So awkward, but come on it says right there on the package to wash those mushrooms or whatever it is… You’re not their mom but you don’t wanna eat feces or whatever ended up on the produce. A quick rinse is never going to be perfect but it’s better than nothing.
In the absence of legitimate suggestions, commiseration is welcome too 😉
“Do you mind if I wash these? I’m allergic to pesticides, even in trace amounts.”
No need to fabricate some lie, as that might backfire at some point.
“Hey I would be more comfortable if the vegetables were washed. Do you mind if I wash them?”
Or just offer to help and start washing them.
The important thing is to not make it about them, but about you. Most people don’t get offended when you make it all about yourself, and not them doing something wrong.