L’Oreal SA is recalling all lots of its acne treatment Effaclar Duo in the US because of concern that the creams are contaminated with benzene, a known carcinogen.

L’Oreal’s Effaclar Duo, sold under the French company’s La Roche-Posay brand, is made with benzoyl peroxide, which kills bacteria to help treat acne. Valisure, an independent lab in Connecticut, flagged benzene contamination a year ago in many popular benzoyl peroxide products and asked the US Food and Drug Administration at the time to recall the contaminated treatments. The FDA didn’t immediately respond to a request for comment asking whether more acne treatments would be recalled.