Toxicity

The capacity of a substance to harm a living organism. It always depends on the dose: every substance is toxic at a high enough dose and harmless at a low enough one, and acute toxicity is compared using LD₅₀ values.

Example

Table salt (rat oral LD₅₀ about 3000 mg/kg) and botulinum toxin (about 0.000001 mg/kg) differ in toxicity by a factor of billions, yet both are natural.