• Posted October 9, 2024

Common Acne Drug Might Become Carcinogenic at Room Temperature

Widely-used acne creams can become contaminated with a known carcinogen even if kept at room temperature, a new study warns.

Creams containing benzoyl peroxide (BPO) can wind up containing high levels of benzene while sitting on a store shelf or in a medicine cabinet, researchers found after testing 111 products from major U.S. retailers.

Brands tested containing benzoyl peroxide included products from Clearasil, Clean & Clear, Neutrogena, Proactiv, Up & Up and store brand equivalents.

Benzoyl peroxide degrades into the carcinogen benzene over time when stored at room temperature, at elevated temperatures and when exposed to the ultraviolet rays of sunlight, researchers reported Oct. 7 in the Journal of Investigative Dermatology.

This is the first time that benzoyl peroxide products have been shown to degrade into benzene at normal temperatures, they noted.

“Our research demonstrates that BPO products can generate benzene at typical room and store shelf temperatures, while cold storage significantly reduces this formation,” said researcher Dr. Christopher Bunick, an associate professor of dermatology with the Yale University School of Medicine in New Haven, Conn.

The Environmental Protection Agency classifies benzene as a known human carcinogen, noting that it specifically increases the risk of leukemia.

Benzoyl peroxide acts as an antibacterial agent, and is found in over-the-counter remedies and prescription creams for acne and rosacea.

For the new study, researchers bought dozens of acne creams from major retail stores in California, Connecticut, Florida, Illinois, New York and Texas. 

“The 111 BPO drug products tested from major U.S. retailers appear to be substantially contaminated with benzene when tested shortly after being acquired off the shelf,” they concluded.

About 34% of the products tested contained benzene concentrations above the U.S. Food and Drug Administration’s conditional limit of 2 parts per million for medications, results show. 

However, there are no safe levels of exposure to benzene, researchers noted. The FDA says benzene has “unacceptable toxicity,” and its conditional limit is for “unavoidable” levels of benzene contained in drug products “with a significant therapeutic advance.”

The researchers’ testing revealed benzene concentrations in the products as high as 35.3 parts per million. 

Testing also showed that refrigeration can slow benzoyl peroxide’s degradation into benzene, researchers said.

“These findings suggest a need to recommend refrigeration of BPO products throughout the supply chain -- from manufacturing to patient use-- to limit benzene exposure,” Bunick said in a journal news release. “Until formulations are developed to prevent benzene formation, refrigeration may serve as a practical solution to minimize unnecessary exposure.”

Dr. Richard Gallo, chair of dermatology with the University of California, San Diego, said that “this carefully done analysis should put to rest the question of whether benzene is present in skin care products that contain BPO.”

“It is now important that further studies be conducted to determine if the presence of this potential carcinogen in drugs with BPO translates into any increased risk of cancer,” added Gallo, who was not involved in the study.

More information

The U.S. Environmental Protection Agency has more on benzene.

SOURCE: Elsevier, news release, Oct. 9, 2024