Newswise — In March, the U.S. Food and Drug Administration (FDA) announced voluntary recalls of several popular acne products due to contamination with benzene, a known cancer-causing chemical.
The FDA was prompted to conduct its own testing after receiving a report from Valisure, an independent drug quality control testing laboratory based in New Haven, Conn., highlighting concerns about the safety of certain topical products containing the active ingredient benzoyl peroxide (BPO). BPO is a chemical commonly used in acne products for killing the bacteria that is associated with breakouts and inflammation. However, over time, it can break down into the carcinogen benzene, researchers have found.
The Valisure team tested the stability of a variety of acne products containing BPO. They discovered that many violated the conditional FDA limit of two parts per million (ppm), with some containing levels as high as 35 ppm. They published their initial findings in Environmental Health Perspectives in March 2024, and a follow-up study in the Journal of Investigative Dermatology in October 2024.
Benzene is in your acne products, it’s in your dry shampoos, it’s in your sunscreens, it’s in second-hand or direct cigarette smoke, it’s in exhaust from cars. It’s all the benzene exposure throughout all of society that adds cumulative risk. And the last place consumers need additional risk is in an acne product.
The voluntarily recalled products were La Roche-Posay Effaclar Duo Dual Action Acne Treatment, Walgreens Acne Control Cleanser, Proactiv Emergency Blemish Relief Cream Benzol Peroxide 5%, Proactiv Skin Smoothing Exfoliator, SLMD Benzoyl Peroxide Acne Lotion, and Walgreens Tinted Acne Treatment Cream.
“There shouldn’t be any carcinogens in any of our acne products,” says Christopher Bunick, MD, PhD, associate professor of dermatology and translational biomedicine at Yale School of Medicine, who is a co-author on both of the studies. Bunick collaborated with Valisure as an independent scientific consultant and did not receive compensation from the company. “The recall is a victory for patient safety,” he adds.
What is benzoyl peroxide?
BPO treats acne by killing bacteria such as Cutibacterium acnes that contribute to the condition. Some dermatologists believe that BPO also has a direct anti-inflammatory effect, and that it helps prevent pores from becoming clogged. “Benzoyl peroxide has been incorporated in acne products for a very long time because it has multiple ways that it can target the pathogenesis of acne formation,” says Bunick.
When combined with topical antibiotics, BPO can help reduce the risk of antibiotic resistance. The use of widely used antibiotics such as clindamycin to treat acne alone has contributed to the rise of resistant strains of acne-causing bacteria; any bacteria able to survive the antibiotic will reproduce, leading to strains not susceptible to the antibiotic at all. Many products available today combine BPO with antibiotics to boost bacterial killing power and wipe out any mutated bacteria before they can multiply.
Before its dermatological applications, BPO’s use dates back a century when companies utilized it as a plasticizer. Even back then, scientists recognized the instability of the chemical and its potential hazards to human health. As early as 1936, German-Swiss chemist Hans Erlenmeyer described the breakdown of benzoyl peroxide into the carcinogen benzene. Flash-forward several decades—in 1997, the manufacturing company AkzoNobel filed a patent for reducing benzene formation.
Researchers find benzene contamination in acne products
Valisure was founded by a team of Yale entrepreneurs in 2015 to conduct independent testing on the safety of pharmaceutical and consumer products. Since its launch, it has submitted eight FDA Citizen Petitions—a process for requesting the FDA to make regulatory changes—after discovering the presence of carcinogens in various products, including blood pressure drug valsartan, type 2 diabetes drug metformin, and heart burn drug ranitidine (Zantac). All eight of these petitions have led to a product recall.
Over the last several years, the private company has identified a troubling trend—many commonly used dermatological products are contaminated with benzene. These have included hand sanitizers, sunscreens, aerosol sprays, and dry shampoos. “A lot of the precursors that go into forming these products actually are contaminated with benzene,” says Bunick. “A lot of these products become contaminated during the manufacturing process.”
Benzene contamination can have devastating health consequences. Epidemiological studies, for example, have shown that even trace levels can cause a substantially increased risk of leukemia. The researchers were especially concerned about finding the carcinogen in so many products that are put directly on the skin.
Following these findings, in December 2023, the FDA issued new guidance that called for the reformulation of certain drug products containing gelling agents called carbomers due to high levels of benzene contamination.
Then, in March 2024, the Environmental Health Perspectives study raised concern about a new group of products: acne treatments. The study investigated 66 BPO-containing over-the-counter and prescription products. By exposing the products to elevated temperatures, which simulates how they break down over time or under certain storage conditions, researchers discovered that they became contaminated with benzene.
Our analyses found that there were varying levels of benzene in different consumer products that were above the FDA guidelines.
The researchers also sent their samples to three independent laboratories, including at Yale University’s Chemical and Biophysical Instrumentation Center (CBIC). The laboratories confirmed that these products had elevated levels of benzene. “Valisure approached us and asked us for help as a secondary testing laboratory for validating their results,” says Fabian Menges, PhD, mass spectrometrist at CBIC. “Our analyses found that there were varying levels of benzene in different consumer products that were above the FDA guidelines.”
Unlike other products, the benzene in acne medications stems not from contamination during the manufacturing process, but from the breakdown of the active ingredient, BPO, itself. Valisure coupled this study with an FDA citizen petition, which urged the agency to once again take action.
Several months later, the team published a follow-up study in the Journal of Investigative Dermatology. This time, in response to some criticism of the high temperatures used in their initial stability testing, they tested 111 products for benzene at room temperature. “We tested the products right off the shelf—that any consumer can walk into a store and buy,” Bunick says.
One in three products, they found, violated the conditional FDA limit of two ppm. A conditional limit only applies to products that have a substantial therapeutic advance and there are no other ways to make the product. For everything else, there is no acceptable amount of benzene. “Every large store in America that has these products likely sells at least three benzoyl peroxide medications a day,” Bunick says. “That means at least one person per large store per day is walking out the door with a product containing a carcinogen level above the FDA regulatory limit.”
These findings prompted the FDA to conduct its own testing of BPO-containing acne products. While their results showed fewer products contaminated with benzene, the testing led to its voluntary recall of six popular acne treatments. The study highlights the importance of complementing FDA regulatory processes with independent analyses for uncovering drug quality issues that may have been otherwise overlooked, the researchers say.
Valisure findings face criticism
Some critics have questioned Valisure’s testing protocols and claim that the company’s findings overstate the risk of benzene contamination in acne products. Others like Bunick, on the other hand, believe that the FDA’s announcement understates the significance of the problem. Regardless, the FDA recall validates the concern raised by Valisure’s Citizen Petition about benzene contamination and that steps need to be taken to fix this issue. “The fact that there were recalls at all shows that the problem is real,” Bunick says.
One reason that the FDA may have identified less benzene contamination than Valisure, Bunick explains, may be because there was a significant amount of time between Valisure’s initial announcement and the FDA’s own testing. “The products that the FDA tested may not necessarily have been the same products that Valisure was testing,” Bunick says. “Companies had time to go back and assess their manufacturing and quality control processes, and fix potential problems.”
What does benzene contamination mean for public health?
Because there are many other ways to treat acne that do not involve benzoyl peroxide, there is no acceptable level of benzene in acne products, the researchers say. For example, Valisure’s analyses of other acne products including salicyclic acid and adapalene did not find any benzene contamination.
And even if the concentration of benzene in many acne products is low, the chemical’s pervasiveness elevates its risk to public health. “Many people are saying that a lot of these products have less than two parts per million, so the risk is not that significant,” says Bunick. “But wait—benzene is in your acne products, it’s in your dry shampoos, it’s in your sunscreens, it’s in second-hand or direct cigarette smoke, it’s in exhaust from cars. It’s all the benzene exposure throughout all of society that adds cumulative risk. And the last place consumers need additional risk is in an acne product.”
Because it can take years from the initial benzene exposure to see its health impact, the effects of benzene contamination in dermatological products are still not well understood. “When you get a sunburn as a kid, that can mean that 50 years later you get skin cancer from that sunburn,” Bunick explains. “When you have chemicals like benzene that are carcinogens, that same lag time applies—it can be decades before you have a consequence from that exposure.”
Bunick recently collaborated with researchers at the University of Calgary on a pharmacovigilance study—or a study that monitors the safety of medicines after they have been approved for public use—on BPO-containing acne products. Using the FDA Adverse Event Reporting System (FAERS) database, they conducted a disproportionality analysis, which investigates whether the odds of an adverse event for a certain type of drug is higher in comparison to other drugs.
The analysis revealed that BPO-containing products were associated with greater odds of users reporting skin and breast cancer. The FAERS study showed one brand had the highest odds of reports, which is consistent with that brand also being one of the worst offenders in the Valisure study.
While useful for identifying statistical signals, FAERS is a passive surveillance system that cannot establish incidence rates or causality and may reflect reporting bias. Rather, it is a “hypothesis-generating” study, says Bunick. “The study gives us a clue that there may be a problem,” he explains.
“Although we can’t definitively say there is a causality, we can say this matter needs closer investigation and it highlights the need for comprehensive safety evaluation of products that contain benzoyl peroxide,” adds Fatemah Jafarian, MD, associate professor of dermatology at the University of Calgary and the study’s principal investigator.
The study emphasizes the need for future epidemiological research. “The story is not closed,” says Bunick. “Understanding the health risk of benzene contamination is still needed, and it’s really important for us to be thinking forward about what to do next.”
What to do if you use a BPO-containing product
In the meantime, the FDA’s voluntary recall is an important measure for reducing this exposure and protecting public health, the researchers say. “I think it’s a good start,” says Jafarian. “I’m really looking forward to seeing the FDA’s data and testing methods for the recalled products that they have stated they will publish in the near future.”
Users of BPO-containing acne products don’t necessarily need to throw them in the trash, the researchers say. Consumers can take steps to protect themselves, including using the product before its expiration date and avoiding storing these products in hot environments such as in the shower or near a heat radiator.
“Don’t panic. Benzoyl peroxide in most cases can still be used safely with proper precautions,” says Jafarian. “It’s important that you talk to your dermatologist if you have a concern and discuss your medication’s risk and benefits.”
