Do you know that?/You know what? Do you know that?/You know what? A few years ago, breast augmentation by injection was popular in China, and many female friends accepted this operation. A few years later, all the female friends who had this kind of operation were experiencing different degrees of pain. Injection breast augmentation is to inject hydrophilic polyacrylamide gel (HPAG) into the posterior breast space. Gel is an inert biocompatible material, and its operation is relatively simple. However, according to the practice of the world plastic surgery organization, this injection breast augmentation method can be surrounded by hyperplastic fibrous connective tissue and form induration, resulting in breast deformation and pain. The most troublesome thing is that it can't be completely taken out of the body. Some experts in China injected polyacrylamide gel into animals for toxic and side effects experiments. The results show that acrylamide monomer can be absorbed through skin, respiratory tract and digestive tract and distributed in kidney, liver, brain, spinal cord and sciatic nerve, which can have neurotoxic effects on all kinds of animals, and its symptoms include imbalance of supply and weakness of limbs. The experimental study shows that polyacrylamide gel is toxic to cells cultured in vitro, and it is also toxic to kidney in different degrees after subcutaneous injection in SD rats, which is characterized by swelling, degeneration and necrosis of renal tubular epithelial cells, falling off and forming tubes in the cavity, with a high incidence. Another expert experiment shows that injection of polyacrylamide gel can produce complications such as hematoma, infection, traumatic aseptic inflammation, pectoralis major myositis, induration, breast asymmetry, gel displacement and so on.