THE HIDDEN DANGER OF MANTLE LAMPS

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At any rate, what struck Wagner about the incident was that the mantle registered on the scintillation counter he'd brought along on the tour. He was surprised, because thorium is an alpha-emitter, and most such particles should have been stopped by the packaging. Reflecting on it later, Wagner decided that the counter was not registering thorium at all, but—instead—indicating the presence of some of its decay elements . . . so he bought a mantle to experiment with.

After confirming his theory, Walt contacted the Coleman Company in March 1981 to ask the firm to put warnings on mantle packages. When that effort proved unsuccessful, Wagner filed a $300 million class action suit, in November 1981, against the Coleman Company and other manufacturers of mantles . . . which seeks to return reputed damages to mantle purchasers and to require the companies to begin using warning labels on their products.

THORIUM AND HEALTH RISKS

By way of a little background, the thorium (Th-232) that's used in lanterns is a fertile nuclide, which can actually be bred into uranium 233 (U-233), a fissionable isotope suitable for nuclear weapons or reactors. (In fact, thorium itself has been used in reactors on an experimental basis and supposedly could have been bred into weapons-grade U-233 at the Osirak nuclear power plant located near Baghdad, Iraq, which was de stroyed by the Israelis on June 7, 1981.)

In a home or tent, the main danger in mantle use arises from thorium's first radiodaughter, radium 228 (Ra-228). Radium is a "bone seeker" . . . which means that it is biochemically analogous to calcium, and that the body will substitute it for calcium during periods of bone growth. Thus, the radiumladen fumes from lamp mantles present an obvious hazard to children who may be close by. Likewise, pregnant women and their unborn babies—could be endangered, since Ra-228 (and Ra-224), which can be inhaled and ingested by the mother, readily crosses the placental barrier and can be absorbed by the fetus. Similarly, a nursing mother who inhales volatized radium would pass some of it along to her infant.

TAKING PRECAUTIONS

While the chief sources of danger are the alpha-particle-emitting daughters of Ra-228, Wagner says that "significant" beta radiation can strike the body when a mantle is placed close to the skin. If it's carried in a shirt pocket, for instance, the breast and lung tissue will absorb radiation . . . and if it's put in a pants pocket, a man's testicles would be exposed to some low-level radiation (though the actual risk involved in either case is, at present, subject to debate). Wagner cautions that a mantle—even when it's new and still inside its packaging—should never be placed in pockets, and children should never be allowed to touch or play with the devices.

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