practical predictive models that may support pre-construction forecasting of indoor radon potential based on geologic factors.

The Efficacy of Immunotherapy in Long-Term Survival in Non-Small Cell Lung Cancer (NSCLC) Associated with the Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

INTRODUCTION

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of hyponatremia in cancer patients, occurring most frequently in patients with small cell lung cancer. However, this syndrome occurs extremely rarely in patients with non-small cell lung cancer. The results of the clinical trials have revealed that immuno-oncological therapies are effective for long periods of time, providing hope for long survival and with a good quality of life.

CASE PRESENTATION

We present the case of a female patient who was 62 years old at the time of diagnosis in 2016 who underwent surgery for a right pulmonary tumor (pulmonary adenocarcinoma) and subsequently underwent adjuvant chemotherapy. The patient had a left inoperable mediastinohilar relapse in 2018, which was treated using polychemotherapy The patient also had an occurrence of progressive metastasis and a syndrome of inappropriate antidiuretic hormone secretion (SIADH) in 2019 for which immunotherapy was initiated. The patient has continued with immunotherapy until the time this study began to be written (April 2023), the results being the remission of hyponatremia, the clinical benefits and long-term survival.

DISCUSSION

The main therapeutic option for SIADH in cancer patients is the treatment of the underlying disease, and its correction depends almost exclusively on a good response to oncological therapy. The initiation of immunotherapy at the time of severe hyponatremia occurrence led to its remission as well as the remission of the other two episodes of hyponatremia, which the patient presented throughout the evolution of the disease, demonstrating an obvious causal relationship between SIADH and the favorable response to immunotherapy.

CONCLUSIONS

Each patient must be approached individually, taking into account the various particular aspects. Immunotherapy proves to be the innovative treatment that contributes to increasing the survival of patients with metastatic non-small cell lung cancer and to increasing their quality of life.

Parametrization identification and characterization of the radon priority areas for indoor radon risk management

The aim of work is to contribute to the development of methodologies concerning the selection and characterisation of radon priority areas. The selection of areas was based on risk from indoor radon exposure, expressed in terms of number of expected deaths per year. Radon data come from a survey carried out in the Lazio Region (Italy) and consist of 5297 indoor concentration measurements. Population data were also used. Data showed that dwellings with concentrations above 300 Bq/m³, taken as reference level (RL), are not confined to specific areas, but rather spread out over the territory. An absolute risk model has been chosen to predict annual deaths on a regular grid of cells 2kmx2km sized. The analysis showed that 21.7% of the territory is completely uninhabited and that another 13.9% presents a marginal risk, quantifiable in total as less than one expected death per year. The remaining territory is of interest to identify the areas where dwellings with a concentration higher than the RL would be located. It was found that: such dwellings occur with different percentage in all the cells; exposed people varies from a few to almost 2000 per cell; indoor radon risk from exposure above RL is dominated by the number of exposed people and amounts to 106 deaths per year; the number of cells where a such risk is low is far greater than where the risk is high. These findings led to restrict RPA to the smallest set of cells that retained 85% of risk, i.e. 90 expected deaths per year. This percentage has been subjectively set because the technical and economic information required for its optimal calculation was not available. Based on this assumption, the RPA were identified by applying a threshold of 43 to the number of exposed people in each cell, in order to reach 85% of risk. The other main characteristics, also expressed as percentages of the corresponding totals within the area of interest, were found to be: extension 31.5% and exposed people 84%.

Experimental Setups for In Vitro Studies on Radon Exposure in Mammalian Cells-A Critical Overview

Naturally occurring radon and its short lived progeny are the second leading cause of lung cancer after smoking, and the main risk factor for non-smokers. The radon progeny, mainly Polonium-218 (²¹⁸Po) and Polonium-214 (²¹⁴Po), are responsible for the highest dose deposition in the bronchial epithelium via alpha-decay. These alpha-particles release a large amount of energy over a short penetration range, which results in severe and complex DNA damage. In order to unravel the underlying biological mechanisms which are triggered by this complex DNA damage and eventually give rise to carcinogenesis, in vitro radiobiology experiments on mammalian cells have been performed using radon exposure setups, or radon analogues, which mimic alpha-particle exposure. This review provides an overview of the different experimental setups, which have been developed and used over the past decades for in vitro radon experiments. In order to guarantee reliable results, the design and dosimetry of these setups require careful consideration, which will be emphasized in this work. Results of these in vitro experiments, particularly on bronchial epithelial cells, can provide valuable information on biomarkers, which can assist to identify exposures, as well as to study the effects of localized high dose depositions and the heterogeneous dose distribution of radon.

Regulation of Autophagy via Carbohydrate and Lipid Metabolism in Cancer

Metabolic changes are an important component of tumor cell progression. Tumor cells adapt to environmental stresses via changes to carbohydrate and lipid metabolism. Autophagy, a physiological process in mammalian cells that digests damaged organelles and misfolded proteins via lysosomal degradation, is closely associated with metabolism in mammalian cells, acting as a meter of cellular ATP levels. In this review, we discuss the changes in glycolytic and lipid biosynthetic pathways in mammalian cells and their impact on carcinogenesis via the autophagy pathway. In addition, we discuss the impact of these metabolic pathways on autophagy in lung cancer.

Indoor Radon Concentration Levels in Healthcare Settings: The Results of an Environmental Monitoring in a Large Italian University Hospital

The aim of the study is to determine the radon concentrations in the University Hospital of Bari, Apulia Region, Southern Italy. The monitoring took place from 2017 to 2018 for a total of 402 days and included 3492 premises. Radon environmental sampling was performed with passive dosimeters of the CR-39 type. The highest mean concentration was found in basement rooms (118.9 Bq/m³), followed by ground-floor rooms (88.2 Bq/m³), first-floor rooms (78.1 Bq/m³), second-floor rooms (66.7 Bq/m³), and third-floor rooms (68.9 Bq/m³). An average radon concentration lower than the WHO recommended level of 100 Bq/m³ was detected in 73.5% of monitored environments, while only 0.9% exceeded the reference level of 300 Bq/m³ set by the national law (Legislative Decree 101/2020). The frequency of environments in which radon concentrations exceed 300 Bq/m³ is significantly higher in the basement (p-value < 0.001). As for a previous preliminary investigation in the same hospital conducted on a much smaller number of premises (n = 401), most of the monitored environments had radon concentrations lower than the reference levels set by the new national law, and the risk to the healthcare workers' health derived from occupational exposure to radon could be considered acceptable.

Lung cancer incidence attributable to residential radon exposure in Finland

This study aimed to estimate (1) the number of avoidable lung cancer cases attributable to residential radon in Finland in 2017, separately by age, sex, dwelling type and smoking status, (2) the impact of residential radon alone and the joint effect of residential radon and smoking on the number of lung cancers and (3) the potential decrease in the number of radon-attributable lung cancers if radon concentrations exceeding specified action levels (100, 200 and 300 Bq m^-3) would have been mitigated to those levels. Population-based surveys of radon concentrations and smoking patterns were used. Observed radon levels were contrasted with 25 Bq m^-3 representing a realistic minimum level of exposure. Lung cancer risk estimates for radon and smoking were derived from literature. Lastly, the uncertainty due to the estimation of exposure and risk was quantified using a computationally derived uncertainty interval. At least 3% and at most 8% of all lung cancers were estimated as being attributable to residential radon. For small cell carcinoma, the proportion of cases attributable to radon was 8-13%. Among smokers, the majority of the radon-related cases were attributable to the joint effect of radon and smoking. Reduction of radon exposure to 100 Bq m^-3 action level would eliminate approximately 30% of radon-attributable cases. Estimates were low compared with the literature, given the (relatively high) radon levels in Finland. This was mainly due to the lower radon levels and higher smoking prevalence in flats than in houses and a more realistic point of comparison, factors which have been ignored in previous studies. The results can guide actions in radon protection and in prevention of lung cancers.

A case study on seasonal and annual average indoor radon, thoron, and their progeny level in Kohima district, Nagaland, India

Indoor radon and thoron survey has been carried out in 50 dwellings under Kohima district, Nagaland, India, using the latest measurement technology. The survey has been carried out for a one-year period in 3 different seasons, and the dwellings were selected according to the building materials used for construction. Indoor radon and thoron concentrations, as well as their progeny, followed a predictable pattern with greater levels in the winter and lower levels in the summer. Concrete housing had greater radon and thoron concentrations than bamboo and semi-wood/bamboo homes. The equilibrium factor (E.F.) and inhalation dose due to radon, thoron, and their corresponding progeny were also studied in the present study.

Indoor radon survey in Whitehorse, Canada, and dose assessment

Radon-222 (²²²Rn) and its decay products are the primary sources of a population's exposure to background ionizing radiation. Radon decay products are the leading cause of lung cancer for non-smokers and the second leading cause of lung cancer after smoking for smokers. A community-driven long-term radon survey was completed in 232 residential homes in different subdivisions of Whitehorse, the capital of the Yukon, during the heating season from November to April in 2016-2017 and in 2017-2018. Radon concentrations were measured in living rooms and bedrooms on ground floors. The arithmetic and geometric means of indoor radon activity concentrations in different subdivisions of Whitehorse ranged from 52 ± 0.6 Bq m^-3and 37 ± 2.3 Bq m^-3in the Downtown area of Whitehorse to 993.0 ± 55.0 Bq m^-3and 726.2 ± 2.4 Bq m^-3in Wolf Creek. Underlying geology and glacial surfaces may partly explain these variations of indoor radon concentrations in subdivisions of Whitehorse. A total of 78 homes (34.0%) had radon concentrations higher than 100 Bq m^-3, 47 homes (20.5%) had concentrations higher than 200 Bq m^-3and 33 homes (14.4%) had concentrations higher than 300 Bq m^-3. The indoor radon contribution to the annual effective inhalation dose to residents ranged from 3.0 mSv in the Downtown area to 51.0 mSv in Wolf Creek. The estimated annual average dose to adults in Whitehorse, Yukon, is higher than the world's average annual effective dose of 1.3 mSv due to the inhalation of indoor radon. The annual radon inhalation effective dose was assessed using radon measurements taken during winter; hence the assessed dose may be overestimated. Cost-efficient mitigation methods are available to reduce radon in existing buildings and to prevent radon entry into new buildings.

Exposure to radon and heavy particulate pollution and incidence of brain tumors

BACKGROUND

Global incidence for brain tumors varies substantially without explanation. Studies correlating radon exposure and incidence are inconclusive. Particulate pollution has been linked to increased tumor incidence. Particulates may disrupt the blood-brain barrier allowing intracranial exposure to oncogenic radon. We investigated the relationship between exposure to residential radon, particulate pollution, and brain tumor incidence in the United States (US).

METHODS

County-level median radon testing results and annual air quality index values were obtained and divided into tertiles. Counties without both values were excluded. Four groups of counties were generated: high particulate/high radon (high/high), high/low, low/high, and low/low. Using incidence data from the Central Brain Tumor Registry of the US (provided by CDC's National Program of Cancer Registries and NCI's SEER), annual age-adjusted incidence rates (AAAIRs) by group were generated by behavior. Incidence rate ratios were calculated to examine for significant differences (α = .05). Poisson regression accounting for possible confounders was conducted.

RESULTS

Counties with available data included 83% of the US population. High/high exposure was significantly associated with increased AAAIR of all non-malignant tumors (up to 26% higher, including most meningiomas) even after accounting for potential confounders. An increased AAAIR was noted for all malignant tumors (up to 10% higher), including glioblastoma, but was negated after accounting for demographic/socioeconomic differences.

CONCLUSIONS

We present the first report suggesting increased non-malignant brain tumor incidence in regions with high particulate and radon exposure. These findings provide insight into unexplained variation in tumor incidence. Future studies are needed to validate these findings in other populations.

Indoor radon survey in Greenland and dose assessment

Indoor radon and its decay products are the primary sources of the population's exposure to background ionizing radiation. Radon decay products are one of the leading causes of lung cancer, with a higher lung cancer risk for smokers due to the synergistic effects of radon decay products and cigarette smoking. A total of 459 year-long radon measurements in 257 detached and semi-detached residential homes in southwest and south Greenland were carried out, and a dose assessment for adults was performed. The annual arithmetic and geometric means of indoor radon concentrations was 10.5 ± 0.2 Bq m^-3 and 8.0 ± 2.3 Bq m^-3 in Nuuk, 139.0 ± 1.0 Bq m^-3 and 97.3 ± 2.1 Bq m^-3 in Narsaq, and 42.1 ± 0.7 Bq m^-3 and 22.0 ± 3.1 Bq m^-3 in Qaqortoq. Arithmetic and geometric mean radon concentration of 79.0 Bq m^-3 and 50.3 Bq m^-3 were estimated for adult, person-weighted living in south Greenland. The total number of detached and semi-detached residential homes where indoor radon is exceeding 100 Bq m^-3, 200 Bq m^-3, and 300 Bq m^-3 is 37 homes (15.0%), 13 homes (5.2%), and 8 homes (3.2%), respectively. A positive correlation between indoor air radon concentrations and underlying geology was observed. The indoor radon contribution to the annual inhalation effective dose to an average adult was 0.5 mSv in Nuuk, 6.5 mSv in Narsaq, 2.0 mSv in Qaqortoq, and 4.0 mSv for south Greenland adult person weighted. The estimated annual average effective dose to adults in Narsaq is higher than the world's average annual effective dose of 1.3 mSv due to inhalation of indoor radon. Cost-efficient mitigation methods exist to reduce radon in existing buildings, and to prevent radon entry into new buildings.

Patterns of indoor radon concentrations, radon-hazard potential, and radon testing on a small geographic scale in Utah

INTRODUCTION

Currently, there are no publicly-available estimates of indoor radon concentration at scales smaller than the county. Radon-hazard potential soil maps that reflect underlying geologic factors can be created at small geographic scale and linked to residential and census data. We determined the association between residential radon tests and high radon-hazard potential soil at the residential and block group levels using a large Utah-based dataset. We also identified characteristics of block groups with limited tests in the dataset.

METHODS

We geocoded a dataset of residential radon tests obtained from 2001 to 2017 by a statewide educational program. We linked each location to maps of radon-hazard potential soil, the Environmental Protection Agency's (EPA) county radon zones. We also calculated the number of tests conducted in each block group and linked block groups to demographic data from the 2020 United States census. Log-linear and logistic models identified the association between residential home test results and 1) radon-hazard potential soil of each residence, 2) percent of residences on high radon-hazard potential soils in block groups, and 3) EPA's radon zones. We compared demographic characteristics among block groups with ≥5 or <5 residential tests in our dataset.

RESULTS

Approximately 42% of homes in the dataset tested ≥4 pCi/L. We found significant positive associations for residential radon test results with 1) residential location on high radon-hazard potential soil and 2) block groups with >0% of residences on high radon-hazard potential soil. EPA radon zones were not associated with residential test results. Block groups with <5 tests had higher than the statewide median percentage of Hispanic residents (OR = 2.46, 95% CI = 1.89-3.21) and were located in rural counties.

DISCUSSION

Radon-hazard potential soil has a significant association with residential home radon tests. More efforts are needed to improve radon testing in block groups that are rural and have greater percentages of racial minorities.

Effects of spatial variation in dose delivery: what can we learn from radon-related lung cancer studies?

Exposure to radon progeny results in heterogeneous dose distributions in many different spatial scales. The aim of this review is to provide an overview on the state of the art in epidemiology, clinical observations, cell biology, dosimetry, and modelling related to radon exposure and its association with lung cancer, along with priorities for future research. Particular attention is paid on the effects of spatial variation in dose delivery within the organs, a factor not considered in radiation protection. It is concluded that a multidisciplinary approach is required to improve risk assessment and mechanistic understanding of carcinogenesis related to radon exposure. To achieve these goals, important steps would be to clarify whether radon can cause other diseases than lung cancer, and to investigate radon-related health risks in children or persons at young ages. Also, a better understanding of the combined effects of radon and smoking is needed, which can be achieved by integrating epidemiological, clinical, pathological, and molecular oncology data to obtain a radon-associated signature. While in vitro models derived from primary human bronchial epithelial cells can help to identify new and corroborate existing biomarkers, they also allow to study the effects of heterogeneous dose distributions including the effects of locally high doses. These novel approaches can provide valuable input and validation data for mathematical models for risk assessment. These models can be applied to quantitatively translate the knowledge obtained from radon exposure to other exposures resulting in heterogeneous dose distributions within an organ to support radiation protection in general.

Molecular Characteristics of Radon Associated Lung Cancer Highlights MET Alterations

Simple Summary

Lung cancer (LC) is the leading cause of cancer death worldwide. After smoking, one of the most prominent risk factors for LC development is radon (Rn) exposure. In our study we analysed and compared the genetic landscape of LC patients from a Rn exposed village with local matched non-exposed patients. Within the concordant genetic landscape, an increase in genetic MET proto-oncogene, receptor tyrosine kinase (MET) alteration in the Rn-exposed cohort was monitored, underlining the importance of routine MET testing and potential to enable a more effective treatment for this specific subgroup.

Abstract

Effective targeted treatment strategies resulted from molecular profiling of lung cancer with distinct prevalent mutation profiles in smokers and non-smokers. Although Rn is the second most important risk factor, data for Rn-dependent driver events are limited. Therefore, a Rn-exposed cohort of lung cancer patients was screened for oncogenic drivers and their survival and genetic profiles were compared with data of the average regional population. Genetic alterations were analysed in 20 Rn-exposed and 22 histologically matched non-Rn exposed LC patients using targeted Next generation sequencing (NGS) and Fluorescence In Situ Hybridization (FISH). Sufficient material and sample quality could be obtained in 14/27 non-exposed versus 17/22 Rn-exposed LC samples. Survival was analysed in comparison to a histologically and stage-matched regional non-exposed lung cancer cohort (n = 51) for hypothesis generating. Median overall survivals were 83.02 months in the Rn-exposed and 38.7 months in the non-exposed lung cancer cohort (p = 0.22). Genetic alterations of both patient cohorts were in high concordance, except for an increase in MET alterations and a decrease in TP53 mutations in the Rn-exposed patients in this small hypothesis generating study.

Mapping the Way to Good Health: The Interdisciplinary Challenges of Geographers in Medical Research

Geography has an important role to play in shaping the direction of medical research. In particular, its tools and theory provide essential understanding to the impacts of place on health behaviors and outcomes. Understanding some of its evolution-particularly into the subfield of medical geography-is therefore useful both for geographers and medical researchers. In this paper, we present some of the debates that geographers have grappled with, the growth of GIS (particularly in the context of medical research), some important methodological considerations that geographers help center, and some recommendations for future work at this nexus. Throughout, we speak from the perspective of geographers who have worked nearly exclusively in the health sciences since obtaining our PhDs.

Association between Air Pollution and Squamous Cell Lung Cancer in South-Eastern Poland

Air pollution is closely associated with the development of respiratory illness. The aim of the present study was to assess the relationship between long-term exposure to PM2.5, PM10, NO₂, and SO₂ pollution and the incidence of lung cancer in the squamous subtype in south-eastern Poland from the years 2004 to 2014. We collected data of 4237 patients with squamous cell lung cancer and the level of selected pollutants. To investigate the relationship between the level of concentrations of pollutants and the place of residence of patients with lung cancer in the squamous subtype, proprietary pollution maps were applied to the places of residence of patients. To analyze the data, the risk ratio was used as well as a number of statistical methods, i.e., the pollution model, inverse distance weighted interpolation, PCA, and ordered response model. Cancer in women and in men seems to depend in particular on the simultaneous inhalation of NO₂ and PM10 (variable NO₂PM10) and of NO₂ and SO₂ (variable NO₂ SO₂), respectively. Nitrogen dioxide exercises a synergistic leading effect, which once composed with the other elements it becomes more persistent in explaining higher odds in the appearance of cancers and could constitute the main cause of squamous cancer.

Groundwater radon exposure and risk of lung cancer: A population-based study in Finland

Naturally occurring radioactive elements can be found in groundwater and exposure to such elements is associated with an increased risk of lung cancer. In this study, we aimed to observe the association between exposure to these radioactive elements in groundwater and the risk of lung cancer in selected regions in Finland. This is a population-based study from 1955 to 2019 in Finland. The exposed municipalities with their corresponding hospital districts were selected based on radon measurements at groundwater treatment plants. Lung cancer cases were obtained from the Finnish cancer registry. The 5-year incidence rates for lung cancer were calculated and a comparison was made between each of the hospital districts with radon exposure. More than 93,000 cases of lung cancer were reported in the radon-exposed regions over the examined period of 64 years. The highest number of cases was recorded in the Helsinki University hospital district and the least in the Southern Savo hospital district. Similarly, the lung cancer incidence rate was highest in Lapland and lowest in the Southern Savo hospital district. The number of daily smokers in the working-age population appears to have decreased in all the hospital districts from 2013 to 2018. A statistically significant increased risk of lung cancer was observed in the high radon-exposed hospital districts compared to those with lower exposure. Groundwater radon exposure is observed to be associated with an increased risk of lung cancer.

A COMPREHENSIVE STUDY ON INDOOR RADON, THORON AND THEIR PROGENY LEVEL IN DIMAPUR DISTRICT OF NAGALAND, INDIA

Indoor radon (222Rn), thoron (220Rn) and their progeny concentrations were detected in several homes in Dimapur district, Nagaland, utilizing Direct Radon and Thoron progeny sensors based on solid-state Nuclear Track Detectors (Type-2 film) and pinhole type radon-thoron discriminating dosemeters. For three separate seasons, the annual inhalation dose has been determined in 80 residences in the research regions. The residences were chosen to have various types of housing, such as concrete, semi-wood/bamboo and bamboo, with varying levels of ventilation that contribute to indoor 222Rn, 220Rn and their progeny. The inhalation dose in the survey area lies between 0.33 and 3.04 mSvy-1 and is within the reference value as suggested by ICRP, 2018.

Chromosome aberrations, micronucleus frequency, and catalase concentration in a population chronically exposed to high levels of radon

PURPOSE

To deepen our knowledge on the effects of high levels of indoor radon exposure, we assessed the frequencies of unstable and stable chromosome aberrations and micronucleus (MN), as well as the concentration of an endogenous antioxidant (catalase, CAT), in blood samples of individuals chronically exposed to high indoor radon concentrations in Indonesia (Tande-Tande sub-village, Mamuju, West Sulawesi). Moreover, we also investigated the occurrence of a radio-adaptive response (RAR) in Tande-Tande sub-village inhabitants using the G2 MN assay.

MATERIALS AND METHODS

The frequencies of dicentric (DC), acentric (AF), ring (R), and translocation (Tr) chromosomes in Tande-Tande inhabitants were compared to those in people living in a reference area with low levels of indoor radon levels (Topoyo village, Indonesia). The number of MN per 1000 binucleated cells (BNC) and CAT concentration per total protein was quantified and compared between groups. Lastly, we irradiated (2 Gy) phytohemagglutinin-stimulated samples in vitro and measured the frequency of MN to verify the occurrence of a RAR in Tande-Tande sub-village inhabitants.

RESULTS AND CONCLUSION

The frequencies of DC, AF, and Tr did not differ between Tande-Tande inhabitants and control subjects (p = 0.350, 0.521, 0.597). The frequency of MN in Tande-Tande inhabitants was significantly lower than that in the control group (p = 0.006). Similarly, CAT concentration in Tande-Tande inhabitants was also significantly lower than that in the control population (p < 0.001). Significant negative correlations were identified for MN number and CAT concentration versus indoor radon concentration, annual effective dose, or cumulative dose both within groups and when all data were analyzed together. Our findings indicate that, despite the high indoor radon levels, Tande-Tande inhabitants are not under oxidative stress, since this group had lower CAT concentration and MN frequency than those in the control group. The negative correlation between MN frequency and indoor radon concentration, annual effective dose, and cumulative dose suggests the occurrence of an RAR phenomenon in Tande-Tande sub-village inhabitants. This interpretation is also supported by the results of the G2 MN assay, which revealed lower MN frequencies after in vitro irradiation of samples from Tande-Tande sub-village inhabitants than those in samples from the control group (p = 0.0069, for cumulative MN frequency; p = 0.0146, for radiation-induced MN only).

Interaction between occupational radon exposure and tobacco smoke: a systematic review

INTRODUCTION

: The risk of lung cancer from radon exposure was small compared to tobacco smoking (BEIR VI), but the relationship between these two carcinogenic agents has yet to be quantitatively estimated. The objective of this systematic review was to evaluate the last evidences on the role of radon occupational exposures and tobacco smoke on lung cancer risk.

AREAS COVERED

: Thirteen articles were selected using two different databases, PubMed and Scifinder, and were limited to those published from 2010 to 2021. The reference list of selected studies was reviewed to identify other relevant papers.

EXPERT OPINION

: Seven papers included in this systematic review did not deal with the multiplicative or the additive type of interaction between radon exposure and smoking habit. Six papers discussed the nature of this interaction with a prevalence of the sub-multiplicative model compared to the additive one. Altogether, smoking adjustment did not change significantly lung cancer risk. The included studies might constitute a starting point for updating the models for risk assessment in occupational and residential scenarios, promoting concomitantly the exposure reduction to radon and other cofactors, as recently introduced by Italian Legislative Decree number 101 of 31 July 2020, an application of Euratom Directive 59/2013.

Gini Method Application: Indoor Radon Survey in Kpong, Ghana

In this study, the indoor radon concentrations map, starting from a sparse measurements survey, was realized with the Gini index method. This method was applied on a real dataset coming from indoor radon measurements carried out in Kpong, Ghana. The Gini coefficient variogram is shown to be a good estimator of the inhomogeneity degree of radon concentration because it allows for better constraining of the critical distance below which the radon geological source can be considered as uniform. The indoor radon measurements were performed in 96 dwellings in Kpong, Ghana. The data showed that 84% of the residences monitored had radon levels below 100 Bqm−3, versus 16% having levels above the World Health Organization’s (WHO) suggested reference range (100 Bqm−3). The survey indicated that the average indoor radon concentration (IRC) was 55 ± 36 Bqm−3. The concentrations range from 4–176 Bqm−3. The mean value 55 Bqm−3 is 38% higher than the world’s average IRC of 40 Bqm−3 (UNSCEAR, 1993).

Identification of high radon dwellings, risk of exposure, and geogenic potential in the mining area of the "TREPČA" complex

This study was performed to investigate radon levels in dwellings in the mining area near the town of Kosovska Mitrovica. The Passive radon technique based on the charcoal canister test kit conducted in summer and autumn 2019 showed unexpected results. The reference level of 300 Bq/m³ for indoor radon concentration was exceeded in 15 of 26 dwellings. Preliminary measurements of gamma dose rate in some dwellings built from local stone showed values from 0.30 to 0.45 μSv/h, while 75% of measurements in dwellings with stone foundations had radon above the reference level. The highest radon concentration (22 500 ± 220 Bq/m³ ) was measured in the cellar of one family house. The RAD7 device (Durridge Company, Inc.) was used to measure radon concentrations in water and nearby soil of some dwellings. Indoor radon concentration fluctuated significantly over two days; over a one-day time scale, radon varied from 2843 ± 217 Bq/m³ at midnight to 1449 ± 104 Bq/m³ in the morning at one site, and abruptly decreased from a maximum of 2146 ± 262 Bq/m³ in one day to a minimum of 21 Bq/m³ the next day at another site. The influence of geological substrate on radon exposure was discussed through the estimation of geogenic radon potential, which varies from low the high radon index despite to high permeability of soil.

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.

The evolving landscape of sex-based differences in lung cancer: a distinct disease in women

In stark contrast to a few decades ago when lung cancer was predominantly a disease of men who smoke, incidence rates of lung cancer in women are now comparable to or higher than those in men and are rising alarmingly in many parts of the world. Women face a unique set of risk factors for lung cancer compared to men. These include exogenous exposures including radon, prior radiation, and fumes from indoor cooking materials such as coal, in addition to endogenous exposures such as oestrogen and distinct genetic polymorphisms. Current screening guidelines only address tobacco use and likely underrepresent lung cancer risk in women. Women were also not well represented in some of the landmark prospective studies that led to the development of current screening guidelines. Women diagnosed with lung cancer have a clear mortality benefit compared to men even when other clinical and demographic characteristics are accounted for. However, there may be sex-based differences in outcomes and side effects of systemic therapy, particularly with chemotherapy and immunotherapy. Ongoing research is needed to better investigate these differences to address the rapidly changing demographics of lung cancer worldwide.

Sex-based differences in lung cancer span the care continuum. This suggests lung cancer may increasingly be viewed as a distinct disease in women, with implications for screening and treatment. Lung cancer research should capture these sex-based differences.https://bit.ly/2WfhaB4

Estimation of lung cancer deaths attributable to indoor radon exposure in upper northern Thailand

Radon exposure is the second leading cause of lung cancer, after smoking. In upper northern Thailand (UNT), lung cancer incidence was frequently reported by Thailand National Cancer Institute. Besides smoking, radon exposure may also influence the high lung cancer incidence in this region. Indoor radon concentrations were measured in 192 houses in eight provinces of UNT. Indoor radon concentrations ranged from 11 to 405 Bq m⁻³ and estimated annual effective dose ranged from 0.44 to 12.18 mSv y⁻¹. There were significant differences in indoor radon concentrations between the houses of lung cancer cases and healthy controls (p = 0.033). We estimated that 26% of lung cancer deaths in males and 28% in females were attributable to indoor radon exposure in this region. Other factors influencing indoor radon levels included house characteristics and ventilation. The open window-to-wall ratio was negatively associated with indoor radon levels (B = −0.69, 95% CI −1.37, −0.02) while the bedroom location in the house and building material showed no association. Indoor radon hence induced the fractal proportion of lung cancer deaths in UNT.

Indoor Radon Monitoring in Kindergarten and Primary Schools in South Italy

Humans are mostly exposed to ionizing radiation through radon and its decay products. The results of indoor radon measurements in 39 kindergartens and primary schools in the Campania region of southern Italy are presented in this paper. The survey was carried out with CR-39 solid-state nuclear track detectors (SSNTDs). Radon concentrations were measured and ranged from 11 to 1416 Bq/m3, with a geometric mean of 77 Bq/m3 and a geometric standard deviation of 2. The findings revealed that 70% of the measures were below the WHO recommended level of 100 Bq/m3 and that 97 percent of the measurements were below the 300 Bq/m3 level set by Italian law.

Evaluating and Assessing Radon Testing in Multifamily Housing

CONTEXT

To determine if radon mitigation is needed to protect occupants of multifamily housing, reliable testing procedures are needed. Yet, protocols on how many ground-contact housing units must be tested vary from 10% to 25% to 100%.

OBJECTIVES

To estimate the probability of failing to identify a building containing at least one unit with elevated radon level when all ground-contact units are not tested.

DESIGN

Retrospective analysis of previously collected data from licensed (ie, certified) radon measurement professionals using hypergeometric and Monte Carlo statistical methods to estimate the confidence that there are no units with radon levels of 4 picoCuries/liter of air (pCi/L) or more based on various testing percentages.

SETTING

Testing data were obtained from 29 US states for 7892 ground-contact units in 687 multifamily buildings, primarily 5 to 20 units per building.

MAIN OUTCOME MEASURE

Probability of failing to identify elevated radon levels in untested units.

RESULTS

About 15% (n = 1163) of the units had radon levels of more than 4 pCi/L (the EPA action level); 59 units had more than 20 pCi/L (maximum of 96 pCi/L). For building sizes of 5 to 20 ground-contact units, the 2018 federal testing protocols that currently require testing of 10% and 25% of ground-contact units in each building failed to identify 47%-69% and 32%-46% of the units, respectively, depending on building size.

CONCLUSIONS

Measurement of 90% of the ground-contact units in buildings with 5 to 20 ground-contact units results in up to 4% of the units with elevated radon levels being missed. To achieve 95% confidence that no units in the building have radon levels of 4 pCi/L or more in buildings up to 20 units, 100% sampling is required. For the vast majority of multifamily buildings, all ground-contact units in multifamily buildings should be tested for radon.

Designing a Multicriteria WebGIS-Based Pre-Diagnosis Tool for Indoor Radon Potential Assessment

Radon (222Rn) is a well-known source of indoor air contamination since in its gaseous form it is a reported source of ionizing radiation that belongs to the group of rare gases. Radon occurs naturally in soils and rocks and results from the radioactive decay of its longer-lived progenitors, i.e., radium, uranium, and thorium. Radon releases itself from the soil and rocks, which mainly occurs in outdoor environments, not causing any kind of impact due to its fast dilution into the atmosphere. However, when this release occurs in confined and poorly ventilated indoor environments, this release can result in the accumulation of high concentrations of radon gas, being recognized by the World Health Organization (WHO) as the second cause of lung cancer, after smoking. Assessing the indoor radon concentration demands specific know-how involving the implementation of several time-consuming tasks that may include the following stages: (1) radon potential assessment; (2) short-term/long-term radon measurement; (3) laboratory data analysis and processing; and (4) technical reporting. Thus, during stage 1, the use of indirect methods to assess the radon occurrence potential, such as taking advantage of existent natural radiation maps (which have been made available by the uranium mineral prospecting campaigns performed since the early 1950s), is crucial to put forward an ICT (Information and Communication Technology) platform that opens up a straightforward approach for assessing indoor radon potential at an early stage, operating as a pre-diagnosis evaluation tool that is of great value for supporting decision making towards the transition to stage 2, which typically has increased costs due to the need for certified professionals to handle certified instruments for short-term/long-term radon measurement. As a pre-diagnosis tool, the methodology proposed in this article allows the assessment of the radon potential of a specific building through a WebGIS-based platform that adopts ICT and Internet technologies to display and analyze spatially related data, employing a multicriteria approach, including (a) gamma radiation maps, (b) built environment characteristics, and (c) occupancy profile, and thus helping to determine when the radon assessment process should proceed to stage 2, or, alternatively, by eliminating the need to perform additional actions.

Imputation by feature importance (IBFI): A methodology to envelop machine learning method for imputing missing patterns in time series data

A new methodology, imputation by feature importance (IBFI), is studied that can be applied to any machine learning method to efficiently fill in any missing or irregularly sampled data. It applies to data missing completely at random (MCAR), missing not at random (MNAR), and missing at random (MAR). IBFI utilizes the feature importance and iteratively imputes missing values using any base learning algorithm. For this work, IBFI is tested on soil radon gas concentration (SRGC) data. XGBoost is used as the learning algorithm and missing data are simulated using R for different missingness scenarios. IBFI is based on the physically meaningful assumption that SRGC depends upon environmental parameters such as temperature and relative humidity. This assumption leads to a model obtained from the complete multivariate series where the controls are available by taking the attribute of interest as a response variable. IBFI is tested against other frequently used imputation methods, namely mean, median, mode, predictive mean matching (PMM), and hot-deck procedures. The performance of the different imputation methods was assessed using root mean squared error (RMSE), mean squared log error (MSLE), mean absolute percentage error (MAPE), percent bias (PB), and mean squared error (MSE) statistics. The imputation process requires more attention when multiple variables are missing in different samples, resulting in challenges to machine learning methods because some controls are missing. IBFI appears to have an advantage in such circumstances. For testing IBFI, Radon Time Series Data (RTS) has been used and data was collected from 1st March 2017 to the 11th of May 2018, including 4 seismic activities that have taken place during the data collection time.

Superoxide dismutase and glutathione peroxidase activities in a population exposed to high indoor radon concentration: a preliminary report

The objective of this study was to assess the effect of radon exposure on the modulation of endogenous antioxidants in a population chronically exposed to high levels of radon indoors. To do so, we measured the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in peripheral blood mononuclear cells (PBMCs) of people living in an area with high indoor radon concentration (Tande-Tande sub-village, Indonesia). The activities of SOD and GPX in Tande-Tande inhabitants were compared with those in subjects living in the Topoyo village (Indonesia), an area with low indoor radon levels. The activities of SOD and GPX in Tande-Tande sub-village inhabitants did not differ from those in people living in the Topoyo village (0.37 ± 0.021 versus 0.28 ± 0.018 U/mg protein and 8.46 ± 1.48 versus 8.34 ± 1.65 U/mg protein, p > .05). For both populations, there was a significant positive correlation between SOD and GPX activities (p < .001). No significant effects of gender, age, smoking habit, and body mass index on SOD and GPX activities were found for both groups. Although no significant modulation of SOD and GPX activities in PBMCs was detected, further studies should expand the sample size and also assess antioxidant levels in the serum. This study provides a first picture of endogenous antioxidant systems in Tande-Tande sub-village inhabitants, but a more comprehensive analysis, including the measurement of catalase (CAT) activity, might provide additional insight into the effects of chronic exposure to high indoor radon concentrations.

The First Attempt to Reevaluate Radon and Thoron Exposure in Gansu Province Study Using Radon-Thoron Discriminating Measurement Technique

Although the epidemiological studies provide evidence for an increased risk of lung cancer risk associated with residential radon, an issue of radon-thoron discrimination remains to be solved. In this study, an updated evaluation of lung cancer risk among the residents in Gansu, China was performed where one of the major epidemiological studies on indoor radon demonstrated an increased risk of lung cancer. We analyzed data from a hospital-based case-control study that included 30 lung cancer cases and 39 controls with special attention to internal exposure assessment based on the discriminative measurement technique of radon isotopes. Results from the analyses showed non-significant increased lung cancer risks; odds ratios (ORs) adjusted for age, smoking, and total income were 0.35 (95% CI: 0.07–1.74) and 0.27 (95% CI: 0.04–1.74) for groups living in residences with indoor radon concentrations of 50–100 Bq m⁻³ and over 100 Bq m⁻³, respectively, compared with those with < 50 Bq m⁻³ indoor radon concentrations. Although the small sample size hampers the usefulness of present analyses, our study suggests that reevaluation of lung cancer risk associated with residential radon in the epidemiological studies will be required on the basis of precise exposure assessment.

Regional cost effectiveness analyses for increasing radon protection strategies in housing in Canada

The incremental cost effectiveness ratios for implementing a recent recommendation to install a more radon resistant foundation barrier were modelled for new and existing housing in 2016, for each province and territory in Canada. Cost-utility analyses were conducted, in which the health benefit of an intervention was quantified in quality-adjusted life years, to help guide policymakers considering increasing investment in radon reduction in housing to reduce the associated lung cancer burden shouldered by the health care system. Lung cancer morbidity was modelled using a lifetable analysis that incorporated lung cancer incidence and survival time for localized, regional, and distant stages of diagnoses for both non-small cell and small cell lung cancer. The model accounted for surgical or advanced lung cancer treatment costs avoided, and average health care costs incurred for radon-attributable lung cancer cases prevented by the intervention. The incremental implementation of radon interventions in the housing stock was modelled over a lifetime horizon, and a discount rate of 1.5% was adopted. This radon intervention in new housing was cost effective in all but one region, ranging from $18,075/QALY (15,704; 20,178) for the Yukon to $58,454/QALY (52,045; 65,795) for British Columbia. A sequential analysis was conducted to compare intervention in existing housing for mitigation thresholds of 200 and 100 Bq/m³. This intervention in existing housing was cost effective at a mitigation threshold of 200 Bq/m³ in regions with higher radon levels, ranging from $33,247/QALY (27,699; 39,377) for the Yukon to $61,960/QALY (46,932; 113,737) for Newfoundland, and more cost effective at a threshold of 200 than 100 Bq/m³. More lung cancer deaths can be prevented by intervention in new housing than in existing housing; it was estimated that the proposed intervention in new housing would prevent a mean of 446 (416; 477) lung cancer cases annually. The cost effectiveness of increased radon resistance in foundation barriers in housing varied widely, and would support adopting this intervention in new housing across Canada and in existing housing in higher radon regions. This study provides further evidence that the most cost effective way of responding to the geographically variable radon burden is by implementing specific regional radon reduction policies.

Lung cancer risk in never-smokers: An overview of environmental and genetic factors

Lung cancer is the leading cause of cancer-related mortality globally, accounting for 1.8 million deaths in 2020. While the vast majority are caused by tobacco smoking, 15%-25% of all lung cancer cases occur in lifelong never-smokers. The International Agency for Research on Cancer (IARC) has classified multiple agents with sufficient evidence for lung carcinogenesis in humans, which include tobacco smoking, as well as several environmental exposures such as radon, second-hand tobacco smoke, outdoor air pollution, household combustion of coal and several occupational hazards. However, the IARC evaluation had not been stratified based on smoking status, and notably lung cancer in never-smokers (LCINS) has different epidemiological, clinicopathologic and molecular characteristics from lung cancer in ever-smokers. Among several risk factors proposed for the development of LCINS, environmental factors have the most available evidence for their association with LCINS and their roles cannot be overemphasized. Additionally, while initial genetic studies largely focused on lung cancer as a whole, recent studies have also identified genetic risk factors for LCINS. This article presents an overview of several environmental factors associated with LCINS, and some of the emerging evidence for genetic factors associated with LCINS. An increased understanding of the risk factors associated with LCINS not only helps to evaluate a never-smoker's personal risk for lung cancer, but also has important public health implications for the prevention and early detection of the disease. Conclusive evidence on causal associations could inform longer-term policy reform in a range of areas including occupational health and safety, urban design, energy use and particle emissions, and the importance of considering the impacts of second-hand smoke in tobacco control policy.

Environmental/Occupational Exposure to Radon and Non-Pulmonary Neoplasm Risk: A Review of Epidemiologic Evidence

Although Radon (Rn) is a known agent for lung cancer, the link between Rn exposure and other non-pulmonary neoplasms remains unclear. The aim of this review is to investigate the role of Rn in the development of tumors other than lung cancer in both occupational and environmental exposure. Particularly, our attention has been focused on leukemia and tumors related to brain and central nervous system (CNS), skin, stomach, kidney, and breast. The epidemiologic literature has been systematically reviewed focusing on workers, general population, and pediatric population. A weak increase in leukemia risk due to Rn exposure was found, but bias and confounding factors cannot be ruled out. The results of studies conducted on stomach cancer are mixed, although with some prevalence for a positive association with Rn exposure. In the case of brain and CNS cancer and skin cancer, results are inconclusive, while no association was found for breast and kidney cancers. Overall, the available evidence does not support a conclusion that a causal association has been established between Rn exposure and the risk of other non-pulmonary neoplasms mainly due to the limited number and heterogeneity of existing studies. To confirm this result, a statistical analysis should be necessary, even if it is now not applicable for the few studies available.

ATS Core Curriculum 2021. Adult Pulmonary Medicine: Thoracic Oncology

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine at the annual international conference. The 2021 Pulmonary Core Curriculum focuses on lung cancer and include risks and prevention, screening, nodules, therapeutics and associated pulmonary toxicities, and malignant pleural effusions. Although tobacco smoking remains the primary risk factor for developing lung cancer, exposure to other environmental and occupational substances, including asbestos, radon, and burned biomass, contribute to the global burden of disease. Randomized studies have demonstrated that routine screening of high-risk smokers with low-dose chest computed tomography results in detection at an earlier stage and reduction in lung cancer mortality. On the basis of these trials and other lung cancer risk tools, screening recommendations have been developed. When evaluating lung nodules, clinical and radiographic features are used to estimate the probability of cancer. Management guidelines take into account the nodule size and cancer risk estimates to provide recommendations at evaluation. Newer lung cancer therapies, including immune checkpoint inhibitors and molecular therapies, cause pulmonary toxicity more frequently than conventional chemotherapy. Treatment-related toxicity should be suspected in patients receiving these medications who present with respiratory symptoms. Evaluation is aimed at excluding other etiologies, and treatment is based on the severity of symptoms. Malignant pleural effusions can be debilitating. The diagnosis is made by using simple pleural drainage and/or pleural biopsies. Management depends on the clinical scenario and the patient's preferences and includes the use of serial thoracentesis, a tunneled pleural catheter, or pleurodesis.

EFFECTIVE DOSE COEFFICIENTS FOR RADON AND PROGENY: A REVIEW OF ICRP AND UNSCEAR VALUES

The International Commission on Radiological Protection (ICRP) publishes guidance on protection against radon exposure in homes and workplaces. ICRP Publication 137 recommends a dose coefficient of 3 mSv per mJ h m-3 (~10 mSv WLM-1) to be used in most circumstances of radon exposure, for workers in buildings and in underground mines. Recently, United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reviewed radon epidemiology and dosimetry and concluded that its established dose coefficient of 1.6 mSv per mJ h m-3 (5.7 mSv WLM-1) should be retained for use in its comparisons of radiation exposures from different sources in a population. This paper explains and compares the reviews of the scientific evidence from UNSCEAR and ICRP. It is shown that the UNSCEAR and ICRP reviews are consistent and support the use of the ICRP reference dose coefficients for radiation protection purposes. It is concluded that the ICRP dose coefficient should be used to calculate doses to workers.

Simulation study on the validity of the average risk approach in estimating population attributable fractions for continuous exposures

BACKGROUND

The population attributable fraction (PAF) is an important metric for estimating disease burden associated with causal risk factors. In an International Agency for Research on Cancer working group report, an approach was introduced to estimate the PAF using the average of a continuous exposure and the incremental relative risk (RR) per unit. This 'average risk' approach has been subsequently applied in several studies conducted worldwide. However, no investigation of the validity of this method has been done.

OBJECTIVE

To examine the validity and the potential magnitude of bias of the average risk approach.

METHODS

We established analytically that the direction of the bias is determined by the shape of the RR function. We then used simulation models based on a variety of risk exposure distributions and a range of RR per unit. We estimated the unbiased PAF from integrating the exposure distribution and RR, and the PAF using the average risk approach. We examined the absolute and relative bias as the direct and relative difference in PAF estimated from the two approaches. We also examined the bias of the average risk approach using real-world data from the Canadian Population Attributable Risk of Cancer study.

RESULTS

The average risk approach involves bias, which is underestimation or overestimation with a convex or concave RR function (a risk profile that increases more/less rapidly at higher levels of exposure). The magnitude of the bias is affected by the exposure distribution as well as the value of RR. This approach is approximately valid when the RR per unit is small or the RR function is approximately linear. The absolute and relative bias can both be large when RR is not small and the exposure distribution is skewed.

CONCLUSIONS

We recommend that caution be taken when using the average risk approach to estimate PAF.

Analysis of Indoor Radon Data Using Bayesian, Random Binning, and Maximum Entropy Methods

Three statistical methods: Bayesian, randomized data binning and Maximum Entropy Method (MEM) are described and applied in the analysis of US radon data taken from the US registry. Two confounding factors-elevation of inhabited dwellings, and UVB (ultra-violet B) radiation exposure-were considered to be most correlated with the frequency of lung cancer occurrence. MEM was found to be particularly useful in extracting meaningful results from epidemiology data containing such confounding factors. In model testing, MEM proved to be more effective than the least-squares method (even via Bayesian analysis) or multi-parameter analysis, routinely applied in epidemiology. Our analysis of the available residential radon epidemiology data consistently demonstrates that the relative number of lung cancers decreases with increasing radon concentrations up to about 200 Bq/m³, also decreasing with increasing altitude at which inhabitants live. Correlation between UVB intensity and lung cancer has also been demonstrated.

Residential radon and lung cancer characteristics at diagnosis

PURPOSE

This study sought to ascertain whether there might be an association between radon concentrations and age, gender, histologic type, and tumor stage at diagnosis.

MATERIALS AND METHODS

Lung cancer cases from different multicenter case-control studies were analyzed, and clinical data were retrieved from electronic health records and personal interviews. A radon device was placed in all dwellings of participants, and we then tested the existence of an association between residential radon and lung cancer characteristics at diagnosis.

RESULTS

Of the total of 829 lung cancer cases included, 56.7% were smokers or ex-smokers. There was no association between indoor radon concentrations and age, gender, histologic type or tumor stage at diagnosis. Median indoor radon concentrations increased with age at diagnosis for men, but not for women. When analyzing participants exposed to more than 1000 Bq/m³, a predominance of small cell lung cancer and a higher presence of advanced stages (IIIB and IV) were observed.

CONCLUSIONS

There seems to be no association between radon and age, gender, histologic type or tumor stage at diagnosis. Higher radon exposure is more frequent in the case of small-cell lung cancer.