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CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Dose

The amount of a substance taken in, usually expressed per kilogram of body mass (mg/kg) so that different body sizes can be compared. "The dose makes the poison": whether a substance harms you depends on how much, how often and by what route.

Dose–response curvePercentage of a test population killed against dose on a logarithmic scale. The curve is S-shaped; the LD₅₀ is the dose that kills 50 %, here 10 mg per kg of body mass. A lower LD₅₀ means a more toxic substance.0.11101001000050100dose (mg per kg body mass, log scale)% of population killedLD₅₀50 %

The fraction of a population affected rises with dose.

Example

A 60 kg person drinking one cup of coffee (about 95 mg caffeine) takes in 95/60≈1.695 / 60 \approx 1.6 mg/kg, about 120 times less than the rat LD₅₀ of 192 mg/kg.

See alsoLD₅₀Toxicity