Inhalation Hazards in Nuclear Energy Programs

Stable Elements

¹ Institute of Industrial Health and Department of Pathology, University of Michigan, Ann Arbor.

1. The military and peacetime nuclear energy programs have greatly expanded the potential scope of human exposures to new and old dust, fume, and gaseous environmental hazards. A large proportion of these new dangers may originate in the biological action of stable elements rather than radioactivity.

2. Exposures are possible in the operations of assembling raw materials, during the processes of extracting, refining, and chemically modifying the various key elements, and in the manufacture of thermonuclear weapons and peacetime reactors.

3. Among the various stable elements, to which exposures are likely, beryllium has the worst record as an inhalation hazard, and this is unfortunate as its strategic nature has greatly increased its use. While some of the newly introduced elements are highly dangerous, a gratifying number appear to be entirely inert. Many of the lesions which may occur in exposed personnel undergo spontaneous remission.

4. Practically all hazards should be preventable by appropriate engineering methods.

5. Various characteristic pulmonary lesions are discussed. Among these the local accumulation of foreign particles, focal fibrosis, cellular and stromal necrosis, chronic macrophage catarrh, epithelialization of alveolar walls, granuloma formation, and vascular damage are the most spectacular.

6. Many of the lesions observed in man have been experimentally reproduced. It has also been possible to induce pulmonary cancer in rats through exposures to various compounds of beryllium even at very low dosage levels.

7. Problems still to be solved, besides methodical, experimental and clinical exploration of the full range of substances to which human beings may be exposed, are: threshold levels of toxicity, especially in connection with prolonged exposures; differential responses in animal species and their applicability to man; precise diagnostic criteria, particularly in life; medico-legal difficulties created by the delayed occurrence of disease after exposure and the national importance of the nuclear energy program; antidotal and therapeutic agents. Only further research can furnish the necessary answers.