Dry shampoo and cancer risk: What you need to know

Many people use dry shampoo in their normal routine, stretching the days between washing their hair in the shower. In October of last year, the Food and Drug Administration found potentially elevated levels of benzene, a carcinogen, or cancer-causing chemical, in these products. Popular brands of dry shampoo are under a voluntary recall of products manufactured before October 2021 because they contained benzene.

The dry shampoo recall may have removed concerning products off store shelves, but it's important to make sure they aren't still stored at home. "It's less of a concern that stores haven't pulled the shampoos from their shelves, but more of a concern that someone has bought it and it's sitting at home in the cabinet," says Britton Trabert, Ph.D., MS, epidemiologist at Huntsman Cancer Institute and assistant professor of obstetrics and gynecology at the University of Utah (the U). "It would be good to check the product name, lot number, and UPC code of your dry shampoos that you have stored and get rid of ones that contain benzene."

The National Cancer Institute (NCI) describes benzene as a room temperature, colorless or light-yellow liquid chemical. People can be exposed by breathing air containing the chemical, skin, or orally. It has been linked to leukemia and other blood cancers, according to NCI.

"Most of our understanding about benzene as a human carcinogen comes from individuals who have had long-term exposure to high levels of benzene, like chemical manufacturing workers that use or make benzene," says Steven Lacey, Ph.D., MS, professor and division chief of public health at the U.

"Less is known about the risk from comparatively lower exposures from consumer products, but once this type of product contamination is known, it seems easy enough to avoid, especially when so many alternatives exist—in this case, newer versions of dry shampoos that don't contain the chemical. The voluntary recalls we have seen by manufacturers seem prudent until consumer exposure is better understood, or product formulation is changed."

A carcinogen is a substance that can change the way our cells function, causing cancer. Although, just because something is labeled a carcinogen, exposure doesn't always result in cancer. Risk of developing cancer depends on length of exposure and genetic background. NCI gives a list of known carcinogens.

"Since 1979, benzene has been considered carcinogenic to humans by the International Agency for Research on Cancer (IARC)," says Rodney Handy, MBA, Ph.D., professor of family and preventive medicine at the U. "The American Conference of Governmental Industrial Hygienists classifies benzene as a class A1 confirmed human carcinogen, targeting the blood with exposures leading to leukemia."

When the dry shampoo is sprayed, the petroleum-based propellent ingredients, or gas that turns to liquid under pressure of an aluminum aerosol can, contains trace amount of benzene.

"If you have been using the dry shampoos listed in the recall by the FDA before they were pulled from shelves, I would communicate that with your doctor," says Trabert. "You can have a conversation with your doctor about what would be appropriate for monitoring potential health effects, and your doctor will be aware of what tests they need to order if there are concerns."