Tincture of iodine keeps radiation away.

Researchers at Pennsylvania State University's medical center in Hershey have stumbled onto what may be an effective home remedy to prevent serious radioactive contamination of the thyroid gland from iodine-131 emitted in the event of a major nuclear plant mishap. They swab the skin with a tincture of iodine.

Of the many radioactive gases that can be emitted during a nuclear plant release, iodine-131 causes special concern. Because iodine is readily accumulated in the thyroid, exposure to radioactive iodine can lead to serious, concentrated doses in the small metabolism-regulating gland. For years scientists have considered prescribing community-wide ingestion of potassium iodide in regions downwind of a serious nuclear accident to block the thyroid's uptake of radioactive iodine.

The body can't distinguish between radioactive iodine and the iodine in the drug, so taking potassium iodide would fulfill the thyroid's need for the element. Should any radioactive iodine be inhaled or ingested later, studies show most of it would be excreted. This would prevent the radioactive damage -- including thyroid cancer--it might otherwise have initiated.

But potassium iodide is prescription drug, and its post-accident distribution could exacerbate the traffic tie-ups and panic that nuclear crises would inevitably foster. In fact, says Kenneth Miller, director of health physics at the Hershey Medical Center, his team's decision to look at skin absorption of household iodine sources resulted from discussions over how they would have tried to manage potassium iodide's distribution in the immediate hours after the neighboring Three Mile Island accident in 1979.

In their study, the Hershey team injected 2 microcuries of iodine-131 into 72 rats. Haft got no further treatment; the others were treated with one of the following: a paw dipped in tincture of iodine or povidone iodine (an over-the-counter germicidal solution), skin swabbing with tincture of iodine (some with a covering bandage) or oral administration of potassium iodide. Writing in the November HEALTH PHYSICS, Miller and his colleagues report that all skin applications of household iodine solutions were comparable to oral potassium iodide in blocking thyroid uptake of iodine-131; they limited the gland's accumulation to between 3 and 10 percent.

While cautioning that these were animal studies, Miller told SCIENCE NEWS, "We think there is a failry good possiblity that this technique will aslo work in humans." Moreover, since these skin compounds are approved for human use, and since the effective dose in rats suggests human skin swabbing need only cover an area the size of a hand or scraped knee, Miller sees little concern over safety. His team is now preparing to conduct the necessary human tests.