Have you read the Book called "Silent Spring"? In it, there is alot about toxins. I have some auto immune problems. You mentioned thallium, a heavy metal. Mayo clinic had mentioned that to me in the 80's when I went there. I am starting to make sense of what has happened to me. I see a physiosist now to try to help my health. I feel like these problems are getting steadily worse. Taking B12 was first on this new doctors list for me. I want to stop this PN or RSD spreading, anything more I can do? I am not diagnosed yet, but was told no surgery to correct ankle because of it. thanks if you have any ideas. ginnie