Scott, that is an intelligent and reasoned letter, but I agree with John that you are probably wasting your time. Dr. Barrett and his associates on the American Council on Science and Health/Quackbusters, etc. are bought and paid for by big industry. An example:
The head of the ACSH is Elizabeth Whelan. She claims there is no link between heart disease and a diet high in fat. What she doesn't tell you is that she received funding from Oscar Mayer, Land O'Lakes and Frito Lay. She makes a LOT of claims like that. She (and those like Dr. Barrett)are not paid to be consumer advocates, but corporate cheerleaders.
A great book to read is "Toxic Sludge is Good For You".