Who knew that the key to preventing cervical cancer could be as simple as table vinegar?

In a method developed by experts at Johns Hopkins medical school and recently endorsed by the World Health Organization, clinic nurses around the world are being trained to use a solution of table vinegar — 5 percent acetic acid — to detect cancer.

By brushing it directly onto the cervix, nurses can see within three to five minutes whether any precancerous lesions exist, because the vinegar turns them white. The lesions can then be frozen off during the same visit using a metal rod cooled by a tank of carbon dioxide.

"One of the amazing things about this inspection: precancerous lesions of the cervix are fairly obvious. A nurse trained for three or four days will be able to see it with her naked eye,” said Dr. Ricky Lu, a cervical cancer prevention expert who works with the organization Jhpiego, a global health affiliate of Johns Hopkins University, in an interview with Healthland this month. "Even with people who are medically untrained, it’s not difficult to see.”

The cheap and easy screening test has been employed in pilot projects in more than 20 countries, including Ghana and Zimbabwe.

Although doctors in rich nations can rely on regular Pap smears to monitor women’s cervical health, health-care workers in developing countries, many of whom work in remote regions and don’t have access to reliable labs, don’t have the same luxury.

As the New York Times’ Donald G. McNeil Jr. reported in a big feature on Tuesday, the vinegar method has the "potential to do for poor countries what the Pap smear did for rich ones: end cervical cancer’s reign as the No. 1 cancer killer of women.”

Of the more than 250,000 women who die of cervical cancer each year, 85% of them are from poor- and middle-income countries, McNeil reported. In the U.S., meanwhile, cervical cancer now kills far fewer women than cancers of the lung, breast, colon and skin.

How does the vinegar test — known as VIA/cryo, for visualization of the cervix with acetic acid and treatment with cryotherapy — work? According to the Times:

Dr. Bandit Chumworathayi, a gynecologist at Khon Kaen University who helped run the first Thai study of VIA/cryo, explains that vinegar highlights the tumors because they have more DNA, and thus more protein and less water, than other tissue.

It reveals pre-tumors with more accuracy than a typical Pap smear. But it also has more false positives — spots that turn pale but are not malignant. As a result, some women get unnecessary cryotherapy.

But freezing is about 90 percent effective, and the main side effect is a burning sensation that fades in a day or two.

In Thailand, VIA/cryo has been adopted as routine practice in 29 of 75 provinces, the Times reports. The country is ideal for the program because it has more than 100,000 nurses who largely help run a network of clinics in rural areas. Whether VIA/cryo will help lower the cancer rate in Thailand, however, it’s too soon to say.

TIME