Organic compounds of silicone, with a structure of alternate atoms of silicone and oxygen, and organic groups – such as methyl and phenyl – attached to the silicone atoms. As they produce a flexible and stable water-repellent film on the skin, they are used as BARRIER CREAMS.

Silicone is also used to make implants for RECONSTRUCTIVE (PLASTIC) SURGERY. Silicone oil in a silicone rubber bag is used in breast reconstruction after surgery for breast cancer, and for enlargement of the breast. Although usually an inert substance, it has been found to cause side-effects, including possible immunological reactions following leakages, so that its use in breast surgery in particular has now been restricted.