ISO 8871-3:2003

Elastomeric closures may be superficially contaminated with visible and subvisible particles, and fragments can also be produced when the closure is pierced by a needle.
Such particles may be transferred to pharmaceutical preparations in contact with the elastomeric parts and affect the quality of such preparations.
ISO 8871-3:2003 specifies methods for the determination of the number of visible and subvisible particles, respectively, detached from elastomeric parts by rinsing.
It does not specify particle contamination limits. These will have to be agreed upon between manufacturer and user.