An exploration of LD50

To understand poisons we must first understand what LD50 is a measure of. LD50 is a value measured in (mass unit for instance mg)/kg. The LD50 tells us the value we'd have to consume per kg of body mass to kill 50% of people, for instance if a person weighed 70kg we would times the LD50 by 70 to find the mass required to kill that person. A real world example of this would be Arsenic which has an LD50 of 13mg/kg, so if we wanted to find the amount required to have a 50% chance of killing a 100kg person we would do 13mgx100 which is 1300mg.

LD50 is a property held by all molecules in our world, the most important distinction however is the size of that LD50. Safe foods we eat everyday have such a large LD50 that it is essentially impossible to ever reach the level of consumption to endanger us, however poisons and toxins have low LD50s with many in the range where even small doses can cause extreme harm.

Some LD50's of famous poisons are listed below:

Poison	Oral LD50
Sodium Cyanide	15 mg/kg
Ricin	1 mg/kg
Arsenic1	13 mg/kg

¹ Arsenic is a sequential poison, sequential poisons build up in your system and can cause long term poisonings

LD50 is listed as the oral dose as many poisons will have different effects and thus different LD50s depending on if it was injected, inhaled or consumed.

Whilst LD50 can be a good judge of a safe dose of a substance, it can concern people that many foods and drinks will have LD50s, this concern can resolved by the knowledge that all foods, regardless of how safe they may be, have an LD50 and only extremely low LD50s are concerning.