via Plastics Today
All plastics have additives — some obvious, some invisible
First of all, no plastic is 100% pure when it goes into the extruder. All of them have additives — some are obvious, like colorants, and some are invisible, like light stabilizers that keep the Sun’s ultraviolet rays from breaking the molecules and discoloring or weakening the plastic.
HMM — how much matters — is my favorite acronym. I squirm when I hear the words “in it,” as in “it has sugar in it” or “there’s BPA in it.” I want to scream, “How much is in it?” but usually I don’t. Often the speaker wants/needs to avoid dealing with the actual amount. Additives are prime examples: We can’t know a compound is adequately protected from sunlight degradation (UV) without knowing what the additive is, how uniformly it’s mixed, and how much of it is in it.