I use them to connect all my 4 hoses to the platechiller after cooking.
Word is, these fittings aren't foodgrade safe.
Don't know about availability, but over here I can buy the same (different brand but compatbile) made from messing.
If you keep them sanitized it has nothing to do with bacteria. It is more the 'problem' that there cold be stuff (plasticizers?) in the plastics that dissolves uder warmer temps.
Plastics that are foodgrade don't have that.
But again, I use it on my cooler so my hot and cold wort goes through these connectors