Prohibited substances in cosmetics refer to substances which must not be among the raw material ingredients of cosmetic products. These substances are absorbed mostly through skin, as well as via lung and gastrointestinal tract. Polyacrylamide is ubiquitously used in industry and its decomposition residue acrylamide (ACR) easily finds its way into cosmetic products. ACR can either be oxidized to epoxide glycidamide or conjugated with glutathione, hemoglobin or DNA; ultimately it is excreted in urine. ACR causes neurotoxicity, reproductive toxicity and tumors in rodents. Occupational exposure to ACR causes neurotoxicity in humans; however, epidemiological evidence have not unambiguously answered the question of whether ACR exposure can increase cancer risk for humans.