They may have changed the plastic. Ten years ago or so my local club had (I forget his name) had a guest speaker who was one of the first to raise captive bred clowns and a few other species. He did a talk about his experiences and some of the pitfalls that he found along the way.
One was that clown larvae are attracted to light and they would literally bash their brains trying to get to anything bright in if not raised in the dark. They started using Brute cans because every reefer uses Brute cans. They found that all of the fish became deformed. They switched to glass tanks painted black and everything was fine. His theory was that something in the grey, not food safe, cans was causing damage to the tiny fish.
There's also been a few other reports from roughly the same time period of studies done on marine life where the scientists used grey Brute cans (like everyone does). I remember reading that chromosomal damage was occurring when the Grey cans were used. The food grade seemed ok.
Again this was roughly ten to twelve years ago. It's possible that Rubbermaid is using the same plastic for their FG (food grade) and non FG cans. Also proving (or disproving) chromosomal damage would probably take a breeder or at the very least some long term studies with controls. Otherwise like most things in this hobby it's heresay and anectodal evidence at best.
Just a few years ago we found out that BPA wasn't good and for a decade (or more) it's what we made baby bottles out of. That entire time everyone thought BPA was totally safe. Now we know it can disrupt quite a bit in a small persons body.
I like to stick with containers made to hold potable water. It's the same price, I'm not reinventing the wheel or trying to put a square peg in a round hole. I never feel safe with those Brute cans. I always feel like it might bend and dump water all over. Polyethylene cans are made to hold water, even high SG water and are as tough, if not more than Brute.
