I'm starting on a S&D route, and I DO find it something to worry about. I also don't equate ingested aluminum with injected aluminum. Tomljenovic and Shaw have written about the pharmacokinetics of ingested vs. injected. Notably that only about 0.25% of dietary aluminum is absorbed into systemic circulation (Yokel et al 2008) but that aluminum from vaccines may be absorbed at a rate of 100% (Yokel et al 2001). They also examine the types of aluminum used in the various studies and look at how the different compounds (chloride, hydroxide, lactate) affect neurological outcomes.
I'm not a chemist. Or a neuroscientist. What I wish is that there was a good, solid, credible review of Tomljenovic and Shaw's work done (not just snipes via comments on pro-vax blogs) where someone can address (or refute) point by point the conclusions they have come to. That would help me evaluate whether or not there is inherent risk of permanent injury in injected aluminum hydroxide, not just the old advice (said by Offit as well) that I probably eat more aluminum in a day anyway, so don't worry about it. It does concern me and it affects my decision.
Not to mention that an infant getting many vaccines (at 2 and 4 months) is not likely to be consuming packaged food or anything but breastmilk or formula.