These microplastics are digestible by your immune system, though, which makes them ultimately harmless. PLA is used for drug delivery for this reason.

Being concerned about incomplete PLA degradation is like being concerned about a piece of wood breaking down into micro-woods. Yet even if you get a dangerous shard of micro-wood embedded in your skin, your body can deal with this cellose polymer just fine.

Ultimately it will break down completely someday and in the meantime, nothing will be harmed.