Toxic Carnival: The Dose Makes the Beauty Treatment

As part of the Toxic Carnival started by ScienceGeist, I present my own contribution, as suggested by the Curious Wavefunction. I’m going to talk about Botox.

Botox is an abbreviation of Botulinum toxin, which is a protein produced by the bacteria Clostridium botulinum. That right there tells you is not exactly good for you and in fact it is the most acutely toxin known, with a lethal dose of 1 ng/kg (intravenously) or 3 ng/kg when inhaled. Rather than the small molecule, it is a protein (or really a family of proteins) and causes botulism, a life-threatening paralyzing illness. This can lead to respiratory failure as even the muscles of the lungs are paralyzed.

Despite this extreme toxicity, the toxin has a number of medical uses. Most famously for removing wrinkles, an effect which is not permanent of course but typically lasts for around 8 months, it also has genuine medical uses. It was first used by ophthalmologists to treat a form of crossed eyes (strabismus) and uncontrollable blinking (blepharospasm). Though effective, the treatment also only last a period of months, requiring reinjection 2 or 3 times a year. It might be imagined as a controlled muscle paralysis, so no surprise that it is also useful in treating muscle spasms, though more surprising is that it is used to treat excessive sweating (the first non-muscular application).

The toxin is in fact a series of related proteins, broadly divided in 7 types (A-G) and further divided into subtypes. The structure of two of those are shown here:

Though it is routinely used in medical and cosmetic procedures, it is acutely toxic. The treatment is an antitoxin, as well as ventilation if needed. A tribute to how well the doctors handle it, almost all cases of botulism result from the bacteria in the food supply rather than medical treatments, though there are some side effects, they are mostly minor and treatable. Improperly preserved food and infant botulism are the most common – sadly almost all the deaths from botulism in the US are infants. Infant botulism occurs when the bacteria colonize the intestine of the infant via ingestion of spores, leading to the release of toxin into the bloodstream. Honey has been identified as a major vector for the spores getting into the gut, thus it is strongly advised that no honey is given to any child under 1 year old, as even a taste can introduce the bacteria. Other than that, avoiding the bacteria is by thorough cooking, as the protein is denatured at elevated temperatures, though the spores are not always killed by boiling, meaning it can begin to grow again once conditions are right.

The toxin has also been examined by various groups as a potential bio-weapon. It has been difficult to weaponize, which is perhaps only partly reassuring, especially when you consider that 4 kg of botulinum toxin could, if properly dispersed, kill the entire human population of the planet. Less than a gram is needed to satisfy the annual needs for medical uses. Oh so useful but oh so deadly.