You (and the OP) might like to have a look into the Failsafe diet, www.fedupwithfoodadditives.info/
there is a lot of information freely available on the site including a list of the "nasty additives" by both chemical name and number. I am working on eliminating those chemicals from my diet (some of the preservatives are hard to avoid! Mainly 202). My SIL has fully implemented the diet and is finding it works both in the behaviour of her children, particularly her second son (she has 4, 3 boys one girl) as well as helping greatly with her own depression, and with physical symptoms (eczema with 2 kids, digestive issues). The diet is based on one recommended by one of the major Sydney hospitals in their asthma and allergy unit (it's probably Royal Prince Alfred, or else Royal North Shore - they are both major research hospitals).
Much of the info on the website is about Australian products/labelling laws etc, but much is international, and there is a yahoo group for USA followers to chat/share info/organise meetings etc.
Oh, and one PP stated that all dyes are synthetic, when they aren't - natural tumeric has a very mild flavour (unnoticible in rice, for example) but gives a lovely yellow, as does the synthetic tartrazine; and cochineal is derived from crushed beetles, not petrochemicals. There are more, but I'll limit things here. While I believe the synthetic chemicals are the most likely to be harmful, many naturally-occurring elements and compounds can be harmful too (and some people can be quite sensitive to some chemicals that others aren't, no matter what the origin of that chemical is...)