Two new studies focusing on the safety of benzoyl peroxide (BP)–containing acne products with typical everyday use found no reason for concern about either high blood levels of benzene, a breakdown product of BP, or cancer risk.
Earlier this year, controversy erupted after an independent lab Valisure petitioned the US Food and Drug Administration (FDA) to recall acne products with BP because it found extremely high levels of the carcinogen benzene. In the research, the lab directors contended that the products can form over 800 times the "conditionally restricted" FDA concentration limit of 2 parts per million (ppm) of benzene, with both prescription and over-the-counter (OTC) products affected. The issue, according to the lab's report, is one of degradation, not contamination; BP can decompose into benzene. Exposures to benzene have been linked with a higher risk for leukemia and other blood cancers.
("Conditionally restricted" means that the maximum of 2 ppm only applies to a drug product in which the use of benzene is unavoidable in order to produce a drug product with a significant therapeutic advance, according to FDA guidance.)
Critics of the report questioned the method used to test the products, calling for more "real-world" use data, and said the temperature used may not be what is expected with everyday use.
Now, both new studies are reassuring about the safety of the products, John Barbieri, MD, MBA, assistant professor of dermatology at Harvard Medical School and director of the Advanced Acne Therapeutics Clinic at Brigham and Women's Hospital, Boston, said in a telephone interview. He was a coauthor of both studies. A leading dermatologist not involved in the new research reviewed the findings and agreed.
- One study using data from the National Health and Nutrition Examination Survey compared blood levels of benzene between 14 people who had used BP products and 65 people without a history of BP product use, finding no difference between the groups.
- The other, much larger study analyzed electronic health records of more than 27,000 patients with acne using BP products, comparing them with more than 27,000 controls who did not use the products. The patients were followed for 10 years after the use of BP products began, and no increased risk for cancer, either blood cancers or solid tumors, was found.
The studies were recently published in the Journal of the American Academy of Dermatology.
"Both studies are well done," said Henry Lim, MD, former chair of the Department of Dermatology and senior vice president for academic affairs at Henry Ford Health, Detroit. Lim, a former president of the American Academy of Dermatology, reviewed the results of both studies.
"These studies indicate that [a] report of detection of benzene in BPO products exposed to high temperature does not have any relevant clinical significance, both in terms of blood levels and in terms of internal cancer," Lim said. "This is consistent with the clinical experience of practicing dermatologists; no internal side effects have been observed in patients using BPO [products]."
Further Details
Under high temperatures, or over a long period, BP can decompose to benzene, a colorless, flammable liquid with a sweet odor. Benzene is formed from natural processes such as forest fires and volcanoes, according to the American Cancer Society, and is found in the air, cigarette smoke, some foods (at low levels), and contaminated drinking water. It's one of the 20 widely used chemicals involved in making plastics, resins, detergents, and pesticides, among other products.
In the study evaluating blood levels, the researchers matched 14 people who used BP products currently with 65 controls who did not. Five (36%) of those using the products had detectable blood levels; 21 (32%) of those who did not use them did. There was no association between BP exposure and detectable blood benzene levels (odds ratio, 1.12; P = .80).
In the larger study, the researchers used the TriNetX US Collaborative Network database, comparing more than 27,000 patients treated with BP products for acne with more than 27,000 patients aged 12-40 years who had a diagnosis of nevus or seborrheic keratosis with no exposure to prescribed BP or any diagnosis of acne, hidradenitis suppurativa, or rosacea. The researchers looked at the database over the subsequent 10 years to determine the risk for either blood cancers or internal malignancies.
Compared with patients diagnosed with nevus or seborrheic keratosis, those with acne treated with BP had no significant difference in the risk for lymphoma (hazard ratio [HR], 1.00), leukemia (HR, 0.91), any lymphoma or leukemia (HR, 1.04), and internal malignancies (HR, 0.93).
The findings suggest no increased risk for malignancy, the researchers said, although they acknowledged study limitations, such as possible misclassification of BP exposure due to OTC availability and other issues.
Value of BP Treatments
BP is the "go-to" acne treatment, as Barbieri pointed out. "It's probably the number one treatment for acne," and there's no substitute for it and it's one of the most effective topical acne treatments, he noted.
Despite the reassuring findings, Barbieri repeated advice he gave soon after the Valisure report was released. Use common sense and don't store BP-containing products in hot cars or other hot environments. In warmer climates, refrigeration could be considered, he said. Discard old products. Manufacturers should use cold-chain storage from the manufacturing site to retail or pharmacy sale sites, he added.
FDA and Citizen Petition Status
Asked about the status of the petition from Valisure, an FDA spokesperson said: "The FDA does not comment on the status of pending petitions."
Barbieri and Lim had no relevant disclosures. There were no funding sources for either of the two studies.
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