Sometimes the UHT milk I use has some small floating white particles (about 1 cm long, few mm wide)
This is milk that has been kept sealed at room temp (30-35C) for about 2 months
Any way to know if its safe?
In my experience, sometimes the uht milk can be a bit dense so the bits that are stuck to the top/opening of the tetrapak can dry out and look like nail clippings dropped into the liquid milk. Perhaps this is what you have? If the milk doesn't taste off and it's only a small amount, that's probably what it is. The milk otherwise is safe to consume.