Toxin

"Toxin" is classic pseudoscience terminology.

"Toxin" is a term commonly thrown around by quacks, even though they can't tell you what the exact toxin in question is, how it is absorbed or builds up in the body, why no organisms have evolved methods of disposing of these toxins, or why things like dose, epidemiology, or basic chemistry don't make any difference to the said toxin's effects.

"Toxin" in the scientific and medical sense refers specifically to a metabolic product of a living organism that has deleterious effects either in itself or in another organism at a sufficient dosage. In alternative medicine and food woo, "toxin" is not restricted to metabolic products; woo-meisters often use the word to refer to or to synthetic chemicals (which, if showing any actual toxicity, should correctly be termed "toxicants"). Alternative medicine is often not concerned with whether the dosage is sufficient to cause an actual measurable harmful effect.

Detoxification, more popularly known as cleanses, is big business in the alternative medicine world. Chelation therapy is a more formal — if less popular — quack attempt to remove "toxins", most commonly lead or mercury.

If you are unsure if you're dealing with genuine detoxification woo, simply ask the basic kindergarten question: "Can you please name the compound in question and explain its mechanism of action?". If this question stumps the person in question, snap a Polaroid for remembrance's sake. It's not every day one brushes up this close to textbook woo.

General ignorance
It's an irrational concept, yet an intriguing idea, that modern life so fills us with poisons from polluted air and food additives that we need to be periodically "cleaned out" ("detoxified"). Never mind that natural chemicals in our foods are thousands of times more potent than additives, or that most Americans are healthier, live longer, and can choose from the most healthful food supply ever available. According to a woo-meister, a toxin is any chemical that doesn't belong in a (usually human) body, for whatever reason they think it shouldn't be there. However, alties usually ignore the following:


 * Appealing to nature is not a component of any system of thought that makes even basic sense.
 * Bodies of organisms may have ways of either processing or ejecting those chemicals through digestion, basic liver functions, sweating, vomiting, conjugation, Glucuronidation, and a hundred other things (which explains why studying to be a biologist or chemist can't be done over a weekend, e.g. at a firewalk convention in Tampa, Florida).
 * Some chemicals, such as formaldehyde (a boogeyman amongst the anti-vaccine movement), are found in many natural foods, but are also produced by the bodies of organisms.
 * The dose makes the poison.
 * Many "unnatural" (in the sense of not being part of a normal diet) products have no chemical or biological effect from exposure or ingestion. For example, other than displacing oxygen, breathing helium is harmless, as it does not react with any part of the body and is exhaled with the next breath.
 * The chemistry of living organisms is kind of an actual branch of science and not something you master simply from years of wearing sandals and eating chlorella. Even is vital to your very own, individual health (the lack of it being kind of deadly).