OK the rubber used in stoppers for vials is a compound which was made for storage of compounds long term, or the term of the use by date of the compound. The single use syringe is exactly that. it was not intended for long term storage of any compound. Load, use, discard of properly. certain solvents used to keep AAS in solution such as BA, BB,etc can act on the rubber in the syringe causing it to soften or breakdown significantly, thus releasing the compounds used to manufacture the rubber, usually petroleum based. This occures over long term exposure to the solvents used in manufacture of AAS. Solvent in general will break down petroleum based products, this is why solvents are used to clean up petorleum nd iol spills. Now I know this all sounds pretty dramatic but these solvents can act on that little rubber plunger over time........just how long that is well a little research on that might help, but I have never tried to find out the hard way. So the contamination of your gear I speak of is foreign matter and chemical contamination. You do not want to inject that shit into your muscle or any part of the body.