What is the famous statement about substances of Paracelsus, the Swiss physician?
The Swiss physician, alchemist and “Farther of toxicology” Paracelsus, initially called Theophrastus Aureolus Bombastus von Hohenheim, once stated “All substances are poisonous; there is none which is not a poison. The right dose differentiates a poison and a remedy”. This quote emphasises how crucial the dosage of the substance in determining whether it is poisonous and how toxic the substance is to the organism. As explained above the LD50 is a measure of the dosage at which 50% of the population dies as a consequence of the xenobiotic however the NOEL is the highest dose or exposure level of a poison where there no noticeable toxic effects on an organism. Therefore poisons with a low NOEL and a Low LD50 will be the most poisonous molecules, meaning that they shall also have the highest toxicity. Notable examples of this include Tetrodotoxin (TTX), a poison starting to appear in molluscs in European waters. TTX blocks sodium channel in the nervous system resulting in neuromuscular paralysis, in particular, the diaphragm and potential death. A recent study showed that using mice, the LD50 of TTX to be 232µg/kg while the NOEL was recorded as 75µg/kg. The two dosages show that the poison has high toxicity and is therefore very poisonous. The dosage is the concentration of the substance in the blood meaning that a very low concentration is required for this molecule to cause illness and death to the organism, in particular organisms with a nervous system.