Does mean lung dose calculated after inhalation of alpha emitters actually reflect the risk of induction of malignant lung tumours?
A comparison of incidence of lung tumours in rats after inhalation exposure to aerosols containing alpha emitters which have different physico-chemical properties has been performed. Aerosols of radon and progeny, uranium ore dust, NpO2, PuO2 or Cm2O3 were considered for intercomparison with similar or different particle sizes. Dose-effect relationships for the frequency of malignant lung tumours appear linear up to a few Gy and then become infralinear at higher doses delivered to the lungs. The initial slope of the curves reflects the risk of induction of a lung tumour. The highest slopes of incidence were observed for radon and uranium ore dust (about 70 and 20% Gy(-1) respectively) for which the most homogeneous alpha dose distribution to the lungs is expected. In a general trend, increasing the alpha-activity of deposited particles (higher specific activity of constituent radioisotopes or larger particle size) decreases the risk. The comparison of the reported data shows that the risk per Gy at 'low doses' could vary over more than one order of magnitude depending on the physico-chemical properties of the aerosols.
Fritsch
P
P
Laboratoire de Radiotoxicologie, CEA/DSV/DRR, BP 12, 91680 Bruyères le Châtel, France. paul.fritsch@cea.fr
Dudoignon
N
N
Guillet
K
K
Oghiso
Y
Y
Morlier
J P
JP
Monchaux
G
G
D008671:Actinoid Series Elements / Q000008:administration & dosage / Q000633:toxicity*; D000280:Administration, Inhalation; D000396:Air Pollutants, Radioactive / Q000633:toxicity*; D000512:Alpha Particles; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D019570:Inhalation Exposure; D008175:Lung Neoplasms / Q000209:etiology*; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D011829:Radiation Dosage; D011868:Radioisotopes / Q000008:administration & dosage / Q000633:toxicity; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018570:Risk Assessment / Q000379:methods*
D008671:Actinoid Series Elements; D000396:Air Pollutants, Radioactive; D011868:Radioisotopes