Hand sanitizers were tainted by benzene. Sunscreens and dry shampoos too. Now acne treatments are joining the list of widely used consumer products found to contain high levels of the chemical linked to cancer.

Acne products from brands including Proactiv, Target Corp.’s Up & Up and Clinique have elevated levels of the carcinogen, an independent testing laboratory said in a petition filed with the US Food and Drug Administration late March 5. The lab asked the FDA to recall the affected treatments — all of which contain the active ingredient benzoyl peroxide — while regulators investigate.

Benzene is a natural component of gasoline and tobacco smoke and can cause leukemia in high amounts, according to the US Centers for Disease Control and Prevention. Over the past three years it’s been detected in several popular products, heightening consumers’ awareness of the potential threats in their bathroom cabinets and raising questions about the FDA’s oversight of the industry. Companies including Johnson & Johnson, Unilever Plc and Procter & Gamble Co. have recalled products.

New Haven, Connecticut-based Valisure LLC, the testing laboratory that filed March 5’s petition and uncovered the previous risks, has positioned itself as a gatekeeper for consumers. Valisure gained prominence conducting product research and has deals with large health-care systems, including Kaiser Permanente and the US Department of Defense, to test drugs used by their members and weed out substandard treatments.

For its acne research, Valisure tested 66 benzoyl peroxide products, including creams, lotions, gels and washes available either over the counter from major retailers or via prescription. While FDA guidelines allow up to 2 parts per million of benzene, Valisure found up to nine times that amount in some treatments. Those levels jumped significantly when the products were tested at higher temperatures designed to replicate how they might break down over time, for example if stored in a medicine cabinet in a steamy bathroom.

Proactiv’s 2.5% benzoyl peroxide cream, manufactured by Taro Pharmaceutical Industries Ltd., contained as much as 1,761 parts per million of benzene during Valisure’s stability testing, while a similar cream from Target reached 1,598 parts per million and a treatment from Estee Lauder Cos.’s Clinique hit 401 parts per million. A 10% benzoyl peroxide cream from Reckitt Benckiser Group Plc’s Clearasil initially tested just at the FDA limit, but jumped to 308 parts per million of benzene after being exposed to high temperatures for more than two weeks.

“Reckitt is confident that all Clearasil products, when used and stored as directed on their labels, are safe,” the company said in a statement. The safety and quality of products are its top priority, Reckitt said. It didn’t answer questions about whether it had tested its acne cream for benzene.

Representatives for the FDA, Taro Pharmaceuticals and Estee Lauder didn’t respond to requests for comment. Target declined to comment. Reckitt fell 2% and Unilever dipped 0.4% in London, while Estee Lauder slid 1.3% and Taro tumbled 2.4% at the close in New York.

Acne is the most common skin condition in the U.S., and affects as many as 50 million people each year, according to the American Academy of Dermatology. The numbers are even higher among teenagers and young adults: about 85% of those aged 12 to 24 have some form of the condition.

Sales of over-the-counter US acne treatments totaled $1 billion last year, almost double the $593 million in sales in 2019, data from Chicago-based market research firm Circana showed. The AAD guidelines name benzoyl peroxide as one of its top recommendations for treating acne topically.

Valisure President David Light said the contamination happens because benzoyl peroxide can break down and form benzene.

“This has been well known for a long time,” he said in an interview. “All that was needed was for someone to check on it.”

Light is listed as an inventor on a patent filed last year for a method to prevent benzoyl peroxide from breaking down into benzene in drug products. The lab tested other kinds of acne products with different ingredients, mainly salicylic acid, and did not find elevated benzene levels in those.

Valisure’s most high-profile investigation was into heartburn drug Zantac, which the FDA pulled from the market along with generic versions in 2020, months after the lab discovered the drug’s active ingredient — ranitidine — could form a probable carcinogen called NDMA.

The FDA has questioned Valisure’s testing methods in the past. Specifically, the agency has said the independent lab should follow the same process that drug manufacturers use, which tends to be costlier than the way that Valisure tests.

Valisure stands behind its testing methods and points to its certification from the International Organization for Standardization, which sets testing guidelines for all kinds of products including drugs. In a statement on March 6, Valisure said the results from its research on acne treatments were most similar to its investigation into those ranitidine products.

“The benzene we found in sunscreens and other consumer products were impurities that came from contaminated ingredients; however, the benzene in benzoyl peroxide products is coming from the benzoyl peroxide itself,” Light said in the statement.

In 2022, following Valisure’s previous benzene findings, the FDA warned companies that they should assess the risk of the chemical forming in their own products. The agency doesn’t regularly test products it oversees.

“The discovery made by Valisure regarding benzoyl peroxide acne treatment products is deeply troubling and gives renewed importance to the need to empower the FDA to immediately act once we are made aware of the dangers of prescription or over-the-counter drugs,” US Representative Rosa DeLauro, a Connecticut Democrat, said in a statement. “Benzoyl peroxide products saturate the current market and millions of consumers are unknowingly using a product that increases their exposure to life-threatening carcinogens.”

DeLauro has attempted to push legislation that would give the FDA the authority to recall drugs rather than negotiate with companies to do so on a voluntary basis.

Valisure’s testing also examined benzene in the air surrounding acne treatments and found that even an unopened Proactiv product leaked high levels when kept at 104 degrees Fahrenheit, the temperature of a hot shower, for almost 17 hours. The Environmental Protection Agency has said inhaling benzene at levels of 0.4 parts per billion chronically over a lifetime could result in one additional cancer per 100,000 people, a measure of risk the FDA also uses.