For folks living through the cold war, there were few precautions to take in the event of nuclear exchange: go underground, get out of town or at least run upwind. In the years since Chernobyl and Three Mile Island--and the months since Sept. 11--the advice has got a good deal more sophisticated. The safety measure generating the most buzz lately is potassium iodide--a widely available pill that, so the stories go, can help prevent people exposed to radioactivity from developing cancer. The stories are true--up to a point.
Nuclear detonations release a hail of charged particles, common among them radioactive iodine. This is bad news for the human thyroid, which soaks up iodine like a sponge. One way to prevent the problem is to dose the body with potassium iodide, which saturates the gland and prevents the nastier form of the stuff from being absorbed. It's simple--but of limited value. First, little if any iodine is given off by a so-called dirty bomb--radioactive waste wrapped around a conventional explosive--which is the device a terrorist would be most likely to manage. Second, even if radioactive iodine were present, potassium iodide would protect only against thyroid cancer--which is not the sole cancer risk.
Nonetheless, potassium iodide has had its successes. Following Chernobyl, which released a giant plume of radiation, the Polish government distributed tablets to the population, while neighboring Belarus didn't. Fifteen years later, the incidence of thyroid cancer has not changed in Poland, while it has jumped an alarming 100-fold among some Belarussian children. The U.S. Nuclear Regulatory Commission is now giving states the option of stocking up on potassium iodide for communities near the nation's 103 nuclear power plants. Still, the NRC emphasizes that the drug is not the next Cipro. Says NRC spokesman William Beecher: "It can protect only one part of the body against one radioactive element."
Meanwhile, the Pentagon is hoping to hasten federal approval of another drug, 5-androstenediol, an immune-system booster that appears to protect mice from radiation. Still another medication, amifostine, is already used to protect the salivary glands of cancer patients during radiation treatment and could find applications in the terror wars as well.
For all these pharmacological possibilities, there are other, more straightforward ways to reduce the danger from a nuclear or radioactive device. According to the Federal Emergency Management Agency, the three variables that determine the impact of radiation have not changed since the cold war: time, distance and shielding. After a nuclear device or dirty bomb goes off, survivors should quickly move away from ground zero and return home or to a safe place indoors--trying to stay uphill or upwind on the way. Once there, they should shower, change clothes and put all items worn outdoors in a sealed plastic bag. Pets should be brought inside; cracks around doorways and windows should be closed off with wet towels and duct tape; air conditioners and vents should be covered with plastic, waxed paper or aluminum foil and sealed with tape. Bathtubs and other containers should be filled with water and the pipes shut off, in case reservoirs become contaminated.
If authorities recommend evacuation, car windows and vents should be closed and a first-aid kit packed. FEMA provides more suggestions on its website, www.fema.gov. The advice may not be as appealing as a panacea pill, but to an increasingly jittery public, almost any advice is welcome.