PNNL

Abstract

A physiologically based pharmacokinetic model was developed to describe the silicone constituent octamethylcyclotetrasiloxane (D4) and its migration from intact or ruptured silicone gel-filled breast implants into surrounding tissues. D4 is a representative low molecular weight constituent of silicone gel that is soluble enough in biological fluids to migrate from the implant and into surrounding tissues. The simulations were based on a representative young adult (pre-menopausal) woman and a mature (post-menopausal) woman using worst-case exposure conditions (i.e. complete rupture of the largest implant available; maximum levels of D4 in silicone; equal solubility of D4 in breast tissue and gel; and a range of breast tissue fat contents). The results indicate that D4 is cleared primarily by exhalation with highest concentrations achieved briefly in breast tissues of a representative post-menopausal woman. Maximum D4 levels in breast tissues for this scenario were estimated to be approximately 750 ppb with over 90% cleared in about 20 days. Thus, it is unlikely that D4 would be detected in any tissue within a few weeks of receiving an implant, even if immediately ruptured, under the assumptions used in this model.