Information now available on the question of lung irradiation from particulate plutonium is reviewed. Careful consideration of the available data shows that particulate plutonium is not more hazardous than the same amount of plutonium distributed uniformly. The data also suggest that the potential hazard from plutonium increases as the dispersion throughout the lung becomes more uniform. (CH)

Current status of the plutonium hot-particle problem

Single large radioactive particles are not carcinogenic in the lung. Plutonium dioxide is not the most toxic chemical compound known. About a million grams of plutonium have been initially entrained in the air from nuclear weapon testing. An initial inhaled concentration of >100,000 submicron diameter 239-plutonium dioxide particles per gram lung are associated with formation of large particle aggregates in the lung, giving a threshold dose to the lung of about 1 Gy for lung tumor development in rats, dogs and humans. Evidence of radiation hormesis has been found in animals and plutonium workers. A nuclear technician accidentally exposed to americium, delivering enormous radiation doses to the lung, liver and skeleton, died eleven years later at the age of 75 without any evidence of cancer. USTUR participants lived ten years longer than those not exposed to high levels of transuranics.

Charles L. Sanders

Papers

Plutonium Particle Toxicity Myth