8 Things Everyone Gets Wrong About 'Scary' Chemicals
6. Some Chemicals Are Toxic, And Others Are Harmless
Even chemists and other scientists are guilty of this one. Who hasn’t uttered a sentence like “arsenic is poisonous” or “water is non-toxic”?
Ok, maybe they’re not in everyone’s daily lexicon, but you know what I mean.
The truth is that these statements are a bit lazy. What we really mean is that a small amount of arsenic is poisonous, while even quite a large amount of water is relatively harmless (unless, of course, you’re breathing it).
An important concept in chemistry and pharmacology is “the dose makes the poison”. It’s credited to the Swiss German philosopher Paracelsus who said, back in the 16th century: “All things are poison and nothing is without poison, only the dosage makes a thing not poison.” Although he said it German, so there were a lot of ‘Gift’s in there (does it bother anyone else that the German word for poison is gift? Surely that’s got to have caused translational catastrophe at some point? Just my twisted mind? Ok then).
It’s all about quantity. Less than a tenth of a gram of arsenic can be lethal. On the other hand, it’s a substance that occurs naturally in the environment and so it does turn up in our food. Traces of arsenic are common in rice, for example, but so long as you don’t eat rice for every meal, every day, you won’t reach dangerous levels. Likewise everyone can drink a couple of litres of plain old water a day with no problem whatsoever, but six litres in a short space of time might just turn out to be deadly.