I also don't worry too much about things like this. But... I want to know so if there is an easy choice to make, I can make it. I would worry more if I were younger, or had young kids, because it's often the long-term effects of such things that matter.
Someone mentioned cooking beans in a slow-cooker. I think there have been concerns about making sure beans reach a certain temperature in cooking to deactivate some sort of natural chemical in them. Since I do mine on the stovetop, I didn't pay that much attention to it. It's something to checkout however.
As to tomatoes, we grow them in the summer and there are usually lots to preserve. You can can them, which I no longer do - too much work. Or just pop them in the freezer whole, untreated, esp if you are using them in soups, stews etc and dont mind the seeds or fishing out the skins. And that takes a lot of space. Think of a bag of tennis balls. Or you can just cut them up and roast them down, then bag and freeze them. That's my favorite way - they taste the most yummy.
I dehydrated a fair number this year too. Very pretty, and they taste good as snacks just out of the dehydrator. Just slice and put on trays. In an excalibur, they don't stick.
I wish I had preserved more however, since I've always used a lot. Cans were just easier.
Another day, another danger.