The Dose Makes the Poison

Most of you reading this blog are probably against anti-science, anti-intellectual bullshit from the right wing/Republicans; they don’t) (generally) believe in evolution, or the big bang, or stem cell research. There is, however, a complementary strain of bullshit-enthusiasm coming from the left, and we need to be just as skeptical. From vaccine conspiracies to throat chakras causing thyroid problems, it’s clear one’s political leanings are never a guarantee of skepticism. Skepticism is a method that must be consciously applied.

This showed up in my news feed:

Along with the picture was posted an article, which I will quote from to explain why we should be skeptical of claims like this:

The third largest ingredient in Dasani is potassium chloride. If you are to be put death, first you get a barbiturate, then a paralytic agent, and then the chemical to stop your heart (what a coincidence!) you guessed it: potassium chloride! […] But I remember from Chemistry and other sources of information KCl is used for lethal injections and is often times hazardous… so why would it be in bottled water?

Paracelsus, sometimes called the father of toxicology, is credited with the following insight: “All things are poison, and nothing is without poison; only the dose permits something not to be poisonous.”

Everything and anything, including water, can be poisonous at certain doses. Your body is a complex chemical soup that has many different homeostatic equilibria it can be at. Taking a particular medication will shift one aspect of your biochemistry, and other aspects will also change to compensate. Your new equilibrium will be different in more ways that just “old equilibrium + medication.”

One example of this is alcohol. If you drink regularly, your body will get used to always having a depressed central nervous system, and will attempt to compensate for this. If you then suddenly stop drinking, your body’s compensatory ramping up of your CNS can result in a seizure, delirium tremens, or death. If you drink coffee every day, your body will also get used to having dopamine reuptake mildly inhibited (it’s a side effect of blocking adenosine receptors, and also a reason caffeine can be used as a shitty alternative to ADHD medications) and your arteries constricted. Quit caffeine, and suddenly you have a raging headache and hate the world. Take too much of either in one sitting, and you could die from acute toxicity.

The mechanism of delivery is also very important to determining toxicity. If you eat something, it will be absorbed in your digestive tract, immediately processed by the liver, and then sent out into the rest of the blood stream (usually – alcohol is an exception, as it can cross membranes and enter the blood stream directly from the stomach). If you smoke or snort a drug, it will bypass the liver and likely reach a higher concentration in your blood from the same initial dose. Injecting a drug, for obvious reasons, will also give you a much higher concentration of it in your bloodstream than if you had drank it in water.

And that’s why this is so misleading:

“Side effects can include gastrointestinal discomfort including nausea and vomiting, diarrhea and bleeding of the gut. Overdoses cause hyperkalemia which can lead to paresthesia, cardiac conduction blocks, fibrillation and arrhythmias.”

Yes. Those can certainly all be consequences of overdosing on potassium chloride, and yes, potassium chloride is used in lethal injections. There is a reason we don’t execute inmates by having them drink a shit-ton of Dasani. They would not be able to drink the water fast enough to reach a lethal blood concentration. They’d probably die of hyponatremia – the aforementioned condition also known as water poisoning – long before they induced a fatal arrhythmia.

“FDA pregnancy category C.” This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether potassium chloride passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.” Yet there are no warnings of any kind on a bottle of Dasani….”

ERMERHGHERD,what are they putting in our water supply?!

There aren’t any warnings because the dose makes the poison, and the dose of potassium chloride you’d get from drinking Dasani does not rise to the level of a therapeutic dose that could be harmful to a fetus or infant. According to wikipedia, the LD50 – or the dose at which 50% of a population will die – for potassium chloride consumed orally is 2.6g/kg. Intravenous administration drops the LD50 down to 147 milligrams/kg!

I weigh about 65 kilograms. I would need to consume about 169 grams of potassium chloride to have a 50% chance of dying. The article quotes Dasani that, “there is less than 5 mg of KCl in each bottle of water.” In other words, I would need to drink over 33,000 bottles of Dasani in order to – maybe – kill myself. I’d die of water poisoning long before I died of potassium chloride.

That’s why there’s no warning label on the bottle.

Bonus:

One final question for soft drink consumers: the primary ingredient after water and sugar in all of them is always phosphoric acid, which gives the drink its “zing.” Yet phosphoric acid is primarily used outside of the soft drink industry as an industrial solvent, to clean toilet bowls, and to oxidize raw steel, so that it can be painted. Is this something you really want to drink or that your children should be drinking?

The idea that anything used as a solvent or to clean toilet bowls or to oxydize steel makes me think of the dihydrogen monoxide research division.