Answer to Question #1379 Submitted to "Ask the Experts"

1. Chemical toxicity. Uranium is a heavy metal and, like lead, is toxic. In sufficient doses it can cause serious illness or even death within a short time. This effect is deterministic; that is, it occurs in every individual who gets a sufficient dose, and its severity is proportional to dose.
    
2. Uranium is radioactive. It emits alpha particles, which produce a dense pattern of ionization but over a very short range in tissue—little more than the thickness of a sheet of paper. In sufficient doses it can produce delayed effects. Cancer can occur years to decades later. Mutations can, in theory, be expressed in some future generation.

Both of these effects are stochastic in nature; that is, their probability of occurrence is proportional to dose. There is currently debate in the scientific literature regarding the possible presence of a threshold dose, below which these effects do not occur. It is not clear at this time whether this threshold exists; if it does, it is at a low level. Because of these effects, we should make all reasonable effort to eliminate uranium in the drinking water and food chain. This does not necessarily mean, however, that we should devote massive effort and money to elimination of a very low concentration. We could be ignoring more serious threats. S. Julian Gibbs, DDS, PhD