Spermicides may not offer HIV protection.

Risky sex just got riskier. A new study suggests that a common spermicide offers no protection against the AIDS virus (HIV).

Previous human trials had suggested that spermicide use helped ward off infection with disease-causing microbes such as Neisseria gonorrhoeae. Many researchers jumped to the conclusion that spermicides also offered a shield against HIV because nonoxynol 9, the active ingredient in most spermicides, kills HIV in the test tube.

Right now, the male condom represents the most reliable method (short of abstinence) of avoiding infection with sexually transmitted microbes. However, studies show that a number of men will not use this method. Some public health experts therefore recommend that women whose partners won't use condoms turn to spermicidal methods, such as a vaginal sponge that contains nonoxynol 9.

A new study suggests that such advice may prove premature. Joan Kreiss of the University of Washington in Seattle and her colleagues studied 138 prostitutes in Nairobi, Kenya, who tested negative for HIV infection at the study's start. The team randomly assigned 74 of the women to a group instructed to wear a sponge impregnated with nonoxynol 9. The remaining 64 used a placebo cream or suppository during sexual encounters. In addition, the researchers stressed to all women the importance of getting their partners to use condoms.

For more than a year, the research team followed these women, asking them to return to the clinic for periodic visits. During that time, 14 women in the nonoxynol 9 group and eight women in the placebo group dropped out of the study, leaving a total of 60 in the sponge group and 56 in the placebo group.

When the team analyzed their data, they found that the two groups were similar with respect to age and percentage of sex partners who used condoms.

Prostitutes using the nonoxynol 9 sponge reduced their risk of N gonorrhoeae infection by 60 percent, a finding that confirms previous data. However, the sponge failed as a guard against HIV.

"We were unable to demonstrate that nonoxynol 9 sponge use was effective in reducing the risk of HIV infection among highly exposed women," the authors report in the July 22/29 Journal of the American Medical Association. Their findings were also presented during a briefing at the VIII International Conference on AIDS in Amsterdam last week. The team discovered that 27 of the 60 women (45 percent) in the sponge group and 20 of the 56 women (36 percent) in the placebo group developed HIV antibodies during the course of the study.

In addition, sponge users had an increased risk of genital ulcers, a finding that suggests the sponges may actually increase the risk of HIV transmission, comments Katherine M. Stone, an epidemiologist at the Centers for Disease Control in Atlanta. Stone, who wrote an editorial accompanying the report, wonders whether the study's findings can be applied to women who are at lower risk of HIV infection. "The bottom line is the jury is still out on spermicides and HIV," Stone says.