Aluminum adjuvants in vaccines accumulate in the body and cause neurological damage.
Aluminum is ubiquitous in the environment and diet; humans ingest ~7-9 mg daily from food and water. A childhood vaccine schedule delivers approximately 0.5 mg of aluminum adjuvant (typically aluminum phosphate or aluminum hydroxide), a fraction of dietary exposure. Aluminum, like most ingested metals, is excreted primarily through urine and feces within hours to days, with minimal absorption. The concern stemmed from conflating soluble aluminum salts (which can bioaccumulate at high doses) with the insoluble forms used in vaccines. The threshold for aluminum toxicity in humans is approximately 1 mg/kg of body weight; a 10 kg infant would need to be exposed to 10,000 mg to reach this threshold, 200,000 times the amount in a vaccine dose. Studies examining blood and tissue aluminum levels in vaccinated versus unvaccinated children show no differences, indicating that the vaccine aluminum is not accumulating. The CDC and WHO have reviewed aluminium adjuvant safety extensively and concluded that the quantities used are safe at doses tested. The enduring concern reflects a misunderstanding of toxicology's first principle: the dose makes the poison.