Mercury in Immunizations: The Prickly Panacea of the Flu Shot

                                                   

Thimerosal: C₉H₉HgNaO₂S  (123rf.com)

Ever since the late Eighteenth-century English scientist Edward Jenner created the first effective vaccine (against smallpox), scientists have searched for more vaccines to inoculate patients against what they would later understand to be viruses. Modern distribution and manufacture of vaccines requires a reliable preservative to reduce the risk of microbial contamination of them. Vaccines that are left to fester unpreserved would, in turn, infect with diseases the very population they try to protect in the first place. In the early 1930’s, pharmaceutical company Eli Lilly, marketed a new preservative under the name Merthiolate, which later became widely known as Thimerosal after it supplanted other preservatives as the best choice for vaccine preservation. Thimerosal, a compound made from mercury, is an effective antimicrobial agent against a wide range of bacteria and fungi. Thimerosal contains 49.6% mercury by weight (Marques 2007). Despite obvious concerns with taking in doses of mercury, a deleterious neurotoxin, the Centers for Disease Control and Prevention states that, “The medical community supports the use of Thimerosal in influenza vaccines to protect against potential bacterial contamination of multi-dose vials” (CDC).

The CDC may indeed be correct in its support Thimerosal, considering it has more than 70 years of history in use as a vaccine preservative. But, when considering the toxicity of the mercury component that it contains, those who want to ask more questions about its safety might not get simple answers. Consider mercury’s toxicity to humans. Mercury (Hg) is the only metal that is found in liquid form at room temperature. It also vaporizes easily at room temperature, making it easily inhalable. Due to its lipid solubility, it can easily enter the bloodstream through the alveoli and gets quickly picked up by the red blood cells. When exposed to mercury in this manner, small amounts persist in the body for years, and it can damage the central nervous system. Mercury can also damage the brain, liver, cause attention problems, hearing and sight difficulties (or total loss), loss of balance, slurred speech, and even cause death. Symptoms of mercury poisoning are often mistaken for more common illness, due to non-specificity of symptoms. Even more alarming is that the way it acts in humans is “in many ways still a mystery” (Lee, 2010).

In one particularly tragic instance in 1996, Karen E. Wetterhahn, a professor of chemistry at Dartmouth College, and founding professor of that institution’s Toxic Metals Research Program, died when exposed to only a few microliters of a mercury compound. She exhibited the aforementioned symptoms, and spent the last few months of her life thrashing about in an unconscious state in her hospital room. It took five months after exposure for the symptoms to begin, and died less than a year later, despite ongoing aggressive treatment (a tribute to Wetterhahn).

Just as worrisome, is the fact that through environmental pollution, humans regularly receive exposure to mercury in their diets and environments. Coal burning power plants, a primary source of pollution, release mercury into the atmosphere, which in turn, helps the atmospherically suspended mercury to eventually finds its way in the world’s bodies of water. The levels of mercury in the oceans are creating a health risk to those who include fish in their diets. On one hand, the government (FDA) recommends that fish replace fatty meats at least twice per week in Americans’ diets to reduce the risk of heart disease, and yet the same body warns of another threat, the potential to accumulate high levels of mercury in the body through too much consumption of fish. The United States Food and Drug Administration recommends only twelve ounces of fish per week, and even fewer ounces, for some fish, such as shark, tilefish, and some tunas, for pregnant women and children (FDA).

When it comes to vaccines, their effectiveness is hardly in question. Refusing a flu vaccine, for example, puts one at a greater peril of contracting disease than from an allergic reaction resulting from the small amount of mercury compound taken into the blood. The recent false connection between vaccines and autism onto which the public latched its paranoia in recent years has only complicated matters. “Today, in some parts of the United States, vaccination rates have dropped so low that the incidence of certain childhood diseases is approaching levels that existed before effective vaccines became available” (Straub, 2006).

The question is, why take mercury at all, if given a choice? Although the relationship between autism and mercury compounds (Thimerosal) used to preserve vaccines has been debunked, the toxicity of mercury to humans is undisputed, and thus shouldn’t Thimerosal be avoided, if possible? Evidently, not all medical professionals agree that Thimerosal is worth the risk. Indeed, Thimerosal had already been removed from many vaccines beginning in the 1980’s, especially from those administered to infants. It has not, however, been removed in some vaccines for adults, such as the annual flu vaccine. Single dose, non-preserved vaccines are available, but not in quantities sufficient for the entire population to receive a dose. Research on alternatives, such as Phenol-based preservatives, is in progress. Early trials of vaccines with phenols for cutaneous leishmaniasis, a parasitic skin disease, are proving promising (Mayrink, 2006).

The solution would not be terribly complicated. Avoiding Thimerosal in vaccines would require continued research into developing a wider array of preservatives from which vaccine manufacturers could chose. It would be likely for the public, assuming their awareness of mercury’s toxicity, to prefer vaccines without it, and they could then opt to avoid an unnecessary risk for themselves and their children. Secondly, since preservative-free vaccines (e.g. flu vaccine) are already available, manufacturers could potentially increase production of these doses, and in doing so, would make this a viable solution for everyone.

Vaccine regimens should and will retain their important role in therapy for public health. The safety of them far outweighs their risk, but risks do remain unnecessarily present given the known toxicity of mercury. It is obviously difficult to control the levels of mercury that the population is exposed to from the environment. Perhaps in the future it will not be necessary for anyone to accept the risk of additional, unnecessary mercury accumulation sourced from vaccines.