In Brief

ALL CHOKED UP Offering the strongest evidence to date, a study of half a million people in 116 cities shows that long-term exposure to tiny soot particles from coal-burning power plants and diesel engines raises the risk of lung cancer some 20%--comparable to the effect of living with a smoker. What can you do? Try air filters--or get out of town.

SEX AND THE CITY The U.S. government reports that the rate of gonorrhea infections nationwide finally leveled off in 2000. That's the good news. The bad? It shot up more than 20% in cities like Buffalo, N.Y.; Jacksonville, Fla.; Detroit; Nashville, Tenn.; and Kansas City, Mo. The best way to prevent the sexually transmitted disease is abstinence or condoms. But don't count on help from the spermicide nonoxynol-9. Contrary to expectations, a separate report shows that nonoxynol-9 does nothing to kill off gonorrhea bacteria.

REPAIR KIT In a scientific first, researchers report that adult stem cells circulating in the bloodstream don't just regenerate the blood supply; they can also morph into skin, liver and intestinal tissue. What's the significance? The news suggests that the body may have a stash of universal repair cells, capable of being dispatched to wherever they are needed--and which someday may be used to treat disease without having to rely on the controversial stem cells taken from human embryos.

Sources: J.A.M.A.; Centers for Disease Control and Prevention; New England Journal of Medicine