Poisons are substances that cause harm to organisms when sufficient amounts are absorbed, inhaled, or ingested. A toxin is a poisonous substance produced within living cells or organisms.
Although we often associate the word “chemical” with synthetically manufactured poisons, a chemical is not harmful just because it is manufactured, nor is it harmless just because it is natural. Potentially poisonous chemicals can be synthetic (manufactured) or natural. For example, dioxins, some pesticides, and nerve gases are poisonous manufactured chemicals, while belladonna, botulinum, and tetrodotoxin are naturally produced poisonous chemicals. There are also poisonous substances that occur naturally in the soil, such as asbestos and lead.
The seven deadliest chemicals (to humans) are:
- botulinum toxin A (from Clostridium botulinum bacteria)
- tetanus toxin A (from bacteria – Clostridium tetani )
- diphtheria toxin (from bacteria – Corynebacterium diphtheriae )
dioxin (manufactured) - muscarina (from mushrooms – Amanita muscaria )
- bufotoxin (from the common toad – genus Bufo)
- sarin (manufactured)
In science, a toxin is often considered a specific type of poison, a poisonous substance produced within living cells or organisms.
Did you know that five of the seven deadliest known compounds originate from nature? Toxins can be classified as exotoxins (those excreted by an organism, eg, bufotoxin) or endotoxins (toxins that are structurally part of bacteria, eg, botulinum).
Toxins cause damage to organisms when the toxic compound comes into contact with or is absorbed by body tissues. In nature they have two main functions:
- Predation : killing a potential food (eg, spiders, wasps, jellyfish, and sea anemones).
- Defense: discouraging the predator (for example, honey bees, ants, and monarch butterflies, and plants like broccoli produce a toxin to deter insects from eating them).
But today we are not here to talk about dangerous chemicals, just the opposite. Of all the toxic substances manufactured by animals, human beings deal with, through biomedicine, using them, with minimal doses, for a myriad of beneficial objectives for the organism. We review some of them.
