Omadin, known as polyacrylamide hydrogel, is a colorless and transparent jelly-like liquid substance. on April 30, 2006, the State Food and Drug Administration revoked the medical device registration certificate of Omadin, and comprehensively stop its production, sale and use. Amide hydrogel is a chemical compound, the monomers that make it up are highly toxic, while the compounds are non-toxic, but when injected into the human body, they will decompose to produce highly toxic. Due to the ability to decompose into highly toxic monomer molecules in the human body, poisoning the nervous system, damaging the kidneys, and causing harm to the life circulation system, the World Health Organization has listed this substance as one of the suspected carcinogens, a time-dependent dangerous bomb.