I've had thin PLA samples sitting in bio and methanol for at least 6 months. The bio samples seem unaffected as far as I can tell. the methanol samples also appear to be unaffected, but the methanol appears to have "something", a bit like clear strands floating in it.
I've also used the aforementioned foot in quite strong acid, all be it briefly, and that too seems to be surviving.
It would be good to have some corroborative tests if you fancy doing them.