Parts per million (ppm): PPM is another unit used to express concentrations, where one part per million represents one part out of one million parts.
Toxicity threshold: The toxicity threshold refers to the level at which exposure to a substance starts causing adverse effects on an organism.
LD50 (Lethal Dose 50): LD50 is a measure of the toxicity of a substance, representing the dose required to cause death in 50% of the test population.