The World’s Deadliest Thing
The Deadly Sausages of Old Stuttgart Town
In late 18th Century Stuttgart, Justinus Kerber, in the spirit of many a great medical pioneer, very nearly killed himself in the name of science. Investigating a series of so called ‘sausage poisonings’, mysterious cases of rapid and often fatal paralysis linked to preserved meats, he dropped the distilled extract of several suspect salamis onto his own tongue.
Given what we now know, Kerber was incredibly fortunate to only suffer from a drying out of the palate, but he did posit that the essence he had isolated might have some medical benefits, an observation that was remarkably prescient. Just over two-hundred years later, that same substance would become the most valuable in the world, spawning a multi-billion-dollar industry. But in the intervening years, it would continue to cause huge suffering, and radically change the food we eat.
Around 1895, whilst investigating the case of a group of musicians who had died after eating cooked ham, a Belgian scientist called Emile van Ermengem identified the bacteria at the heart of Kerber’s sausage poisonings, a disease that had been coined Botulism, after botulus, the Latin for sausage. Later work showed that these bacteria, which Van Ermengem named Clostridium Botulinum, would only grow under certain conditions. The inside of a piece of badly stored, processed meat was ideal, but when conditions changed, the bacteria would shut down, forming highly resistant spores and remaining in that form until conditions were right again for growth.
A few years later, scientists discovered something even more remarkable. The spores that produce these deadly bacteria were almost everywhere. They were found in the soil, on the surface of vegetables, in animal faeces and within riverbeds. They could survive being boiled, being frozen, and cope with highly acidic environments. Thankfully, these spores were also harmless, passing through humans unchanged if ingested. But under the correct conditions, they would turn back into bacteria, producing a deadly neurotoxin. If this toxin was ingested, even in the tiniest quantities imaginable, it would produce a slow paralysis moving down the body, eventually shutting down vital processes like breathing. For anyone unlucky enough to consume it, the survival rate was around 60%.
To grow, Botulinum spores require a low salt, oxygen free environment, with low acidity, enough water, access to protein and a few other nutrients. The inside of a piece of cooked meat is ideal, but so is the inside of many canned foods if they are not processed adequately. As a result, botulism nearly derailed the nascent food canning industry completely, with cases becoming increasingly common as the industry expanded in the early twentieth century. It was not until the 1920s, when Karl Frederick Meyer, a brilliant infectious disease specialist working for the US National Canners Association, formalised sterilisation and temperature control techniques to combat the threat of botulism. Meyer, who also worked on vaccines, disease epidemiology and milk processing, is a largely unheralded hero of global public health. Many consider him the twentieth century’s Pasteur, and his work doubtless saved millions of lives.
To combat botulism in canned foods, it is necessary for all parts of the sealed can to reach an internal temperature of 121C, as this is sufficient to destroy botulinum spores, leaving the contents of the can free from the potential for bacterial growth*. As manufacturers understandably err on the side of caution, this results in a lot of heat energy being put into canned produce, often resulting in a slightly burnt, canned taste, particularly in dairy produce, creamy sauces or other items high in sugars.
An alternative approach is to acidify the contents to a pH below 4.5 (although the effective upper limit is 4.2-4.3 in most production, just to be sure), and then apply heat up to about 91C to kill any bacteria, in a processed known as Pasteurisation. Although the spores remain intact at this temperature, the low acidity means that they will not grow into bacteria or produce their deadly toxin. It is this process that means we can make high quality jars of pasta and curry sauce, processed at lower temperatures, similar to standard cooking. Most tomato-based sauces have a naturally low pH, and many sweet and sour tasting products are also well below pH 4.2, from the naturally present vinegar or citrus. Many other foods will require an additional acidulant, usually vinegar or a citrus concentrate, to make them safe, something that significantly alters the taste.
In this way, Clostridium Botulinum shapes our modern food system. It is why canned foods have a burnt, metallic taste and jarred sauces can sometimes have a harsh acidic note, particularly creamy sauces that are not naturally acidic. It is why you will rarely buy a good quality ambient cheese or bechamel sauce and why delicate aromatic notes are often lost in canned foods. The same bacteria are also responsible for the addition of nitrites to processed meats, as a combination of nitrites and salt inhibit growth, also giving bacon and ham their distinctive metallic tang and pink colour.
It is because of these precautions, and the tireless work of hundreds of food safety experts, that cases of botulism poisoning are extraordinarily rare within our modern food system. In the UK, between 1990 and 2005, there were 5 reported cases affecting 6 people and causing 2 deaths, meaning that you were 15 times more likely to be hit by lightning. The only case linked to a commercially produced food product in that time was non-fatal, involving a man who ate some hummus that had been left out of the fridge for several weeks and smelt so bad that other members of his family refused to go near it. **
It is perhaps strange that such a rare poisoning event shapes our modern food system so profoundly, but this is perhaps because the toxin produced is one of, if not the, deadliest on earth. It has been estimated that in its pure crystalline form, six grams of botulism toxin, about one teaspoon full, would be enough to kill 200 million people. The lethal dose when consumed orally is around 30 billionths of a gram, which if you want a relatable comparison, is about the same as if you cut a single poppy seed into ten thousand equal pieces and ate one of them. It is an amount so tiny, it really doesn’t make sense.
This potency has long attracted the worst sort of attention. As early as 1940, both US and German forces were attempting to develop weapons from botulinum toxin, and it was a threat taken so seriously that Allied forces stockpiled a million doses of antitoxin in advance of the D-Day landings. There have been rumours that various rogue states and terrorist organisations have been refining the poison ever since, but thankfully it has always proved difficult to weaponize, and there has never been a confirmed fatality. Doomsday cult Aum Shinrikyo made a few attempts to deploy it at US military bases in the 1980s, but were so shambolically unsuccessful that their attacks went unnoticed by authorities. In 1991, the Iraqi regime admitted producing large amounts for deployment on warheads, and it was thought that they had at one stage stockpiled enough to kill everyone on earth, although it is unclear how they would have persuaded us all to consume it.
It is certainly not impossible to produce botulinum toxin on an industrial scale, but it was not until the late 1960s that Ed Schantz, a chemist who had worked on purifying the toxin at a US military research institute, was asked by an ophthalmologist Alan Scott if he could supply a sample. Scott wanted to see if the unusual flaccid paralysis effects could be harnessed medically, just as Kerner had suggested years before. He used tiny, injected doses to help alleviate the symptoms of patients with crossed eyes or twitching eyelids and found it to be incredibly effective. In 1989, purified botulinum toxin was approved as a drug under the brand name Oculinum. Scott’s company was purchased by pharmaceutical manufacturer Allergan in 1991, who renamed the drug Botox.
Throughout the 1990s, several potential uses emerged, and Botox is currently licenced as a treatment for muscle spasms, overactive bladders, cerebral palsy and migraines. But it was a chance discovery by a couple of Canadian doctors that was to turn it from a useful muscle relaxant into a blockbuster drug. Jean Carruthers, a Vancouver based ophthalmologist, was using Botox to treat eye spasms, and was surprised when her patient complained about the injection not being administered into her forehead as usual, saying that she enjoyed the smooth skin and young expression it gave her. At the time, Jean’s dermatologist husband Alastair was looking for ways to help patients with frown lines, and the couple teamed up to offer Botox as a cosmetic treatment for the first time.
The rapid, long-lasting and highly noticeable cosmetic effects made Botox a near instant success. In small doses, the same nerve damage that causes fatal paralysis in poisoning cases, helps to remove forehead creases and crow’s feet, with the only side effects being an inability to express emotion using your face, and an occasional case of drooping eyelids. A distinctive wrinkle-free and slightly startled look became fashionable among the Hollywood A-List, and eventually across the world. It is of course deeply ironic that many celebrities who publicly advocated a clean living, chemical-free lifestyle, were also early adopters of a treatment that involves injecting the deadliest substance on earth into your face (looking at you, Paltrow). If any of them were surprised at this seeming paradox, they certainly didn’t show it.
Jean and Alastair Carruthers’s serendipitous conversation would create a multi-billion-dollar business for Allergan. As Botox grew more accessible, it rapidly became the most common cosmetic medical procedure in the world. In 2017, over seven million faces were injected with it, an increase of 800% from the turn of the millennium, generating $2.3 billion in annual sales. Not content with being the deadliest substance on earth, it is likely that the pure crystalline form of Botulinum toxin is now also the most valuable, with an estimated street value of $100 trillion per kilogram. The entire global face paralysing industry is supported by an annual production of just a few milligrams.
On the list of microbes that have shaped humanity, Clostridium Botulinum would have to sit fairly high, hugely impacting our modern food system, tantalising bioterrorists, and creating a multi-billion-dollar industry. Botulism toxin affects us all, shaping the flavour, distribution, storage and packaging of the food we eat. The fact that we rarely have to think about it, is testament to the extraordinary, dedicated work of thousands of food industry professionals around the world, who help create the safe, effective food system we enjoy today.
*This might not be strictly true. There are a few thermophilic (heat loving) microorganisms with spores that can survive these temperatures, but none that cause food borne illness. Being heat loving, most of these microorganisms will usually stay inactive inside cans stored at room temperature, although they can sometimes cause spoilage in warmer climates.
**There was a high-profile UK case affecting 3 children in 2011, that thankfully was non-fatal. This was linked to products produced by the company I worked for at the time, although subsequent investigations found that no one there was at fault. I will write about this sometime, perhaps in a later post, as it is a significant and interesting story.
