I just paid three times the normal price ($6+ vs. $2+) for a shower curtain liner that was 100% EVA. I am now trying to find out what EVA is and saw your question. I'm on my way to an answer and hope you are too!
This is what I've been able to find thus far. Can't find much on ethylene vinyl acetate (EVA), more is available on vinyl acetate (VA). Both are discussed in this study.
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EVAs are used in the production of adhesives (hot melt), various padding (shoe soles, sports gear, carpet, etc.), and plastic film (solar/photovoltaics, food packaging, etc.).
Also used to make...