Lethal dose

From ArticleWorld

The Lethal dose is an indication about the lethality of a substance or type of radiation. It is a measure of how fatal can a substance or a type of radiation be if administered in a certain way.

LD 50

The most common measure of lethal dose is LD50, lethal Dose 50. The Lethal dose depends very much on the subject's resistance, background health, medical history etc. This means that the lethal dose is not the same for all subjects, and this is why it is commonly expressed in quantity of substance/radiation per kilogram of body weight. LD50 is the dose at which 50% of the subjects die.

Until a few years ago, the most common way of testing the lethal dose was using animal subjects to which the substance or radiation was gradually administered. Many researchers are currently shifting away from it and seeking alternative ways.

Most toxic substances

The most toxic substances currently known are the neurotoxins. Neurotoxins are used by some animals as a defense weapon, and the most common example is the batrachotoxin, a poison found on the skins of certain species of frogs in Central and South America. The toxicity of this substance is extremely high, with the LD50 between 0.001 and 0.002 mg/kg of body weight. This means that 0.1 mg of this substance would be enough to paralyse or kill a 70 kg man.