Below is a clip of Dr. Chris Shaw, a Neuroscientist and professor at the University of British Columbiaexplaining the dangers of putting aluminum into vaccines as an adjuvant. Keep that word in mind: adjuvant.
As pointed out in the video, a common argument from the "pro-vaccine" side when it comes to vaccines that contain aluminum is that aluminum is present everywhere, that we ingest it more from our food (and other things) than we do from vaccines. This argument is completely invalid, because when it is in the form of an adjuvant within a vaccine, as Dr. Shaw explains, the aluminum stays in your body. That's exactly what it's designed to do, that's the purpose of an adjuvant.
On the other hand, when you accumulate aluminum in your body from food, industrial practices, or any other source, our bodies usually do a good job flushing it out. Again, when it's in a vaccine the body does not do this, it stays in the body and this is why vaccines that contain aluminum (and other harmful toxins) should be a cause for concern.
Comment: Additional information on the negative health impacts of aluminum: