There have been studies in the medical device industry, specifically for Intravenous sets that must be clamped and them opened to allow full flow. Perhaps you can do a search along those lines and find a page with that information. I believe that many formulations of PVC will begin to leach plasticizer in less than five years.
Shelf life for most products top out around the five year time frame.
It is hardly too strong to say that the Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern well, but they mean to govern. They promise to be good masters, but they mean to be masters.”
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