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  • An independent laboratory showed high levels of benzene, a known carcinogen, in 70% of dry shampoo samples tested.
  • The amount of benzene in each shampoo varied across brands and different batches of products in the same brand.
  • Experts are concerned about consumer exposure to benzene because of both long-term and short-term negative effects of exposure.

A new report finds that a known carcinogen may be more common in dry shampoo than previously thought.

Valisure, an independent laboratory in New Haven, Connecticut, that tests and provides quality assurance checks on different products, analyzed 148 unique batches from 34 different brands of dry shampoo.

The analysis found high levels of benzene in 70% of dry shampoo samples tested. Benzene is a known carcinogen.

Studying dry shampoo samples

The amount of benzene in the samples varied significantly from batch to batch even in a single brand. Some samples from air contaminated with the sprayed product had up to 170 times the limit of 2 parts per million (ppm), set by the U.S. Food and Drug Administration (FDA). Eleven of these samples had over 10 times the limit.

Because of the high levels of benzene, Valisure is asking the FDA to recall contaminated dry shampoo batches and requesting the FDA to better define limits for benzene contamination in products like cosmetics.

What is benzene?

Benzene is a colorless chemical used mainly as a solvent.

The National Cancer Institute says that levels of benzene can be found in substances like cigarette smoke, adhesives, cleaning products, and paint strippers.

It can also be found in many petroleum products.

Petroleum products appear as inactive ingredients in consumer health and personal care products like dry shampoo.

How dangerous is using a dry shampoo with benzene?

co-medical director of the National Capital Poison Center in Washington, D.C., and the medical director of hyperbaric medicine at MedStar Georgetown University Hospital, said “Benzene is a known human carcinogen, and chronic exposure to benzene is associated with development of certain leukemias and other cancers. Short-term exposures to benzene can also cause drowsiness, headache, nausea, and other undesirable symptoms.”

Johnson-Arbor said the results of Valisure’s testing are “concerning because inhalation of benzene can cause both acute and chronic health issues” because “in some cases, the concentrations of benzene in the dry shampoo testing were quite high.”

Samantha Radford, a PhD chemist and public health expert writes the blog Evidence-Based Mommy, and cited what the American Petroleum Institute stated in 1948, that “the only absolutely safe concentration for benzene is zero.”

“People occupationally exposed to air containing only 1 ppm benzene have increased health risks,” Radford said. “With that said, working in a plant for 8-12 hours per day being exposed to benzene is very different than a few-second burst of exposure from a can of dry shampoo. It’s hard to say just how dangerous it is to use dry shampoo that is contaminated with benzene.”

Dry shampoo is a cosmetic product, which subjects it to FDA regulations. But unlike medications, the FDA does not approve cosmetic ingredients.

Instead, the agency has regulations around cosmetics but these are far more lax than for medications. As a result, most cosmetic ingredients are not vetted for safety through rigorous studies and human trials the way medications are.

Should you get rid of your dry shampoo?

Dr. Susan Massick, a board-certified dermatologist at The Ohio State University Wexner Medical Center, says, “The concern for benzene is that this is a potential carcinogenic with chronic exposure or in high concentrations. The likelihood of either type of exposure is low in a product that is localized to the scalp, but if it’s found in a product, it’s appropriate to recall, re-evaluate the manufacturing process, and test to make sure there are no ongoing manufacturing issues.”

Johnson-Arbor says, “Until the FDA recalls them, consumers should try to use dry shampoos as safely as possible, including applying them sparingly and only when needed, using them in well-ventilated areas, and not intentionally breathing in the product fumes.”

The experts offer differing advice on how to safely choose a dry shampoo but agree contamination is the likely culprit for the benzene.

Massick suggests “making sure the products are not on the recalled list.”

She also suggests avoiding aerosolized dry shampoo products because “the aerosolized products tend to be a common culprit.”

She points out a similar issue with aerosolized sunscreens where the ingredients themselves were not carcinogenic but traces of benzene were found.

Johnson-Arbor says, “It may be difficult to pick a ‘safe’ dry shampoo right now.”