What substances are poisonous?
Chances are you’ve heard about a number of poisonous substances. But how do we decide if a substance should be considered a poison? By our definition, it is any chemical that can do harm or cause death – but that would include everything, since every chemical can be a poison if you eat enough of it, even such simple substances as salt or water. On the other hand, you have to eat a LOT of salt before it will kill you, but some chemicals are harmful even in very small amounts, so we can say that some things are more poisonous than others. Some chemicals are good in some amounts and harmful in others. For example, many vitamins and minerals have a range in the amount that is good for you – if you don’t get enough, you will have deficiency symptoms, but if you get too much, you will start to experience toxic effects. So rather than asking whether a substance is poisonous, it makes more sense to ask how poisonous it is. How can we measure how toxic a substance is? How can you determine how
