DOMESTIC RADIATION

The potassium substitute (KCI) for salt (NaC1), used by people with high blood pressure to avoid sodium intake, will increase the potassium blood level, and hence the internal radiation dose, writes reader T.L.C. of Dallas, N.C.; he asks by how much.

About 1 out of 140 potassium atoms in nature is radioactive, whereas virtually all sodium atoms in nature are stable. However, even without salt substitute, the average human body contains 140 grams (5 oz) of potassium, to which 1/140^th of a little salt substitute is an insignificant addition.

Reader G.F.G. of Milwaukee, Wisc., asks about the safety of uranium oxide (used for color) in old pottery and dinnerware.

If you keep it ventilated (the uranium produces radon) and don't keep it constantly close to your body, it will be practically harmless, nowhere near as hazardous as an energy efficient home [AtE Jun 84]. A closely related "problem" is that of glass enamel frit used by jewelers to produce brightly colored surfaces. In a recent ruling (Fed. Reg. 30 Apr. 84, pp. 18308-9), the NRC deleted an exemption from licencing requirements formerly granted to glass enamel frit, because jewelry containing it could give the wearer a dose corresponding to a skin cancer incidence of 2 to 4 per million, and even then rarely lethal. This is typical of the overstrict, image-polishing rules of the NRC, which are out of all proportion with the radioactive doses people get in energy-efficient homes from the radon daughters [AtE Jun 84]. Not only is skin cancer a picnic compared to lung cancer, but the lifetime risk from radon daughters at the level where remedial action is recommended by the National Council of Radiation Protection (see June issue) corresponds to two deaths by lung cancer per 100,000 -- some 50 times more when the mortality is factored in. This level is often exceeded in American homes, but radioactivity in the home is not the NRC's department; that is EPA turf, and the EPA yawns over radon while it polishes its image with bunk about EDB (see "Good Reading.")