Residential radon exposure and cancer

Issue 2 - "Update on adverse respiratory effects of indoor air pollution" Part 1): Indoor air pollution and respiratory diseases: A general update and a Portuguese perspective

OBJECTIVE

To quantify the impact of different air pollutants on respiratory health based on robust estimates based on international data and to summarise the evidence of associations between indoor exposure to those pollutants and respiratory morbidity in the Portuguese population.

RESULTS

Several systematic reviews and meta-analyses (MA) at the world level demonstrate the impact of indoor air quality on respiratory health, with indoor particulate matter and gasses exerting a significant effect on the airways. Volatile organic compounds (VOC) have been related to asthma and lung cancer. However, only meta-analyses on biomass use allowed documentation of long-term respiratory effects. While early publications concerning Portuguese-based populations mainly focused on indoor exposure to environmental tobacco smoke, later studies relocated the attention to relevant exposure environments, such as day care buildings, schools, residences and nursing homes. Looking at the pooled effects from the reviewed studies, high levels of carbon dioxide and particulate matter in Portuguese buildings were significantly associated with asthma and wheezing, with VOC and fungi showing a similar effect in some instances.

CONCLUSIONS

Despite the significant reduction of indoor air pollution effects after the 2008 indoor smoking prohibition in public buildings, studies show that several indoor air parameters are still significantly associated with respiratory health in Portugal. The country shares the worldwide necessity of standardisation of methods and contextual data to increase the reach of epidemiological studies on household air pollution, allowing a weighted evaluation of interventions and policies focused on reducing the associated respiratory morbidity.

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.

Impact of Indoor Radon Exposure on Lung Cancer Incidence in Slovenia

Indoor radon is an important risk factor for lung cancer, as 3-14% of lung cancer cases can be attributed to radon. The aim of our study was to estimate the impact of indoor radon exposure on lung cancer incidence over the last 40 years in Slovenia. We analyzed the distribution of lung cancer incidence across 212 municipalities and 6032 settlements in Slovenia. The standardized incidence ratios were smoothed with the Besag-York-Mollie model and fitted with the integrated nested Laplace approximation. A categorical explanatory variable, the risk of indoor radon exposure with low, moderate and high risk values, was added to the models. We also calculated the population attributable fraction. Between 2.8% and 6.5% of the lung cancer cases in Slovenia were attributable to indoor radon exposure, with values varying by time period. The relative risk of developing lung cancer was significantly higher among the residents of areas with a moderate and high risk of radon exposure. Indoor radon exposure is an important risk factor for lung cancer in Slovenia in areas with high natural radon radiation (especially in the southern and south-eastern parts of the country).

Radon exposure: a major cause of lung cancer in nonsmokers

Exposure to radon can impact human health. This is a nonsystematic review of articles written in English, Spanish, French, or Portuguese published in the last decade (2013-2023), using databases such as PubMed, Google Scholar, EMBASE, and SciELO. Search terms selected were radon, human health, respiratory diseases, children, and adults. After analyzing the titles and abstracts, the researchers initially identified 47 studies, which were subsequently reduced to 40 after excluding reviews, dissertations, theses, and case-control studies. The studies have shown that enclosed environments such as residences and workplaces have higher levels of radon than those outdoors. Moreover, radon is one of the leading causes of lung cancer, especially in nonsmokers. An association between exposure to radon and development of other lung diseases, such as asthma and COPD, was also observed. It is crucial to increase public awareness and implement governmental control measures to reduce radon exposure. It is essential to quantify radon levels in all types of buildings and train professionals to conduct such measurements according to proven efficacy standards. Health care professionals should also be informed about this threat and receive adequate training to deal with the effects of radon on human health.

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.

Opportunities and Challenges of Kava in Lung Cancer Prevention

Lung cancer is the leading cause of cancer-related deaths due to its high incidence, late diagnosis, and limited success in clinical treatment. Prevention therefore is critical to help improve lung cancer management. Although tobacco control and tobacco cessation are effective strategies for lung cancer prevention, the numbers of current and former smokers in the USA and globally are not expected to decrease significantly in the near future. Chemoprevention and interception are needed to help high-risk individuals reduce their lung cancer risk or delay lung cancer development. This article will review the epidemiological data, pre-clinical animal data, and limited clinical data that support the potential of kava in reducing human lung cancer risk via its holistic polypharmacological effects. To facilitate its future clinical translation, advanced knowledge is needed with respect to its mechanisms of action and the development of mechanism-based non-invasive biomarkers in addition to safety and efficacy in more clinically relevant animal models.

Immune senescence in non-small cell lung cancer management: therapeutic relevance, biomarkers, and mitigating approaches

INTRODUCTION

Lung cancer and mainly non-small cell lung cancer (NSCLC) still remain a prevalent malignancy worldwide despite sustained screening approaches. Furthermore, a significant proportion of the cases are diagnosed at advanced stages when conservative therapy is often unsuccessful. Cell senescence is an endogenous antitumor weapon but when it is upregulated exerts opposite activities favoring tumor metastasizing and poor response to therapy. However, little is known about this dangerous relationship between cell senescence and NSCLC outcome or on potential approaches to mitigate its unfavorable consequences.

AREAS COVERED

We discuss cell senescence focusing on immune senescence, its cell and humoral effectors (namely immune senescence associated secretory phenotype-iSASP), its impact on NSCLC outcome, and its biomarkers. Senotherapeutics as mitigating approaches are also considered based on the availability of experimental data pertinent to NSCLC.

EXPERT OPINION

Characterization of NSCLC subsets in which immune senescence is a risk factor for poor prognosis and poor therapeutic response might be very helpful in supporting the addition of senotherapeutics to conventional cancer therapy. This approach has the potential to improve disease outcome but more studies in this area are necessary.

Radiological risk estimation from indoor radon, thoron, and their progeny concentrations using nuclear track detectors

In this paper, we report the results of seasonal variations of indoor radon and thoron concentrations, equilibrium factors for gas progeny, and radiological risks to dwellers in the hilly area of Guwahati City, Assam, India. Twin-cup dosemeters with LR-115 (II) nuclear track detectors were used in this study. The findings show that values vary significantly, with winter having the highest values and summer having the lowest, with spring and autumn having moderate values. In winter, radon concentrations range from 61.6 ± 11.2 Bq m^-3 (Mud) to 115.3 ± 34.3 Bq m^-3 (AT), with geometric mean values of 69.2 ± 13.8 Bq m^-3 and 109.4 ± 27.9 Bq m^-3, and in summer, they range from 21.1 ± 5.9 Bq m^-3 (Mud) to 28.4 ± 8.3 Bq m^-3 (AT), with geometric mean values of 22.7 ± 6.3 Bq m^-3 and 26.1 ± 7.1 Bq m^-3, whereas thoron concentrations range from 13.1 ± 5.1 Bq m^-3 (Mud) to 58.8 ± 12.6 Bq m^-3 (AT), with geometric mean values of 27.6 ± 7.0 Bq m^-3 and 52.9 ± 10.1 Bq m^-3 in winter, respectively, and in summer, from 8.8 ± 2.3 Bq m^-3 (Mud) to 13.0 ± 5.5 Bq m^-3 (Mud), with a geometric mean value of 1.87 ± 1.29 Bq m^-3. Radon and thoron progeny levels are reported to vary from 4.1 ± 0.3 mWL (Mud) to 15.1 ± 4.3 mWL (AT) and 2.6 ± 0.9 mWL (Mud) to 14.3 ± 4.2 mWL (AT) in winter and from 1.5 ± 0.7 mWL (AT) to 3.0 ± 2.5 mWL (Mud) and 0.9 ± 0.3 mWL (AT) to 2.7 ± 0.5 mWL (Mud) in summer, respectively. The equilibrium factors for radon and its progeny have been reported to range from 0.23 ± 0.1 (Mud) to 0.51 ± 0.3 (AT) in winter, whereas from 0.23 ± 0.1 (AT) to 0.48 ± 0.4 (Mud) in summer, respectively. The equilibrium factors for thoron and its progeny have been estimated in the range of 0.02 ± 0.01 (Mud) to 0.09 ± 0.06 (AT) in winter, whereas 0.02 ± 0.02 (AT) to 0.07 ± 0.05 (Mud) in summer, respectively. The inhalation dose rates differed from house to house, having values in the range of 1.2 ± 0.2 mSv year^-1 (Mud) to 4.6 ± 1.3 mSv year^-1 (AT) in winter, whereas 0.5 ± 0.3 mSv year^-1 (AT) to 0.9 ± 0.5 mSv year^-1 (Mud) in summer, respectively. The effective doses (EDs) due to the exposure of radon and thoron in the study area have been found to range from 2.5 ± 0.3 mSv (Mud) to 9.1 ± 2.7 mSv (AT) in winter and 0.9 ± 0.4 mSv (AT) to 1.8 ± 1.3 mSv (Mud) in summer, respectively. The levels of radon and thoron in similar types of construction were found to be significantly different from one house to another. The estimated radon and thoron concentrations in the houses of that region during winter are found to be substantially higher than the global averages as reported by UNSCEAR.