Dose coefficients (organ-specific equivalent doses per unit activity of radionuclides inhaled)
• Dose coefficients for respirable particles (AMAD, 1 μm) often are higher than values for same particle size currently recommended for workers by ICRP.
• Dose coefficients for large particles (AMAD, 20 μm) often are higher than values based on current ICRP recommendations.
• Assumption of respirable particles overestimates dose to lung and many other organs when most inhaled materials are large particles.b
• Assumed absorption of refractory radionuclides (for example, plutonium and isotopes of yttrium, zirconium, and rare-earth elements) from respiratory or GI tract may be overestimated, especially when large particles are inhaled.
• Dose to respiratory and GI tracts may be overestimated when large particles containing alpha-emitting refractory radionuclides (for example, plutonium) are inhaled.
• Use of 50-year committed doses may overestimate relevant doses from intakes of long-lived radionuclides that are tenaciously retained in the body (for example, plutonium).c
• Dose coefficients for the lung may overestimate dose to tissues in respiratory tract where lung cancers occur.d