Valisure has also filed a petition with the US Food and Drug Administration, calling on the regulator to recall the products, conduct an investigation, and revise industry guidance, the New Haven, Connecticut-based lab said today.

Estee Lauder EL.N shares dropped 3% following the report.

Benzene could form at “unacceptably high levels” in both prescription and over-the-counter benzoyl peroxide acne treatment products, Valisure said.

Other products that benzene was detected in include Proactiv, PanOxyl, Walgreens’ WBA.O acne soap bar, and Walmart’s WMT.N Equate Beauty acne cream.

Target TGT.N, Estee Lauder, Walmart, and Reckitt RKT.L did not respond to Reuters requests for comment. The FDA has not yet responded to Valisure’s petition.

The carcinogen has already been found in several consumer products, including sunscreens, hand sanitisers, and dry shampoo, leading to recalls of products made by companies including Procter & Gamble PG.N and Johnson & Johnson JNJ.N.

But the detection of benzene in the acne treatment products was “substantially different” from the other cases, Valisure said.

“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,” said Valisure’s co-founder and president David Light.

Valisure’s tests showed some products could form more than 800 times the conditionally restricted FDA concentration limit for benzene.

High levels of benzene were not only found in the acne products but also the air around incubated products, indicating that the carcinogen could leak out of some of the packages, posing a potential inhalation risk, Valisure said.

Bloomberg News had reported the development earlier in the day.