橡胶是最常见的，但橡胶交联过程需要催化剂等有毒物质。 即使有多步的清洗过程，
有毒物质是不能彻底清除的。最终有毒物质或多或少会到液体药物中，致使药物失效。
最近的一个例子是BD的：http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm458955.htm
FDA is alerting health care professionals not to administer to patients
compounded or repackaged drugs that have been stored in 3 milliliter (ml)
and 5ml syringes manufactured by Becton-Dickinson (BD) unless there is no
suitable alternative available. Preliminary information indicates that drugs
stored in these syringes may lose potency over a period of time due to a
possible interaction with the rubber stopper in the syringe.
虽然没有提具体原因，基本可以推断就是橡胶中的残留物质。这类应用一定得用便宜得
橡胶吗？感觉药物很贵，橡胶塞成本算不得什么，那么高价的新材料也许可以有用武之
地。
