About plastic safety for aquatic life

Hi, y'all!

I've seen lots of tutorials of aquarium related diy projects using plastic elements, mostly containers, but they don't seem to address which plastics should be safe to use. Some just mention to use food grade ones, but mostly it seems they use whatever. I assume it's usually polypropilene (PP), since they use containers like plastic pots, boxes, chest of drawers... But there are also videos using random items like brushes, shower sponges and whatnot.

I want to use PP boxes for filters, quarantine, etc, but it's difficult to find food grade ones and I want to know if PP is safe as I've read in some places.

I also wonder how safe is fish keeping equipment and decoration, since most of it is plastic.

If it's of any use regarding regulations and all that, I'm from EU.

Thank you in advance!