If you’re an enlightened pet owner, then you probably know about Thimerosal. If you’re really on the ball, you’ll ask your vet for Thimerosal-free vaccines. But are these vaccines what they claim to be? Why You Should Say No to Thimerosal Thimerosal is a mercury-based vaccine additive that’s been used as a preservative for decades. In 1935, five years after Thimerosal was added to vaccines, Eli Lilly (the creator of Thimerosal), was contacted by veterinary vaccine manufacturer Pittman-Moore after they declared Thimerosal to be completely safe. Pittman-Moore wrote to them: “We have obtained marked local reaction in about 50% of the dogs injected with serum containing dilutions of Merthiolate (Thimerosal). Merthioiate is unsatisfactory as a preservative for serum intended for use on dogs.” (Director of Biological Services, Pittman-Moore Company, letter to Dr. Jamieson of Eli Lilly Company dated 1935. U.S. Congressional Record, May 21, 2003, E1018, page 9). We’d agree with that statement! Since then, over 160 studies have also shown the dangers of Thimerosal.

A Sordid History Since its introduction eighty years ago, Thimerosal has suffered a less-than-spectacular track record:

More Cover-ups Despite all of the research to the contrary, the Center for Disease Control (CDC) assures consumers that “low doses of thimerosal in vaccines do not cause harm, and are only associated with minor local injection site reactions like redness and swelling at the injection site.” But authors Brian Hooker PhD et al recently took the CDC to task on this statement and they found that the CDC’s safety research is flawed and falsified. The article, published in BioMed Research International, states that while there are over 165 studies that have focused on Thimerosal, the CDC stance that there is “no relationship between [Thimerosal] containing vaccines and autism rates in children”  is based on just six studies, which were coauthored and sponsored by the CDC. Moreover, one of the studies cited by the CDC shows a 7.6 fold increased risk of autism in infants exposed to Thimerosal. Hooker et al blew the lid off the CDC’s claims of safety and exposed their sponsored studies as biased, with some of these studies even showing Thimerosal to decrease the risk of autism! Of course, the more than 150 independent studies found Thimerosal to increase the risk of serious neurological disorders. Thimerosal Free Vaccines? Today, veterinary vaccines still contain Thimerosal – despite the dire warning signs that have been present for nearly a century.

But what of Thimerosal-free vaccines? A few companies are making Thimerosal-free canine rabies vaccines. Merial makes a Thimerosal free rabies vaccine called IMRAB 3 TF (the 3 designates a 3-year vaccine and TF stands for “Thimerosal free”). There is also a 1 year version, IMRAB 1 TF. Fort Dodge makes a Thimerosal free rabies vaccine called RABVAC 3 TF. And more Thimerosal-free vaccines may appear in the future.

That’s good news, right? Well, not exactly. It seems that there’s a little-known vaccine ingredient called an excipient. These substances are used in the production of vaccines, but aren’t an actual ingredient that’s directly added to the vaccine.

Know where this is going? That’s right……. your Thimerosal free vaccine probably still has Thimerosal in it. But because it wasn’t added directly to the vaccine, but used in production, the vaccine manufacturers can claim the vaccine is Thimerosal-free!

And this isn’t just true for veterinary vaccines. According to the CDC, there are more than a few human vaccines marketed as mercury-free that actually do have Thimerosal in them (less than 3mcgs per vaccine, but still dangerous to human health).

You can ask for the manufacturer’s data sheet for the vaccine and phone the manufacturer and ask them to email you a list of vaccine excipients before you allow your vet to give that vaccine. But will you get the truth? Don’t count on it. Manufacturers can claim “proprietary confidentiality” when it comes to vaccine ingredients and even the FDA may not know what’s in them. Thimerosal-free vaccines may certainly be a better option than their counterparts – but the sad reality is this is nothing more than a guess. Consumers, and even the FDA, have no way of knowing if that vaccine truly is free of this dangerous neuro-toxin.