DEAR MISS MANNERS: I refuse to accept plastic items at gatherings, and do without if there is not another option. Finger foods on a paper napkin work very well, as gatherings that use plastic tend to be casual. I take paper goods as my contribution, so others have a choice, also.
This is done without getting on a soapbox or offending the host. This planet is drowning in plastic, and each person can make a difference, starting with their personal choices. If one can refuse to eat meat, one should also be able to refuse, tactfully, plastic.
GENTLE READER: Well, yes, but here on the ground (as opposed to up on the soapbox), the way to do that is not to draw attention to why -- or what -- one is refusing. Just as Miss Manners objects to the guest who explains in detail why she hates mushrooms, she believes that a guest with a preference for paper should confine her answer to a polite, enigmatic refusal.