Benzene 101: The Cancer-Causing Agent That Keeps Showing up in Beauty

Benzene 101: The Cancer-Causing Agent That Keeps Showing up in Beauty featured image
Tanja Ivanova / Getty Images

Another day, another ingredient to be on the lookout for in our beauty products. According to third-party testers, Valisure, benzene has been found in several acne-fighting products. But this time, the problem is a little more complex than just avoiding formulas that contain it.

The chemical processes at play once the product is out of the formulation stage also matter. That means where and how a product is stored can cause benzene to form, given the right conditions.

That’s how acne products containing the common zit-fighter benzyl peroxide were found to have benzene in them. The chemical was created when these products were stored in hot environments. And not just a warm shower-level.

“We’re talking about temperatures upwards of 100 degrees Fahrenheit,” says Montclair, NJ dermatologist Jeanine Downie, MD. “This is a chemical reaction that’s occurring because of improper storage conditions; it’s not like anyone is sprinkling this cancer-causing agent on top of their formulas. It’s a breakdown.”

  • Jeanine Downie is a board-certified dermatologist based in Montclair, NJ
  • Victoria Fu & Gloria Lu are cosmetic chemists and founders of skincare brand Chemist Confessions

What Is Benzene?

Sweet-smelling, colorless and very dangerous, benzene is a commonly used chemical that’s classified as as a group one carcinogen. It’s also all around us.

“Benzene is a chemical compound that is liquid at room temperature and evaporates very quickly,” explains cosmetic chemist Victoria Fu. “It is found in petroleum products as well as coal. It is used as a solvent in certain manufacturing processes. It’s a common trace byproduct of combustion, so there are trace amounts of benzene in the air from industrial processes, car exhaust, burning wood, cigarette smoke, etc.”

While its use has been pulled back in recent years, according to the CDC, benzene is still used in some industries to create other chemicals that are used in the creation of dyes, plastics and resins. These days, the ingredient is regulated and must stay below certain levels in products like gasoline. In the U.S., benzene is banned as an ingredient in products intended for the home.

“It’s classified as a carcinogen that with enough exposure can increase the risk of developing leukemia and other blood disorders,” says cosmetic chemist Gloria Lu.

How are we usually exposed?

Normally, exposure comes from inhalation, according to the American Cancer Society. Human activity makes up for a lot of that exposure, and has devastating consequences.

In 2013, a study published in Cancer, the American Cancer Society’s journal, demonstrated that rates of non-Hodgkin lymphoma and benzene release sites were connected. “Our study is the first to examine the relationship between passive benzene exposure and the incidence of non-Hodgkin lymphoma at the state population level,” said Catherine Bulka, a research analyst at Vanderbilt University Medical Center. The study found incidence of non-Hodgkin lymphoma was significantly greater than expected surrounding benzene release sites.

According to the American Cancer Society, about half of the exposure to benzene in the United States comes from cigarette smoke.

Benzene and Beauty

So, how is it ending up in our beauty?

Well, the study from Valisure was definitely alarming. But benzoyl peroxide doesn’t become benzene until 158–176 degrees Fahrenheit.

“Incubation of a Proactiv product at the temperature of a hot car (70°C) resulted in the detection of benzene in a compact car’s volume of air at ~1,270 times the Environmental Protection Agency’s (“EPA”) calculated threshold for increased cancer risk by long-term inhalation exposure to benzene,” claims Valisure’s press release.

In case you needed to look it up (like I did), 70°C is 158°F. According to the CDC, a car in the sun is significantly higher than the ambient temperature, with recorded temperatures often surpassing 120°F.

“We have to ask if the testing process was entirely fair,” Dr. Downie says. “Is it a fair look at how these products are regularly stored?”

“We don’t find these results particularly alarming because the results actually come from exposing the BPO products to very high heat for weeks,” Fu explans. “These conditions aren’t very reflective of potential real-life conditions unless BPO is actually left in a hot car in Arizona for several weeks.”

If you’re buying a product in-store and taking it home, putting it on your bathroom counter and using it, you probably aren’t in any danger of coming into contact with benzene.

“Stores and pharmacies are liable for the condition of the product when you purchase it,” Dr. Downie explains. “But when you buy something online, it’s a lot harder to be sure. There’s no danger to buying toilet paper online and it being stored or shipped in very hot environments; it’s just toilet paper. But skin-care products are a different story.”

Dry Shampoos and Sprays

In 2021, P&G performed as voluntary recall after detecting trace levels of benzene.

“Following recent reports that indicated traces of benzene in some aerosol spray products, we began a review of our total portfolio of aerosol products,” P&G explains. “While benzene is not an ingredient in any of our products, our review showed that unexpected levels of benzene came from the propellant that sprays the product out of the can. We detected benzene in aerosol dry shampoo spray products and aerosol dry conditioner spray products.”


Also in 2021, researchers noticed benzene showing up during routine testing of sunscreen sprays.

According to the Cleveland Health Clinic, it wasn’t immediately clear how the benzene got there. “The theory being tested is that certain compounds present in spray propellants may mix to form benzene,” the clinic’s press coverage explains.

“Benzene is actually never used in the production or formulation of these products,” Lu clarifies. “However, it appeared that certain production batches were contaminated and then subsequently recalled.”

How to avoid it

Summers are certainly brutal in parts of the country, and if your days are frequently well above 100°F, it’s worth saying that you should not keep any product containing benzoyl peroxide in a hot car. That includes how the product you bought online is shipped to you.

“We know that some shipping companies air condition their trucks, but some, like UPS, do not,” Dr. Downie explains. “And you should not put something that’s been in a hot car environment on your face.”

Buying online from an unknown retailer (like third-party Amazon resellers) presents those kind of risks.

“If you’re seeing something online for a steep discount, it very well could be expired,” Dr. Downie says. “You should be skeptical of online purchases the same way you would be if you found a Gucci bag for half-off. Ask yourself: Is this a fake?”

That said, there’s no smoking gun ingredient to be on the lookout for.

“We believe there is no reason to actively avoid certain ingredients because of a fear of benzene,” says Fu. “Both of the previous benzene incidences are abnormal situations. For benzoyl peroxide specifically, the only precaution that could be taken is to simply not leave your BPO products in extreme temperatures (50-70C).”

Related Posts

Find a Doctor

Find a NewBeauty "Top Beauty Doctor" Near you

Give the Gift of Luxury

NewBeauty uses cookies for various reasons, including to analyze and improve its content and advertising. Please review our Privacy Policy and Terms of Use for more about how we use this data. By continuing to use this site, you agree to these policies.