I generally use stuff as long as I can if I don't notice anything wrong with it. Items will off gas some of the manufacturing chemicals for a while. I have put things like cutting mats in a separate area where they can off gas in peace and quiet. I do try and store leftovers in my glass containers for the most part and never use plastics in the microwave. I also don't use a lot of sprays or chemicals in the house if I can avoid it (OK I am not the best housekeeper so it is good to have an excuse why my house wouldn't pass a white glove test). It is impossible to avoid all carcinogens today. And I don't think anyone really knows what the significance is of those microplastics bits that are now being found in everything including people. Yep, really need to lose the plastic bag habit.