Toxicity is a Most Misunderstood Term

I don’t believe the average consumer understands the basics, much less any subtleties, of toxicity.  Sadly, the word “chemical,” or something that sounds chemically suspicious, is synonymous with “toxic” among many in America.  Here is a very good example:

Penn and Teller do a darn good job at exposing this nonsense.  But how did we get to this state of anxiety and ignorance?  I don’t know, but I will try my best to help.  I feel like Sisyphus. The concept of toxicity is common sense.  A fundamental rule of toxicology, the study of toxicity, is that toxicity depends on dose.  That is not hard to understand.  Many people take aspirin (an acetylsalicylic acid), for example, to ease headaches, to prevent heart attacks, etc.  There are many medical uses for aspirin, e.g., two 325 milligram tablets every 4 hours to relieve pain.  Most people can tolerate this therapeutic dose.  Any less, and the therapeutic effect might not take place, or a different effect might be manifested.  However, if the dose is exceeded, for example, six 325 milligram tablets every 4 hours, the body may start reacting differently.  Aspirin at this dose might have a greater chance of causing stomach upset, emesis (vomiting) and/or an ulcer, all toxic effects.

The reaction of a human body to a chemical or composition is best expressed on a continuum from “no effect” to “lethal.”  Every chemical I know of can be classified this way. So it is imprecise to say that a chemical or a composition is inherently toxic. Fundamentally, the precise question is “what’s the dose that manifests a toxic effect?”

Oversimplified, there are two ways to measure toxicity, acute toxicity (single dose), and chronic toxicity (repeated exposure over time).  For the purpose of vaccines, I am limiting this blog post to acute toxicity.  There’s a good reason: Most vaccines are given in discrete single doses separated by at least a month, sometimes years.  So the toxicity of a single vaccine is likely best measured this way.

The most common measurement is probably “LD50.”  An LD50 is the dose in grams of ingredient per kilogram of body weight (g/kg) that kills (Lethal Dose) 50% of a population of test animals.  Sounds horrible, right?  Yes, mice, rats, pigs, or whatever test animals chosen, are dosed until they die.  That is the way we humans are protected from our own stupidity (“More is better,” for example) under federal law.  Be thankful for the creation of the FDA and EPA, who are our first lines of defense. The lower the LD50, the more acutely toxic the substance.  Many substances we ingest or use have some low LD50’s.  Here are some examples I pulled from the medical literature freely available on the internet.*  I weigh 141 kg, so I’ll calculate how much it might take to kill me.

  1. Caffeine: 0.2 g/kg, thus, 28 grams might be lethal for me.
  2. Table Salt: 3 g/kg, thus 420 grams might be lethal for me.
  3. Water: 90 g/kg, thus about 13 kilograms might be lethal for me.
  4. Thimerosal (preservative in some vaccines): 0.08 g/kg, thus 11.3 grams might be lethal for me.  A typical vaccine has about 1 microgram (0.000001 g)
  5. Botulism toxin – precisely, onabotulinumtoxin A (This is used in BOTOX treatments): 0.00000001 g/kg, thus about 1.4 micrograms would kill me.  One dosage unit contains the LD50 dose for intraperitoneal injection in mice (I estimate about 2.5 nanograms)  That my friends, is about as toxic a natural substance I know.

So let’s turn our attention to caffeine:  A good espresso will have 100 milligrams (0.1 g) caffeine per espresso cup.  I’d have to have 280 espresso cups in a single sitting to kill me.  Really.  On the other hand, powdered pure caffeine has now found its way on the market (see this advertisement).  For a person 1/3 my weight (47 kg = 103 pounds), it would not take much to kill him, about 9 grams – so little a measuring error can be lethal, or at least put some ripped dude in the hospital with acute caffeine poisoning.

Are you getting my point?  Thanks to all those mice, rats, pigs, and dogs that help us humans be safe by determining what doses of medicines, cosmetics, and other common substances we can tolerate.  You may not like it, but you’re alive because of their deaths. These were honorable sacrifices.**


*Here’s a very good primer in toxicology: Chapter 1 is referenced here.
**Some companies may claim they do not test their products on animals.  I have no doubt that’s true, but it is an empty claim and frankly meaningless.   It turns out that most drugs, pesticides, soaps, cosmetics, and the like are EPA or FDA registered ingredients.  That is, many ingredients in such “non-animal-tested” products were tested on animals, to determine their toxicities, prior to producing and marketing the “non-tested” products.  For example, The Body Shop sells a product with the following ingredient list (This is copied literally word for word from their website):
Aqua/Water/Eau (Solvent), Sodium Laureth Sulfate (Surfactant), Cocamidopropyl Betaine (Surfactant), Glycerin (Humectant), PEG-40 Hydrogenated Castor Oil (Surfactant), Parfum/Fragrance (Fragrance), Sodium Chloride (Viscosity Modifier), PEG-120 Methyl Glucose Dioleate (Viscosity Modifier), Polyglyceryl-2 Caprate (Skin-Conditioning Agent), Sodium Benzoate (Preservative), Mel/Honey/Miel (Humectant), Citric Acid (pH Adjuster), Benzyl Salicylate (Fragrance Ingredient), Ethylhexyl Salicylate (Ultraviolet Light Absorber), Limonene (Fragrance Ingredient), Butyl Methoxydibenzoylmethane (Ultraviolet Light Absorber), Disodium EDTA (Chelating Agent), Linalool (Fragrance Ingredient), Propylene Glycol (Humectant), Eugenol (Fragrance Ingredient), Coumarin (Fragrance Ingredient), Papaver rhoeas flower extract (Skin Conditioning Agent), Geraniol (Fragrance Ingredient), Citronellol (Fragrance Ingredient), Polysorbate 20 (Surfactant), Sodium Hydroxide (pH Adjuster), Denatonium Benzoate (Denaturant), Sorbic Acid (Preservative), CI 19140/Yellow 5 (Colorant), CI 17200/Red 33 (Colorant), CI 42090/Blue 1 (Colorant).
Let’s take coumarin (highlighted in red).  Coumarin has an LD50 of 293 mg/kg (rats).  In other words, somebody had to feed this compound to rats to determine the number.  Thus, while the “product” that contains coumarin may not have been tested on animals, coumarin was.   For whoever has bought into this “non-animal-tested” malarkey, I’m sorry to burst your bubble.  Maybe a nice hot bath with some Body Shop soap will help.
Just to be clear:  I am not saying that The Body Shop performed the rat test on coumarin, far from it.  I am stating that The Body Shop necessarily must rely on toxicity data that somebody generated before including coumarin in a product for humans.  Think about it: otherwise, the product liability could be extraordinary if someone is poisoned.

About patlowder

I'm a chemist, patent attorney, husband of one wife, dad of two sons, and I am (a progressive, whatever that label implies) Christian. I have had a rich, varied life and I give thanks for it. Just to be clear, this blog reflects personal views and is not intended as an advertisement for legal services, or should be considered a "law blog." You should not take anything I say to be a legal opinion on any topic and you don't create an attorney-client relationship by reading it. That requires an executed written contract.
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2 Responses to Toxicity is a Most Misunderstood Term

  1. Pingback: The Royal Quacktitioner | Vaccines – Simplified

  2. gennaro says:

    And you will never know when botulism is around the corner:

    Some roots and tubers also contain cyanide, which may surprise those aiming to live a more organic life.

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