Georgia has the CDC in its backyard to talk up the importance of childhood immunizations, but the anti-vaccine movement gained some high-profile supporters in California with a new law there that requires all public school children receive vaccinations.

Actors Selma Blair and Kirstie Alley blasted the law, which starting next year will no longer allow immunization exemptions based on a religious convictions or "personal belief" that vaccines might be harmful. (Exemptions remain for medical reasons and kids being homeschooled).

Actor Jim Carrey was the most prolific of all in his attacks, unleashing a series of Tweets that called the CDC "corrupt" in the vaccine debate and blasted California Gov. Jerry Brown a "corporate fascist" for signing the bill into law.

"California Gov says yes to poisoning more children with mercury and aluminum in manditory [sic] vaccines," Carrey posted on Twitter on June 30.

Carrey, who dated anti-vaccine crusader and former Playmate and TV host Jenny McCarthy, continued his barrage on social media through Tuesday, several times to insist he was "pro-vaccine" but "anti-neurotoxin."

The myth that "mercury" causes autism ranks up with the flat-earth as among the most debunked scientific theories in history. PolitiFact Georgia walked through that false debate earlier this year, ruling it a ridiculous Pants on Fire !

But aluminum as a poison? We reached out to Carrey and his representatives several times, but never heard back about his source or explanation.

The actor’s Twitter feed cites a book edited by environmental attorney Robert F. Kennedy Jr., that continues to posit the thimerosal-autism link, but it makes no mention of the aluminum claim.

So, we brushed off chemical books – well, looked at some scientific encyclopedias online – to see if we could sort that part out.

Aluminum in vaccines

Aluminum is literally everywhere. It is the third most abundant element on earth and the single most abundant element in the earth’s crust.

It sits on the Periodic Table of Elements with "other metals." But unlike boron, needed in trace amounts in humans, and Thallium, a highly toxic element, aluminum has no known biological function nor significant toxicity.

As such, its function in vaccines is far different than thimerosal, or ethyl mercury.

Thimerosal was added to multi-dose vaccines (but not live shots, such as the MMR vaccine for measles, mumps and rubella) to act as a preservative against bacterial infections. It could be removed by simply making vaccines single-vial doses, said Dr. Walter A. Orenstein, a professor of medicine and pediatrics at Emory University and the associate director of the Emory Vaccine Center.

Aluminum salts or gels are added to vaccines as "adjuvants," enhancers that boost the immune system response of the shot.

A 2011 report by two Canadian researchers raises questions about whether that boost is worth the potential risk.

Dr. Lucija Tomljenovic and Dr. Christopher Shaw raise the possibility of overexposure to aluminum as potentially toxic and a cause of autoimmune disorders.

"The widespread presence in the human environment may underlie a number of (central nervous system) disorders," their paper concludes. "The continued use of aluminum adjuvants in various vaccines for children, as well as the general public, may be of significant concern."

It’s worth noting, though, that the paper is a theory, not a scientific study.

Several scientific websites have debunked the conclusions, citing decades of research by the Centers for Disease Control and Prevention and U.S. Food and Drug Administration that show aluminum is safe, and necessary.

"Aluminum is an essential component in boosting the immune responses," Orenstein said. "We have no scientific evidence there is damage. We do have scientific evidence that there are bad diseases that aluminum in vaccines can prevent: cancer with the Human Papillomavirus vaccine, Diphtheria with the DTaP vaccine, and so on."

Toxicity?

That said, there is such a thing as aluminum toxicity. Medical research shows it tends to occur in patients with significant kidney damage, or limited kidney function, who are also fed intravenously.

In other words, there must be a specific spike in aluminum exposure – from the IV feeding – with simultaneous damage to one of the body’s essential trash collectors.

That makes aluminum toxicity exceedingly rare – even as immunization rates have increased over time, said Dr. Paul Offit, a professor of pediatrics in the infectious diseases division at The Children’s Hospital of Philadelphia.

Meanwhile, the CDC reports more than 2,200 alcohol poisoning deaths in the U.S. each year – an average of 6 such deaths every day.

And water intoxication – a rare instance of overhydration that throws off the body’s sodium levels – killed a 10-week old Gwinnett County baby earlier this year.

The key? To paraphrase the founder of toxicology, Paracelsus, the dose makes the poison.

When it comes to aluminum, the FDA has concluded that a year-old baby given vaccines according to the recommended schedule will receive about 4.225 mg of the element over the course of a year.

But remember that aluminum is in just about everything on earth, and the body can process it.

A breast-fed child will typically ingest about 7 mg of aluminum in its first year, Offit said. For formula fed, it’s 38 mg. Soy formula, 117 milligrams.

"It’s the most abundant metal on earth’s crust, so if you live on the earth’s crust, which everyone with the possible exception of Jim Carrey does, you are exposed to aluminum," Offit said.

Ouch.

But given the miniscule amounts of aluminum in question in vaccines, Offit raises the critical point about what makes something toxic.

Our ruling

Actor Jim Carrey called aluminum a poison and toxin. Like many other chemicals, it could be, in dosages and scenarios that are rare.

There is no scientific evidence suggesting otherwise. In fact, the only debate stems from a theory, not research that contradicts decades of immunizations.

Attaching scientific sounding terms like "neurotoxin" can lend a sheen of respectability or fear depending on the usage. Look at the willingness of people to sign a petition banning Dihydrogen Monoxide (you probably call it water).

But the fact is, Carrey’s claim has no basis in fact and ignores several studies that contradict it.

We rate the claim False.