(FORTUNE Magazine) – When the Surgeon General endorsed condoms as a means of preventing the spread of AIDS, sales soared. Now makers of spermicides containing nonoxynol 9 may be in for similar increases. Reason: Recent findings show the chemical to be effective in killing the AIDS virus before it enters the blood. At GAF, America's largest supplier of government-approved nonoxynol 9 to pharmaceutical companies and condom makers, sales of the chemical have doubled in a year. % Condoms treated with nonoxynol 9 account for 20% of the $250-million-a-year U.S. condom industry, up from nothing in five years, and demand could easily increase that proportion. Researchers from the National Institutes of Health found that women who used spermicides containing nonoxynol 9 reduced their chances of getting gonorrhea by 60%. That is especially important: Contracting sexually transmitted diseases increases a person's susceptiblity to AIDS. - C.G.