Talk to an anti-vaxxer long enough and they'll probably tell you all about the cocktail of dangerous "toxic chemicals" that are in vaccines. Unfortunately (or fortunately, depending on how you look at it), these claims are based on a basic misunderstanding of how science works and a misplaced distrust of the word "chemicals", which for some reason has become a dirty word in some circles (and doesn't take into account the fact that everything is made of chemicals. Everything). The substances that are most often highlighted are mercury, formaldehyde, aluminium and sodium which, sure, sound a bit scary, but they're not just being chucked in there by evil pharma for no good reason. Aluminium hydroxide, for example, makes the vaccine more effective by boosting the immune response. Formaldehyde deactivates the viruses in your vaccine so that, you know, you aren't injected with full-blown meningitis. The anti-vax argument also ignores the fact that toxicity is dependent on dosage; anything is toxic if you have too much of it. Water would poison you if you had too much, that's what "too much" means. The chemicals present in vaccines are in such minuscule quantities that they can not be considered toxic. In fact, formaldehyde is produced in the body in much higher quantities (about 5000% more per day to be exact) and is essential for metabolic processes. A baby can break down the unwanted material in vaccines in a matter of minutes.