evidence: Claim understates federal limit for safe level of aluminum in vaccines | Fact check [...] "Someone asked ‘What are your reasons why you don't vaccinate?’ One lady responded with: 'My kids don't weigh enough yet!'" the post reads. "'Per FDA guidelines, the max amount of aluminum anyone can safely handle is 4 micrograms per kilo. Most shots are 225 mcg to 850 mcg. So my kids would need to weigh a minimum of around 123 pounds to safely vaccinate per FDA guidelines. And need to wait to hit 467 pounds to safely receive the pediarix vaccine. I don't make the rules, just follow them!'" [...] Federal regulations set the limit of aluminum in vaccines at 1.25 milligrams per dose. Additionally, the amount can be no more than what data shows is needed to cause the desired immune response without health impacts. Aluminum salts are used in vaccines to stimulate a stronger immune response to a vaccine, and USA TODAY has previously reported on a large body of research supporting the safety of the way they are used.