It's one or two rats chewing trough there, once the hole is in, the other rats will just use it without having to chew any of the plastic.
But now you have literally toxic garbage bins, plastic waste is already hard enough to get rid off, making it toxic certainly wouldn't make that any easier.
Those toxins would then filter up and down the food chain. Surely there are many better ways to combat rats than introducing poisons into the environment.
That's actually not a bad idea. Only problem is that one rat's going to get birth control drugs and get his fill of trash. All of the other rats don't need to chew through the can after the first one's made the hole for them.
But now you have literally toxic garbage bins, plastic waste is already hard enough to get rid off, making it toxic certainly wouldn't make that any easier.