breast implant, saline- or silicone-filled prosthesis used after mastectomy as a part of the breast reconstruction process or used cosmetically to augment small breasts. An implant consists of a fluid-filled, malleable pouch that is designed to mimic to the look and feel of natural breast tissue when inserted into a pocket created under the skin in a procedure called a mammoplasty.

After reports that leakage from silicone-filled implants might be causing autoimmune diseases (e.g., lupus, arthritis, scleroderma) in some women, the Food and Drug Administration in 1992 called for a moratorium on their use outside clinical trials. The ensuing scare resulted in the largest product liability settlement in U.S. history and the Chapter-11 bankruptcy of Dow Corning Corporation, one of the makers of the implants. Despite legal settlements in the billions of dollars, the claims against silicone-filled implants remain anecdotal; numerous scientific studies have found no link or only a weak equivocal link between the implants and disease. The use of silicone-filled implants was again approved by the FDA for reconstructive surgery in 1998 and for cosmetic surgery in 2006.

In 2010 silicone-filled implants manufactured by the French company Poly Implant Protheses (PIP) were banned after it was discovered that the firm had used industrial-grade, instead of medical-grade, silicone gel. Industrial-grade silicone has more contaminants, and French authorities advised (2011) that French women have the implants removed because they were believed to have a higher than normal incidence of rupture. Some countries adopted similar recommendations, while others did not; the implants had not been licensed for use in the United States. A 2012 British report on the PIP implants found that the gel used in them did not constitute a long-term health threat.

See M. Angell, Science on Trial (1996).