The “Polonium In Vivo” Study: Polonium-210 in Bronchial Lavages of Patients with Suspected Lung Cancer

Abstract

Few studies have reported on polonium-210, a decay breakdown product of radon-222 and lead-210, in human lungs and there has been no study in patients with suspected lung cancer. The main aim of this “Polonium in vivo” study was to evaluate polonium-210 radioactivity in bronchopulmonary systems of smoker, ex-smoker and never smoker patients with suspected lung cancer. Alpha-spectrometric analyses were performed on bronchial lavage (BL) fluids from two Italian hospitals in 2013–2016. Socio-demographic, smoking, occupational and spirometric characteristics, lung cancer confirmation and histologic type and radon-222 concentration in patients’ homes were collected. Seventy BL samples from never (n = 13), former (n = 35) and current smokers (n = 22) were analyzed; polonium-210 was detected in all samples from current and former smokers and in 54% of samples from never smokers (p < 0.001; median values: 1.20, 1.43 and 0.40 mBq, respectively). Polonium-210 levels were significantly higher in COPD versus no COPD patients (median value: 3.60 vs. 0.97 mBq; p = 0.007); former and current smokers, without and with COPD, had significantly increased polonium-210 levels (p = 0.012); 96% of confirmed versus 69% of non-confirmed lung cancer patients recorded detectable polonium-210 levels (p = 0.018). A polonium-210 detectable activity was measured in BL samples from all current and former smokers. Polonium-210 in the lungs could be the result of lead-210 entrapment, which, with its half-life of 22 years, could provide a continuous emission of alpha radioactivity, even many years after quitting, thus proposing a possible explanation for the onset of lung cancer, particularly in former smokers.

Ruolo del cadmio nelle patologie correlate all’uso di tabacco

“…Tra questi il polonio 210 , prodotto di decadimento del radon 222 e del piombo 210 , è ritrovato nel BAL di fumatori cronici con Broncopneumopatia Cronico Ostruttiva (BPCO) a causa dell'intrappolamento del piombo sull'epitelio bronchiale dovuto all'inefficienza della clearance mucociliare. Tale condizione permette il rilascio prolungato (per molti anni) di radiazioni alfa che hanno un notorio effetto cancerogeno e proinfiammatorio [2]. Il Cd, così come l'arsenico, il mercurio e il cromo, è un metallo pesante che non svolge funzioni fisiologiche (tranne che in una microalga diatomea unicellulare, che vive in un ambiente povero di zinco, ove è il catalizzatore di un'anidrasi carbonica) ed è considerato solo un agente tossico.…”