How do you dispose of old x-rays?

Your city probably has a hazzardous waste policy. I'd call them and ask. Many have a drop-off point for this type of waste.

Thanks for asking. This is an interesting question many wouldn't wouldn't think of asking about!
Carol

You can cut them up into pieces if you are concerned about his privacy. Or, you could donate to any crafters that you know. (Cut his identifying information off first) Old x-ray film can be cut with an exacto knife to make a template for quilt patterns, for stencils, etc.

they could always be shredded, but will you need them in the future to prove a point?

There really isn't a good answer for this. Many people are given copies of their x-rays and I'm sure they go in the trash, just like all the other landfill toxins. I would call the x-ray department and ask if they can dispose of them for you. I'm sure they have a big box of film (rejects) that is recycled. I worked in x-ray for most of my life and you should get a pat on the back for even considering the environment!