As you can imagine, not every possible medical deduction can be listed in Pub 502.
Does Terracycle charge you as part of the cost of buying the gloves? Then, yes, deductible on Schedule A as a medical expense.
But if you pay separately to recycle because it is in the public interest, then you could deduct that charge, and make that argument to the IRS if they ever question this deduction (I can't guarantee that they will accept that).
On the "third" hand, if there is something special about your parents' condition that requires the recycling (like disease or whatever), then, yes, this cost would be deductible as "Medical expenses are the costs of diagnosis, cure, mitigation, treatment, or prevention of disease, ..."
Whatever you decide, just document your reasoning, and stick it in your tax file, if anyone ever asks.
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