The distribution of the number of alpha hits per target cell: a new parameter to improve risk assessment for cancer induction using ICRP models.
Doses are calculated from the total energy deposited within the different target regions of the organism. After inhalation exposure, only a few particles can be deposited within the respiratory tract that induces a heterogeneous dose distribution. A decrease in risk for lung tumours induction associated to the presence of hot spots has been reported. This was partly explained by a decrease in the transformation rate per gray when cells received more than one alpha hit. This study provides an estimate of the distribution of alpha hits per target cell of the extra thoracic region (ET2), after inhalation exposure to 238UO2, 239PuO2 or 238PuO2, obtained by a stochastic application of the biokinetic and dosimetric ICRP models. After exposure to one annual limit of intake, homogeneous irradiation of the target cells is observed for 238UO2, whereas, for PuO2, most of the dose is due to cells receiving daily tens or even hundreds of alpha hits. This underlines the uncertainties in risk assessment associated with a dose rate effect.
Fritsch
P
P
Laboratoire de Radiotoxicologie, SRCA/DRR/DSV/CEA, BP 12, 91680 Bruyères le Châtel, France. paul.fritsch@cea.fr
D000336:Aerosols / Q000032:analysis / Q000493:pharmacokinetics; D000512:Alpha Particles; D001681:Biological Assay / Q000379:methods; D002468:Cell Physiological Phenomena / Q000528:radiation effects; D003198:Computer Simulation; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D008168:Lung / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism*; D008954:Models, Biological; D009381:Neoplasms, Radiation-Induced / Q000378:metabolism*; D009928:Organ Specificity; D011829:Radiation Dosage; D011868:Radioisotopes / Q000493:pharmacokinetics*; D011874:Radiometry / Q000379:methods*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
D000336:Aerosols; D011868:Radioisotopes