top of page



MBT is a necessary vulcanization catalyst in the manufacture of natural rubber used worldwide for syringe plunger seals, pharmaceutical ampoule seals, unit-dose syringes or cartridges and in 3 parts of IV infusion sets. These articles reveal that, as an injection contaminant, it becomes bound to plasma proteins and thus forms an IgE allergen and a cumulative toxin. In April 2013, the WHO’s International Drug Reaction Monitoring Centre, in a review of “The Nurses are Innocent,” stated that this “important book”….. “reveals the systemic failure of government health protection agencies to protect citizens from a known allergenic and toxic chemical, MBT, a worldwide contaminant of injections for 30 years, with medical journals aiding and abetting the process by refusing to publish informative articles on public health issues related to MBT contamination.”
Hazards of natural rubber’s MBT and latex contact in injections (vaccines and many other instances)

Military Medicine, January 2021, Vol. 186, 38-39.

Dr. Davenport’s response to my letter regarding her article: Latex content in adult vaccines suggested, incorrectly, that the toxic and allergenic natural rubber contaminant, MBT, also affected synthetic rubber substitutes, requiring me to correct that misinformation.
Toxic, allergenic MBT in adult vaccines

Military Medicine, May 2020, Vol. 185, 7-8.

Not latex, but MBT, a toxic, allergenic contaminant leaching from syringe and drug ampoule rubber, is the major cause of serious and fatal reactions to vaccines. Safe synthetic rubber has been available for decades [WHO Uppsala Reports, Book review (April 2013), "The Nurses are Innocent"].  All injectable drugs in contact with natural rubber in the packaging share this danger (Medical rubber anaphylaxis, Lancet 1990).  Japan eliminated MBT rubber from injectable drug packaging by 1985, but inadvertently allowed importation of Sanofi-Pasteur whooping cough vaccine with MBT-rubber contact. Four children died before it was withdrawn.  A large fatally flawed statistical study of reactions to a new, "non-ionic"  expensive angiographic-radiographic radiopaque x-ray dye showed significantly fewer serious side effects compared to the older, cheaper "ionic" dyes. However, Japanese syringes and ampoule seals used safe synthetic rubber, whereas the rest of the world used disposable syringes and the inexpensive ionic dye ampoules with MBT-rubber seals. FDA)statistics revealed that after USA eliminated pharmaceutical MBT-rubber, in 1990, similar numbers of severe reactions occurred using the two dye types.
An Expensive New X-ray Dye, Shown by Statistics to Reduce Serious Side Effects

Chapter 9: The Nurses are Innocent – The Digoxin Poisoning Fallacy, Dundurn Press, 2011

This describes in detail how a biased study (Katayama, Radiology 1997) falsely showed a new urographic-angiographic class of non-ionic radiopaque contrast agents was much safer than the older much less expensive ionic contrast agents. This resulted in a worldwide shift to new expensive non-ionics, adding much cost to world healthcare costs. However, the injected ionics were in contact with natural rubber, whereas non-ionics were not. MBT leaching from natural rubber parts of X-ray dye syringes and ampoules are a known cause of IgE anaphylaxis. FDA statistics showed that, after 1990, ionics and non-ionics had similar incidences of severe reactions.
Control of Medical Journal Content

Chapter 8: The Nurses are Innocent – The Digoxin Poisoning Fallacy, Dundurn Press, 2011

The pharmaceutical industry, through its financial power and vigorous lobbying, exerts control over academic medical specialists, university professors, and the reviewers, and editors  of medical journals. They can thus control medical journal content.  The pharmaceutical industry is alerted to the content of journal articles at the time of submission, allowing it to block publication if the articles have content unfavourable to drug marketing.  Articles describing adverse effects of pharmaceuticals are difficult – even impossible at times – to get published; this is a factor allowing the known hazard of MBT in medical rubber of syringes, ampoule seals and IV injection sets to persist for over thirty years (WHO’s Drug Monitoring Centre, Uppsala Reports, April 2013).

Controversy Over Ionic And Nonionic Radiopaque Contrast Media

Canadian Association of Radiologists Journal, 1994, Vol. 15: 539-540

A large Japanese study (Katayama Radiology 1990), reported that a new nonionic (low osmolar) iodinated arteriographic contrast agent had significantly fewer serious side effects than  the much cheaper ionics in use around the world, resulting in a large  annual increase in healthcare costs in a safety-related shift to the expensive nonionics. However, the Katayama study was fatally flawed because Japan, uniquely in the world, used an inert synthetic rubber for disposable syringe plunger-seals and for all pharmaceutical ampoule seals (including nonionic ampoules). The older, much cheaper ionics were sealed with natural rubber, known to contaminate ionics with MBT (mercapto-benzothiazole), a rubber-manufacturing catalyst, which binds to plasma proteins, creating a foreign protein  allergen, capable of producing potentially lethal IgE-mediated anaphylaxis. Lasser (Radiology 1997) used FDA statistics that showed that, after 1990 (when the USA had converted to inert MBT-free synthetic rubber for syringe and ampoule seals), serious reactions to ionic and the expensive nonionics were similar. 

The Nurses Are Innocent - COVER STORY

Canadian Nurse, December 1993


The Canadian Nurse, the official journal of the Canadian Nurses Association, has a long history of exploring issues of importance to their profession. In December 1993, Editor-in-chief Heather Broughton recognized the importance of Gavin Hamilton's research into the digoxin fallacy poisoning and not only included his 6-page article as the cover story, but also devoted her editorial page completely to highlighting the importance of this work to the nursing profession.

Medical Rubber Anaphylaxis

The Lancet, Volume 336, Issue 8728, Pages 1453 - 1454, December 8, 1990

This article warns Lancet readers of the continued MBT contamination of medical rubber in contact with injections. Plasma-protein-binding creates  a hapten-protein IgE allergen that causes a foreign protein anaphylaxis (similar to shellfish allergy).  Natural rubber in disposable syringes, ampoule seals and IV administration sets caused potentially toxic MBT levels in 91 Hammersmith Hospital babies. The significant reduction in serious reactions to radiopaque contrast agents for IVP injections in Japan, with a new expensive non-ionic variety is linked to Japanese syringes and ampoule seals being made from non-toxic, non-allergenic synthetic rubber, whereas inexpensive ionic contrast agents in North America were exposed to MBT in the natural rubber seals of syringes and pharmaceutical ampoules. This article’s prediction that, when synthetic rubber replaced natural rubber for medical injection contact, the reactions to non-ionic and ionic contrast agents might become similar, was later proven true;  after 1990, using FDA statistics, Lasser, Radiology, 1997, revealed that the incidence of serious side effects was identical with inexpensive ionic high-osmolar radiopaque contrast agents and the much more expensive non-ionic low-osmolar agents. Suppression of, and/or ignoring, this vital healthcare-cost information has resulted in the continued widespread use of the newer expensive non-ionic low-osmolar radiographic contrast agents.

Contamination of contrast agent by MBT in rubber seals

Canadian Medical Assocation Journal (1987); Volume 136: pages 1020-1021.

In 1983, I substituted MBT-free all-plastic Danish Pharmaplast syringes and, later, Japanese Terumo syringes, which used a safe new synthetic rubber as plunger seals.  Despite these precautions, another cluster of allergic reactions (including anaphylaxis) occurred (1987), Samples of the radiopaque contrast agent tested positive for MBT in 3 different Canadian government laboratories, the MBT leaching from the natural rubber ampoule seals.  Note that, although all natural rubber is made using latex, it was only when  MBT was identified, that the clusters of allergic reactions occurred on two separate occasions in one small private radiology office. Thus, the major allergen in natural rubber must be MBT, not latex. In spite of a worldwide potentially lethal hazard of MBT contamination of injections by natural rubber seals in disposable syringes and ampoules, these are the only 2 reports of MBT-related allergic injection reactions in the world medical literature.  In all other cases of MBT reactions, the anaphylaxis and the deaths were falsely attributed to allergy to the immunization vaccine, the insulin, the dentist’s local anesthetic, etc.

Contamination of contrast agents by rubber components of 50 ml disposable plastic syringes

Radiology (1984), Volume 152, pages 539-540.

Dr. Harry Fisher, an editor of Radiology and a world expert on contrast media reactions, having read the CMAJ article (2, above) asked me to write a similar report for Radiology, for which he would write an accompanying commentary. To his dismay, Dr. Fisher later had to phone me to reveal that Radiology’s editorial board rejected the article. I then contacted the Bureau of Medical Devices, demanding the chemical name of the “phenolic compound”  rhat contaminated my injections.  Dr. Pierre Blais, the biochemist in charge of medical plastics and rubber analysis, confessed that their analysis had found 8 different chemical compounds leaching into the contents of the syringes, three being MBT (mercapto-benzothiazole) compounds. Research revealed MBT was allergenic and toxic, especially intravenously.  Contacting Dr. Fisher with this new information, he asked me to revise the article, send it to his office and he “would attend to this submission, personally!”  Dr. Fisher’s Commentary accompanied this Radiology article. A very troubling question remains: why did  Health Canada’s Bureau of Medical Devices withhold this vital MBT information, putting lives at risk worldwide with any injection using disposable plastic syringes?

Adverse reactions to intravenous pyelography contrast agents

Canadian Medical Association Journal, 1983 Sep 1; 129 (5):405–406

Health Canada’s Bureau of Medical Devices tested a number of my BD Plastipak syringes, rubber parts of which were suspected of causing a cluster of allergic reactions (including life-threatening anaphylaxis).  Dr. Pierre Blais, the Bureau’s expert on rubber and plastics, reported (by phone, only) that all syringes contaminated syringe contents with “a  phenolic compound,” an unusually vague result from a state-of-the art health protection analytical laboratory.  When I phoned the editor of the CMAJ about this cluster of reactions and the rubber contamination, he suggested that I submit a report as a letter. It was published in the September 1, 1983, issue of the CMAJ.


The Lucia de Berk Miscarriage of Justice in The Netherlands


"After the 2011 book, "The Nurses are Innocent” went to press, a similar miscarriage of justice, regarding murder by digoxin poisoning (based on autopsy blood digoxin readings, bad statistical analysis and purely circumstantial evidence), was uncovered in the Netherlands.  Nurse Lucia de Berk had been convicted of murder and sentenced to life in prison. I informed a group of academic Dutch citizens, who had fought vigorously to have the conviction overturned, that the arguments cited in ”The Nurses are Innocent” would apply to the false digoxin poisoning in the de Berk case.  Lucia de Berk was released after spending six years in prison – and after suffering a hemorrhagic stroke and paralysis after her sentence was pronounced by the judge."
"Just who's calling the shots" comment, London Free Press

January 31, 2012

Immunizations, using disposable unit-dose syringes and /or ampoules with natural rubber seals, leach MBT, a rubber manufacturing catalyst that risks deadly IgE allergic reactions. Health protection agencies have known of the MBT-contamination danger for 30 years (WHO’s Uppsala Reports April 2013) but, because of drug company lobbying, refuse to ban pharmaceutical uses of MBT-rubber (Google “Latex in vaccine packaging, FDA”; MBT is present whenever latex is present). Japan’s syringes and ampoule seals had been free from MBT since 1985 (by using synthetic rubber).  Somehow, in 2011, Sanofi-Pasteur ActHIB vaccine was imported, resulting in 4 baby vaccination deaths (from “a contaminant”); Sinofi-Pasteur ActHIB vaccine was on the FDA  list of vaccines with MBT-rubber (“latex”) packaging. "Letter to the Editor"

March 1, 2013

A new analysis of the 1980-81 epidemic of baby deaths at the Toronto Hospital for Sick Children proved that there was no murder by digoxin poisoning, as was generally believed. “The Nurses are Innocent – The Digoxin Poisoning Fallacy” (Dundurn 2011), revealed that a natural rubber contaminant of injections, MBT, from rubber parts of syringes, drug ampoules and IV administration sets, was allergenic, and a cumulative toxin, to which children were particularly susceptible. MBT compounds reached “potentially toxic” levels in 91 Hammersmith Hospital babies  at the time of the Toronto baby deaths. MBT was being falsely measured as digoxin by the two Toronto Hospital for Sick Children digoxin testing methods – the RIA and the highly-touted HPLC test. Since there was no digoxin poisoning, there were no murders. Rubber’s MBT was the baby killer (McLeans Magazine 2011).

Medical Rubber Anaphylaxis II

January 26, 2016 - Submitted to The Lancet

This article was to inform Lancet readers about the  worldwide continued use of natural rubber seals in syringes and drug ampoules, despite the 1990 Lancet warning that it caused IgE-mediated MBT allergic reactions and deaths; this scenario also involved IgE allergic reactions to local anesthetics, immunization vaccines, insulin and any injection with natural rubber contact. Despite this new information of a continuing worldwide potentially lethal medical hazard, the Lancet failed to publish it, a 30-year problem with articles on MBT contamination of injections (WHO’s Uppsala Reports, April 2013).

bottom of page