Polyacrylamie (IUPAC poly(2-propenamide) or poly(1-carbamoylethyelene)) is a polymer (-CH2CHCONH2-) formed from acrylamide subunits that can also be readily cross-linked. Acrylamide needs to be handled using good laboratory practices (GLP) to avoid poisonous exposure since it is a neurotoxin. Polyacrylamide is not toxic, but unpolymerized acrylamide can be present in the polymerized acrylamide. Therefore it is recommended to handle it with caution. In the cross-linked form, it is highly water-absorbent, forming a soft gel used in such applications as polyacrylamide gel electrophoresis and in manufacturing soft contact lenses. In the straight-chain form, it is also used as a thickener and suspending agent. More recently, it has been used as a subdermal filler for æsthetic facial surgery (see Aquamid).