Prediction of lung cancer risk for radon exposures based on cellular alpha particle hits

Abstract

To explore the role of the multiplicity of cellular hits by radon progeny alpha particles for lung cancer incidence, the number of single and multiple alpha particle hits were computed for basal and secretory cells in the bronchial epithelium of human airway bifurcations. Hot spots of alpha particle hits were observed at the branching points of bronchial airway bifurcations. The effect of single and multiple alpha particle intersections of bronchial cells during a given exposure period, selected from a Poisson distribution, on lung cancer risk were simulated by a transformation frequency--tissue response model, based on experimentally observed cellular transformation and survival functions. Calculations of lung cancer risk at low radon exposure levels suggest that single hits produce a linear-dose response relationship, while the superposition of single and increasing multiple hits at higher exposure levels may also be approximated by a quasi-linear dose-effect curve. The simulations predict a carcinogenic enhancement effect for radon progeny accumulations at bifurcation branching sites, which may increase current risk estimates.

Radon Concentrations Measurement in Aljouf, Saudi Arabia Using Active Detecting Method

“…Researches carried out in recent decade's show, under normal conditions, ingestion of natural radioactive gas radon 222 Rn and its decay products. Long term exposures to radon via inhalation in closed rooms or caves or open air saturated with radon gas are the cause of about 10 % of all deaths from lung cancer [8]. Studied also related to radon in kidney and malignant melanoma cancer have been reported [9].…”

Multiple Stressor Effects of Radon and Phthalates in Children: Background Information and Future Research

“…Generally speaking, ionizing radiations can inflict damages to molecules of deoxyribonucleic acid (DNA) in cells in our body, such as single-strand breaks (SSBs), double-strand breaks (DSBs), and base damages [39,40], and the subsequent loss of genetic integrity can lead to mutation and induce cancer. In particular, α-particles have high linear-energy-transfer (LET) values and can deliver large doses locally to promote carcinogenesis in the bronchial and bronchiolar epithelia (see Section 2.3 below) [29,39,[41][42][43].…”

Internal microdosimetry of alpha-emitting radionuclides

“…For alpha-emitting radon progeny activities on bronchial airways surface, computed hit probabilities for single and multiple hits in sensitive bronchial target cells, assuming a Poisson distribution, combined with average cellular doses, provide a more realistic basis for resulting cellular radiobiological effects than an average tissue dose. For example, calculations of frequencies of single and multiple cellular alpha particle hits in bronchial target cells have been published by Balásházy et al (2009), Crawford-Brown (1988), Fakir et al (2005b), Farkas et al (2011), Harley (1988), Hofmann et al (1994Hofmann et al ( , 2002, Hui et al (1990), Madas (2016), Nikezic and Yu (2001), Sedlák (1996), Szoke et al (2006Szoke et al ( , 2009Szoke et al ( , 2012 and Truta-Popa et al (2011a). Important findings from a dosimetric point of view are: (1) hit probabilities decrease in a nearly linear manner with increasing depth in bronchial tissue, (2) for typical indoor radon progeny activity concentrations, only few target cells are hit during the lifetime of these cells and multiple hits will play a role only for cells located at airway bifurcations due to the localized radon progeny accumulations, and, (3) the frequency of cellular hits increases with rising radon progeny activities from low domestic to high uranium miner exposures where multiple hits have to be considered.…”