The U.S. Environmental Protection Agency (EPA) and U.S. Food and Drug Administration (FDA) once again advised pregnant women to curb consumption of fish in order to limit fetal exposures to neurotoxic mercury. This warning raises the baffling query: How can the Centers for Disease Control and Prevention (CDC) justify its recommendations that pregnant women get flu shots which are laden with far more mercury than what’s found in a can of tuna?
The CDC has long answered that nettlesome question with the controversial claim that ethylmercury in vaccines is not toxic to humans. Now, two CDC scientists have published research decisively debunking that assertion. As it turns out, there is no “good mercury” and “bad mercury.” Both forms are equally poisonous to the brain.
The CDC study, Alkyl Mercury-Induced Toxicity: Multiple Mechanisms of Action, appeared last month in the journal, Reviews of Environmental Contamination and Toxicology. The 45-page meta-review of relevant science examines the various ways that mercury harms the human body. Its authors, John F. Risher, Ph.D., and Pamela Tucker, MD, are researchers in the CDC’s Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry.
“This scientific paper is one of most important pieces of research to come out of the CDC in a decade,”
Among the findings of the CDC’s new study:
- Methylmercury, the highly-regulated neurotoxin found in fish, and ethylmercury (found in medical products, including influenza and tetanus vaccines, ear drops and nasal sprays) are similarly toxic to humans. Methylmercury and ethylmercury share common chemical properties, and both significantly disrupt central nervous system development and function.
- Thimerosal is extremely toxic at very low exposures and is more damaging than methylmercury in some studies. For example, ethylmercury is even more destructive to the mitochondria in cells than methylmercury.
- The ethylmercury in thimerosal does not leave the body quickly as the CDC once claimed, but is metabolized into highly neurotoxic forms.
Despite this stark rejection of a decade of CDC safety assurances, CDC’s public relations machine is still bucking the new scientific consensus; the article concludes with a telling disclaimer in the tiny font:
“The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Agency for Toxic Substances and Disease Registry.”
CDC’s website continues to feature now discredited safety assurances.
“Baldly dismissing the danger to humans from ethylmercury, has long been a reckless gambit,” said J.B. Handley, a Portland, Oregon, businessman who believes that his son received debilitating injuries from a mercury vaccine.
“With this study, by its own scientists, the CDC has now edged into the realm of criminal endangerment.”
Handley, the founder of Generation Rescue, a vaccine safety advocacy group, condemns the CDC for misleading the medical establishment.
“The CDC knows that pediatricians and physicians rely on its public pronouncements when they make treatment decisions for their patients; how can we escape the conclusion that the agency is knowingly causing the poisoning of tens of millions of American children,” Handley stated.
For example, CDC’s web page still parrots the now discredited industry canard that:
“Thimerosal contains ethylmercury, which is cleared from the human body more quickly than methylmercury, and is, therefore, less likely to cause any harm.”
However, the new study makes the opposite conclusion:
“Thimerosal is quickly metabolized in vivo (in a living organism) due to its reactions with protein and non-protein thiols … so the effects of thimerosal reported in numerous articles are very likely the result of exposure to the metabolite ethylmercury.”
Ignoring the agency’s own scientific evidence, the CDC’s web page stubbornly insists that the “two types of mercury to which people may be exposed—methylmercury and ethylmercury—are very different.” The new CDC study directly contradicts this assertion, “There are many commonalities/similarities in the mechanisms of toxic action of methylmercury and ethylmercury …”
The study meticulously details identical toxicity pathways shared by both forms of mercury:
- Both ethyl and methyl mercury cause DNA damage or impair DNA synthesis (Burke et al. 2006; Sharpe et al. 2012; Wu et al. 2008).
- Both cause oxidative stress/creation of reactive oxygen species (Dreiem and Seegal 2007; Garg and Chang 2006; Myhre et al. 2003; Sharpe et al. 2012; Yin et al. 2007).
- Both decrease glutathione activity, thus providing less protection from the oxidative stress caused by MeHg and EtHg (Carocci et al. 2014; Ndountse and Chan (2008); Choi et al. 1996; Franco et al. 2006; Mori et al. 2007; Muller et al. 2001; Ndountse and Chan 2008; Wu et al. 2008).
- Both cause effects on cell division by damaging the spindle apparatus during mitosis (Burke et al. 2006; Castoldi et al. 2000; Gribble et al. 2005; Kim et al. 2007; Ou et al. 1999b; Machaty et al. 1999; Rodier et al. 1984).
- Both MeHg and EtHg bind to the amino acid cysteine (Clarkson 1995; Wu et al. 2008).
- Both MeHg and EtHg strongly inhibit the reacylation of arachidonic acid, thus inhibiting the reincorporation of this fatty acid into membrane phospholipids (Shanker et al. 2002; Verity et al. 1994; Zarini et al. 2006).
- Both cause an increase in NOS, causing an overproduction of NO (Chen et al. 2003; Chuu et al. 2001; Shinyashiki et al. 1998).
- Both disrupt glutamate homeostasis (Farina et al. 2003a, b; Manfroi et al. 2004; Mutkus et al. 2005; Yin et al. 2007).
- Both alter intracellular calcium homeostasis (Elferink 1999; Hare et al. 1993;Kang et al. 2006; Limke et al. 2004b; Machaty et al. 1999; Marty and Atchison1997; Minnema et al. 1987; Peng et al. 2002; Sayers et al. 1993; Sirois and Atchison, 2000; Szalai et al. 1999; Tornquist et al. 1999; Zarini et al. 2006).
- Both cause effects on receptor binding/neurotransmitter release involving one or more transmitters (Basu et al. 2008; Coccini et al. 2000; Cooper et al. 2003; Fonfria et al. 2001; Ida-Eto et al. 2011; Ndountse and Chan 2008; Yuan and Atchison 2003).
“This study is a nuclear bomb detonating over the CDC,” Boyd Haley, chairman emeritus of the University of Kentucky Chemistry Department, said. “It should be getting international, front page headlines.”
As one of the world’s leading authorities on mercury toxicity, Haley observed, “It’s a momentous rejection of a widely held medical orthodoxy dictating policy changes even more significant than the medical establishment’s reversals on thalidomide, calomel tooth powder, x-rays during pregnancy, or lead exposure to children. In each of these cases, thousands of children were injured or killed before an entrenched medical establishment was finally willing to abandon treatments that were unquestionably causing great harm.”
Ethylmercury vs. Methylmercury in Mass Poisonings
The revolutionary conclusions of the new CDC study actually reflect decades of work by mainstream independent scientists outside the agency. A rich scientific literature that emerged from accidental poisoning events has consistently documented—despite CDC’s official claims—that ethylmercury and methylmercury are equally toxic. In addition to the well-known Minamata and Iraq methylmercury-poisoning, many other large-scale food poisonings have occurred involving ethylmercury fungicides in Iraq in 1956 and 1960, in Pakistan in 1961, and in Russia in the 1960s as well. These episodes resulted in maladies ranging from basic tissue injury to heart and brain injury and even death.
Derban reported in 1974 on 144 cases of mercury poisoning from the use of ethylmercury fungicide on a southern Ghana state farm. Multiple other studies based on these poisoning events showed, as stated in a 1977 study by David Fagan, that the long-term neurological consequences produced by the “ingestion of either methyl or ethyl mercury-based fungicides are indistinguishable.”
A 1979 case report concerned a fifteen-year-old boy who had eaten the meat of a pig that had fed on ethylmercury fungicide−treated seed. Documented effects on the boy included debilitating brain damage and loss of coordination, with high toxicity for the brain as well as the spinal motor neurons, peripheral nerves, skeletal muscles, and heart muscle. The boy died about one month after becoming ill.
Ethylmercury’s use as a pesticide was eventually banned in many countries, including the United States and those in the European Union, and for good reason: A 1977 study gauged ethylmercury chloride’s relative toxicity as a pesticide as the fifth most toxic of thirty substances tested, with a score of 12.7. That grade score almost matched that of DDT, at 14.2, an infamous pesticide banned in 1972.
In 1977 Fagan reported on 13 children suffering from exomphalos (a rare abdominal wall defect that allows the intestines to protrude from the abdomen) treated with gauze soaked applications of thimerosal to prevent infection. Of thirteen patients treated with thimerosal, 9 died. The authors tested mercury levels in the tissue of 8 of the children who died. They reported that “blood and tissue levels of mercury well above the threshold at which damage occurs in all other age groups, it is extremely unlikely that these infants escape neurological damage, which may be subtle.” One infant exposed to thimerosal and survived was later reported as being “restless, easily distracted, and not interested in schoolwork.” The authors recommended that “organic mercurial antiseptics should be heavily restricted or withdrawn from hospital use, as the fact that mercury readily penetrates intact membranes and is highly toxic seems to have been forgotten.”
Why Does the US EPA only Provide Guidelines for Exposure to Methylmercury and not Ethylmercury?
In 1995, based on research from outbreaks of poisonings and other research from the Faroe Islands and the Seychelles, the EPA established a safe “reference dose” for methyl mercury(RfD). An RfD is defined as “an estimate of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of adverse effects when experienced during a lifetime,” according to the EPA.
The EPA adopted for methylmercury an RfD of 0.1 microgram of mercury per kilogram of the individual’s body weight per day. Other health agencies set their own recommended limits for methylmercury exposure, including the FDA in 1979, the World Health Organization in 1989 and the US Agency for Toxic Substances and Disease Registry (ATSDR) in 1999. The highest of these limits was the WHO’s, at 0.47 microgram per kilogram of body weight per day.
In 1999 the US Congress directed the EPA to contract with the nonprofit, independent National Research Council (NRC) to prepare recommendations on an updated and appropriate RfD. The EPA commissioned the National Academy of Sciences (NAS) and the NRC to carry out a study on toxicological effects of methylmercury compounds. The goal was to review the process used by the EPA to establish national safety standards. The committee evaluated the literature, which demonstrated methylmercury compounds’ high toxicity to brain tissue, even at minute levels. The NAS ultimately agreed with the EPA‘s originally conceived RfD, which remains in place today. An RfD has never been established for ethylmercury.
The CDC has crossed ethical and perhaps even legal boundaries by purposefully blocking efforts by the National Institute of Environmental Health Science’s (NIEHS) National Toxicology Program (NTP) to test ethylmercury for toxicity – a process that would have lead to maximum exposure guidelines. In 2000, the FDA nominated thimerosal to the NTP for toxicity testing. However, CDC officials derailed the review telling the NTP committee that “There is a great concern within CDC about continued attacks from anti-vaccine groups questioning the integrity of CDC activities and recommendations regarding the use of a thimerosal-containing vaccine.” In response to CDC pressure, the NTP put thimerosal on a permanently deferred status. Thimerosal has, therefore, never been tested for safety or toxicity.
Ethyl Mercury Exposure Levels Based on Methyl Mercury Guidelines
A single Thimerosal-preserved flu vaccine contains 25 micrograms of ethylmercury. If the EPA RfD for ingested methylmercury is applied to this injected ethylmercury figure, an individual would have to weigh more than 250 kilograms (551 pounds) for the 25 microgram exposure to be considered safe. Back in the 1990s, a two-month-old child could have received 62.5 micrograms from three vaccines in a single doctor’s visit. Assuming the child weighed about 5 kilograms (11 pounds), he or she would have received 125 times the EPA RfD for methylmercury.
At least one study has suggested that the methylmercury RfD should be set lower for infants and also for fetuses. In 1995, Steven Gilbert and Kimberly Grant-Webster wrote:“Available information on the developmental neurotoxic effects of MeHg [methylmercury], particularly the neurobehavioral effects, indicates that the fetus and infant are more sensitive to adverse effects of MeHg. It is therefore recommended that pregnant women and women of childbearing age be strongly advised to limit their exposure to potential sources of MeHg. Based on results from human and animal studies on the developmental neurotoxic effects of methylmercury, the accepted reference dose should be lowered to 0.025 to 0.06 MeHg [microgram]/kg/day.”
What might this mean for a fetus today? We’ll take the low end of that estimate and apply it to an average 1.15-kilogram (2.54-pound) fetus at the start of the third trimester. A fetus exposed to 25 micrograms of mercury via a Thimerosal-preserved flu shot administered to its pregnant mother could be subject to 870 times the proposed lower reference dose.
Mainstream Science Suggests Ethylmercury is More Toxic than Methylmercury
New and old research support the caveat that “safe” levels of ethylmercury exposure might indeed be dramatically lower than the EPA’s RfD. A 2012 Italian study, for instance, showed that ethylmercury-containing Thimerosal diminished the viability of human cells in the lab at a concentration one-fiftieth that of methylmercury. By this measure, ethylmercury is 50 times as toxic as methylmercury to humans.
Japanese research on rats in 1968 showed that ethylmercury compounds, such as ethylmercuric chloride from which Thimerosal is made, clear the body more slowly than other mercury compounds including mercuric chloride and phenylmercuric chloride.
A book chapter in 1972 by Staffan Skerfving, an emeritus professor at Lund University in Sweden, reviewed the literature on methylmercury versus ethylmercury, noting several instances where compounds of the latter appeared more toxic than the former in animal studies.
For example, ethylmercury chloride killed off half of a test population of mice—a classic “LD50” (lethal dose) study—within a week at a concentration of 12 milligrams of mercury per kilogram of body weight; methylmercury chloride’s LD50, meanwhile, lethal to half the mice was 14 milligrams. This study suggested that ethylmercury was twice as toxic.
Further examples abound. Pig studies by Tryphonas and Nielsen in 1973 showed that ethylmercury “proved much more toxic” than methylmercury. Meanwhile, another 1973 study that emerged from a 1971 international conference found the toxicity of ethylmercury compounds comparable to or even greater than that of methylmercury, as well as more persistent in the brain.
An advisory committee at the conference reported that the International Committee on Maximum Allowable Concentration for Mercury and Its Compounds grouped ethylmercury with methylmercury, and observed that accounts of human intoxication with ethylmercury have usually described neurological and other symptoms similar to those of methylmercury. The report noted that in studies of patients transfused with a commercial product of human plasma containing 0.01 percent Thimerosal, as well as in studies of mice injected with an ethylmercury solution, the increased level of inorganic mercury added to the mercury already existing in the body resulted in a “longer biological half-life of total mercury than that reported for methylmercury injection.”
Why do the CDC and WHO Report that Ethylmercury Exposure is Safe?
The WHO’s conclusion that ethylmercury is safer because of its “short” half-life may be based on observations that ethylmercury disappears from blood samples quicker than methylmercury. However, this tendency may be evidence not of ethylmercury’s comparative safety, but of its greater danger if, as science has suggested, ethylmercury is not leaving the body but simply migrating more rapidly to the organs, including the brain. Indeed, studies have shown that an ethylmercury compound’s short residence in the blood stems from its ability to more easily pass into the organs, where it can remain for long periods and possibly cause injury.
For example, Blair in 1975 dosed squirrel monkeys with intranasal saline or Thimerosal daily for six months, finding that, compared to the saline group, mercury concentrations in the Thimerosal group were significantly raised in the brain, liver, muscle, and kidney, though not in the blood. Although there were no signs of toxicity in the animals, Blair concluded that the “accumulation of mercury from chronic use of thiomersal-preserved medicines is viewed as a potential health hazard for man.”
Beyond a possibly greater capacity to have inorganic mercury accumulate in organs, Thimerosal also passes more easily from a mother’s bloodstream through the placenta into a developing baby than does methylmercury. That was the evaluation made in a 1983 review study by A. Leonard. In addition, a 1995 study demonstrated that both ethylmercury and methylmercury cause mutagenic changes at similar concentrations in bacterial cells.
The Twisted Saga of Pichichero
With these and other studies as background, an important study in humans took place in the early 2000s. The study, by Michael Pichichero of the University of Rochester Medical Center and published in The Lancet in 2002, lent some apparent scientific credence to the idea that ethylmercury is safer than methylmercury. Pichichero, who helped develop the HiB vaccine and previously received grants and honoraria as a consultant for other vaccine makers, did not declare these conflicts of interest in a statement in his paper, as required by The Lancet’s peer review rules. The Pichichero study assessed mercury levels in the blood, urine, and feces of forty infants ages six months or younger three to twenty-eight days after they had received Thimerosal-preserved vaccines (DTaP, HepB, and in some cases Hib). For comparison, twenty-one similar infants who received Thimerosal-free vaccines were also evaluated. Although infants who received Thimerosal-preserved vaccines had higher levels of mercury in their blood, urine, and feces than did the infants who received Thimerosal-free vaccines, the authors concluded that the levels of mercury detected were not greater than what is considered safe. Most of the mercury from the injected Thimerosal seemed to have left the children’s bloodstreams more rapidly than methylmercury found in the blood of those eating fish in previous studies; the researchers estimated a half-life of seven days for ethylmercury in the blood. Pichichero concluded that ethylmercury, therefore, did not remain in children’s bodies long enough to possibly cause damage.
Pichichero’s study immediately came under attack by internationally respected scientists in a 2003 letter to The Lancet by Neal Halsey, of the Institute for Vaccine Safety at Johns Hopkins Bloomberg School of Public Health, and Lynn Goldman, also of the Bloomberg School of Public Health. Halsey and Goldman pointed out that Pichichero and colleagues “did not measure the peak blood concentrations that occurred within hours after the injections.” The concentration listed for one child in the study of 20.55 nanomoles per liter was obtained five days post-vaccination. Assuming Pichichero’s own estimate of an ethylmercury half-life in the blood of seven days, the peak blood concentration for this child was 29.4 nanomoles per liter—exceeding the conventional safety threshold of 29.0 nanomoles per liter, and contradicting the study’s claim that “no children had a concentration of blood mercury exceeding 29 nmol/L.” The child in question had received 37.5 micrograms of ethylmercury rather than the possible maximum exposure of 62.5 micrograms. In the latter scenario, the child’s peak blood mercury concentration would have hit 48.3 nanomoles per liter.
Another child in the study registered a 7 nanomole per liter blood concentration 21 days post-vaccination; extrapolating backward, this child’s peak mercury level might have reached 42 nanomoles per liter. Halsey and Goldman’s letter further pointed out that Pichichero seemed to have cherry-picked the children in the study—some already with no margin of safety for further mercury exposure—seemed to have come from a population with low background environmental and maternal exposure to methylmercury.
Soon after the publication of Pichichero’s study, alarming new evidence emerged that ethylmercury lingers in the body. In an unpublished letter submitted to Pediatrics, Dr. Boyd Haley, then-chairman of the chemistry department at the University of Kentuck, and Mark Blaxill challenged Pichichero’s hypothesis that ethylmercury is quickly excreted. Pichichero and colleagues had measured the excretion levels of mercury in the stools of 22 healthy infants exposed to Thimerosal-containing vaccines. Pichichero’s estimated range for the infants aged two and six months was 23 to 141 nanograms per gram of stool (dry weight). Assuming the excretion rate reported by Pichichero, Blaxill and Haley demonstrated that it could take children with low excretion rates of mercury in their stool almost four years to eliminate an 187.5 microgram mercury burden from their bodies.
In 2006, Luis Maya and Flora Luna further debunked Pichichero’s conclusions. The authors pointed out that while Pichichero’s team had found ethylmercury to be excreted in appreciable quantities in the feces, the researchers did not study other body parts beyond the blood, such as the central nervous system. In agreement with Halsey and Goldman, Maya and Luna criticized Pichichero for neglecting to measure the peak serum levels of ethylmercury after the first hours of inoculation, though other investigations had documented substantially elevated blood concentrations in the first 48 to 72 hours after administration in pediatric vaccines. Maya and Luna also pointed out that the study was small and measured variables of pharmacokinetics (the actions of a drug within the body over time), so it was not designed to measure the biological effect of Thimerosal as a preservative.
Pichichero Redux: Yes, Ethylmercury Rapidly Leaves the Blood, but Not the Body. It Lodges in the Brain!
By then, other research had clarified that, while ethylmercury disperses quickly from the bloodstream, this is not evidence of safety. For example, a 2004 study by G. Jean Harry of the National Institute of Environmental Health Sciences noted that mice injected with Thimerosal accumulated mercury in both the brain and kidneys. “By seven days” post-treatment, the study authors wrote, “mercury levels decreased in the blood but were unchanged in the brain” compared to levels measured just 24 hours after treatment, indicating slow clearance.
The landmark study in this regard was conducted by the University of Washington’s Thomas Burbacher and published in 2005. The researchers compared mercury levels in the blood and brains of infant macaques injected with Thimerosal-containing vaccines with monkeys who ingested equal amounts of methylmercury hydroxide via a feeding tube. The former group of primates were exposed to 20 micrograms of ethylmercury per kilogram of body weight on the day they were born and when they were seven, 14, and 21 days old, which was estimated to be within the range of doses that children at different developmental stages were receiving in the United States. The dosing methods were selected to mimic the routes of exposure in humans who eat mercury-containing foods and receive mercury-containing vaccines.
Subsequent tests showed a faster disappearance of mercury from the bloodstream of Thimerosal-injected monkeys than from the methylmercury group. Total mercury amounts in the brain were also threefold less for the Thimerosal-treated monkeys. However, the Thimerosal-injected monkeys had a higher ratio of brain-to-blood levels of mercury than the methylmercury group. In general, the primates injected with Thimerosal in the Burbacher study retained twice the level of inorganic mercury—a breakdown product of Thimerosal that has been suggested to be responsible for the brain damage associated with methylmercury—in their brains as the methylmercury-exposed primates. While all seventeen monkeys given Thimerosal had “readily” detectable levels of inorganic mercury in their brains, only nine of the seventeen exposed to methylmercury had detectable levels. Burbacher cited previous research ranging the half-life of inorganic mercury in various brain regions of primates from 227 to 540 days. In either case, that is a long time period for the toxic element to remain, especially if at higher levels from ethylmercury deposition versus methylmercury.
Burbacher and his colleagues wrote in summary that “[methylmercury] is not a suitable reference for risk assessment from exposure to thimerosal-derived [mercury]” and that: Data from the present study support the prediction that, although little accumulation of [mercury] in the blood occurs over time with repeated vaccinations, accumulation of [mercury] in the brain of infants will occur. Thus, conclusion [sic] regarding the safety of thimerosal drawn from blood [mercury] clearance data in human infants receiving vaccines may not be valid, given the significantly slower half-life of [mercury] in the brain as observed in the infant macaques.
A more recent 2012 study by Croatian researchers took a similar approach as Burbacher’s study but in suckling rats. That study also discredits CDC’s claims of ethylmercury’s comparative safety. Maja Blanusa and colleagues gave rat pups either Thimerosal or inorganic mercury three times in their first 11 days of life, mimicking human infant vaccination schedules. The scientists then assessed the total retention of mercury and excretion over six days. The Thimerosal-exposed rats showed higher mercury retention rates in their brains. Furthermore, these Thimerosal-exposed rats exhibited similar fecal excretion and much lower urinary excretion compared to the inorganic mercury-exposed rats. That second group also demonstrated higher retention rates of mercury in organs other than the brain.
Two additional studies in the last few years by researchers in Brazil and Germany show, again, that methylmercury, in particular, should not be considered summarily more dangerous than ethylmercury. The studies found that cells similarly take up both forms of mercury. The former, by Luciana Zimmermann and colleagues, showed in 2013 that the methyl- and ethylmercury entered cultured rat cells in roughly equal measure and display similar toxicities. The 2014 German study led by Christoph Wehe used novel laboratory techniques in concluding that methylmercury and ethylmercury in the form of Thimerosal accumulated in equal measure in a type of cultured human neural cell.
Overwhelmingly, the literature presents clear evidence that ethylmercury is invasive and persistent in the brain. Emerging evidence suggests that ethylmercury is more toxic than methylmercury, in direct contrast with the CDC’s historic position. It’s time for CDC’s public relations department to catch up with mainstream science. Since the World Health Organization (WHO relies mainly on CDC’s vaccine safety science, the CDC’s unscientific pronouncements endanger, not just U.S. children, but hundreds of millions of children around the world. Knowing what we now know, the U.S. Federal agencies and the WHO should follow the precautionary principle and phase out the use of thimerosal in all medical products, including vaccines.