Jason, If you do a search of past discussion topics on the pd listserv, you'll find some info that I and others have also previously posted on the subject of MTPP. A very good book about the brain, which includes a whole chapter on MTPP, is "Receptors," by Richard M. Restak, M.D. He also mentions the fact that paraquat & diquat, two herbicides/pesticides, are chemically similar to either MTPP itself or its byproduct, MTP+, and since MTPP via its chemical breakdown in the body can cause damage which leads to pd, it is no stretch to wonder also about these chemicals. If you can't find any of the earlier postings let me know and I can try to dredge them up. Wendy