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Home » Christopher Exley & aluminum adjuvants in vaccines – scientific critique

Christopher Exley & aluminum adjuvants in vaccines – scientific critique

Last updated on October 1st, 2019 at 11:10 am

This article examines a recent commentary letter titled “An aluminium adjuvant in a vaccine is an acute exposure to aluminium” by Christopher Exley (Keele University, UK). Although the author may have several valid points, the presence of several logical flaws and the selective citation of the existing literature related to aluminum adjuvants safety is a concern, especially in times in which vaccine hesitancy and refusal have been defined by the World Health Organization as a global threat in 2019.


The first item of concern written by Christopher Exley is

For example, paediatricians, responsible for administering the vaccine schedule for children, seem in particular, to be uninformed about the properties of aluminium adjuvants and their mode of action in vaccines.

The rationale of such comment appears unfounded and not supported by the literature. For instance, the American Association of Pediatrics, the most influent association of pediatric physicians in the United States, provides an easy and accessible fact-sheet to physicians. Such information is also available on certain medical centers websites such as Children Hospital of Philadelphia. I would speculate that similar information is readily available from other societies.

This sentence was immediately followed by a quote criticizing physicians “This apparent ignorance of the published scientific literature is unexpected in those charged with the wellbeing of neonates and infants and especially in the light of Janeway’s description of alum adjuvant as ‘the immunologist’s dirty little secret’.”

However, that sentence was cited out of the context from the original article. In the original article, Janeway referred to this quote as part of a paragraph discussing the use of adjuvants and the lack of a mechanistic explanation for their activity, referring to it as the following:

…however, in order to obtain readily detectable responses to these antigens, they must be incorporated into a remarkable mixture termed complete Freund’s adjuvant, heavily laced with killed Mycobacterium tuberculosis organisms or precipitated in alum and mixed with Bordetella pertussis organisms. I call this the immunologist dirty secret.

The quote of Janeway by the author is both taken out of context and irrelevant to the use of adjuvants by pediatricians.

I would also raise my concerns of the condescending connotations of Christopher Exley towards a class of medical professionals known for their remarkable effort and dedications to ensure the health and wellbeing of infants and children. By using metaphorical terms such as “baby talk” in a derogatory manner towards a whole professional corpus in general, in an attempt of infantilizing their communications and knowledge on the topic of immunization.

Exley is dangerously using a slanderous claim that has no place in a scientific journal. I may mention that similar attack to a criticism of a scientific study co-authored by Exley, led to the retraction of one of his letters to the editor, as it was deemed too slanderous.

Although cases of retractions for studies is common practice, in my own experience the notice of retraction of letters to editors remains a rare event indicative of severe misconduct from the authors. I have serious concerns about the ability of Christopher Exley to withstand the criticism of his work and maintaining objectivity in his studies and commentary letters, including this current publication.

There’s more aluminum in this can of coke than in vaccines. Photo by Mae Mu on Unsplash

How much aluminum is found in vaccines

In the following section, Exley is discussing the content of aluminum in vaccines, claiming an alleged inaccuracy of the aluminum content as an amount (weight) per unit volume of a vaccine:

Currently about 20 childhood vaccines include an aluminium adjuvant. Vaccine industry literature (for example) expresses the aluminium content of an individual vaccine as an amount (weight) of aluminium (not aluminium salt) per unit volume of a vaccine (usually 0.5 mL). Industry does this to account for the fact that there are no strict molecular weights for the polymeric aluminium salts that are used as adjuvants in vaccinations.

Exley stated that the amount of aluminum in vaccines is not accurate, claiming the following

This is not explained in the literature they provide with vaccines and can cause confusion for some as the actual weight of hydrated aluminium salt (e.g. aluminium oxyhydroxide, aluminium hydroxyphosphate and aluminium hydroxyphosphatesulphate) in any vaccine preparation is actually approximately ten fold higher.

Such a statement is confusing at best, or a blatant violation of the tenet of “law of mass conservation” taught in any public high school chemistry class.
Let’s use the example from the author

GlaxoSmithKline’s Infanrix Hexa vaccine is reported by the manufacturer to contain 0.82 mg of aluminium per vaccine (0.5 mL). Thus, the weight of aluminium salt in this vaccine is approximately 8 mg, which is approximately ten times the weight of all of the other components of the vaccine when combined.

The amount of aluminum mentioned is inclusive of all the different chemical species mentioned by the author (and by which I will let his expertise about the chemistry of aluminum on his behalf, as I have no credentials in that matter), as the amount of total aluminum is indeed 0.82mg per 0.5mL (or 1.64mg per mL).

A central tenet of high school chemistry is the concept of molarity. There is a substantial advantage of molarity to estimate a quantity of a chemical over the use of mass. If we consider it for our example (1.64mg/mL), the molarity of aluminum in Infanrix Hexa would be 60 mmole/mL. That would represent a molecular mass of 2.7mg/mL, and 14.1mg/mL for aluminum oxyhydroxide, hydroxyphosphate, and hydroxyphosphate sulfate. Different amounts (in mass) but the absolute same amount of aluminum (Al).

These compounds all contain one aluminum in their formula; therefore, the actual amount of aluminum would remain 0.82mg/0.5mL, regardless of being in its oxyhydroxide, hydroxyphosphate or hydroxyphosphate forms.
A salt can have the same molarity and yet have a different amount (mass) dissolved in a defined volume.

A common example I have been facing is the use of magnesium sulfate (MgSO4) in the preparation of a buffer solution for the isolation of primary rat astrocytes. Two forms of MgSO4 can be purchased: an anhydrous form, or a hydrated form (MgSO4, 7H2O). The latter being preferred due to its higher dissolution rate. A preparation of a MgSO4 (MW=120.36g/mol) solution titrating 1 mole/L can be obtained by dissolving 120.36g of anhydrous form, or by dissolving 246.36g of the hydrated form.

If we apply the logical reasoning of the author, we should consider that the MgSO4 solution prepared with the hydrated form should contain twice more Mg ions because the weight of the hydrated is twice of the anhydrous form. Such an assumption is in clear violation of the law of mass conservation as the amount (in moles) of Mg present in solution is strictly equal, whether it is anhydrous or hydrated.

In order to make his statement valid, the author has to provide evidence to support his claim by citing the literature or by direct experimental evidence that the “10-fold higher” amount of aluminum is reflected by a 10-fold increase in molarity as well.

A second violation of scientific fact relates to the pharmacokinetics of aluminum. Vaccines are commonly administered as intramuscular (IM) or subcutaneous (SC) injection. In pharmacokinetics, these two administration routes are commonly referred to as extra-vascular routes, with the vascular routes restricted to intra-arterial (IA) and intravenous (IV) administration.

Pharmacists and physicians are exposed to pharmacokinetics during their professional training. Yet, in the following statement, the author made a statement that is clearly in contradiction with a well-established fact of pharmacokinetics:

All 8 mg of the aluminium salt (or 0.82 mg of aluminium) will immediately be systemic; it is inside the infant’s body.

Such a statement is not only wrong but also plainly fallacious. By definition, the immediate release of a drug within the systemic circulation is only achieved by its administration via IV bolus, in which the maximal concentration (commonly referred as C0) is achieved immediately following injection, such concentration being tributary of the dose administered (mass) and the volume of distribution (volume).

If we assume an IM injection, we have to apply the constraint related to extravascular routes, with an added constraint of the density of the skeletal muscle tissue coupled with its relatively low blood perfusion rate. Therefore, the amount of a drug injected via IM will be tributary of its bioavailability.

Commonly, aluminum adjuvants have been documented to display a very low bioavailability resulting in a slow-release from the injection site to the systemic circulation. Such slow release process results in a mild peak concentration, and subsequent levels of circulating aluminum detected in plasma similar to saline controls (or to the vaccination status), as reported in different studies including the pharmacokinetics of aluminum adjuvants in rabbits, in rats, and in humans (see this and this which was reviewed here). These studies all concluded that aluminum adjuvants, as found in vaccines for pediatric usage, were not showing a concern of elevated systemic levels of aluminum and therefore mitigate the concern of toxicity linked to aluminum adjuvants.

Even using a fast-dissolving aluminum salt (such as aluminum citrate), Weisser and colleagues reported a tmax of 5 minutes in their study. These study, along with another study from Weisser and another from Movsas all concluded that aluminum adjuvants, as found in vaccines for pediatric usage, were not showing a concern of elevated systemic levels of aluminum and therefore mitigate the concern of toxicity linked to aluminum adjuvants.

Surprisingly, these references, albeit crucial for such commentary about aluminum adjuvants, have been omitted for citation by the Exley.

Closing remarks on Christopher Exley and aluminum

I will not further continue my rebuttal, as Christopher Exley has displayed within the first part of his commentary a bias against vaccine safety. It is also noteworthy that concerns about aluminum safety in vaccines was not documented in the literature before 2007, coinciding with the decline of the “MMR-autism” hypothesis initially proposed by Andrew Wakefield only to be refuted by the retraction of his study from The Lancet, and refuted by several epidemiological studies documenting no evidence of increased autism rate following MMR immunization.

The unprobeable association of vaccines with “vaccine injury” is a common trope from the anti-vaccination proponents, in particular by attempting to generalize the “MMR-autism” link to all vaccines.

In their common argument, such movement often cites an ingredient as a damage-causing agent, resulting in an important reaction from the scientific community to demonstrate the absence of toxicity of this ingredient, only to have the concern shifted to another ingredient. A century ago, the use of cow pus as a method to vaccinate against smallpox was an argument used by the anti-vaccination movement. It shifted through the last decade to formaldehyde, thimerosal, aluminum and more recently to polysorbate 80.

The article, with all my respect to Christopher Exley, is a gross and scientifically inaccurate review of the existing literature in regards of aluminum adjuvants in vaccines, flawed by logical flaws, lack of scientific literature supporting the bold statements made by the authors. Such inaccuracy and bold statement are summarized in the introductory sentence of the final section:

Simply by looking at just one dose of a vaccine given at 8 weeks of age it is abundantly clear that science does not support this contention, as espoused regularly by many infant paediatricians.

The lack of citations of contemporary scientific literature makes me question the validity of the claims made, as well as the facts presented in this commentary.

It only took one fraudulent paper to lead to the resurgence of measles and other vaccine-preventable diseases within the last 20 years. Such resurgence is clearly documented in the United States. In 2000, measles was considered eliminated. Yet, the erosion of the immunization rate during that period led to three major outbreaks within the last 5 years, including 2014 and 2018. As of today, the number of cases reported for 2019 represents the highest number of cases since 1992.

By perpetuating myths and fallacies, and giving scientific merit to such items by allowing alarmist commentaries based on a scientific literature not aligning to the scientific consensus such as this commentary from Christopher Exley, we are giving a false equivalence to a fringe and minuscule movement within the field, and involuntarily fanning the fire of vaccine hesitancy and contribute in the decrease of immunization rate significant enough to be identified in 2019 as a global health threat.

In conclusion, as a scientist, I am formally raising concerns over the claims made by Exley in this commentary and therefore request that the author demonstrate evidence of the claims made.


This article is by VaultDwellerSYR, a pseudonym used by a faculty member of a School of Pharmacy within a large medical school. They have significant research and publications in the effect of certain chemicals on the brain. Although we are opposed to all arguments from authority, the author has a substantial record actual, published research into this field. 

The author has stated that he has no conflict of interests to disclose.


Michael Simpson

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