Can inhalation of even one particle of plutonium result in cancer in humans?
Research has shown that a person would have to inhale large amounts of plutonium‐contaminated dust particles to have a significant radiation exposure. One study concludes that, “Based on our calculations, millions of dust particles contaminated with PuO2 (plutonium oxide) must be inhaled in order for significant radiation doses to be delivered to key body organs/tissues (bone surface, red marrow, lung, liver)”. (Scott, B.R., et al, 1999, Recommendations for improving the interim radionuclide soil action levels for the Rocky Flats Cleanup Agreement, Lovelace Respiratory Research Institute.) This conclusion is based on several multiple‐particle intake distributions generated for PuO2 from re‐suspended soil deposited in the respiratory tract. The mean intake of plutonium resulting from inhaling a certain number of contaminated dust particles from soils with a specific activity can be derived from these distributions. As an example, if someone breathed in a million dust particles from soil contaminated with plutonium at an activity level of 6.5 pCi/g (highest level measured off‐site), the average intake is predicted to be only about 2.4 x 10‐4 pCi (0.00024 pCi/g).
These distributions demonstrate that although it may be possible for smaller numbers of plutonium particles to induce cancer in some individuals, it is highly unlikely. So in theory, a single exposure could initiate the chain of events which lead to cancer, but exposures that induce cancer risks below one in a million are considered to be negligible.