RESUMO
Epidemiological studies proved that cumulative exposure to radon is the second leading cause of lung cancer, the world's most common cancer. The objectives of the present study are (i) to analyse lung cancer risk for chronic, low radon exposures based on the transformation frequency-tissue response (TF-TR) model formulated in terms of alpha particle hits in cell nuclei; (ii) to assess the percentage of attributable lung cancers in six areas of Transylvania where the radon concentration was measured and (iii) to point out the most efficient remediation measures tested on a pilot house in Stei, Romania. Simulations performed with the TF-TR model exhibit a linear dose-effect relationship for chronic, residential radon exposures. The fraction of lung cancer cases attributed to radon ranged from 9 to 28% for the investigated areas. Model predictions may represent a useful tool to complement epidemiological studies on lung cancer risk and to establish reasonable radiation protection regulations for human safety.
Assuntos
Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Neoplasias Pulmonares/prevenção & controle , Modelos Estatísticos , Neoplasias Induzidas por Radiação/prevenção & controle , Monitoramento de Radiação , Radônio/análise , Poluentes Radioativos do Ar/efeitos adversos , Poluição do Ar em Ambientes Fechados/efeitos adversos , Relação Dose-Resposta à Radiação , Habitação , Humanos , Neoplasias Pulmonares/etiologia , Neoplasias Induzidas por Radiação/etiologia , Proteção Radiológica , Radônio/efeitos adversos , Fatores de Risco , Romênia , Urânio/efeitos adversosRESUMO
To determine radiation doses incurred by inhaled thoron progeny, the Monte Carlo radon progeny lung dosimetry code IDEAL-DOSE was adapted to the inhalation of thoron progenies, comprising the alpha-emitting nuclides 216Po, 212Bi and 212Po. Dose calculations for defined exposure conditions yielded a dose conversion coefficient (DCC) of 4.6 mSv WLM(-1) or 94.2 nSv (Bq h m(-3))(-1) when compared with a DCC of 3.8 mSv WLM(-1) if based on the International Commission on Radiological Protection Human Respiratory Tract Model. Bronchial doses were computed for different thoron progenies exposure conditions measured in a Bavarian half-timbered house and in a thoron experimental house at the Helmholtz Zentrum München. DCCs ranged from 4.9 to 12.9 mSv WLM(-1), depending on particle size, unattached fraction and fractional activity concentrations. For exposure-specific indoor aerosol parameters, the thoron progeny DCC is smaller than the radon progeny DCC by about a factor of 2.